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Zufferey A, Ibberson M, Reny JL, Xenarios I, Sanchez JC, Fontana P. Unraveling modulators of platelet reactivity in cardiovascular patients using omics strategies: Towards a network biology paradigm. TRANSLATIONAL PROTEOMICS 2013. [DOI: 10.1016/j.trprot.2013.04.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
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Bahou WF. Platelet systems biology using integrated genetic and proteomic platforms. Thromb Res 2012; 129 Suppl 1:S38-45. [PMID: 22682131 DOI: 10.1016/s0049-3848(12)70014-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Platelets retain megakaryocyte-derived mRNA, an abundant and diverse array of miRNAs, and have evolved unique adaptive signals for maintenance of genetic and protein diversity. Quiescent platelets generally display minimal translational activity, although maximally-activated platelets retain the capacity for protein synthesis. Progressive data using multiple platelet activation models clearly demonstrate that platelet responses to the majority (if not all) agonists are highly variable within the population, demonstrating considerable heritability in siblings, twins, and families with premature coronary artery disease. Research from our laboratory has adapted global profiling strategies to close the knowledge gap currently existing between genetic variability and platelet phenotypic responsiveness. We have applied iterative algorithms for genetic biomarker discovery and class prediction models of platelet phenotypes, with the goal of systematically analyzing integrated mRNA/miRNA/proteomic datasets for identification of regulatory networks that define phenotypic variability in platelet responses. This approach has the potential to define platelet genetic biomarkers predictive of thrombohemorrhagic outcomes in both normal and widely disparate clinical conditions.
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Affiliation(s)
- Wadie F Bahou
- Department of Medicine, Stony Brook University, Stony Brook, NY 11794-8151, USA.
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53
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Xu AG, Xu RM, Lu CQ, Yao MY, Zhao W, Fu X, Guo J, Xu QF, Li DD. Correlation of von Willebrand factor gene polymorphism and coronary heart disease. Mol Med Rep 2012; 6:1107-10. [PMID: 22923007 DOI: 10.3892/mmr.2012.1037] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2012] [Accepted: 08/09/2012] [Indexed: 11/05/2022] Open
Abstract
To characterize von Willebrand factor (vWF) gene polymorphisms at site A1381T and the correlation of plasma vWF levels with coronary heart disease, the vWF genotypes at site A1381T were analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) in patients diagnosed with coronary heart disease and normal controls (n=110 per group), and plasma vWF levels were measured by enzyme‑linked immunosorbent assay. The results showed that the plasma vWF levels were higher in the experimental group than in the control group and had no association with gender (t=11.69, p<0.05). In the experimental group, the plasma vWF levels were higher in the patients with the AG genotype than in those with the GG genotype (p<0.05). In the control group, the plasma vWF levels of the subjects with blood type O were significantly lower than those of the individuals with other blood types (p<0.05). In the experimental group, all blood types had significantly higher plasma vWF levels than the control group and the difference was significant among different blood types (p<0.05). In summary, vWF gene polymorphisms at site A1381T were not associated with coronary heart disease, but plasma vWF levels were influenced by vWF gene polymorphisms at site A1381T, blood type and coronary heart disease.
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Affiliation(s)
- Ai-Guo Xu
- Department of Respiratory and Critical Care Medicine, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, PR China.
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Dusse F, Frey UH, Bilalic A, Dirkmann D, Görlinger K, Siffert W, Peters J. The GNB3 C825T polymorphism influences platelet aggregation in human whole blood. Pharmacogenet Genomics 2012; 22:43-9. [PMID: 22082654 DOI: 10.1097/fpc.0b013e32834e1674] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
BACKGROUND Platelet aggregation varies among individuals; and genetic factors may alter platelet activation through G-protein-coupled receptors, thus influencing results of point-of-care platelet aggregometry in whole blood. We tested the hypothesis that the C825T polymorphism of the gene GNB3 encoding the G-protein β-3 subunit and the platelet GPIIIa Pl(A1)/(A2) polymorphism of the glycoprotein IIIa influence platelet aggregation. METHODS Evoked [thrombin receptor activating peptide (TRAP), ADP, TXA(2) agonist U46619, epinephrine, and collagen] platelet aggregation in whole blood was measured using impedance aggregometry (Multiplate) in 143 healthy individuals (age: 40.2 years ±11.7 SD). Genotypes were determined using pyrosequencing and restriction analysis. Data were analyzed by linear one-way analysis of variance and Student's t-test, linear and multiple regression, and the χ(2)-test, as appropriate. RESULTS Homozygous carriers of the GNB3 825C-allele showed significantly (P≤0.022) increased maximum aggregation for EC(75) dosages compared with CT and TT genotypes [e.g. ADP: CC 150±36 vs. TT 126±33 aggregation unit (AU); thrombin receptor activating peptide: CC 175±46 vs. TT 150±38 AU; U46619: CC 164±33 vs. 149±32 AU; epinephrine: CC 66±41 vs. TT 48±34 AU]. In contrast, genotypes of glycoprotein IIb/IIIa PI(A)-polymorphism had no effect. Regression analysis revealed the GNB3 C825T polymorphism as an independent factor for enhanced platelet aggregation, besides factors such as female sex and blood cell values. CONCLUSION In human whole blood, the GNB3 825CC genotype is associated with enhanced platelet aggregation.
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Affiliation(s)
- Fabian Dusse
- Department of Anaesthesiology and Intensive Care Medicine, University Hospital, University of Duisburg-Essen, Essen, Germany.
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55
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Edelstein LC, Luna EJ, Gibson IB, Bray M, Jin Y, Kondkar A, Nagalla S, Hadjout-Rabi N, Smith TC, Covarrubias D, Jones SN, Ahmad F, Stolla M, Kong X, Fang Z, Bergmeier W, Shaw C, Leal SM, Bray PF. Human genome-wide association and mouse knockout approaches identify platelet supervillin as an inhibitor of thrombus formation under shear stress. Circulation 2012; 125:2762-71. [PMID: 22550155 DOI: 10.1161/circulationaha.112.091462] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND High shear force critically regulates platelet adhesion and thrombus formation during ischemic vascular events. To identify genetic factors that influence platelet thrombus formation under high shear stress, we performed a genome-wide association study and confirmatory experiments in human and animal platelets. METHODS AND RESULTS Closure times in the shear-dependent platelet function analyzer (PFA)-100 were measured on healthy, nondiabetic European Americans (n=125) and blacks (n=116). A genome-wide association (P<5×10(-8)) was identified with 2 single-nucleotide polymorphisms within the SVIL gene (chromosome 10p11.23) in African Americans but not European Americans. Microarray analyses of human platelet RNA demonstrated the presence of SVIL isoform 1 (supervillin) but not muscle-specific isoforms 2 and 3 (archvillin, SmAV). SVIL mRNA levels were associated with SVIL genotypes (P≤0.02) and were inversely correlated with PFA-100 closure times (P<0.04) and platelet volume (P<0.02). Leukocyte-depleted platelets contained abundant levels of the ≈205-kDa supervillin polypeptide. To assess functionality, mice lacking platelet supervillin were generated and back-crossed onto a C57BL/6 background. Compared with controls, murine platelets lacking supervillin were larger by flow cytometry and confocal microscopy and exhibited enhanced platelet thrombus formation under high-shear but not low-shear conditions. CONCLUSIONS We show for the first time that (1) platelets contain supervillin; (2) platelet thrombus formation in the PFA-100 is associated with human SVIL variants and low SVIL expression; and (3) murine platelets lacking supervillin exhibit enhanced platelet thrombus formation at high shear stress. These data are consistent with an inhibitory role for supervillin in platelet adhesion and arterial thrombosis.
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Affiliation(s)
- Leonard C Edelstein
- Cardeza Foundation for Hematologic Research, Department of Medicine, Jefferson Medical College, Thomas Jefferson University, Curtis Building, Room 324, 1015 Walnut St, Philadelphia, PA 19107, USA
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56
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Qayyum R, Snively BM, Ziv E, Nalls MA, Liu Y, Tang W, Yanek LR, Lange L, Evans MK, Ganesh S, Austin MA, Lettre G, Becker DM, Zonderman AB, Singleton AB, Harris TB, Mohler ER, Logsdon BA, Kooperberg C, Folsom AR, Wilson JG, Becker LC, Reiner AP. A meta-analysis and genome-wide association study of platelet count and mean platelet volume in african americans. PLoS Genet 2012; 8:e1002491. [PMID: 22423221 PMCID: PMC3299192 DOI: 10.1371/journal.pgen.1002491] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2011] [Accepted: 12/05/2011] [Indexed: 12/24/2022] Open
Abstract
Several genetic variants associated with platelet count and mean platelet volume (MPV) were recently reported in people of European ancestry. In this meta-analysis of 7 genome-wide association studies (GWAS) enrolling African Americans, our aim was to identify novel genetic variants associated with platelet count and MPV. For all cohorts, GWAS analysis was performed using additive models after adjusting for age, sex, and population stratification. For both platelet phenotypes, meta-analyses were conducted using inverse-variance weighted fixed-effect models. Platelet aggregation assays in whole blood were performed in the participants of the GeneSTAR cohort. Genetic variants in ten independent regions were associated with platelet count (N = 16,388) with p<5×10(-8) of which 5 have not been associated with platelet count in previous GWAS. The novel genetic variants associated with platelet count were in the following regions (the most significant SNP, closest gene, and p-value): 6p22 (rs12526480, LRRC16A, p = 9.1×10(-9)), 7q11 (rs13236689, CD36, p = 2.8×10(-9)), 10q21 (rs7896518, JMJD1C, p = 2.3×10(-12)), 11q13 (rs477895, BAD, p = 4.9×10(-8)), and 20q13 (rs151361, SLMO2, p = 9.4×10(-9)). Three of these loci (10q21, 11q13, and 20q13) were replicated in European Americans (N = 14,909) and one (11q13) in Hispanic Americans (N = 3,462). For MPV (N = 4,531), genetic variants in 3 regions were significant at p<5×10(-8), two of which were also associated with platelet count. Previously reported regions that were also significant in this study were 6p21, 6q23, 7q22, 12q24, and 19p13 for platelet count and 7q22, 17q11, and 19p13 for MPV. The most significant SNP in 1 region was also associated with ADP-induced maximal platelet aggregation in whole blood (12q24). Thus through a meta-analysis of GWAS enrolling African Americans, we have identified 5 novel regions associated with platelet count of which 3 were replicated in other ethnic groups. In addition, we also found one region associated with platelet aggregation that may play a potential role in atherothrombosis.
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Affiliation(s)
- Rehan Qayyum
- GeneSTAR Research Program, Division of General
Internal Medicine, Johns Hopkins School of Medicine, Baltimore, Maryland, United
States of America
| | - Beverly M. Snively
- Department of Biostatistical Sciences, Wake
Forest School of Medicine, Winston-Salem, North Carolina, United States of
America
| | - Elad Ziv
- Department of Medicine, University of
California San Francisco, San Francisco, California, United States of
America
| | - Michael A. Nalls
- Laboratory of Neurogenetics, National
Institute on Aging, National Institutes of Health, Bethesda, Maryland, United
States of America
| | - Yongmei Liu
- Department of Epidemiology and Prevention,
Division of Public Health Sciences, Wake Forest University School of Medicine,
Winston-Salem, North Carolina, United States of America
| | - Weihong Tang
- Division of Epidemiology and Community Health,
University of Minnesota School of Public Health, Minneapolis, Minnesota, United
States of America
| | - Lisa R. Yanek
- GeneSTAR Research Program, Division of General
Internal Medicine, Johns Hopkins School of Medicine, Baltimore, Maryland, United
States of America
| | - Leslie Lange
- Department of Genetics, School of Medicine,
The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina,
United States of America
| | - Michele K. Evans
- Health Disparities Research Section, Clinical
Research Branch, National Institute on Aging, National Institutes of Health,
Baltimore, Maryland, United States of America
| | - Santhi Ganesh
- Division of Cardiology, University of Michigan
Health System, Ann Arbor, Michigan, United States of America
| | - Melissa A. Austin
- Department of Epidemiology, University of
Washington, Seattle, Washington, United States of America
- Division of Public Health Sciences, Fred
Hutchinson Cancer Research Center, Seattle, Washington, United States of
America
| | | | - Diane M. Becker
- GeneSTAR Research Program, Division of General
Internal Medicine, Johns Hopkins School of Medicine, Baltimore, Maryland, United
States of America
| | - Alan B. Zonderman
- Laboratory of Personality and Cognition,
National Institute on Aging, National Institutes of Health, Baltimore, Maryland,
United States of America
| | - Andrew B. Singleton
- Laboratory of Neurogenetics, National
Institute on Aging, National Institutes of Health, Bethesda, Maryland, United
States of America
| | - Tamara B. Harris
- Laboratory for Epidemiology, Demography, and
Biometry, National Institute on Aging, National Institutes of Health, Baltimore,
Maryland, United States of America
| | - Emile R. Mohler
- Department of Medicine, University of
Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States of
America
| | - Benjamin A. Logsdon
- Program in Biostatistics and Biomathematics,
Division of Public Health Sciences, Fred Hutchinson Cancer Research Center,
Seattle, Washington, United States of America
| | - Charles Kooperberg
- Program in Biostatistics and Biomathematics,
Division of Public Health Sciences, Fred Hutchinson Cancer Research Center,
Seattle, Washington, United States of America
| | - Aaron R. Folsom
- Division of Epidemiology and Community Health,
University of Minnesota School of Public Health, Minneapolis, Minnesota, United
States of America
| | - James G. Wilson
- Department of Medicine, University of
Mississippi Medical Center, Jackson, Mississippi, United States of
America
| | - Lewis C. Becker
- GeneSTAR Research Program, Division of General
Internal Medicine, Johns Hopkins School of Medicine, Baltimore, Maryland, United
States of America
| | - Alexander P. Reiner
- Department of Epidemiology, University of
Washington, Seattle, Washington, United States of America
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Abstract
This chapter summarizes current ideas about the intracellular signaling that drives platelet responses to vascular injury. After a brief overview of platelet activation intended to place the signaling pathways into context, the first section considers the early events of platelet activation leading up to integrin activation and platelet aggregation. The focus is on the G protein-mediated events utilized by agonists such as thrombin and ADP, and the tyrosine kinase-based signaling triggered by collagen. The second section considers the events that occur after integrin engagement, some of which are dependent on close physical contact between platelets. A third section addresses the regulatory events that help to avoid unprovoked or excessive platelet activation, after which the final section briefly considers individual variations in platelet reactivity and the role of platelet signaling in the innate immune response and embryonic development.
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Affiliation(s)
- Timothy J Stalker
- Departments of Medicine and Pharmacology, University of Pennsylvania, Philadelphia, PA, USA
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58
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de Gaetano G, Santimone I, Gianfagna F, Iacoviello L, Cerletti C. Variability of platelet indices and function: acquired and genetic factors. Handb Exp Pharmacol 2012:395-434. [PMID: 22918740 DOI: 10.1007/978-3-642-29423-5_16] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Each individual has an inherent variable risk of bleeding linked to genetic or acquired abnormal platelet number or platelet dysfunction. In contrast, it is less obvious that the variability of platelet phenotypes (number, mean platelet volume, function) may contribute to the variable individual risk of thrombosis. Interindividual variability of platelet indices or function may be either due to acquired factors, such as age, sex, metabolic variables, smoke, dietary habits, and ongoing inflammation, or due to genetic factors. Acquired variables explain a small portion of the heterogeneity of platelet parameters. Genetic factors, instead, appear to play a major role, although a consistent portion of such a genetic variance has not yet been attributed to any specific genetic factor, possibly due to the high number of DNA loci potentially involved and to the limited effect size of each individual SNP. A portion of variance remains thus unexplained, also due to variability of test performance. A major contradiction in present platelet knowledge is, indeed, the difficulty to reconcile the universally accepted importance of platelet indices or function and the lack of reliable platelet parameters in cardiovascular risk prediction models. Trials on antiplatelet drugs were generally designed to select a homogeneous sample, whose results could be applied to an "average subject," tending to exclude the deviation/extreme values. As the current indications for antiplatelet treatment in primary or secondary prevention of ischemic vascular disease still derive from the results of such clinical trials where platelet function and its variability was not investigated, we cannot at present rely upon any current platelet test to either initiate, or monitor, or modify or stop treatment with any antiplatelet drug. Evidence is, however, increasing that traditional platelet aggregometry and other more recently developed platelet function assays could be useful to optimize antiplatelet therapy and to predict major adverse cardiac events.The observation of interindividual differences in platelet response to antiplatelet drugs has enlarged the spectrum and the possible clinical relevance of the variability of platelet indices or function. The development of "personalized medicine" will benefit from the concepts discussed in this chapter.
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Affiliation(s)
- Giovanni de Gaetano
- Research Laboratories, Fondazione di Ricerca e Cura "Giovanni Paolo II", Università Cattolica, Largo Gemelli, 1, 86100, Campobasso, Italy.
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Vohnout B, Gianfagna F, Lorenzet R, Cerletti C, de Gaetano G, Donati MB, Iacoviello L. Genetic regulation of inflammation-mediated activation of haemostasis: family-based approaches in population studies. Nutr Metab Cardiovasc Dis 2011; 21:857-861. [PMID: 20692137 DOI: 10.1016/j.numecd.2010.03.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2009] [Revised: 02/02/2010] [Accepted: 03/08/2010] [Indexed: 11/25/2022]
Abstract
Blood coagulation and inflammation play a key role in atherosclerosis and thrombosis. Candidate gene and genome wide association studies have identified potential specific genes that might have a causal role in these pathogenic processes. The analysis of quantitative traits is more powerful as they are closer to direct gene action than disease phenotypes. Thus linkage-based studies on extended families might be useful both to estimate the heritability and to map the genetic loci responsible for the regulation of the trait. Family-based studies may estimate high heritability for thrombosis and quantitative traits regarding both platelet aggregation and blood coagulation. Some specific loci relevant to thrombosis have been identified, with some of them showing a direct pleiotropic effect on the risk of thrombosis. Haemostasis factors can be activated by inflammatory stimuli. Fibrinogen level is genetically correlated with C-reactive protein levels with a link for both traits on chromosomes 12 and 21. Genes related to prostanoid biosynthesis, involved both in inflammation and thrombosis, show high heritability levels in both enzyme expression and prostanoid production. Considering that few large family-based linkage studies have as yet been performed on haemostasis and inflammation-related traits, additional studies are highly needed. We are performing a family-based linkage study on large pedigrees (750 subjects from 23 families with juvenile myocardial infarction and 31 control families), to identify genes responsible for quantitative traits involved in the pathway progressively going from inflammation to haemostasis, cell activation, thrombus formation and cardiovascular events.
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Affiliation(s)
- B Vohnout
- Laboratory of Genetic and Environmental Epidemiology, Italy
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60
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Identification of a specific intronic PEAR1 gene variant associated with greater platelet aggregability and protein expression. Blood 2011; 118:3367-75. [PMID: 21791418 DOI: 10.1182/blood-2010-11-320788] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Genetic variation is thought to contribute to variability in platelet function; however, the specific variants and mechanisms that contribute to altered platelet function are poorly defined. With the use of a combination of fine mapping and sequencing of the platelet endothelial aggregation receptor 1 (PEAR1) gene we identified a common variant (rs12041331) in intron 1 that accounts for ≤ 15% of total phenotypic variation in platelet function. Association findings were robust in 1241 persons of European ancestry (P = 2.22 × 10⁻⁸) and were replicated down to the variant and nucleotide level in 835 persons of African ancestry (P = 2.31 × 10⁻²⁷) and in an independent sample of 2755 persons of European descent (P = 1.64 × 10⁻⁵). Sequencing confirmed that variation at rs12041331 accounted most strongly (P = 2.07 × 10⁻⁶) for the relation between the PEAR1 gene and platelet function phenotype. A dose-response relation between the number of G alleles at rs12041331 and expression of PEAR1 protein in human platelets was confirmed by Western blotting and ELISA. Similarly, the G allele was associated with greater protein expression in a luciferase reporter assay. These experiments identify the precise genetic variant in PEAR1 associated with altered platelet function and provide a plausible biologic mechanism to explain the association between variation in the PEAR1 gene and platelet function phenotype.
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61
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Zufferey A, Reny JL, Combescure C, de Moerloose P, Sanchez JC, Fontana P. Platelet reactivity is a stable and global phenomenon in aspirin-treated cardiovascular patients. Thromb Haemost 2011; 106:466-74. [PMID: 21725581 DOI: 10.1160/th11-04-0226] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Accepted: 06/13/2011] [Indexed: 12/14/2022]
Abstract
In healthy subjects, platelet hyperreactivity is a global phenomenon--as opposed to agonist-specific--and epinephrine-induced platelet aggregation (EPA) is a reliable marker of this phenotype. Few data are available on platelet reactivity and the relationship between EPA and aggregation induced by other agonists in cardiovascular patients. It was the objective of this study to characterise platelet reactivity in stable cardiovascular patients treated with aspirin and to derive a composite index integrating several aggregation pathways, suitable for selecting patients with extreme phenotypes for further proteomics analysis. Platelet reactivity to agonists was assessed in 110 patients twice, two weeks apart. Factorial analysis was used to determine whether the results obtained with the different agonists could be summarised in a single composite index. EPA correlated with the aggregation values obtained with each of the other agonists, with correlation coefficients of 0.44 to 0.55 (p < 0.001). We constructed a composite "platelet reactivity" index that included 60% of the information provided by each agonist. The results obtained at the first patient visit were consistent with those obtained at the second visit (r = 0.78, p<0.01). No clinical or biological parameters correlated with the composite index. The extreme phenotypes of six selected subjects were confirmed 12 months after the second visit. In conclusion, platelet reactivity in aspirin-treated cardiovascular patients is a global phenomenon that can be summarised by a composite index based on the aggregation responses to various agonists and integrating several activation pathways. This index is not dependent on clinical or biological variables, suggesting that genetic factors regulate platelet reactivity in these patients.
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Affiliation(s)
- Anne Zufferey
- Division of Angiology and Haemostasis, Geneva University Hospital and Faculty of Medicine, Switzerland
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62
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Johnson AD. The genetics of common variation affecting platelet development, function and pharmaceutical targeting. J Thromb Haemost 2011; 9 Suppl 1:246-57. [PMID: 21781261 PMCID: PMC3151008 DOI: 10.1111/j.1538-7836.2011.04359.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Common variant effects on human platelet function and response to anti-platelet treatment have traditionally been studied using candidate gene approaches involving a limited number of variants and genes. These studies have often been undertaken in clinically defined cohorts. More recently, studies have applied genome-wide scans in larger population samples than prior candidate studies, in some cases scanning relatively healthy individuals. These studies demonstrate synergy with some prior candidate gene findings (e.g., GP6, ADRA2A) but also uncover novel loci involved in platelet function. Here, I summarise findings on common genetic variation influencing platelet development, function and therapeutics. Taken together, candidate gene and genome-wide studies begin to account for common variation in platelet function and provide information that may ultimately be useful in pharmacogenetic applications in the clinic. More than 50 loci have been identified with consistent associations with platelet phenotypes in ≥ 2 populations. Several variants are under further study in clinical trials relating to anti-platelet therapies. In order to have useful clinical applications, variants must have large effects on a modifiable outcome. Regardless of clinical applications, studies of common genetic influences, even of small effect, offer additional insights into platelet biology including the importance of intracellular signalling and novel receptors. Understanding of common platelet-related genetics remains behind parallel fields (e.g., lipids, blood pressure) due to challenges in phenotype ascertainment. Further work is necessary to discover and characterise loci for platelet function, and to assess whether these loci contribute to disease aetiologies or response to therapeutics.
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Affiliation(s)
- A D Johnson
- National Heart, Lung and Blood Institute's The Framingham Heart Study, Framingham, MA 01702, USA.
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63
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Mathias RA, Sergeant S, Ruczinski I, Torgerson DG, Hugenschmidt CE, Kubala M, Vaidya D, Suktitipat B, Ziegler JT, Ivester P, Case D, Yanek LR, Freedman BI, Rudock ME, Barnes KC, Langefeld CD, Becker LC, Bowden DW, Becker DM, Chilton FH. The impact of FADS genetic variants on ω6 polyunsaturated fatty acid metabolism in African Americans. BMC Genet 2011; 12:50. [PMID: 21599946 PMCID: PMC3118962 DOI: 10.1186/1471-2156-12-50] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2010] [Accepted: 05/20/2011] [Indexed: 02/05/2023] Open
Abstract
Background Arachidonic acid (AA) is a long-chain omega-6 polyunsaturated fatty acid (PUFA) synthesized from the precursor dihomo-gamma-linolenic acid (DGLA) that plays a vital role in immunity and inflammation. Variants in the Fatty Acid Desaturase (FADS) family of genes on chromosome 11q have been shown to play a role in PUFA metabolism in populations of European and Asian ancestry; no work has been done in populations of African ancestry to date. Results In this study, we report that African Americans have significantly higher circulating levels of plasma AA (p = 1.35 × 10-48) and lower DGLA levels (p = 9.80 × 10-11) than European Americans. Tests for association in N = 329 individuals across 80 nucleotide polymorphisms (SNPs) in the Fatty Acid Desaturase (FADS) locus revealed significant association with AA, DGLA and the AA/DGLA ratio, a measure of enzymatic efficiency, in both racial groups (peak signal p = 2.85 × 10-16 in African Americans, 2.68 × 10-23 in European Americans). Ancestry-related differences were observed at an upstream marker previously associated with AA levels (rs174537), wherein, 79-82% of African Americans carry two copies of the G allele compared to only 42-45% of European Americans. Importantly, the allelic effect of the G allele, which is associated with enhanced conversion of DGLA to AA, on enzymatic efficiency was similar in both groups. Conclusions We conclude that the impact of FADS genetic variants on PUFA metabolism, specifically AA levels, is likely more pronounced in African Americans due to the larger proportion of individuals carrying the genotype associated with increased FADS1 enzymatic conversion of DGLA to AA.
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Affiliation(s)
- Rasika A Mathias
- Division of General Internal Medicine, Department of Medicine, The GeneSTAR Research Program, The Johns Hopkins University, Baltimore, MD 21224, USA.
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64
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Kameda S, Sakata T, Kokubo Y, Mitsuguro M, Okamoto A, Sano M, Miyata T. Association of platelet aggregation with lipid levels in the Japanese population: the Suita study. J Atheroscler Thromb 2011; 18:560-7. [PMID: 21427509 DOI: 10.5551/jat.6288] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
AIM Platelets play a pivotal role in atherothrombotic diseases. Platelet aggregability induced by agonists has great interindividual variability; however, the factors influencing platelet aggregability variation have not been characterized in Asia. METHODS To examine the confounding factors influencing platelet counts and responsiveness to agonists, we measured the platelet counts and platelet aggregability induced by 1.7 µM adenosine diphosphate (ADP) or 1.7 µg/mL collagen using a light transmittance aggregometer in the Japanese general population without medication or cardiovascular disease (387 men and 550 women) in the Suita Study. RESULTS Platelet counts were negatively correlated with age in both men and women (Spearman's rank correlation coefficient: r(s)=-0.230 and -0.227; p< 0.01, respectively). In women, platelet counts were correlated negatively with the high-density lipoprotein (HDL) cholesterol level and positively with the low-density lipoprotein (LDL) cholesterol/HDL cholesterol (L/H) ratio (r(s)=-0.135 and 0.119; p< 0.01, respectively). In women, platelet aggregabilities by ADP and collagen were correlated with age (r(s)=0.118 and 0.143; p< 0.01, respectively), and collagen-induced platelet aggregability was correlated with the LDL cholesterol level, the L/H ratio, and the non-HDL cholesterol level (r(s)=0.167, 0.172, and 0.185; p< 0.01, respectively). Even after adjustment for age, systolic blood pressure, body mass index, and current smoking and drinking, the association of platelet counts with the L/H ratio in women and associations of collagen-induced platelet aggregability with the L/H ratio and the non-HDL cholesterol level remained. CONCLUSION Examination of platelet counts and platelet aggregability induced by ADP and collagen revealed gender, age and lipid levels as factors influencing inter-individual variability.
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Affiliation(s)
- Sachika Kameda
- Laboratory of Clinical Chemistry, National Cerebral and Cardiovascular Center, Fujishiro-dai, Suita, Osaka, Japan.
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Abstract
MicroRNAs (miRNAs) regulate cell physiology by altering protein expression, but the biology of platelet miRNAs is largely unexplored. We tested whether platelet miRNA levels were associated with platelet reactivity by genome-wide profiling using platelet RNA from 19 healthy subjects. We found that human platelets express 284 miRNAs. Unsupervised hierarchical clustering of miRNA profiles resulted in 2 groups of subjects that appeared to cluster by platelet aggregation phenotypes. Seventy-four miRNAs were differentially expressed (DE) between subjects grouped according to platelet aggregation to epinephrine, a subset of which predicted the platelet reactivity response. Using whole genome mRNA expression data on these same subjects, we computationally generated a high-priority list of miRNA-mRNA pairs in which the DE platelet miRNAs had binding sites in 3'-untranslated regions of DE mRNAs, and the levels were negatively correlated. Three miRNA-mRNA pairs (miR-200b:PRKAR2B, miR-495:KLHL5, and miR-107:CLOCK) were selected from this list, and all 3 miRNAs knocked down protein expression from the target mRNA. Reduced activation from platelets lacking PRKAR2B supported these findings. In summary, (1) platelet miRNAs are able to repress expression of platelet proteins, (2) miRNA profiles are associated with and may predict platelet reactivity, and (3) bioinformatic approaches can successfully identify functional miRNAs in platelets.
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Williams MS, Weiss EJ, Sabatine MS, Simon DI, Bahou WF, Becker LC, Parise LV, Dauerman HL, French PA, Smyth SS, Becker RC. Genetic regulation of platelet receptor expression and function: application in clinical practice and drug development. Arterioscler Thromb Vasc Biol 2010; 30:2372-84. [PMID: 21084706 DOI: 10.1161/atvbaha.110.218131] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Understanding genetic contributions to platelet function could have profound clinical ramifications for personalizing platelet-directed pharmacotherapy, by providing insight into the risks and possible benefits associated with specific genotypes. This article represents an integrated summary of presentations related to genetic regulation of platelet receptor expression and function given at the Fifth Annual Platelet Colloquium in January 2010. It is supplemented with additional highlights from the literature covering (1) approaches to determining and evidence for the associations of genetic variants with platelet hypo- and hyperresponsive phenotypes, (2) the ramifications of these polymorphisms with regard to clinical responses to antiplatelet therapies, and (3) the role of platelet function/genetic testing in guiding antiplatelet therapy.
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Affiliation(s)
- Marlene S Williams
- Division of Cardiology, Department of Medicine, Johns Hopkins University, Baltimore, Md 21224, USA.
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The G protein β3 subunit C825T polymorphism is associated with microalbuminuria in hypertensive women and cardiovascular disease in hypertensive men. Am J Hypertens 2010; 23:1114-20. [PMID: 20577224 DOI: 10.1038/ajh.2010.131] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND The aim of the study was to examine the association between the G protein β3 subunit C825T polymorphism, associated with cardiovascular risk factors like hypertension (HT) and obesity and microalbuminuria (MA), reflecting the endothelial dysfunction in the atherosclerotic process. Second, we wanted to examine the association between the polymorphism and cardiovascular disease (CVD). METHODS In the large population-based, cross-sectional Nord-Trøndelag Health Study, HUNT 1995-1997, a total of 5,755 treated hypertensive individuals attended the MA substudy. A randomly selected sample of 1,000 of these was genotyped. A total of 402 men and 540 women were included in the final analyses. MA was measured as albumin/creatinine ratio (ACR) in three urine samples. Logistic regression was used to calculate odds ratios (ORs) for the association between MA or CVD and the genotype. RESULTS The study demonstrated a positive association between the TT genotype and MA in women (OR 3.2, 95% confidence interval (CI): 1.1-8.7, P = 0.03), but not in men. The association became stronger with increasing number of positive urine samples and with increasing cutoff value in women with TT genotype compared to the CC genotype. Additionally, there was a positive association between TT genotype and CVD in men and postmenopausal women without hormone therapy. CONCLUSIONS Increased MA in TT homozygous women might be explained by other mechanisms of albuminuria or inflammation than the atherosclerotic process. We postulate that the association between CVD and the genotype are mediated through mechanisms other than the classical risk factors and endothelial dysfunction, reflected by MA, which have to be further investigated.
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Abstract
Genetic and environmental factors contribute to a substantial variation in platelet function seen among normal persons. Candidate gene association studies represent a valiant effort to define the genetic component in an era where genetic tools were limited, but the single nucleotide polymorphisms identified in those studies need to be validated by more objective, comprehensive approaches, such as genome-wide association studies (GWASs) of quantitative functional traits in much larger cohorts of more carefully selected normal subjects. During the past year, platelet count and mean platelet volume, which indirectly affect platelet function, were the subjects of GWAS. The majority of the GWAS signals were located to noncoding regions, a consistent outcome of all GWAS to date, suggesting a major role for mechanisms that alter phenotype at the level of transcription or posttranscriptional modifications. Of 15 quantitative trait loci associated with mean platelet volume and platelet count, one located at 12q24 is also a risk locus for coronary artery disease. In most cases, the effect sizes of individual quantitative trait loci are admittedly small, but the results of these studies have led to new insight into regulators of hematopoiesis and megakaryopoiesis that would otherwise be unapparent and difficult to define.
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Johnson AD, Yanek LR, Chen MH, Faraday N, Larson MG, Tofler G, Lin SJ, Kraja AT, Province MA, Yang Q, Becker DM, O'Donnell CJ, Becker LC. Genome-wide meta-analyses identifies seven loci associated with platelet aggregation in response to agonists. Nat Genet 2010; 42:608-13. [PMID: 20526338 PMCID: PMC3057573 DOI: 10.1038/ng.604] [Citation(s) in RCA: 206] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2009] [Accepted: 05/12/2010] [Indexed: 12/26/2022]
Abstract
Platelet function mediates both beneficial and harmful effects on human health, but few genes are known to contribute to variability in this process. We tested association of 2.5 million SNPs with platelet aggregation responses to three agonists (ADP, epinephrine and collagen) in two cohorts of European ancestry (N
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Affiliation(s)
- Andrew D Johnson
- National Heart, Lung, and Blood Institute's The Framingham Heart Study, Framingham, Massachusetts, USA.
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Mathias RA, Kim Y, Sung H, Yanek LR, Mantese VJ, Hererra-Galeano JE, Ruczinski I, Wilson AF, Faraday N, Becker LC, Becker DM. A combined genome-wide linkage and association approach to find susceptibility loci for platelet function phenotypes in European American and African American families with coronary artery disease. BMC Med Genomics 2010; 3:22. [PMID: 20529293 PMCID: PMC2890666 DOI: 10.1186/1755-8794-3-22] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2009] [Accepted: 06/07/2010] [Indexed: 01/27/2023] Open
Abstract
Background The inability of aspirin (ASA) to adequately suppress platelet aggregation is associated with future risk of coronary artery disease (CAD). Heritability studies of agonist-induced platelet function phenotypes suggest that genetic variation may be responsible for ASA responsiveness. In this study, we leverage independent information from genome-wide linkage and association data to determine loci controlling platelet phenotypes before and after treatment with ASA. Methods Clinical data on 37 agonist-induced platelet function phenotypes were evaluated before and after a 2-week trial of ASA (81 mg/day) in 1231 European American and 846 African American healthy subjects with a family history of premature CAD. Principal component analysis was performed to minimize the number of independent factors underlying the covariance of these various phenotypes. Multi-point sib-pair based linkage analysis was performed using a microsatellite marker set, and single-SNP association tests were performed using markers from the Illumina 1 M genotyping chip from deCODE Genetics, Inc. All analyses were performed separately within each ethnic group. Results Several genomic regions appear to be linked to ASA response factors: a 10 cM region in African Americans on chromosome 5q11.2 had several STRs with suggestive (p-value < 7 × 10-4) and significant (p-value < 2 × 10-5) linkage to post aspirin platelet response to ADP, and ten additional factors had suggestive evidence for linkage (p-value < 7 × 10-4) to thirteen genomic regions. All but one of these factors were aspirin response variables. While the strength of genome-wide SNP association signals for factors showing evidence for linkage is limited, especially at the strict thresholds of genome-wide criteria (N = 9 SNPs for 11 factors), more signals were considered significant when the association signal was weighted by evidence for linkage (N = 30 SNPs). Conclusions Our study supports the hypothesis that platelet phenotypes in response to ASA likely have genetic control and the combined approach of linkage and association offers an alternative approach to prioritizing regions of interest for subsequent follow-up.
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Affiliation(s)
- Rasika A Mathias
- Genometrics Section, Inherited Disease Research Branch, National Human Genome Research Institute, National Institutes of Health, Baltimore, MD, USA.
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Maree AO, Vangjeli C, Jneid H, Ryan J, Cox D, Cannon CP, Shields DC, Fitzgerald DJ. G-protein beta3 subunit polymorphism and bleeding in the orbofiban in patients with unstable coronary syndromes-thrombolysis in myocardial infarction 16 trial. J Thromb Haemost 2010; 8:934-41. [PMID: 20096003 DOI: 10.1111/j.1538-7836.2010.03775.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
SUMMARY BACKGROUND Variability in platelet response to antiplatelet drugs is heritable. A common single base substitution (825C>T) in the G-protein beta polypeptide 3 (GNB3) gene leads to alternative splicing (41-amino-acid deletion) of the human G-protein beta3 (Gbeta3) subunit. This truncated protein carried by GNB3 T allele carriers is linked to coronary artery disease and implicated as a genetic marker of drug response. Large studies of Caucasians associate T allele carriage with lower platelet reactivity. OBJECTIVES To evaluate whether the GNB3 genotype would predispose to bleeding in patients treated with a GPIIb/IIIa receptor antagonist. METHODS GNB3 genotype distribution was determined in DNA samples from patients in the orbofiban in patients with unstable coronary syndromes-thrombolysis in myocardial infarction (OPUS-TIMI) 16 genetic sub-study. Impact of genotype on the bleeding endpoint and the composite primary endpoint of death, myocardial infarction (MI), re-hospitalization for ischemia and urgent revascularization was estimated in the treatment and placebo arm. RESULTS Out of 887 patients, 45.1% carried the GNB3 CC genotype, 44.5% CT and 10.4% TT. Interaction between T allele carriership and treatment for bleeding was significant (P = 0.008). This reflects the fact that GNB3 non-T carriers treated with orbofiban had no bleeding effect compared with placebo (RR = 0.92, 95% CI 0.55-1.55) whereas T carriers did (RR = 2.62, 95% CI 1.58-4.35, P < 0.001). Interaction between T allele carriership and treatment was not significant for the primary endpoint (P = 0.18) or MI (P = 0.69). CONCLUSION The GNB3 T allele significantly increased bleeding in patients treated with the platelet antagonist orbofiban. Our findings suggest that risk of bleeding associated with an antiplatelet agent is heritable and may be dissociated from risk of thrombosis.
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Affiliation(s)
- A O Maree
- Department of Clinical Pharmacology, Royal College of Surgeons, Dublin, Ireland.
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73
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Kondkar AA, Bray MS, Leal SM, Nagalla S, Liu DJ, Jin Y, Dong JF, Ren Q, Whiteheart SW, Shaw C, Bray PF. VAMP8/endobrevin is overexpressed in hyperreactive human platelets: suggested role for platelet microRNA. J Thromb Haemost 2010; 8:369-78. [PMID: 19943878 PMCID: PMC3312605 DOI: 10.1111/j.1538-7836.2009.03700.x] [Citation(s) in RCA: 149] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Variation in platelet reactivity contributes to disorders of hemostasis and thrombosis, but the molecular mechanisms are not well understood. OBJECTIVES To discover associations between interindividual platelet variability and the responsible platelet genes, and to begin to define the molecular mechanisms altering platelet gene expression. SUBJECTS/METHODS Two hundred and eighty-eight healthy subjects were phenotyped for platelet responsiveness. Platelet RNA from subjects demonstrating hyperreactivity (n=18) and hyporeactivity (n=11) was used to screen the human transcriptome. RESULTS Distinctly different mRNA profiles were observed between subjects with differing platelet reactivity. Increased levels of mRNA for VAMP8/endobrevin, a critical v-SNARE involved in platelet granule secretion, were associated with platelet hyperreactivity (Q=0.0275). Validation studies of microarray results showed 4.8-fold higher mean VAMP8 mRNA levels in hyperreactive than hyporeactive platelets (P=0.0023). VAMP8 protein levels varied 13-fold among platelets from these normal subjects, and were 2.5-fold higher in hyperreactive platelets (P=0.05). Among our cohort of 288 subjects, a VAMP8 single-nucleotide polymorphism (rs1010) was associated with platelet reactivity in an age-dependent manner (P<0.003). MicroRNA-96 was predicted to bind to the 3'-untranslated regionof VAMP8 mRNA and was detected in platelets. Overexpression of microRNA-96 in VAMP8-expressing cell lines caused a dose-dependent decrease in VAMP8 protein and mRNA, suggesting a role in VAMP8 mRNA degradation. CONCLUSIONS These findings support a role for VAMP8/endobrevin in the heterogeneity of platelet reactivity, and suggest a role for microRNA-96 in the regulation of VAMP8 expression.
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Affiliation(s)
- A A Kondkar
- Thomas Jefferson University, The Cardeza Foundation for Hematologic Research and the Department of Medicine, Jefferson Medical College, Philadelphia, PA 19107, USA
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Vila L, Martinez-Perez A, Camacho M, Buil A, Alcolea S, Pujol-Moix N, Soler M, Antón R, Souto JC, Fontcuberta J, Soria JM. Heritability of thromboxane A2 and prostaglandin E2 biosynthetic machinery in a Spanish population. Arterioscler Thromb Vasc Biol 2009; 30:128-34. [PMID: 19850905 DOI: 10.1161/atvbaha.109.193219] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Prostanoids play a critical role in clinical areas such as inflammation, thrombosis, immune response, and cancer. Although some studies suggest that there are genes that determine variability of some prostanoid-related phenotypes, the genetic influence on these traits has not been evaluated. METHODS AND RESULTS The relative contributions of genetic and environmental influences to the prostanoid biosynthetic pathway-related phenotypes, cyclooxygenase isoenzymes, microsomal-PGE-synthase-1 and TxA-synthase expression, and thromboxane-A(2) and prostaglandin-E(2) production by stimulated whole blood, were assessed in a sample of 308 individuals in 15 extended families. The effects of measured covariates (such as sex, age, and smoking), genes, and environmental variables shared by members of a household were quantified. Heritabilities ranging from 0.406 to 0.634 for enzyme expression and from 0.283 to 0. 751 for prostanoid production were found. CONCLUSIONS These results demonstrate clearly the importance of genetic factors in determining variation in phenotypes that are components of the prostanoid biosynthetic pathways. The presence of such strong genetic effects suggest that it will be possible to localize previously unknown genes that influence quantitative variation in these phenotypes, some of which affect multiple aspects of cell biology, with important clinical implications.
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Affiliation(s)
- Luis Vila
- H.S. Creu i S. Pau, S. Antonio M Claret 167, 08025-Barcelona, Spain.
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A functional genomics approach reveals novel quantitative trait loci associated with platelet signaling pathways. Blood 2009; 114:1405-16. [PMID: 19429868 DOI: 10.1182/blood-2009-02-202614] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Platelet response to activation varies widely between individuals but shows interindividual consistency and strong heritability. The genetic basis of this variation has not been properly explored. We therefore systematically measured the effect on function of sequence variation in 97 candidate genes in the collagen and adenosine-diphosphate (ADP) signaling pathways. Resequencing of the genes in 48 European DNA samples nearly doubled the number of known single nucleotide polymorphisms (SNPs) and informed the selection of 1327 SNPs for genotyping in 500 healthy Northern European subjects with known platelet responses to collagen-related peptide (CRP-XL) and ADP. This identified 17 novel associations with platelet function (P < .005) accounting for approximately 46% of the variation in response. Further investigations with platelets of known genotype explored the mechanisms behind some of the associations. SNPs in PEAR1 associated with increased platelet response to CRP-XL and increased PEAR1 protein expression after platelet degranulation. The minor allele of a 3' untranslated region (UTR) SNP (rs2769668) in VAV3 was associated with higher protein expression (P = .03) and increased P-selectin exposure after ADP activation (P = .004). Furthermore the minor allele of the intronic SNP rs17786144 in ITPR1 modified Ca(2+) levels after activation with ADP (P < .004). These data provide novel insights into key hubs within platelet signaling networks.
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Hayward CPM, Pai M, Liu Y, Moffat KA, Seecharan J, Webert KE, Cook RJ, Heddle NM. Diagnostic utility of light transmission platelet aggregometry: results from a prospective study of individuals referred for bleeding disorder assessments. J Thromb Haemost 2009; 7:676-84. [PMID: 19143930 DOI: 10.1111/j.1538-7836.2009.03273.x] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
BACKGROUND Light transmission aggregometry (LTA) is commonly performed to assess individuals for bleeding disorders. OBJECTIVES The goal was to evaluate the incidence and spectrum of platelet function abnormalities in a prospective cohort of individuals referred for bleeding disorder assessments after exclusion of thrombocytopenia and von Willebrand disease. PATIENTS/METHODS Subjects were healthy controls and patients from a prospective cohort of individuals referred for bleeding disorder assessments after exclusion of thrombocytopenia and von Willebrand disease. LTA was performed by standardized methods using platelet-rich plasma adjusted to 250x10(9) platelets L(-1). Maximal aggregation data were analyzed to determine the likelihood of detecting a platelet function disorder by LTA, and the sensitivity and specificity of LTA for platelet disorders. RESULTS The incidence of false positive LTA among subjects excluded of having bleeding disorders was similar to healthy controls. Abnormal LTA was more common in subjects with bleeding disorders and the likelihood of a bleeding disorder was significantly increased (odds ratio 32) when maximal aggregation was reduced with two or more agonists. Receiver operator curve analyses indicated that LTA had high specificity and moderate sensitivity for detecting inherited defects in platelet function and that the LTA agonists 1.25 microg mL(-1) collagen, 6 microM epinephrine, 1.6 mM arachidonic acid and 1.0 microM thromboxane analogue U44619 detected most inherited disorders with abnormal LTA. CONCLUSIONS LTA is valuable for detecting platelet function abnormalities among individuals referred for bleeding problems, particularly when the test indicates abnormal responses to multiple agonists.
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Affiliation(s)
- C P M Hayward
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada.
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Rivera J, Lozano ML, Navarro-Núñez L, Vicente V. Platelet receptors and signaling in the dynamics of thrombus formation. Haematologica 2009; 94:700-11. [PMID: 19286885 DOI: 10.3324/haematol.2008.003178] [Citation(s) in RCA: 257] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Hemostasis and pathological thrombus formation are dynamic processes that require a co-ordinated series of events involving platelet membrane receptors, bidirectional intracellular signals, and release of platelet proteins and inflammatory substances. This review aims to summarize current knowledge in the key steps in the dynamics of thrombus formation, with special emphasis on the crucial participation of platelet receptors and signaling in this process. Initial tethering and firm adhesion of platelets to the exposed subendothelium is mediated by glycoprotein (GP) Ib/IX/V complex and collagen receptors, GP VI and alpha(2)beta(1) integrin, in the platelet surface, and by VWF and fibrillar collagen in the vascular site. Interactions between these elements are largely influenced by flow and trigger signaling events that reinforce adhesion and promote platelet activation. Thereafter, soluble agonists, ADP, thrombin, TxA(2), produced/released at the site of vascular injury act in autocrine and paracrine mode to amplify platelet activation and to recruit circulating platelets to the developing thrombus. Specific interactions of these agonists with their G-protein coupled receptors generate inside-out signaling leading to conformational activation of integrins, in particular alpha(IIb)beta(3), increasing their ligand affinity. Binding of alpha(IIb)beta(3) to its ligands, mainly fibrinogen, supports processes such as clot retraction and platelet aggregation. Stabilization of thrombi is supported by the late wave of signaling events promoted by close contact between aggregated platelets. The best known contact-dependent signaling is outside-in signaling through alphaIb beta(3), but new ones are being clarified such as those mediated by interaction of Eph receptors with ephrins, or by Sema 4D and Gas-6 binding to their receptors. Finally, newly identified mechanisms appear to control thrombus growth, including back-shifting of activated integrins and actuation of compensatory molecules such as ESAM or PECAM-1. The expanding knowledge of thrombotic disease is expected to translate into the development of new drugs to help management and prevention of thrombosis.
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Affiliation(s)
- José Rivera
- Centro Regional de Hemodonación, Universidad de Murcia, C/ Ronda de Garay s/n., Murcia, Spain
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Affiliation(s)
- Mark Y Chan
- Duke Clinical Research Institute, Durham, NC 27705, USA
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Peace AJ, Tedesco AF, Foley DP, Dicker P, Berndt MC, Kenny D. Dual antiplatelet therapy unmasks distinct platelet reactivity in patients with coronary artery disease. J Thromb Haemost 2008; 6:2027-34. [PMID: 18823340 DOI: 10.1111/j.1538-7836.2008.03157.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
BACKGROUND Platelet-induced thrombosis is a major risk factor for recurrent ischemic events, although platelet function in patients with cardiovascular disease taking aspirin and clopidogrel is very poorly characterized. The aim of this study was to assess platelet reactivity in patients with cardiovascular disease taking aspirin and clopidogrel. METHODS We developed a rapid assay to measure platelet aggregation in response to arachidonic acid, collagen, adenosine diphosphate (ADP), epinephrine and thrombin receptor activating peptide (TRAP) in 80 healthy volunteers. We then recruited 200 consecutive patients from outpatient clinics and the cardiac catheterization laboratory and tested platelet function. Platelet aggregation induced by epinephrine is a marker of global platelet reactivity. We tested platelet function in 146 patients compliant with antiplatelet therapy. Platelet aggregation to epinephrine was divided into quartiles. The platelet response to the other agonists was analysed based on the response to epinephrine. RESULTS Platelet reactivity increased significantly across the quartiles in response to epinephrine in healthy volunteers and patients (P < 0.0001). A significant increase in response across quartiles was seen with all agonists in healthy volunteers (P < 0.001). In contrast, a significant increase in response across quartiles was only seen with ADP in patients (P < 0.0001). Hypertension, smoking and diabetes were significantly associated with increasing platelet reactivity to epinephrine (P < 0.05). CONCLUSION This study shows that platelet response differs between healthy volunteers and patients on dual antiplatelet therapy. In patients with cardiovascular disease, dual antiplatelet therapy unmasks a distinct type of platelet reactivity in response to epinephrine and ADP but not other agonists.
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Affiliation(s)
- A J Peace
- Department of Molecular and Cellular Therapeutics, Royal College of Surgeons in Ireland, Dublin, Ireland.
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Editor’s page: fundamentals in neurocardiology. J Thromb Thrombolysis 2008; 26:74-7. [DOI: 10.1007/s11239-008-0255-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2008] [Accepted: 07/07/2008] [Indexed: 10/21/2022]
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Herrera-Galeano JE, Becker DM, Wilson AF, Yanek LR, Bray P, Vaidya D, Faraday N, Becker LC. A novel variant in the platelet endothelial aggregation receptor-1 gene is associated with increased platelet aggregability. Arterioscler Thromb Vasc Biol 2008; 28:1484-90. [PMID: 18511696 DOI: 10.1161/atvbaha.108.168971] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Platelet endothelial aggregation receptor-1 (PEAR1) is a recently identified platelet transmembrane protein that becomes activated by platelet contact. We looked for novel genetic variants in PEAR1 and studied their association with agonist-induced native platelet aggregation and with the inhibitory effect of aspirin on platelets. METHODS AND RESULTS We genotyped PEAR1 for 10 single nucleotide polymorphisms (SNPs), selected for optimal gene coverage at a density of 4 kb, in 1486 apparently healthy individuals from two generations of families with premature CAD. Subjects had a mean age of 45 years; 62% were white and 38% black. Platelet aggregation to collagen, epinephrine, and ADP was measured in platelet rich plasma, at baseline and after 2 weeks of aspirin (ASA, 81 mg/d), and genotype-phenotype associations were examined separately by ethnicity using multivariable generalized linear models adjusted for covariates. The C allele of SNP rs2768759 [A/C], located in the promoter region of the gene, was common in whites and uncommon in blacks (allele frequency 70.2% versus 17.7%). The C allele was generally associated in both ethnic groups with increased aggregation of native platelets to each agonist. After ASA, the associations were stronger and more consistent and remained significant when post-ASA aggregation was adjusted for baseline aggregation, consistent with a relationship between the C allele and reduced platelet responsiveness to ASA. The PEAR1 SNP explained up to 6.9% of the locus specific genetic variance in blacks and up to 2.5% of the genetic variance in whites after ASA. CONCLUSIONS PEAR1 appears to play an important role in agonist-induced platelet aggregation and in the response to ASA in both whites and blacks.
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Affiliation(s)
- J Enrique Herrera-Galeano
- Departments of Medicine and Anesthesiology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA
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Abstract
Platelet thrombi are central to the development of most vascular ischemic events. There is marked interindividual variation in platelet responsiveness, with some subjects displaying platelet hyperreactivity. An increasing number of reports indicate that there are laboratory measures of platelet function that predict clinical thrombotic events. Some, but not all, measures of platelet function are reproducible. Platelet hyperreactivity can be assessed with multiple stimuli in multiple assays and is more likely to be present in women and in subjects who have elevated fibrinogen levels.
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Affiliation(s)
- Paul F Bray
- Division of Hematology, Cardeza Foundation for Hematologic Research, Jefferson Medical College, Philadelphia, PA 19107, USA.
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