Sexual dimorphism of piRNA transcription and target silencing mechanisms in C. elegans

摘要 Piwi相互作用RNA（皮尔纳）途径通过保护生殖系基因组免受 移动的DNA元件。尽管有这种既定的模式，但我们的理解中仍存在一些关键的差距 皮尔纳机制，包括其生物起源和下游基因调控的性二态性 功能协调发展的我们发现，转录小细胞核的古老SNAPc（或SNPC）转录复合体， 剪接体的RNA（snRNA）在C.来驱动雄性和雌性 除了其在snRNA转录中的典型功能之外，它还具有特异性piRNA。在果蝇和人类中，SNPC 全复合物由SNPC-1、SNPC-3和SNPC-4亚基组成，每个亚基由单个基因编码。在 contrast，C.线虫表达了SNPC-1和SNPC-3的几种旁系同源物，我们认为这决定了特异性 三个不同的SNPC复合体特别是，根据我们公布的和初步的数据，我们假设， SNPC-1旁系同源物包含定义每个SNPC独特功能的主要特异性因子 snRNA或性别特异性皮尔纳转录的复合物。在本建议中，我们将首先研究如何 通过鉴定每个SNPC转录复合物识别的顺式调节元件来实现特异性 (Aim 1）。我们还将确定皮尔纳的特异性结构域、辅因子和亚细胞组装， snRNA SNPC复合物（目的2）。最后，我们将描述男性和女性的生物表型， 皮尔纳突变体，并利用这些见解来预测和验证性别特异性的内源性基因靶点。 piRNA。总的来说，这项研究将弥合我们对皮尔纳性别二态性理解的差距。 转录和基因靶向机制，确保适当的种系发育和强大的生殖 动物的能力。 1

Abstract The Piwi-interacting RNA (piRNA) pathway promotes animal fertility by protecting the germline genome against mobile DNA elements. Despite this well-established paradigm, several critical gaps remain in our understanding of piRNA mechanisms, including the sexual dimorphism of their biogenesis and downstream gene regulatory functions. We discovered that the ancient SNAPc (or SNPC) transcription complex that transcribes small nuclear RNAs (snRNAs) of the spliceosome has diversified in C. elegans to drive the expression of male- and female- specific piRNAs, in addition to its canonical function in snRNA transcription. In the fly and human, the SNPC holocomplex is composed of SNPC-1, SNPC-3, and SNPC-4 subunits, each encoded by a single gene. In contrast, C. elegans expresses several paralogs of SNPC-1 and SNPC-3 that we propose dictate the specificity of three distinct SNPC complexes. In particular, based on our published and preliminary data, we hypothesize that the SNPC-1 paralogs comprise the primary specificity factors that define the unique functions of each SNPC complex for either snRNA or sex-specific piRNA transcription. In this proposal, we will first investigate how this specificity is achieved by identifying the cis-regulatory elements recognized by each SNPC transcription complex (Aim 1). We will also determine the specificity domains, cofactors, and subcellular assembly of the piRNA and snRNA SNPC complexes (Aim 2). Finally, we will characterize the biological phenotypes of the male and female piRNA mutants and leverage these insights to predict and validate endogenous gene targets of sex-specific piRNAs. Collectively, this research will bridge the gaps in our understanding of sexual dimorphism in piRNA transcription and gene targeting mechanisms that ensure proper germline development and robust reproductive capacity of animals. 1