Control of Early Germline Development in C. elegans

描述(申请人提供)：生殖细胞负责物种的繁殖和永久存在，因此在发育中起着关键作用。我们正在利用遗传学、基因组学以及分子和生化方法相结合的方法，在模型系统秀丽线虫中研究保存生殖细胞永生的机制，并指导它们独特的发育程序。我们之前鉴定了四种线虫MES蛋白，它们是生殖细胞永生所必需的。MES-2、MES-3和MES-6在蠕虫体内构成染色质调节的多梳组，以复合体的形式运作，并参与在大多数生殖系发育过程中维持X染色体的沉默状态。MES-4结合常染色体，可能起到保护常染色体免受沉默的作用。MES系统在染色质中组蛋白尾部的修饰水平上运行。MES-2/3/6复合体催化组蛋白H3Lys27甲基化，从而抑制基因表达。该建议的目标是：a)阐明MES-3和MES-6以及可能是MES-6的替代伙伴如何影响MES-2对组蛋白甲基化的影响；b)检验我们关于MES-4也可使组蛋白甲基化的预测，并识别与MES-4一起工作的其他蛋白质；c)研究MES-4如何专门针对常染色体；d)确定一些其表达受MES-2/3/6和MES-4调控的基因；以及e)确定MES-2/3/6和MES-4如何相互作用以及与Synmuv类染色质调节剂的作用。染色质组织的动态调节是控制基因表达和发育的关键水平，而错误的调节被认为是导致疾病状态和癌症的原因。我们的研究将对理解染色质状态的控制、区分常染色体和性染色体的机制以及生殖细胞中特定的染色质需求做出重要贡献。

DESCRIPTION (provided by applicant): Germ cells are responsible for the fertility and perpetuation of species and thus serve a key role in development. We are investigating the mechanisms that preserve the immortality of germ cells and guide their unique developmental program, using a combination of genetics, genomics, and molecular and biochemical approaches in the model system Caenorhabditis elegans. We previously identified four C. elegans MES proteins as being required for germ cell immortality. MES-2, MES-3, and MES-6 constitute the Polycomb Group of chromatin regulators in worms, operate as a complex, and participate in maintaining the X chromosomes in a silenced state throughout most of germline development. MES-4 binds the autosomes and may function to protect them from silencing. The MES system operates at the level of modification of histone tails in chromatin. The MES-2/3/6 complex catalyzes methylation of histone H3 Lys27, which represses gene expression. The goals of this proposal are to: a) elucidate how MES-3 and MES-6 and perhaps an alternative partner to MES-6 influence histone methylation by MES-2, b) test our prediction that MES-4 also functions to methylate histones and identify other proteins that operate with MES-4, c) investigate how MES-4 is targeted specifically to the autosomes, d) identify some of the genes whose expression is regulated by MES-2/3/6 and MES-4, and e) determine how MES- 2/3/6 and MES-4 interface with each other and with the SynMuv class of chromatin regulators. The dynamic regulation of chromatin organization is a crucial level of control of gene expression and development, and misregulation is known to contribute to disease states and cancers. Our studies will make important contributions to understanding control of chromatin states, mechanisms for discriminating between the autosomes and the sex chromosomes, and specific chromatin requirements in germ cells.