Department of Molecular Biology, Massachusetts General Hospital, Department of Genetics, Harvard Medical School, Boston, MA 02114, USA.
Proc Natl Acad Sci U S A. 2011 Jan 25;108(4):1201-8. doi: 10.1073/pnas.1018695108. Epub 2011 Jan 18.
Argonaute-associated siRNAs and Piwi-associated piRNAs have overlapping roles in silencing mobile genetic elements in animals. In Caenorhabditis elegans, mutator (mut) class genes mediate siRNA-guided repression of transposons as well as exogenous RNAi, but their roles in endogenous RNA silencing pathways are not well-understood. To characterize the endogenous small RNAs dependent on mut class genes, small RNA populations from a null allele of mut-16 as well as a regulatory mut-16(mg461) allele that disables only somatic RNAi were subjected to deep sequencing. Additionally, each of the mut class genes was tested for a requirement in 26G siRNA pathways. The results indicate that mut-16 is an essential factor in multiple endogenous germline and somatic siRNA pathways involving several distinct Argonautes and RNA-dependent RNA polymerases. The results also reveal essential roles for mut-2 and mut-7 in the ERGO-1 class 26G siRNA pathway and less critical roles for mut-8, mut-14, and mut-15. We show that transposons are hypersusceptible to mut-16-dependent silencing and identify a requirement for the siRNA machinery in piRNA biogenesis from Tc1 transposons. We also show that the soma-specific mut-16(mg461) mutant allele is present in multiple C. elegans laboratory strains.
Argonaute 相关的 siRNA 和 Piwi 相关的 piRNA 在沉默动物中的移动遗传元件方面具有重叠作用。在秀丽隐杆线虫中，突变（mut）类基因介导转座子的 siRNA 指导抑制以及外源 RNAi，但它们在内源性 RNA 沉默途径中的作用尚未得到很好的理解。为了表征依赖 mut 类基因的内源性小 RNA，对 mut-16 缺失突变体以及仅使体细胞 RNAi 失活的调节型 mut-16(mg461)突变体的小 RNA 群体进行了深度测序。此外，还测试了每个 mut 类基因在 26G siRNA 途径中的必需性。结果表明，mut-16 是涉及几种不同的 Argonaute 和 RNA 依赖性 RNA 聚合酶的多个内源性生殖系和体细胞 siRNA 途径的必需因素。结果还揭示了 mut-2 和 mut-7 在 ERGO-1 类 26G siRNA 途径中的必需作用，以及 mut-8、mut-14 和 mut-15 的作用不那么关键。我们表明转座子对依赖 mut-16 的沉默高度敏感，并确定了 siRNA 机制在 Tc1 转座子产生 piRNA 中的作用。我们还表明，在多个秀丽隐杆线虫实验室品系中都存在体特异性 mut-16(mg461)突变体等位基因。
