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PLoS One. 2017 May 23;12(5):e0178095. doi: 10.1371/journal.pone.0178095. eCollection 2017.

SNP in human ARHGEF3 promoter is associated with DNase hypersensitivity, transcript level and platelet function, and Arhgef3 KO mice have increased mean platelet volume.

Author information

1
Department of Cell Biology, Yale School of Medicine, New Haven, Connecticut, United States of America.
2
Department of Pathology, Yale School of Medicine, New Haven, Connecticut, United States of America.
3
Department of Haematology, University of Cambridge, Cambridge Biomedical Campus, Cambridge, United Kingdom.
4
Department of Structural and Computational Biology, Baylor College of Medicine, Houston, TX, United States of America.
5
Department of ENT, Addenbrooke's Hospital, Cambridge Biomedical Campus, Cambridge, United Kingdom.
6
Yale Cardiovascular Research Center, Department of Cardiology, Yale University School of Medicine, New Haven, CT, United States of America.
7
Department of Laboratory Medicine, Yale School of Medicine, New Haven, Connecticut, United States of America.
8
Yale Stem Cell Center, Yale School of Medicine, New Haven, Connecticut, United States of America.
9
University of Groningen, University Medical Center Groningen, Department of Cardiology, Groningen, The Netherlands.
10
University of Groningen, University Medical Center Groningen, Department of Genetics, Groningen, The Netherlands.
11
Department of Medicine and the Program in Molecular Medicine, University of Utah, Salt Lake City, Utah, United States of America.

Abstract

Genome-wide association studies have identified a genetic variant at 3p14.3 (SNP rs1354034) that strongly associates with platelet number and mean platelet volume in humans. While originally proposed to be intronic, analysis of mRNA expression in primary human hematopoietic subpopulations reveals that this SNP is located directly upstream of the predominantly expressed ARHGEF3 isoform in megakaryocytes (MK). We found that ARHGEF3, which encodes a Rho guanine exchange factor, is dramatically upregulated during both human and murine MK maturation. We show that the SNP (rs1354034) is located in a DNase I hypersensitive region in human MKs and is an expression quantitative locus (eQTL) associated with ARHGEF3 expression level in human platelets, suggesting that it may be the causal SNP that accounts for the variations observed in human platelet traits and ARHGEF3 expression. In vitro human platelet activation assays revealed that rs1354034 is highly correlated with human platelet activation by ADP. In order to test whether ARHGEF3 plays a role in MK development and/or platelet function, we developed an Arhgef3 KO/LacZ reporter mouse model. Reflecting changes in gene expression, LacZ expression increases during MK maturation in these mice. Although Arhgef3 KO mice have significantly larger platelets, loss of Arhgef3 does not affect baseline MK or platelets nor does it affect platelet function or platelet recovery in response to antibody-mediated platelet depletion compared to littermate controls. In summary, our data suggest that modulation of ARHGEF3 gene expression in humans with a promoter-localized SNP plays a role in human MKs and human platelet function-a finding resulting from the biological follow-up of human genetic studies. Arhgef3 KO mice partially recapitulate the human phenotype.

PMID:
28542600
PMCID:
PMC5441597
DOI:
10.1371/journal.pone.0178095
[Indexed for MEDLINE]
Free PMC Article

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