The causal mechanisms of common diseases are only marginally illuminated by genetic variants found in genome wide association studies (GWAS) using single nucleotide polymorphism (SNPs). Platelet pathways reflecting hemostasis and thrombosis are the underlying substrate for many cardiovascular diseases and related acute events. To overcome GWAS limitations, genomic studies must integrate molecular surrogates for platelet-related phenotypes assayed in cell-based models derived from individuals of known genotypes and phenotypes. In our GWAS study of native platelet aggregation and aggregation in response to low dose aspirin (GeneSTAR, Genetic Study of Aspirin Responsiveness), 64 loci were associated with native platelet aggregation at genome wide significance (p<5x10""""""""^) while 57 were associated with platelet responsiveness to aspirin, many replicated in both races. Although we are performing functional genomics studies to elucidate findings in known genes (PEAR1, RGL3, and MET), most signals were in intergenic regions (38%), or in introns (55%), with only 1.6% producing missense mutations in exons. Mechanistic interpretation is uncertain re which gene(s) are up- or down-regulated based on SNP modifications. In 3 phases, we will (1) create pluripotent stem cells (iPS) from peripheral blood mononuclear cells, and then differentiate these stem cells into megakaryocytes (2) efficiently produce iPS and megakaryocytes using a novel pooling method, and (3) produce iPS and megakaryocytes from 400 subjects in GeneSTAR (200 whites, 200 African Americans), selected based on specific hypotheses derived from GWAS signals in native and post aspirin platelet function;characterize genetic mRNA transcripts using a comprehensive Affymetrix exon array;measure protein expression for transcripts of interest using mass spectrometry;examine mRNA and protein expression patterns for each GWAS signal to determine the functional pathway(s) involved in native platelet phenotypes;and examine the functional genomics of variations in aspirin response using our prior genotyped and phenotyped population. This project at Johns Hopkins will be conducted by an interdisciplinary group of expert investigators. (Phase 1 and II, PI, L Cheng, Hematology Division, Dept of Medicine;Phase III PI, L Becker, GeneSTAR Research Program),

Public Health Relevance

Precise information about the functional processes in megakaryocytes and platelets may lead to innovative and tailored approaches to risk assessment and novel therapeutic targets to prevent first and recurrent cardiovascular and related acute thrombotic events. Further, Phase I and II developmental research will contribute to new knowledge that would positively affect the transfusion of iPS-derived hematopoietic cells in patients with such cell deficiencies.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project--Cooperative Agreements (U01)
Project #
5U01HL107446-03
Application #
8501668
Study Section
Special Emphasis Panel (ZHL1-CSR-N (F1))
Program Officer
Qasba, Pankaj
Project Start
2011-07-05
Project End
2016-06-30
Budget Start
2013-07-01
Budget End
2014-06-30
Support Year
3
Fiscal Year
2013
Total Cost
$2,209,641
Indirect Cost
$860,314
Name
Johns Hopkins University
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
001910777
City
Baltimore
State
MD
Country
United States
Zip Code
21218
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Eicher, John D; Chami, Nathalie; Kacprowski, Tim et al. (2016) Platelet-Related Variants Identified by Exomechip Meta-analysis in 157,293 Individuals. Am J Hum Genet 99:40-55
Chen, Kang; Bai, Hao; Liu, Yanfeng et al. (2015) EphB4 forward-signaling regulates cardiac progenitor development in mouse ES cells. J Cell Biochem 116:467-75
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Qayyum, Rehan; Becker, Diane M; Yanek, Lisa R et al. (2015) Greater collagen-induced platelet aggregation following cyclooxygenase 1 inhibition predicts incident acute coronary syndromes. Clin Transl Sci 8:17-22
Smith, Cory; Abalde-Atristain, Leire; He, Chaoxia et al. (2015) Efficient and allele-specific genome editing of disease loci in human iPSCs. Mol Ther 23:570-7
Chou, Bin-Kuan; Gu, Haihui; Gao, Yongxing et al. (2015) A facile method to establish human induced pluripotent stem cells from adult blood cells under feeder-free and xeno-free culture conditions: a clinically compliant approach. Stem Cells Transl Med 4:320-32
Chen, Tong; Wang, Fen; Wu, Mengyao et al. (2015) Development of hematopoietic stem and progenitor cells from human pluripotent stem cells. J Cell Biochem 116:1179-89
Xie, Yinliang; Bai, Hao; Liu, Yanfeng et al. (2015) Cooperative Effect of Erythropoietin and TGF-? Inhibition on Erythroid Development in Human Pluripotent Stem Cells. J Cell Biochem 116:2735-43
Huang, Xiaosong; Wang, Ying; Yan, Wei et al. (2015) Production of Gene-Corrected Adult Beta Globin Protein in Human Erythrocytes Differentiated from Patient iPSCs After Genome Editing of the Sickle Point Mutation. Stem Cells 33:1470-9

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