Figure 2.

miRNAs processing and releasing by adipocytes and their influence on metabolic syndrome, obesity and cancer. Adipocytes are the main source of circulating miRNAs in mice and human. The process of miRNA maturation begins in the nucleus with the gene transcription by RNA polymerase II or III in pri-miRNA. Following the maturation process, the enzyme DROSHA and its Pasha cofactor leads to the pre-miRNA, which are exported to the cytosol by the Exportin-5 protein, and further processed by Dicer enzyme, leading to the mature miRNA. It is taken into the RISC silencing complex and then become an active post-transcriptional regulator. This may occur by cell free miRNA release, associated with apoptotic body, exosomes, or HDL. miRNAs can act influencing different types of cells. Circulating miRNAs are able to control: (I) the expression of several genes related to adipogenesis, (II) the adipocyte differentiation and lipid metabolism impacting obesity, (III) the expression of membrane proteins responsible for the glucose homeostasis and insulin resistance, (IV) the metabolic diseases development, and (V) the cancer establishment and progression as oncomiR molecules.