Growth hormone action in rat insulinoma cells expressing truncated growth hormone receptors.
Growth hormone action in rat insulinoma cells expressing truncated growth hormone receptors.
复制标题
表达截短的生长激素受体的大鼠胰岛素瘤细胞中生长激素的作用。
DOI：
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发表时间：
1991
影响因子：
4.8
通讯作者：
N. Billestrup
中科院分区：
文献类型：
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作者：
A. Møldrup;G. Allevato;T. Dyrberg;J. Nielsen;N. Billestrup
将大鼠肝脏生长激素(GH)受体(GH-R1-638)的全长cDNA导入胰岛素产生大鼠胰岛肿瘤细胞系RIN-5AH，可增加这些细胞对GH反应的胰岛素合成。利用这个功能系统，我们分析了生长激素受体COOH末端截断的影响。通过定点突变获得了两个编码截短的生长激素受体的突变基因GH-R1-294和GH-R1-454，并将其导入RIN细胞。两种受体突变体均在细胞表面表达，表现出正常的生长激素结合亲和力。GH-R1-638的分子质量约为110 kDa，GH-R1-294和GH-R1-454的分子质量分别为49 kDa和80 kDa。表达GH-R1-454的细胞对GH的内化程度与全长受体和亲本细胞相似，但表达GH-R1-294的细胞对GH内化的能力明显降低。与GH-R1-638细胞相比，表达截短的GH受体的细胞株在GH刺激下的胰岛素产生没有任何增加。我们的结论是，GH受体胞浆部分COOH末端半部分内的区域是GH刺激的胰岛素合成信号转导所必需的，而跨膜区附近的胞质区域参与了受体介导的GH内化。
Transfection of the insulin-producing rat islet tumor cell line RIN-5AH with a full length cDNA of the rat hepatic growth hormone (GH) receptor (GH-R1-638) augments the GH-responsive insulin synthesis in these cells. Using this functional system we analyzed the effect of COOH-terminal truncation of the GH receptor. Two mutated cDNAs encoding truncated GH receptors, GH-R1-294 and GH-R1-454, respectively, were generated by site-directed mutagenesis and transfected into the RIN cells. Both receptor mutants were expressed on the cell surface and displayed normal GH binding affinity. Whereas GH-R1-638 had a molecular mass of about 110 kDa, GH-R1-294 and GH-R1-454 showed molecular masses of 49 and 80 kDa, respectively. Cells expressing GH-R1-454 internalized GH to a similar extent as cells transfected with the full length receptor and the parent cell line, but GH-R1-294-expressing cells showed a markedly reduced capability of GH internalization. In contrast to cells transfected with GH-R1-638, none of the cell lines expressing truncated GH receptors exhibited any increase of the GH-stimulated insulin production. We conclude that domains within the COOH-terminal half of the cytoplasmic part of the GH receptor are required for transduction of the signal for GH-stimulated insulin synthesis, whereas cytoplasmic domains proximal to the transmembrane region are involved in receptor-mediated GH internalization.