Genetic Reconstruction of Mouse Spermatogonial Stem Cell Self-Renewal In Vitro by Ras-Cyclin D2 Activation
Genetic Reconstruction of Mouse Spermatogonial Stem Cell Self-Renewal In Vitro by Ras-Cyclin D2 Activation
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DOI：
10.1016/j.stem.2009.04.020
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发表时间：
2009-07-02
期刊：
影响因子：
23.9
通讯作者：
Shinohara, Takashi
中科院分区：
文献类型：
--
作者：
Lee, Jiyoung;Kanatsu-Shinohara, Mito;Shinohara, Takashi
精原干细胞（SSC）进行自我更新分裂并支持精子发生。尽管多种细胞因子协调驱动SSC自我更新，但人们对这一过程背后的机制知之甚少。我们通过在体外重建SSC自我更新而无需外源细胞因子来研究其分子机制。 Ras 激活或细胞周期蛋白 D2 和 E1 过度表达，两者均由 Ras 诱导；使培养的精原细胞能够长期自我更新。具有激活Ras的SSC对分化信号做出正确反应并进行精子发生，而精原细胞移植后细胞周期蛋白转染子的分化被消除。 Ras 和细胞周期蛋白转染的细胞均产生精原细胞瘤，表明过度的自我更新刺激会诱导致癌转化。相反，过度表达细胞周期蛋白 D1 或 D3 的细胞在移植后未能形成生殖细胞集落，这表明细胞周期蛋白表达模式是长期 SSC 重新定植的重要决定因素。因此，Ras-cyclin D2 通路调节 SSC 群体中组织维持和肿瘤发生之间的平衡。
Spermatogonial stem cells (SSCs) undergo self-renewal division and support spermatogenesis. Although several cytokines coordinate to drive SSC self-renewal, little is known about the mechanisms underlying this process. We investigated the molecular mechanism by reconstructing SSC self-renewal in vitro without exogenous cytokines. Activation of Ras or overexpression of cyclins D2 and E1, both of which were induced by Ras; enabled long-term self-renewal of cultured spermatogonia. SSCs with activated Ras responded properly to differentiation signals and underwent spermatogenesis, whereas differentiation was abrogated in cyclin transfectants after spermatogonial transplantation. Both Ras- and cyclin-transfected cells produced seminomatous tumors, suggesting that excessive self-renewing stimulus induces oncogenic transformation. In contrast, cells that overexpressed cyclin D1 or D3 failed to make germ cell colonies after transplantation, which indicated that cyclin expression pattern is an important determinant to long-term SSC recolonization. Thus, the Ras-cyclin D2 pathway regulates the balance between tissue maintenance and tumorigenesis in the SSC population.