TRANSCRIPTIONAL CONTROL OF SPERMATOGENESIS

精子发生包括几个发育阶段， 精原干细胞增殖并分化为 精子 该系统为研究提供了一个很好的模型 细胞分化由于生物化学表征的能力， 离散的精子发生阶段。 然而，机制 潜在的男性生殖细胞发育和相关阶段-和 细胞特异性基因表达知之甚少，特别是在 转录水平。 最近的研究表明， 转录因子CREMtau对细胞增殖的最后阶段至关重要， 精子发育，精子发生。 然而， 减数分裂和粗线期的形成需要机制 精母细胞和单倍体圆形精子细胞。 我们一直在使用 转基因小鼠，以表征生精细胞特异性 脑啡肽原启动子，其以阶段依赖性方式表达 粗线期精母细胞和圆形精子细胞的方式。 一 位于近端5' -区的51-bp序列对于 生殖细胞特异性表达，以及存在的新重复元件 在这个区域内，特别需要。 这些重复 序列与称为PACH 1的因子结合，其活性是 在粗线期精母细胞中上调。 我们还发现 TATA结合蛋白（TBP）的表达在 粗线期精母细胞和圆形精母细胞中转录水平 精子细胞 这一介绍可能反映了专门的要求 与男性生殖细胞发育有关。 其目的是 我们的主要工作是：1）对PACH 1蛋白进行克隆和鉴定 用表达克隆方法从大鼠生精细胞中分离出精子; 2)全面分析脑啡肽原中的顺式作用元件 生殖系启动子，特别关注重复元件， 潜在的调控位点位于下游;以及3）分离和 初步表征TATA结合蛋白的调节 启动子在精子发生中的作用。 这些研究将有望 提供子重要新见解转录调控 减数分裂和单倍体细胞的形成，并可能最终相关 男性不育症和避孕。

Spermatogenesis consists of developmental stages during which spermatogonial stem cells proliferate and differentiate into spermatozoa. This system provides an excellent model for studying cell differentiation due to the ability to biochemically characterize discrete spermatogenic stages. However, the mechanisms underlying male germ cell development and associated stage- and cell-specific gene expression are poorly understood, especially at the transcriptional level. Recent studies have demonstrated that the transcription factor CREMtau is critical for the final phase of sperm development, spermiogenesis. However, distinct mechanisms are required for meiosis and formation of pachytene spermatocytes and haploid round spermatids. We have been using transgenic mice to characterize the spermatogenic cell-specific proenkephalin promoter, which is expressed in a stage-dependent manner in pachytene spermatocytes and round spermatids. A 51-bp sequence located in the proximal 5' -region is critical for germ cell-specific expression, and novel repeat elements present within this region are specifically required. These repeat sequences bind to a factor termed PACH1, the activity of which is upregulated in pachytene spermatocytes. We have also found that the expression of TATA binding protein (TBP) is highly induced at the transcriptional level in pachytene spermatocytes and round spermatids. This induction may reflect specialized requirements associated with male germ cell development. The aims of this proposal are: 1) To clone and characterize the PACH1 protein from rat spermatogenic cells using expression cloning approaches; 2) to fully analyze the cis-acting elements within the proenkephalin germ line promoter, with special focus on the repeat elements and potential regulatory sites lying downstream; and 3) to isolate and initially characterize the regulation of the TATA binding protein promoter during spermatogenesis. These studies will hopefully provide important new insight into the transcriptional regulatin of meiosis andhaploid cell formation, and may ultimately be relevant to male infertility and contraception.