Modeling human male infertility in mice

描述(申请人提供)：据估计，全世界有15%的夫妇受到不孕不育的影响。男性和女性对不孕不育的贡献大致相同。生育力的调节显然是复杂的，因为200多只基因敲除小鼠被描述为不孕不育的主要表型。尽管在老鼠模型上取得了进展，但人类男性不育的遗传原因几乎没有被识别出来。人类不孕不育的遗传原因研究进展缓慢可以归因于两个因素：1)特定基因的致因突变预计极其罕见；2)因果关系几乎不可能得到证明，因为传统的基于系谱的连锁分析不适用，因为不孕不育导致的后代缺乏。显然，需要新的方法来研究人类不孕不育的遗传原因。因此，我们提出，提高我们对人类男性不育的了解的最有意义的方式是利用敲门技术来产生并表征含有类似人类突变的小鼠。我们最近证明了TAF7L是一种X染色体编码的转录因子，在小鼠的精子生成中起着关键作用。为了确定TAF7L是否也可以在人类不育中发挥作用，我们对100名不育男性进行了筛查，并在一名精子数低的不育男性中发现了TAF7L的单一氨基酸替代(D？G)。我们的酵母遗传学研究表明，这种保守的天冬氨酸残基是TAF7功能所必需的，TAF7是TAF7L的酵母同源物。为了确定它是否在男性不育中起了作用，我们将在敲门小鼠中表达类似的突变，以便只表达突变的TAF7L。如果TAF7L的单点突变确实足以降低男性生育力，它将是第一个被发现在人类男性不育中起致病作用的单基因突变。这一发现的意义将是双重的。首先，TAF7L突变可能是母系遗传的，应该在遗传咨询中考虑：因为这是一个X连锁基因，一个单一的突变就会使男性不育。其次，由于TAF7L是一种转录因子，未来确定受该突变影响的蛋白质-蛋白质相互作用的研究可能为了解生殖细胞中独特的转录程序提供重要的见解。 与公共健康相关：在美国，不孕不育是一个普遍存在的生殖健康问题，影响着数百万夫妇。该项目的完成将确定人类一些男性不育病例的遗传原因。

DESCRIPTION (provided by applicant): An estimated 15% of couples are affected by infertility worldwide. Males and females contribute roughly equally to infertility. The regulation of fertility is clearly complex, as more than 200 knockout mice have been described to have infertility as a major phenotype. Despite progress made in mouse models, few genetic causes of male infertility in humans have been identified. The slow progress in the study of genetic causes of infertility in humans can be attributed to two factors: 1) causative mutations in a particular gene are expected to be extremely rare; and 2) causality is nearly impossible to prove, as traditional pedigree-based linkage analysis is not applicable, due to the lack of offspring caused by infertility. Clearly new approaches are required to investigate genetic causes of human infertility. Accordingly, we propose that the most informative way to advance our knowledge of human male infertility is to utilize knockin technology to generate and characterize mice that harbor the analogous human mutation. We have recently demonstrated that TAF7L, an X chromosome-encoded transcription factor, plays a critical role in sperm production in mice. To determine if TAF7L could also play a role in human infertility, we screened >100 infertile men and identified a single amino acid substitution (D?G) in TAF7L in an infertile man with low sperm count. Our yeast genetic studies demonstrated that this conserved aspartic residue is required for the function of TAF7, yeast homologue of TAF7L. To definitively determine if it plays a causative role in male infertility, we will express the analogous mutation in knockin mice such that only the mutated TAF7L is expressed. If a single point mutation in TAF7L is indeed sufficient to reduce male fertility, it will represent the first identified single gene mutation to play a causative role in male infertility in humans. The significance of such a finding will be two-fold. First, TAF7L mutations could be maternally inherited and should be considered in genetic counseling: since this is an X- linked gene, a single mutation would render males sterile. Second, as TAF7L is a transcription factor, future studies to determine protein-protein interactions affected by this mutation could provide significant insight into the unique transcription programs in germ cells. PUBLIC HEALTH RELEVANCE: Infertility is a widespread reproductive health problem affecting millions of couples in the US. Completion of this project will identify the genetic cause of some cases of male infertility in humans.