TNF-α impairs insulin signaling and insulin stimulation of glucose uptake in C2C12 muscle cells
TNF-α impairs insulin signaling and insulin stimulation of glucose uptake in C2C12 muscle cells
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DOI：
10.1152/ajpendo.1999.276.5.e849
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发表时间：
1999-05-01
影响因子：
5.1
通讯作者：
Kirwan, JP
中科院分区：
文献类型：
--
作者：
Del Aguila, LF;Claffey, KP;Kirwan, JP
生理应激源如败血症和组织损伤启动急性免疫反应并引起短暂的全身性胰岛素抵抗。本研究旨在确定肿瘤坏死因子-α（TNF-α），一种在骨骼肌损伤期间由免疫细胞产生的细胞因子，是否在细胞水平上降低胰岛素反应性。为了研究与TNF-α和胰岛素作用相关的分子机制，我们在培养的C2 C12肌管中测量了胰岛素受体底物（IRS）-1-和IRS-2-介导的磷脂酰肌醇3-激酶（PI 3-激酶）活化、IRS-1-PI 3-激酶结合、IRS-1酪氨酸磷酸化和两种促分裂原活化蛋白激酶（MAPK，称为p42（MAPK）和p44（MAPK））的磷酸化。此外，我们确定了TNF-α对胰岛素刺激的α-脱氧葡萄糖（2-DG）摄取的影响。我们观察到TNF-α分别使胰岛素刺激IRS-1和IRS-α介导的PIS-激酶活化减弱54%和55%（P < 0.05）。此外，TNF-α使胰岛素刺激的IRS-I酪氨酸磷酸化降低40%（P < 0.05）。此外，TNF-alpha还抑制了胰岛素诱导的p42（MAPK）和p44（MAPK）酪氨酸磷酸化81%（P < 0.01）。TNF-α对胰岛素信号激活的损害伴随着肌细胞中2-DG摄取的减少（P < 0.05）（60 +/- 4 vs. 44 +/- 6 pmol min（-1）mg（-1））。这些数据表明，TNF-α的增加可能通过抑制IRS-1和IRS-2介导的PI 3-激酶活化以及p42 MAPK和p44 MAPK酪氨酸磷酸化，导致胰岛素刺激的葡萄糖摄取受损，从而导致骨骼肌胰岛素抵抗。
Physiological stressors such as sepsis and tissue damage initiate an acute immune response and cause transient systemic insulin resistance. This study was conducted to determine whether tumor necrosis factor-alpha (TNF-alpha), a cytokine produced by immune cells during skeletal muscle damage, decreases insulin responsiveness at the cellular level. To examine the molecular mechanisms associated with TNF-alpha and insulin action, we measured insulin receptor substrate (IRS)-1- and IRS-2-mediated phosphatidylinositol 3-kinase (PI 3-kinase) activation, IRS-1-PI 3-kinase binding, IRS-1 tyrosine phosphorylation, and the phosphorylation of two mitogen-activated protein kinases (MAPK, known as p42(MAPK) and p44(MAPK)) in cultured C2C12 myotubes. Furthermore, we determined the effects of TNF-alpha on insulin-stimulated a-deoxyglucose (2-DG) uptake. We observed that TNF-alpha impaired insulin stimulation of IRS-1- and IRS-alpha-mediated PI S-kinase activation by 54 and 55% (P < 0.05), respectively. In addition, TNF-alpha decreased insulin-stimulated IRS-I tyrosine phosphorylation by 40% (P < 0.05). Furthermore, TNF-alpha repressed insulin-induced p42(MAPK) and p44(MAPK) tyrosine phosphorylation by 81% (P < 0.01). TNF-alpha impairment of insulin signaling activation was accompanied by a decrease (P < 0.05) in 2-DG uptake in the muscle cells (60 +/- 4 vs. 44 +/- 6 pmol min(-1) mg(-1)). These data suggest that increases in TNF-alpha may cause insulin resistance in skeletal muscle by inhibiting IRS-1- and IRS-2-mediated PI 3-kinase activation as well as p42MAPK and p44MAPK tyrosine phosphorylation, leading to impaired insulin-stimulated glucose uptake.