An investigation of the platelet transcriptome and its relationship to platelet function

The platelet is an anucleate cell fragment released into the blood from its progenitor cell the megakaryocyte (MK). It was the aim of this thesis to explore the relationship between platelet functional responses and variation in the platelet transcriptome. Rigorous quality assessment of platelet RNA was completed to determine its suitability for DNA microarray investigation. The transcriptomes of individuals homozygous for the major and minor haplotypes of the collagen receptor GPVI, which show differences in signalling responses, were compared using cDNA microarrays. Fifty-two differentially expressed transcripts were identified and ten were selected for further validation. Two transcripts were confirmed as differentially expressed between the haplotypes and the relationship between protein and transcript abundance was investigated. In a second, larger study, platelet RNA from 37 individuals from the ‘extreme ends’ and the mid-range of the distribution of platelet response was isolated. Using whole genome coverage DNA microarrays, 69 transcripts were identified that showed variation in abundance that correlated with platelet response. The proteins encoded by the 69 transcripts were investigated in detail and functionally related proteins were identified, including groups of proteins involved in transcription, cell signalling, metabolism and membrane interactions. Finally, the catalogue of transcripts identified as present in the platelet transcriptome was studied. This data was compared to published platelet and MK transcriptomes and examined for known and novel platelet transcripts, focusing on transcripts encoding transmembrane proteins. In conclusion, this thesis describes in detail the platelet transcriptome in healthy individuals. In addition, genes have been identified whose transcript abundance correlates with platelet functional response, thus identifying genes that play key regulatory roles in platelet function. A number of these genes have since been shown to be risk factors for coronary artery disease thus highlighting the role of platelets in this common disease.EThOS - Electronic Theses Online ServiceGBUnited Kingdo