INSULIN AND INSULIN-LIKE GROWTH-FACTOR-I RECEPTORS SIMILARLY STIMULATE DEOXYRIBONUCLEIC-ACID SYNTHESIS DESPITE DIFFERENCES IN CELLULAR PROTEIN-TYROSINE PHOSPHORYLATION

被引:46
作者
MASTICK, CC
KATO, H
ROBERTS, CT
LEROITH, D
SALTIEL, AR
机构
[1] WARNER LAMBERT PARKE DAVIS, PARKE DAVIS PHARMACEUT RES DIV, ANN ARBOR, MI 48105 USA
[2] NIDDK, DIABET BRANCH, BETHESDA, MD 20892 USA
[3] UNIV MICHIGAN, SCH MED, DEPT PHYSIOL, ANN ARBOR, MI 48109 USA
关键词
D O I
10.1210/en.135.1.214
中图分类号
R5 [内科学];
学科分类号
1002 ; 100201 ;
摘要
Signal transduction pathways stimulated by insulin or insulin-like growth factor-I (IGF-I) were compared in transfected NIH3T3 fibroblast cell lines expressing the human insulin receptor, IGF-I receptor, or a chimeric IGF-I receptor with its carboxy-terminal tail replaced with that of the insulin receptor (-1 X 10(6) receptors/cell). Although receptor autophosphorylation was very similar in the three cell lines overexpressing receptors (EC(50) = 1-3 nM), there were differences detected in the protein tyrosine phosphorylation stimulated by insulin and IGF-I in these cells. Although no substrates specific for the insulin receptor were detected, phosphorylation of a 170-kilodalton (kDa; IRS1) and a 70-kDa protein was 10 times more sensitive to insulin than to IGF-I (EC(50) = 1.5-2.5 us. 14-23 nM). The chimeric receptor stimulated significantly lower levels of phosphorylation of several proteins relative to the wild-type IGF-I receptor. Activation of phosphatidylinositol 3 '-kinase paralleled phosphorylation of the 170- and 70-kDa proteins. Despite these differences in protein tyrosine phosphorylation, stimulation of mitogen-activated protein (MAP) kinase and DNA synthesis were very similar in the three cell lines overexpressing receptors. Little difference was detected in She phosphorylation or MAP kinase activation through the three receptors, although activation of MAP kinase was more efficiently coupled to the platelet-derived growth factor receptor than to any of the overexpressed receptors. All three receptors stimulated DNA synthesis to levels comparable to 10% serum, with similar sensitivities (EC(50) = 1.5-3.5 nM).
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页码:214 / 222
页数:9
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