Nutrient-dependent and insulin-stimulated phosphorylation of insulin receptor substrate-1 on serine 302 correlates with increased insulin signaling
Nutrient-dependent and insulin-stimulated phosphorylation of insulin receptor substrate-1 on serine 302 correlates with increased insulin signaling
复制标题
DOI：
10.1074/jbc.m308631200
复制
发表时间：
2004-01-30
影响因子：
4.8
通讯作者：
White, MF
中科院分区：
文献类型：
--
作者：
Giraud, J;Leshan, R;White, MF
胰岛素受体底物IRS-1的Ser/Thr磷酸化调控胰岛素信号转导，但相关的磷酸化残基及其在胰岛素刺激信号转导中的潜在功能尚不清楚。我们使用针对磷酸化Ser（302）的序列特异性多克隆抗体来研究胰岛素和胰岛素样生长因子IGF-I刺激期间IRS-1介导的信号传导。胰岛素或IGF-I刺激各种细胞背景和小鼠肌肉中Ser（302）的磷酸化。渥曼青霉素或雷帕霉素抑制Ser（302）磷酸化，氨基酸或葡萄糖刺激Ser（302）磷酸化，表明mTOR级联的作用。Ser（302）激酶在免疫沉淀过程中与IRS-1结合，但其身份尚不清楚。NH 2-末端c-Jun激酶不磷酸化Ser（302）。用丙氨酸取代Ser（302）显著降低胰岛素刺激的IRS-1和p85结合的酪氨酸磷酸化，并降低胰岛素刺激的p70（S6 K）、核糖体S6蛋白和4 E-BP 1的磷酸化;然而，该突变对胰岛素刺激的Akt或糖原合成酶激酶3 β磷酸化没有影响。用丙氨酸替代Ser（302）减少胰岛素/IGF-I刺激的DNA合成。我们的结论是，丝氨酸（302）磷酸化整合营养供应与胰岛素/IGF-I信号，以促进有丝分裂和细胞生长。
Ser/Thr phosphorylation of insulin receptor substrate IRS-1 regulates insulin signaling, but the relevant phosphorylated residues and their potential functions during insulin-stimulated signal transduction are difficult to resolve. We used a sequence-specific polyclonal antibody directed against phosphorylated Ser(302) to study IRS-1-mediated signaling during insulin and insulin-like growth factor IGF-I stimulation. Insulin or IGF-I stimulated phosphorylation of Ser(302) in various cell backgrounds and in murine muscle. Wortmannin or rapamycin inhibited Ser(302) phosphorylation, and amino acids or glucose stimulated Ser(302) phosphorylation, suggesting a role for the mTOR cascade. The Ser(302) kinase associates with IRS-1 during immunoprecipitation, but its identity is unknown. The NH2-terminal c-Jun kinase did not phosphorylate Ser(302). Replacing Ser(302) with alanine significantly reduced insulin-stimulated tyrosine phosphorylation of IRS-1 and p85 binding and reduced insulin-stimulated phosphorylation of p70(S6K), ribosomal S6 protein, and 4E-BP1; however, this mutation had no effect on insulin-stimulated Akt or glycogen synthase kinase 3beta phosphorylation. Replacing Ser(302) with alanine reduced insulin/IGF-I-stimulated DNA synthesis. We conclude that Ser(302) phosphorylation integrates nutrient availability with insulin/IGF-I signaling to promote mitogenesis and cell growth.