Molecular cloning of rat SH2-containing inositol phosphatase 2 (SHIP2) and its role in the regulation of insulin signaling
Molecular cloning of rat SH2-containing inositol phosphatase 2 (SHIP2) and its role in the regulation of insulin signaling
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DOI：
10.1006/bbrc.1999.0888
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发表时间：
1999-06-24
影响因子：
3.1
通讯作者：
Kobayashi, M
中科院分区：
文献类型：
--
作者：
Ishihara, H;Sasaoka, T;Kobayashi, M
SH2-containing inositol 5'-phosphatase （SHIP）在造血细胞中起负调控作用。我们从大鼠骨骼肌中克隆了SHIP同工酶（SHIP2） cDNA，而骨骼肌是胰岛素作用最重要的靶组织之一。大鼠SHIP cDNA编码一个1183个氨基酸的蛋白，与大鼠SHIP有45%的同源性。大鼠SHIPS包含一个氨基末端SH2结构域、一个中央5'-磷酸肌醇磷酸酶活性结构域、一个磷酸酪氨酸结合（PTB）一致序列和一个羧基尾部富含脯氨酸的区域。通过在表达人胰岛素受体（HIRc）的Rat1成纤维细胞中稳定过表达大鼠SHIPS，研究了SHIPS的特异性抗体。内源性SHIPS经历胰岛素介导的酪氨酸磷酸化，当SHIPS过表达时磷酸化显著增加。虽然过表达SHIPS并不影响胰岛素诱导的胰岛素受体p亚基和Shc的酪氨酸磷酸化，但随后Shc与Grb2的关联被抑制，可能是由于SHIPS和Grb2的SH2结构域对Shc磷酸酪氨酸的竞争。结果，在ship2过表达的细胞中，胰岛素刺激的MAP激酶激活减少。胰岛素诱导的IRS-1酪氨酸磷酸化、IRS-1与pi3激酶p85亚基的关联以及pi3激酶的激活均不受SHIPS过表达的影响。有趣的是，尽管PtdIns-(3,4,5)P3和PtdIns(3,4)P2在体外都参与了Akt活性的调节，但hips的过表达抑制了胰岛素诱导的Akt活化，可能是通过其5'-肌醇磷酸酶活性。此外，胰岛素诱导的胸腺嘧啶掺入通过过表达SHIPS减少。这些结果表明，SHIPS在胰岛素诱导的有丝分裂发生中发挥负调控作用，而Shc Grb2复合物和pi3激酶下游产物的调控可能提供了SHIPS在胰岛素信号传导中的作用机制。(C) 1999学术出版社。
SH2-containing inositol 5'-phosphatase (SHIP) plays a negative regulatory role in hematopoietic cells. We have now cloned the rat SHIP isozyme (SHIP2) cDNA from skeletal muscle, which is one of the most important target tissue of insulin action. Rat SHIPS cDNA encodes a 1183-amino-acid protein that is 45% identical with rat SHIP. Rat SHIPS contains an aminoterminal SH2 domain, a central 5'-phosphoinositol phosphatase activity domain, and a phosphotyrosine binding (PTB) consensus sequence and a proline-rich region at the carboxyl tail. Specific antibodies to SHIPS were raised and the function of SHIPS was studied by stably overexpressing rat SHIPS in Rat1 fibroblasts expressing human insulin receptors (HIRc). Endogenous SHIPS underwent insulin-mediated tyrosine phosphorylation and phosphorylation was markedly increased when SHIPS was overexpressed. Although overexpression of SHIPS did not affect insulin-induced tyrosine phosphorylation of the insulin receptor P-subunit and Shc, subsequent association of Shc with Grb2 was inhibited, possibly by competition between the SH2 domains of SHIPS and Grb2 for the Shc phosphotyrosine. As a result, insulin-stimulated MAP kinase activation was reduced in SHIP2-over-expressing cells. Insulin-induced tyrosine phosphorylation of IRS-1, IRS-1 association with the p85 subunit of PI3-kinase, and PI3-kinase activation were not affected by overexpression of SHIPS. Interestingly, although both PtdIns-(3,4,5)P3 and PtdIns(3,4)P2 have been implicated in the regulation of Akt activity in vitro, overexpression of SHIPS inhibited insulin-induced Akt activation, presumably by its 5'-inositol phosphatase activity. Furthermore, insulin-induced thymidine incorporation was decreased by overexpression of SHIPS. These results indicate that SHIPS plays a negative regulatory role in insulin-induced mitogenesis, and regulation of the Shc Grb2 complex and of the downstream products of PI3-kinase provides possible mechanisms of SHIPS action in insulin signaling. (C) 1999 Academic Press.