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Many lines of evidence have highlighted the role played by heterogeneous nuclear ribonucleoproteins in amyotrophic lateral sclerosis. In this study, we have aimed to identify transcripts co-regulated by TAR DNA-binding protein 43 kDa and highly conserved heterogeneous nuclear ribonucleoproteins which have been previously shown to regulate TAR DNA-binding protein 43 kDa toxicity (deleted in azoospermia-associated protein 1, heterogeneous nuclear ribonucleoprotein -Q, -D, -K and -U). Using the transcriptome analyses, we have uncovered that Nitric Oxide Synthase 1 Adaptor Protein mRNA is a direct TAR DNA-binding protein 43 kDa target, and in flies, its modulation alone can rescue TAR DNA-binding protein 43 kDa pathology. In primary mouse cortical neurons, we show that TAR DNA-binding protein 43 kDa mediated downregulation of Nitric Oxide Synthase 1 Adaptor Protein expression strongly affects the NMDA-receptor signalling pathway. In human patients, the downregulation of Nitric Oxide Synthase 1 Adaptor Protein mRNA strongly correlates with TAR DNA-binding protein 43 kDa proteinopathy as measured by cryptic Stathmin-2 and Unc-13 homolog A cryptic exon inclusion. Overall, our results demonstrate that Nitric Oxide Synthase 1 Adaptor Protein may represent a novel disease-relevant gene, potentially suitable for the development of new therapeutic strategies.

Amyotrophic lateral sclerosis (ALS) is a heterogenous neurodegenerative disorder that affects motor neurons and voluntary muscle control1. ALS heterogeneity includes the age of manifestation, the rate of progression and the anatomical sites of symptom onset. Disease-causing mutations in specific genes have been identified and define different subtypes of ALS1. Although several ALS-associated genes have been shown to affect immune functions2, whether specific immune features account for ALS heterogeneity is poorly understood. Amyotrophic lateral sclerosis-4 (ALS4) is characterized by juvenile onset and slow progression3. Patients with ALS4 show motor difficulties by the time that they are in their thirties, and most of them require devices to assist with walking by their fifties. ALS4 is caused by mutations in the senataxin gene (SETX). Here, using Setx knock-in mice that carry the ALS4-causative L389S mutation, we describe an immunological signature that consists of clonally expanded, terminally differentiated effector memory (TEMRA) CD8 T cells in the central nervous system and the blood of knock-in mice. Increased frequencies of antigen-specific CD8 T cells in knock-in mice mirror the progression of motor neuron disease and correlate with anti-glioma immunity. Furthermore, bone marrow transplantation experiments indicate that the immune system has a key role in ALS4 neurodegeneration. In patients with ALS4, clonally expanded TEMRA CD8 T cells circulate in the peripheral blood. Our results provide evidence of an antigen-specific CD8 T cell response in ALS4, which could be used to unravel disease mechanisms and as a potential biomarker of disease state.

Neurodegenerative diseases are challenging for systems biology because of the lack of reliable animal models or patient samples at early disease stages. Induced pluripotent stem cells (iPSCs) could address these challenges. We investigated DNA, RNA, epigenetics, and proteins in iPSC-derived motor neurons from patients with ALS carrying hexanucleotide expansions in C9ORF72. Using integrative computational methods combining all omics datasets, we identified novel and known dysregulated pathways. We used a C9ORF72 Drosophila model to distinguish pathways contributing to disease phenotypes from compensatory ones and confirmed alterations in some pathways in postmortem spinal cord tissue of patients with ALS. A different differentiation protocol was used to derive a separate set of C9ORF72 and control motor neurons. Many individual -omics differed by protocol, but some core dysregulated pathways were consistent. This strategy of analyzing patient-specific neurons provides disease-related outcomes with small numbers of heterogeneous lines and reduces variation from single-omics to elucidate network-based signatures.

Objective: To examine the relationship between body mass index (BMI) and genotype among pre-symptomatic carriers of different pathogenic variants associated with amyotrophic lateral sclerosis. Methods: C9orf72+ carriers, SOD1+ carriers, and pathogenic variant negative controls (Gene-Negatives) were included from 3 largely independent cohorts: ALS Families Project (ALS-Families); Dominantly inherited ALS (DIALS); and Pre-symptomatic Familial ALS (Pre-fALS). First reported (ALS-Families) or measured (DIALS and Pre-fALS) weight and height were used to calculate BMI. Age at weight measurement, self-reported sex (male vs. female), and highest education (high school or below vs. college education vs. graduate school or above) were extracted. The associations between BMI and genotype in each cohort were examined with multivariable linear regression models, adjusted for age, sex, and education. Results: A total of 223 C9orf72+ carriers, 135 SOD1+ carriers, and 191 Gene-Negatives were included, deriving from ALS-Families (n = 114, median age 46, 37% male), DIALS (n = 221, median age 46, 30% male), and Pre-fALS (n = 214, median age 44, 39% male). Adjusting for age, sex, and education, the mean BMI of C9orf72+ carriers was lower than Gene-Negatives by 2.4 units (95% confidence interval [CI] = 0.3–4.6, p = 0.02) in ALS-Families; 2.7 units (95% CI = 0.9–4.4, p = 0.003) in DIALS; and 1.9 units (95% CI = 0.5–4.2, p = 0.12) in Pre-fALS. There were no significant differences in BMI between SOD1+ carriers and Gene-Negatives in any of the 3 cohorts. Conclusions: Compared to Gene-Negatives, average BMI is lower in asymptomatic C9orf72+ carriers across 3 cohorts while no significant difference was found between Gene-Negatives and SOD1+ carriers. [ABSTRACT FROM AUTHOR]

Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) represent two ends of a disease spectrum with shared clinical, genetic and pathological features. These include near ubiquitous pathological inclusions of the RNA-binding protein (RBP) TDP-43, and often the presence of a GGGGCC expansion in the C9ORF72 (C9) gene. Previously, we reported that the sequestration of hnRNP H altered the splicing of target transcripts in C9ALS patients (Conlon et al., 2016). Here, we show that this signature also occurs in half of 50 postmortem sporadic, non-C9 ALS/FTD brains. Furthermore, and equally surprisingly, these 'like-C9' brains also contained correspondingly high amounts of insoluble TDP-43, as well as several other disease-related RBPs, and this correlates with widespread global splicing defects. Finally, we show that the like-C9 sporadic patients, like actual C9ALS patients, were much more likely to have developed FTD. We propose that these unexpected links between C9 and sporadic ALS/FTD define a common mechanism in this disease spectrum.

Introduction/Aims. Primary lateral sclerosis (PLS) is exceedingly rare and has been an enigmatic disease. Recent progress has drastically changed this perception, with early biomarkers being investigated and potential medications for PLS emerging at the preclinical stage. The aim of this paper is to describe a study of PLS natural history and discuss the limitations and proposed solutions to the study of a rare and slowly progressive disease. Methods. The PLS Natural History Study is a 30-site, 24-month, prospective study that is supported by multiple funding sources. The study aims to enroll 50 early PLS (disease duration ≤4 years) and 50 definite PLS (disease duration 4 to 15 years) participants using modified PLS Diagnostic Criteria. Smartphone-based assessments including semi-quantitative and quantitative measures and patient-reported outcomes are utilized. In-person quantitative measures are also completed during site visits. The change in the PLS Functional Rating Scale score is the primary outcome. The study utilizes the NeuroBANK® patient-centric data capture and management platform. The biostatistical analysis plan has been developed. Results. In one year, 28 participants have been recruited. Enrollment has been much slower than anticipated due to the COVID-19 pandemic, the rarity of PLS, and potential study competition for internal resources from ALS clinical trials. Discussion. We discuss the need for more innovative methods to enroll and study individuals with such rare diseases and propose a number of mechanisms by which more efficient enrollment could be facilitated. [ABSTRACT FROM AUTHOR]

The fatal adult motor neuron disease amyotrophic lateral sclerosis (ALS) shares some clinical and pathological overlap with frontotemporal dementia (FTD), an early-onset neurodegenerative disorder. The RNA/DNA binding proteins fused in sarcoma (FUS; also known as TLS) and TAR DNA binding protein-43 (TDP-43) have recently been shown to be genetically and pathologically associated with familial forms of ALS and FTD. It is currently unknown whether perturbation of these proteins results in disease through mechanisms that are independent of normal protein function or via the pathophysiological disruption of molecular processes in which they are both critical. Here, we report that Drosophila mutants in which the homolog of FUS is disrupted exhibit decreased adult viability, diminished locomotor speed, and reduced life span compared with controls. These phenotypes were fully rescued by wild-type human FUS, but not ALS-associated mutant FUS proteins. A mutant of the Drosophila homolog of TDP-43 had similar, but more severe, deficits. Through cross-rescue analysis, we demonstrated that FUS acted together with and downstream of TDP-43 in a common genetic pathway in neurons. Furthermore, we found that these proteins associated with each other in an RNA-dependent complex. Our results establish that FUS and TDP-43 function together in vivo and suggest that molecular pathways requiring the combined activities of both of these proteins may be disrupted in ALS and FTD., Introduction Amyotrophic lateral sclerosis (ALS) is a fatal adult neurodegenerative disorder characterized by progressive motor system dysfunction and loss of cortical and spinal motor neurons. Though predominantly a sporadic disease, [...]

There is still no cure or effective treatment for amyotrophic lateral sclerosis, usually called ALS or Lou Gehrig's disease. However, genetic analysis of hereditary cases has discovered a gene mutation that can cause nerve cells to die.

Abstract Background Gamma motor neurons (γ-MNs) selectively innervate muscle spindle intrafusal fibers and regulate their sensitivity to stretch. They constitute a distinct subpopulation that differs in morphology, physiology and connectivity from α-MNs, which innervate extrafusal muscle fibers and exert force. The mechanisms that control the differentiation of functionally distinct fusimotor neurons are unknown. Progress on this question has been limited by the absence of molecular markers to specifically distinguish and manipulate γ-MNs. Recently, it was reported that early embryonic γ-MN precursors are dependent on GDNF. Using this knowledge we characterized genetic strategies to label developing γ-MNs based on GDNF receptor expression, showed their strict dependence for survival on muscle spindle-derived GDNF and generated an animal model in which γ-MNs are selectively lost. Results In mice heterozygous for both the Hb9::GFP transgene and a tau-lacZ-labeled (TLZ) allele of the GDNF receptor Gfrα1, we demonstrated that small motor neurons with high Gfrα1-TLZ expression and lacking Hb9::GFP display structural and synaptic features of γ-MNs and are selectively lost in mutants lacking target muscle spindles. Loss of muscle spindles also results in the downregulation of Gfrα1 expression in some large diameter MNs, suggesting that spindle-derived factors may also influence populations of α-MNs with β-skeletofusimotor collaterals. These molecular markers can be used to identify γ-MNs from birth to the adult and to distinguish γ- from β-motor axons in the periphery. We also found that postnatal γ-MNs are also distinguished by low expression of the neuronal nuclear protein (NeuN). With these markers of γ-MN identity, we show after conditional elimination of GDNF from muscle spindles that the survival of γ-MNs is selectively dependent on spindle-derived GDNF during the first 2 weeks of postnatal development. Conclusion Neonatal γ-MNs display a unique molecular profile characterized by the differential expression of a series of markers - Gfrα1, Hb9::GFP and NeuN - and the selective dependence on muscle spindle-derived GDNF. Deletion of GDNF expression from muscle spindles results in the selective elimination of γ-MNs with preservation of the spindle and its sensory innervation. This provides a mouse model with which to explore the specific role of γ-fusimotor activity in motor behaviors.

Background: The pathological hallmark in MSA is oligodendrocytic glial cytoplasmic inclusions (GCIs) containing α‐synuclein, in addition to neuronal loss and astrogliosis especially involving the striatonigral and olivopontocerebellar systems. Rarely, TAR DNA‐binding protein of 43 kDa (TDP‐43), a component of ubiquitinated inclusions observed mainly in amyotrophic lateral sclerosis and frontotemporal lobar degeneration has been demonstrated in cases of MSA and, more recently, was shown to colocalize with α‐synuclein pathology in GCIs in 2 patients. Methods: A 66‐year‐old woman presented with a syndrome characterized by spasticity, dysautonomia, bulbar dysfunction, and parkinsonism. Symptoms progressed until her death at age 74. Neuropathological evaluation was performed at the New York Brain Bank at Columbia University. Results: On gross examination, there was striking severe volume loss of the left striatum compared to mild involvement of the right striatum. Microscopically, neuronal loss and gliosis of the putamen and globus pallidus were severe on the left side, in contrast to mild involvement on the right side. Immunohistochemistry for α‐synuclein revealed widespread GCIs. The sections subjected to TDP‐43 antibodies showed a few GCIs with definite nucleocytoplasmic translocation of the labeling within the lenticular nucleus and within the paracentral cortex. Conclusions: This report adds to the evidence that TDP‐43 and α‐synuclein colocalize in GCIs. Whether this coexistence contributes to the pathogenesis of a subset of MSA patients or is an age‐related process is not known. More cases with these peculiar pathological hallmarks might help determine whether TDP‐43 contributes to neurodegeneration in a subset of patients with MSA. [ABSTRACT FROM AUTHOR]

The study of amyotrophic lateral sclerosis (ALS) and potential interventions would be facilitated if motor axon degeneration could be more readily visualized. Here we demonstrate that stimulated Raman scattering (SRS) microscopy could be used to sensitively monitor peripheral nerve degeneration in ALS mouse models and ALS autopsy materials. Three-dimensional imaging of pre-symptomatic SOD1 mouse models and data processing by a correlation-based algorithm revealed that significant degeneration of peripheral nerves could be detected coincidentally with the earliest detectable signs of muscle denervation and preceded physiologically measurable motor function decline. We also found that peripheral degeneration was an early event in FUS as well as C9ORF72 repeat expansion models of ALS, and that serial imaging allowed long-term observation of disease progression and drug effects in living animals. Our study demonstrates that SRS imaging is a sensitive and quantitative means of measuring disease progression, greatly facilitating future studies of disease mechanisms and candidate therapeutics.

Summary: Mutations in the RNA binding protein FUS cause amyotrophic lateral sclerosis (ALS), a fatal adult motor neuron disease. Decreased expression of SMN causes the fatal childhood motor neuron disorder spinal muscular atrophy (SMA). The SMN complex localizes in both the cytoplasm and nuclear Gems, and loss of Gems is a cellular hallmark of fibroblasts in patients with SMA. Here, we report that FUS associates with the SMN complex, mediated by U1 snRNP and by direct interactions between FUS and SMN. Functionally, we show that FUS is required for Gem formation in HeLa cells, and expression of FUS containing a severe ALS-causing mutation (R495X) also results in Gem loss. Strikingly, a reduction in Gems is observed in ALS patient fibroblasts expressing either mutant FUS or TDP-43, another ALS-causing protein that interacts with FUS. The physical and functional interactions among SMN, FUS, TDP-43, and Gems indicate that ALS and SMA share a biochemical pathway, providing strong support for the view that these motor neuron diseases are related. [ABSTRACT FROM AUTHOR]

Motor pools comprise a heterogeneous population of motor neurons that innervate distinct intramuscular targets. While the organization of motor neurons into motor pools has been well described, the time course and mechanism of motor pool diversification into functionally distinct classes remains unclear.&ggr;-Motor neurons (&ggr;-MNs) and &ggr;-motor neurons (&ggr;-MNs) differ in size, molecular identity, synaptic input and peripheral target. While &ggr;-MNs innervate extrafusal skeletal muscle fibers to mediate muscle contraction, &ggr;-MNs innervate intrafusal fibers of the muscle spindle, and regulate sensitivity of the muscle spindle in response to stretch. In this study, we find that the secreted signaling molecule Wnt7a is selectively expressed in &ggr;-MNs in the mouse spinal cord by embryonic day 17.5 and continues to molecularly distinguish &agr;-from &ggr;-MNs into the third postnatal week. Our data demonstrate that Wnt7a is the earliest known &ggr;-MN marker, supporting a model of developmental divergence between &agr;- and &ggr;-MNs at embryonic stages. Furthermore, using Wnt7a expression as an early marker of &ggr;-MN identity, we demonstrate a previously unknown dependence of &ggr;-MNs on a muscle spindlederived, GDNF-independent signal during the first postnatal week. [ABSTRACT FROM AUTHOR]

The mechanisms controlling the formation of synaptic connections between muscle spindle afferents and spinal motor neurons are believed to be regulated by factors originating from muscle spindles. Here, we find that the connections form with appropriate specificity in mice with abnormal spindle development caused by the conditional elimination of the neuregulin1 receptor ErbB2 from muscle precursors. However, despite a modest (~30%) decrease in the number of afferent terminals on motor neuron somata, the amplitude of afferent-evoked synaptic potentials recorded in motor neurons was reduced by ~80%, suggesting that many of the connections that form are functionally silent. The selective elimination of neurotrophin 3 (NT3) from muscle spindles had no effect on the amplitude of afferent-evoked ventral root potentials until the second postnatal week, revealing a late role for spindle-derived NT3 in the functional maintenance of the connections. These findings indicate that spindle-derived factors regulate the strength of the connections but not their initial formation or their specificity. [ABSTRACT FROM AUTHOR]

The maturation of synaptic structures depends on inductive interactions between axons and their prospective targets. One example of such an interaction is the influence of proprioceptive sensory axons on the differentiation of muscle spindles. We have monitored the expression of three transcription factors, Egr3, Pea3, and Erm, that delineate early muscle spindle development in an assay of muscle spindle-inducing signals. We provide genetic evidence that Neuregulin1 (Nrg1) is required for proprioceptive afferent-evoked induction of muscle spindle differentiation in the mouse. Ig-Nrg1 isoforms are preferentially expressed by proprioceptive sensory neurons and are sufficient to induce muscle spindle differentiation in vivo, whereas CRD-Nrg1 isoforms are broadly expressed in sensory and motor neurons but are not required for muscle spindle induction. [Copyright &y& Elsevier]

Recent progress in therapeutics for amyotrophic lateral sclerosis (ALS) has spurred development and imbued the field of ALS with hope for more breakthroughs, yet substantial scientific gaps persist. This unmet need remains a stark reminder that innovative paradigms are needed to invigorate ALS research. To move toward more informative, targeted, and personalized drug development, the National Institutes of Health (NIH) established a national ALS clinical research consortium called Access for ALL in ALS (ALL ALS). This new consortium is a multi‐institutional effort that aims to organize the ALS clinical research landscape in the United States. ALL ALS is operating in partnership with several stakeholders to operationalize the recommendations of the Accelerating Access to Critical Therapies for ALS Act (ACT for ALS) Public Private Partnership. ALL ALS will provide a large‐scale, centralized, and readily accessible infrastructure for the collection and storage of a wide range of data from people living with ALS (symptomatic cohort) or who may be at risk of developing ALS (asymptomatic ALS gene carriers). Importantly, ALL ALS is designed to encourage community engagement, equity, and inclusion. The consortium is prioritizing the enrollment of geographically, ethnoculturally, and socioeconomically diverse participants. Collected data include longitudinal clinical data and biofluids, genomic, and digital biomarkers that will be harmonized and linked to the central Accelerating Medicines Partnership for ALS (AMP ALS) portal for sharing with the research community. The aim of ALL ALS is to deliver a comprehensive, inclusive, open‐science dataset to help researchers answer important scientific questions of clinical relevance in ALS. [ABSTRACT FROM AUTHOR]

Summary Rare mutations in TARDBP , the gene encoding TDP-43, cause amyotrophic lateral sclerosis (ALS), and TDP-43 pathology is seen in a large majority of ALS patients, suggesting a central pathogenic role of this regulatory protein. The consequences of TARDBP mutations on TDP-43 function and the mechanism by which mutant TDP-43 causes neurodegeneration remain uncertain. Here, we characterize a series of knockin mice carrying disease-associated TARDBP mutations. We demonstrate that TDP-43M337V and TDP-43G298S are functional, each rescuing the lethality of TDP-43 loss of function. In a subset of aged heterozygous knockin mice, we observe the earliest signs of selective motor neuron degeneration, demonstrating that physiological levels of mutant TDP-43 are sufficient to initiate disease. Furthermore, aged homozygous mutants develop selective, asymmetric motor neuron pathology, providing in vivo evidence of TDP-43 dose-dependent neurotoxicity. These knockin mice represent a faithful in vivo model of early-stage ALS and enable future exploration of TDP-43-associated neurodegeneration. Graphical Abstract Highlights • In TARDBP knockin mice, TDP-43M337V and TDP-43G298S mutant alleles are functional • Mutant TDP-43 causes dose-dependent, selective, asymmetrical motor axon withdrawal • Microgliosis and astrocytosis in spinal cord segments precede muscle denervation • Mutant TDP-43 is associated with focal onset of disease and incomplete penetrance In a series of knockin mice carrying ALS-associated TARDBP mutations, Ebstein et al. demonstrate that the mutant alleles TDP-43M337V and TDP-43G298S are functional but in a dose-dependent manner cause early, selective motor neuron degeneration in a subpopulation of aged mice. This represents a faithful in vivo model of early-stage ALS. [ABSTRACT FROM AUTHOR]

The RNA-binding protein FUS participates in several RNA biosynthetic processes and has been linked to the pathogenesis of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia. Here we report that FUS controls back-splicing reactions leading to circular RNA (circRNA) production. We identified circRNAs expressed in in vitro-derived mouse motor neurons (MNs) and determined that the production of a considerable number of these circRNAs is regulated by FUS. Using RNAi and overexpression of wild-type and ALS-associated FUS mutants, we directly correlate the modulation of circRNA biogenesis with alteration of FUS nuclear levels and with putative toxic gain of function activities. We also demonstrate that FUS regulates circRNA biogenesis by binding the introns flanking the back-splicing junctions and that this control can be reproduced with artificial constructs. Most circRNAs are conserved in humans and specific ones are deregulated in human-induced pluripotent stem cell-derived MNs carrying the FUSP525L mutation associated with ALS. [ABSTRACT FROM AUTHOR]

In the neurodegenerative disorders amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), expansion of the G 4 C 2 hexanucleotide repeat in the gene C9orf72 is a most common known cause of the disease. Here we use atomic force microscopy (AFM) and gel electrophoresis to visualize the formation of higher-order structures by RNA G 4 C 2 repeats in physiologically relevant conditions. For the RNA sequence r[G 4 C 2 G 4 ], we observed G-wires with left-handed undulating features of 4.4-nm periodicity and a uniform height which is consistently higher than that of a duplex B-DNA. These higher-order structures were not degraded fully when treated with a mixture of RNase A and RNase T1. Similarly, higher-order structures were observed for sequences containing three or four G 4 C 2 repeats, pointing towards their potential formation in longer sequence contexts. Our observations suggest that RNA G-quadruplex blocks and G-wires can accumulate in cells containing G 4 C 2 repeat transcripts. • Expansion of the G 4 C 2 hexanucleotide repeat in the gene C9orf72 is the most common cause of ALS and FTD. • We observed RNA G-wires formed by G 4 C 2 repeats with left-handed undulating features of 4.4-nm periodicity. • RNA G-wires are stable in the presence of RNases, suggesting that they can accumulate in cells containing G 4 C 2 repeats. [ABSTRACT FROM AUTHOR]

• New set of human HB9 and VACHT targeted iPSC reporter lines for purification of motor neurons and other cholinergic neurons. • The Cre-lox amplification of reporter expression is compatible with live-imaging and long-term culture studies. • Cre based reporters expressing CD14 receptor are useful for motor neuron purification at scale. Reliable and consistent pluripotent stem cell reporter systems for efficient purification and visualization of motor neurons are essential reagents for the study of normal motor neuron biology and for effective disease modeling. To overcome the inherent noisiness of transgene-based reporters, we developed a new series of human induced pluripotent stem cell lines by knocking in tdTomato, Cre, or CreERT2 recombinase into the HB9 (MNX1) or VACHT (SLC18A3) genomic loci. The new lines were validated by directed differentiation into spinal motor neurons and immunostaining for motor neuron markers HB9 and ISL1. To facilitate efficient purification of spinal motor neurons, we further engineered the VACHT-Cre cell line with a validated, conditional CD14-GFP construct that allows for both fluorescence-based identification of motor neurons, as well as magnetic-activated cell sorting (MACS) to isolate differentiated motor neurons at scale. The targeting strategies developed here offer a standardized platform for reproducible comparison of motor neurons across independently derived pluripotent cell lines. [ABSTRACT FROM AUTHOR]

Amyotrophic lateral sclerosis (ALS), commonly known as Lou Gehrig’s disease, is a devastating neurodegenerative disorder lacking effective treatments. ALS pathology is linked to mutations in .20 different genes indicating a complex underlying genetic architecture that is effectively unknown. Here, in an attempt to identify genes and pathways for potential therapeutic intervention and explore the genetic circuitry underlying Drosophila models of ALS, we carry out two independent genome-wide screens for modifiers of degenerative phenotypes associated with the expression of transgenic constructs carrying familial ALS-causing alleles of FUS (hFUSR521C) and TDP-43 (hTDP-43M337V). We uncover a complex array of genes affecting either or both of the two strains, and investigate their activities in additional ALS models. Our studies indicate the pathway that governs phospholipase D activity as a major modifier of ALS-related phenotypes, a notion supported by data we generated in mice and others collected in humans. [ABSTRACT FROM AUTHOR]

Abstract: For studies of motor neuron function or for therapeutic purposes, novel pseudotype HIV-1-based vectors were developed that are capable of expressing transgenes in motor neurons following injection into mouse hind limb muscles. To specifically target motor neurons, glycoproteins from two rabies virus (RV) isolates, the mouse-brain adapted challenge virus 24 (CVS-24) variants, CVS-N2c and CVS-B2c were evaluated for pseudotype formation with an HIV-1-based vector. Both RV glycoproteins incorporated into vector envelopes, and both pseudotypes yielded high titers with Hek293T and cortical plate neuron cultures. Increased neuronotropism by the CVS-N2c pseudotype was not observed, suggesting that vector tropism is not solely determined by the fusogenic viral glycoprotein. Vector injection into hind limb muscles resulted in EYFP reporter gene expression in the injected muscle fibers and in spinal cord motor neurons innervating the same muscle, indicating retrograde vector transport. Intramuscular vector injections into the soleus and tibialis anterior muscles transduced 26% and 16% of all motor neurons in each motor nucleus, respectively. These transduction efficiencies may allow novel approaches to functional studies of the motor system and the treatment of neuromuscular disease. [Copyright &y& Elsevier]

CHCHD10 is mutated in rare cases of FTD and ALS and aggregates in mouse models of disease. Here we show that the disordered N-terminal domain of CHCHD10 forms amyloid fibrils and report their cryoEM structure. Disease-associated mutations cannot be accommodated by the WT fibril structure, while sequence differences between CHCHD10 and CHCHD2 are tolerated, explaining the co-aggregation of the two proteins and linking CHCHD10 and CHCHD2 amyloid fibrils to neurodegeneration., Competing Interests: Competing Interests: The authors declare no competing interests.