线虫体内新piRNA研究

The Research of Caenorhabditis elegans New piRNAs

PIWI-interacting RNAs(piRNA)是一类內源性小RNA,负责抵御转座子和转基因对基因组的入侵.已发现1.6万多种piRNA,在piRNA上游存在保守序列,根据上游序列特征可以预测新的piRNA.将线虫同步化培养至L4时期,分别提取野生和prg-1突变样本中的小RNA,并对其进行高通量测序.基于piRNA上游保守序列特征,在野生线虫L4时期中,发现了967种新piRNA,这些新piRNA在prg-1突变后表达消失.新piRNA的基因座集中分布在四号染色体的2个piRNA簇内,首位碱基以U为主.与已发表的成虫发育时期的PRG-1免疫共沉淀数据比对,发现有153种piRNA存在于与PRG-1免疫沉淀的数据中.同时还发现一些只在野生线虫中表达的non-21nt小RNA,它们与已知piRNA的基因座相同,推测这些non-21nt小RNA可能是其piRNA前体加工的产物.总之,通过小RNA测序,在线虫中发现了一些新的piRNA.

PIWI-interacting RNAs （piRNA） are endogenous small RNAs （sRNA）, which play roles in resisting exogenous gene invasion and transposon mobility. More than 16 000 piRNAs are found in Caenorhabditis elegans, and the piRNA loci share a conserved upstream sequence. New piRNAs can be predicted based on its conserved upstream sequence. C. elegans are synchronized and small RNAs from wild type and prg-1 strains at L4 developmental period are sequenced through illumina technology. Basing on piRNA conserved uptream sequence, we find 967 new piRNAs expressed at IA period, and the expressions of new piRNAs disappear in prg-1 mutant. Most of new piRNAs are mapped into two piRNA clusters of Chromosome IV, and have an overwhelming bias for a 5＇ uracil. Compared to the published co-immunoprecipitation data from adult worms, over 100 new piRNAs can interact with PRG-1. However, some non-21nt long sRNAs, which also share the same loci with piRNAs, are also found in wide type worms. These non-21nt long sRNA may be co-products ofpiRNA precursors. Together, these results indicate that our sRNA sequencing identified many new piRNAs in C. elegans.