[Alteration in the expression of platelet microRNAs in diseases with abnormal platelet activation]

MicroRNAs (miRNA) are short, non-coding RNAs consisting of 18-25 nucleotides that regulate posttranscriptionally the gene expression involved in the regulation of physiological processes of the cells. Their key role is to modulate the translation of target mRNAs via binding to complementary sequences within the 3' UTRs of mRNAs resulting in altered protein synthesis or even the degradation of mRNAs. miRNAs are carried not only by cells with nucleus, but also in platelets, red blood cells, and they are present in the circulation, in urine and in other body fluids as well. The fact about functional miRNAs in platelets without nucleus having a half-life of 8-12 days was questioned for a long time, thus it was also obscure whether platelets are able to produce proteins de novo when being exposed to different challenges. In the last few years, several publications have described the expression and function of certain platelet mRNAs with their regulatory miRNAs in terms of regulation of cell activation, especially in diseases in which platelet activation status is elevated, such as in type 2 diabetes mellitus or in sepsis. Apart from their pathophysiological role, miRNAs may be applied as potential new biomarkers in the investigation or differential diagnosis of these clinical conditions. This review article sought to summarize the recent findings about platelet miRNAs focusing on their altered expression in diabetes and sepsis. Orv Hetil. 2018; 159(47): 1962-1970.