Lin Yuan-Feng, Tseng Min-Jen, Hsu Hui-Ling, Wu Yu-Wei, Lee Yi-Hsuan, Tsai Yu-Hui
Graduate Institute of Pharmaceutical Science, Medical School, Taipei Medical University, Taipei, Taiwan 110, Republic of China.
Mol Endocrinol. 2006 Oct;20(10):2514-27. doi: 10.1210/me.2005-0347. Epub 2006 May 18.
FSH is known to activate Gs/cAMP signaling pathway in Sertoli cells (SCs) to support spermatogenesis. However, the molecular mechanism of FSH-induced Gs/cAMP-independent Ca2+-influx in SCs is not clear. In this study, FSH indeed induced an immediate and dose-dependent intracellular Ca2+-elevation in rat SCs. In the presence of EDTA (2.5 mm) or in the absence of extracellular Ca2+, the FSH-induced intracellular Ca2+-elevation was abolished. The confocal microscopic observation of Ca2+ image revealed that the SC cellular Ca2+ level was gradually increased after 50 sec of FSH treatment. Dantrolene, a blocker of intracellular Ca2+ release, did not affect this FSH-induced intracellular Ca2+ elevation. The pretreatment of rat SCs with phosphatidylinositol-phospholipase C (PLC)-specific inhibitor, U73122 (3 and 10 microm), inhibited the FSH-induced Ca2+-influx in a dose-dependent manner, but treatment with Gs-specific inhibitor, NF449 (0.1 and 0.3 microm), did not. On the other hand, the activation of G alpha h was immediately induced by FSH in the rat SCs within 5 sec of treatment. The translocation of PLC-delta1 from cytosol to cell membrane and the formation of G alpha h /PLC-delta1 complexes occurred within 5 and 10 sec, respectively, of FSH exposure. The intracellular inositol 1,4,5-triphosphate (IP3) production was also detected after 30 sec of FSH treatment. The synthetic peptide of PLC-delta1 (TIPWNSLKQGYRHVHLL), not Gs inhibitor, predominantly inhibited the FSH-induced PLC-delta1 translocation, formation of G alpha h /PLC-delta1 complex, intracellular IP3 production, and Ca2+ influx. In contrast, the peptide did not interfere with FSH-induced intracellular cAMP accumulation. In conclusion, the FSH-induced immediate Ca2+ influx is unambiguously mediated by an alternative G alpha h /PLC-delta1/IP3 pathway that is distinct from the Gs/cAMP pathway in rat SCs.
已知促卵泡激素（FSH）可激活支持生精作用的支持细胞（SCs）中的Gs/环磷酸腺苷（cAMP）信号通路。然而，FSH诱导支持细胞中Gs/cAMP非依赖性Ca2+内流的分子机制尚不清楚。在本研究中，FSH确实在大鼠支持细胞中诱导了即时且剂量依赖性的细胞内Ca2+升高。在存在乙二胺四乙酸（EDTA，2.5 mM）的情况下或在无细胞外Ca2+时，FSH诱导的细胞内Ca2+升高被消除。Ca2+图像的共聚焦显微镜观察显示，FSH处理50秒后支持细胞的细胞内Ca2+水平逐渐升高。丹曲林，一种细胞内Ca2+释放阻滞剂，不影响这种FSH诱导的细胞内Ca2+升高。用磷脂酰肌醇 - 磷脂酶C（PLC）特异性抑制剂U73122（3和10微摩尔）预处理大鼠支持细胞，以剂量依赖性方式抑制FSH诱导的Ca2+内流，但用Gs特异性抑制剂NF449（0.1和0.3微摩尔）处理则无此作用。另一方面，FSH在处理大鼠支持细胞5秒内立即诱导Gαh激活。FSH暴露5秒和10秒内分别发生PLC - δ1从胞质溶胶向细胞膜的转位以及Gαh / PLC - δ1复合物的形成。FSH处理30秒后还检测到细胞内肌醇1,4,5 - 三磷酸（IP3）的产生。PLC - δ1的合成肽（TIPWNSLKQGYRHVHLL）而非Gs抑制剂主要抑制FSH诱导的PLC - δ1转位、Gαh / PLC - δ1复合物的形成、细胞内IP3产生和Ca2+内流。相反，该肽不干扰FSH诱导的细胞内cAMP积累。总之，FSH诱导的即时Ca2+内流明确地由一条不同于大鼠支持细胞中Gs/cAMP途径的替代性Gαh / PLC - δ1 / IP3途径介导。
