Small Silencing RNA Function in Genome Maintenance and Gamete Development

项目一。皮尔纳在表观遗传中的功能。 私家侦探克雷格·梅洛 项目摘要 达尔文认识到，自然选择的进化需要两个不证自明但又完全神秘的因素。 生物学机制：（i）遗传的特性，使得后代共享父母的特征，以及（ii） 变异的来源，这样新的遗传特征，适应，就可以出现。孟德尔的发现 遗传学和DNA的结构和性质似乎解决了这些谜团，创造了广泛持有的 以DNA为中心的遗传观。然而，从芭芭拉·麦克林托克的杂色经典作品开始， 玉米，一个不断发展的表观遗传学领域已经开始揭示RNA和染色质如何有助于 传承最近，我们发现一种称为Piwi途径的RNAi相关的小RNA途径， 在C.秀丽隐杆线虫生殖系值得注意的是， 该途径涉及皮尔纳信号，其不仅构成基因沉默的记忆（和执行器）， 还涉及所表达的生殖系基因的表观遗传记忆（和保护器）。PIWI Argonautes和他们的 小RNA辅因子（piRNA）是动物生殖系发育的保守调节因子。piRNA途径 突变体表现出胚胎致死性和部分或完全的生育缺陷，其特征是 增殖的生殖系和转座因子的激活。虽然piRNA在转座子中的作用 尽管基因沉默已被充分确立，但piRNA如何促进生殖细胞发育和功能尚不清楚。这里 我们提出了一系列遗传、生物化学和生物信息学研究，以进一步表征和理解：1） PIWI/皮尔纳复合物靶向的分子机制和结果，2）个体特异性 PIWI和3）皮尔纳途径的表观遗传功能。从实验室平行项目中获得的见解 Drs. Theurkauf和Zamore将通过翁实验室基于信息学的模型构建来指导这一分析 并为探测皮尔纳活性和下游功能提供了新的工具和方法。 相关性 这些研究将推进我们对皮尔纳在生育力和表观遗传中的功能的基本理解， 并指导我们理解相关途径如何保护人类基因组，维持体细胞 细胞，并促进生殖细胞的多能性和永生。

Project I. piRNA function in epigenetic inheritance. Craig Mello, P.I. Project summary Darwin recognized that evolution by natural selection required two self-evident but entirely mysterious biological mechanisms: (i) a property of inheritance such that offspring share features of parents, and (ii) a source of variation so that novel inherited features, adaptations, can arise. The discovery of Mendelian genetics and of the structure and properties of DNA seemed to solve these mysteries, creating the widely held DNA-centric view of inheritance. However, beginning with Barbara McClintock's classic work on variegation in maize, a growing field of epigenetics has begun to reveal how RNA and chromatin can contribute to inheritance. Recently, we have shown that an RNAi-related small-RNA pathway called the Piwi pathway can initiate a very stable transgenerational mode of epigenetic silencing in the C. elegans germline. Remarkably, this pathway involves piRNA signals that constitute not only a memory (and enforcer) of gene silencing but also involves an epigenetic memory (and protector) of expressed germline genes. PIWI Argonautes and their small RNA cofactors (piRNAs) are conserved regulators of germline development in animals. piRNA-pathway mutants exhibit embryonic lethality and partial or complete deficits in fertility, characterized by under- proliferated germlines and activation of transposable elements. While the role of piRNAs in transposon silencing is well established, how piRNAs promote germ cell development and function is not understood. Here we propose a set of genetic, biochemical and bioinformatic studies to further characterize and understand: 1) the molecular mechanisms and outcomes of targeting by PIWI/piRNA complexes, 2) the specificity of individual PIWIs, and 3) the epigenetic functions of piRNA pathways. Insights from parallel projects in the laboratories of Drs. Theurkauf and Zamore, with informatics-based model building by the Weng lab, will inform this analysis and provide new tools and methods for probing piRNA activities and downstream functions. Relevance These studies will advance our basic understanding of piRNA function in fertility and epigenetic inheritance, and should guide our understanding of how related pathways protect the human genome, maintain somatic cells, and promote the pluripotency and immortality of germ cells.