1
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Dudem S, Boon PX, Mullins N, McClafferty H, Shipston MJ, Wilkinson RDA, Lobb I, Sergeant GP, Thornbury KD, Tikhonova IG, Hollywood MA. Oxidation modulates LINGO2-induced inactivation of large conductance, Ca 2+-activated potassium channels. J Biol Chem 2023; 299:102975. [PMID: 36738787 PMCID: PMC10020666 DOI: 10.1016/j.jbc.2023.102975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Revised: 01/27/2023] [Accepted: 01/29/2023] [Indexed: 02/05/2023] Open
Abstract
Ca2+ and voltage-activated K+ (BK) channels are ubiquitous ion channels that can be modulated by accessory proteins, including β, γ, and LINGO1 BK subunits. In this study, we utilized a combination of site-directed mutagenesis, patch clamp electrophysiology, and molecular modeling to investigate if the biophysical properties of BK currents were affected by coexpression of LINGO2 and to examine how they are regulated by oxidation. We demonstrate that LINGO2 is a regulator of BK channels, since its coexpression with BK channels yields rapid inactivating currents, the activation of which is shifted ∼-30 mV compared to that of BKα currents. Furthermore, we show the oxidation of BK:LINGO2 currents (by exposure to epifluorescence illumination or chloramine-T) abolished inactivation. The effect of illumination depended on the presence of GFP, suggesting that it released free radicals which oxidized cysteine or methionine residues. In addition, the oxidation effects were resistant to treatment with the cysteine-specific reducing agent DTT, suggesting that methionine rather than cysteine residues may be involved. Our data with synthetic LINGO2 tail peptides further demonstrate that the rate of inactivation was slowed when residues M603 or M605 were oxidized, and practically abolished when both were oxidized. Taken together, these data demonstrate that both methionine residues in the LINGO2 tail mediate the effect of oxidation on BK:LINGO2 channels. Our molecular modeling suggests that methionine oxidation reduces the lipophilicity of the tail, thus preventing it from occluding the pore of the BK channel.
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Affiliation(s)
- Srikanth Dudem
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Louth, Ireland
| | - Pei Xin Boon
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Louth, Ireland
| | - Nicholas Mullins
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Louth, Ireland
| | - Heather McClafferty
- Centre for Discovery Brain Sciences, University of Edinburgh, Scotland, United Kingdom
| | - Michael J Shipston
- Centre for Discovery Brain Sciences, University of Edinburgh, Scotland, United Kingdom
| | | | - Ian Lobb
- Almac Discovery Ltd, Health Sciences Building, Belfast, NIR, United Kingdom
| | - Gerard P Sergeant
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Louth, Ireland
| | - Keith D Thornbury
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Louth, Ireland
| | - Irina G Tikhonova
- School of Pharmacy, Queen's University of Belfast, NIR, United Kingdom
| | - Mark A Hollywood
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Louth, Ireland.
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2
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Zavaritskaya O, Dudem S, Ma D, Rabab KE, Albrecht S, Tsvetkov D, Kassmann M, Thornbury K, Mladenov M, Kammermeier C, Sergeant G, Mullins N, Wouappi O, Wurm H, Kannt A, Gollasch M, Hollywood MA, Schubert R. Vasodilation of rat skeletal muscle arteries by the novel BK channel opener GoSlo is mediated by the simultaneous activation of BK and K v 7 channels. Br J Pharmacol 2020; 177:1164-1186. [PMID: 31658366 PMCID: PMC7042121 DOI: 10.1111/bph.14910] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 09/27/2019] [Accepted: 10/01/2019] [Indexed: 01/17/2023] Open
Abstract
Background and Purpose BK channels play important roles in various physiological and pathophysiological processes and thus have been the target of several drug development programmes focused on creating new efficacious BK channel openers, such as the GoSlo‐SR compounds. However, the effect of GoSlo‐SR compounds on vascular smooth muscle has not been studied. Therefore, we tested the hypothesis that GoSlo‐SR compounds dilate arteries exclusively by activating BK channels. Experimental Approach Experiments were performed on rat Gracilis muscle, saphenous, mesenteric and tail arteries using isobaric and isometric myography, sharp microelectrodes, digital droplet PCR and the patch‐clamp technique. Key Results GoSlo‐SR compounds dilated isobaric and relaxed and hyperpolarised isometric vessel preparations and their effects were abolished after (a) functionally eliminating K+ channels by pre‐constriction with 50 mM KCl or (b) blocking all K+ channels known to be expressed in vascular smooth muscle. However, these effects were not blocked when BK channels were inhibited. Surprisingly, the Kv7 channel inhibitor XE991 reduced their effects considerably, but neither Kv1 nor Kv2 channel blockers altered the inhibitory effects of GoSlo‐SR. However, the combined blockade of BK and Kv7 channels abolished the GoSlo‐SR‐induced relaxation. GoSlo‐SR compounds also activated Kv7.4 and Kv7.5 channels expressed in HEK 293 cells. Conclusion and Implications This study shows that GoSlo‐SR compounds are effective relaxants in vascular smooth muscle and mediate their effects by a combined activation of BK and Kv7.4/Kv7.5 channels. Activation of Kv1, Kv2 or Kv7.1 channels or other vasodilator pathways seems not to be involved.
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Affiliation(s)
- Olga Zavaritskaya
- Centre for Biomedicine and Medical Technology Mannheim (CBTM), Research Division Cardiovascular Physiology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Srikanth Dudem
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Dongyu Ma
- Centre for Biomedicine and Medical Technology Mannheim (CBTM), Research Division Cardiovascular Physiology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany.,Department of Cardiology, The First Affiliated Hospital of Anhui Medical University, Anhui, China
| | - Kaneez E Rabab
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Sarah Albrecht
- Centre for Biomedicine and Medical Technology Mannheim (CBTM), Research Division Cardiovascular Physiology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Dmitry Tsvetkov
- Experimental and Clinical Research Center (ECRC), a joint cooperation between the Charité Medical Faculty and the Max Delbrück Center for Molecular Medicine (MDC), Berlin, Germany
| | - Mario Kassmann
- Experimental and Clinical Research Center (ECRC), a joint cooperation between the Charité Medical Faculty and the Max Delbrück Center for Molecular Medicine (MDC), Berlin, Germany
| | - Keith Thornbury
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland.,Ion Channel Biotechnology Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Mitko Mladenov
- Centre for Biomedicine and Medical Technology Mannheim (CBTM), Research Division Cardiovascular Physiology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany.,Institute of Biology, Faculty of Natural Sciences and Mathematics, Sts. Cyril and Methodius, University of Skopje, Skopje, Macedonia.,Department of Fundamental and Applied Physiology, Russian National Research Medical University, Moscow, Russia
| | - Claire Kammermeier
- Sanofi Diabetes Research, Industriepark Hoechst, Frankfurt am Main, Germany
| | - Gerard Sergeant
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland.,Ion Channel Biotechnology Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Nicholas Mullins
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Ornella Wouappi
- Centre for Biomedicine and Medical Technology Mannheim (CBTM), Research Division Cardiovascular Physiology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Hannah Wurm
- Centre for Biomedicine and Medical Technology Mannheim (CBTM), Research Division Cardiovascular Physiology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Aimo Kannt
- Sanofi Diabetes Research, Industriepark Hoechst, Frankfurt am Main, Germany.,Institute of Experimental and Clinical Pharmacology and Toxicology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Maik Gollasch
- Experimental and Clinical Research Center (ECRC), a joint cooperation between the Charité Medical Faculty and the Max Delbrück Center for Molecular Medicine (MDC), Berlin, Germany
| | - Mark A Hollywood
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland.,Ion Channel Biotechnology Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Rudolf Schubert
- Centre for Biomedicine and Medical Technology Mannheim (CBTM), Research Division Cardiovascular Physiology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany.,Faculty of Medicine, Department of Physiology, Augsburg University, Augsburg, Germany
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3
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Van der Auwera S, Peyrot WJ, Milaneschi Y, Hertel J, Baune BT, Breen G, Byrne EM, Dunn EC, Fisher HL, Homuth G, Levinson DF, Lewis CM, Mills N, Mullins N, Nauck M, Pistis G, Preisig M, Rietschel M, Ripke S, Sullivan PF, Teumer A, Völzke H, Boomsma DI, Wray NR, Penninx BWJH, Grabe HJ. Genome-wide gene-environment interaction in depression: A systematic evaluation of candidate genes: The childhood trauma working-group of PGC-MDD. Am J Med Genet B Neuropsychiatr Genet 2018; 177:40-49. [PMID: 29159863 PMCID: PMC5726923 DOI: 10.1002/ajmg.b.32593] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Revised: 06/28/2017] [Accepted: 08/08/2017] [Indexed: 12/16/2022]
Abstract
Gene by environment (GxE) interaction studies have investigated the influence of a number of candidate genes and variants for major depressive disorder (MDD) on the association between childhood trauma and MDD. Most of these studies are hypothesis driven and investigate only a limited number of SNPs in relevant pathways using differing methodological approaches. Here (1) we identified 27 genes and 268 SNPs previously associated with MDD or with GxE interaction in MDD and (2) analyzed their impact on GxE in MDD using a common approach in 3944 subjects of European ancestry from the Psychiatric Genomics Consortium who had completed the Childhood Trauma Questionnaire. (3) We subsequently used the genome-wide SNP data for a genome-wide case-control GxE model and GxE case-only analyses testing for an enrichment of associated SNPs. No genome-wide significant hits and no consistency among the signals of the different analytic approaches could be observed. This is the largest study for systematic GxE interaction analysis in MDD in subjects of European ancestry to date. Most of the known candidate genes/variants could not be supported. Thus, their impact on GxE interaction in MDD may be questionable. Our results underscore the need for larger samples, more extensive assessment of environmental exposures, and greater efforts to investigate new methodological approaches in GxE models for MDD.
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Affiliation(s)
| | - S Van der Auwera
- Department of Psychiatry and Psychotherapy, University Medicine Greifswald, Greifswald, Germany
| | - WJ Peyrot
- Department of Psychiatry, Vrije Universiteit Medical Center and GGZ in Geest, Amsterdam, The Netherlands
| | - Y Milaneschi
- Department of Psychiatry, Vrije Universiteit Medical Center and GGZ in Geest, Amsterdam, The Netherlands
| | - J Hertel
- Department of Psychiatry and Psychotherapy, University Medicine Greifswald, Greifswald, Germany
| | - BT Baune
- Discipline of Psychiatry, University of Adelaide, Adelaide, Australia
| | - G Breen
- MRC Social Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, Great Britain,NIHR BRC for Mental Health, King's College London, London, Great Britain
| | - EM Byrne
- Queensland Brain Institute, The University of Queensland, Brisbane, Australia
| | - EC Dunn
- Stanley Center for Psychiatric Research, Broad Institute, Cambridge, US,Department of Psychiatry, Massachusetts General Hospital, Boston, US,Psychiatric and Neurodevelopmental Genetics Unit (PNGU), Massachusetts General Hospital, Boston, US
| | - HL Fisher
- MRC Social Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, Great Britain
| | - G Homuth
- Interfaculty Institute for Genetics and Functional Genomics, Department of Functional Genomics, University Medicine and Ernst Moritz Arndt University Greifswald, Greifswald, Germany
| | - DF Levinson
- Psychiatry & Behavioral Sciences, Stanford University, Stanford, US
| | - CM Lewis
- MRC Social Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, Great Britain,Department of Medical & Molecular Genetics, King's College London, London, Great Britain
| | - N Mills
- Discipline of Psychiatry, University of Adelaide, Adelaide, Australia
| | - N Mullins
- MRC Social Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, Great Britain
| | - M Nauck
- DZHK (German Centre for Cardiovascular Research), Partner Site Greifswald, University Medicine Greifswald, Greifswald, Germany,Institute of Clinical Chemistry and Laboratory Medicine, University Medicine Greifswald, Greifswald, Germany
| | - G Pistis
- Department of Psychiatry, University Hospital of Lausanne, Prilly, Switzerland
| | - M Preisig
- Department of Psychiatry, University Hospital of Lausanne, Prilly, Switzerland
| | - M Rietschel
- Department of Genetic Epidemiology in Psychiatry, Central Institute of Mental Health, Mannheim, Germany
| | - S Ripke
- Medical and Population Genetics, Broad Institute, Cambridge, US,Analytic and Translational Genetics Unit, Massachusetts General Hospital, Boston, US,Department of Psychiatry and Psychotherapy, University medicine Berlin Campus Charité Mitte, Berlin, Germany
| | - PF Sullivan
- Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden,Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, US,Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, US
| | - A Teumer
- Institute for Community Medicine, University Medicine Greifswald, Greifswald, Germany
| | - H Völzke
- Institute for Community Medicine, University Medicine Greifswald, Greifswald, Germany
| | | | - DI Boomsma
- Dept of Biological Psychology & EMGO+ Institute for Health and Care Research, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - NR Wray
- Queensland Brain Institute, The University of Queensland, Brisbane, Australia,Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
| | - BWJH Penninx
- Department of Psychiatry, Vrije Universiteit Medical Center and GGZ in Geest, Amsterdam, The Netherlands
| | - HJ Grabe
- Department of Psychiatry and Psychotherapy, University Medicine Greifswald, Greifswald, Germany
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4
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Mullins N, Power RA, Fisher HL, Hanscombe KB, Euesden J, Iniesta R, Levinson DF, Weissman MM, Potash JB, Shi J, Uher R, Cohen-Woods S, Rivera M, Jones L, Jones I, Craddock N, Owen MJ, Korszun A, Craig IW, Farmer AE, McGuffin P, Breen G, Lewis CM. Polygenic interactions with environmental adversity in the aetiology of major depressive disorder. Psychol Med 2016; 46:759-770. [PMID: 26526099 PMCID: PMC4754832 DOI: 10.1017/s0033291715002172] [Citation(s) in RCA: 114] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Revised: 09/22/2015] [Accepted: 09/22/2015] [Indexed: 12/30/2022]
Abstract
BACKGROUND Major depressive disorder (MDD) is a common and disabling condition with well-established heritability and environmental risk factors. Gene-environment interaction studies in MDD have typically investigated candidate genes, though the disorder is known to be highly polygenic. This study aims to test for interaction between polygenic risk and stressful life events (SLEs) or childhood trauma (CT) in the aetiology of MDD. METHOD The RADIANT UK sample consists of 1605 MDD cases and 1064 controls with SLE data, and a subset of 240 cases and 272 controls with CT data. Polygenic risk scores (PRS) were constructed using results from a mega-analysis on MDD by the Psychiatric Genomics Consortium. PRS and environmental factors were tested for association with case/control status and for interaction between them. RESULTS PRS significantly predicted depression, explaining 1.1% of variance in phenotype (p = 1.9 × 10(-6)). SLEs and CT were also associated with MDD status (p = 2.19 × 10(-4) and p = 5.12 × 10(-20), respectively). No interactions were found between PRS and SLEs. Significant PRSxCT interactions were found (p = 0.002), but showed an inverse association with MDD status, as cases who experienced more severe CT tended to have a lower PRS than other cases or controls. This relationship between PRS and CT was not observed in independent replication samples. CONCLUSIONS CT is a strong risk factor for MDD but may have greater effect in individuals with lower genetic liability for the disorder. Including environmental risk along with genetics is important in studying the aetiology of MDD and PRS provide a useful approach to investigating gene-environment interactions in complex traits.
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Affiliation(s)
- N. Mullins
- MRC Social, Genetic and Developmental Psychiatry
Centre, Institute of Psychiatry, Psychology &
Neuroscience, King's College London,
London, UK
| | - R. A. Power
- MRC Social, Genetic and Developmental Psychiatry
Centre, Institute of Psychiatry, Psychology &
Neuroscience, King's College London,
London, UK
| | - H. L. Fisher
- MRC Social, Genetic and Developmental Psychiatry
Centre, Institute of Psychiatry, Psychology &
Neuroscience, King's College London,
London, UK
| | - K. B. Hanscombe
- Division of Genetics and Molecular
Medicine, King's College London School of Medicine,
Guy's Hospital, London,
UK
| | - J. Euesden
- MRC Social, Genetic and Developmental Psychiatry
Centre, Institute of Psychiatry, Psychology &
Neuroscience, King's College London,
London, UK
| | - R. Iniesta
- MRC Social, Genetic and Developmental Psychiatry
Centre, Institute of Psychiatry, Psychology &
Neuroscience, King's College London,
London, UK
| | - D. F. Levinson
- Department of Psychiatry and Behavioral
Sciences, Stanford University, Stanford,
CA, USA
| | - M. M. Weissman
- Department of Psychiatry,
Columbia University and New York State Psychiatric Institute,
New York, NY, USA
| | - J. B. Potash
- Department of Psychiatry,
University of Iowa, Iowa City, IA,
USA
| | - J. Shi
- Division of Cancer Epidemiology and
Genetics, National Cancer Institute,
Bethesda, MD, USA
| | - R. Uher
- MRC Social, Genetic and Developmental Psychiatry
Centre, Institute of Psychiatry, Psychology &
Neuroscience, King's College London,
London, UK
- Department of Psychiatry,
Dalhousie University, Halifax,
Nova Scotia, Canada
| | - S. Cohen-Woods
- Discipline of Psychiatry,
School of Medicine, University of
Adelaide, Adelaide, South
Australia, Australia
| | - M. Rivera
- MRC Social, Genetic and Developmental Psychiatry
Centre, Institute of Psychiatry, Psychology &
Neuroscience, King's College London,
London, UK
- CIBERSAM-University of Granada and Instituto de
Investigación Biosanitaria ibs.GRANADA, Hospitales Universitarios
de Granada/Universidad de Granada, Granada,
Spain
| | - L. Jones
- Department of Psychiatry,
School of Clinical and Experimental Medicine,
University of Birmingham, Birmingham,
UK
| | - I. Jones
- MRC Centre for Neuropsychiatric Genetics and
Genomics, Neuroscience and Mental Health Research
Institute, Cardiff University,
Cardiff, UK
| | - N. Craddock
- MRC Centre for Neuropsychiatric Genetics and
Genomics, Neuroscience and Mental Health Research
Institute, Cardiff University,
Cardiff, UK
| | - M. J. Owen
- MRC Centre for Neuropsychiatric Genetics and
Genomics, Neuroscience and Mental Health Research
Institute, Cardiff University,
Cardiff, UK
| | - A. Korszun
- Barts and The London Medical School,
Queen Mary University of London, London,
UK
| | - I. W. Craig
- MRC Social, Genetic and Developmental Psychiatry
Centre, Institute of Psychiatry, Psychology &
Neuroscience, King's College London,
London, UK
| | - A. E. Farmer
- MRC Social, Genetic and Developmental Psychiatry
Centre, Institute of Psychiatry, Psychology &
Neuroscience, King's College London,
London, UK
| | - P. McGuffin
- MRC Social, Genetic and Developmental Psychiatry
Centre, Institute of Psychiatry, Psychology &
Neuroscience, King's College London,
London, UK
| | - G. Breen
- MRC Social, Genetic and Developmental Psychiatry
Centre, Institute of Psychiatry, Psychology &
Neuroscience, King's College London,
London, UK
- NIHR Biomedical Research Centre for Mental
Health, South London and Maudsley NHS Foundation Trust and Institute
of Psychiatry, Psychology & Neuroscience, King's College
London, London, UK
| | - C. M. Lewis
- MRC Social, Genetic and Developmental Psychiatry
Centre, Institute of Psychiatry, Psychology &
Neuroscience, King's College London,
London, UK
- Division of Genetics and Molecular
Medicine, King's College London School of Medicine,
Guy's Hospital, London,
UK
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5
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Murphy TM, Mullins N, Ryan M, Foster T, Kelly C, McClelland R, O'Grady J, Corcoran E, Brady J, Reilly M, Jeffers A, Brown K, Maher A, Bannan N, Casement A, Lynch D, Bolger S, Buckley A, Quinlivan L, Daly L, Kelleher C, Malone KM. Genetic variation in DNMT3B and increased global DNA methylation is associated with suicide attempts in psychiatric patients. Genes Brain Behav 2013; 12:125-32. [PMID: 23025623 DOI: 10.1111/j.1601-183x.2012.00865.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Revised: 08/17/2012] [Accepted: 09/27/2012] [Indexed: 11/28/2022]
Abstract
Recently, a significant epigenetic component in the pathology of suicide has been realized. Here we investigate candidate functional SNPs in epigenetic-regulatory genes, DNMT1 and DNMT3B, for association with suicide attempt (SA) among patients with co-existing psychiatric illness. In addition, global DNA methylation levels [5-methyl cytosine (5-mC%)] between SA and psychiatric controls were quantified using the Methylflash Methylated DNA Quantification Kit. DNA was obtained from blood of 79 suicide attempters and 80 non-attempters, assessed for DSM-IV Axis I disorders. Functional SNPs were selected for each gene (DNMT1; n = 7, DNMT3B; n = 10), and genotyped. A SNP (rs2424932) residing in the 3' UTR of the DNMT3B gene was associated with SA compared with a non-attempter control group (P = 0.001; Chi-squared test, Bonferroni adjusted P value = 0.02). Moreover, haplotype analysis identified a DNMT3B haplotype which differed between cases and controls, however this association did not hold after Bonferroni correction (P = 0.01, Bonferroni adjusted P value = 0.56). Global methylation analysis showed that psychiatric patients with a history of SA had significantly higher levels of global DNA methylation compared with controls (P = 0.018, Student's t-test). In conclusion, this is the first report investigating polymorphisms in DNMT genes and global DNA methylation quantification in SA risk. Preliminary findings suggest that allelic variability in DNMT3B may be relevant to the underlying diathesis for suicidal acts and our findings support the hypothesis that aberrant DNA methylation profiles may contribute to the biology of suicidal acts. Thus, analysis of global DNA hypermethylation in blood may represent a biomarker for increased SA risk in psychiatric patients.
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Affiliation(s)
- T M Murphy
- Department of Psychiatry and Mental Health Research & Education and Research Centre, St Vincent's University Hospital, and School of Medicine & Medical Science, University College Dublin, Dublin 4, Ireland
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6
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ElShamy WM, Gardner L, Malik R, Shimizu Y, Mullins N. P3-01-01: Geminin Overexpression Prevents the Completion of Topoisomerase IIa Chromosome Decatenation Leading to Aneuploidy in Human Mammary Epithelial Cells. Cancer Res 2011. [DOI: 10.1158/0008-5472.sabcs11-p3-01-01] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Topoisomerase IIα (TopoIIα) cleaves DNA in a reversible manner, making it a valuable target for agents such as etoposide that trap the enzyme in a covalent bond with the DNA end it cleaves and prevents DNA re-ligation and triggers cell death in cancer cells. However, development of resistance to these agents limits their therapeutic use. In this study, we examined therapeutic targeting of geminin for improving the therapeutic potential of TopoIIa agents.
Human mammary epithelial (HME) and breast cancer cell lines were used. Geminin, TopoIIα, Cdc7 silencing was done using specific siRNAs. Transit or stable inducible overexpression of these proteins and CKI∈ were also used, as well as several pharmacological inhibitors that target TopoIIα, Cdc7, or CKI∈. We manipulated
HME cells expressing H2B-GFP, in order to detect chromosome bridges. Immunoprecipitation and direct western blot were used to detect interactions between these proteins and their total expression, respectively, whereas interactions on chromosomal arms were detected using the TARDIS assay. TopoIIα phosphorylation by Cdc7 or CKI∈ was done using in vitro kinase assay. The TopoGen decatenation kit was used to measure TopoIIα decatenation activity. Finally, comet assay and metaphase chromosome spread were used to detect chromosome breakages and changes in chromosome condensation or numbers, respectively.
We found that geminin and TopoIIα interact in G2/M/early G1 cells on chromosomes, that geminin recruits TopoIIα to chromosomal decatenation sites or vice versa, and that geminin silencing in HME cells triggers the formation of chromosome bridges through suppressing TopoIIα access to chromosomal arms. CKIε kinase phosphorylates and positively regulates TopoIIα chromosome localization and function. CKIε kinase overexpression or Cdc7 kinase silencing (also phosphorylates TopoIIα in vitro), restored DNA decatenation and chromosome segregation in geminin-silenced cells before triggering cell death. In vivo, at normal concentration, geminin recruits the desumoylating enzymes SENP1 and SENP2 to desumoylate chromosomal bound TopoIIα and promote its release from chromosomes following completion of DNA decatenation. In cells overexpressing geminin, premature departure of TopoIIα from chromosomes is thought to be due to the fact that geminin recruits more of these desumoylating enzymes, or recruits them earlier, to chromosomal bound TopoIIα. This triggers premature release of TopoIIα from chromosomes, which we propose induces aneuploidy in HME cells, since chromosome breakages generated through were not sensed and/or repaired and the cell cycle was not arrested. TopoIIα recruitment and its chromosome decatenation function require normal level of geminin. Geminin silencing induces a cytokinetic checkpoint in which Cdc7 phosphorylates TopoIIα and inhibits its chromosomal recruitment and decatenation function. Geminin overexpression prematurely desumoylates TopoIIα, triggering its premature departure from chromosomes and leading to chromosomal abnormalities and the formation of aneuploid, drug resistant cancer cells. We propose that therapeutic targeting of geminin is essential for improving the therapeutic potential of TopoIIα agents.
Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P3-01-01.
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Affiliation(s)
- WM ElShamy
- 1University of Mississippi Medical Center, Jackson, MS
| | - L Gardner
- 1University of Mississippi Medical Center, Jackson, MS
| | - R Malik
- 1University of Mississippi Medical Center, Jackson, MS
| | - Y Shimizu
- 1University of Mississippi Medical Center, Jackson, MS
| | - N Mullins
- 1University of Mississippi Medical Center, Jackson, MS
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7
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Kudjawu Y, Lévy-Bruhl D, Celentano LP, O'Flanagan D, Salmaso S, Lopalco P, Mullins N, Bacci S. The current status of HPV and rotavirus vaccines in national immunisation schedules in the EU – preliminary results of a VENICE survey. ACTA ACUST UNITED AC 2007; 12:E070426.1. [PMID: 17868608 DOI: 10.2807/esw.12.17.03181-en] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In the second half of 2006, two vaccines against rotavirus infections and one against human papillomavirus (HPV) infection were granted licensing authorisations by the European Medicines Agency (EMEA).
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Affiliation(s)
- Y Kudjawu
- Institut de Veille Sanitaire, Paris, France
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Snow DM, Mullins N, Hynds DL. Nervous system-derived chondroitin sulfate proteoglycans regulate growth cone morphology and inhibit neurite outgrowth: a light, epifluorescence, and electron microscopy study. Microsc Res Tech 2001; 54:273-86. [PMID: 11514984 DOI: 10.1002/jemt.1140] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Proteoglycans influence aging and plasticity in the nervous system. Particularly prominent are the chondroitin sulfate proteoglycans (CSPGs), which are generally inhibitory to neurite outgrowth. During development, CSPGs facilitate normal guidance, but following nervous system injury and in diseases of aging (e.g., Alzheimer's disease), they block successful regeneration, and are associated with axon devoid regions and degenerating nerve cells. Whereas previous studies used non-nervous system sources of CSPGs, this study analyzed the morphology and behavior of sensory (dorsal root ganglia) neurons, and a human nerve cell model (SH-SY5Y neuroblastoma cells) as they contacted nervous system-derived CSPGs, using a variety of microscopy techniques. The results of these qualitative analyses show that growth cones of both nerve cell types contact CSPGs via actin-based filopodia, sample the CSPGs repeatedly without collapse, and alter their trajectory to avoid nervous system-derived CSPGs. Turning and branching are correlated with increased filopodial sampling, and are common to both neurons and Schwann cells. We show that CSPG expression by rat CNS astrocytes in culture is correlated with sensory neuron avoidance. Further, we show for the first time the ultrastructure of sensory growth cones at a CSPG-laminin border and reveal details of growth cone and neurite organization at this choice point. This type of detailed analysis of the response of growth cones to nervous system-derived CSPGs may lead to an understanding of CSPG function following injury and in diseases of aging, where CSPGs are likely to contribute to aberrant neurite outgrowth, failed or reduced synaptic connectivity, and/or ineffective plasticity.
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Affiliation(s)
- D M Snow
- Department of Anatomy and Neurobiology, University of Kentucky, Lexington, Kentucky 40536-0298, USA.
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Mullins N, Lee HH. Occupational exposure to HIV, hepatitis B, hepatitis C, and tuberculosis. Clin Podiatr Med Surg 1998; 15:363-79. [PMID: 9576059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
This article reviews risk of occupational exposure to bloodborne pathogens, specifically HIV, hepatitis B, and hepatitis C to healthcare workers. Information regarding assessing the risk of exposure, appropriate actions to take if an exposure occurs, the most recent recommendations for treatment and follow-up postexposure, and prevention strategies for avoiding exposure are presented. Additionally, current recommendations for the prevention of the transmission of tuberculosis in healthcare workers and the regulatory guidelines governing this topic are discussed.
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Affiliation(s)
- N Mullins
- California College of Podiatric Medicine, San Francisco, USA
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Abstract
During a two-year period, 133 isolates of clostridia from clinical courses were obtained. These isolates are reviewed as to clinical significance and antimicrobial susceptibility. Adequate charts were available on 63 patients, nine (14%) of whom had their clinical source significantly altered by the presence of clostridia. Clostridia of little or no clinical significance were isolated from blood cultures from six patients. The occurrence of clostridial infections is unpredictable, and adequate clinical information is necessary to determine the need for identification of clostridial isolates.
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