Do we need Y chromosome for successful reproduction?

描述(申请人提供)：男性不育症影响5%-10%的人口。男性不育的一个主要因素是Y染色体的缺失，但我们对Y染色体上特定基因的需求及其在精子产生/功能中的作用的了解仍然很差。Y染色体基因可能提供基本的生精功能，或者只是加强生精过程。我们的长期目标是在辅助生殖技术(ART)的背景下定义Y染色体编码基因在小鼠中的功能，作为模拟人类Y连锁不孕症的一种方式。我们已经确定只需要两个Y染色体基因，即睾丸决定基因Sry和精原细胞增殖因子Eif2s3y来产生能够参与辅助受精的雄配子。在初步数据中，我们显示Y补体仅限于Sry和Eif2s3y的男性精子发生停滞，不能产生成熟精子。前体单倍体生殖细胞(精子细胞)很少见，而且常常是异常的。然而，通过圆形精子细胞注射(ROSI)，我们成功地产生了活的、健康的和可生育的后代。这为患有广泛Y基因缺失和由此导致的无精子症的男性提供了一个希望。在这里，我们的具体目标是定义ART是否可以在没有这个最低Y基因贡献的情况下实现。我们将检验这样的假设，即Y染色体互补可以完全消除，同时保留功能性雄配子的产生。在目标1中，我们将测试Sry下游效应器Sox9的转基因激活是否会有效地取代Sry的功能，以及Sry到Sox9的替换是否会影响精子发生和生育，直接测试这些基因在成熟性腺中未知的功能。我们还将确定Eif2s3y的X编码同源物Eif2s3x是否可以取代Eif2s3y在精原细胞增殖中的作用。我们将建立和鉴定转Eif2s3x基因的小鼠，并评估过表达Eif2s3x能否挽救XOSry小鼠的精原细胞增殖停滞。在目标2中，我们将产生没有任何Y基因但有Eif2s3x过表达和Sox9转基因激活的男性，以及保留一个Y基因而另一个被替换的男性。我们将研究这些基因的存在如何影响精子发生的进程。我们还将测试这些男性的精子发生是否能够使生殖细胞发育成具有ART功能的生殖细胞，以及这些产生的后代是否正常。在目标3中，我们将尝试通过体内Eif2s3y基因转移和超声介导的基因传递来挽救成熟男性睾丸中的精原细胞停滞。我们的研究将促进人们对(1)性别决定的关键角色(Sry和Sox9)在成熟性腺中所起的作用；(2)性染色体基因(Eif2s3y和Eif2s3x)在精子发生启动中的作用；(3)广泛的Y基因缺失与成功的ART的兼容性。我们的结果应该转化为加强与Y染色体缺失相关的人类不孕症的治疗。好了！

DESCRIPTION (provided by applicant): Male infertility affects 5-10% of the population. A major factor associated with male infertility is Y chromosome deletions, yet our understanding of the requirement for specific genes on the Y chromosome and of their roles in sperm production/function is still poor. Y chromosome genes may provide essential spermatogenic functions or just potentiate the spermatogenic process. Our long-term goal is to define the function of Y chromosome encoded genes in mice in a context of assisted reproduction technologies (ART) as a way to model human Y- linked infertility cases. We have established that only two Y chromosome genes, testis determinant gene Sry and spermatogonial proliferation factor Eif2s3y are required for production of male gametes capable of participating in assisted fertilization. In Preliminary Data we show that males with a Y complement limited to Sry and Eif2s3y have spermatogenesis arrest and do not produce mature sperm. The precursor haploid germ cells (spermatids) are rare and often abnormal. Nevertheless, with round spermatid injection (ROSI) we succeeded in producing viable, healthy, and fertile progeny. This offers a promise to men with extensive Y gene loss and resulting azoospermia. Here, our specific goal is to define whether ART can be achieved even without this minimum Y gene contribution. We will test the hypothesis that the Y chromosome complement can be eliminated entirely while retaining production of functional male gametes. In Aim 1 we wil test if transgenic activation of Sox9, a downstream effector of Sry, will effectively replace Sry function and whether Sry-to-Sox9 replacement affects spermatogenesis and fertility, testing directly for the as yet unknown function of these genes in mature gonads. We will also establish if Eif2s3x, an X encoded homologue of Eif2s3y, can replace Eif2s3y function in spermatogonial proliferation. We will generate and characterize mice transgenic for Eif2s3x, and assess whether overexpression of Eif2s3x can rescue spermatogonial proliferation arrest in XOSry mice. In Aim 2, we will produce males without any Y genes but with overexpression of Eif2s3x and with transgenic activation of Sox9, as well as males with one Y gene retained and the other replaced. We will investigate how the presence of these genes affects spermatogenesis progression. We will also test if spermatogenesis in these males enables development of germ cells functional in ART, and whether such produced offspring are normal. In Aim 3, we will attempt to rescue spermatogonial arrest in testes of mature males with in vivo Eif2s3y gene transfer using novel 'active transgenesis' approach and ultrasound mediated gene delivery. Our studies will advance the understanding of (1) the roles that key players of sex determination (Sry and Sox9) play in mature gonads; (2) the roles of sex chromosome genes (Eif2s3y and Eif2s3x) in the initiation of spermatogenesis; and (3) the compatibility of extensive Y gene loss with successful ART. Our results should translate to enhance treatment of human infertility associated with Y chromosome deletions. !