Deletion of the pleckstrin and phosphotyrosine binding domains of insulin receptor substrate-2 does not impair its ability to regulate cell proliferation in myeloid cells.
Deletion of the pleckstrin and phosphotyrosine binding domains of insulin receptor substrate-2 does not impair its ability to regulate cell proliferation in myeloid cells.
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DOI：
10.1210/en.2004-0668
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发表时间：
2004-11
期刊：
影响因子：
4.8
通讯作者：
Hongzhi Sun;R. Baserga
中科院分区：
文献类型：
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作者：
Hongzhi Sun;R. Baserga
32 D IGF-I受体（IR）细胞是IL-3依赖性骨髓细胞，可被IGF-I诱导分化为粒细胞。与亲本32 D细胞一样，32 D IGF-IR细胞不表达胰岛素受体底物（IRS）-1或IRS-2。我们研究了IRS-2在32 D IGF-IR细胞中异位表达的影响。这些细胞中野生型IRS-2的表达抑制IGF-I诱导的分化，并且细胞在缺乏IL-3的情况下无限期生长。我们还研究了缺乏pleckstrin（PH）和磷酸酪氨酸结合（PTB）结构域的突变IRS-2的作用，这些结构域已知与IR结合。偏微分PHPTB IRS-2完全能够与野生型IRS-2（和野生型IRS-1）一样刺激32 D IGF-IR细胞的生长并抑制其分化。相比之下，IRS-1蛋白缺乏相同的PH和PTB结构域是完全无活性的阻断分化和刺激IL-3非依赖性生长的32 D IGF-IR细胞。部分分化PHPTB IRS-2蛋白依赖于其对活化的IGF-IR的作用，是细胞质的，与IGF-IR的β-亚基结合，并且其作用需要磷脂酰肌醇3-激酶结合序列的存在。这些实验表明IRS-2的PH和PTB结构域（而不是IRS-1）对于IGF-I/IRS-2介导的32 D骨髓细胞的生长是不稳定的。我们的结果还表明IRS-2（野生型或部分分化PHPTB）能够抑制32 D细胞的分化。
32D IGF-I receptor (IR) cells are IL-3-dependent myeloid cells that can be induced to differentiate into granulocytes by IGF-I. Like the parental 32D cells, 32D IGF-IR cells do not express the insulin receptor substrate (IRS)-1 or IRS-2. We investigated the effect of ectopic expression of IRS-2 in 32D IGF-IR cells. Expression in these cells of a wild-type IRS-2 inhibits IGF-I-induced differentiation, and the cells grow indefinitely in the absence of IL-3. We also investigated the effect of a mutant IRS-2 lacking both the pleckstrin (PH) and the phosphotyrosine-binding (PTB) domains, which are known to bind to the IR. The partial differentialPHPTB IRS-2 is fully as capable as the wild-type IRS-2 (and wild-type IRS-1) to stimulate the growth and inhibit the differentiation of 32D IGF-IR cells. In contrast, an IRS-1 protein lacking the same PH and PTB domains is completely inactive in blocking differentiation and stimulating IL-3-independent growth of 32D IGF-IR cells. The partial differentialPHPTB IRS-2 protein is dependent for its effect on an activated IGF-IR, is cytoplasmic, binds to the beta-subunit of the IGF-IR, and requires for its action the presence of phosphatidylinositol 3-kinase binding sequences. These experiments show that the PH and PTB domains of IRS-2 (but not IRS-1) are dispensable for the IGF-I/IRS-2-mediated growth of 32D myeloid cells. Our results also indicate that IRS-2 (either wild type or partial differentialPHPTB) is capable of inhibiting the differentiation of 32D cells.