Mechanisms of dsRNA-induced gene silencing

描述（由申请人提供）：所有生物的基因组都被称为转座子的寄生遗传元件定殖。如果不加以控制，这些有可能在每一代产生大量的累积突变。此外，在一些模型系统中，即使是单个转座子的活性也会导致不育和生殖细胞损失。这就产生了巨大的进化压力，迫使我们进化出区分转座子和内源基因的机制，并选择性地沉默转座子。在上一次资助期间，我们发现了一个基于RNA的小免疫系统，由Piwi蛋白和piRNA组成，可以保护生殖细胞基因组免受基因组寄生虫的活动。该系统包含遗传编码的抗性（皮尔纳簇）和适应性成分（乒乓循环），该适应性成分将反应集中在活性元素上。在这个应用程序中，我们建议加深我们对皮尔纳途径的组成的理解，阐明它如何区分自我（内源基因）和非自我（转座子），并探索遗传和选择性沉默自私DNA的机制。虽然建议的研究集中在果蝇，我们研究的机制，是保守的整个后生动物。 公共卫生相关性：该应用程序的目标是进一步了解小RNA的生物学影响。小RNA是影响从癌症到神经变性的疾病状态的基因调节剂。它们作为理解正常和异常生物过程的工具，并可能通过作为新一代治疗药物的基础而改变临床实践。

DESCRIPTION (provided by applicant): The genomes of all living things have been colonized by parasitic genetic elements known as transposons. If left unchecked, these have the potential to produce a significant and accumulating load of mutations at each generation. Moreover, the activity of even a single transposon can cause sterility and germ cell loss in some model systems. This creates tremendous evolutionary pressure to evolve mechanisms to discriminate transposons from endogenous genes and to selectively silence the former. During the last grant period, we uncovered a small RNA-based immune system, comprising of Piwi proteins and piRNAs, that guards germ cell genomes against the activity of genomic parasites. This system contains both genetically encoded resistance (piRNA clusters) and an adaptive component (the ping-pong cycle) that focuses responses toward active elements. In this application, we propose to deepen our understanding of the composition of the piRNA pathway, to elucidate how it discriminates self (endogenous genes) from non-self (transposons), and to probe the mechanisms by which it heritably and selectively silences selfish DNA. Though proposed studies focus on Drosophila, the mechanisms, which we study, are conserved throughout metazoans. PUBLIC HEALTH RELEVANCE: The goal of this application is to further understand the biological impacts of small RNAs. Small RNAs are gene regulators that impact disease states ranging from cancer to neurodegeneration. They serve as tools for understanding normal and aberrant biological processes and will perhaps transform clinical practice by serving as the basis for a new generation of therapeutic agents.