85 results on '"Ruben J. Cauchi"'
Search Results
2. Reduced levels of ALS gene DCTN1 induce motor defects in Drosophila
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Rebecca Borg, Paul Herrera, Angie Purkiss, Rebecca Cacciottolo, and Ruben J. Cauchi
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Drosophila ,amyotrophic lateral sclerosis ,DCTN1 ,DCTN1-p150 ,DRED ,CG9026 ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Abstract
Amyotrophic lateral sclerosis (ALS) is a rapidly progressive neuromuscular disease that has a strong genetic component. Deleterious variants in the DCTN1 gene are known to be a cause of ALS in diverse populations. DCTN1 encodes the p150 subunit of the molecular motor dynactin which is a key player in the bidirectional transport of cargos within cells. Whether DCTN1 mutations lead to the disease through either a gain or loss of function mechanism remains unresolved. Moreover, the contribution of non-neuronal cell types, especially muscle tissue, to ALS phenotypes in DCTN1 carriers is unknown. Here we show that gene silencing of Dctn1, the Drosophila main orthologue of DCTN1, either in neurons or muscles is sufficient to cause climbing and flight defects in adult flies. We also identify Dred, a protein with high homology to Drosophila Dctn1 and human DCTN1, that on loss of function also leads to motoric impairments. A global reduction of Dctn1 induced a significant reduction in the mobility of larvae and neuromuscular junction (NMJ) deficits prior to death at the pupal stage. RNA-seq and transcriptome profiling revealed splicing alterations in genes required for synapse organisation and function, which may explain the observed motor dysfunction and synaptic defects downstream of Dctn1 ablation. Our findings support the possibility that loss of DCTN1 function can lead to ALS and underscore an important requirement for DCTN1 in muscle in addition to neurons.
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- 2023
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3. ACE and ACE2: insights from Drosophila and implications for COVID-19
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Paul Herrera and Ruben J. Cauchi
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SARS-CoV-2 ,COVID-19 ,Drosophila ,Ance ,Acer ,ACE ,Science (General) ,Q1-390 ,Social sciences (General) ,H1-99 - Abstract
Angiotensin-converting enzyme (ACE) and its homologue ACE2 are key regulators of the renin-angiotensin system and thereby cardiovascular function through their zinc-metallopeptidase activity on vasoactive peptides. ACE2 also serves as the receptor for the cellular entry of various coronaviruses including the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is responsible for the coronavirus disease 2019 (COVID-19). The unprecedented scale of the COVID-19 pandemic has spurred the use of mammalian models to investigate the SARS-ACE2 relationship and knowledge gained from such research has accelerated development of vaccines and therapeutics. Recent studies have just started to underscore the utility of the fruit fly Drosophila melanogaster as a model system to study virus-host interactions and pathogenicity. Notably, the remarkable existence of catalytically functional ACE and ACE2 orthologues in Drosophila, discovered more than two decades ago, provides a unique opportunity for further developing this model organism to better understand COVID-19 in addition to identifying coronavirus preventative and therapeutic interventions targeting ACE2. Here, we review the studies that revealed crucial insights on the biochemistry and physiology of Ance and Acer, two out of the six Drosophila ACE family members with the greatest homology to human ACE and ACE2. We highlight shared in vivo functions outside of the renin-angiotensin system, which is not conserved in flies. Importantly, we identify knowledge gaps that can be filled by further research and outline ways that can raise Drosophila to a powerful model system to combat SARS-CoV-2 and its threatening vaccine-evading variants.
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- 2021
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4. Loss of amyotrophic lateral sclerosis risk factor SCFD1 causes motor dysfunction in Drosophila
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Rebecca Borg, Angie Purkiss, Rebecca Cacciottolo, Paul Herrera, and Ruben J. Cauchi
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Aging ,General Neuroscience ,Neurology (clinical) ,Geriatrics and Gerontology ,Developmental Biology - Published
- 2023
5. Splicing Defects of the Profilin Gene Alter Actin Dynamics in an S. pombe SMN Mutant
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Marie Antoine, Kristin L. Patrick, Johann Soret, Pauline Duc, Florence Rage, Rebecca Cacciottolo, Kelly E. Nissen, Ruben J. Cauchi, Nevan J. Krogan, Christine Guthrie, Yannick Gachet, and Rémy Bordonné
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Science - Abstract
Summary: Spinal muscular atrophy (SMA) is a devastating motor neuron disorder caused by mutations in the survival motor neuron (SMN) gene. It remains unclear how SMN deficiency leads to the loss of motor neurons. By screening Schizosaccharomyces pombe, we found that the growth defect of an SMN mutant can be alleviated by deletion of the actin-capping protein subunit gene acp1+. We show that SMN mutated cells have splicing defects in the profilin gene, which thus directly hinder actin cytoskeleton homeostasis including endocytosis and cytokinesis. We conclude that deletion of acp1+ in an SMN mutant background compensates for actin cytoskeleton alterations by restoring redistribution of actin monomers between different types of cellular actin networks. Our data reveal a direct correlation between an impaired function of SMN in snRNP assembly and defects in actin dynamics. They also point to important common features in the pathogenic mechanism of SMA and ALS. : Biological Sciences; Molecular Biology; Molecular Genetics; Cell Biology Subject Areas: Biological Sciences, Molecular Biology, Molecular Genetics, Cell Biology
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- 2020
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6. Genetic screen identifies a requirement for SMN in mRNA localisation within the Drosophila oocyte
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Beppe Aquilina and Ruben J. Cauchi
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Survival motor neuron ,SMN ,Genetic screen ,Spinal muscular atrophy ,mRNA localisation ,Gurken ,Medicine ,Biology (General) ,QH301-705.5 ,Science (General) ,Q1-390 - Abstract
Abstract Objective Spinal muscular atrophy (SMA) results from insufficient levels of the survival motor neuron (SMN) protein. Drosophila is conducive to large-scale genetic-modifier screens which can reveal novel pathways underpinning the disease mechanism. We tested the ability of a large collection of genomic deletions to enhance SMN-dependent lethality. To test our design, we asked whether our study can identify loci containing genes identified in previous genetic screens. Our objective was to find a common link between genes flagged in independent screens, which would allow us to expose novel functions for SMN in vivo. Results Out of 128 chromosome deficiency lines, 12 (9.4%) were found to consistently depress adult viability when crossed to SMN loss-of-function heterozygotes. In their majority, the enhancing deletions harboured genes that were previously identified as genetic modifiers, hence, validating the design of the screen. Importantly, gene overlap allowed us to flag genes with a role in post-transcriptional regulation of mRNAs that are crucial for determining the axes of the oocyte and future embryo. We find that SMN is also required for the correct localisation of gurken and oskar mRNAs in oocytes. These findings extend the role of SMN in oogenesis by identifying a key requirement for mRNA trafficking.
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- 2018
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7. Disruption of Survival Motor Neuron in Glia Impacts Survival but has no Effect on Neuromuscular Function in Drosophila
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Marija, Farrugia, Neville, Vassallo, and Ruben J, Cauchi
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DNA-Binding Proteins ,Motor Neurons ,Muscular Atrophy, Spinal ,Aging ,General Neuroscience ,Animals ,Drosophila ,SMN Complex Proteins ,Ribonucleoproteins, Small Nuclear ,Neuroglia ,Survival of Motor Neuron 1 Protein - Abstract
Increasing evidence points to the involvement of cell types other than motor neurons in both amyotrophic lateral sclerosis (ALS) and spinal muscular atrophy (SMA), the predominant motor neuron disease in adults and infants, respectively. The contribution of glia to ALS pathophysiology is well documented. Studies have since focused on evaluating the contribution of glia in SMA. Here, we made use of the Drosophila model to ask whether the survival motor neuron (Smn) protein, the causative factor for SMA, is required selectively in glia. We show that the specific loss of Smn function in glia during development reduced survival to adulthood but did not affect motoric performance or neuromuscular junction (NMJ) morphology in flies. In contrast, gain rather than loss of ALS-linked TDP-43, FUS or C9orf72 function in glia induced significant defects in motor behaviour in addition to reduced survival. Furthermore, glia-specific gain of TDP-43 function caused both NMJ defects and muscle atrophy. Smn together with Gemins 2-8 and Unrip, form the Smn complex which is indispensable for the assembly of spliceosomal small nuclear ribonucleoproteins (snRNPs). We show that glial-selective perturbation of Smn complex components or disruption of key snRNP biogenesis factors pICln and Tgs1, induce deleterious effects on adult fly viability but, similar to Smn reduction, had no negative effect on neuromuscular function. Our findings suggest that the role of Smn in snRNP biogenesis as part of the Smn complex is required in glia for the survival of the organism, underscoring the importance of glial cells in SMA disease formation.
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- 2022
8. Disruption of snRNP biogenesis factors Tgs1 and pICln induces phenotypes that mirror aspects of SMN-Gemins complex perturbation in Drosophila, providing new insights into spinal muscular atrophy
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Rebecca M. Borg, Benji Fenech Salerno, Neville Vassallo, Rémy Bordonne, and Ruben J. Cauchi
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SMN complex ,snRNP assembly ,Unrip ,Strap ,wmd ,pICln ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Abstract
The neuromuscular disorder, spinal muscular atrophy (SMA), results from insufficient levels of the survival motor neuron (SMN) protein. Together with Gemins 2–8 and Unrip, SMN forms the large macromolecular SMN-Gemins complex, which is known to be indispensable for chaperoning the assembly of spliceosomal small nuclear ribonucleoproteins (snRNPs). It remains unclear whether disruption of this function is responsible for the selective neuromuscular degeneration in SMA. In the present study, we first show that loss of wmd, the Drosophila Unrip orthologue, has a negative impact on the motor system. However, due to lack of a functional relationship between wmd/Unrip and Gemin3, it is likely that Unrip joined the SMN-Gemins complex only recently in evolution. Second, we uncover that disruption of either Tgs1 or pICln, two cardinal players in snRNP biogenesis, results in viability and motor phenotypes that closely resemble those previously uncovered on loss of the constituent members of the SMN-Gemins complex. Interestingly, overexpression of both factors leads to motor dysfunction in Drosophila, a situation analogous to that of Gemin2. Toxicity is conserved in the yeast S. pombe where pICln overexpression induces a surplus of Sm proteins in the cytoplasm, indicating that a block in snRNP biogenesis is partly responsible for this phenotype. Importantly, we show a strong functional relationship and a physical interaction between Gemin3 and either Tgs1 or pICln. We propose that snRNP biogenesis is the pathway connecting the SMN-Gemins complex to a functional neuromuscular system, and its disturbance most likely leads to the motor dysfunction that is typical in SMA.
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- 2016
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9. Genetic landscape of ALS in Malta based on a quinquennial analysis
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Maia Farrugia Wismayer, Andrew Farrugia Wismayer, Rebecca Borg, Karl Bonavia, André Abela, Charmaine Chircop, Josanne Aquilina, Doriette Soler, Adrian Pace, Malcolm Vella, Neville Vassallo, and Ruben J. Cauchi
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Aging ,Neuromuscular diseases ,Motor neurons -- Diseases ,General Neuroscience ,Neurology (clinical) ,Geriatrics and Gerontology ,Amyotrophic lateral sclerosis -- Patients -- Malta ,Nervous system -- Degeneration ,Genetics -- Malta ,Developmental Biology - Abstract
Genetic risk for amyotrophic lateral sclerosis (ALS) is highly elevated in genetic isolates, like the island population of Malta in the south of Europe, providing a unique opportunity to investigate the genetics of this disease. Here we characterize the clinical phenotype and genetic profile of the largest series of Maltese ALS patients to date identified throughout a 5-year window. Cases and controls underwent neuromuscular assessment and analysis of rare variants in ALS causative or risk genes following whole genome sequencing. Potentially damaging variants or repeat expansions were identified in more than 45% of all patients. The most commonly affected genes were ALS2, DAO, SETX and SPG11, an infrequent cause of ALS in Europeans. We also confirmed a significant association between ATXN1 intermediate repeats and increased disease risk. Damaging variants in major ALS genes C9orf72, SOD1, TARDBP and FUS were however either absent or rare in Maltese ALS patients. Overall, our study underscores a population that is an outlier within Europe and one that represents a high percentage of genetically explained cases., peer-reviewed
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- 2023
10. Extract from the Marine Seaweed Padina pavonica Protects Mitochondrial Biomembranes from Damage by Amyloidogenic Peptides
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Mario Caruana, Angelique Camilleri, Maria Ylenia Farrugia, Stephanie Ghio, Michaela Jakubíčková, Ruben J. Cauchi, and Neville Vassallo
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Padina pavonica seaweed extract ,Alzheimer’s disease ,Parkinson’s disease ,mitochondria ,amyloidogenic proteins ,membrane permeabilization ,Organic chemistry ,QD241-441 - Abstract
The identification of compounds which protect the double-membrane of mitochondrial organelles from disruption by toxic confomers of amyloid proteins may offer a therapeutic strategy to combat human neurodegenerative diseases. Here, we exploited an extract from the marine brown seaweed Padina pavonica (PPE) as a vital source of natural bioactive compounds to protect mitochondrial membranes against insult by oligomeric aggregates of the amyloidogenic proteins amyloid-β (Aβ), α-synuclein (α-syn) and tau, which are currently considered to be major targets for drug discovery in Alzheimer’s disease (AD) and Parkinson’s disease (PD). We show that PPE manifested a significant inhibitory effect against swelling of isolated mitochondria exposed to the amyloid oligomers, and attenuated the release of cytochrome c from the mitochondria. Using cardiolipin-enriched synthetic lipid membranes, we also show that dye leakage from fluorophore-loaded vesicles and formation of channel-like pores in planar bilayer membranes are largely prevented by incubating the oligomeric aggregates with PPE. Lastly, we demonstrate that PPE curtails the ability of Aβ42 and α-syn monomers to self-assemble into larger β-aggregate structures, as well as potently disrupts their respective amyloid fibrils. In conclusion, the mito-protective and anti-aggregator biological activities of Padina pavonica extract may be of therapeutic value in neurodegenerative proteinopathies, such as AD and PD.
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- 2021
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11. Spinal Muscular Atrophy: From Defective Chaperoning of snRNP Assembly to Neuromuscular Dysfunction
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Maia Lanfranco, Neville Vassallo, and Ruben J. Cauchi
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survival motor neuron ,SMN-Gemins complex ,snRNP assembly ,missplicing ,motor neuron disease (MND) ,amyotrophic lateral sclerosis (ALS) ,Biology (General) ,QH301-705.5 - Abstract
Spinal Muscular Atrophy (SMA) is a neuromuscular disorder that results from decreased levels of the survival motor neuron (SMN) protein. SMN is part of a multiprotein complex that also includes Gemins 2–8 and Unrip. The SMN-Gemins complex cooperates with the protein arginine methyltransferase 5 (PRMT5) complex, whose constituents include WD45, PRMT5 and pICln. Both complexes function as molecular chaperones, interacting with and assisting in the assembly of an Sm protein core onto small nuclear RNAs (snRNAs) to generate small nuclear ribonucleoproteins (snRNPs), which are the operating components of the spliceosome. Molecular and structural studies have refined our knowledge of the key events taking place within the crowded environment of cells and the numerous precautions undertaken to ensure the faithful assembly of snRNPs. Nonetheless, it remains unclear whether a loss of chaperoning in snRNP assembly, considered as a “housekeeping” activity, is responsible for the selective neuromuscular phenotype in SMA. This review thus shines light on in vivo studies that point toward disturbances in snRNP assembly and the consequential transcriptome abnormalities as the primary drivers of the progressive neuromuscular degeneration underpinning the disease. Disruption of U1 snRNP or snRNP assembly factors other than SMN induces phenotypes that mirror aspects of SMN deficiency, and splicing defects, described in numerous SMA models, can lead to a DNA damage and stress response that compromises the survival of the motor system. Restoring the correct chaperoning of snRNP assembly is therefore predicted to enhance the benefit of SMA therapeutic modalities based on augmenting SMN expression.
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- 2017
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12. Putative role of red wine polyphenols against brain pathology in Alzheimer’s and Parkinson’s disease
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Mario Caruana, Ruben J Cauchi, and Neville Vassallo
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Polyphenols ,Alzheimer's disease ,Neuroprotection ,Parkinson's disease ,resveratrol ,bioavailability ,Nutrition. Foods and food supply ,TX341-641 - Abstract
Alzheimer’s disease (AD) and Parkinson’s disease (PD) are the most common age-related neurodegenerative disorders and hence pose remarkable socio-economical burdens to both families and state. Although AD and PD have different clinical and neuropathological features, they share common molecular mechanisms which appear to be triggered by multi-factorial events such as protein aggregation, mitochondrial dysfunction, oxidative stress (OS) and neuroinflammation, ultimately leading to neuronal cell death. Currently, there are no established and validated disease-modifying strategies for either AD or PD. Among the various lifestyle factors that may prevent or slow age-related neurodegenerative diseases, epidemiological studies on moderate consumption of red wine, especially as part of a holistic Mediterranean diet, have attracted increasing interest. Red wine is particularly rich in specific polyphenolic compounds which appear to affect the biological processes of AD and PD, such as quercetin, myricetin, catechins, tannins, anthocyanidins, resveratrol and ferulic acid. Indeed, there is now a consistent body of in vitro and in vivo data on the neuroprotective effects of red wine polyphenols showing that they do not merely possess anti-oxidant properties, but may additionally act upon, in a multi-target manner, the underlying key mechanisms featuring in both AD and PD. Further, it is important that bioavailability issues are addressed in order for neuroprotection to be relevant in a clinical study scenario. This review summarises the current knowledge about the major classes of red wine polyphenols and places into perspective their potential to be considered as nutraceuticals to target neuropathology in AD and PD.
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- 2016
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13. Genetic Interactions between the Members of the SMN-Gemins Complex in Drosophila.
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Rebecca M Borg, Rémy Bordonne, Neville Vassallo, and Ruben J Cauchi
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Medicine ,Science - Abstract
The SMN-Gemins complex is composed of Gemins 2-8, Unrip and the survival motor neuron (SMN) protein. Limiting levels of SMN result in the neuromuscular disorder, spinal muscular atrophy (SMA), which is presently untreatable. The most-documented function of the SMN-Gemins complex concerns the assembly of spliceosomal small nuclear ribonucleoproteins (snRNPs). Despite multiple genetic studies, the Gemin proteins have not been identified as prominent modifiers of SMN-associated mutant phenotypes. In the present report, we make use of the Drosophila model organism to investigate whether viability and motor phenotypes associated with a hypomorphic Gemin3 mutant are enhanced by changes in the levels of SMN, Gemin2 and Gemin5 brought about by various genetic manipulations. We show a modifier effect by all three members of the minimalistic fly SMN-Gemins complex within the muscle compartment of the motor unit. Interestingly, muscle-specific overexpression of Gemin2 was by itself sufficient to depress normal motor function and its enhanced upregulation in all tissues leads to a decline in fly viability. The toxicity associated with increased Gemin2 levels is conserved in the yeast S. pombe in which we find that the cytoplasmic retention of Sm proteins, likely reflecting a block in the snRNP assembly pathway, is a contributing factor. We propose that a disruption in the normal stoichiometry of the SMN-Gemins complex depresses its function with consequences that are detrimental to the motor system.
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- 2015
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14. GEMINs: Potential Therapeutic Targets for Spinal Muscular Atrophy?
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Rebecca eBorg and Ruben J Cauchi
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Motor Neuron Disease ,motor neuron degeneration ,Survival motor neuron ,spinal muscular atrophy ,GEMINs ,small nuclear ribonucleoprotein assembly ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Abstract
The motor neuron degenerative disease spinal muscular atrophy (SMA) remains one of the most frequently inherited causes of infant mortality. Afflicted patients loose the survival motor neuron 1 (SMN1) gene but retain one or more copies of SMN2, a homologue that is incorrectly spliced. Primary treatment strategies for SMA aim at boosting SMN protein levels, which are insufficient in patients. SMN is known to partner with a set of diverse proteins collectively known as GEMINs to form a macromolecular complex. The SMN-GEMINs complex is indispensible for chaperoning the assembly of small nuclear ribonucleoproteins (snRNPs), which are key for pre-mRNA splicing. Pharmaceutics that alleviate the neuromuscular phenotype by restoring the fundamental function of SMN without augmenting its levels are also crucial in the development of an effective treatment. Their use as an adjunct therapy is predicted to enhance benefit to patients. Inspired by the surprising discovery revealing a premier role for GEMINs in snRNP biogenesis together with in vivo studies documenting their requirement for the correct function of the motor system, this review speculates on whether GEMINs constitute valid targets for SMA therapeutic development.
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- 2014
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15. Genome-wide study of DNA methylation in Amyotrophic Lateral Sclerosis identifies differentially methylated loci and implicates metabolic, inflammatory and cholesterol pathways
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Orla Hardiman, Karen E. Morrison, Johnathan Cooper-Knock, Susan Mathers, Matthieu Moisse, Kevin P. Kenna, Michal Zabari, Ruben J. Cauchi, Jonathan Mill, Maurizio Grassano, Paul J. Hop, de Carvalho M, Allan F. McRae, John Landers, Heiko Runz, Basak An, Lerner Y, Mònica Povedano, Drory, Patrick Vourc'h, Philippe Couratier, van Rheenen W, Jan H. Veldink, Denis Baird, Antonia Ratti, Van Damme P, Garth A. Nicholson, Andrea Calvo, van Vugt Jj, Nicola Ticozzi, Eilis Hannon, Antonio Canosa, Silani, Matthew C. Kiernan, Ian P. Blair, Guy A. Rouleau, Mitne Neto M, Kelly L. Williams, Christopher Shaw, Emma Walker, Markus Weber, Frederik J. Steyn, Anjali K. Henders, Peter M. Andersen, Marta F. Nabais, Henk-Jan Westeneng, Dominic B. Rowe, Ramona A. J. Zwamborn, Salas T, Susana Pinto, Shyuan T. Ngo, van den Berg Lh, Sarah Furlong, Adriano Chiò, Mora Pardina Js, Marc Gotkine, Leanne Wallace, Al Khleifat A, Naomi R. Wray, Tian Lin, Roger Pamphlett, Ellen A. Tsai, Alfredo Iacoangeli, Gijs H.P. Tazelaar, Robert D. Henderson, van Es Ma, Pamela J. Shaw, Annelot M. Dekker, Ammar Al-Chalabi, Pamela A. McCombe, Maura Brunetti, Merrilee Needham, Philippe Corcia, Karen A. Mather, Gemma Shireby, Jay P. Ross, Russell L. McLaughlin, Pasterkamp Rj, van Eijk Kr, Patrick A. Dion, Cristina Moglia, Perminder S. Sachdev, and Fleur C. Garton
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Genetics ,Genome-wide association study ,Disease ,Biology ,medicine.disease ,Genome ,Blood cell ,medicine.anatomical_structure ,White blood cell ,DNA methylation ,Brain MEND Consortium ,medicine ,BIOS Consortium ,Amyotrophic lateral sclerosis ,Gene - Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease with an estimated heritability of around 50%. DNA methylation patterns can serve as biomarkers of (past) exposures and disease progression, as well as providing a potential mechanism that mediates genetic or environmental risk. Here, we present a blood-based epigenome-wide association study (EWAS) meta-analysis in 10,462 samples (7,344 ALS patients and 3,118 controls), representing the largest case-control study of DNA methylation for any disease to date. We identified a total of 45 differentially methylated positions (DMPs) annotated to 42 genes, which are enriched for pathways and traits related to metabolism, cholesterol biosynthesis, and immunity. We show that DNA-methylation-based proxies for HDL-cholesterol, BMI, white blood cell (WBC) proportions and alcohol intake were independently associated with ALS. Integration of these results with our latest GWAS showed that cholesterol biosynthesis was causally related to ALS. Finally, we found that DNA methylation levels at several DMPs and blood cell proportion estimates derived from DNA methylation data, are associated with survival rate in patients, and could represent indicators of underlying disease processes.
- Published
- 2021
16. SOD1 D91A variant in the southernmost tip of Europeb: a heterozygous ALS patient resident on the island of Gozo
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Adrian Pace, Ruben J. Cauchi, Maia Farrugia Wismayer, Andrew Farrugia Wismayer, and Neville Vassallo
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Heterozygote ,Pediatrics ,medicine.medical_specialty ,Population ,SOD1 ,Late onset ,Superoxide dismutase ,Biology ,Superoxide Dismutase-1 ,Genetics ,medicine ,Humans ,Amyotrophic lateral sclerosis ,education ,Genetics (clinical) ,Motor neurons ,education.field_of_study ,geography ,geography.geographical_feature_category ,High prevalence ,Amyotrophic Lateral Sclerosis ,medicine.disease ,language.human_language ,Europe ,Maltese ,Respiratory failure ,Mutation ,Archipelago ,language - Abstract
Amyotrophic lateral sclerosis (ALS) is frequently caused by mutations in the SOD1 gene. Here, we report the first SOD1 variant in Malta, an archipelago of three inhabited islands in southern Europe. We describe a patient with a sporadic form of ALS living on the island of Gozo in which the heterozygous SOD1 c.272A>C; p.(Asp91Ala) variant was detected. The patient had a late onset (79 years), sensory impairments and rapid disease progression culminating in respiratory failure. ALS has not yet developed in any of the three additional family members in which the D91A variant was identified. None of the healthy controls from the Maltese population were found to carry this variant. This report underscores the high prevalence of the D91A variant in Europe, despite the presence of a North-South gradient in its frequency, and confirms that this variant can be associated with dominant cases in Mediterranean countries., peer-reviewed
- Published
- 2021
17. The Gemin associates of survival motor neuron are required for motor function in Drosophila.
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Rebecca Borg and Ruben J Cauchi
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Medicine ,Science - Abstract
Membership of the survival motor neuron (SMN) complex extends to nine factors, including the SMN protein, the product of the spinal muscular atrophy (SMA) disease gene, Gemins 2-8 and Unrip. The best-characterised function of this macromolecular machine is the assembly of the Sm-class of uridine-rich small nuclear ribonucleoprotein (snRNP) particles and each SMN complex member has a key role during this process. So far, however, only little is known about the function of the individual Gemin components in vivo. Here, we make use of the Drosophila model organism to uncover loss-of-function phenotypes of Gemin2, Gemin3 and Gemin5, which together with SMN form the minimalistic fly SMN complex. We show that ectopic overexpression of the dead helicase Gem3(ΔN) mutant or knockdown of Gemin3 result in similar motor phenotypes, when restricted to muscle, and in combination cause lethality, hence suggesting that Gem3(ΔN) overexpression mimics a loss-of-function. Based on the localisation pattern of Gem3(ΔN), we predict that the nucleus is the primary site of the antimorphic or dominant-negative mechanism of Gem3(ΔN)-mediated interference. Interestingly, phenotypes induced by human SMN overexpression in Drosophila exhibit similarities to those induced by overexpression of Gem3(ΔN). Through enhanced knockdown we also uncover a requirement of Gemin2, Gemin3 and Gemin5 for viability and motor behaviour, including locomotion as well as flight, in muscle. Notably, in the case of Gemin3 and Gemin5, such function also depends on adequate levels of the respective protein in neurons. Overall, these findings lead us to speculate that absence of any one member is sufficient to arrest the SMN-Gemins complex function in a nucleocentric pathway, which is critical for motor function in vivo.
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- 2013
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18. Genetic analysis of ALS cases in the isolated island population of Malta
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Rebecca M. Borg, Neville Vassallo, Andrew Farrugia Wismayer, Ruben J. Cauchi, Karl Bonavia, Maia Farrugia Wismayer, Malcolm Vella, Joke J.F.A. van Vugt, Brendan J. Kenna, Kevin P. Kenna, and Jan H. Veldink
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0301 basic medicine ,Adult ,Male ,medicine.medical_specialty ,Reproductive Isolation ,Population ,Biology ,TARDBP ,Genetic analysis ,03 medical and health sciences ,0302 clinical medicine ,Sex Factors ,Gene Frequency ,C9orf72 ,Epidemiology ,Genetics ,medicine ,Prevalence ,Humans ,Amyotrophic lateral sclerosis ,education ,Gene ,Genetics (clinical) ,Aged ,Aged, 80 and over ,education.field_of_study ,Malta ,Amyotrophic Lateral Sclerosis ,Age Factors ,Middle Aged ,medicine.disease ,030104 developmental biology ,Genetic Loci ,Mutation ,Female ,Trinucleotide repeat expansion ,030217 neurology & neurosurgery - Abstract
Genetic isolates are compelling tools for mapping genes of inherited disorders. The archipelago of Malta, a sovereign microstate in the south of Europe is home to a geographically and culturally isolated population. Here, we investigate the epidemiology and genetic profile of Maltese patients with amyotrophic lateral sclerosis (ALS), identified throughout a 2-year window. Cases were largely male (66.7%) with a predominant spinal onset of symptoms (70.8%). Disease onset occurred around mid-age (median age: 64 years, men; 59.5 years, female); 12.5% had familial ALS (fALS). Annual incidence rate was 2.48 (95% CI 1.59–3.68) per 100,000 person-years. Male-to-female incidence ratio was 1.93:1. Prevalence was 3.44 (95% CI 2.01–5.52) cases per 100,000 inhabitants on 31st December 2018. Whole-genome sequencing allowed us to determine rare DNA variants that change the protein-coding sequence of ALS-associated genes. Interestingly, the Maltese ALS patient cohort was found to be negative for deleterious variants in C9orf72, SOD1, TARDBP or FUS genes, which are the most commonly mutated ALS genes globally. Nonetheless, ALS-associated repeat expansions were identified in ATXN2 and NIPA1. Variants predicted to be damaging were also detected in ALS2, DAO, DCTN1, ERBB4, SETX, SCFD1 and SPG11. A total of 40% of patients with sporadic ALS had a rare and deleterious variant or repeat expansion in an ALS-associated gene, whilst the genetic cause of two thirds of fALS cases could not be pinpointed to known ALS genes or risk loci. This warrants further studies to elucidate novel genes that cause ALS in this unique population isolate.
- Published
- 2020
19. Toxic oligomers of the amyloidogenic HypF-N protein form pores in mitochondrial membranes
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Stephanie Ghio, Sara Cappelli, Claude Farrugia, Angelique Camilleri, Neville Vassallo, Maria Ylenia Farrugia, Mario Caruana, Fabrizio Chiti, and Ruben J. Cauchi
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0301 basic medicine ,Protein Conformation ,Lipid Bilayers ,Cell ,lcsh:Medicine ,Bilayer lipid membranes ,Mitochondrion ,Oligomer ,chemistry.chemical_compound ,0302 clinical medicine ,Escherichia coli -- Metabolism ,lcsh:Science ,Membrane Potential, Mitochondrial ,Membrane potential ,Liposome ,Multidisciplinary ,biology ,Escherichia coli Proteins ,Cytochrome c ,Neurochemistry ,Neurodegenerative Diseases ,Carboxylic acids -- Analysis ,Amyloid -- Metabolism ,Lipids ,Mitochondria ,medicine.anatomical_structure ,Membrane ,Ion channels ,Mitochondrial Membranes ,alpha-Synuclein ,Hydrophobic and Hydrophilic Interactions ,Amyloid ,Cardiolipins ,Phospholipid ,tau Proteins ,Article ,Alpha-synuclein ,Structure-Activity Relationship ,03 medical and health sciences ,Hydrophobic surfaces ,Escherichia coli ,medicine ,Humans ,Protein folding ,Nervous system -- Diseases ,Proteins -- Conformation ,Hydrophilidae ,Amyloid beta-Peptides ,Mitochondrial membranes ,Structure-activity relationships (Biochemistry) ,lcsh:R ,Amyloid beta-protein precursor -- Metabolism ,030104 developmental biology ,chemistry ,Carboxyl and Carbamoyl Transferases ,biology.protein ,Biophysics ,lcsh:Q ,Protein Multimerization ,030217 neurology & neurosurgery - Abstract
Studies on the amyloidogenic N-terminal domain of the E. coli HypF protein (HypF-N) have contributed significantly to a detailed understanding of the pathogenic mechanisms in neurodegenerative diseases characterised by the formation of misfolded oligomers, by proteins such as amyloid-β, α-synuclein and tau. Given that both cell membranes and mitochondria are increasingly recognised as key targets of oligomer toxicity, we investigated the damaging effects of aggregates of HypF-N on mitochondrial membranes. Essentially, we found that HypF-N oligomers characterised by high surface hydrophobicity (type A) were able to trigger a robust permeabilisation of mito-mimetic liposomes possessing cardiolipin-rich membranes and dysfunction of isolated mitochondria, as demonstrated by a combination of mitochondrial shrinking, lowering of mitochondrial membrane potential and cytochrome c release. Furthermore, using single-channel electrophysiology recordings we obtained evidence that the type A aggregates induced currents reflecting formation of ion-conducting pores in mito-mimetic planar phospholipid bilayers, with multi-level conductances ranging in the hundreds of pS at negative membrane voltages. Conversely, HypF-N oligomers with low surface hydrophobicity (type B) could not permeabilise or porate mitochondrial membranes. These results suggest an inherent toxicity of membrane-active aggregates of amyloid-forming proteins to mitochondria, and that targeting of oligomer-mitochondrial membrane interactions might therefore afford protection against such damage., peer-reviewed
- Published
- 2020
20. Splicing Defects of the Profilin Gene Alter Actin Dynamics in an S. pombe SMN Mutant
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Kelly E. Nissen, Johann Soret, Nevan J. Krogan, Rémy Bordonné, Kristin L. Patrick, Marie Antoine, Yannick Gachet, Pauline Duc, Florence Rage, Ruben J. Cauchi, Rebecca Cacciottolo, Christine Guthrie, Institut de Génétique Moléculaire de Montpellier (IGMM), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM), Laboratoire de Biologie Cellulaire et Moléculaire du Contrôle de la Prolifération (LBCMCP), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Centre de Biologie Intégrative (CBI), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre de Biologie Intégrative (CBI), and Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)
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0301 basic medicine ,Molecular biology ,animal diseases ,[SDV]Life Sciences [q-bio] ,Mutant ,02 engineering and technology ,[SDV.BC]Life Sciences [q-bio]/Cellular Biology ,[SDV.BC.BC]Life Sciences [q-bio]/Cellular Biology/Subcellular Processes [q-bio.SC] ,macromolecular substances ,Biology ,Neurodegenerative ,Article ,Molecular Genetics ,03 medical and health sciences ,Rare Diseases ,medicine ,Genetics ,snRNP ,Molecular genetics ,lcsh:Science ,Molecular Biology ,Actin ,ComputingMilieux_MISCELLANEOUS ,Pediatric ,Multidisciplinary ,Neurosciences ,[SDV.BBM.BM]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Molecular biology ,Spinal muscular atrophy ,Cell Biology ,Biological Sciences ,021001 nanoscience & nanotechnology ,medicine.disease ,Actin cytoskeleton ,Life sciences ,3. Good health ,Cell biology ,nervous system diseases ,030104 developmental biology ,Profilin ,nervous system ,RNA splicing ,Spinal Muscular Atrophy ,Neurological ,biology.protein ,lcsh:Q ,0210 nano-technology ,Cytology ,Cytokinesis - Abstract
Summary Spinal muscular atrophy (SMA) is a devastating motor neuron disorder caused by mutations in the survival motor neuron (SMN) gene. It remains unclear how SMN deficiency leads to the loss of motor neurons. By screening Schizosaccharomyces pombe, we found that the growth defect of an SMN mutant can be alleviated by deletion of the actin-capping protein subunit gene acp1+. We show that SMN mutated cells have splicing defects in the profilin gene, which thus directly hinder actin cytoskeleton homeostasis including endocytosis and cytokinesis. We conclude that deletion of acp1+ in an SMN mutant background compensates for actin cytoskeleton alterations by restoring redistribution of actin monomers between different types of cellular actin networks. Our data reveal a direct correlation between an impaired function of SMN in snRNP assembly and defects in actin dynamics. They also point to important common features in the pathogenic mechanism of SMA and ALS., Graphical Abstract, Highlights • Splicing defects in the profilin gene in an S. pombe SMN mutant • SMN mutant contains excessively polymerized actin • Altered actin dynamics in the SMN mutant hinders endocytosis and cytokinesis • Deletion of the acp1 subunit restores actin dynamics in the SMN mutant, Biological Sciences; Molecular Biology; Molecular Genetics; Cell Biology
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- 2020
21. A motor function for the DEAD-box RNA helicase, Gemin3, in Drosophila.
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Ruben J Cauchi, Kay E Davies, and Ji-Long Liu
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Genetics ,QH426-470 - Abstract
The survival motor neuron (SMN) protein, the determining factor for spinal muscular atrophy (SMA), is complexed with a group of proteins in human cells. Gemin3 is the only RNA helicase in the SMN complex. Here, we report the identification of Drosophila melanogaster Gemin3 and investigate its function in vivo. Like in vertebrates, Gemin3 physically interacts with SMN in Drosophila. Loss of function of gemin3 results in lethality at larval and/or prepupal stages. Before they die, gemin3 mutant larvae exhibit declined mobility and expanded neuromuscular junctions. Expression of a dominant-negative transgene and knockdown of Gemin3 in mesoderm cause lethality. A less severe Gemin3 disruption in developing muscles leads to flightless adults and flight muscle degeneration. Our findings suggest that Drosophila Gemin3 is required for larval development and motor function.
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- 2008
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22. Correction: Genome-Wide Expression Analysis of a Spinal Muscular Atrophy Model: Towards Discovery of New Drug Targets.
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Sheena Lee, Arzu Sayin, Ruben J. Cauchi, Stuart Grice, Howard Burdett, Dilair Baban, and Marcel van den Heuvel
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Medicine ,Science - Published
- 2008
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23. Genome-wide expression analysis of a spinal muscular atrophy model: towards discovery of new drug targets.
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Sheena Lee, Arzu Sayin, Ruben J Cauchi, Stuart Grice, Howard Burdett, Dilair Baban, and Marcel van den Heuvel
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Medicine ,Science - Abstract
Spinal Muscular Atrophy is a recessive genetic disease and affects lower motor neurones and muscle tissue. A single gene is disrupted in SMA: SMN1 activity is abolished but a second copy of the gene (SMN2) provides limited activity. While the SMN protein has been shown to function in the assembly of RNA-protein complexes, it is unclear how the overall reduction in SMN activity specifically results in the neuromuscular phenotypes. Similar to humans, reduced smn activity in the fly causes earliest phenotypes in neuromuscular tissues. To uncover the effects of reduced SMN activity, we have studied gene expression in control and diseased fly tissues using whole genome micro-arrays. A number of gene expression changes are recovered and independently validated. Identified genes show trends in their predicted function: several are consistent with the function of SMN, in addition some uncover novel pathways. This and subsequent genetic analysis in the fly indicates some of the identified genes could be taken for further studies as potential drug targets for SMA and other neuromuscular disorders.
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- 2008
- Full Text
- View/download PDF
24. Extracts from two ubiquitous Mediterranean plants ameliorate cellular and animal models of neurodegenerative proteinopathies
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Stephanie Ghio, Neville Vassallo, Johanna Neuner, Rebecca Cacciottolo, Mario Caruana, Michelle Briffa, Alison J. Gauci, Christelle Marchal, Christophe Cullin, and Ruben J. Cauchi
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0301 basic medicine ,Transgene ,ved/biology.organism_classification_rank.species ,Mutant ,Saccharomyces cerevisiae ,Biology ,Phaeophyta ,Neuroprotection ,03 medical and health sciences ,0302 clinical medicine ,Alzheimer Disease ,medicine ,Animals ,Humans ,Model organism ,Amyloid beta-Peptides ,Plant Extracts ,ved/biology ,General Neuroscience ,Neurodegeneration ,Opuntia ,Neurodegenerative Diseases ,Parkinson Disease ,medicine.disease ,biology.organism_classification ,Phenotype ,Peptide Fragments ,Drosophila melanogaster ,Neuroprotective Agents ,030104 developmental biology ,Biochemistry ,Mutation ,alpha-Synuclein ,030217 neurology & neurosurgery - Abstract
A signature feature of age-related neurodegenerative proteinopathies is the misfolding and aggregation of proteins, typically amyloid-β (Aβ) in Alzheimer's disease (AD) and α-synuclein (α-syn) in Parkinson's disease (PD), into soluble oligomeric structures that are highly neurotoxic. Cellular and animal models that faithfully replicate the hallmark features of these disorders are being increasing exploited to identify disease-modifying compounds. Natural compounds have been identified as a useful source of bioactive molecules with promising neuroprotective capabilities. In the present report, we investigated whether extracts derived from two ubiquitous Mediterranean plants namely, the prickly pear Opuntia ficus-indica (EOFI) and the brown alga Padina pavonica (EPP) alleviate neurodegenerative phenotypes in yeast (Saccharomyces cerevisiae) and fly (Drosophila melanogaster) models of AD and PD. Pre-treatment with EPP or EOFI in the culture medium significantly improved the viability of yeast expressing the Arctic Aβ42 (E22G) mutant. Supplementing food with EOFI or EPP dramatically ameliorated lifespan and behavioural signs of flies with brain-specific expression of wild-type Aβ42 (model of late-onset AD) or the Arctic Aβ42 variant (model of early-onset AD). Additionally, we show that either extract prolonged the survival of a PD fly model based on transgenic expression of the human α-syn A53T mutant. Taken together, our findings suggest that the plant-derived extracts interfere with shared mechanisms of neurodegeneration in AD and PD. This notion is strengthened by evidence demonstrating that EOFI and to a greater extent EPP, while strongly inhibiting the fibrillogenesis of both Aβ42 and α-syn, accumulate remodelled oligomeric aggregates that are less effective at disrupting lipid membrane integrity. Our work therefore opens new avenues for developing therapeutic applications of these natural plant extracts in the treatment of amyloidogenic neurodegenerative disorders.
- Published
- 2017
25. Tau-induced mitochondrial membrane perturbation is dependent upon cardiolipin
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Frits Kamp, Stephanie Ghio, Felix Schmidt, Angelique Camilleri, Mario Caruana, Ruben J. Cauchi, Neville Vassallo, Andrei Leonov, Christian Griesinger, Daniel Weckbecker, Sergey Ryazanov, and Armin Giese
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0301 basic medicine ,Pore complex ,Cardiolipins ,Tau protein ,Biophysics ,tau Proteins ,Mitochondrion ,Biochemistry ,Permeability ,03 medical and health sciences ,chemistry.chemical_compound ,Nanopores ,0302 clinical medicine ,Organelle ,Cardiolipin ,Humans ,Inner mitochondrial membrane ,biology ,Chemistry ,Cell Biology ,Cytosol ,030104 developmental biology ,Mitochondrial permeability transition pore ,Mitochondrial Membranes ,biology.protein ,Protein Multimerization ,030217 neurology & neurosurgery ,Protein Binding - Abstract
Misfolding and aggregate formation by the tau protein has been closely related with neurotoxicity in a large group of human neurodegenerative disorders, which includes Alzheimer's disease. Here, we investigate the membrane-active properties of tau oligomers on mitochondrial membranes, using minimalist in vitro model systems. Thus, exposure of isolated mitochondria to oligomeric tau evoked a disruption of mitochondrial membrane integrity, as evidenced by a combination of organelle swelling, efflux of cytochrome c and loss of the mitochondrial membrane potential. Tau-induced mitochondrial dysfunction occurred independently of the mitochondrial permeability transition (mPT) pore complex. Notably, mitochondria were rescued by pre-incubation with 10-N-nonyl acridine orange (NAO), a molecule that specifically binds cardiolipin (CL), the signature phospholipid of mitochondrial membranes. Additionally, NAO prevented direct binding of tau oligomers to isolated mitochondria. At the same time, tau proteins exhibited high affinity to CL-enriched membranes, whilst permeabilisation of lipid vesicles also strongly correlated with CL content. Intriguingly, using single-channel electrophysiology, we could demonstrate the formation of non-selective ion-conducting tau nanopores exhibiting multilevel conductances in mito-mimetic bilayers. Taken together, the data presented here advances a scenario in which toxic cytosolic entities of tau protein would target mitochondrial organelles by associating with their CL-rich membrane domains, leading to membrane poration and compromised mitochondrial structural integrity.
- Published
- 2019
26. SMN complex member Gemin3 self-interacts and has a functional relationship with ALS-linked proteins TDP-43, FUS and Sod1
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Joanna Ciantar, Rebecca M. Borg, Rebecca Cacciottolo, Ruben J. Cauchi, Neville Vassallo, Rémy Bordonné, and Maia Lanfranco
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Male ,Genotype ,Neuromuscular transmission ,lcsh:Medicine ,Biology ,DNA replication ,Article ,DEAD-box RNA Helicases ,03 medical and health sciences ,0302 clinical medicine ,Superoxide Dismutase-1 ,SMN complex ,C9orf72 ,medicine ,Animals ,Drosophila Proteins ,Humans ,Amyotrophic lateral sclerosis ,RNA, Small Interfering ,lcsh:Science ,Alleles ,030304 developmental biology ,0303 health sciences ,Motor neurons -- Diseases ,Multidisciplinary ,C9orf72 Protein ,Superoxide Dismutase ,lcsh:R ,RNA-Binding Proteins ,Spinal muscular atrophy ,medicine.disease ,SMA ,RNA Helicase A ,3. Good health ,Cell biology ,DNA-Binding Proteins ,Drosophila melanogaster ,Phenotype ,DDX20 ,Flight, Animal ,Epistasis ,lcsh:Q ,Female ,Transcription Factor TFIID ,030217 neurology & neurosurgery - Abstract
The predominant motor neuron disease in infants and adults is spinal muscular atrophy (SMA) and amyotrophic lateral sclerosis (ALS), respectively. SMA is caused by insufficient levels of the Survival Motor Neuron (SMN) protein, which operates as part of the multiprotein SMN complex that includes the DEAD-box RNA helicase Gemin3/DDX20/DP103. C9orf72, SOD1, TDP-43 and FUS are ranked as the four major genes causing familial ALS. Accumulating evidence has revealed a surprising molecular overlap between SMA and ALS. Here, we ask the question of whether Drosophila can also be exploited to study shared pathogenic pathways. Focusing on motor behaviour, muscle mass and survival, we show that disruption of either TBPH/TDP-43 or Caz/FUS enhance defects associated with Gemin3 loss-of-function. Gemin3-associated neuromuscular junction overgrowth was however suppressed. Sod1 depletion had a modifying effect in late adulthood. We also show that Gemin3 self-interacts and Gem3ΔN, a helicase domain deletion mutant, retains the ability to interact with its wild-type counterpart. Importantly, mutant:wild-type dimers are favoured more than wild-type:wild-type dimers. In addition to reinforcing the link between SMA and ALS, further exploration of mechanistic overlaps is now possible in a genetically tractable model organism. Notably, Gemin3 can be elevated to a candidate for modifying motor neuron degeneration., This work was supported by the University of Malta Research Fund to RJC, and the Malta Council for Science & Technology Internationalisation Partnership Award to RJC. RC was supported by the Erasmus+ programme of the EU. ML was supported by an Endeavour Scholarship (Malta), part-financed by the EU – European Social Fund under Operational Programme II – Cohesion Policy 2014–2020, “Investing in human capital to create more opportunities and promote the well-being of society”. RMB was supported by a Bjorn Formosa Scholarship for Advanced Research into ALS/MND funded by the non-profit organisation, ALS Malta Foundation, facilitated by the Research Trust (RIDT) of the University of Malta., peer-reviewed
- Published
- 2019
27. Extract from the Marine Seaweed Padina pavonica Protects Mitochondrial Biomembranes from Damage by Amyloidogenic Peptides
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Maria Ylenia Farrugia, Stephanie Ghio, Angelique Camilleri, Michaela Jakubíčková, Mario Caruana, Neville Vassallo, and Ruben J. Cauchi
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Cell Membrane Permeability ,Lipid Bilayers ,Pharmaceutical Science ,Mitochondrion ,Analytical Chemistry ,0302 clinical medicine ,Membrane proteins ,Drug Discovery ,0303 health sciences ,Padina pavonica seaweed extract ,biology ,Chemistry ,Drug discovery ,Vesicle ,Cytochrome c ,Mitochondria ,mitochondria ,Neuroprotective Agents ,Membrane ,Biochemistry ,Chemistry (miscellaneous) ,Mitochondrial Membranes ,alpha-Synuclein ,Molecular Medicine ,Alzheimer’s disease ,Parkinson's disease -- Case studies ,Amyloid ,Padina pavonica ,Phaeophyta ,Article ,lcsh:QD241-441 ,03 medical and health sciences ,lcsh:Organic chemistry ,Organelle ,Humans ,14. Life underwater ,Alzheimer's disease -- Case studies ,Physical and Theoretical Chemistry ,030304 developmental biology ,Amyloid beta-Peptides ,amyloidogenic proteins ,Amyloidosis -- Diagnosis ,Organic Chemistry ,Seaweed ,biology.organism_classification ,Peptide Fragments ,Parkinson’s disease ,biology.protein ,membrane permeabilization ,030217 neurology & neurosurgery - Abstract
The identification of compounds which protect the double-membrane of mitochondrial organelles from disruption by toxic confomers of amyloid proteins may offer a therapeutic strategy to combat human neurodegenerative diseases. Here, we exploited an extract from the marine brown seaweed Padina pavonica (PPE) as a vital source of natural bioactive compounds to protect mitochondrial membranes against insult by oligomeric aggregates of the amyloidogenic proteins amyloid-β (Aβ), α-synuclein (α-syn) and tau, which are currently considered to be major targets for drug discovery in Alzheimer's disease (AD) and Parkinson's disease (PD). We show that PPE manifested a significant inhibitory effect against swelling of isolated mitochondria exposed to the amyloid oligomers, and attenuated the release of cytochrome c from the mitochondria. Using cardiolipin-enriched synthetic lipid membranes, we also show that dye leakage from fluorophore-loaded vesicles and formation of channel-like pores in planar bilayer membranes are largely prevented by incubating the oligomeric aggregates with PPE. Lastly, we demonstrate that PPE curtails the ability of Aβ42 and α-syn monomers to self-assemble into larger β-aggregate structures, as well as potently disrupts their respective amyloid fibrils. In conclusion, the mito-protective and anti-aggregator biological activities of Padina pavonica extract may be of therapeutic value in neurodegenerative proteinopathies, such as AD and PD., peer-reviewed
- Published
- 2021
28. The multiple lives of DEAD-box RNA helicase DP103/DDX20/Gemin3
- Author
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Ruben J. Cauchi and Frank Curmi
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0301 basic medicine ,DEAD box ,Carcinogenesis ,Gene Expression ,DNA helicases ,Biochemistry ,DEAD-box RNA Helicases ,03 medical and health sciences ,Structure-Activity Relationship ,DEAD Box Protein 20 ,Gene expression ,Transcriptional regulation ,Animals ,Humans ,Gene Silencing ,Motor neurons ,biology ,NF-kappa B ,Helicase ,RNA ,Amyotrophic lateral sclerosis ,Ribonucleoproteins, Small Nuclear ,RNA Helicase A ,Cell biology ,RNA -- Metabolism ,030104 developmental biology ,DDX20 ,biology.protein ,Tumor Suppressor Protein p53 ,Small nuclear ribonucleoprotein ,Signal Transduction - Abstract
Gemin3, also known as DDX20 or DP103, is a DEAD-box RNA helicase which is involved in more than one cellular process. Though RNA unwinding has been determined in vitro, it is surprisingly not required for all of its activities in cellular metabolism. Gemin3 is an essential gene, present in Amoeba and Metazoa. The highly conserved N-terminus hosts the helicase core, formed of the helicase- and DEAD-domains, which, based on crystal structure determination, have key roles in RNA binding. The C-terminus of Gemin3 is highly divergent between species and serves as the interaction site for several accessory factors that could recruit Gemin3 to its target substrates and/or modulate its function. This review article focuses on the known roles of Gemin3, first as a core member of the survival motor neuron (SMN) complex, in small nuclear ribonucleoprotein biogenesis. Although mechanistic details are lacking, a critical function for Gemin3 in this pathway is supported by numerous in vitro and in vivo studies. Gene expression activities of Gemin3 are next underscored, mainly messenger ribonucleoprotein trafficking, gene silencing via microRNA processing, and transcriptional regulation. The involvement of Gemin3 in abnormal cell signal transduction pathways involving p53 and NF-κB is also highlighted. Finally, the clinical implications of Gemin3 deregulation are discussed including links to spinal muscular atrophy, poliomyelitis, amyotrophic lateral sclerosis, and cancer. Impressive progress made over the past two decades since the discovery of Gemin3 bodes well for further work that refines the mechanism(s) underpinning its multiple activities., peer-reviewed
- Published
- 2018
29. Novel interactors of the Drosophila Survival Motor Neuron (SMN) Complex suggest its full conservation
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Maia Lanfranco, Ruben J. Cauchi, Rémy Bordonné, Rebecca M. Borg, Rebecca Cacciottolo, Neville Vassallo, and François Juge
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0301 basic medicine ,Multiprotein complex ,animal diseases ,Biophysics ,Biochemistry ,03 medical and health sciences ,SMN complex ,Structural Biology ,Genetics ,medicine ,Animals ,Drosophila Proteins ,Humans ,Molecular Biology ,Drosophila ,biology ,RNA-Binding Proteins ,SMN Complex Proteins ,Cell Biology ,Anatomy ,Spinal muscular atrophy ,Motor neuron ,biology.organism_classification ,medicine.disease ,nervous system diseases ,030104 developmental biology ,medicine.anatomical_structure ,Drosophila melanogaster ,nervous system ,Neuroscience ,Function (biology) - Abstract
The Spinal Muscular Atrophy disease protein Survival Motor Neuron (SMN) operates as part of a multiprotein complex whose components also include Gemins 2-8 and Unrip. The fruit fly Drosophila melanogaster is thought to have a slightly smaller SMN complex comprised of SMN, Gemin2/3/5 and, possibly, Unrip. Based upon in vivo interaction methods, we have identified novel interacting partners of the Drosophila SMN complex with homologies to Gemin4/6/7/8. The Gemin4 and Gemin8 orthologues are required for neuromuscular function and survival. The Gemin6/7/Unrip module can be recruited via the SMN-associated Gemin8, hence mirroring the human SMN complex architecture. Our findings lead us to propose that an elaborate SMN complex that is typical in metazoans is also present in Drosophila. This article is protected by copyright. All rights reserved.
- Published
- 2017
30. A motor function for the DEAD-box RNA helicase, Gemin3, in Drosophila
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Kay E. Davies, Ruben J. Cauchi, and Ji-Long Liu
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Cancer Research ,DEAD box ,lcsh:QH426-470 ,Physiology/Muscle and Connective Tissue ,DEAD-box RNA Helicases ,Mice ,SMN complex ,DEAD Box Protein 20 ,Physiology/Motor Systems ,Genetics ,medicine ,Animals ,Drosophila Proteins ,Humans ,Proteins -- Physiology ,Transgenes ,Molecular Biology ,Genetics (clinical) ,Ecology, Evolution, Behavior and Systematics ,Loss function ,Motor neurons ,Motor Neurons ,Gene knockdown ,biology ,Neuroscience/Neuronal and Glial Cell Biology ,fungi ,Drosophila melanogaster -- Embryology ,Genetics and Genomics ,Spinal muscular atrophy ,Cell Biology ,Motor neuron ,medicine.disease ,biology.organism_classification ,RNA Helicase A ,Survival of Motor Neuron 1 Protein ,Cell biology ,lcsh:Genetics ,medicine.anatomical_structure ,Drosophila melanogaster ,RNA -- Metabolism ,Drosophila melanogaster -- Genetics ,Larva ,Mutation ,Drosophila ,Cell Biology/Nuclear Structure and Function ,Research Article ,Developmental Biology - Abstract
The survival motor neuron (SMN) protein, the determining factor for spinal muscular atrophy (SMA), is complexed with a group of proteins in human cells. Gemin3 is the only RNA helicase in the SMN complex. Here, we report the identification of Drosophila melanogaster Gemin3 and investigate its function in vivo. Like in vertebrates, Gemin3 physically interacts with SMN in Drosophila. Loss of function of gemin3 results in lethality at larval and/or prepupal stages. Before they die, gemin3 mutant larvae exhibit declined mobility and expanded neuromuscular junctions. Expression of a dominant-negative transgene and knockdown of Gemin3 in mesoderm cause lethality. A less severe Gemin3 disruption in developing muscles leads to flightless adults and flight muscle degeneration. Our findings suggest that Drosophila Gemin3 is required for larval development and motor function., Author Summary The childhood disease spinal muscular atrophy (SMA) has a drastic impact on motor neurons and muscles. The cause has been linked to a deficiency in the survival motor neuron (SMN) protein. SMN interacts with various proteins termed Gemins to form the SMN complex, among which Gemin3 is the only one with an RNA unwinding activity. Here, we study the function of D. melanogaster Gemin3 in the context of development. The association of Gemin3 with SMN, which had been reported previously in humans, is conserved in flies. Loss of Gemin3 resulted in death at larval stages. Before they die, gemin3 mutant flies become sluggish and develop large synapses, which are the contacts between motor neurons and muscles. Disruption of Gemin3 in mesodermal tissues, especially muscles, causes development defects, degeneration of flight muscles, and flies that are unable to fly. This study demonstrates that Gemin3 plays a critical role in fruit fly development, especially in motor function, which raises the question of whether disruption of Gemin3 contributes to SMA.
- Published
- 2016
31. Disruption of snRNP biogenesis factors Tgs1 and pICln induces phenotypes that mirror aspects of SMN-Gemins complex perturbation in Drosophila, providing new insights into spinal muscular atrophy
- Author
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Ruben J. Cauchi, Benji Fenech Salerno, Neville Vassallo, Rebecca M. Borg, and Rémy Bordonné
- Subjects
0301 basic medicine ,wmd ,SMN complex ,Cytoplasm ,snRNP assembly ,Biology ,lcsh:RC321-571 ,03 medical and health sciences ,SMN Complex Proteins ,medicine ,Unrip ,Animals ,Drosophila Proteins ,snRNP ,pICln ,lcsh:Neurosciences. Biological psychiatry. Neuropsychiatry ,SnRNP Biogenesis ,Genetics ,Motor Neurons ,Strap ,Spinal muscular atrophy ,Motor neuron ,SMA ,medicine.disease ,Ribonucleoproteins, Small Nuclear ,Cell biology ,030104 developmental biology ,medicine.anatomical_structure ,Drosophila melanogaster ,Phenotype ,Neurology ,Drosophila Protein - Abstract
The neuromuscular disorder, spinal muscular atrophy (SMA), results from insufficient levels of the survival motor neuron (SMN) protein. Together with Gemins 2-8 and Unrip, SMN forms the large macromolecular SMN-Gemins complex, which is known to be indispensable for chaperoning the assembly of spliceosomal small nuclear ribonucleoproteins (snRNPs). It remains unclear whether disruption of this function is responsible for the selective neuromuscular degeneration in SMA. In the present study, we first show that loss of wmd, the Drosophila Unrip orthologue, has a negative impact on the motor system. However, due to lack of a functional relationship between wmd/Unrip and Gemin3, it is likely that Unrip joined the SMN-Gemins complex only recently in evolution. Second, we uncover that disruption of either Tgs1 or pICln, two cardinal players in snRNP biogenesis, results in viability and motor phenotypes that closely resemble those previously uncovered on loss of the constituent members of the SMN-Gemins complex. Interestingly, overexpression of both factors leads to motor dysfunction in Drosophila, a situation analogous to that of Gemin2. Toxicity is conserved in the yeast S. pombe where pICln overexpression induces a surplus of Sm proteins in the cytoplasm, indicating that a block in snRNP biogenesis is partly responsible for this phenotype. Importantly, we show a strong functional relationship and a physical interaction between Gemin3 and either Tgs1 or pICln. We propose that snRNP biogenesis is the pathway connecting the SMN-Gemins complex to a functional neuromuscular system, and its disturbance most likely leads to the motor dysfunction that is typical in SMA.
- Published
- 2015
32. Genetic Interactions between the Members of the SMN-Gemins Complex in Drosophila
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Ruben J. Cauchi, Rebecca M. Borg, Rémy Bordonné, Neville Vassallo, University of Malta [Malta], Institut de Génétique Moléculaire de Montpellier (IGMM), and Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)
- Subjects
Cytoplasm ,animal diseases ,Mutant ,lcsh:Medicine ,Nerve Tissue Proteins ,Biology ,medicine.disease_cause ,Muscular Atrophy, Spinal ,SMN Complex Proteins ,Schizosaccharomyces ,medicine ,Animals ,Drosophila Proteins ,snRNP ,[SDV.BBM]Life Sciences [q-bio]/Biochemistry, Molecular Biology ,lcsh:Science ,Motor neurons ,Motor Neurons ,Genetics ,Mutation ,Multidisciplinary ,Muscles ,lcsh:R ,RNA-Binding Proteins ,Correction ,Spinal muscular atrophy ,Motor neuron ,Neuromuscular diseases -- Case studies ,Ribonucleoproteins, Small Nuclear ,medicine.disease ,biology.organism_classification ,Up-Regulation ,nervous system diseases ,Nucleoproteins ,medicine.anatomical_structure ,nervous system ,Spliceosomes ,Drosophila ,lcsh:Q ,Drosophila melanogaster ,Drosophila Protein ,Research Article - Abstract
The SMN-Gemins complex is composed of Gemins 2-8, Unrip and the survival motor neuron (SMN) protein. Limiting levels of SMN result in the neuromuscular disorder, spinal muscular atrophy (SMA), which is presently untreatable. The most-documented function of the SMN-Gemins complex concerns the assembly of spliceosomal small nuclear ribonucleoproteins (snRNPs). Despite multiple genetic studies, the Gemin proteins have not been identified as prominent modifiers of SMN-associated mutant phenotypes. In the present report, we make use of the Drosophila model organism to investigate whether viability and motor phenotypes associated with a hypomorphic Gemin3 mutant are enhanced by changes in the levels of SMN, Gemin2 and Gemin5 brought about by various genetic manipulations. We show a modifier effect by all three members of the minimalistic fly SMN-Gemins complex within the muscle compartment of the motor unit. Interestingly, muscle-specific overexpression of Gemin2 was by itself sufficient to depress normal motor function and its enhanced upregulation in all tissues leads to a decline in fly viability. The toxicity associated with increased Gemin2 levels is conserved in the yeast S. pombe in which we find that the cytoplasmic retention of Sm proteins, likely reflecting a block in the snRNP assembly pathway, is a contributing factor. We propose that a disruption in the normal stoichiometry of the SMN-Gemins complex depresses its function with consequences that are detrimental to the motor system., peer-reviewed
- Published
- 2015
33. The Fly as a Model for Neurodegenerative Diseases: Is It Worth the Jump?
- Author
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Ruben J. Cauchi and Marcel van den Heuvel
- Subjects
RNA metabolism ,business.industry ,Human life ,Neurodegeneration ,Neurodegenerative Diseases ,medicine.disease ,Neuroprotection ,Aberrant protein ,Disease Models, Animal ,Drosophila melanogaster ,Neuropharmacology ,Neurology ,medicine ,Animals ,Humans ,RNA ,Neurology (clinical) ,business ,Neuroscience ,Fragile X-associated tremor/ataxia syndrome - Abstract
Neurodegenerative diseases are responsible for agonizing symptoms that take their toll on the fragile human life. Aberrant protein processing and accumulation are considered to be the culprits of many classical neurodegenerative diseases such as Alzheimer’s disease, tauopathies, Parkinson’s disease, amyotrophic lateral sclerosis, hereditary spastic paraplegia and various polyglutamine diseases. However, recently it has been shown that toxic RNA species or disruption of RNA processing and metabolism may be partly to blame as clearly illustrated in spinal muscular atrophy, spinocerebellar ataxia 8 and fragile X-associated tremor/ataxia syndrome. At the dawn of the twenty-first century, the fruit fly or Drosophila melanogaster has taken its place at the forefront of an uphill struggle to unveil the molecular and cellular pathophysiology of both protein- and RNA-induced neurodegeneration, as well as discovery of novel drug targets. We review here the various fly models of neurodegenerative conditions, and summarise the novel insights that the fly has contributed to the field of neuroprotection and neurodegeneration.
- Published
- 2006
34. Gem depletion: amyotrophic lateral sclerosis and spinal muscular atrophy crossover
- Author
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Ruben J. Cauchi
- Subjects
Spliceosome ,Biology ,Muscular Atrophy, Spinal ,Degenerative disease ,Physiology (medical) ,medicine ,Animals ,Humans ,Pharmacology (medical) ,snRNP ,Amyotrophic lateral sclerosis ,Review Articles ,Pharmacology ,Amyotrophic Lateral Sclerosis ,SMN Complex Proteins ,Spinal muscular atrophy ,Motor neuron ,medicine.disease ,SMA ,Ribonucleoproteins, Small Nuclear ,Psychiatry and Mental health ,medicine.anatomical_structure ,Cajal body ,nervous system ,Spliceosomes ,Neuroscience - Abstract
The determining factor of spinal muscular atrophy (SMA), the most common motor neuron degenerative disease of childhood, is the survival motor neuron (SMN) protein. SMN and its Gemin associates form a complex that is indispensible for the biogenesis of small nuclear ribonucleoproteins (snRNPs), which constitute the building blocks of spliceosomes. It is as yet unclear whether a decreased capacity of SMN in snRNP assembly, and, hence, transcriptome abnormalities, account for the specific neuromuscular phenotype in SMA. Across metazoa, the SMN-Gemins complex concentrates in multiple nuclear gems that frequently neighbour or overlap Cajal bodies. The number of gems has long been known to be a faithful indicator of SMN levels, which are linked to SMA severity. Intriguingly, a flurry of recent studies have revealed that depletion of this nuclear structure is also a signature feature of amyotrophic lateral sclerosis (ALS), the most common adult-onset motor neuron disease. This review discusses such a surprising crossover in addition to highlighting the most recent work on the intricate world of spliceosome building, which seems to be at the heart of motor neuron physiology and survival.
- Published
- 2013
35. The Gemin Associates of Survival Motor Neuron Are Required for Motor Function in Drosophila
- Author
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Ruben J. Cauchi and Rebecca M. Borg
- Subjects
Neuromuscular transmission ,lcsh:Medicine ,Animals, Genetically Modified ,DEAD-box RNA Helicases ,Immunoenzyme Techniques ,RNA interference ,SMN complex ,Drosophila Proteins ,Transgenes ,Genes -- Research ,lcsh:Science ,Genes, Dominant ,Genetics ,Motor Neurons ,Multidisciplinary ,Behavior, Animal ,Drosophila Melanogaster ,Gene Expression Regulation, Developmental ,SMN Complex Proteins ,Animal Models ,Cell biology ,medicine.anatomical_structure ,Drosophila melanogaster ,Larva ,Drosophila -- Genetics ,Drosophila Protein ,Small nuclear ribonucleoprotein ,Research Article ,Neurophysiology ,Biology ,Motor Activity ,Model Organisms ,Genetic Mutation ,medicine ,Animals ,Humans ,snRNP ,Gene Networks ,Muscle, Skeletal ,Motor Systems ,lcsh:R ,Mutation Types ,Spinal muscular atrophy ,Motor neuron ,medicine.disease ,Mutational Hypotheses ,Flight, Animal ,Mutation ,lcsh:Q ,Gene expression ,Gene Function ,Neuroscience - Abstract
Membership of the survival motor neuron (SMN) complex extends to nine factors, including the SMN protein, the product of the spinal muscular atrophy (SMA) disease gene, Gemins 2–8 and Unrip. The best-characterised function of this macromolecular machine is the assembly of the Sm-class of uridine-rich small nuclear ribonucleoprotein (snRNP) particles and each SMN complex member has a key role during this process. So far, however, only little is known about the function of the individual Gemin components in vivo. Here, we make use of the Drosophila model organism to uncover loss-of-function phenotypes of Gemin2, Gemin3 and Gemin5, which together with SMN form the minimalistic fly SMN complex. We show that ectopic overexpression of the dead helicase Gem3DN mutant or knockdown of Gemin3 result in similar motor phenotypes, when restricted to muscle, and in combination cause lethality, hence suggesting that Gem3DN overexpression mimics a loss-of-function. Based on the localisation pattern of Gem3DN, we predict that the nucleus is the primary site of the antimorphic or dominant-negative mechanism of Gem3DN-mediated interference. Interestingly, phenotypes induced by human SMN overexpression in Drosophila exhibit similarities to those induced by overexpression of Gem3DN. Through enhanced knockdown we also uncover a requirement of Gemin2, Gemin3 and Gemin5 for viability and motor behaviour, including locomotion as well as flight, in muscle. Notably, in the case of Gemin3 and Gemin5, such function also depends on adequate levels of the respective protein in neurons. Overall, these findings lead us to speculate that absence of any one member is sufficient to arrest the SMN-Gemins complex function in a nucleocentric pathway, which is critical for motor function in vivo., peer-reviewed
- Published
- 2013
36. Conserved requirement for DEAD-box RNA helicase Gemin3 in Drosophila oogenesis
- Author
-
Ruben J. Cauchi
- Subjects
Male ,DEAD box ,Germline ,Survival of motor neurons ,Short Report ,lcsh:Medicine ,Coiled Bodies ,Ovaries -- Physiology ,Biology ,General Biochemistry, Genetics and Molecular Biology ,Drosophila ,DEAD-box RNA Helicases ,Oogenesis ,Germ cells ,Animals ,Drosophila Proteins ,Oogenesis -- Physiology ,Drosophila -- Molecular genetics ,snRNP ,lcsh:Science (General) ,lcsh:QH301-705.5 ,Germ-Line Mutation ,Ribonucleoprotein ,Medicine(all) ,Genetics ,Microscopy, Confocal ,Biochemistry, Genetics and Molecular Biology(all) ,lcsh:R ,Gemin3 ,General Medicine ,Spinal muscular atrophy ,Ribonucleoproteins, Small Nuclear ,RNA Helicase A ,Chromatin ,Chromosomes, Insect ,RNA silencing ,Drosophila melanogaster ,Cajal body ,lcsh:Biology (General) ,Oocytes ,Female ,Motor neurons -- Research ,Drosophila Protein ,Small nuclear RNA ,lcsh:Q1-390 - Abstract
Background: DEAD-box RNA helicase Gemin3 is an essential protein since its deficiency is lethal in both vertebrates and invertebrates. In addition to playing a role in transcriptional regulation and RNA silencing, as a core member of the SMN (survival of motor neurons) complex, Gemin3 is required for the biogenesis of spliceosomal snRNPs (small nuclear ribonucleoproteins), and axonal mRNA metabolism. Studies in the mouse and C. elegans revealed that loss of Gemin3 function has a negative impact on ovarian physiology and development. Findings. This work reports on the generation and characterisation of gemin3 mutant germline clones in Drosophila adult females. Gemin3 was found to be required for the completion of oogenesis and its loss led to egg polarity defects, oocyte mislocalisation, and abnormal chromosome morphology. Canonical Cajal bodies were absent in the majority of gemin3 mutant egg chambers and histone locus bodies displayed an atypical morphology. snRNP distribution was perturbed so that on gemin3 loss, snRNP cytoplasmic aggregates (U bodies) were only visible in wild type. Conclusions: These findings establish a conserved requirement for Gemin3 in Drosophila oogenesis. Furthermore, in view of the similarity to the phenotypes described previously in smn mutant germ cells, the present results confirm the close functional relationship between SMN and Gemin3 on a cellular level., peer-reviewed
- Published
- 2012
37. Genetic animal models of Tourette syndrome : the long and winding road from lab to clinic
- Author
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Zsanett Tárnok and Ruben J. Cauchi
- Subjects
medicine.medical_specialty ,Neurology ,Tics ,Tic disorders ,General Neuroscience ,Histamine -- Physiological effect ,Disease ,Neurobehavioral disorders ,medicine.disease ,Tourette syndrome ,SLITRK1 ,Drosophila melanogaster ,Tourette syndrome -- Pathogenesis ,Genetic model ,medicine ,Obsessive-compulsive disorder ,Anxiety ,medicine.symptom ,Psychology ,Neuroscience ,Gene knockout - Abstract
Tourette syndrome (TS) is a disabling neuropsychiatric disorder characterised by persistent motor and vocal tics. TS is a highly comorbid state, hence, patients might experience anxiety, obsessions, compulsions, sleep abnormalities, depression, emotional liability, learning problems, and attention deficits in addition to tics. In spite of its complex heterogeneous genetic aetiology, recent studies highlighted a strong link between TS and genetic lesions in the HDC (L-histidine decarboxylase) gene, which encodes the enzyme that synthetises histamine, and the SLITRK1 (SLIT and TRK-like family member 1) gene, which encodes a transmembrane protein that was found to regulate neurite outgrowth. In addition to validating the contribution of a specific genetic aberration to the development of a particular pathology, animal models are crucial to dissect the function of disease-linked proteins, expose disease pathways through examination of genetic modifiers and discover as well as assess therapeutic strategies. Mice with a knockout of either Hdc or Slitrk1 exhibit anxiety and those lacking Hdc, display dopamine agonist-triggered stereotypic movements. However, the mouse knockouts do not spontaneously display tics, which are recognised as the hallmark of TS. In this review, we explore the features of the present genetic animal models of TS and identify reasons for their poor resemblance to the human condition. Importantly, we highlight ways forward aimed at developing a valuable genetic model of TS or a model that has good predictive validity in developing therapeutic drugs for the treatment of tics, hence potentially accelerating the arduous journey from lab to clinic., peer-reviewed
- Published
- 2012
38. Gem formation upon constitutive Gemin3 overexpression in Drosophila
- Author
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Ruben J. Cauchi
- Subjects
Cytoplasm ,endocrine system diseases ,Transgene ,Fluorescent Antibody Technique ,Coiled Bodies ,DEAD-box RNA Helicases ,SMN complex ,medicine ,Animals ,Drosophila Proteins ,Ribonucleoprotein ,Genetics ,Cell Nucleus ,biology ,Epidermis (botany) ,digestive, oral, and skin physiology ,SMN Complex Proteins ,Cell Biology ,General Medicine ,Spinal muscular atrophy ,biology.organism_classification ,medicine.disease ,Cell biology ,nervous system ,Cajal body ,Larva ,Drosophila ,Drosophila melanogaster - Abstract
Gems or ‘Gemini of Cajal bodies’ are spherical nuclear aggregates of SMN (survival of motor neurons) complexes that frequently overlap Cajal bodies. Although described and characterized in mammalian tissues, gems have not been reported in invertebrates. Stimulation of gem formation in the fruitfly Drosophila melanogaster was investigated through the constitutive overexpression of a fluorescently tagged transgene of a DEAD-box SMN complex member, Gemin3, in wild-type tissues. Although expression was predominantly cytoplasmic in the larval brain cells, Gemin3 was found enriched in multiple discrete bright foci in the nuclei of several tissues including epidermis, muscle and gut. Similar to their mammalian counterparts, Drosophila gems contained endogenous SMN and at times overlapped with Cajal bodies. These findings support the hypothesis that gems are storage sites for excess nuclear SMN complexes and their frequent association with Cajal bodies might imply recruitment for nuclear ribonucleoprotein assembly reactions.
- Published
- 2011
39. SMN and Gemins: 'we are family' … or are we?: insights into the partnership between Gemins and the spinal muscular atrophy disease protein SMN
- Author
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Ruben J. Cauchi
- Subjects
Spliceosome ,Neuromuscular disease ,animal diseases ,Coiled Bodies ,Disease ,Biology ,General Biochemistry, Genetics and Molecular Biology ,Muscular Atrophy, Spinal ,SMN complex ,medicine ,Animals ,Humans ,Muscle, Skeletal ,Ribonucleoprotein ,Motor Neurons ,SMN Complex Proteins ,Anatomy ,Spinal muscular atrophy ,Motor neuron ,medicine.disease ,SMA ,Ribonucleoproteins, Small Nuclear ,nervous system diseases ,medicine.anatomical_structure ,nervous system ,Spliceosomes ,Neuroscience - Abstract
Gemins 2-8 and Unr-interacting protein (UNRIP) are intimate partners of the survival motor neuron (SMN) protein, which is the determining factor for the neuromuscular disorder spinal muscular atrophy (SMA). The most documented role of SMN, Gemins and UNRIP occurs within the large macromolecular SMN complex and involves the cytoplasmic assembly of spliceosomal uridine-rich small nuclear ribonucleoproteins (UsnRNPs), a housekeeping process critical in all cells. Several reports detailing alternative functions for SMN in either motor neurons or skeletal muscles may, however, hold the answer to the extreme neuromuscular tissue specificity observed in SMA. Recent discoveries indicate that collaboration between SMN and Gemins also extends to these non-canonical functions, hence raising the possibility that mutations in Gemin genes may be the cause of unlinked neuromuscular hereditary syndromes. This review evaluates the functions of Gemins and UNRIP inside the SMN complex and discusses whether these less notorious SMN complex members are capable of acting independently of SMN.
- Published
- 2010
40. Drosophila SMN complex proteins Gemin2, Gemin3, and Gemin5 are components of U bodies
- Author
-
Ji-Long Liu, Luis Sanchez-Pulido, and Ruben J. Cauchi
- Subjects
Genetics ,In silico ,RNA ,SMN Complex Proteins ,Cell Biology ,Biology ,Ribonucleoproteins, Small Nuclear ,DEAD-box RNA Helicases ,Drosophila melanogaster ,medicine.anatomical_structure ,Cytoplasm ,P-bodies ,medicine ,Animals ,Drosophila Proteins ,Humans ,Female ,snRNP ,Nucleus ,Phylogeny ,SnRNP Biogenesis - Abstract
Uridine-rich small nuclear ribonucleoproteins (U snRNPs) play key roles in pre-mRNA processing in the nucleus. The assembly of most U snRNPs takes place in the cytoplasm and is facilitated by the survival motor neuron (SMN) complex. Discrete cytoplasmic RNA granules called U bodies have been proposed to be specific sites for snRNP assembly because they contain U snRNPs and SMN. U bodies invariably associate with P bodies, which are involved in mRNA decay and translational control. However, it remains unknown whether other SMN complex proteins also localise to U bodies. In Drosophila there are four SMN complex proteins, namely SMN, Gemin2/CG10419, Gemin3 and Gemin5/Rigor mortis. Drosophila Gemin3 was originally identified as the Drosophila orthologue of human and yeast Dhh1, a component of P bodies. Through an in silico analysis of the DEAD-box RNA helicases we confirmed that Gemin3 is the bona fide Drosophila orthologue of vertebrate Gemin3 whereas the Drosophila orthologue of Dhh1 is Me31B. We then made use of the Drosophila egg chamber as a model system to study the subcellular distribution of the Gemin proteins as well as Me31B. Our cytological investigations show that Gemin2, Gemin3 and Gemin5 colocalise with SMN in U bodies. Although they are excluded from P bodies, as components of U bodies, Gemin2, Gemin3 and Gemin5 are consistently found associated with P bodies, wherein Me31B resides. In addition to a role in snRNP biogenesis, SMN complexes residing in U bodies may also be involved in mRNP assembly and/or transport.
- Published
- 2010
41. Contents Vol. 3, 2006
- Author
-
Nikolaos K. Robakis, Lisette Arnaud, Georgios M. Hadjigeorgiou, O. Hellström, V. Gourbali, James D. Hardy, G. Xiromerisiou, Alexandros Papadimitriou, Jaime Duckworth, J. Eerola, M. Axel Wollmer, Andreas Papassotiropoulos, Kelly S. Benke, J. R. Gibbs, Lon R. White, Roger M. Nitsch, C. Chen, Lauren Marlowe, Rita Peila, Ruben J. Cauchi, Amanda J. Myers, P.J. Tienari, Yih-Ru Wu, AB Singleton, H.C. Fung, Maria E. Figueiredo-Pereira, John Hardy, Lenore J. Launer, Christoph Hock, and Marcel van den Heuvel
- Subjects
Neurology ,Neurology (clinical) - Published
- 2006
42. Subject Index Vol. 3, 2006
- Author
-
James D. Hardy, Georgios M. Hadjigeorgiou, O. Hellström, G. Xiromerisiou, J. Eerola, Nikolaos K. Robakis, Alexandros Papadimitriou, Lon R. White, Andreas Papassotiropoulos, John Hardy, Lisette Arnaud, Lenore J. Launer, Christoph Hock, Rita Peila, Ruben J. Cauchi, Kelly S. Benke, Yih-Ru Wu, J. R. Gibbs, AB Singleton, M. Axel Wollmer, Jaime Duckworth, Marcel van den Heuvel, Lauren Marlowe, H.C. Fung, V. Gourbali, Roger M. Nitsch, C. Chen, Amanda J. Myers, P.J. Tienari, and Maria E. Figueiredo-Pereira
- Subjects
Index (economics) ,Neurology ,Statistics ,Subject (documents) ,Neurology (clinical) ,Mathematics - Published
- 2006
43. SCFD1 in amyotrophic lateral sclerosis: reconciling a genetic association with in vivo functional analysis.
- Author
-
Cauchi, Ruben J.
- Published
- 2024
- Full Text
- View/download PDF
44. Reduced levels of ALS gene DCTN1 induce motor defects in Drosophila.
- Author
-
Borg, Rebecca, Herrera, Paul, Purkiss, Angie, Cacciottolo, Rebecca, and Cauchi, Ruben J.
- Subjects
AMYOTROPHIC lateral sclerosis ,DROSOPHILA ,SYNAPSES ,NEUROMUSCULAR diseases ,MOLECULAR motor proteins ,MYONEURAL junction - Abstract
Amyotrophic lateral sclerosis (ALS) is a rapidly progressive neuromuscular disease that has a strong genetic component. Deleterious variants in the DCTN1 gene are known to be a cause of ALS in diverse populations. DCTN1 encodes the p150 subunit of the molecular motor dynactin which is a key player in the bidirectional transport of cargos within cells. Whether DCTN1 mutations lead to the disease through either a gain or loss of function mechanism remains unresolved. Moreover, the contribution of non-neuronal cell types, especially muscle tissue, to ALS phenotypes in DCTN1 carriers is unknown. Here we show that gene silencing of Dctn1, the Drosophila main orthologue of DCTN1, either in neurons or muscles is sufficient to cause climbing and flight defects in adult flies. We also identify Dred, a protein with high homology to Drosophila Dctn1 and human DCTN1, that on loss of function also leads to motoric impairments. A global reduction of Dctn1 induced a significant reduction in the mobility of larvae and neuromuscular junction (NMJ) deficits prior to death at the pupal stage. RNAseq and transcriptome profiling revealed splicing alterations in genes required for synapse organisation and function, which may explain the observed motor dysfunction and synaptic defects downstream of Dctn1 ablation. Our findings support the possibility that loss of DCTN1 function can lead to ALS and underscore an important requirement for DCTN1 in muscle in addition to neurons. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
45. Genome-wide study of DNA methylation shows alterations in metabolic, inflammatory, and cholesterol pathways in ALS.
- Author
-
Hop, Paul J., Zwamborn, Ramona A.J., Hannon, Eilis, Shireby, Gemma L., Nabais, Marta F., Walker, Emma M., van Rheenen, Wouter, van Vugt, Joke J.F.A., Dekker, Annelot M., Westeneng, Henk-Jan, Tazelaar, Gijs H.P., van Eijk, Kristel R., Moisse, Matthieu, Baird, Denis, Al Khleifat, Ahmad, Iacoangeli, Alfredo, Ticozzi, Nicola, Ratti, Antonia, Cooper-Knock, Jonathan, and Morrison, Karen E.
- Subjects
DNA methylation ,CHOLESTEROL metabolism ,HDL cholesterol ,AMYOTROPHIC lateral sclerosis ,LEUCOCYTES ,GENOME-wide association studies ,DNA methyltransferases - Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease with an estimated heritability between 40 and 50%. DNA methylation patterns can serve as proxies of (past) exposures and disease progression, as well as providing a potential mechanism that mediates genetic or environmental risk. Here, we present a blood-based epigenome-wide association study meta-analysis in 9706 samples passing stringent quality control (6763 patients, 2943 controls). We identified a total of 45 differentially methylated positions (DMPs) annotated to 42 genes, which are enriched for pathways and traits related to metabolism, cholesterol biosynthesis, and immunity. We then tested 39 DNA methylation–based proxies of putative ALS risk factors and found that high-density lipoprotein cholesterol, body mass index, white blood cell proportions, and alcohol intake were independently associated with ALS. Integration of these results with our latest genome-wide association study showed that cholesterol biosynthesis was potentially causally related to ALS. Last, DNA methylation at several DMPs and blood cell proportion estimates derived from DNA methylation data were associated with survival rate in patients, suggesting that they might represent indicators of underlying disease processes potentially amenable to therapeutic interventions. Understanding ALS epigenetics: Neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS), have been associated to epigenetic modifications, suggesting that identification of specific epigenetic patterns could provide insights into disease pathophysiology and help the identification of potential pharmacological targets. Here, Hop et al. analyzed DNA methylation pattern, one of the most characterized epigenetic modifications, in almost 10,000 individuals with ALS and controls and identified 45 differentially methylated positions (DMPs) annotated to 42 genes. The changes involved genes associated to metabolic and inflammatory pathways, and the authors identified several DMPs associated with disease progression in their cohort. The results will help the identification of disease-relevant mechanisms that could be targeted to block or delay ALS progression. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
46. Occupation and amyotrophic lateral sclerosis risk: a case-control study in the isolated island population of Malta.
- Author
-
Farrugia Wismayer, Maia, Borg, Rebecca, Farrugia Wismayer, Andrew, Bonavia, Karl, Vella, Malcolm, Pace, Adrian, Vassallo, Neville, and Cauchi, Ruben J.
- Subjects
AMYOTROPHIC lateral sclerosis ,CASE-control method ,ADULTS ,INDUSTRIAL arts ,PHYSICAL activity - Abstract
Objective: Amyotrophic lateral sclerosis (ALS) is a mostly sporadic neurodegenerative disease. The role of environmental factors has been extensively investigated but associations remain controversial. Considering that a substantial proportion of adult life is spent at work, identifying occupations and work-related exposures is considered an effective way to detect factors that increase ALS risk. This process may be further facilitated in population isolates due to environmental and genetic homogeneity. Our study investigated occupations and occupational exposures potentially associated with ALS risk in the isolated island population of Malta, using a case-control study design. Methods: Patients with ALS and randomly identified matched controls (1:1) were recruited throughout a four-year window, from 2017 through 2020. Data on educational level, residence, main occupation, smoking, and alcohol history were collected. Results: We found that compared to controls (44.4%), a higher percentage (73.7%) of ALS patients reported a blue-collar job as their main occupation (OR 2.04, 95% CI 1.2–3.72; p = 0.0072). Through regression analysis, craft and related trades occupations such as carpentry and construction (ISCO-08 major group 7), were found to be positively associated with ALS, with patients in this occupational category found to be more prone to develop bulbar-onset ALS (p = 0.0297). Overall, patients with ALS reported a significantly higher exposure to work-related strenuous physical activity (OR 2.35, 95% CI 1.53–3.59; p = 0.0002). Conclusion: Our findings suggest that manual workers particularly those working in the carpentry and construction industries have an increased ALS risk, possibly due to a history of intense or sustained physical activity. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
47. Toxic oligomers of the amyloidogenic HypF-N protein form pores in mitochondrial membranes.
- Author
-
Farrugia, Maria Ylenia, Caruana, Mario, Ghio, Stephanie, Camilleri, Angelique, Farrugia, Claude, Cauchi, Ruben J., Cappelli, Sara, Chiti, Fabrizio, and Vassallo, Neville
- Subjects
MITOCHONDRIAL membranes ,OLIGOMERS ,IMMUNE response ,IMMUNOLOGY ,CLINICAL trials - Abstract
Studies on the amyloidogenic N-terminal domain of the E. coli HypF protein (HypF-N) have contributed significantly to a detailed understanding of the pathogenic mechanisms in neurodegenerative diseases characterised by the formation of misfolded oligomers, by proteins such as amyloid-β, α-synuclein and tau. Given that both cell membranes and mitochondria are increasingly recognised as key targets of oligomer toxicity, we investigated the damaging effects of aggregates of HypF-N on mitochondrial membranes. Essentially, we found that HypF-N oligomers characterised by high surface hydrophobicity (type A) were able to trigger a robust permeabilisation of mito-mimetic liposomes possessing cardiolipin-rich membranes and dysfunction of isolated mitochondria, as demonstrated by a combination of mitochondrial shrinking, lowering of mitochondrial membrane potential and cytochrome c release. Furthermore, using single-channel electrophysiology recordings we obtained evidence that the type A aggregates induced currents reflecting formation of ion-conducting pores in mito-mimetic planar phospholipid bilayers, with multi-level conductances ranging in the hundreds of pS at negative membrane voltages. Conversely, HypF-N oligomers with low surface hydrophobicity (type B) could not permeabilise or porate mitochondrial membranes. These results suggest an inherent toxicity of membrane-active aggregates of amyloid-forming proteins to mitochondria, and that targeting of oligomer-mitochondrial membrane interactions might therefore afford protection against such damage. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
48. Negative cooperativity between Gemin2 and RNA provides insights into RNA selection and the SMN complex's release in snRNP assembly.
- Author
-
Yi, Hongfei, Mu, Li, Shen, Congcong, Kong, Xi, Wang, Yingzhi, Hou, Yan, and Zhang, Rundong
- Published
- 2020
- Full Text
- View/download PDF
49. The multiple lives of DEAD-box RNA helicase DP103/DDX20/Gemin3.
- Author
-
Curmi, Frank and Cauchi, Ruben J.
- Subjects
RNA helicase ,CELL metabolism ,CRYSTAL structure ,MOTOR neurons ,ORIGIN of life ,GENE expression ,GENE silencing - Abstract
Gemin3, also known as DDX20 or DP103, is a DEAD-box RNA helicase which is involved in more than one cellular process. Though RNA unwinding has been determined in vitro, it is surprisingly not required for all of its activities in cellular metabolism. Gemin3 is an essential gene, present in Amoeba and Metazoa. The highly conserved N-terminus hosts the helicase core, formed of the helicase- and DEAD-domains, which, based on crystal structure determination, have key roles in RNA binding. The C-terminus of Gemin3 is highly divergent between species and serves as the interaction site for several accessory factors that could recruit Gemin3 to its target substrates and/or modulate its function. This review article focuses on the known roles of Gemin3, first as a core member of the survival motor neuron (SMN) complex, in small nuclear ribonucleoprotein biogenesis. Although mechanistic details are lacking, a critical function for Gemin3 in this pathway is supported by numerous in vitro and in vivo studies. Gene expression activities of Gemin3 are next underscored, mainly messenger ribonucleoprotein trafficking, gene silencing via microRNA processing, and transcriptional regulation. The involvement of Gemin3 in abnormal cell signal transduction pathways involving p53 and NF-kB is also highlighted. Finally, the clinical implications of Gemin3 deregulation are discussed including links to spinal muscular atrophy, poliomyelitis, amyotrophic lateral sclerosis, and cancer. Impressive progress made over the past two decades since the discovery of Gemin3 bodes well for further work that refines the mechanism(s) underpinning its multiple activities. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
50. Novel interactors of the Drosophila Survival Motor Neuron (SMN) Complex suggest its full conservation.
- Author
-
Lanfranco, Maia, Cacciottolo, Rebecca, Borg, Rebecca M., Vassallo, Neville, Juge, François, Bordonné, Rémy, and Cauchi, Ruben J.
- Subjects
MOTOR neurons ,PROTEIN-protein interactions ,NEURONS ,HOMOLOGOUS chromosomes ,CHROMOSOMES - Abstract
The Spinal Muscular Atrophy disease protein Survival Motor Neuron ( SMN) operates as part of a multiprotein complex whose components also include Gemins 2-8 and Unrip. The fruit fly Drosophila melanogaster is thought to have a slightly smaller SMN complex comprised of SMN, Gemin2/3/5 and, possibly, Unrip. Based upon in vivo interaction methods, we have identified novel interacting partners of the Drosophila SMN complex with homologies to Gemin4/6/7/8. The Gemin4 and Gemin8 orthologues are required for neuromuscular function and survival. The Gemin6/7/Unrip module can be recruited via the SMN-associated Gemin8, hence mirroring the human SMN complex architecture. Our findings lead us to propose that an elaborate SMN complex that is typical in metazoans is also present in Drosophila. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
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