Define piRNA biogenesis and function in mice

繁衍是生命的一个基本特征。动物通常需要生殖细胞的分化才能产生 配子。配子发生过程受到微妙的调节，其中的缺陷会导致生育问题 影响了15%的人类。Piwi相互作用RNA(PiRNAs)是最新发现且进化迅速的 动物体内的小核糖核酸的一类。在脊椎动物中，piRNAs几乎只在睾丸中表达，它们 对于精子发生来说是必不可少的。一些piRNAs通过引导PIWI蛋白沉默转座元件 序列的互补性；然而，人类、小鼠和公鸡也产生了一套不同的和丰富的 靶标未知的非重复的piRNA序列。我的长期目标是了解 PiRNAs及其在男性生育中的作用。PIRNA物种没有明显的保守性，而pIRNA 是异质性的：一个生物体携带数百万种不同的piRNA序列。这种多样性是由于它们 不寻常的生物发生。长的单链piRNA前体被切割成数千个片段，这些片段 片段被加载到PIWI蛋白中，成为piRNAs。这种碎片化，人们知之甚少， 将piRNA处理与其他RNA命运区分开来。我以前的工作定义了精确的转录单位 ，为分析它们的转录后加工和基因表达奠定了基础。 它们的功能。我进一步开发了新的方法和动物模型来克服长期存在的 PIRNA研究中的障碍。在未发表的工作中，我们发现核糖体似乎参与了piRNA。 生物发生，以及piRNAs调节精子表观基因组，包括RNAs和组蛋白。在这里，我建议 关注两个问题：1)什么原则指定一个序列成为piRNA？2)什么是 转座元件沉默以外的piRNAs在男性生殖中的作用？这项工作的发现 可能会导致发现男性生育和RNA生物学的新机制。

Reproduction is a fundamental feature of life. Animals usually require the differentiation of germ cells to create gametes. The gametogenesis process is delicately regulated, defects in which lead to fertility problems that impact 15% of humans. PIWI-interacting RNAs (piRNAs) are the most recently discovered and rapidly evolving class of small RNAs in animals. In vertebrates, piRNAs are almost exclusively expressed in testis, and they are essential for spermatogenesis. Some piRNAs guide PIWI proteins to silence transposable elements through sequence complementarity; humans, mice, and rooster, however, also produce a distinct and abundant set of non-repetitive piRNA sequences whose targets are unknown. My long-term goal is to understand the biology of piRNAs and their functions in male fertility. There is no obvious conservation of piRNA species, and piRNAs are heterogeneous: an organism carries millions of different piRNA sequences. The diversity is a result of their unusual biogenesis. Long single-stranded piRNA precursors are cleaved into thousands of snippets, and these fragments are loaded into PIWI proteins and become piRNAs. This fragmentation, which is poorly understood, distinguishes piRNA processing from other RNA fates. My previous work defined the precise transcription units of piRNA producing loci in mice, paving the way for the analysis of their post-transcriptional processing and their functions. I have further developed new methodologies and animal models to overcome longstanding roadblocks in piRNA research. In unpublished work, we found that ribosomes appear to participate in piRNA biogenesis, and that piRNAs act to regulate sperm epigenomes including RNAs and histones. Here, I propose to focus on two questions: 1) What principles designate a sequence to become a piRNA? 2) What is the function of piRNAs beyond transposable element silencing in male reproduction? The findings from this work may lead to the discovery of new mechanisms in male fertility and RNA biology.