IGF-1R Signaling Is Essential for the Proliferation of Cultured Mouse Spermatogonial Stem Cells by Promoting the G2/M Progression of the Cell Cycle
IGF-1R Signaling Is Essential for the Proliferation of Cultured Mouse Spermatogonial Stem Cells by Promoting the G2/M Progression of the Cell Cycle
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DOI：
10.1089/scd.2014.0376
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发表时间：
2015-02-15
影响因子：
4
通讯作者：
Han, Chunsheng
中科院分区：
文献类型：
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作者：
Wang, Si;Wang, Xiuxia;Han, Chunsheng
小鼠精原干细胞的培养有助于了解哺乳动物精子发生的机制。已知几种关键生长因子如GDNF和FGF 2对于培养的mSSC的增殖是必需的。然而，调节SSC增殖的其他因素仍有待确定。在这项研究中，我们报告说，IGF-1 R信号是所需的培养mSSC的增殖，通过促进细胞周期的G（2）/M进程。IGF-1及其受体IGF-1 R在培养的mSSC以及分离的支持细胞和间质细胞中表达。通过敲低IGF-1 R或IGF-1 R特异性抑制剂苦鬼臼脂素（PPP）阻断IGF-1 R信号传导可显著降低mSSC的增殖，增加其凋亡，并以胰岛素非依赖性方式损害其干细胞活性。PPP处理mSSC可阻断G（2）/M进展。相反，GDNF的撤出和FGF 2信号传导阻断减少了mSSC进入其S期。结论：IGF-1促进胸腺嘧啶处理的mSSCs的G（2）/M期进程，并使其在G（1）/S期同步阻滞;而GDNF和/或FGF 2则促进其进入S期。此外，IGF-1激活AKT的磷酸化，但不激活ERK 1/2的磷酸化。这些结果表明，IGF-1 R信号刺激mSSCs的增殖，使用一个不同的机制，从GDNF和FGF 2，并将有助于建立一个化学定义的培养系统。
Culture of mouse spermatogonial stem cells (mSSCs) contributes to understanding the mechanisms of mammalian spermatogenesis. Several key growth factors such as GDNF and FGF2 have been known to be essential for the proliferation of cultured mSSCs. However, additional factors regulating SSC proliferation remain to be identified. In this study, we report that IGF-1R signaling is required for the proliferation of cultured mSSCs by promoting the G(2)/M progression of the cell cycle. IGF-1 and its receptor IGF-1R are expressed in cultured mSSCs as well as in isolated Sertoli cells and interstitial cells. Blockage of IGF-1R signaling either by knockdown of IGF-1R or by the IGF-1R-specific inhibitor picropodophyllin (PPP) significantly reduced the proliferation of mSSCs, increased their apoptosis, and impaired their stem cell activity in an insulin-independent manner. PPP treatment of mSSCs blocked the G(2)/M progression. In contrast, both GDNF withdrawal and FGF2 signaling blockade decreased the entry of mSSCs into their S phases. Consistently, IGF-1 promoted the G(2)/M progression of thymidine-treated mSSCs, which were arrested at G(1)/S boundary synchronously; while GDNF and/or FGF2 stimulated their entry into the S phase. Moreover, IGF-1 activated the phosphorylation of AKT but not that of ERK1/2 in mSSCs. These results indicate that IGF-1R signaling stimulates the proliferation of mSSCs using a distinct mechanism from those by GDNF and FGF2, and will contribute to the establishment of a chemically defined culture system.