Ben-Ze'ev A, Amsterdam A
Department of Genetics, Weizmann Institute of Science, Rehovot, Israel.
Endocrinology. 1989 May;124(5):2584-94. doi: 10.1210/endo-124-5-2584.
Primary cultures of granulosa cells can be stimulated to produce large amounts of progesterone by gonadotropins. This stimulation is associated with significant changes in the expression of several major proteins, as revealed by two-dimensional gel electrophoresis. These changes include a decrease in the synthesis of actin cytoskeleton proteins and an increase in the synthesis of a few abundant proteins, one of which is a mammalian heat shock protein, hsp90. Under culture conditions that have previously been shown to bring about the maturation of granulosa cells into progesterone-producing cells (i.e. treatment with gonadotropins or cAMP or by disrupting the actin cytoskeleton with cytochalasin), an increased synthesis of hsp90 could be demonstrated. Freshly isolated granulosa cells isolated from PMSG-treated animals synthesize hsp90 at a much higher level than cells isolated from diethylstilbestrol-treated rats. Kinetic studies have shown that granulosa cells isolated from diethylstilbestrol- or PMSG-treated rats synthesize high levels of hsp90 if maintained in culture in the presence of gonadotropins, but rapidly decrease hsp90 synthesis in the absence of gonadotropins and increase the synthesis of actin cytoskeleton proteins. Furthermore, in cells cultured for 48 h in the presence of cytochalasin-B followed by incubation for 24 h in the absence of the drug, the synthesis of hsp90 and several other proteins characteristic of mature granulosa cells decreased, while that of the actin cytoskeleton increased. In vitro translation assays and Northern blot analyses suggest that hsp90 synthesis in gonadotropin-stimulated cells may be regulated by mRNA translational efficiency. Taken together with recent findings in which hsp90 was identified in complex with cytoplasmic steroid receptors and the hormonal regulation of hsp90 content in target tissues, the results support the notion that hsp90 plays a role in the control of steroid hormone action.
促性腺激素可刺激颗粒细胞的原代培养物产生大量孕酮。二维凝胶电泳显示，这种刺激与几种主要蛋白质表达的显著变化有关。这些变化包括肌动蛋白细胞骨架蛋白合成减少，以及一些丰富蛋白质的合成增加，其中一种是哺乳动物热休克蛋白hsp90。在先前已证明能使颗粒细胞成熟为产生孕酮细胞的培养条件下（即促性腺激素或cAMP处理，或用细胞松弛素破坏肌动蛋白细胞骨架），可以证明hsp90的合成增加。从经孕马血清促性腺激素（PMSG）处理的动物中分离出的新鲜颗粒细胞，其hsp90的合成水平比从己烯雌酚处理的大鼠中分离出的细胞高得多。动力学研究表明，从己烯雌酚或PMSG处理的大鼠中分离出的颗粒细胞，如果在促性腺激素存在的情况下维持培养，会合成高水平的hsp90，但在没有促性腺激素的情况下会迅速降低hsp90的合成，并增加肌动蛋白细胞骨架蛋白的合成。此外，在细胞松弛素B存在下培养48小时，然后在无药物的情况下孵育24小时，hsp90和其他几种成熟颗粒细胞特征性蛋白质的合成减少，而肌动蛋白细胞骨架的合成增加。体外翻译试验和Northern印迹分析表明，促性腺激素刺激的细胞中hsp90的合成可能受mRNA翻译效率的调节。结合最近发现hsp90与细胞质类固醇受体形成复合物，以及靶组织中hsp90含量的激素调节，这些结果支持hsp90在类固醇激素作用控制中起作用的观点。
