Role of Bcl-x in Murine Spermatogenesis

Bcl-x 在小鼠精子发生中的作用

• 批准号: 6573020
• 负责人: EDMUND B RUCKER
• 金额: $ 7.25万
• 依托单位: UNIVERSITY OF MISSOURI-COLUMBIA
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-04-02 至 2005-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6573020
• 关键词: Bax gene /protein; RNase protection assay; apoptosis; cell growth regulation; cell proliferation; fertility; gene expression; gene interaction; gene targeting; genetic regulation; genetically modified animals; genotype; immunocytochemistry; laboratory mouse; protooncogene; spermatogenesis; testis

DESCRIPTION (provided by applicant): Apoptosis, or programmed cell death, is a biochemical process that is mediated by a concert of cellular proteins including receptor "initiators" (e.g., TNFR tumor necrosis factor receptor superfamily), the mitochondrial-associating Bcl-2 family "mediators" (e.g., Bcl-2, Bax, Bcl-XL), and the protease "executioners" (e.g., caspases). Spermatogenesis can be blocked by the overexpression or deletion of these apoptosis-related genes, leading to male infertility or sterility. For example, ectopic expression of Bcl-2 and Bcl-x in transgenic mice inhibits apoptosis of spermatogonia and causes infertility. In addition, Bcl-x is expressed in the mouse and human testis within spermatogonia and spermatocytes. Due to the embryonic lethality associated with the bcl-x null mutation, it has not been possible to ascertain the role of Bcl-x in gamete development. Preliminary data support the hypothesis that Bcl-x is required to maintain the survival of spermatogonia and spermatocytes during murine spermatogenesis. To address this hypothesis the following specific aims are proposed. Specific Aim 1: Determine whether Bcl-x maintains the survival of spermatogonial cell populations in the mouse testes. To do this, we ablate the bcl-x gene in murine spermatocytes using the Cre-lox system. This approach will reveal the role of Bcl-x in spermatocyte survival in the mouse testis. Specific Aim 2: Determine whether Bcl-x and Bax are antagonists in the fate determination of the spermatogonial cell populations in the mouse testes. To do this, we will generate double mouse mutants that lack both the bcl-x and bax genes derived from Cre-lox (bcl-x) and conventional (bax) gene knockout strategies. Resultant mutants will demonstrate whether Bcl-x and Bax compete in determining the apoptotic fate of spermatocytes during murine spermatogenesis.

描述（由申请人提供）：细胞凋亡或程序性细胞死亡是一个生化过程，是由一系列细胞蛋白介导的，包括受体“启动剂”（如TNFR肿瘤坏死因子受体超家族）、线粒体相关的Bcl-2家族“介质”（如Bcl-2、Bax、Bcl-XL）和蛋白酶“刽子手”（如半胱天蛋白酶）。这些细胞凋亡相关基因的过度表达或缺失可阻断精子发生，导致男性不育或不育。例如，转基因小鼠中异位表达Bcl-2和Bcl-x可抑制精原细胞凋亡，导致不育。此外，Bcl-x在小鼠和人睾丸精原细胞和精母细胞内表达。由于与bcl-x零突变相关的胚胎致死率，不可能确定bcl-x在配子发育中的作用。初步数据支持了Bcl-x在小鼠精子发生过程中维持精原细胞和精母细胞存活所必需的假设。为了解决这一假设，提出了以下具体目标。特异性目的1：确定Bcl-x是否维持小鼠睾丸中精原细胞群的存活。为此，我们使用Cre-lox系统消融小鼠精细胞中的bcl-x基因。这种方法将揭示Bcl-x在小鼠睾丸精细胞存活中的作用。特异性目的2：确定Bcl-x和Bax在小鼠睾丸精原细胞群的命运决定中是否为拮抗剂。为此，我们将从Cre-lox （bcl-x）和常规（bax）基因敲除策略中产生缺乏bcl-x和bax基因的双小鼠突变体。由此产生的突变体将证明Bcl-x和Bax是否在决定小鼠精子发生过程中精母细胞凋亡的命运中相互竞争。