Fig. 1

Schematic of circulatory miRNAs. A Exosomal microvesicles can be released by several types of cell within the cardiovascular system and enter into the circulatory system. B The biogenesis of miRNAs: i) biogenesis begins in the cell nucleus with the transcription of the DNA into large pri-miRNAs which are cleaved by the Drosha enzyme into pre-miRNAs that can be transported into the cytoplasm, ii) The Dicer enzyme cleaves the pre-miRNA into immature miRNA duplexes of 21 to 25 nucleotides and then to a single stranded mature miRNA, iii) miRNAs can be incorporated into a RNA-induced silencing complex (RISC) which can bind or partially-bind to mRNA and inhibit translation or promote degradation, iv) pre-miRNAs and mature miRNAs can be secreted from the cell in exosomes or lipid vesicles as well as bound to RNA-binding proteins and lipoproteins. C microvesicles can enter the circulatory system where they can be detected from blood samples (and other bodily fluids) for the purposes of prognosis, diagnosis and as therapeutic targets