Brunetti A, Maddux B A, Wong K Y, Goldfine I D
Cell Biology Laboratory, Mount Zion Hospital and Medical Center, San Francisco, California 94115.
J Clin Invest. 1989 Jan;83(1):192-8. doi: 10.1172/JCI113858.
Muscle is a major tissue for insulin action. To study the effect of muscle differentiation on insulin receptors, we employed cultured mouse muscle BC3H-1 and C2 cells. In both cell lines differentiation from myoblasts to myocytes was associated with a 5-10-fold increase in specific 125I-insulin binding to intact cells. When 125I-insulin binding was carried out on solubilized myocytes and myoblasts, 125I-insulin binding to myoblasts was low. After differentiation the number of insulin receptors increased 5-10-fold. In contrast to insulin binding, insulin growth factor I receptor binding was elevated in myoblasts and was decreased by 50% in myocytes. Specific radioimmunoassay of the insulin receptor indicated that the increase in insulin binding to myocytes was due to an increase in insulin receptor content. Studies employing [35S]methionine indicated that this increase in insulin-binding sites reflected an increase in insulin receptor biosynthesis. To study insulin receptor gene expression, myoblast and myocyte mRNA was isolated and analyzed on Northern and slot blots. Differentiation from myoblasts to myocytes was accompanied by a 5-10-fold increase in insulin receptor mRNA. These studies demonstrate, therefore that differentiation in muscle cells is accompanied by increased insulin receptor biosynthesis and gene expression.
肌肉是胰岛素发挥作用的主要组织。为了研究肌肉分化对胰岛素受体的影响，我们使用了培养的小鼠肌肉BC3H-1细胞和C2细胞。在这两种细胞系中，从成肌细胞向肌细胞的分化都与完整细胞对125I胰岛素特异性结合增加5至10倍有关。当对溶解的肌细胞和成肌细胞进行125I胰岛素结合实验时，成肌细胞对125I胰岛素的结合能力较低。分化后胰岛素受体数量增加了5至10倍。与胰岛素结合情况相反，胰岛素生长因子I受体的结合在成肌细胞中升高，而在肌细胞中降低了50%。对胰岛素受体进行特异性放射免疫测定表明，肌细胞对胰岛素结合能力的增加是由于胰岛素受体含量的增加。采用[35S]甲硫氨酸的研究表明，胰岛素结合位点的增加反映了胰岛素受体生物合成的增加。为了研究胰岛素受体基因表达，分离了成肌细胞和肌细胞的mRNA，并在Northern印迹和狭缝印迹上进行分析。从成肌细胞向肌细胞的分化伴随着胰岛素受体mRNA增加5至10倍。因此，这些研究表明，肌肉细胞的分化伴随着胰岛素受体生物合成和基因表达的增加。
