Sepp-Lorenzino L, Ma Z, Lebwohl D E, Vinitsky A, Rosen N
Cell Biology and Genetics Program, New York, New York 10021, USA.
J Biol Chem. 1995 Jul 14;270(28):16580-7. doi: 10.1074/jbc.270.28.16580.
Herbimycin A is an ansamycin antibiotic isolated as an agent that reverses morphological transformation induced by v-src. Although herbimycin A is widely used as a tool for inhibiting multiple tyrosine protein kinases and tyrosine kinase-activated signal transduction, its mechanism of action is not well defined and includes a decrease in both tyrosine kinase protein levels and activity (Uehara, Y., Murakami, Y., Sugimoto, Y., and Mizuno, S. (1989) Cancer Res. 49, 780-785). We now show that herbimycin A induces a profound decrease in the total cellular activity of transmembrane tyrosine kinase receptors, such as insulin-like growth factor, insulin, and epidermal growth factor receptors. A substantial proportion of the in vivo inhibition could be explained by an increase in the rate of degradation. The enhanced degradation of insulin-like growth factor-insulin receptor was prevented by inhibitors of the 20S proteasome, whereas neither lysosomotropic agents nor general serine- and cysteine-protease inhibitors were active in preventing receptor degradation induced by herbimycin A. Moreover, in a temperature-sensitive mutant cell line defective in the E1-catalyzed activation of ubiquitin, herbimycin A treatment at the restrictive temperature did not result in the degradation of insulin receptor. These results suggest that herbimycin A represents a novel class of drug that targets the degradation of tyrosine kinases by the 20S proteasome. The ubiquitin dependence of this process indicates that this degradation of tyrosine kinases might involve the 20S proteasome as the proteolytic core of the ubiquitin-dependent 26S protease.
赫伯霉素A是一种安莎霉素类抗生素，作为一种能逆转由v-src诱导的形态转化的药物被分离出来。尽管赫伯霉素A被广泛用作抑制多种酪氨酸蛋白激酶和酪氨酸激酶激活的信号转导的工具，但其作用机制尚未明确，包括酪氨酸激酶蛋白水平和活性的降低（上原洋、村上洋、杉本洋、水野秀，《癌症研究》，1989年，第49卷，第780 - 785页）。我们现在表明，赫伯霉素A会导致跨膜酪氨酸激酶受体（如胰岛素样生长因子受体、胰岛素受体和表皮生长因子受体）的总细胞活性显著降低。体内抑制作用的很大一部分可以通过降解速率的增加来解释。20S蛋白酶体抑制剂可阻止胰岛素样生长因子 - 胰岛素受体的降解增强，而溶酶体促渗剂以及一般的丝氨酸和半胱氨酸蛋白酶抑制剂在阻止赫伯霉素A诱导的受体降解方面均无活性。此外，在一个E1催化的泛素激活存在缺陷的温度敏感突变细胞系中，在限制温度下用赫伯霉素A处理不会导致胰岛素受体的降解。这些结果表明，赫伯霉素A代表了一类新型药物，其作用靶点是20S蛋白酶体对酪氨酸激酶的降解。该过程对泛素的依赖性表明，酪氨酸激酶的这种降解可能涉及20S蛋白酶体作为泛素依赖性26S蛋白酶的蛋白水解核心。
