Challenging the role of retinoic acid in meiotic initiation

项目总结/摘要 减数分裂是有性生殖所必需的，其专门的分子和细胞程序具有 在低等真核生物和哺乳动物中进行了深入研究。然而，在哺乳动物中， 有丝分裂的精原细胞进入减数分裂程序，称为减数分裂起始，很少受到关注。 减数分裂起始发生在减数分裂前期Ⅰ的前细线期， 复制它们DNA并为减数分裂重组和分离做准备。维甲酸（RA） 被认为是“减数分裂诱导物质”。在出生后的睾丸中，虽然它是明确要求的， 对于精原细胞的分化，我们令人兴奋的初步数据显示RA是在8.6天后， 用于减数分裂起始。因此，RA在减数分裂中的作用尚未得到适当的研究，真正的减数分裂- 诱发因素仍未确定。该提案代表了盖耶和 辛德勒实验室，谁将共同努力，以揭示真正的作用（S）为RA在减数分裂。在目标1中，我们将确定 在减数分裂的起始和发展过程中形成单倍体精子细胞对RA的特殊要求。 在目标2中，我们将采用一种新的同步精子发生的转基因小鼠模型， 在减数分裂开始之前和期间，基于荧光的数百万生殖细胞的分离。使用此 独特的资源，我们将定义和比较RA介导的基因表达的变化， 转录组（RNA丰度）、翻译组（翻译RNA）和蛋白质组（蛋白质丰度） 减数分裂起始期间的水平。这项工作的结果是确定了这种关键的新的调节剂。 过渡期和睾丸特异性蛋白质在前细线期精母细胞中上调， 男性避孕目标事实上，前细线期精母细胞是一种理想的细胞类型， 男性避孕药的发展，有两个原因：1）他们居住在血液睾丸屏障外 (BTB)，这是药物递送的重要屏障; 2）它们与精原干不同 细胞（SSC）池，因此可以被靶向而不会不可逆地损伤雄性生殖系。结果 从这个建议将是基础，以确定更广泛的机制之间的关系，RA和 减数分裂对男性生育力至关重要。

PROJECT SUMMARY/ABSTRACT Meiosis is essential for sexual reproduction, and its specialized molecular and cellular programs have been intensely studied in lower eukaryotes and mammals. In mammals, however, the transition from mitotic spermatogonia into the meiotic program, termed meiotic initiation, has received little attention. Meiotic initiation occurs during the preleptotene phase of meiotic prophase I, as these spermatocytes replicate their DNA and prepare for meiotic recombination and segregation. Retinoic acid (RA) has been proposed to serve as the ‘meiosis inducing substance.’ In the postnatal testis, although it is clearly required for spermatogonial differentiation, our exciting preliminary data reveals RA is dispensable 8.6 days later for meiotic initiation. Thus, the role of RA in meiosis has not been properly examined, and the true meiosis- inducing factor(s) remain undefined. This proposal represents a new collaboration between the Geyer and Schindler labs, who will work together to uncover the true role(s) for RA in meiosis. In Aim 1, we will identify the specific requirement for RA in initiation and progression through meiosis to form haploid spermatids. In Aim 2, we will employ a novel transgenic mouse model with synchronized spermatogenesis for fluorescence-based isolation of millions of germ cells prior to and during meiotic initiation. Using this unique resource, we will define and compare RA-mediated changes in gene expression at the transcriptome (RNA abundance), translatome (translating RNAs), and proteome (protein abundance) levels during meiotic initiation. The outcome of this work is identification of novel regulators of this critical transition, and testis-specific proteins that are upregulated in preleptotene spermatocytes will represent putative male contraceptive targets. Indeed, preleptotene spermatocytes represent an ideal cell type for male contraceptive drug development, for two reasons: 1) they reside outside the blood-testis-barrier (BTB), which is a significant barrier to drug delivery; and 2) they are distinct from the spermatogonial stem cell (SSC) pool, and thus can be targeted without irreversibly damaging the male germline. The results from this proposal will be foundational to defining the broader mechanistic relationship between RA and meiosis that are essential for male fertility.