Transmission distortion by loss of p21 or p27 cyclin-dependent kinase inhibitors following competitive spermatogonial transplantation
Transmission distortion by loss of p21 or p27 cyclin-dependent kinase inhibitors following competitive spermatogonial transplantation
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DOI：
10.1073/pnas.0914448107
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发表时间：
2010-04-06
影响因子：
11.1
通讯作者：
Shinohara, Takashi
中科院分区：
文献类型：
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作者：
Kanatsu-Shinohara, Mito;Takashima, Seiji;Shinohara, Takashi
精原干细胞(SSCs)通过自我更新分裂来支持精子发生。虽然已经确定了几种SSC自我更新的积极调控因素，但对SSCs的负面调控机制知之甚少。在这里，我们建立了一种新的SSCs移植实验，并证明了p21和p27周期蛋白依赖的激酶抑制物在SSC自我更新和分化过程中发挥着关键作用。P21和p27的过表达抑制了体外培养的SSCs的增殖，其表达水平受外源性自我更新信号的抑制。相比之下，精原移植未发现p21或p27缺陷的SSCs存在明显缺陷。然而，与WT SSCs竞争的精原移植显示，任何一个基因的缺失都会导致生殖系传递的扭曲：p21缺乏促进突变后代的产生，而生殖系传递受到p27缺乏的限制。系列移植也表明，p27的丢失，而不是p21的丢失，减少了二次克隆的形成，这表明适量的p27是维持SSC自我更新所必需的。因此，p21和p27细胞周期蛋白依赖的激酶抑制剂通过调节SSC自我更新和分化之间的平衡在生殖系传递中发挥关键作用，竞争性精原移植技术将有助于分析传统精原移植不明显的精子发生中的细微缺陷。
Spermatogonial stem cells (SSCs) undergo self-renewal division to support spermatogenesis. Although several positive regulators of SSC self-renewal have been identified, little is known about the mechanisms that negatively regulate SSCs. Here we developed a novel transplantation assay for SSCs and demonstrate that p21 and p27 cyclin-dependent kinase inhibitors play critical roles in SSC self-renewal and differentiation. Overexpression of p21 or p27 abrogated proliferation of cultured SSCs in vitro, and their expression levels were downregulated by exogenous self-renewal signals. In contrast, no apparent defects were found in p21 or p27-deficient SSCs by spermatogonial transplantation. However, competitive spermatogonial transplantation with WT SSCs revealed that the loss of either gene causes distortion of germline transmission: p21-deficiency facilitated mutant offspring production, whereas germline transmission was limited by p27-deficiency. Serial transplantation also showed that the loss of p27, but not p21, decreases secondary colony formation, suggesting that appropriate amounts of p27 are necessary for sustaining SSC self-renewal. Thus, p21 and p27 cyclin-dependent kinase inhibitors play critical roles in germline transmission by regulating the balance between SSC self-renewal and differentiation, and competitive spermatogonial transplantation technique will be useful for analyzing subtle defects in spermatogenesis that are not evident by traditional spermatogonial transplantation.