PNPLA3 in largemouth bass (Micropterus salmoides): Molecular cloning, functional characterization, and its role in high glucose-induced lipid synthesis

Abstract

This study aimed to characterize the full-length cDNA of pnpla3 in Micropterus salmoides, and evaluate its role in high glucose-induced lipid synthesis. The full-length cDNA of pnpla3 was composed of 3366 nucleotides that encoded 550 amino acids. The molecular weight of Pnpla3 was 60.41044 kDa. Pnpla3 protein contained one I-superfamily conotoxin signature, one patatin domain, one (G/A) xGxxG nucleotide domain, one GxSxG lipase motif, one DGG lipase motif, one Ser47-Asp166 catalytic dyad motif, one brummer box domain, and one 148I residue. The high mRNA levels of pnpla3 were got in perivisceral fat followed by liver, white muscle, brain and intestine. High carbohydrates diets and glucose administration resulted in a significant up-regulation of pnpla3 mRNA levels in the liver and muscle. In the in vitro study, PNPLA3 gene silencing significantly decreased pnpla3 mRNA levels and its protein content, and lipid droplets area in hepatocytes. Isoleucine treatment reduced pnpla3 mRNA levels, total triglyceride and cholesterol contents, and lipid droplets area in hepatocytes subjected to high glucose. Overall, M. salmoides pnpla3 is highly conserved, and pnpla3 involved in the regulation of glucose metabolism. Isoleucine could alleviate high glucose-induced lipid accumulation in M. salmoides; this might be achieved through the down-regulation of pnpla3 expression.