piRNA的发生和相关蛋白的研究进展

Research Progress on the Biogenesis and Related Proteins of piRNA

小RNA能在多水平(染色体构建、转录、翻译、RNA修饰和稳定等)对基因的表达进行调控。piRNA(Piwi-interacting RNA)主要参与生殖细胞的发育、转座子的沉默、异染色质的形成和生殖细胞DNA完整性的维持等过程,对遗传物质的稳定遗传具有重要意义。作为一类新型的小RNA,piRNA受到了广泛关注。从2006年发现至今,科研工作者对piRNA的发生和功能做了大量的推测、探索和验证。研究发现,piRNA主要分布在动物体睾丸的精原细胞和卵巢的卵母细胞内,果蝇卵巢体细胞(卵泡细胞)也存在少量的piRNA。piRNA在生殖细胞和体细胞内通过不同的途径产生,体细胞途径相对简单,生殖细胞途径主要通过"乒乓循环"实现。参与"乒乓循环"的3种Argonaute蛋白中,Piwi位于细胞核中,Ago3和Aub位于细胞质中,这一现象暗示piRNA可能在不同的区室内产生并发挥功能。piRNA 3′端的甲基化现象普遍存在,这对piRNA的稳定性具有重要意义,但并不是决定成熟piRNA长度的必需条件。piRNA相关蛋白质的已知功能是预测其产生过程和功能的重要线索,目前已有部分与piRNA产生和功能相关的蛋白质被发掘。另外,piRNA的调控网络比siRNA(Small interference RNA)和miRNA(microRNA)更加复杂,因此新的研究方法体系的出现加快了科研工作者对piRNA发生和功能的研究进程。本文主要就piRNA的生物发生、产生和功能相关蛋白及研究方法的研究进展做一简要论述。

Small RNAs regulate gene expression at multi-level, such as chromosome construction, transcription, translation, RNA modification and stability, piRNA （Piwi-interacting RNA） mainly participates in the process of development of germ cells, scilence of transposon, formation of heterochromatin, DNA integrity of germ cells, and so on. It is significant to steady heredity of hereditary substance. As a novel small RNA, piRNA has received wide attention. Since piRNA was found in 2006, considerable inference, quest and verification about the biogenesis and func- tion of piRNA have been carried out by researchers. Studies found that piRNA mainly distributed in the animal testes spermatogonial cells and ovarian oocytes, and there are also a small number of piRNAs in Drosophila ovarian somatic cells （follicle cells）, piRNA is generated by different ways in germ cells and somatic cells. The way in somatic cells is relatively simpler than that in germ cells, the way in germ cells is mainly through the ＂ping-pong cycle＂. In the ＂ping-pong cycle＂, Piwi locate in the nucleus, Ago3 and Aub locate in the cytoplasm. This phenomenon imply the piRNA may generate and play function in different compartments. The 3r end hyperm- ethylation of piRNA is widespread, which is significant to the stability of piRNA, but not the necessary conditions to determine the length of of mature piRNAs. Known fuctions of piRNA-re-lated proteins are important clues to predict the biogenesis and fuctions of piRNA. At present, some proteins related to piRNA biogenesis and function have been discovered, piRNA expression is limited to germline cells and its regulatory network is more complex than that of siRNA （small interference RNA） and miRNA （microRNA）. The emergence of novel methodology and system speed up the research process of piRNA biogenesis and function. This article is a brief overview focusing on piRNA biogenesis, produce and function related proteins and research methods.