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目的研究胰岛素对骨骼肌细胞固醇调节原件结合蛋白1c(SREBP-1c)的调节作用。方法将诱导分化完成的大鼠骨骼肌L6肌管细胞分为对照组、胰岛素组、磷酸酰基醇3激酶抑制剂wortmannin+胰岛素组、单磷酸腺苷依赖的蛋白激酶(AMPK)抑制剂compound C+胰岛素组、高脂对照组、高脂+胰岛素组、高脂+wortmannin+胰岛素组和高脂+compound C+胰岛素组。Western blot检测SREBP-1c、苏氨酸蛋白激酶(Akt)-哺乳动物雷帕霉素靶蛋白(mTOR)、AMPK-mTOR通路相关蛋白的表达。结果与对照组相比,胰岛素组SREBP-1c、p-Akt、p-AMPK、p-mTOR蛋白表达升高(P<0.05);与胰岛素组相比,wortmannin+胰岛素组SREBP-1c表达降低(P<0.05);与高脂对照组相比,高脂+胰岛素组SREBP-1c、p-mTOR蛋白表达降低,p-Akt、p-AMPK蛋白表达升高(P<0.05);与高脂+胰岛素组相比,高脂+compound C+胰岛素组SREBP-1c表达升高(P<0.05)。结论骨骼肌细胞生理状态下,胰岛素对SREBP-1c的上调作用可能主要通过Akt-mTOR通路;胰岛素抵抗状态下,胰岛素治疗对SREBP-1c的下调作用可能主要通过AMPK-mTOR通路。
Objective To investigate the regulatory effect of insulin on skeletal muscle cells sterol regulatory element binding protein 1c (SREBP-1c). Methods L6 myotubes of rat skeletal muscle induced by differentiation were divided into control group, insulin group, wortmannin + insulin group, phosphate AMPK inhibitor compound C + insulin group , High fat control group, high fat + insulin group, high fat + wortmannin + insulin group and high fat + compound C + insulin group. Western blot was used to detect the expression of SREBP-1c and the protein of threonine kinase (Akt) - mammalian target of rapamycin (mTOR) and AMPK-mTOR pathway. Results Compared with the control group, the expression of SREBP-1c, p-Akt, p-AMPK and p-mTOR in the insulin group was significantly higher than that in the control group (P <0.05). Compared with the high fat control group, the expression of SREBP-1c and p-mTOR protein and the expression of p-Akt and p-AMPK in high fat + insulin group were significantly increased Compared with the control group, the expression of SREBP-1c was increased in the hyperlipidemia + compound C + insulin group (P <0.05). Conclusion Upregulation of SREBP-1c by insulin may be mainly through the Akt-mTOR pathway in skeletal muscle cells. Down-regulation of SREBP-1c by insulin therapy may be mainly through the AMPK-mTOR pathway in insulin resistance state.