The effects of suppressor of cytokine signalling 3 in glucose intolerance of Japanese flounder (Paralichthys olivaceus).

To explore molecular targets for regulating glucose metabolism in carnivorous fish, the glucose tolerance test was carried out on the Paralichthys olivaceus. The concentration of glucose and insulin in serum was measured at 0, 1, 3, 5, 7, 9, 12, 24 and 48 h after intraperitoneal (IP) injection. The concentration of insulin was the lowest after 3 h of glucose injection, and that of glucose reached the highest after 5 h. Therefore, 0 h (IP0) was chosen as control group, and 3 h (IP3) and 5 h (IP5) were selected as experimental groups, for which the liver samples at three time points were used for high-throughput sequencing. Although there were no significant Kyoto Encyclopedia of Genes and Genomes and Gene Ontology functional enrichment, the differential genes, including mitogen-activated protein kinase binding protein 1, glycosyltransferase, suppressor of cytokine signalling 3 (SOCS3) and CCAAT/enhancer-binding protein α, were closely related to glucose metabolism. The open reading frame of SOCS3 encoded 225 amino acids, including conserved domains SH2 and SOCS3-box. The SOCS3 was knocked down by specific siRNA in the primary hepatocyte of P. olivaceus. Results showed that the gene expression of insulin receptor substrate 1, protease B1, GLUT2, pyruvate kinase and glucokinase increased significantly after knocking down SOCS3. Meanwhile, the phosphatidylinositol-3-hydroxykinase and glucose-6-phosphatase decreased significantly. The results of this study indicated that siSOSC3 enhanced the sensitivity of the insulin signalling pathway to promote glucose transport, thereby affecting gluconeogenesis and glycolysis to maintain glucose homeostasis.