Hamel F G, Bennett R G, Harmon K S, Duckworth W C
Medical Research Service, Department of Veterans Affairs Medical Center, Omaha, Nebraska 68105, USA.
Biochem Biophys Res Commun. 1997 May 29;234(3):671-4. doi: 10.1006/bbrc.1997.6693.
Cellular homeostasis requires regulation of protein turnover. Protein degradation is an essential component of this process and is inhibited by insulin. The importance of cytosolic proteolysis in overall cellular protein degradation is increasingly apparent and an insulin effect on this system has been suggested but not proven. The present study shows that a membrane permeable substrate of the proteasome is degraded in HepG2 cells and that insulin inhibits its degradation both by isolated proteasomes and by intact cells. Inhibitors of the proteasome suppress degradation, and in the presence of these inhibitors insulin has no further effect. This is the first demonstration that insulin inhibition of cellular protein degradation is due to an effect on proteasomes.
细胞内稳态需要对蛋白质周转进行调节。蛋白质降解是这一过程的重要组成部分，且受到胰岛素的抑制。胞质蛋白水解在整体细胞蛋白质降解中的重要性日益明显，并且有人提出胰岛素对该系统有影响，但尚未得到证实。本研究表明，蛋白酶体的一种膜可渗透底物在HepG2细胞中被降解，并且胰岛素通过分离的蛋白酶体和完整细胞抑制其降解。蛋白酶体抑制剂可抑制降解，在这些抑制剂存在的情况下，胰岛素没有进一步的作用。这首次证明胰岛素对细胞蛋白质降解的抑制作用是由于对蛋白酶体的影响。
