Transforming growth factor-beta promotes differentiation of ovarian thecal-interstitial cells but inhibits androgen production.
Transforming growth factor-beta promotes differentiation of ovarian thecal-interstitial cells but inhibits androgen production.
复制标题
转化生长因子-β 促进卵巢膜间质细胞的分化，但抑制雄激素的产生。
作者：
D. Magoffin;B. Gancedo;G. Erickson
有证据表明，转化生长因子β（TGF β）是由卵泡膜间质细胞（TIC）产生的，这表明TGF β可能是TIC功能的自分泌调节因子。这些研究的目的是开始检验这一假设。在本实验中，我们通过Percoll梯度离心法从切除垂体的未成熟大鼠的卵巢中分离的TIC测试了TGF β对类固醇产生的影响。当TIC（10（4）个活细胞/孔）在无血清培养基（96孔板中0.2ml）中培养时，在第2、4和6天产生少量的雄酮（小于4 ng/ml）。TGF β（0.01-100 ng/ml）不改变基础雄酮的产生。LH（50 ng/ml）治疗刺激雄酮在第2天增加100倍，在第4天和第6天增加60倍。与TGF β（10 ng/ml）的伴随治疗在每个时间段引起雄酮产生的65%抑制（ED 50 = 2.3 +/- 0.7 ng/ml）。对关键类固醇代谢物的分析表明，雄酮和雄烯二酮受到同等抑制，而孕酮显著增加（ED 50 = 1.2 +/- 0.2 ng/ml）。时程研究显示，单独的TGF β在2天时不改变孕酮的产生，但在4天和6天时显著增加孕酮（10倍）超过对照水平。剂量反应实验表明，TGF β并没有改变TIC对LH刺激的敏感性，表明细胞内信号通路的LH激活没有被TGF β阻断。胰岛素样生长因子-I（IGF-I）与LH一起治疗引起雄酮产量的协同增加。IGF-1对LH作用的协同刺激作用可被TGF β阻断。有趣的是，TIC在IGF-I存在下对TGF β更敏感（ED 50 = 0.18 +/- 0.04 ng/ml）。相比之下，TGF β仅在最高剂量的TGF β（10 ng/ml）下增强孕酮产生。为了进一步阐明TGF β作用的机制，通过免疫印迹分析TGF β对17 α-羟化酶/C17-20裂解酶（P450（17）α）和胆固醇侧链裂解（P450 SCC）的TIC含量的影响。TGF β单独或与LH联合刺激P450 SCC含量增加，但不改变P450 α含量。这些结果使我们得出结论：1）TIC是TGF β的靶点; 2）IGF-I增加TIC对TGF β作用的敏感性; 3）TGF β直接作用于TIC以刺激孕酮，同时抑制雄激素产生。
Evidence that transforming growth factor-beta (TGF beta) is produced by thecal-interstitial cells (TIC) has suggested the hypothesis that TGF beta may be an autocrine regulator of TIC function. The purpose of these studies is to begin to test this hypothesis. In the present experiments we tested the effects of TGF beta on steroid production by TIC isolated from the ovaries of hypophysectomized immature rats by Percoll gradient centrifugation. When TIC (10(4) viable cells/well) were cultured in serum-free medium (0.2 ml in 96-well plates), low amounts of androsterone (less than 4 ng/ml) were produced at 2, 4, and 6 days. TGF beta (0.01-100 ng/ml) did not change basal androsterone production. Treatment with LH (50 ng/ml) stimulated a 100-fold increase in androsterone at 2 days and 60-fold increases at 4 and 6 days. Concomitant treatment with TGF beta (10 ng/ml) caused a 65% inhibition (ED50 = 2.3 +/- 0.7 ng/ml) of androsterone production at each time period. Analysis of key steroid metabolites demonstrated that androsterone and androstenedione were inhibited equally, while progesterone was significantly increased (ED50 = 1.2 +/- 0.2 ng/ml). Time-course studies revealed that TGF beta alone did not alter progesterone production at 2 days, but markedly increased progesterone (10-fold) above control levels at 4 and 6 days. Dose-response experiments showed that TGF beta did not alter the sensitivity of the TIC to LH stimulation, indicating that LH activation of the intracellular signaling pathway was not blocked by TGF beta. Treatment with insulin-like growth factor-I (IGF-I) together with LH caused a synergistic increase in androsterone production. The synergistic stimulation of LH action by IGF-I could be blocked by TGF beta. Interestingly, TIC were more sensitive to TGF beta in the presence of IGF-I (ED50 = 0.18 +/- 0.04 ng/ml). In contrast, TGF beta enhanced progesterone production only at the highest dose of TGF beta (10 ng/ml). To further elucidate the mechanism of TGF beta action, the effects of TGF beta on the TIC content of 17 alpha-hydroxylase/C17-20 lyase (P450(17)alpha) and cholesterol side-chain cleavage (P450scc) were analyzed by immunoblotting. TGF beta alone or in combination with LH stimulated an increase in P450scc content, but did not alter P450(17 alpha content. These results lead us to conclude that 1) the TIC are targets for TGF beta; 2) IGF-I increases the sensitivity of TIC to TGF beta action; and 3) TGF beta acts directly on TIC to stimulate progesterone while inhibiting androgen production.