Key Laboratory of Systems Health Science of Zhejiang Province, School of Life Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 310024, China.
State Key Laboratory of Molecular Biology, State Key Laboratory of Cell Biology, Shanghai Key Laboratory of Molecular Andrology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, 200031, China.
Sci China Life Sci. 2023 Jul;66(7):1459-1481. doi: 10.1007/s11427-023-2390-5. Epub 2023 Jun 15.
PIWI-clade proteins harness piRNAs of 24-33 nt in length. Of great puzzles are how PIWI-clade proteins incorporate piRNAs of different sizes and whether the size matters to PIWI/piRNA function. Here we report that a PIWI-Ins module unique in PIWI-clade proteins helps define the length of piRNAs. Deletion of PIWI-Ins in Miwi shifts MIWI to load with shorter piRNAs and causes spermiogenic failure in mice, demonstrating the functional importance of this regulatory module. Mechanistically, we show that longer piRNAs provide additional complementarity to target mRNAs, thereby enhancing the assembly of the MIWI/eIF3f/HuR super-complex for translational activation. Importantly, we identify a c.1108C>T (p.R370W) mutation of HIWI (human PIWIL1) in infertile men and demonstrate in Miwi knock-in mice that this genetic mutation impairs male fertility by altering the property of PIWI-Ins in selecting longer piRNAs. These findings reveal a critical role of PIWI-Ins-ensured longer piRNAs in fine-tuning MIWI/piRNA targeting capacity, proven essential for spermatid development and male fertility.
PIWI 蛋白家族利用 24-33 个核苷酸长的 piRNA。令人困惑的是，PIWI 蛋白家族如何结合不同大小的 piRNA，以及大小是否对 PIWI/piRNA 的功能有影响。在这里，我们报告说，PIWI 蛋白家族中特有的一个 PIWI-Ins 模块有助于确定 piRNA 的长度。Miwi 中的 PIWI-Ins 缺失会导致 MIWI 装载较短的 piRNA，并导致小鼠精子发生失败，这证明了这个调节模块的功能重要性。在机制上，我们表明较长的 piRNA 为靶 mRNA 提供了额外的互补性，从而增强了 MIWI/eIF3f/HuR 超级复合物的组装，以实现翻译激活。重要的是，我们在不育男性中发现了 HIWI（人 PIWIL1）的 c.1108C>T（p.R370W）突变，并在 Miwi 基因敲入小鼠中证明，这种遗传突变通过改变 PIWI-Ins 选择更长 piRNA 的特性，损害了男性生育能力。这些发现揭示了 PIWI-Ins 确保更长 piRNA 的关键作用，这对于微调 MIWI/piRNA 的靶向能力至关重要，这对于精子发生和男性生育能力是必不可少的。
