TRANSCRIPTIONAL CONTROL OF SPERMATOGENESIS

精子发生由发育阶段组成，在此阶段 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 由于生物化学特性的能力而导致的细胞分化 不连续的生精阶段。然而，这些机制 潜在的男性生殖细胞发育和相关阶段-和 对细胞特异性基因的表达知之甚少，尤其是在 转录水平。最近的研究表明， 转录因子CREMtau是病毒最后阶段的关键因子 精子发育，精子发生。然而，截然不同的 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 转基因小鼠对生精细胞的特异性研究 脑啡肽原启动子，它以阶段依赖的方式表达 粗线型精母细胞和圆形精母细胞的形态。一个 位于近端5‘-区的51个碱基序列对 生殖细胞特异性表达和存在新的重复元件 在这个区域内是特别需要的。这些重复 序列与一种称为PACH1的因子结合，其活性是 在粗线期精母细胞中表达上调。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的转录水平 精子细胞。这种归纳可能反映了专门的要求 与男性生殖细胞发育有关。这样做的目的是 建议：1)克隆和鉴定PACH1蛋白 使用表达克隆方法从大鼠生精细胞中分离； 2)全面分析脑啡肽原中的顺式作用元件 生殖系启动子，特别关注重复元件和 位于下游的潜在监管地点；以及3)隔离和 TATA结合蛋白调控的初步研究 精子发生过程中的启动子。这些研究有望 为转录调控提供了重要的新见解 减数分裂和单倍体细胞的形成，最终可能是相关的 到男性不育症和避孕。

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.