Yuan Yue, Ma Xue-Shan, Liang Qiu-Xia, Xu Zhao-Yang, Huang Lin, Meng Tie-Gang, Lin Fei, Schatten Heide, Wang Zhen-Bo, Sun Qing-Yuan
State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China.
University of Chinese Academy of Sciences, Beijing 100101, China.
J Reprod Dev. 2017 Oct 18;63(5):481-488. doi: 10.1262/jrd.2017-036. Epub 2017 Jul 9.
Geminin plays a critical role in cell cycle regulation by regulating DNA replication and serves as a transcriptional molecular switch that directs cell fate decisions. Spermatogonia lacking Geminin disappear during the initial wave of mitotic proliferation, while geminin is not required for meiotic progression of spermatocytes. It is unclear whether geminin plays a role in pre-meiotic DNA replication in later-stage spermatogonia and their subsequent differentiation. Here, we selectively disrupted Geminin in the male germline using the Stra8-Cre/loxP conditional knockout system. Geminin-deficient mice showed atrophic testes and infertility, concomitant with impaired spermatogenesis and reduced sperm motility. The number of undifferentiated spermatogonia and spermatocytes was significantly reduced; the pachytene stage was impaired most severely. Expression of cell proliferation-associated genes was reduced in Gmnn; Stra8-Cre testes compared to in controls. Increased DNA damage, decreased Cdt1, and increased phosphorylation of Chk1/Chk2 were observed in Geminin-deficient germ cells. These results suggest that geminin plays important roles in pre-meiotic DNA replication and subsequent spermatogenesis.
Geminin通过调节DNA复制在细胞周期调控中发挥关键作用，并作为指导细胞命运决定的转录分子开关。缺乏Geminin的精原细胞在有丝分裂增殖的初始阶段消失，而Geminin对于精母细胞的减数分裂进程并非必需。目前尚不清楚Geminin在后期精原细胞的减数分裂前DNA复制及其随后的分化过程中是否发挥作用。在此，我们使用Stra8-Cre/loxP条件性敲除系统在雄性生殖系中选择性地破坏Geminin。Geminin缺陷型小鼠表现出睾丸萎缩和不育，同时伴有精子发生受损和精子活力降低。未分化精原细胞和精母细胞的数量显著减少；粗线期受损最为严重。与对照组相比，Gmnn; Stra8-Cre睾丸中细胞增殖相关基因的表达降低。在Geminin缺陷的生殖细胞中观察到DNA损伤增加、Cdt1减少以及Chk1/Chk2磷酸化增加。这些结果表明Geminin在减数分裂前DNA复制和随后的精子发生中发挥重要作用。
