Analysis of checkpoint function in the germ line.

描述（由申请人提供）：生殖细胞是经过有丝分裂增殖、减数分裂和细胞分化产生单倍体配子进行有性生殖的特化细胞。人类生殖细胞的错误是相当普遍的，并导致高频率的自然流产和非整倍体后代（例如，唐氏综合症，特纳和克兰费尔特综合症）。令人惊讶的是，检查点控制在人类女性生殖系中似乎效率较低；有人提出，这是与人类女性配子相关的高频率缺陷的原因之一。在这里，我们建议利用秀丽隐杆线虫生殖系独特的结构组织、该系统的分子遗传学以及与人类基因和途径的高度保守性来确定两性之间差异生殖系检查点功能的分子基础。为了解决这一重要问题，我们将采用多管齐下的方法，依靠秀丽隐杆线虫的优势作为研究性别特异性种系检查点功能的模型。为此，我们将比较在雌性和雄性生殖系中运行的监视机制，并通过分析已知的检查点突变体，检查检查点蛋白的激活状态，并通过识别新的检查点基因，确定雄性如何选择性地感知和响应增殖生殖细胞中的损伤。我们将通过监测检查点和凋亡蛋白的状态，以及当减数分裂仅在一种性别中受损时，检查互惠杂交后代的生存能力，来确定雄性如何阻止检查点激活的种系凋亡，以及这种缺失是否导致非整倍体配子的高发生率。最后，我们将确定减数分裂诱导的双链断裂是如何在单个X染色体上修复而不引发检查点反应的，方法是监测雄性X染色体上染色体轴和突触复合体的中心区域组分的装载和拆卸，探索染色质结构与检查点激活之间的关系，并确定阻止单个X引发检查点反应的分子机制。在遗传上易于处理的蠕虫系统中，对这一过程的理解可能有助于了解为什么人类女性减数分裂的检查点控制效率较低，从而导致错误率高。这些研究还将为检查点控制的一般机制提供新的和重要的信息，在这些机制中，缺陷是人类癌症发展的核心。

DESCRIPTION (provided by applicant): Germ cells are specialized cells that undergo mitotic proliferation followed by meiosis and cellular differentiation to generate haploid gametes for sexual reproduction. Errors in human germ cells are quite common and result in a high frequency of spontaneous abortions and aneuploid progeny (e.g., Down, Turner and Klinefelter's Syndrome). Surprisingly, checkpoint control appears to be less efficient in the human female germ line; it has been proposed that this is one reason for the high frequency of defects associated with human female gametes. Here, we propose to take advantage of the unique structural organization of the Caenorhabditis elegans germ line, the molecular genetics of the system, and the high degree of conservation with genes and pathways in humans to determine the molecular basis for differential germ-line checkpoint function between the sexes. To tackle this important problem, we will use a multi-pronged approach that relies on the strengths of C. elegans as a model for investigating sex-specific germ-line checkpoint function. To that end, we will compare the surveillance mechanisms in operation in the female and male germ lines, and determine how males selectively sense and respond to damage in proliferating germ cells by analyzing known checkpoint mutants, examining the activation state of checkpoint proteins, and by identifying new checkpoint genes. We will determine how males prevent checkpoint-activated germ-line apoptosis and whether such absence leads to a high incidence of aneuploid gametes by monitoring the status of checkpoint and apoptotic proteins and examining the viability of progeny from reciprocal crosses when meiosis is impaired in only one of the sexes. Finally, we will determine how meiotically-induced double strand breaks are repaired on a single X chromosome without eliciting a checkpoint response by monitoring the loading and disassembly of chromosomal axis and central region components of the synaptonemal complex on the male X, probing the relationship between chromatin structure and checkpoint activation, and identifying the molecular machinery that prevents the single X from eliciting a checkpoint response. An understanding of this process in the genetically tractable worm system may provide insight into why human female meiosis has less efficient checkpoint control, contributing to the high rate of errors. These studies will also provide new and important information on general mechanisms of checkpoint control, processes in which defects are central to the developmental of human cancers. PUBLIC HEALTH RELEVANCE: Germ cells form egg and sperm for sexual reproduction. Our studies are aimed at understanding how errors arise during this process. In humans, such errors result in infertility, pregnancy loss and birth defects such as Down Syndrome.