miR-378a: a new emerging microRNA in metabolism.

Metabolic diseases, such as type 2 diabetes or obesity, are the consequence of the disruption of the organism's metabolic pathways. The discovery of small non-coding RNAs-microRNAs (miRNAs)-as post-transcriptional gene regulators opened new doors for the development of novel strategies to combat said diseases. The two strands of miR-378a, miR-378a-3p, and miR-378a-5p are encoded in the Ppargc1b gene and have an active role in the regulation of several metabolic pathways such as mitochondrial metabolism and autophagy. Recent studies recognized miR-378a as an important regulator of energy and glucose homeostasis, highlighting it as a potential target for the improvement of metabolic dysregulation. In the present review, the current knowledge on miR-378a will be discussed with a particular emphasis on its biological functions and mechanisms of action in metabolism, mitochondria, and autophagy.