DUSP9对高脂喂养胰岛素抵抗C57小鼠胆固醇、糖异生的影响

Effects of DUSP9 on cholesterol and gluconeogenesis in high-fat diet induced insulin resistance C57 mice

目的探讨DUSP9基因对高脂喂养诱导的胰岛素抵抗C57小鼠胆固醇、糖异生的影响。方法将成功构建的pEGFP-DUSP9裸质粒注射随机选取的高脂喂养小鼠(HD组,n=10),以空载pEGFP-N1注射的高脂喂养小鼠为对照(HE组,n=10),普食喂养的为阴性对照(NC组,n=10),质粒注射48h后分别取各组小鼠血清、肝组织,检测总胆固醇(TC)、低密度脂蛋白胆固醇(LDL-C)、空腹血糖(FBG),空腹胰岛素(FINS)等指标;实时荧光定量PCR(QPCR)法检测各肝组织中DUSP9、脂代谢相关基因固醇元件结合蛋白2(SREBP2)、低密度脂蛋白受体(LDLr)、糖异生关键酶-磷酸烯醇式丙酮酸羧化酶(PEPCK)mRNA表达的变化,Western blot法检测DUSP9蛋白表达水平。结果 HD、HE组小鼠FBG、FINS、TC、LDL-C水平较NC组明显升高(P<0.01);HD组小鼠肝脏中DUSP9mRNA、蛋白表达水平均较HE组显著升高(P<0.01),SREBP2、LDLr mRNA表达水平均显著增加(P<0.01),PEPCK mRNA表达水平明显下调(P<0.01);HD组小鼠48h血清TC、LDL-C水平与HE组比较,差异无统计学意义(P>0.05)。结论 DUSP9可能通过上调SREBP2、LDLr水平改善高脂喂养胰岛素抵抗C57小鼠的胆固醇代谢,减少PEPCK mRNA的表达水平从而导致肝糖输出减少,FBG水平降低。

Objective To investigate the effects of dual specificity protein phosphatases 9（DUSP9） on cholesterol and gluconeogenesis in high-fat diet induced insulin resistance C57 mice.Methods Expression vector for DUSP9 gene was successfully constructed.Naked plasmids of pEGFP-DUSP9 were injected into high-fat diet mice（HD group,n=10） which were randomly selected,pEGFP-N1 plasmids were injected into high-fat diet mice（HE group,n=10） as the control group,and the normal-chow diet group（NC group,n=10） as negative control group,respectively.The blood serum and liver tissue in each group were collected at 48 h after plasmid transfection.The levels of total cholesterol（TC）,low-density lipoprotein cholesterol（LDL-C）,fasting blood glucose（FBG）,fasting insulin（FINS） were detected.The mRNA expression of DUSP9,SREBP2 and LDLr were examined by QPCR.DUSP9 protein levels were determined by Western blot.Results Compared with the NC group,the body weight,FBG,FINS,TC,LDL-C levels in the HD and the HE groups were significantly increased（P0.05）.DUSP9 mRNA and protein levels in the HD group were obviously increased compared with the HE group.The expression of SREBP2 and LDL-R mRNA were increased and the mRNA levels of PEPCK were down-regulated compared with HE group.The serum levels of TC and LDL-C after transfection 48 h were not changed in the HD group（all P0.05）.Conclusion DUSP9 may improve hypercholesterolemia by up-regulating SREBP2 and LDL-r levels and decreased hepatic glucose output and fasted glucose levels by down-regulating the mRNA levels of PEPCK in high-fat diet induced insulin resistance C57 mice.