Phosphorylation of insulin receptor substrate-1 on multiple serine residues, 612, 632, 662, and 731, modulates insulin action
Phosphorylation of insulin receptor substrate-1 on multiple serine residues, 612, 632, 662, and 731, modulates insulin action
复制标题
DOI：
10.1074/jbc.271.19.11222
复制
发表时间：
1996-05-10
影响因子：
4.8
通讯作者：
VanObberghen, E
中科院分区：
文献类型：
--
作者：
Mothe, I;VanObberghen, E
冈田酸先前被描述为胰岛素信号传导的负调节剂，因为它抑制胰岛素对葡萄糖转运的刺激。此外，该药物还可诱导胰岛素受体底物 1 (IRS-1) 酪氨酸磷酸化减少，同时丝氨酸/苏氨酸磷酸化增加。目前的工作旨在鉴定丝氨酸/苏氨酸残基，这些残基在磷酸化后可能参与调节胰岛素信号传导。为此，我们研究了IRS-1的双点突变体，其中丝氨酸612/632和662/731被丙氨酸取代。这些是丝裂原激活蛋白激酶磷酸化的四个可能位点，并且紧邻酪氨酸残基，这些残基是与磷脂酰肌醇 3-激酶 Src 同源 2 结构域相互作用的潜在位点。使用 293 EBNA 细胞中的瞬时表达，我们证明丝氨酸 612、632、662 和 731 以及丝裂原激活蛋白激酶不参与冈田酸对 IRS-1 的作用。相反，这些丝氨酸似乎在调节基础和胰岛素刺激的IRS-1酪氨酸磷酸化、IRS-1与p85的关联以及IRS-1中的磷脂酰肌醇3激酶活性中发挥作用。 p85 免疫复合物，因为这些位点的突变会增强这些事件。我们的研究结果表明，IRS-1 脱敏机制的存在是由丝氨酸/苏氨酸磷酸化引起的，至少发生在丝氨酸 612、632、662 和 731 上。
Okadaic acid has been described previously as being a negative regulator of insulin signaling, as it inhibits insulin stimulation of glucose transport. In addition, this drug induces on insulin receptor substrate-1 (IRS-1) a decrease in tyrosine phosphorylation, concomitantly with an increase in serine/threonine phosphorylation. The present work was aimed at the identification of the serine/threonine residues that, upon phosphorylation, might be involved in modulating insulin signaling. To this end, we studied double-point mutants of IRS-1, in which serines 612/632 and 662/731 were replaced with alanine. These are four plausible sites of phosphorylation by mitogen-activated protein kinases and are in the immediate proximity of tyrosine residues, which are potential sites of interaction with the phosphatidylinositol 3-kinase Src homology 2 domains. Using transient expression in 293 EBNA cells, we demonstrate that serines 612, 632, 662, and 731 and mitogen-activated protein kinases are not involved in the okadaic acid effect on IRS-1. Rather, these serines appear to play a role in modulating basal and insulin-stimulated IRS-1 tyrosine phosphorylation, association of IRS-1 with p85, and phosphatidylinositol 3-kinase activity in the IRS-1 . p85 immune complex, since mutation of these sites enhances these events. Our findings suggest the existence of an IRS-1 desensitization mechanism resulting from serine/threonine phosphorylation, occurring at least on serines 612, 632, 662, and 731.