Evans R B, Morhenn V, Jones A L, Tomkins G M
J Cell Biol. 1974 Apr;61(1):95-106. doi: 10.1083/jcb.61.1.95.
By scanning and transmission electron microscopy we have shown that insulin rapidly reversed changes in surface membrane conformation and polysome profile induced by the transfer of actively growing Balb/c 3T3 fibroblasts from a serum-containing to a serum-free medium. Morphometric analysis of polysome profiles revealed a 94% aggregation of total f ribosomes during logarithmic growth. This figure fell to 78% after 18 h of serum starvation. The number of f ribosomes per unit area of cytoplasm also fell. 1 h of insulin treatment restored aggregation to 92% and increased the number of f ribosomes per unit area of cytoplasm by 22%. Scanning electron microscopy of logarithmically growing cells revealed an abundance of surface microvilli, whereas serum starvation promoted a smooth surface with few microvilli. After 1 h of insulin treatment, microvilli reappeared with a distribution and subcellular organization characteristic of exponential growth. This study shows the combined and rapid effect of insulin on the regulation of polysome formation and the promotion of a specific surface membrane conformation in cultured cells. The observations are consistent with the knowledge that insulin, acting on the surface membrane, can influence such parameters as membrane transport, and the rates of protein and RNA synthesis.
通过扫描电子显微镜和透射电子显微镜，我们发现胰岛素能够迅速逆转因将活跃生长的Balb/c 3T3成纤维细胞从含血清培养基转移至无血清培养基而诱导的表面膜构象和多核糖体图谱的变化。对多核糖体图谱的形态计量分析显示，在对数生长期，总f核糖体的聚集率为94%。血清饥饿18小时后，这一数字降至78%。细胞质单位面积内的f核糖体数量也有所下降。胰岛素处理1小时后，聚集率恢复至92%，细胞质单位面积内的f核糖体数量增加了22%。对数生长期细胞的扫描电子显微镜观察显示表面有大量微绒毛，而血清饥饿则促使细胞表面变得光滑，微绒毛减少。胰岛素处理1小时后，微绒毛重新出现，其分布和亚细胞组织具有指数生长的特征。本研究显示了胰岛素对培养细胞中多核糖体形成调控和特定表面膜构象促进的联合快速作用。这些观察结果与胰岛素作用于表面膜可影响诸如膜转运以及蛋白质和RNA合成速率等参数的认识相一致。
