X Chromosomal Studies of Spermatogenic Failure

描述（由申请人提供）：该提案假定，对参与物种形成的快速进化基因的研究将为男性不育的人类分子遗传学提供重要见解。物种形成是两个种群在生殖上隔离的过程。在最近分化的物种之间，生殖隔离通常表现为雄性不育的形式。X染色体上快速进化的基因是这种生殖隔离的主要驱动力。我的初步研究已经确定了快速进化的X连锁基因，这些基因以大的、近乎完美的片段复制或扩增子的形式存在。我假设这些X-扩增子序列包含精子发生的关键基因，这些序列在一个物种内的快速进化可能导致男性不育。我将在人类和小鼠中进行研究来验证这一假设。在人类中，X染色体的所有扩增子将被准确测序以确定其基因组结构。在解析每个扩增子区域后，我将确定X-扩增子缺失与生精障碍（最常见的男性不育类型）显著相关的程度。为此，我将在500名生精障碍男性和500名对照人群中筛选缺失。为了检测人类X-扩增子基因是否在生精细胞中表达，我将进行X-扩增子基因的表达谱分析，以深入了解生精障碍的分子发病机制。在小鼠中，12%的X染色体由扩增子序列组成。两个X-扩增子区域特别令人感兴趣，因为它们代表了X染色体上进化最快的区域，并且与杂交小鼠的生精失败有关。因此，这两个X-扩增子区域代表了非常有前途的候选人，以研究精子发生功能的X-扩增子基因。为了测试这两个X-扩增子区域是否在生精失败中起作用，我将产生两个区域的独立靶向敲除。在小鼠中敲除X-扩增子区域提供了进行在人类中不可行的受控功能丧失和拯救实验的机会。在人类的DNA研究加上在小鼠中的X-扩增子基因的分子特征将是必不可少的，以促进我们的理解X-扩增子基因在人类精子发生和生殖功能。 公共卫生相关性：很少有遗传因素被确定来解释生精障碍的高发病率，这影响了1-2%的男性。了解X连锁基因在精子发生障碍中的位置和作用将有助于解释精子发生的分子机制和不育的重要原因。

DESCRIPTION (provided by applicant): This proposal posits that the study of rapidly evolving genes involved in speciation will provide significant insights into the human molecular genetics of male infertility. Speciation is the process by which two populations become reproductively isolated. Between recently diverged species, reproductive isolation typically manifests itself in the form of male infertility. Rapidly evolving genes on the X chromosome are primary drivers of this reproductive isolation. My preliminary studies have identified rapidly evolving X-linked genes which are harbored in large, near-perfect, segmental duplications, or amplicons. I hypothesize that these X-ampliconic sequences contain genes critical for spermatogenesis and that the rapid evolution of these sequences within a species can lead to male infertility. I will perform studies in humans and mice to test this hypothesis. In humans, all amplicons of the X chromosome will be accurately sequenced to determine their genomic architecture. Upon resolution of each ampliconic region, I will determine the extent to which X- ampliconic deletions are significantly associated with spermatogenic failure; the most common type of male infertility. To do this I will screen for deletions in a collection of 500 men with spermatogenic failure and 500 men from a control population. To test whether human X-ampliconic genes are expressed in spermatogenic cells, I will perform expression profiling of X-ampliconic genes to provide insight into the molecular pathogenesis of spermatogenic failure. In mice, 12% of the X chromosome is comprised of ampliconic sequences. Two X-ampliconic regions are of particular interest because they represent the most rapidly evolving regions of the X chromosome and have been linked to spermatogenic failure in hybrid mice. Thus, these two X-ampliconic regions represent highly promising candidates to study the spermatogenic functions of X-ampliconic genes. To test whether these two X-ampliconic regions have a role in spermatogenic failure, I will generate independent targeted knockouts of both regions. The knockout of X-ampliconic regions in mice offers opportunities to perform controlled loss-of-function and rescue experiments not feasible in humans. The DNA studies in humans coupled with molecular characterizations of X-ampliconic genes in mice will be essential to advance our understanding of X-ampliconic gene functions in human spermatogenesis and reproduction. PUBLIC HEALTH RELEVANCE: Few genetic factors have been identified to explain the high incidence of spermatogenic failure, which affects 1-2% of all men. Understanding the location and role of X-linked genes in spermatogenic failure will help explain molecular mechanisms of spermatogenesis and important causes of infertility.