Age and molecular mechanisms contributing to aneuploidy in oocytes

描述（由申请人提供）：非整倍体的增加是人类女性生育能力显著下降的主要原因，从35岁开始；女性卵子非整倍体的发生率在40岁左右增加到35%，而且可能会更高，因为导致自然流产的非整倍体往往没有被发现。非整倍体是妊娠失败的主要原因，当发育到足月时，是发育障碍和智力迟钝的加重来源。大多数与母亲年龄增加相关的非整倍体是由于减数分裂期间发生的非分离和减数分裂错误。值得注意的是，导致年龄相关的非整倍体增加的潜在分子机制尚不清楚。我们之前的研究结果表明，纺锤体组装检查点（SAC）和着丝点功能的缺陷可能是导致年龄相关的非整倍体增加的原因。SAC是一种途径，通过阻断后期的开始，直到所有染色体都正确地附着在纺锤体上，从而防止分离错误。利用小鼠作为模型系统和活体卵母细胞的成像，Specific Aim 1将检验卵母细胞SAC的稳健性随着年龄的增长而下降的假设。另一个防止错误的过程是调节着丝点和纺锤体微管之间的连接，从而使纺锤体与染色体正确连接。我们的表达谱也揭示了参与染色体形成的着丝点蛋白的表达变化。特异性目的2将检查染色体组成和纺锤体微管-着丝点正确附着的分子机制，并验证这些机制在老年雌性卵母细胞中受损的假设。Specific Aim 3将测试从我们的表达谱研究中鉴定出的特定着丝粒和着丝粒蛋白是否需要在心肌梗死期间进行准确的染色体分离。本应用程序中提出的实验结果将提供大量关于分子基础的信息，这些分子基础是年龄相关的非整倍体发生率增加的基础，以及准确染色体分离所需的基本机制。这些发现可能表明，实验干预可以减轻从老年妇女获得的卵母细胞变成非整倍体的倾向。公共卫生相关性：拟议的研究将提供关于与母亲年龄相关的非整倍体增加的分子机制的新信息。这些研究的结果可能会对人类不孕症的治疗和辅助生殖技术产生影响。

DESCRIPTION (provided by applicant): An increase in aneuploidy is a major cause for the marked decline in human female fertility commencing 35 years-of-age; the incidence of aneuploidy in eggs from women increases to 35% around 40 years-of-age, and is likely to be even higher because aneuploidy leading to a spontaneous abortion is frequently not recognized. Aneuploidy is a leading cause of pregnancy loss, and when development goes to term, an aggravating source of developmental disabilities and mental retardation. Most aneuplodies associated with increased maternal age are due to non-disjunction and meiotic errors that occur during meiosis. Remarkably, the underlying molecular mechanisms that lead to the age-associated increase in aneuploidy are poorly understood. Results of our previous studies suggest that defects in the spindle assembly checkpoint (SAC) and kinetochore function are likely causes for the age-associated increase in aneuploidy. The SAC is one pathway that prevents segregation errors by blocking the onset of anaphase until all chromosomes make proper attachments to the spindle. Using mouse as a model system and imaging of live individual oocytes, Specific Aim 1 will test the hypothesis that the robustness of the SAC in oocytes decreases with age. Another process that prevents errors is regulation of connections between kinetochores and spindle microtubules that results in a spindle with chromosomes correctly attached. Our expression profiling also reveals changes in expression of kinetochore proteins involved in chromosome congression. Specific Aim 2 will examine chromosome congression and molecular mechanisms that underlie correct spindle microtubule-kinetochore attachment, and test the hypothesis that these mechanisms are compromised in oocytes obtained from old females. Specific Aim 3 will test whether specific centromere and kinetochore proteins identified from our expression profiling studies are required for accurate chromosome segregation during MI. Results of experiments proposed in this application will provide a plethora of information regarding molecular bases that underlie the age-associated increase in the incidence of aneuploidy, as well as basic mechanisms required for accurate chromosome segregation. Such findings may suggest experimental interventions that could alleviate the propensity of oocytes obtained from older women to become aneuploid. PUBLIC HEALTH RELEVANCE: The proposed studies will provide new information regarding molecular mechanisms that underlie the maternal age-associated increase in aneuploidy. The results of these studies will likely impact on the treatment of human infertility and assisted reproduction technologies.