Yale Stem Cell Center, Yale University School of Medicine, New Haven, Connecticut 06511, USA.
Annu Rev Cell Dev Biol. 2009;25:355-76. doi: 10.1146/annurev.cellbio.24.110707.175327.
The evolutionarily conserved Argonaute/PIWI (AGO/PIWI, also known as PAZ-PIWI domain or PPD) family of proteins is crucial for the biogenesis and function of small noncoding RNAs (ncRNAs). This family can be divided into AGO and PIWI subfamilies. The AGO proteins are ubiquitously present in diverse tissues. They bind to small interfering RNAs (siRNAs) and microRNAs (miRNAs). In contrast, the PIWI proteins are predominantly present in the germline and associate with a novel class of small RNAs known as PIWI-interacting RNAs (piRNAs). Tens of thousands of piRNA species, typically 24-32 nucleotide (nt) long, have been found in mammals, zebrafish, and Drosophila. Most piRNAs appear to be generated from a small number of long single-stranded RNA precursors that are often encoded by repetitive intergenic sequences in the genome. PIWI proteins play crucial roles during germline development and gametogenesis of many metazoan species, from germline determination and germline stem cell (GSC) maintenance to meiosis, spermiogenesis, and transposon silencing. These diverse functions may involve piRNAs and may be achieved via novel mechanisms of epigenetic and posttranscriptional regulation.
进化保守的 Argonaute/PIWI（AGO/PIWI，也称为 PAZ-PIWI 结构域或 PPD）蛋白家族对于小非编码 RNA（ncRNA）的生物发生和功能至关重要。该家族可分为 AGO 和 PIWI 亚家族。AGO 蛋白广泛存在于各种组织中。它们与小干扰 RNA（siRNA）和 microRNA（miRNA）结合。相比之下，PIWI 蛋白主要存在于生殖系中，并与一类新的小 RNA 即 PIWI 相互作用 RNA（piRNA）相关联。在哺乳动物、斑马鱼和果蝇中发现了数万种 piRNA 物种，通常长 24-32 个核苷酸（nt）。大多数 piRNA 似乎是由少数长的单链 RNA 前体产生的，这些前体通常由基因组中重复的基因间序列编码。PIWI 蛋白在许多后生动物物种的生殖系发育和配子发生中发挥着关键作用，从生殖系决定和生殖干细胞（GSC）维持到减数分裂、精子发生和转座子沉默。这些不同的功能可能涉及 piRNA，并可能通过表观遗传和转录后调控的新机制来实现。
