Germ Cell Aging

描述(由申请人提供)：高龄父亲的年龄没有高龄母亲年龄那么广为人知，但父亲的年龄也会对生殖健康产生重大影响。大约5%的活着出生的人类后代患有遗传性疾病，其中大约20%是由种系新生突变引起的。一些常染色体显性遗传病与父亲的高龄有关。这些数据间接表明，男性生殖系中的突变频率随着年龄的增长而增加。调节突变频率增加的机制尚不清楚。我们的长期目标是识别和描述DNA完整性随着父亲年龄的增加而丧失的机制。为此，我们确定了一个小鼠模型，LACL转基因小鼠系，在从老年小鼠的生精细胞中恢复的LACL转基因中，显示出自发突变频率增加。我们建议使用LACL转基因小鼠模型来确定与父性高龄相关的分子机制。需要检验的假设是，维持男性生殖系DNA完整性的能力随着年龄的增长而下降。其具体目的是：1)评估不同年龄小鼠生精细胞核提取液的碱基切除修复活性；2)评估细胞凋亡在不同年龄雄性生殖系DNA完整性中的作用；3)确定不同年龄小鼠雄性生殖细胞DNA损伤的影响。这些研究的重点是了解被认为对维持遗传完整性有实质性贡献的途径，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涉及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.