中科院上海生物化学与细胞生物学研究所刘默芳、武汉大学周宇、复旦大学施惠娟等研究人员合作揭示，MIWI/piRNA在小鼠精子发生过程中的翻译激活功能。该项研究成果发表在2019年12月12日出版的《细胞》上。
研究人员表示，精子发生是一个高度编排的发育过程，在此过程中染色质浓缩使转录与翻译脱钩。生精mRNA较早转录并以翻译惰性状态保存，直到需要翻译时为止。然而，目前仍不清楚在精子发生过程中这种抑制的mRNA如何被激活。 研究人员以前曾报道过，MIWI/piRNA机制负责后期精子发生过程中的mRNA消除，以准备生产精子。
研究人员出乎意料地发现，同样的机制还负责激活一部分生精mRNA的翻译，以协调向精子的形态转化。此类作用需要piRNA与3'UTR中的靶标mRNA进行特异性碱基配对相互作用，从而通过与富含AU的顺式作用元件偶联来激活翻译，从而使MIWI/piRNA/eIF3f/HuR超复合体以发育阶段特异性方式形成。这些发现揭示了piRNA系统在翻译激活中的关键作用，研究人员证明了精子细胞发育在功能上是必需的。
附：英文原文
Title: A Translation-Activating Function of MIWI/piRNA during Mouse Spermiogenesis
Author: Peng Dai, Xin Wang, Lan-Tao Gou, Zhi-Tong Li, Ze Wen, Zong-Gui Chen, Min-Min Hua, Ai Zhong, Lingbo Wang, Haiyang Su, Huida Wan, Kun Qian, Lujian Liao, Jinsong Li, Bin Tian, Dangsheng Li, Xiang-Dong Fu, Hui-Juan Shi, Yu Zhou, Mo-Fang Liu
Issue&Volume: 2019/12/12
Abstract: Spermiogenesis is a highly orchestrated developmental process during which chromatincondensation decouples transcription from translation. Spermiogenic mRNAs are transcribedearlier and stored in a translationally inert state until needed for translation;however, it remains largely unclear how such repressed mRNAs become activated duringspermiogenesis. We previously reported that the MIWI/piRNA machinery is responsiblefor mRNA elimination during late spermiogenesis in preparation for spermatozoa production.Here we unexpectedly discover that the same machinery is also responsible for activatingtranslation of a subset of spermiogenic mRNAs to coordinate with morphological transformationinto spermatozoa. Such action requires specific base-pairing interactions of piRNAswith target mRNAs in their 3′ UTRs, which activates translation through coupling withcis-acting AU-rich elements to nucleate the formation of a MIWI/piRNA/eIF3f/HuR super-complexin a developmental stage-specific manner. These findings reveal a critical role ofthe piRNA system in translation activation, which we show is functionally requiredfor spermatid development.
DOI: 10.1016/j.cell.2019.11.022
Source: https://www.cell.com/cell/fulltext/S0092-8674(19)31278-4