Platelet Activation Affects Pre-mRNA Maturation of a Group of Transcripts Useful as Markers of Acute Coronary Syndromes

Background: Platelets represent a major player in the process of intravascular thrombus formation. Despite significant advancements in antithrombotic therapy, current 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 various mechanisms potentially involved, mRNA splicing may be potentially relevant. Methods: Purified platelet-rich plasma from healthy volunteers were collected and in vitro activated with collagen or thrombin receptor activating peptide. Transcriptome analysis by RNA-Seq and in silico intron retention analysis were applied to search for 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. Results: Extensive computational analysis following RNA-Seq revealed several splicing events occurring in activated platelets. By applying unbiased proteogenomics, we correlated intron retention events in quiescent platelets to exon-exon junctions frequency after activation. In this way we identified a set of transcripts presenting reduced intron retention and high peptide representation at exon-exon junctions in activated vs resting platelets. Conclusions: The observed results indicate that pre-mRNA maturation of platelet-specific transcripts could be monitored and used as marker of platelet activation in acute coronary syndromes. Acknowledgement: Research supported by MIUR (FIRB RBFR12W5V5_003), MOH (GR-2011-02347781), CNR (Flagship Project InterOmics) and Genomix4Life