Wellcome Trust Cancer Research UK Gurdon Institute, Department of Genetics, University of Cambridge, Cambridge CB2 1QN, United Kingdom;
Genes Dev. 2014 Apr 1;28(7):783-96. doi: 10.1101/gad.238105.114.
Piwi-interacting RNAs (piRNA) are small regulatory RNAs with essential roles in maintaining genome integrity in animals and protists. Most Caenorhabditis elegans piRNAs are transcribed from two genomic clusters that likely contain thousands of individual transcription units; however, their biogenesis is not understood. Here we identify and characterize prde-1 (piRNA silencing-defective) as the first essential C. elegans piRNA biogenesis gene. Analysis of prde-1 provides the first direct evidence that piRNA precursors are 28- to 29-nucleotide (nt) RNAs initiating 2 nt upstream of mature piRNAs. PRDE-1 is a nuclear germline-expressed protein that localizes to chromosome IV. PRDE-1 is required specifically for the production of piRNA precursors from genomic loci containing an 8-nt upstream motif, the Ruby motif. The expression of a second class of motif-independent piRNAs is unaffected in prde-1 mutants. We exploited this finding to determine the targets of the motif-independent class of piRNAs. Together, our data provide new insights into both the biogenesis and function of piRNAs in gene regulation.
Piwi 相互作用 RNA (piRNA) 是一类小的调节 RNA，在动物和原生生物中维持基因组完整性方面具有重要作用。大多数秀丽隐杆线虫的 piRNA 是从两个基因组簇转录而来的，这些基因组簇可能包含数千个单独的转录单位；然而，它们的生物发生过程尚不清楚。在这里，我们鉴定并表征了 prde-1（piRNA 沉默缺陷）作为第一个必需的秀丽隐杆线虫 piRNA 生物发生基因。对 prde-1 的分析提供了第一个直接证据，证明 piRNA 前体是 28-29 个核苷酸 (nt) 的 RNA，起始于成熟 piRNA 的上游 2 个 nt。PRDE-1 是一种核生殖细胞表达的蛋白，定位于染色体 IV。PRDE-1 专门用于从包含 8-nt 上游基序（Ruby 基序）的基因组位点产生 piRNA 前体。在 prde-1 突变体中，第二类不依赖于基序的 piRNAs 的表达不受影响。我们利用这一发现来确定不依赖于基序的 piRNA 类的靶标。总之，我们的数据为 piRNA 在基因调控中的生物发生和功能提供了新的见解。
