Akt mediates self-renewal division of mouse spermatogonial stem cells
Akt mediates self-renewal division of mouse spermatogonial stem cells
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DOI：
10.1242/dev.003004
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发表时间：
2007-05-15
期刊：
影响因子：
4.6
通讯作者：
Shinohara, Takashi
中科院分区：
文献类型：
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作者：
Lee, Jiyoung;Kanatsu-Shinohara, Mito;Shinohara, Takashi
精原干细胞具有自我更新和支持精子发生的独特特性。胶质细胞源性神经营养因子（glial cell line-derived neurotrophic factor，GDNF）是近年来发现的一种精原干细胞自我更新因子，但其分子机制尚不清楚。在本研究中，我们评估了磷脂酰肌醇-3激酶（PI 3 K）-Akt通路的作用，使用生殖系干细胞（GS）细胞培养系统，允许在体外扩增精原干细胞。当GDNF加入到GS细胞培养物中时，Akt迅速磷酸化，并且加入PI 3 K的化学抑制剂阻止了GS细胞的自我更新。此外，在GDNF不存在的情况下，通过4-羟基-他莫昔芬条件性激活豆蔻酰化形式的Akt-Mer（myr-Akt-Mer）诱导GS细胞的对数增殖至少5个月。myr-Akt-Mer GS细胞表达精原标记并保留雄激素印记模式。此外，它们支持精子发生，并在精原细胞移植到不育受体小鼠的睾丸后产生后代，表明它们功能正常。这些结果表明，PI 3 K-Akt通路的激活在精原干细胞的自我更新分裂中起着核心作用。
Spermatogonial stem cells have unique properties to self-renew and support spermatogenesis throughout their lifespan. Although glial cell line-derived neurotrophic factor ( GDNF) has recently been identified as a self-renewal factor for spermatogonial stem cells, the molecular mechanism of spermatogonial stem cell self-renewal remains unclear. In the present study, we assessed the role of the phosphoinositide-3 kinase (PI3K)-Akt pathway using a germline stem (GS) cell culture system that allows in vitro expansion of spermatogonial stem cells. Akt was rapidly phosphorylated when GDNF was added to the GS cell culture, and the addition of a chemical inhibitor of PI3K prevented GS cell self-renewal. Furthermore, conditional activation of the myristoylated form of Akt-Mer (myr-Akt-Mer) by 4-hydroxy-tamoxifen induced logarithmic proliferation of GS cells in the absence of GDNF for at least 5 months. The myr-Akt-Mer GS cells expressed spermatogonial markers and retained androgenetic imprinting patterns. In addition, they supported spermatogenesis and generated offspring following spermatogonial transplantation into the testes of infertile recipient mice, indicating that they are functionally normal. These results demonstrate that activation of the PI3K-Akt pathway plays a central role in the self-renewal division of spermatogonial stem cells.