MicroRNA Biomarkers Released by Platelet Activation

Abstract

MicroRNAs are a group of small noncoding RNA molecules that have been implicated in a variety of human diseases. Because of their remarkable stability and abundant quantity in blood, circulating microRNAs are promising as noninvasive biomarkers for diagnosis or prognosis. Platelets are likely to be a substantial contributor to circulating miRNAs. Upon activation, platelets shed membrane-bound microparticles, microvesicles and protein complexes into circulation. Recent studies suggest that circulating miRNAs are protected by encapsulation in vesicles or binding with Argonaute2 (Ago2) protein complex from blood RNase activity. However, the mechanisms of how platelets release miRNAs into circulation, and the role of platelet activation in miRNA release remains unclear. Therefore, I characterized four highly expressed platelet-released microRNAs: miR-16; miR-142-3p; miR-223 and let-7a, using size-exclusion chromatography. My results show that miRNAs are released by platelet activation. Further, my data suggests that platelet-released miRNAs are primarily associated with vesicle-free protein complexes rather than microparticles and microvesicles.