Analysis of checkpoint function in the germ line.

描述(申请人提供)：生殖细胞是经过有丝分裂、减数分裂和细胞分化以产生单倍体配子进行有性繁殖的特化细胞。人类生殖细胞中的错误是非常常见的，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、特纳综合征和克莱菲尔特综合征)。令人惊讶的是，在人类女性生殖细胞系中，检查点控制似乎效率较低；有人提出，这是与人类女性配子相关的缺陷频率高的原因之一。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在人类中与基因和途径的高度保守性来确定性别间胚系检查点功能差异的分子基础。为了解决这个重要的问题，我们将使用多管齐下的方法，依靠线虫的优势作为研究性别特定生殖系检查点功能的模型。为此，我们将比较雌性和雄性生殖细胞系中运行的监测机制，并通过分析已知的检查点突变、检查检查点蛋白的激活状态和通过识别新的检查点基因来确定雄性生殖细胞如何选择性地感知和应对增殖中的生殖细胞损伤。我们将通过监测检查点和凋亡蛋白的状态，以及当只有一种性别的减数分裂受损时，检查正反交后代的生存能力，确定雄性如何防止检查点激活的生殖系凋亡，以及这种缺失是否会导致非整倍体配子的高发生率。最后，我们将通过监测雄性X上染色体轴和联会复合体中心区成分的加载和拆解，探索染色质结构和检查点激活之间的关系，以及确定阻止单个X引发检查点反应的分子机制，确定如何在不引发检查点反应的情况下修复减数分裂诱导的单条X染色体上的双链断裂。对遗传易驯化的蠕虫系统中这一过程的理解可能有助于深入了解为什么人类雌性减数分裂的检查点控制效率较低，从而导致错误率较高。这些研究还将提供有关检查点控制的一般机制的新的和重要的信息，在这些过程中，缺陷是人类癌症发展的中心。 与公共卫生相关：生殖细胞形成卵子和精子以进行有性繁殖。我们的研究旨在了解错误是如何在这一过程中产生的。在人类中，这种错误会导致不孕不育、妊娠丢失和唐氏综合症等出生缺陷。

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.