Deletion of exon 21 of the insulin receptor eliminates tyrosine kinase activity but preserves mitogenic signaling.
Deletion of exon 21 of the insulin receptor eliminates tyrosine kinase activity but preserves mitogenic signaling.
复制标题
删除胰岛素受体的外显子 21 可消除酪氨酸激酶活性，但保留促有丝分裂信号传导。
DOI：
10.1021/bi00212a021
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发表时间：
1993
期刊：
影响因子：
2.9
通讯作者：
Olefsky,JM
中科院分区：
文献类型：
--
作者：
Rolband,GC;Williams,JF;Webster,NJ;Hsu,D;Olefsky,JM
1993年9月14日收到的修订手稿®摘要：为了研究胰岛素受体21号外显子的功能，构建了缺乏该结构域的突变型人胰岛素受体。将突变体HIRAE 21 cDNA转染大鼠1号成纤维细胞，筛选稳定的细胞系。HIRAE 21受体在细胞表面表达，它们与胰岛素结合的亲和力与野生型表达细胞系hIRcB相同。HIRAE 21受体未显示出可检测的自磷酸化或激酶活性，正如预期的那样，内化受损，代谢信号传导特性缺失。出乎意料的是，胰岛素刺激表达HIRAE 21受体的细胞中DNA合成的能力远远大于亲本Rat-1细胞中的能力，并且与hIRcB细胞系中测量的能力相等。通过显示用人类特异性胰岛素模拟抗胰岛素受体抗体处理HIRAE 21细胞也导致DNA合成增强，证实了HIR AE 21受体的促有丝分裂信号传导特性增强。因此，尽管在HIRAE 21细胞中没有检测到胰岛素受体自磷酸化或激酶活性，但这些细胞显示出增强的胰岛素诱导的促有丝分裂信号传导。这些结果表明，胰岛素的长期生物学效应存在另一条非激酶依赖的刺激-应答途径，胰岛素受体（IR）是由两个α亚基和两个β亚基组成的异源四聚体跨膜糖蛋白。细胞外结构域含有胰岛素结合位点，受体的细胞质区含有酪氨酸激酶结构域。在胰岛素与IR结合后，发生构象变化，导致酪氨酸残基的自磷酸化（Kasuga等人，1982;罗森埃塔尔，1983; Yu & Czech，1984）和酪氨酸激酶活性的激活。然后，活化的受体可以与内源性底物结合并磷酸化内源性底物，例如ppl 85/IRS-I（Maegawa et al. 1998 a; Olefsky，1990;罗森，1987; Whitetal.，1985年）。这种酪氨酸激酶活性是胰岛素作用级联中最早的步骤之一，并且存在许多证据表明它对于大多数（如果不是全部）胰岛素的生物学效应是必需的（Cadena & Gill，1992; Maegawa et al. 1998 a; Olefsky，1990;罗森，1987;白色等人，1985年）。
Revised Manuscript Received September 14, 1993® abstract: To study the function of exon 21 of the insulin receptor, a mutant humaninsulin receptor lacking this domain was constructed. The mutant HIRAE21 cDNA was transfected into Rat-1 Fibroblasts and stable cell lines were selected. The HIRAE21 receptors were expressed on the cell surface, and they bound insulin with the same affinity as did the wild-type-expressing cell line, hIRcB. The HIRAE21 receptors did not display detectable autophosphorylation or kinase activity, and as expected, internalization was impaired and metabolic signaling properties were absent. Unexpectedly, insulin’s ability to stimulate DNA synthesis in cells expressing HIRAE21 receptors was far greater than that in the parental Rat-1 cells and equal to that measured in the hIRcB cell line. The enhanced mitogenic signaling properties of the HIR AE21 receptors was confirmed by showing that treatment of HIRAE21 cells with a human-specific insulin-mimetic anti-insulin receptor antibody also led to enhanced DNA synthesis. Thus, although no insulin receptor autophosphorylation or kinase activity was detectable in HIRAE21 cells, these cells displayed enhanced insulin-induced mitogenic signaling. These results suggest that an alternative non-kinase-dependent stimulus-response pathway exists for the long-term biological effects of insulin.The insulin receptor (IR) is a heterotetrameric transmembrane glycoprotein consisting of two a and two (3 subunits. The extracellular domain contains the insulin binding site (s) and the cytoplasmic region of the receptor contains the tyrosine kinase domain. After insulin binds to the IR a conformational change occurs, leading to autophosphorylation of tyrosine residues (Kasuga et al., 1982; Rosen etal., 1983; Yu & Czech, 1984) and activation of tyrosinekinase activity. The activated receptor can then associate with and phosphorylate endogenous substrates, such as ppl85/IRS-I (Maegawa et al., 1998a; Olefsky, 1990; Rosen, 1987; Whiteetal., 1985). This tyrosine kinase activity is one of the earliest steps in the insulin action cascade, and much evidence exists indicating that it is essential for most, if not all, of insulin’s biological effects (Cadena & Gill, 1992; Maegawa et al., 1998a; Olefsky, 1990; Rosen, 1987; White et al., 1985).