Role of apelin on adipocyte : adipocyte differentiation and lipolysis.

Abstract

Adipocyte (fat cell), a passive energy storage site as fat, has been increasingly regarded as an important endocrine organ for its ability to secrete a variety of signaling molecules called adipokines. Apelin is a recently found novel adipokine, and is involved in various metabolic functions through the APJ receptor with endogenous ligand which is Gprotein- coupled. Expression of the APJ receptor in adipocytes implies that apelin also has autocrine/paracrine functions on adipocytes. In this study, we demonstrate that apelin inhibits adipocyte differentiation which is dependent on MAPK kinase/ERK1/2 signaling pathway. Moreover, we show that apelin increases the size of lipid droplets along with expression of one of the lipid droplets coating proteins known as perilipin, suggesting the protection role against lipolysis. And we found this effect relates to AMPK pathway. In addition, we prove that apelin effects of adipocytes are through the interaction with APJ receptor. Overall, our results reveal the apelin restraining effects of adipogenesis progress and protecting effects from lipolysis. This study may contribute the potential therapeutic target for obesity related metabolic disorders.