Centre for Immunity, Infection and Evolution, Ashworth Laboratories, University of Edinburgh, West Mains Road, Edinburgh EH9 3JT, UK.
Biochem Soc Trans. 2013 Aug;41(4):881-6. doi: 10.1042/BST20130086.
In the last decade, many diverse RNAi (RNA interference) pathways have been discovered that mediate gene silencing at epigenetic, transcriptional and post-transcriptional levels. The diversity of RNAi pathways is inherently linked to the evolution of Ago (Argonaute) proteins, the central protein component of RISCs (RNA-induced silencing complexes). An increasing number of diverse Agos have been identified in different species. The functions of most of these proteins are not yet known, but they are generally assumed to play roles in development, genome stability and/or protection against viruses. Recent research in the nematode Caenorhabditis elegans has expanded the breadth of RNAi functions to include transgenerational epigenetic memory and, possibly, environmental sensing. These functions are inherently linked to the production of secondary siRNAs (small interfering RNAs) that bind to members of a clade of WAGOs (worm-specific Agos). In the present article, we review briefly what is known about the evolution and function of Ago proteins in eukaryotes, including the expansion of WAGOs in nematodes. We postulate that the rapid evolution of WAGOs enables the exceptional functional plasticity of nematodes, including their capacity for parasitism.
在过去的十年中，已经发现了许多不同的 RNAi（RNA 干扰）途径，这些途径可以在表观遗传、转录和转录后水平上介导基因沉默。RNAi 途径的多样性与 Ago（Argonaute）蛋白的进化密切相关，Ago 蛋白是 RISCs（RNA 诱导的沉默复合物）的核心蛋白成分。在不同的物种中已经鉴定出越来越多的不同的 Ago。这些蛋白质的大多数功能尚不清楚，但它们通常被认为在发育、基因组稳定性和/或抵御病毒方面发挥作用。最近在线虫秀丽隐杆线虫中的研究扩展了 RNAi 功能的范围，包括跨代表观遗传记忆，并且可能还包括环境感应。这些功能与产生二级 siRNAs（小干扰 RNA）密切相关，二级 siRNAs 与 WAGO （蠕虫特异性 Ago）簇的成员结合。在本文中，我们简要回顾了真核生物 Ago 蛋白的进化和功能，包括线虫中 WAGO 的扩展。我们假设 WAGO 的快速进化使线虫具有非凡的功能可塑性，包括它们的寄生能力。
