ABSTRACT: RNA-sequencing analysis of human platelet rRNA-depleted total RNA from two normal males and one female. The goal of this experiment was to identify genes expressed in unstimulated circulating platelets. Data from platelet polyA-mRNA has also been deposited at ArrayExpress, under accession number E-MTAB-715, https://www.ebi.ac.uk/arrayexpress/experiments/E-MTAB-715/ .
Project description:RNA-sequencing analysis of human platelet polyA-mRNA from a normal male. The goal of this experiment was to identify genes expressed in unstimulated circulating platelets.
Project description:Platelet activation is the key event triggering thrombus formation in physiological and pathological conditions, such as acute coronary syndromes. Current therapies using antiaggregants still fail to prevent thrombotic coronary events in a significant number of patients, indicating that the mechanisms modulating platelet response during activation need to be clarified. The evidence that platelets are capable of de novo protein synthesis in response to stimuli raised the issue of how the activity of megakaryocyte-derived mRNAs is regulated in these anucleate cell fragments. We applied a combined multi-omics approach to investigate this phenomenon in platelets from healthy donors activated in vitro with Collagen or Thrombin Receptor Activating Peptide. Combining HiRIEF LC-MS to transcriptome analysis by RNA-Seq allowed platelet proteome characterization at deep coverage, revealing a significant effect of either stimulus on proteome composition. In silico intron retention analysis was then applied to search for splicing events induced by platelet activation, coupled to unbiased proteogenomics, to correlate intron retention in resting platelets to intron removal by RNA splicing during activation. This allowed identification of a set of transcripts, specifically involved in platelet shape changes, showing reduced intron retention and high peptide representation at exon-exon junctions in activated vs resting platelets. These results indicate that RNA splicing events takes place in platelets during activation and that pre-mRNA maturation of specific transcripts is part of the activation cascade and could therefore provide novel molecular markers of platelet activation status in acute coronary syndromes and other pathological conditions.
Project description:To explore the diverse platelet microRNA (miRNA) expression between high platelet reactivity (HPR) and low platelet reactivity (LPR) patients with acute coronary syndromes (ACS), we enrolled a cohort of ACS patients and performed miRNA expression profiling of platelets from four HPR and four LPR patients using human miRNA microarray system. VerifyNow P2Y12 assay was applied to indentify HPR and LPR. Venous blood was drawn from the patients and was centrifuged to prepare platelets. Among the candidate differentially expressed miRNAs, miR-15b expression was further confirmed to be lower in platelets of 22 HPR patients than 17 LPR by quantitative reverse-transcription polymerase chain reaction (RT-qPCR). We enrolled a consecutive cohort of 290 ACS patients and assessed the platelet reactivity using VerifyNow P2Y12 assay. In this study, HPR was defined as M-bM-^IM-%300 platelet reactivity unit (PRU) while LPR <170 PRU. miRNA microarray analysis was performed in platelets of four HPR and four LPR patients with ACS.
Project description:Coronary artery disease (CAD) is the leading cause of human morbidity and mortality worldwide, underscoring the need to improve diagnostic strategies. Platelets play a major role, not only in the process of acute thrombosis during plaque rupture, but also in the formation of atherosclerosis itself. MicroRNAs are endogenous small non-coding RNAs that control gene expression and are expressed in a tissue and disease-specific manner. Therefore they have been proposed to be useful biomarkers. The aim of this study was to investigate whether differences in miRNA expression levels in platelets can be found (i) between patients with premature CAD and healthy controls and (ii) within healthy controls after and before aspirin and statin administration. In this case-control study we measured expression levels of platelet miRNAs using microarrays from 40 male patients with premature CAD and 40 age- and sex-matched healthy controls. Premature CAD was defined as a cardiac event before the age of 51 years. The patients were selected from the outpatient clinic of the Academic Medical Center (AMC) of Amsterdam, which is specialised in premature CAD. The control cohort was composed of 40 healthy Caucasian male volunteers, who were recruited by advertisement and who were matched with the cases for age and smoking habits. Individuals of this control cohort did not have a history of CVD, nor did they have a positive family history of CVD and they were not allowed to use any medication. Patients and controls were excluded when they suffered from diabetes. Most CAD patients use aspirin and statins as secondary prevention. The influence of these drugs on miRNA profiles is unknown. To assess the possible influence of medication on miRNA expression and to control for medication as confounding factor, we asked 27 volunteers in our control cohort to also use these drugs. We administered simvastatin 40 mg, once daily, for 6 weeks and during the last two weeks we added 100mg of acetyl salicylic acid, once daily. Blood samples including isolated platelets were collected at baseline in the absence of aspirin and statins and after six weeks of medication use. We also assessed platelet function using the Multiplate® Analyzer (Roche) in the absence of aspirin and statin use. In short, 300 µl whole blood was diluted with 300 µl 0.9% saline and stirred for 3 minutes at 37 ºC. Adenosine diphosphate (ADP) was added in a final concentration of 2.5 ?mol/L to initiate platelet aggregation. Aggregation was measured for 6 minutes and was reported in arbitrary aggregation units plotted against time. Also, the area under the aggregation curve (AUC) was measured. All samples were measured in the absence and presence of 200 ?mol/L indomethacin (20 min incubation with blood) to mimic the effect of aspirin use. We calculated the percentage reduction in AUC after incubation with indomethacin as an in vitro measure of the effect of aspirin use on whole blood platelet aggregation.
Project description:Platelets contain abundant miRNAs, however, the biogenesis pathway of miRNAs in anucleate platelets is unclear. Platelet-rich plasma was diluted in washing buffer and the platelet suspension was centrifuged to isolated pure platelets.Finally, platelets were recovered in suspension buffer at the concentration of 4–5×10^8 platelets/ml. Aliquots of the platelet suspensions were activated in the presence of 2.5 mM CaCl2 with 0ng/ml or 1 ng/ml thrombopoietin (TPO)
Project description:Platelets have multiple roles in cancer cell metastasis. In this work we employed exon microarray technology to address platelet gene expression in metastatic non small cell lung cancer versus controls without cancer. We found that 197 of the 200 genes with the most significantly altered expression levels had their expression levels downregulated. Retrospective observational study. Total of 12 samples: 6 controls and 6 lung cancer samples.
Project description:The goal of this experiment was to explore how human platelets affect the transcriptional responses of primary human CD14+ blood monocytes to lipopolysaccharide (LPS), and NLRP3 activation with Nigericin. For this purpose, we analyzed the mRNA expression of 770 myeloid-specific transcripts using the nCounter® Nanostring Human Myeloid Innate Immunity Panel v2. We isolated classical monocytes (CD14+CD16−) from the peripheral blood of healthy volunteers. Monocytes were derived from PBMCs using negative selection with the EasySep™ Human Monocyte Isolation Kit from STEMCELLTM Technologies. We modified this process by either including or excluding a platelet-depleting cocktail, creating two groups: \\"Standard Monocytes (StdMo)\\" and \\"Platelet-depleted Monocytes (PdMo).\\" To examine the impact of platelets further, we supplemented PdMos with fresh autologous platelets at a ratio of 50 platelets per monocyte, resulting in a third group, \\"PdMo + Plts.\\" StdMos were prepared according to the standard protocol provided by the EasySep™ Kit. For the PdMos, a Platelet Removal Component (50 µl ml−1) from the kit was used during isolation. We also reconstituted platelet-depleted monocytes with platelets and analyzed platelets alone to determine their specific mRNA contributions. The groups—StdMo, PdMo, PdMo + Plts, and platelets alone—were then exposed to 2 ng/ml of Ultrapure LPS (from E. coli O111:B4) for 4.5 hours, or stimulated with LPS for 3 hours followed by inflammasome activation with Nigericin (10 µM) for 90 min before extracting RNA for analysis.
Project description:Using custom spotted oligonucelotide platelet-focused arrays, platelet samples were compared. 48 health controls, 23 reactive thrombocytosis (RT) and 24 essential thrombocythemia (ET) samples were compared. An 11-biomarker gene subset was identified that discriminated among the three cohorts with 86.3% accuracy. 70 mer oligonucleotides were spotted in quadruplicate and hybridized versus reference RNA in two color method. Spiked control RNAs were also included.
Project description:Platelets are major players in the process of intravascular thrombus formation. Current therapeutic strategies still fail to prevent thrombotic coronary events in a substantial number of patients, indicating that the complex mechanisms modulating platelet response during activation are not fully elucidated. The evidence that platelets are capable of de novo protein synthesis has raised the issue of whether and how these resident mRNAs are regulated in circulating platelets. Among the several mechanisms potentially involved, mRNA splicing may be relevant. Purified platelet-rich plasmas from healthy volunteers were collected and in vitro activated with collagen or Thrombin Receptor Activating Peptide (TRAP). Transcriptome profiling by RNA-Seq and in silico intron representation analysis were applied to search for the presence of pre-mRNA molecules and splicing events affected by platelet activation. HiRIEF LC-MS allowed platelet proteome characterization at deep coverage to investigate a possible correlation between splicing events and protein levels. By comparing computational and wet-lab analyses it was possible to identify a set of transcripts influenced at both intron and protein level.
Project description:In sickle cell disease, ischemia-reperfusion injury and intravascular hemolysis produce endothelial dysfunction and vasculopathy characterized by reduced nitric oxide (NO) and arginine bioavailability. Recent functional studies of platelets in patients with sickle cell disease reveal a basally activated state, suggesting that pathological platelet activation may contribute to sickle cell disease vasculopathy. Studies were therefore undertaken to examine transcriptional signaling pathways in platelets that may be dysregulated in sickle cell disease. We demonstrate and validate here the feasibility of comparative platelet transcriptome studies on clinical samples from single donors, by the application of RNA amplification followed by microarray-based analysis of 54,000 probe sets. Data mining an existing microarray database, we identified 220 highly abundant genes in platelets and a subset of 72 relatively platelet-specific genes, defined by more than 10-fold increased expression compared to the median of other cell types in the database with amplified transcripts. The highly abundant platelet transcripts found in the current study included 82% or 70% of platelet abundant genes identified in two previous gene expression studies on non-amplified mRNA from pooled or apheresis samples, respectively. On comparing the platelet gene expression profiles in 18 patients with sickle cell disease in steady state to 12 African American controls, at a 3-fold cut-off and 5% false discovery rate, we identified ~100 differentially expressed genes, including multiple genes involved in arginine metabolism and redox homeostasis. Further characterization of these pathways using real time PCR and biochemical assays revealed increased arginase II expression and activity and decreased platelet polyamine levels. These studies suggest a potential pathogenic role for platelet arginase and altered arginine and polyamine metabolism in sickle cell disease and provide a novel framework for the study of disease-specific platelet biology. Experiment Overall Design: There are 18 sickle cell samples and 12 control samples from healthy African American volunteers.