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Control of Meiotic Spindle Assembly in Mammalian Oocytes

哺乳动物卵母细胞减数分裂纺锤体组装的控制

基本信息

批准号：
8232463
负责人：
MARIA M. VIVEIROS
金额：
$ 44.55万
依托单位：
UNIVERSITY OF GEORGIA
依托单位国家：
美国
项目类别：
财政年份：
2012
资助国家：
美国
起止时间：
2012-04-01 至 2017-03-31
项目状态：
已结题

项目摘要

DESCRIPTION (provided by applicant): An abnormal chromosome number (aneuploidy) in developing embryos is the leading genetic cause of congenital birth defects and pregnancy loss in women. The majority of aneuploidies are attributed to errors in chromosome segregation that occur during meiotic division in oocytes, and increase significantly with maternal age. Chromosome segregation is critically dependent on assembly of the microtubule spindle apparatus as well as the establishment of stable chromosome-microtubule interactions. Disrupted spindles in oocytes from older women have been recognized for some time, yet the underlying causes remain unknown. Notably, our recent studies in mice demonstrate that disruption of spindle stability can promote chromosome segregation errors, which are not fully resolved -despite activation of the spindle assembly checkpoint (SAC) in oocytes. These findings indicate that defects in spindle stability, which do not promote complete meiotic arrest, likely pose a potentially significant risk in contributing to aneuploidy. Yet, despite its fundamental importance, regulation of spindle assembly/organization in mammalian oocytes is poorly understood. In current studies, we identified a critical role for pericentrin in stable meiotic spindle formation. The experiments outlined in this proposal address the underlying mechanisms of meiotic spindle formation in oocytes, and will test whether these mechanisms are disrupted with increasing maternal age. In Aim 1, we propose to test the function of pericentrin by generating an oocyte-conditional knockdown mouse using an established transgenic RNAi approach. This unique genetic model will be used to test two central questions. (1) Does pericentrin plays a key role in regulating oocyte MTOC organization and function? (2) Is MTOC-mediated microtubule nucleation essential for stable meiotic spindle formation in oocytes? In Aim 2, we propose to determine whether oocytes from older female mice exhibit defects in meiotic spindle organization and/or stability. Importantly we will test if these defects are attributable to alterations in MTOC function or spindle microtubule stability. Knowledge gained from these studies will provide critical insight into the basis of human aneuploidy and provide improved parameters for the analysis of oocyte quality. PUBLIC HEALTH RELEVANCE: An abnormal chromosome number (aneuploidy) in developing embryos is the leading genetic cause of congenital birth defects and pregnancy loss in women. The majority of aneuploidies are attributed to chromosome segregation errors that occur during meiotic division in oocytes, and increase significantly with maternal age. Accurate chromosome segregation is critically dependent on assembly of the microtubule spindle apparatus and the establishment of stable chromosome-microtubule interactions. In this study we propose to (1) assess the underlying mechanisms of meiotic spindle formation and (2) test the hypothesis that defects in meiotic spindle stability contribute to age-associated aneuploidy in oocytes.

描述（由申请人提供）：发育中的胚胎染色体数目异常（非整倍体）是女性先天性出生缺陷和妊娠流产的主要遗传原因。大多数非整倍体是由于卵母细胞减数分裂时发生的染色体分离错误，并随着母亲年龄的增加而显著增加。染色体分离严重依赖于微管纺锤体装置的组装以及稳定的染色体-微管相互作用的建立。老年妇女的卵母细胞纺锤体紊乱已经被发现有一段时间了，但其根本原因尚不清楚。值得注意的是，我们最近在小鼠身上的研究表明，纺锤体稳定性的破坏可以促进染色体分离错误，尽管在卵母细胞中激活了纺锤体组装检查点（SAC），但这并没有完全解决。这些发现表明纺锤体稳定性的缺陷，不会促进减数分裂完全停止，可能会对非整倍性造成潜在的重大风险。然而，尽管其具有基本的重要性，但对哺乳动物卵母细胞纺锤体组装/组织的调节知之甚少。在目前的研究中，我们确定了中心蛋白在稳定减数分裂纺锤体形成中的关键作用。本研究将探讨卵母细胞减数分裂纺锤体形成的潜在机制，并将测试这些机制是否随着母亲年龄的增加而被破坏。在Aim 1中，我们提出通过使用已建立的转基因RNAi方法产生卵母细胞条件敲低小鼠来测试心心包蛋白的功能。这种独特的遗传模型将用于测试两个核心问题。(1)周心蛋白是否在调节卵母细胞MTOC组织和功能中起关键作用？(2) mtoc介导的微管成核对卵母细胞稳定的减数分裂纺锤体形成至关重要吗？在Aim 2中，我们提出确定老年雌性小鼠的卵母细胞是否在减数分裂纺锤体组织和/或稳定性方面存在缺陷。重要的是，我们将测试这些缺陷是否归因于MTOC功能或纺锤体微管稳定性的改变。从这些研究中获得的知识将为人类非整倍体的基础提供关键的见解，并为卵母细胞质量的分析提供改进的参数。