Germ Cell Aging

描述（由申请人提供）：父亲的高龄比母亲的高龄宣传得少，但父亲的年龄也会对生殖健康产生重大影响。大约5%的活产人类后代患有遗传疾病，其中大约20%是由于生殖系新生突变。几种常染色体显性遗传疾病与父亲高龄有关。这些数据间接表明，随着年龄的增长，男性生殖系的突变频率增加。介导突变频率增加的机制尚不清楚。我们的长期目标是确定和描述DNA完整性随着父亲年龄的增长而丢失的机制。为此，我们鉴定了一种小鼠模型，lacl转基因小鼠系，其表现出从老年小鼠的生精细胞中回收的lacl转基因的自发突变频率增加。我们建议使用lacl转基因小鼠模型，在我们的努力，以确定在先进的父亲年龄的分子机制。有待检验的假设是，维持男性生殖系DNA完整性的能力随着年龄的增长而下降。具体目标是：1）评估从不同年龄的小鼠获得的生精细胞制备的核提取物中的碱基切除修复活性，2）评估细胞凋亡在不同年龄的雄性生殖系DNA完整性中的作用，和3）确定诱导的DNA损伤在不同年龄的小鼠的雄性生殖细胞中的影响。这些研究的重点是了解被认为对维持遗传完整性有重大贡献的途径的贡献，即DNA碱基切除修复途径和细胞凋亡。这项研究将促进我们对男性生殖系完整性的基本机制的理解。

DESCRIPTION (provided by applicant): Advanced paternal age is less well publicized than advanced maternal age, but paternal age can also have a significant impact on reproductive health. Approximately 5% of liveborn human offspring have a genetic disorder and of these, approximately 20% are due to germline de novo mutations. Several autosomal dominant disorders are associated with advanced paternal age. These data indirectly indicate an increased mutant frequency in the male germline with age. The mechanisms mediating the increased mutant frequency are not understood. Our long-term goal is to identify and delineate the mechanisms by which DNA integrity is lost with advanced paternal age. Toward this end, we identified a mouse model, the lacl transgenic mouse line, that exhibits increased spontaneous mutant frequencies in the lacl transgene recovered from spermatogenic cells of older mice. We propose to use the lacl transgenic mouse model in our efforts to define the molecular mechanisms involved in advanced paternal age. The hypothesis to be tested is that the ability to maintain male germline DNA integrity declines with increased age. The specific aims are: 1) to assess base excision repair activity in nuclear extracts prepared from spermatogenic cells obtained from mice at various ages, 2) to assess the role of apoptosis in male germline DNA integrity at various ages, and 3) to determine the impact of induced DNA damage in male germ cells of mice at various ages. The studies are focused on understanding the contribution of pathways that are believed to contribute substantially to maintaining genetic integrity, namely the DNA base excision repair pathway and apoptosis. This study will advance our understanding of the fundamental mechanisms involved in male germline integrity.