Improved insulin sensitivity by calorie restriction is associated with reduction of ERK and p70S6K activities in the liver of obese Zucker rats.
Improved insulin sensitivity by calorie restriction is associated with reduction of ERK and p70S6K activities in the liver of obese Zucker rats.
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DOI：
10.1677/joe-09-0181
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发表时间：
2009-12
期刊：
影响因子：
--
通讯作者：
Sun XJ
中科院分区：
文献类型：
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作者：
Zheng Y;Zhang W;Pendleton E;Leng S;Wu J;Chen R;Sun XJ
热量限制（CR）通过未明确的分子机制改善肥胖相关的胰岛素抵抗。胰岛素受体底物 (IRS)-1 丝氨酸/苏氨酸激酶已被提议通过 IRS 蛋白的磷酸化来调节胰岛素敏感性。本研究的目的是检验以下假设：IRS1 丝氨酸/苏氨酸激酶活性的变化可能是 CR 改善胰岛素敏感性的分子机制的基础。肥胖和瘦的 Zucker 大鼠接受 40% CR 或允许自由采食 (AL) 20 周；在此期间监测体重和胰岛素敏感性。使用各种谷胱甘肽-S-转移酶进行体外激酶测定，测量肝组织提取物中IRS1丝氨酸/苏氨酸激酶的活性，包括JNK、ERK、MTOR/p70S6K（MGI数据库中列出的RPS6KB1）、糖原合酶激酶3β（GSK3B）、AMPK（MGI数据库中列出的PRKAA1）和蛋白激酶Cθ（PRKCQ） (GST)–IRS1 片段作为底物，而 IRS1 和丝氨酸激酶的磷酸化则使用磷酸特异性抗体通过蛋白质印迹法测定。与 AL 对照组相比，肥胖大鼠的 CR 显着降低了体重并增加了胰岛素敏感性。与瘦同窝小鼠相比，肥胖大鼠对 IRS1S612（对应于人 IRS1 中的 S616）和 IRS1S632/635（对应于人 IRS1 中的 S636/639）的丝氨酸激酶活性增加，并且在 CR 后显着降低。与此同时，肥胖增加，CR 降低了肝脏 ERK 和 p70S6K 对抗 IRS1 的活性。肝脏 ERK 和 p70S6K 的活性与胰岛素抵抗之间的密切关联表明，ERK 和 p70S6K 在胰岛素抵抗的发展中发挥着重要作用，可能是通过 IRS 蛋白的磷酸化实现的。
Calorie restriction (CR) improves obesity-related insulin resistance through undefined molecular mechanisms. Insulin receptor substrate (IRS)-1 serine/threonine kinases have been proposed to modulate insulin sensitivity through phosphorylation of IRS proteins. The aim of this study is to test the hypothesis that changes in the activity of IRS1 serine/threonine kinases may underlie the molecular mechanism of CR in improving insulin sensitivity. Obese and lean Zucker rats were subjected to 40% CR or allowed to feed ad libitum (AL) for 20 weeks; body weight and insulin sensitivity were monitored throughout this period. The activity of IRS1 serine/threonine kinases – including JNK, ERK, MTOR/p70S6K (RPS6KB1 as listed in the MGI Database), glycogen synthase kinase 3β (GSK3B), AMPK (PRKAA1 as listed in the MGI Database), and protein kinase Cθ (PRKCQ) in liver tissue extracts was measured by an in vitro kinase assay using various glutathione-S-transferase (GST)–IRS1 fragments as substrates, while phosphorylation of IRS1 and serine kinases was determined by western blotting using phosphospecific antibodies. CR in obese rats significantly reduced body weight and increased insulin sensitivity compared to AL controls. Serine kinase activity toward IRS1S612 (corresponding to S616 in human IRS1) and IRS1S632/635 (corresponding to S636/639 in human IRS1) was increased in obese rats compared to lean littermates, and was markedly decreased following CR. Concomitantly, obesity increased and CR decreased the activity of hepatic ERK and p70S6K against IRS1. The close association between the activity of hepatic ERK and p70S6K with insulin resistance suggests an important role for ERK and p70S6K in the development of insulin resistance, presumably via phosphorylation of IRS proteins.