Mechanisms of lipid metabolism promoted by berberine via peroxisome proliferator-activated receptor gamma during in vitro maturation of porcine oocytes

Abstract

This study was conducted to explore the molecular mechanisms of berberine (Ber) via peroxisome proliferator-activated receptor gamma (PPARG) in promoting in vitro maturation (IVM) and lipid metabolism of porcine oocytes. Our results showed that expression changes in PPARG influenced IVM and the lipid droplet content of porcine oocytes. Moreover, c-Jun-N-terminal kinase (JNK) inhibitor modified the effect of PPARG agonist on IVM and lipid droplet content of porcine oocytes, and Ber significantly reduced lipid droplet content. Activation of PPARG upregulated the transcription level of microRNA-192 (miR-192), significantly promoted the expression of fatty acid binding protein 3 (FABP3) and steroid regulatory element binding transcription factor 1 (SREBF1) and PPARG, inhibited phosphorylation of PPARG, and enhanced JNK phosphorylation. Ber and overexpression of miR-192 upregulated the transcription level of miR-192 in porcine oocytes; significantly decreased the expression of FABP3, SREBF1, and PPARG; increased PPARG phosphorylation; and inhibited JNK phosphorylation. Otherwise, JNK inhibitor reduced the effects of PPARG agonist. In conclusion, Ber may activate the expression of miR-192, downregulate the expression level of PPARG and lipid synthesis-related genes, increase PPARG phosphorylation, and reduce JNK phosphorylation to enhance lipid metabolism, which is beneficial to improve porcine oocyte quality of IVM.

Keywords: PPARG; berberine; in vitro maturation; lipid metabolism; porcine oocyte.