20 results on '"Sela D"'
Search Results
2. Effects of Red Blood Cell Transfusion on Patients Undergoing Cardiac Surgery in Queensland—A Retrospective Cohort Study
- Author
-
Dhanapathy, V., Obonyo, N., White, N., Sela, D., Rachakonda, R., Tunbridge, M., Sim, B., Teo, D., Hoe, L. See, Fanning, J., Tung, J., Suen, J., and Fraser, J.
- Published
- 2023
- Full Text
- View/download PDF
3. Phage & phosphatase: a novel phage-based probe for rapid, multi-platform detection of bacteria.
- Author
-
Alcaine, S. D., Pacitto, D., Sela, D. A., and Nugen, S. R.
- Subjects
BACTERIOPHAGES ,PHOSPHATASES ,PATHOGENIC microorganisms ,DRUG resistance in bacteria ,DRUG resistance in microorganisms - Abstract
Genetic engineering of bacteriophages allows for the development of rapid, highly specific, and easily manufactured probes for the detection of bacterial pathogens. A challenge for novel probes is the ease of their adoption in real world laboratories. We have engineered the bacteriophage T7, which targets Escherichia coli, to carry the alkaline phosphatase gene, phoA. This inclusion results in phoA overexpression following phage infection of E. coli. Alkaline phosphatase is commonly used in a wide range of diagnostics, and thus a signal produced by our phage-based probe could be detected using common laboratory equipment. Our work demonstrates the successful: (i) modification of T7 phage to carry phoA; (ii) overexpression of alkaline phosphatase in E. coli; and (iii) detection of this T7-induced alkaline phosphatase activity using commercially available colorimetric and chemilumiscent methods. Furthermore, we demonstrate the application of our phage-based probe to rapidly detect low levels of bacteria and discern the antibiotic resistance of E. coli isolates. Using our bioengineered phage-based probe we were able to detect 10
3 CFU per mL of E. coli in 6 hours using a chemiluminescent substrate and 104 CFU per mL within 7.5 hours using a colorimetric substrate. We also show the application of this phage-based probe for antibiotic resistance testing. We were able to determine whether an E. coli isolate was resistant to ampicillin within 4.5 hours using chemiluminescent substrate and within 6 hours using a colorimetric substrate. This phage-based scheme could be readily adopted in labs without significant capital investments and can be translated to other phage–bacteria pairs for further detection. [ABSTRACT FROM AUTHOR]- Published
- 2015
- Full Text
- View/download PDF
4. Assessment and diagnosis of right ventricular failure-retrospection and future directions.
- Author
-
Ro SK, Sato K, Ijuin S, Sela D, Fior G, Heinsar S, Kim JY, Chan J, Nonaka H, Lin ACW, Bassi GL, Platts DG, Obonyo NG, Suen JY, and Fraser JF
- Abstract
The right ventricle (RV) has a critical role in hemodynamics and right ventricular failure (RVF) often leads to poor clinical outcome. Despite the clinical importance of RVF, its definition and recognition currently rely on patients' symptoms and signs, rather than on objective parameters from quantifying RV dimensions and function. A key challenge is the geometrical complexity of the RV, which often makes it difficult to assess RV function accurately. There are several assessment modalities currently utilized in the clinical settings. Each diagnostic investigation has both advantages and limitations according to its characteristics. The purpose of this review is to reflect on the current diagnostic tools, consider the potential technological advancements and propose how to improve the assessment of right ventricular failure. Advanced technique such as automatic evaluation with artificial intelligence and 3-dimensional assessment for the complex RV structure has a potential to improve RV assessment by increasing accuracy and reproducibility of the measurements. Further, noninvasive assessments for RV-pulmonary artery coupling and right and left ventricular interaction are also warranted to overcome the load-related limitations for the accurate evaluation of RV contractile function. Future studies to cross-validate the advanced technologies in various populations are required., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (© 2023 Ro, Sato, Ijuin, Sela, Fior, Heinsar, Kim, Chan, Nonaka, Lin, Bassi, Platts, Obonyo, Suen and Fraser.)
- Published
- 2023
- Full Text
- View/download PDF
5. Hemorrhage, Disseminated Intravascular Coagulopathy, and Thrombosis Complications Among Critically Ill Patients with COVID-19: An International COVID-19 Critical Care Consortium Study.
- Author
-
Fanning JP, Weaver N, Fanning RB, Griffee MJ, Cho SM, Panigada M, Obonyo NG, Zaaqoq AM, Rando H, Chia YW, Fan BE, Sela D, Chiumello D, Coppola S, Labib A, Whitman GJR, Arora RC, Kim BS, Motos A, Torres A, Barbé F, Grasselli G, Zanella A, Etchill E, Usman AA, Feth M, White NM, Suen JY, Li Bassi G, Peek GJ, Fraser JF, and Dalton H
- Subjects
- Adult, Humans, Prospective Studies, Critical Illness, Critical Care, Hemorrhage epidemiology, Hemorrhage etiology, Retrospective Studies, COVID-19 complications, COVID-19 epidemiology, COVID-19 therapy, Thrombosis epidemiology, Thrombosis etiology
- Abstract
Objectives: To determine the prevalence and outcomes associated with hemorrhage, disseminated intravascular coagulopathy, and thrombosis (HECTOR) complications in ICU patients with COVID-19., Design: Prospective, observational study., Setting: Two hundred twenty-nine ICUs across 32 countries., Patients: Adult patients (≥ 16 yr) admitted to participating ICUs for severe COVID-19 from January 1, 2020, to December 31, 2021., Interventions: None., Measurements and Main Results: HECTOR complications occurred in 1,732 of 11,969 study eligible patients (14%). Acute thrombosis occurred in 1,249 patients (10%), including 712 (57%) with pulmonary embolism, 413 (33%) with myocardial ischemia, 93 (7.4%) with deep vein thrombosis, and 49 (3.9%) with ischemic strokes. Hemorrhagic complications were reported in 579 patients (4.8%), including 276 (48%) with gastrointestinal hemorrhage, 83 (14%) with hemorrhagic stroke, 77 (13%) with pulmonary hemorrhage, and 68 (12%) with hemorrhage associated with extracorporeal membrane oxygenation (ECMO) cannula site. Disseminated intravascular coagulation occurred in 11 patients (0.09%). Univariate analysis showed that diabetes, cardiac and kidney diseases, and ECMO use were risk factors for HECTOR. Among survivors, ICU stay was longer (median days 19 vs 12; p < 0.001) for patients with versus without HECTOR, but the hazard of ICU mortality was similar (hazard ratio [HR] 1.01; 95% CI 0.92-1.12; p = 0.784) overall, although this hazard was identified when non-ECMO patients were considered (HR 1.13; 95% CI 1.02-1.25; p = 0.015). Hemorrhagic complications were associated with an increased hazard of ICU mortality compared to patients without HECTOR complications (HR 1.26; 95% CI 1.09-1.45; p = 0.002), whereas thrombosis complications were associated with reduced hazard (HR 0.88; 95% CI 0.79-0.99, p = 0.03)., Conclusions: HECTOR events are frequent complications of severe COVID-19 in ICU patients. Patients receiving ECMO are at particular risk of hemorrhagic complications. Hemorrhagic, but not thrombotic complications, are associated with increased ICU mortality., Competing Interests: Dr. J. P. Fanning received funding from the Australian-American Fulbright Commission and Metro North Clinical Research Fellowship, Queensland Government, Australia. Drs. Suen, Li Bassi, and Fraser received support for article research from the Bill and Melinda Gates Foundation. Dr. Cho is funded by National Heart, Lung, and Blood Institute 1K23HL157610. Dr. Rando received funding from the American Heart Association. Dr. Whitman disclosed that he is 50% owner of a patent for a medical device for GWBN, LLC and that he received funding from Cellphire/Avania as principal investigator for a national study. Dr. Arora received funding from Edwards LifeSciences and Avir Pharma. Dr. Grasselli received funding from Getinge, Fisher & Paykel, Draeger Medical, Merck Sharp and Dohme, Cook Medical, and GlaxoSmithKline. Dr. Usman received support for article research from the National Institutes of Health. Drs. Suen’s and Li Bassi’s institutions received funding from The Bill and Melinda Gates Foundation. Dr. Suen is funded by the Advance Queensland fellowship program, Queensland Government, Australia. Dr. Li Bassi’s institution received funding from Fisher & Paykel. Dr. Li Bassi is a recipient of the Biomedical international training research programme for excellent clinician-scientists (BITRECS) fellowship; the “BITRECS” project has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement no. 754550 and from the “La Caixa” Foundation (ID 100010434), under the agreement LCF/PR/GN18/50310006. Dr. Dalton received funding from extracorporeal membrane oxygenation concepts, entegrion, and hemocue. The remaining authors have disclosed that they do not have any potential conflicts of interest., (Copyright © 2023 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the Society of Critical Care Medicine and Wolters Kluwer Health, Inc.)
- Published
- 2023
- Full Text
- View/download PDF
6. Human Milk Antibodies Against S1 and S2 Subunits from SARS-CoV-2, HCoV-OC43, and HCoV-229E in Mothers with A Confirmed COVID-19 PCR, Viral SYMPTOMS, and Unexposed Mothers.
- Author
-
Demers-Mathieu V, DaPra C, Mathijssen G, A Sela D, M Jarvinen K, Seppo A, Fels S, and Medo E
- Subjects
- Adult, Antigen-Antibody Reactions, COVID-19 virology, Cross Reactions, Female, Humans, Immunoglobulin G immunology, Immunoglobulin G metabolism, Immunoglobulin M immunology, Mothers, Polymerase Chain Reaction, RNA, Viral metabolism, SARS-CoV-2 genetics, SARS-CoV-2 isolation & purification, SARS-CoV-2 metabolism, Antibodies, Viral immunology, COVID-19 pathology, Coronavirus 229E, Human metabolism, Coronavirus OC43, Human metabolism, Milk, Human metabolism, Spike Glycoprotein, Coronavirus immunology
- Abstract
Background: Preexisting immunity to SARS-CoV-2 could be related to cross-reactive antibodies to common human-coronaviruses (HCoVs). This study aimed to evaluate whether human milk antibodies against to S1 and S2 subunits SARS-CoV-2 are cross-reactive to S1 and S2 subunits HCoV-OC43 and HCoV-229E in mothers with a confirmed COVID-19 PCR test, in mothers with previous viral symptoms during COVID-19 pandemic, and in unexposed mothers; Methods: The levels of secretory IgA (SIgA)/IgA, secretory IgM (SIgM)/IgM, and IgG specific to S1 and S2 SARS-CoV-2, and reactive to S1 + S2 HCoV-OC43, and HCoV-229E were measured in milk from 7 mothers with a confirmed COVID-19 PCR test, 20 mothers with viral symptoms, and unexposed mothers (6 Ctl1-2018 and 16 Ctl2-2018) using ELISA; Results: The S2 SARS-CoV-2 IgG levels were higher in the COVID-19 PCR ( p = 0.014) and viral symptom ( p = 0.040) groups than in the Ctl1-2018 group. We detected a higher number of positive correlations between the antigens and secretory antibodies in the COVID-19 PCR group than in the viral symptom and Ctl-2018 groups. S1 + S2 HCoV-OC43-reactive IgG was higher in the COVID-19 group than in the control group ( p = 0.002) but did not differ for the other antibodies; Conclusions: Mothers with a confirmed COVID-19 PCR and mothers with previous viral symptoms had preexisting human milk antibodies against S2 subunit SARS-CoV-2. Human milk IgG were more specific to S2 subunit SARS-CoV-2 than other antibodies, whereas SIgA and SIgM were polyreactive and cross-reactive to S1 or S2 subunit SARS-CoV-2.
- Published
- 2021
- Full Text
- View/download PDF
7. Measuring nucleus mechanics within a living multicellular organism: Physical decoupling and attenuated recovery rate are physiological protective mechanisms of the cell nucleus under high mechanical load.
- Author
-
Zuela-Sopilniak N, Bar-Sela D, Charar C, Wintner O, Gruenbaum Y, and Buxboim A
- Subjects
- Animals, Biomechanical Phenomena, Caenorhabditis elegans, Chromatin metabolism, Cytoskeleton metabolism, Extracellular Matrix metabolism, Microtubules metabolism, Models, Biological, Nuclear Envelope metabolism, Nuclear Matrix metabolism, Stress, Mechanical, Cell Nucleus metabolism, Molecular Imaging methods, Rheology methods
- Abstract
Nuclei within cells are constantly subjected to compressive, tensile, and shear forces, which regulate nucleoskeletal and cytoskeletal remodeling, activate signaling pathways, and direct cell-fate decisions. Multiple rheological methods have been adapted for characterizing the response to applied forces of isolated nuclei and nuclei within intact cells. However, in vitro measurements fail to capture the viscoelastic modulation of nuclear stress-strain relationships by the physiological tethering to the surrounding cytoskeleton, extracellular matrix and cells, and tissue-level architectures. Using an equiaxial stretching apparatus, we applied a step stress and measured nucleus deformation dynamics within living Caenorhabditis elegans nematodes. Nuclei deformed nonmonotonically under constant load. Nonmonotonic deformation was conserved across tissues and robust to nucleoskeletal and cytoskeletal perturbations, but it required intact linker of nucleoskeleton and cytoskeleton complex attachments. The transition from creep to strain recovery fits a tensile-compressive linear viscoelastic model that is indicative of nucleoskeletal-cytoskeletal decoupling under high load. Ce-lamin ( lmn-1 ) knockdown softened the nucleus, whereas nematode aging stiffened the nucleus and decreased deformation recovery rate. Recovery lasted minutes rather than seconds due to physiological damping of the released mechanical energy, thus protecting nuclear integrity and preventing chromatin damage.
- Published
- 2020
- Full Text
- View/download PDF
8. Bioengineering bacteriophages to enhance the sensitivity of phage amplification-based paper fluidic detection of bacteria.
- Author
-
Alcaine SD, Law K, Ho S, Kinchla AJ, Sela DA, and Nugen SR
- Subjects
- Alkaline Phosphatase genetics, Bacterial Proteins genetics, Escherichia coli genetics, Genetic Engineering methods, Limit of Detection, Maltose-Binding Proteins genetics, Up-Regulation, Bacteriophage T7 genetics, Bioengineering methods, Biosensing Techniques methods, Environmental Monitoring methods, Escherichia coli isolation & purification, Escherichia coli virology, Rivers microbiology
- Abstract
Bacteriophage (phage) amplification is an attractive method for the detection of bacteria due to a narrow phage-host specificity, short amplification times, and the phages' ability to differentiate between viable and non-viable bacterial cells. The next step in phage-based bacteria detection is leveraging bioengineered phages to create low-cost, rapid, and easy-to-use detection platforms such as lateral flow assays. Our work establishes the proof-of-concept for the use of bioengineered T7 phage strains to increase the sensitivity of phage amplification-based lateral flow assays. We have demonstrated a greater than 10-fold increase in sensitivity using a phage-based protein reporter, maltose-binding protein, over the detection of replicated T7 phage viron itself, and a greater then 100-fold increase in sensitivity using a phage-based enzymatic reporter, alkaline phosphatase. This increase in sensitivity enabled us to detect 10(3)CFU/mL of Escherichia coli in broth after 7h, and by adding a filter concentration step, the ability to detect a regulatory relevant E. coli concentration of 100CFU/100mL in inoculated river water after 9h, where the current standard requires days for results. The combination of the paper fluidic format with phage-based detection provides a platform for the development of novel diagnostics that are sensitive, rapid, and easy to use., (Copyright © 2016 Elsevier B.V. All rights reserved.)
- Published
- 2016
- Full Text
- View/download PDF
9. Carbon assimilation and accumulation of cyanophycin during the development of dormant cells (akinetes) in the cyanobacterium Aphanizomenon ovalisporum.
- Author
-
Sukenik A, Maldener I, Delhaye T, Viner-Mozzini Y, Sela D, and Bormans M
- Abstract
Akinetes are spore-like non-motile cells that differentiate from vegetative cells of filamentous cyanobacteria from the order Nostocales. They play a key role in the survival and distribution of these species and contribute to their perennial blooms. Here, we demonstrate variations in cellular ultrastructure during akinete formation concomitant with accumulation of cyanophycin; a copolymer of aspartate and arginine that forms storage granules. Cyanophycin accumulation is initiated in vegetative cells few days post-exposure to akinete inducing conditions. This early accumulated cyanophycin pool in vegetative cells disappears as a nearby cell differentiates to an akinete and stores large pool of cyanophycin. During the akinete maturation, the cyanophycin pool is further increased and comprise up to 2% of the akinete volume. The cellular pattern of photosynthetic activity during akinete formation was studied by a nano-metric scale secondary ion mass spectrometry (NanoSIMS) analysis in (13)C-enriched cultures. Quantitative estimation of carbon assimilation in vegetative cells and akinetes (filament-attached and -free) indicates that vegetative cells maintain their basal activity while differentiating akinetes gradually reduce their activity. Mature-free akinetes practically lost their photosynthetic activity although small fraction of free akinetes were still photosynthetically active. Additional (13)C pulse-chase experiments indicated rapid carbon turnover during akinete formation and de novo synthesis of cyanophycin in vegetative cells 4 days post-induction of akinete differentiation.
- Published
- 2015
- Full Text
- View/download PDF
10. Role for human mediator subunit MED25 in recruitment of mediator to promoters by endoplasmic reticulum stress-responsive transcription factor ATF6α.
- Author
-
Sela D, Conkright JJ, Chen L, Gilmore J, Washburn MP, Florens L, Conaway RC, and Conaway JW
- Subjects
- Activating Transcription Factor 6 genetics, Cell Line, Histone Acetyltransferases genetics, Histone Acetyltransferases metabolism, Humans, Mediator Complex genetics, Multienzyme Complexes genetics, Multienzyme Complexes metabolism, Protein Structure, Tertiary, Activating Transcription Factor 6 metabolism, Endoplasmic Reticulum Stress physiology, Mediator Complex metabolism, Promoter Regions, Genetic physiology
- Abstract
Transcription factor ATF6α functions as a master regulator of endoplasmic reticulum (ER) stress response genes. In response to ER stress, ATF6α translocates from its site of latency in the ER membrane to the nucleus, where it activates RNA polymerase II transcription of ER stress response genes upon binding sequence-specifically to ER stress response enhancer elements (ERSEs) in their promoter-regulatory regions. In a recent study, we demonstrated that ATF6α activates transcription of ER stress response genes by a mechanism involving recruitment to ERSEs of the multisubunit Mediator and several histone acetyltransferase (HAT) complexes, including Spt-Ada-Gcn5 (SAGA) and Ada-Two-A-containing (ATAC) (Sela, D., Chen, L., Martin-Brown, S., Washburn, M.P., Florens, L., Conaway, J.W., and Conaway, R.C. (2012) J. Biol. Chem. 287, 23035-23045). In this study, we extend our investigation of the mechanism by which ATF6α supports recruitment of Mediator to ER stress response genes. We present findings arguing that Mediator subunit MED25 plays a critical role in this process and identify a MED25 domain that serves as a docking site on Mediator for the ATF6α transcription activation domain.
- Published
- 2013
- Full Text
- View/download PDF
11. Overexpression of AtSHN1/WIN1 provokes unique defense responses.
- Author
-
Sela D, Buxdorf K, Shi JX, Feldmesser E, Schreiber L, Aharoni A, and Levy M
- Subjects
- Arabidopsis genetics, Arabidopsis microbiology, Bacteria, Cell Death genetics, Fungi, Hydrogen Peroxide metabolism, Mutation, Oxidation-Reduction, Oxidative Stress genetics, Phenotype, Plant Diseases microbiology, Plant Leaves genetics, Plant Leaves microbiology, Reactive Oxygen Species metabolism, Arabidopsis physiology, Arabidopsis Proteins genetics, Disease Resistance genetics, Gene Expression, Plant Diseases genetics, Trans-Activators genetics, Transcription Factors genetics
- Abstract
The plant cell cuticle serves as the first barrier protecting plants from mechanical injury and invading pathogens. The cuticle can be breached by cutinase-producing pathogens and the degradation products may activate pathogenesis signals in the invading pathogens. Cuticle degradation products may also trigger the plant's defense responses. Botrytis cinerea is an important plant pathogen, capable of attacking and causing disease in a wide range of plant species. Arabidopsis thaliana shn1-1D is a gain-of-function mutant, which has a modified cuticular lipid composition. We used this mutant to examine the effect of altering the whole-cuticle metabolic pathway on plant responses to B. cinerea attack. Following infection with B. cinerea, the shn1-1D mutant discolored more quickly, accumulated more H2O2, and showed accelerated cell death relative to wild-type (WT) plants. Whole transcriptome analysis of B. cinerea-inoculated shn1-1D vs. WT plants revealed marked upregulation of genes associated with senescence, oxidative stress and defense responses on the one hand, and genes involved in the magnitude of defense-response control on the other. We propose that altered cutin monomer content and composition of shn1-1D plants triggers excessive reactive oxygen species accumulation and release which leads to a strong, unique and uncontrollable defense response, resulting in plant sensitivity and death.
- Published
- 2013
- Full Text
- View/download PDF
12. Endoplasmic reticulum stress-responsive transcription factor ATF6α directs recruitment of the Mediator of RNA polymerase II transcription and multiple histone acetyltransferase complexes.
- Author
-
Sela D, Chen L, Martin-Brown S, Washburn MP, Florens L, Conaway JW, and Conaway RC
- Subjects
- Activating Transcription Factor 6 chemistry, Activating Transcription Factor 6 metabolism, Chromatin physiology, DNA-Binding Proteins chemistry, DNA-Binding Proteins genetics, DNA-Binding Proteins metabolism, Endoplasmic Reticulum Chaperone BiP, Endoplasmic Reticulum Stress genetics, Heat-Shock Proteins chemistry, Heat-Shock Proteins genetics, Histone Acetyltransferases chemistry, Histone Acetyltransferases genetics, Humans, Mass Spectrometry methods, Mediator Complex metabolism, Protein Structure, Tertiary, RNA Polymerase II metabolism, Signal Transduction genetics, Transcription, Genetic physiology, Activating Transcription Factor 6 genetics, Endoplasmic Reticulum Stress physiology, Histone Acetyltransferases metabolism, Mediator Complex genetics, RNA Polymerase II genetics
- Abstract
The basic leucine zipper transcription factor ATF6α functions as a master regulator of endoplasmic reticulum (ER) stress response genes. Previous studies have established that, in response to ER stress, ATF6α translocates to the nucleus and activates transcription of ER stress response genes upon binding sequence specifically to ER stress response enhancer elements in their promoters. In this study, we investigate the biochemical mechanism by which ATF6α activates transcription. By exploiting a combination of biochemical and multidimensional protein identification technology-based mass spectrometry approaches, we have obtained evidence that ATF6α functions at least in part by recruiting to the ER stress response enhancer elements of ER stress response genes a collection of RNA polymerase II coregulatory complexes, including the Mediator and multiple histone acetyltransferase complexes, among which are the Spt-Ada-Gcn5 acetyltransferase (SAGA) and Ada-Two-A-containing (ATAC) complexes. Our findings shed new light on the mechanism of action of ATF6α, and they outline a straightforward strategy for applying multidimensional protein identification technology mass spectrometry to determine which RNA polymerase II transcription factors and coregulators are recruited to promoters and other regulatory elements to control transcription.
- Published
- 2012
- Full Text
- View/download PDF
13. Protein-Linked Glycan Degradation in Infants Fed Human Milk.
- Author
-
Dallas DC, Sela D, Underwood MA, German JB, and Lebrilla C
- Abstract
Many human milk proteins are glycosylated. Glycosylation is important in protecting bioactive proteins and peptide fragments from digestion. Protein-linked glycans have a variety of functions; however, there is a paucity of information on protein-linked glycan degradation in either the infant or the adult digestive system. Human digestive enzymes can break down dietary disaccharides and starches, but most of the digestive enzymes required for complex protein-linked glycan degradation are absent from both human digestive secretions and the external brush border membrane of the intestinal lining. Indeed, complex carbohydrates remain intact throughout their transit through the stomach and small intestine, and are undegraded by in vitro incubation with either adult pancreatic secretions or intact intestinal brush border membranes. Human gastrointestinal bacteria, however, produce a wide variety of glycosidases with regio- and anomeric specificities matching those of protein-linked glycan structures. These bacteria degrade a wide array of complex carbohydrates including various protein-linked glycans. That bacteria possess glycan degradation capabilities, whereas the human digestive system, perse, does not, suggests that most dietary protein-linked glycan breakdown will be of bacterial origin. In addition to providing a food source for specific bacteria in the colon, protein-linked glycans from human milk may act as decoys for pathogenic bacteria to prevent invasion and infection of the host. The composition of the intestinal microbiome may be particularly important in the most vulnerable humans-the elderly, the immunocompromised, and infants (particularly premature infants).
- Published
- 2012
- Full Text
- View/download PDF
14. The tumour antigen PRAME is a subunit of a Cul2 ubiquitin ligase and associates with active NFY promoters.
- Author
-
Costessi A, Mahrour N, Tijchon E, Stunnenberg R, Stoel MA, Jansen PW, Sela D, Martin-Brown S, Washburn MP, Florens L, Conaway JW, Conaway RC, and Stunnenberg HG
- Subjects
- Chromatin Immunoprecipitation, Humans, Protein Binding, Protein Subunits metabolism, Antigens, Neoplasm metabolism, CCAAT-Binding Factor metabolism, Cullin Proteins metabolism, Promoter Regions, Genetic, Ubiquitin-Protein Ligases metabolism
- Abstract
The human tumour antigen PRAME (preferentially expressed antigen of melanoma) is frequently overexpressed in tumours. High PRAME levels correlate with poor clinical outcome of several cancers, but the mechanisms by which PRAME could be involved in tumourigenesis remain largely elusive. We applied protein-complex purification strategies and identified PRAME as a substrate recognition subunit of a Cullin2-based E3 ubiquitin ligase. PRAME can be recruited to DNA in vitro, and genome-wide chromatin immunoprecipitation experiments revealed that PRAME is specifically enriched at transcriptionally active promoters that are also bound by NFY and at enhancers. Our results are consistent with a role for the PRAME ubiquitin ligase complex in NFY-mediated transcriptional regulation.
- Published
- 2011
- Full Text
- View/download PDF
15. Regulation of UMSBP activities through redox-sensitive protein domains.
- Author
-
Sela D and Shlomai J
- Subjects
- Amino Acid Sequence, Animals, Crithidia fasciculata genetics, Crithidia fasciculata metabolism, Cysteine chemistry, DNA, Kinetoplast chemistry, DNA-Binding Proteins metabolism, Methionine chemistry, Molecular Sequence Data, Nucleoproteins metabolism, Oxidation-Reduction, Protein Structure, Tertiary, Protozoan Proteins metabolism, Sequence Homology, Amino Acid, Zinc Fingers, DNA, Kinetoplast metabolism, DNA-Binding Proteins chemistry, Protozoan Proteins chemistry, Replication Origin
- Abstract
UMSBP is a CCHC-type zinc finger protein, which functions during replication initiation of kinetoplast DNA minicircles and the segregation of kinetoplast DNA networks. Interactions of UMSBP with origin sequences, as well as the protein oligomerization, are affected by its redox state. Reduction yields UMSBP monomers and activates its binding to DNA, while oxidation drives UMSBP oligomerization and impairs its DNA-binding activity. Kinetics analyses of UMSBP-DNA interactions revealed that redox affects the association of free UMSBP with the DNA, but has little effect on its dissociation from the nucleoprotein complex. A previously proposed model, suggesting that binding of DNA is regulated via the reversible interconversions of active UMSBP monomers and inactive oligomers, was challenged here, revealing that the two redox-driven processes are not interrelated. No correlation could be observed between DNA-binding inhibition and UMSBP oligomerization, upon oxidation of UMSBP. Moreover, while the presence of zinc ions was found to be essential for the interaction of UMSBP with DNA, UMSBP oligomerization occurred through zinc-depleted, unfolded zinc finger domains. Site directed mutagenesis analysis of UMSBP suggested that its unique methionine residue, which can be oxidized into methionine sulfoxide, is not involved in the redox-mediated regulation of UMSBP-DNA interactions.
- Published
- 2009
- Full Text
- View/download PDF
16. Enzymatic mechanism controls redox-mediated protein-DNA interactions at the replication origin of kinetoplast DNA minicircles.
- Author
-
Sela D, Yaffe N, and Shlomai J
- Subjects
- Amino Acid Sequence, Animals, Cell Cycle, Crithidia fasciculata genetics, Crithidia fasciculata metabolism, DNA-Binding Proteins chemistry, DNA-Binding Proteins genetics, Molecular Sequence Data, NADH, NADPH Oxidoreductases genetics, Nucleoproteins metabolism, Oxidation-Reduction, Protein Binding, Protozoan Proteins chemistry, Protozoan Proteins genetics, Trypanosoma cruzi enzymology, Trypanosoma cruzi genetics, DNA, Kinetoplast genetics, DNA-Binding Proteins metabolism, NADH, NADPH Oxidoreductases metabolism, Protozoan Proteins metabolism, Replication Origin genetics
- Abstract
Kinetoplast DNA (kDNA) is the mitochondrial DNA of trypanosomatids. Its major components are several thousand topologically interlocked DNA minicircles. Their replication origins are recognized by universal minicircle sequence-binding protein (UMSBP), a CCHC-type zinc finger protein, which has been implicated with minicircle replication initiation and kDNA segregation. Interactions of UMSBP with origin sequences in vitro have been found to be affected by the protein's redox state. Reduction of UMSBP activates its binding to the origin, whereas UMSBP oxidation impairs this activity. The role of redox in the regulation of UMSBP in vivo was studied here in synchronized cell cultures, monitoring both UMSBP origin binding activity and its redox state, throughout the trypanosomatid cell cycle. These studies indicated that UMSBP activity is regulated in vivo through the cell cycle dependent control of the protein's redox state. The hypothesis that UMSBP's redox state is controlled by an enzymatic mechanism, which mediates its direct reduction and oxidation, was challenged in a multienzyme reaction, reconstituted with pure enzymes of the trypanosomal major redox-regulating pathway. Coupling in vitro of this reaction with a UMSBP origin-binding reaction revealed the regulation of UMSBP activity through the opposing effects of tryparedoxin and tryparedoxin peroxidase. In the course of this reaction, tryparedoxin peroxidase directly oxidizes UMSBP, revealing a novel regulatory mechanism for the activation of an origin-binding protein, based on enzyme-mediated reversible modulation of the protein's redox state. This mode of regulation may represent a regulatory mechanism, functioning as an enzyme-mediated, redox-based biological switch.
- Published
- 2008
- Full Text
- View/download PDF
17. Unique characteristics of the kinetoplast DNA replication machinery provide potential drug targets in trypanosomatids.
- Author
-
Sela D, Milman N, Kapeller I, Zick A, Bezalel R, Yaffe N, and Shlomai J
- Subjects
- Animals, DNA Replication drug effects, DNA Replication physiology, DNA, Kinetoplast biosynthesis, DNA, Kinetoplast drug effects, Kinetoplastida drug effects, Kinetoplastida genetics, Trypanocidal Agents pharmacology
- Published
- 2008
- Full Text
- View/download PDF
18. Membrane depolarization combined with release of calcium from internal stores does not trigger secretion from PC 12 cells.
- Author
-
Ashery U, Weiss C, Sela D, Spira ME, and Atlas D
- Subjects
- Animals, Bradykinin pharmacology, Calcium Channels metabolism, Dopamine pharmacology, Intracellular Fluid metabolism, Membrane Potentials, PC12 Cells, Potassium pharmacology, Calcium metabolism, Norepinephrine metabolism
- Abstract
The mechanisms underlying catecholamine release from pheochromocytoma (PC 12) cells were examined. Whereas application of 1 microM bradykinin (BK) induced an increase in intracellular calcium ([Ca2+])i), either in medium containing 1.8 mM Ca2+ or in medium prepared without the addition of CaCl2 ("Ca(2+)-free medium"), norepinephrine ([3H]NE) release was induced only in Ca(2+)-containing medium. Similarly depolarization by 50 mM potassium induced [3H]NE release only in 1.8 mM calcium-containing medium. The combination of membrane depolarization (50 mM KCl) with increased [Ca2+]i secondary to BK application in "Ca(2+)-free medium" did not induce catecholamine secretion. It was concluded that Ca2+ entry through calcium channels at the plasma membrane is essential for the activation of catecholamine release. A rise in [Ca2+]i (4-5 times x basal) released from internal stores is not sufficient to trigger secretion from PC 12 cells, either by itself or in combination with membrane depolarization.
- Published
- 1993
19. ATP receptor. A putative receptor-operated channel in PC-12 cells.
- Author
-
Sela D, Ram E, and Atlas D
- Subjects
- Animals, Calcium metabolism, Cations, Divalent, Dopamine metabolism, Exocytosis, Magnesium metabolism, Nifedipine pharmacology, PC12 Cells, Rats, Verapamil metabolism, Calcium Channels metabolism, Receptors, Purinergic metabolism
- Abstract
External ATP induces [3H] dopamine [( 3H]DA) release in rat pheochromocytoma cells (PC-12 cells). The ATP-induced release is a saturable process with half-effective concentration of EC50 = 80 microM. ADP is a poor secretagogue of [3H]DA (one-sixth of ATP) and AMP is devoid of secretory capabilities. Adenosine and the non-hydrolyzable analogues of ATP, AppNHp and AppCp are ineffective as inducers of [3H]DA, release, or as inhibitors of the ATP-induced [3H]DA release. The most potent antagonist of ATP-induced release is Coomassie Blue (IC50 = 25 microM), compared to ADP beta S (IC50 = 500 microM). The overall rank order of potency is ATP greater than ADP much greater than AMP greater than adenosine, which is characteristic of the P2-purinergic receptor. ATP-induced secretion is absolutely Ca2+ dependent, indicating an exocytotic process and is independent of Mg2+ (up to 2 mM) suggesting that the active species is not ATP4-. (a) The ATP-induced 45Ca2+ influx into the cells is in good correlation to ATP induction of release (IC50 = 80 and 90 microM, respectively) and is carried over to ADP which has a diminished ability to induce both release and 45Ca2+ influx. (b) Divalent cations (Ba2+ greater than Sr2+ greater than Ln3+ greater than Mn2+) replace Ca2+ and support ATP-induced release similar to their effectiveness in supporting bradykinin- and K+ (50 mM)-induced release in PC-12 cells (Weiss, C., Sela, D., and Atlas, D. (1990) Neurosci. Lett. 119, 241-245). Combined together the absolute requirement of [Ca2+]ex for release, inhibition of release by Gd3+ (IC50 = 100 microM), Ni2+, and Co2+ (IC50 = 1 mM), and support of release by Ba2+, Sr2+, and Mn2+, we suggest that ATP induces Ca2+ entry via ligand-operated Ca2+ channels as previously suggested for ATP in smooth muscle cells (Benham, C.D., Bolton, T.B., Byren, N.G., and Large, W.A. (1987) J. Physiol. (Lond.) 387, 473-488). No significant inhibition by 1 microM verapamil, 10 microM nifedipine, or 2 mM Cd2+ argues against ATP activation of voltage-dependent Ca2+ channels as similarly shown for ATP-induced [3H]noradrenaline release (Inoue, K., Nakazawa, K., Fujimoro, K., and Takanaka, A. (1989) Neurosci. Lett. 106, 294-299). Thus, the widely distributed ATP receptor might play an essential role in Ca2+ homeostasis of the cell by introducing Ca2+ into the cell via specific ligand-gated Ca2+ channels.
- Published
- 1991
20. Divalent cations effectively replace Ca2+ and support bradykinin induced noradrenaline release.
- Author
-
Weiss C, Sela D, and Atlas D
- Subjects
- Adrenal Gland Neoplasms pathology, Animals, Osmolar Concentration, Pheochromocytoma pathology, Potassium pharmacology, Tumor Cells, Cultured, Adrenal Gland Neoplasms metabolism, Bradykinin pharmacology, Calcium pharmacology, Cations, Divalent pharmacology, Norepinephrine metabolism, Pheochromocytoma metabolism
- Abstract
Bradykinin (BK), a nonapeptide acting at the B2-type BK-receptor, and depolarization with high KCl (50 mM), induce catecholamine secretion in pheochromocytoma cells (PC-12). The mechanism underlying the BK-induced release, which is absolutely Ca2(+)-dependent, is not yet understood. Alkaline metals, barium (Ba2+), strontium (Sr2+) and other metal cations, manganese (Mn2+) or lanthanum (La3+), support BK-induced [3H]noradrenaline ([3H]NA) release. The extent of supporting transmitter release is dependent upon the specificity of the extracellular cation, with rank order potency of: Ba2+ greater than Sr2+ greater than Ca2+ greater than Mn2+La3+. The same rank order potency was observed for supporting both BK- and K(+)-induced release. [3H]NA release in the presence of Ba2+ or Sr2+ was much greater than in the presence of Ca2+, and unlike with Ca2+ was not saturable at the highest concentration measured. La3+ and Mn2+ were significantly less effective than Ca2+ at supporting release. These results strongly suggest that extracellular Ca2+ entry is essential for release, and that BK mediates release via a receptor-operated Ca2+ channel.
- Published
- 1990
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.