de Winter J P, Vanderstichele H M, Timmerman M A, Blok L J, Themmen A P, de Jong F H
Department of Endocrinology and Reproduction, Medical Faculty, Eramus University, Rotterdam, The Netherlands.
Endocrinology. 1993 Mar;132(3):975-82. doi: 10.1210/endo.132.3.7679985.
The production of activin by Sertoli cells isolated from 21-day-old rats was studied using the mesoderm-inducing activity of activin on Xenopus laevis animal cap explants, immunoprecipitation and Western blotting. Furthermore, the effects of recombinant bovine activin-A on rat Sertoli cell aromatase activity and FSH and androgen receptor gene expression were examined. Animal cap explants from Xenopus laevis blastulas elongated after culture in conditioned medium of Sertoli cells cultured with or without ovine FSH or conditioned medium of the mouse Sertoli cell-derived TM4 cell line. Animal cap explants cultured in control medium remained spherical. This elongation was also found in the more than 10-kilodalton fraction of the conditioned medium and after heating for 10 min at 95 C, indicating that heat-stable activin-like bioactivity is present in the culture medium. Immunoprecipitation of [35S]methionine-labeled proteins and Western blotting of Sertoli cell-conditioned medium with polyclonal antisera against the inhibition beta-subunits indicated the presence of 24- to 25-kilodalton activin-like immunoreactive material. Sertoli cell aromatase activity was dose-dependently stimulated by ovine FSH after 72 h of culture. Recombinant bovine activin-A partly inhibited this stimulation in a dose-dependent way. This inhibition was also found after 24 h of culture. Furthermore, basal and FSH-stimulated androgen receptor mRNA expression in Sertoli cells and binding of the synthetic androgen R1881 to Sertoli cells were decreased after 24 h of culture in the presence of recombinant bovine activin-A. In the same experiments, FSH receptor mRNA expression was not significantly affected. These results indicate that activin can act as an autocrine regulator of Sertoli cell function.
利用激活素对非洲爪蟾动物帽外植体的中胚层诱导活性、免疫沉淀和蛋白质印迹法，研究了从21日龄大鼠分离的支持细胞中激活素的产生。此外，还检测了重组牛激活素-A对大鼠支持细胞芳香化酶活性以及促卵泡激素（FSH）和雄激素受体基因表达的影响。非洲爪蟾囊胚的动物帽外植体在用或不用羊FSH培养的支持细胞条件培养基或小鼠支持细胞来源的TM4细胞系条件培养基中培养后伸长。在对照培养基中培养的动物帽外植体保持球形。这种伸长也在条件培养基的大于10千道尔顿的组分中以及在95℃加热10分钟后发现，表明培养基中存在热稳定的激活素样生物活性。用针对抑制性β亚基的多克隆抗血清对[35S]甲硫氨酸标记的蛋白质进行免疫沉淀以及对支持细胞条件培养基进行蛋白质印迹，结果表明存在24至25千道尔顿的激活素样免疫反应性物质。培养72小时后，羊FSH以剂量依赖性方式刺激支持细胞芳香化酶活性。重组牛激活素-A以剂量依赖性方式部分抑制这种刺激。在培养24小时后也发现了这种抑制作用。此外，在存在重组牛激活素-A的情况下培养24小时后，支持细胞中基础和FSH刺激的雄激素受体mRNA表达以及合成雄激素R1881与支持细胞的结合减少。在相同实验中，FSH受体mRNA表达未受到显著影响。这些结果表明激活素可作为支持细胞功能的自分泌调节因子。
