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Molecular mechanisms of germ cell differntiation before and during meiosis

减数分裂前和减数分裂期间生殖细胞分化的分子机制

基本信息

批准号：
14540621
负责人：
KOBAYASHI Tohru
金额：
$ 2.69万
依托单位：
Fisheries Research Agency (2004)Okazaki National Research Institutes (2002-2003)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

项目摘要

To clarify the molecular mechanisms involved in germ cell differentiation during gametogenesis, the genes involved in controlling these specialized mitotic and meiotic cell cycles of germ cell differentiation must be identified and characterized. The eel testis provides powerful experimental models for investigating the regulatory mechanisms of spermatogenesis, because this model is completely regulated by hormonal induction. To understand the control mechanisms of spermatogenesis, we isolated several kinds of cell-cycle related gene cDNAs, and investigated the relationships between cell cycle-related gene products and gametogenesis in eel testes. After the hormonal induction of spermatogenesis, cyclin E2, A2, and B (B1, B2, B3) are expressed in spermatogonia sequentially. Dmc1 and cyclin A1 become expressed in spermatogenic cells sequentially during meiosis. Although Bl and B2 are expressed in spermatogenic cells from spermatogonia to spermatcytes, cyclin B3 expression is limited duri … More ng spermatogenesis to spermatogonia. The differences in the expression patterns and MPF activities among the B-type cyclins during spermatogenesis after hormonal initiation suggests that each B-type cyclin plays a distinct role in eel spermatogenesis, and that cyclin B3 is specifically involved in spermatogonial proliferation (mitosis), but not meiosis. To clarify the role of E-type cyclins during die initiation of spermatogenesis, we examined the effects of E-type cyclins on spermatogenesis in vitro by introducing E-type cyclins by means of electroporation into testis fragments before the induction of spermatogenesis. The introduction of E-type cyclins in this manner resulted in the initiation of spermatogenesis in vitro, without the need for hormonal induction of spermatogenesis. The initiation of spermatogenesis was accompanied by massive proliferation of type B spermatogonia. but not by self-renewal proliferation of type A spermatogonia, suggesting that an increase in cyclin E2 expression after the hormonal induction of spermatogenesis plays an important role in the shift of spermatogenic cell differentiation from stem cell renewal to active spermatogenesis. Less

为了阐明配子发生过程中生殖细胞分化的分子机制，必须鉴定和表征控制生殖细胞分化的有丝分裂和减数分裂细胞周期的基因。鳗鱼精巢完全受激素诱导的调控，为研究精子发生的调控机制提供了强有力的实验模型。为了解精子发生的调控机制，本研究分离了几种细胞周期相关基因的cDNA，并研究了细胞周期相关基因产物与精子发生的关系。在激素诱导精子发生后，精原细胞依次表达细胞周期蛋白E2、A2和B（B1、B2、B3）。Dmc 1和cyclin A1在减数分裂过程中相继在生精细胞中表达。虽然B1和B2在从精原细胞到精母细胞的生精细胞中表达，但细胞周期蛋白B3的表达是有限的。 ...更多信息从精子发生到精原细胞。激素启动后精子发生过程中B型细胞周期蛋白的表达模式和MPF活性的差异表明，每个B型细胞周期蛋白在鳗鱼精子发生中起着不同的作用，细胞周期蛋白B3是专门参与精原细胞增殖（有丝分裂），但不减数分裂。为了阐明E型细胞周期蛋白在精子发生启动中的作用，我们在体外研究了E型细胞周期蛋白对精子发生的影响。以这种方式引入E型细胞周期蛋白导致体外精子发生的启动，而不需要精子发生的激素诱导。精子发生的启动伴随着大量的B型精原细胞的增殖。而不是通过A型精原细胞的自我更新增殖，这表明在激素诱导精子发生后，cyclin E2表达的增加在生精细胞从干细胞更新向活跃精子发生的分化转变中起重要作用。少