Platelet microRNA-mRNA coexpression profiles correlate with platelet reactivity

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 highpriority 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. IntroductionOn rupture of atherosclerotic plaques, some persons form occlusive platelet thrombi whereas other persons repair the wound without occluding the vessel. The extreme interindividual variation in platelet reactivity probably contributes to the variation in both risk and clinical outcome of ischemic vascular disease because platelet hyper-reactivity has prospectively been shown to be a risk for recurrent coronary syndromes. 1 Although heritability strongly influences the interindividual variation in platelet reactivity, [2][3][4] there is a lack of understanding of the responsible genetic and molecular mechanisms. To understand better the basis for human platelet function, it is critical to define the genes that are expressed in the tissue of interest. We have previously used platelet RNA expression analyses from platelets of differing reactivity to identify differentially expressed (DE) platelet transcripts and proteins. 5 During the course of our studies, we found that a DE platelet microRNA (miRNA) altered the expression of VAMP8, a critical component of platelet granule exocytosis. miRNAs are small (ϳ 22 nucleotides) noncoding RNAs that function post-transcriptionally in regulating gene expression by inducing mRNA degradation or translation inhibition, generally by targeting the 3Ј-untranslated region (UTR) of mRNAs. 6 miRNAs were initially identified as regulators of genes involved in development but have since been shown to affect a broad range of normal physiologic processes, including hematopoietic lineage commitment, as well as pathologic conditions. 7,8 More than 1000 miRNAs have been identified, which are estimated to regulate most (Ͼ 60%) coding genes. 9 The cellular impact of most miRNA-mRNA interactions is a fine-tuning of protein output, and not a major repression of expression. 10 Importantly, as little as a 20% reduction in miRNA levels can produce a disease phenotype. 11 Recent data demonstrate a role for miRNAs in both normal and diseased human megakaryocytopoiesis. 8,12-17 Although we and others have observed miRNAs in platelets, 15,[18][19][20][21][22][23] th...

The clinical significance of platelet microparticle-associated microRNAs

“…A year later, the same group established a correlation between platelet microRNA-mRNA coexpression profiles with platelet reactivity [28]. Two years later, Edelstein et al [29] narrowed the gap by showing that (i) miR-376c levels were inversely correlated with PCTP mRNA levels, PC-TP protein levels and PAR4 reactivity, and that (ii) miR376c regulated expression of PC-TP in human megakaryocytes [29].…”

Hematopoietic MicroRNA-126 Protects against Renal Ischemia/Reperfusion Injury by Promoting Vascular Integrity

“…44 Alternatively, the increased number of BM-derived EC that line the microvascular network of the kidney of the LV-126 mice could serve as a source of miR-126 via the production of microparticles 45 ; it was recently shown that, under certain conditions, such particles can cross the tubular basement membrane. 46 In addition, activated platelets may be involved because miR-126 is among the most abundant microRNAs in platelets, 47,48 and they could serve as a transporter of miR-126 to the site of injury. 49 Because EPCs can take up platelets and their molecular content, 50 platelets could also add to EPC function through miR-126 transfer.…”

The Two Faces of Thrombosis: Coagulation Cascade and Platelet Aggregation. Are Platelets the Main Therapeutic Target?

“…However, the main question about platelet miRNAs concerns their possible role in regulating platelet reactivity. It has been reported that platelets contain more mRNAs that encode proteins that inhibit platelet activation to maintain platelets in a resting state [47]. Regarding activation, platelets miRNAs may be differentially expressed, thus some of them may predict platelet activation/reactivity [47].…”

“…It has been reported that platelets contain more mRNAs that encode proteins that inhibit platelet activation to maintain platelets in a resting state [47]. Regarding activation, platelets miRNAs may be differentially expressed, thus some of them may predict platelet activation/reactivity [47]. In light of the published data, we have tried to elucidate the molecular changes induced in activated platelets, looking at miRNome and proteome reorganization upon activation [46].…”