NextGen Consortium: Functional Genomics of Platelet Aggregation Using iPS and Derived Megakaryocytes
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PROVIDER: PRJNA312864 | ENA |
REPOSITORIES: ENA
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Project description:<p>The causal mechanisms of common diseases and their therapies have been only marginally illuminated by genetic variants identified in genome wide association studies (GWAS) utilizing single nucleotide polymorphism (SNPs). Platelet activation pathways reflecting hemostasis and thrombosis are the underlying substrate for many cardiovascular diseases and related acute events. To overcome GWAS limitations, genomic studies are needed that 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 phenotypes and aggregation in response to low dose aspirin in 2200 subjects (GeneSTAR, Genetic Study of Aspirin Responsiveness), important genome wide "signals" (p<5x10-8) associated with native platelet aggregation and important "signals" associated with platelet responsiveness to aspirin were identified and replicated. Although we are currently performing functional genomics studies to elucidate our most promising findings in known genes (PEAR1, MET, PIKC3G), most "signals" occurred in intergenic regions or in introns. Mechanistic interpretation is limited by uncertainty as to which gene(s) are up- or down-regulated in the presence of most SNP modifications. In this 3 phase proposal, we will (1) create pluripotent stem cells (iPS) from peripheral blood mononuclear cells, and then differentiate these stem cells into megakaryocytes (2) develop an efficient strategy to produce iPS and megakaryocytes using a novel pooling method, and (3) produce iPS and megakaryocytes from 250 subjects in GeneSTAR (European Americans and 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 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 responsiveness to aspirin using our prior genotyped and phenotyped population. Precise information about the exact 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 thrombotic events.</p>
| phs001074 | dbGaP
Project description:NextGen Consortium: Functional Genomics of Platelet Aggregation Using iPS and Derived Megakaryocytes
| PRJNA312865 | ENA
Project description:The Stem Cell Leukemia (Scl or Tal1) protein forms part of a multimeric transcription factor complex required for normal megakaryopoiesis. However, unlike other members of this complex such as Gata1, Fli1 and Runx1, mutations of Scl have not been observed as a cause of inherited thrombocytopenia. We postulated that functional redundancy with its closely related family member, Lymphoblastic Leukemia 1 (Lyl1) might explain this observation. To determine if Lyl1 can substitute for Scl in megakaryopoiesis, we examined the platelet phenotype of mice lacking one or both factors in megakaryocytes. Conditional Scl knockout mice crossed with transgenic mice expressing Cre recombinase under the control of the mouse platelet factor 4 (Pf4) promoter generated megakaryocytes with markedly reduced but not absent Scl. These Pf4SclcKO mice had mild thrombocytopenia and subtle defects in platelet aggregation. However, Pf4SclcKO mice generated on a Lyl1-null background (double knockout, DKO mice) had severe macrothrombocytopenia, abnormal megakaryocyte morphology, defective pro-platelet formation and markedly impaired platelet aggregation. DKO megakaryocytes, but not single knockouts, had reduced expression of Gata1, Fli1, Nfe2 and many other genes that cause inherited thrombocytopenia. These gene expression changes were significantly associated with shared Scl and Lyl1 E-box binding sites that were also enriched for Gata1, Ets and Runx1 motifs. Thus, Scl and Lyl1 share functional roles in platelet production and function by regulating expression of partner proteins including Gata1 and Fli1. We propose that this functional redundancy provides one explanation for the absence of Scl and Lyl1 mutations as a cause of inherited thrombocytopenia.
2020-12-21 | GSE125025 | GEO
Project description: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'UTRs 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. Total RNA from the platelets of 19 donors was harvested and labeled with Hy3. Reference RNA (a pool of all samples) was labeled with Hy5. This submission represents the miRNA expression component of the study.
2011-09-26 | E-GEOD-27917 | biostudies-arrayexpress
Project description:Immune thrombocytopenia (ITP) is a common platelet disorder in pediatric patients. Pediatric and adult ITP have been associated with sialic acid alterations, but the pathophysiology of ITP remains elusive, and ITP is often a diagnosis of exclusion. Our analysis of pediatric ITP plasma samples showed increased anti-Thomsen-Friedenreich antigen (TF-antigen) antibody representation, suggesting increased exposure of the typically sialylated and cryptic TF-antigen in these patients. The O-glycan sialyltransferase St3gal1 add sialic acid specifically on the TF-antigen. To understand if TF-antigen exposure associates with thrombocytopenia, we generated a mouse model with targeted deletion of St3gal1 in megakaryocytes (MK) (St3gal1MK-/-). TF-antigen exposure was restricted to MKs and resulted in thrombocytopenia. Deletion of Jak3 in St3gal1MK-/- mice normalized platelet counts implicating involvement of immune cells. Interferon-producing Siglec H-positive bone marrow (BM) immune cells engaged with O-glycan sialic acid moieties to regulate type I interferon (IFN-I) secretion and platelet release (thrombopoiesis), as evidenced by partially normalized platelet count following and inhibition of interferon and Siglec H receptors. Single cell RNAseq determined that TF-antigen exposure by MKs primed St3gal1MK-/- BM immune cells to release IFN-I. Single cell RNAseq further revealed a new population of immune cells with a plasmacytoid dendritic cell (pDC)-like signature and concomitant upregulation of immunoglobulin re-arrangement gene transcripts Igkc and Ighm, suggesting additional immune regulatory mechanisms. Thus, aberrant TF-antigen moieties, often found in pathological conditions, regulate immune cells and thrombopoiesis in the BM, leading to reduced platelet count.
2021-06-29 | GSE179067 | GEO
Project description:ChIP-seq assay was performed with anti-p45 antibody using in vitro cultured primary megakaryocytes to identify direct p45 target genes in megakaryocytes. This analysis revealed genes that regulate platelet function, which were not known previously to be p45-regulated. ChIP was performed using a day-3 primary culture of megakaryocytes from E13.5 fetal livers of wild-type mice with an anti-p45 antibody.
2013-11-01 | E-GEOD-42249 | biostudies-arrayexpress
Project description:ChIP-seq assay was performed with anti-p45 antibody using in vitro cultured primary megakaryocytes to identify direct p45 target genes in megakaryocytes. This analysis revealed genes that regulate platelet function, which were not known previously to be p45-regulated.
2013-11-01 | GSE42249 | GEO
Project description: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'UTRs 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.
2011-09-27 | GSE27917 | GEO
Project description:We developed a novel differentiation system that directionally induces hESCs into megakaryocytes and functional platelet in vitro by highly mimicking the in vivo developmental process of megakaryocytes and platelets. We then performed gene expression profiling analysis using data obtained by RNA-seq at different stages of differentiation during the differentiation of hESCs into megakaryocyte lineages.
2024-08-14 | GSE216593 | GEO
Project description:Megakaryocytes are bone marrow (BM) resident cells that derive from hematopoietic stem cells. A pivotal function of megakaryocytes is the generation of platelets through the release of long protrusions called proplatelets into sinusoidal vessels. single-cell RNA-sequencing on murine BM megakaryocytes has previously revealed transcriptional heterogeneity with segmentation into four distinct categories. These studies postulated functions beyond platelet production with evidence for immunoregulatory and stem cell niche supporting subtypes, as well as a cycling population. The spatial context and transcriptional heterogeneity of megakaryocytes is of great interest as localization of for instance the vasculature is a necessity for platelet production. For single-cell RNA sequencing this spatial orientation is however lost due to the dissociation of tissues. Recent technological advances have enabled the interrogation of gene expression profiles of tissues in situ. This enables the integration of morphological, situational and transcriptional information to classify cells in the context of their microenvironment. In the following we present, for the first time, the application of this technology to BM megakaryocytes at a single cell level.
2023-04-27 | GSE224838 | GEO