RNA-mediated Chromatin Regulation and Epigenetic Inheritance in C. elegans

描述（由申请人提供）：RNA干扰（RNAi）是一种进化上保守的、基于同源性的基因沉默机制，其中小干扰RNA（siRNA）导致宿主细胞中mRNA降解和/或异染色质形成。这种分子途径对于发育过渡和细胞对病原体挑战的反应至关重要。siRNA介导的异染色质反应，在本提案中被称为核RNAi，作为RNA水平的事件可以“反馈”以调节染色质结构和功能的表观遗传机制，已经引起了极大的兴趣。 这种现象最令人兴奋的方面是它通过有丝分裂或减数分裂细胞周期传递表观遗传信息的非凡能力。这在植物中RNA介导的DNA甲基化和裂殖酵母中RNA介导的转录沉默中研究得最好。然而，这一过程在多大程度上可以导致动物的跨代反应仍然是未知的。最明确的证据来自于C.优雅尽管在哺乳动物中的相关研究还远未得出结论，但异染色质反应和许多C。线虫RNAi组分也可以在人类中发现。在高度易处理的模式生物C中定义生殖细胞核RNAi途径的分子细节。elegans将为基于染色质的基因组调控和表观遗传的保守机制提供重要的见解。 这个模型中的以下基本问题必须通过实验来解决，以使该领域向前发展。生殖细胞核RNAi的天然靶点是什么？在生殖细胞发育过程中，靶基因的转录和沉默是如何协调的？表观遗传的机制是什么，维持沉默的目标基因在连续的生殖周期？解决这些基本问题将有助于我们预测染色质位点对靶向调控RNA的敏感性，这对我们将靶向染色质干预作为治疗工具的长期目标至关重要。我们将采用实验和计算相结合的方法来解决这些问题，在三个具体的目标：（1）全基因组的识别，表征，并在C核RNAi目标的分类。秀丽隐杆线虫生殖系(2)确定启动子在调节生殖细胞核RNAi中的作用。(3)确定异染色质在生殖细胞核RNAi介导的跨代基因沉默中的作用。 拟议的研究，探索基本但未知的领域，将对理解基因组与环境的相互作用以及与人类发育和疾病相关的表达状态的遗传产生深远的影响。

DESCRIPTION (provided by applicant): RNA interference (RNAi) is an evolutionarily conserved, homology-based gene silencing mechanism, in which small interfering RNAs (siRNAs) lead to mRNA degradation and/or heterochromatin formation in host cells. This molecular pathway is fundamentally important for development transition and cellular responses to pathogenic challenges. The siRNA-mediated heterochromatic response, which is referred to as nuclear RNAi in this proposal, has been of great interest as an epigenetic mechanism by which events at the RNA level can "feed back" to modulate chromatin structure and function. The most exciting aspect of this phenomenon is its remarkable ability to transmit epigenetic information through mitotic or meiotic cell cycles. This was best studied in RNA-mediated DNA methylation in plants and RNA-mediated transcriptional silencing in fission yeast. However, the extent to which this process can lead to a trans-generational response in animals remains largely unknown. The most definitive evidence came from the study of germline nuclear RNAi in C. elegans. Although related studies in mammals are far from conclusive, both the heterochromatin response and many of the C. elegans RNAi components can be found in humans as well. Defining molecular details of the germline nuclear RNAi pathway in a highly tractable model organism C. elegans will provide important insights into conserved mechanisms of chromatin-based genome regulation and epigenetic inheritance. The following fundamental questions in this model must be experimentally addressed for the field to move forward. What are the natural targets of germline nuclear RNAi? How are transcription and silencing of target genes coordinated during germline development? What are the mechanisms of epigenetic inheritance that maintain the silencing of target genes in successive reproductive cycles? Addressing these fundamental questions will help us to predict the sensitivity of a chromatin locus to a targeting regulatory RNA, which is critically important to our long-term goal of targete chromatin intervention as a therapeutic tool. We will employ a combination of experimental and computational approaches to address these questions in three specific aims: (1) Genome-wide identification, characterization, and classification of nuclear RNAi targets in the C. elegans germline. (2) Determine the role of promoters in regulating germline nuclear RNAi. (3) Determine the role of heterochromatin in trans- generational gene silencing mediated by germline nuclear RNAi. The proposed studies, which probe fundamental yet uncharted areas, will hold profound implications for understanding of genome-environment interaction and inheritance of expression states relevant to human development and disease.