Role of IRS and PHIP on insulin-induced tyrosine phosphorylation and distribution of IRS proteins
Role of IRS and PHIP on insulin-induced tyrosine phosphorylation and distribution of IRS proteins
复制标题
DOI：
10.1247/csf.07003
复制
发表时间：
2007-01-01
影响因子：
1.5
通讯作者：
Noda, Mitsuhiko
中科院分区：
文献类型：
--
作者：
Kaburagi, Yasushi;Okochi, Hitoshi;Noda, Mitsuhiko
为了分析胰岛素受体底物（IRS）家族的功能差异，在Cos- 1细胞中表达了IRS蛋白的N-末端含有普列克底物蛋白同源（PH）结构域和磷酸酪氨酸结合（PTB）结构域的片段（IRS-N）以及完整的IRS分子，并分析了胰岛素诱导的IRS蛋白酪氨酸磷酸化和亚细胞分布.与对磷酸肌醇的独特亲和力相反，这些IRS- N片段非选择性地抑制胰岛素诱导的IRS- 1、IRS- 2和IRS- 3的酪氨酸磷酸化，其中IRS-3- N最有效。IRS- 1的突变破坏PH和PTB结构域中的所有磷酸肌醇结合位点，显著但不完全抑制IRS- 1的酪氨酸磷酸化，这被检测的所有IRS- N蛋白的共表达进一步抑制.相反，PH-相互作用蛋白（PHIP）的N-末端PH结构域相互作用区（PHIP-N）不损害任一IRS分子的酪氨酸磷酸化.使用共聚焦显微镜的分析还表明，所有的IRS-N蛋白，但不是PHIP-N，抑制IRS- 1靶向质膜响应胰岛素。此外，IRS- 1的磷酸肌醇亲和力破坏突变显著削弱但不能完全消除胰岛素诱导的IRS- 1向质膜的移位，这被IRS-1- N过表达进一步抑制.这些发现表明胰岛素诱导的酪氨酸磷酸化和IRS蛋白的细胞表面靶向可以通过IRS家族成员共有的靶分子以类似的方式调节，并且不同于磷酸肌醇或PHIP。
To analyze the functional differences of the insulin receptor substrate ( IRS) family, the N- terminal fragments containing the pleckstrin homology ( PH) domains and the phosphotyrosine- binding ( PTB) domains of IRS ( IRS- N) proteins, as well as intact IRS molecules, were expressed in Cos- 1 cells, and insulin- induced tyrosine phosphorylation and subcellular distribution of IRS proteins were analyzed. In contrast to the distinct affinities toward phosphoinositides, these IRS- N fragments non- selectively inhibited insulin- induced tyrosine phosphorylation of IRS- 1, IRS- 2 and IRS- 3, among which IRS3- N was most effective. The mutations of IRS- 1 disrupting all the phosphoinositide- binding sites in both the PH and PTB domains significantly but not completely suppressed tyrosine phosphorylation of IRS- 1, which was further inhibited by coexpression of all the IRS- N proteins examined. In contrast, the N- terminal PH domain- interacting region ( PHIP- N) of PH- interacting protein ( PHIP) did not impair tyrosine phosphorylation of either IRS molecule. The analysis using confocal microscopy also demonstrated that all the IRS- N proteins, but not PHIP- N, suppressed targeting of IRS- 1 to the plasma membrane in response to insulin. Moreover, the phosphoinositide affinity- disrupting mutations of IRS- 1 significantly impaired but did not completely abrogate the insulin- induced translocation of IRS- 1 to the plasma membrane, which was further suppressed by IRS1- N overexpression. These findings suggest that both insulin- induced tyrosine phosphorylation and the cell surface targeting of IRS proteins may be regulated in a similar manner through a target molecule common to the members of the IRS family, and distinct from phosphoinositides or PHIP.