Department of Biochemistry, University of California, 900 University Ave., Riverside, CA 92521, USA.
J Steroid Biochem Mol Biol. 2010 Apr;119(3-5):127-34. doi: 10.1016/j.jsbmb.2010.01.011. Epub 2010 Feb 13.
Sertoli cell secretory activities are highly dependent on ion channel functions and critical to spermatogenesis. The steroid hormone 1alpha,25(OH)2-vitamin D3 (1,25(OH)2-D3) stimulates exocytosis in different cell systems by activating a nongenotropic vitamin D receptor (VDR). Here, we described 1,25(OH)2-D3 stimulation of secretion via Cl(-) channel activation in the mouse immature Sertoli cell line TM4. 1,25(OH)2-D3 potentiation of chloride currents was dependent on hormone concentration, and correlated with a significant increase in whole-cell capacitance within 20-40 min. In addition, Cl(-) currents were potentiated by the nongenomic VDR agonist 1alpha,25(OH)2 lumisterol D3 (JN), while 1,25(OH)2-D3 potentiation of channels was suppressed by nongenomic VDR antagonist 1beta,25(OH)2-vitamin D3 (HL). Treatment of TM4 cells with PKC and PKA activators PMA and forskolin respectively, increased Cl(-) currents significantly, while PKC and PKA inhibitors Go6983 and H-89, respectively, abolished 1,25(OH)2-D3 stimulation of Cl(-) currents, suggesting phosphorylation pathways in 1,25(OH))2-D3 mediated channel responses. RT-PCR demonstrated the expression of outwardly rectifying ClC-3 channels in TM4 cells. Taken together, our results demonstrate a PKA/PKC-dependent 1,25(OH)2-D3/VDR nongenotropic pathway leading to Cl(-) channel and exocytosis activation in Sertoli cells. We conclude that 1,25(OH)2-D3 appears to be a modulator of male reproductive functions at least in part by stimulating Sertoli cell secretory functions.
支持细胞的分泌活动高度依赖于离子通道的功能，对精子发生至关重要。类固醇激素 1α，25（OH）2-维生素 D3（1，25（OH）2-D3）通过激活非基因维生素 D 受体（VDR）刺激不同细胞系统的胞吐作用。在这里，我们描述了 1，25（OH）2-D3 通过激活小鼠未成熟支持细胞系 TM4 中的 Cl(-)通道来刺激分泌。1，25（OH）2-D3 对氯离子电流的增强作用取决于激素浓度，并与 20-40 分钟内全细胞电容的显著增加相关。此外，非基因组 VDR 激动剂 1α，25（OH）2 lumisterol D3（JN）增强 Cl(-)电流，而非基因组 VDR 拮抗剂 1β，25（OH）2-维生素 D3（HL）抑制通道的增强作用。分别用 PKC 和 PKA 激活剂 PMA 和 forskolin 处理 TM4 细胞，显著增加 Cl(-)电流，而 PKC 和 PKA 抑制剂 Go6983 和 H-89 分别消除 1，25（OH）2-D3 对 Cl(-)电流的刺激，表明 1，25（OH）2-D3 介导的通道反应中存在磷酸化途径。RT-PCR 证明 TM4 细胞中存在外向整流 ClC-3 通道。总之，我们的结果表明，PKA/PKC 依赖性 1，25（OH）2-D3/VDR 非基因途径导致支持细胞中 Cl(-)通道和胞吐作用的激活。我们得出结论，1，25（OH）2-D3 似乎至少部分通过刺激支持细胞分泌功能来调节男性生殖功能。
