球形脂联素、葡萄糖和游离脂肪酸对胰岛β细胞单磷酸腺苷激活的蛋白激酶和乙酰辅酶A羧化酶磷酸化的影响

Effects of globular adiponectin,glucose and free fatty acid on AMPK and ACC phosphorylation in INS-1 β cells

目的:探讨不同浓度的葡萄糖和游离脂肪酸对胰岛β细胞内单磷酸腺苷激活的蛋白激酶(adenosine-5′-monophosphate activated prote in k inase,AMPK)和乙酰辅酶A羧化酶(acetyl CoA carboxylase,ACC)磷酸化的影响,以及球形脂联素对AMPK和ACC磷酸化的作用。方法:培养INS-1胰岛细胞系,用5 mmol/L葡萄糖和0.25 mmol/L游离脂肪酸处理,确定在不同时间对AMPK和ACC磷酸化的影响;观察不同浓度葡萄糖和游离脂肪酸对AMPK和ACC磷酸化的影响;在葡萄糖和游离脂肪酸存在的条件下观察AMPK的药理激活剂氨基咪唑-4甲-酰胺核苷酸(AICAR)和球形脂联素对AMPK和ACC磷酸化的影响。结果:不同浓度的葡萄糖和游离脂肪酸都能够在60 m in时抑制AMPK和ACC的磷酸化水平,采用AMPK的药理激动剂AICAR能够明显升高AMPK和ACC的磷酸化水平。2.5 mg/L球形脂联素可以使基础状态的AMPK和ACC磷酸化水平分别增加23%(P<0.05)和50%(P<0.05)。在5 mmol/L葡萄糖的基础上加用球形脂联素使AMPK和ACC磷酸化水平分别增加1.4倍(P<0.05)和3倍(P<0.01),在0.25 mmol/L游离脂肪酸的基础上加用球形脂联素使AMPK和ACC磷酸化水平分别增加3倍(P<0.05)和5倍(P<0.01)。结论:在体外培养的胰岛INS-1细胞中,不同浓度的葡萄糖和游离脂肪酸能够降低AMPK和ACC的磷酸化水平,而AMPK的药理激动剂氨基咪唑-4甲-酰胺核苷酸(5′-am inoim idazole-4-carboxam ideriboside,AICAR)和2.5 mg/L球形脂联素可以提高AMPK和ACC的磷酸化水平,此作用可以进一步增强胰岛β细胞内的脂肪酸氧化水平,减轻甘油三酯聚集,保护胰岛β细胞功能。

Objective： To investigate effects of glucose and free fatty acid at different concentrations on phosphorylation of adenosine-5＇-monophosphate activated protein kinase（AMPK） and acetyl CoA carboxylase （ACC） in INS-1 cells, and effects of globular adiponectin on phosphorylation of AMPK and ACC. Methods： INS-1 cells were cultured and treated with 5 mmol/L glucose or 0.25 mmol/L free fatty acids, and time courses and dose responses of different dosages of glucose and fatty acid on phosphorylation of AMPK and ACC were measured. We measured the effects of the pharmacological AMPK activator AICAR （5-aminoimidazole4-carboxamide-riboside） and globular adiponectin on phosphorylation of AMPK and ACC. Results： Glucose and fatty acid at different concentrations inhibited the phosphorylation of AMPK and ACC at the end of 60 min, but AICAR increased the phosphorylation of AMPK and ACC significantly, while 2.5 mg/L globular adiponectin increased the phosphorylation of AMPK and ACC by 23% （ P 〈 0.05 ） and 50% （P 〈 0.05 ） respectively, at baseline. In the presence of 5 mmol/L glucose, globular adiponectin increased AMPK and ACC phosphorylation by 1.4-fold （P 〈0.05 ） and 3-fold （P 〈0.01 ）, respectively. In the presence of 0.25 mmol/L free fatty acid, globular adiponectin increased AMPK and ACC phosphorylation 3-fold （ P 〈 0.05 ） and 5-fold （ P 〈 0.01 ） respectively. Conclusion ： In cultured islet cells, glucose and free fatty acid at various concentrations inhibit the phosphorylation of AMPK and ACC, but AICAR and globular adiponectin 2.5 mg/L increase the phosphorylation level. This may constitute a mechanism to increase fatty acid oxidation and decrease triglyceride accumulation in islet β cells.