南方医科大学学报

南方医科大学学报 ›› 2022, Vol. 42 ›› Issue (3): 392-398.doi: 10.12122/j.issn.1673-4254.2022.03.11

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CD36基因缺失通过上调PTP1B基因表达降低小鼠肌肉胰岛素敏感性

陈 琳，曾 晗，秦 虹，阮雄中，杨 萍   

  1. 重庆医科大学脂糖代谢性疾病重庆市重点实验室，重庆 400016
  • 出版日期:2022-03-20 发布日期:2022-04-11

CD36 gene deletion reduces muscle insulin sensitivity in mice by up-regulating PTP1B expression

CHEN Lin, ZENG Han, QIN Hong, RUAN Xiongzhong, YANG Ping   

  1. Chongqing Key Laboratory of Lipid and Glucose Metabolism, Center for Lipid Research, Chongqing Medical University, Chongqing 400016, China
  • Online:2022-03-20 Published:2022-04-11

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摘要： 目的 探讨在正常饮食状态下，CD36基因缺失对小鼠肌肉胰岛素信号通路的影响及作用机制。方法 野生型小鼠（WT）和CD36基因敲除小鼠（CD36-/-）给予正常饮食喂养14周（n=12）。小鼠禁食4 h，腹腔注射胰岛素（1 U/kg）进行胰岛素耐量实验。Real-time PCR检测小鼠肌肉胰岛素受体(IR)、胰岛素受体底物1/2（IRS1/2）、蛋白酪氨酸磷酸酶1B（PTP1B）基因表达。Western blot检测小鼠肌肉蛋白激酶B(AKT)、IR、IRS1/2和PTP1B的蛋白表达。免疫共沉淀（Co-IP）检测肌肉IR和IRS1的酪氨酸磷酸化程度。染色质免疫共沉淀（ChIP）技术检测肌肉PTP1B启动子组蛋白乙酰化水平。结果 在正常饮食状态下，与WT小鼠相比，CD36-/-小鼠的胰岛素耐量显著增强（P<0.05），血清胰岛素浓度升高（P<0.01），胰岛素抵抗指数(HOMA-IR)升高（P<0.05）。在肌肉组织中，CD36-/-小鼠与WT小鼠相比，p-AKT/AKT蛋白表达比值显著降低（P<0.01）。Real-time PCR和Western blot结果表明，肌肉组织IR，IRS1，IRS2的mRNA和蛋白水平在WT和CD36-/-小鼠间无显著差异（P>0.05）。Co-IP实验显示IR和IRS1的酪氨酸磷酸化水平在CD36-/-小鼠中显著降低（P<0.05）。CD36-/-小鼠肌肉中PTP1B mRNA和蛋白表达均高于WT小鼠（P<0.05），ChIP实验显示PTP1B基因启动子的组蛋白乙酰化水平显著升高（P<0.01）。腹腔注射PTP1B的抑制剂可改善CD36-/-小鼠的胰岛素敏感性。结论 在正常饮食条件下，CD36基因对于维持生理肌肉胰岛素敏感性十分重要，小鼠CD36基因缺失通过上调PTP1B基因表达，诱导IR、IRS1去酪氨酸磷酸化而使肌肉胰岛素信号传导受损。

关键词: CD36；胰岛素敏感性；肌肉；PTP1B

Abstract: Objective To investigate the effect CD36 deficiency on muscle insulin signaling in mice fed a normal-fat diet and explore the possible mechanism. Methods Wild-type (WT) mice and systemic CD36 knockout (CD36-/- ) mice with normal feeding for 14 weeks (n=12) were subjected to insulin tolerance test (ITT) after intraperitoneal injection with insulin (1 U/kg). Real-time PCR was used to detect the mRNA expressions of insulin receptor (IR), insulin receptor substrate 1/2 (IRS1/2) and protein tyrosine phosphatase 1B (PTP1B), and Western blotting was performed to detect the protein expressions of AKT, IR, IRS1/2 and PTP1B in the muscle tissues of the mice. Tyrosine phosphorylation of IR and IRS1 and histone acetylation of PTP1B promoter in muscle tissues were detected using co-immunoprecipitation (Co-IP) and chromatin immunoprecipitation (ChIP), respectively. Results CD36-/- mice showed significantly lowered insulin sensitivity with obviously decreased area under the insulin tolerance curve in comparison with the WT mice (P<0.05). CD36-/- mice also had significantly higher serum insulin concentration and HOMA-IR than WT mice (P<0.05). Western blotting showed that the p-AKT/AKT ratio in the muscle tissues was significantly decreased in CD36-/- mice as compared with the WT mice (P<0.01). No significant differences were found in mRNA and protein levels of IR, IRS1 and IRS2 in the muscle tissues between WT and CD36-/- mice (P>0.05). In the muscle tissue of CD36-/- mice, tyrosine phosphorylation levels of IR and IRS1 were significantly decreased (P<0.05), and the mRNA and protein levels of PTP1B (P<0.05) and histone acetylation level of PTP1B promoters (P<0.01) were significantly increased as compared with those in the WT mice. Intraperitoneal injection of claramine, a PTP1B inhibitor, effectively improved the impairment of insulin sensitivity in CD36-/- mice. Conclusion CD36 is essential for maintaining muscle insulin sensitivity under physiological conditions, and CD36 gene deletion in mice causes impaired insulin sensitivity by up-regulating muscle PTP1B expression, which results in detyrosine phosphorylation of IR and IRS1.

Key words: CD36; insulin sensitivity; muscle; PTP1B