MIWI and piRNA-mediated cleavage of messenger RNAs in mouse testes

Abstract

The piRNA machinery is known for its role in mediating epigenetic silencing of transposons and recent studies suggest that this function also involves piRNA-guided cleavage of transposon-derived transcripts. As many piRNAs also appear to have the capacity to target diverse mRNAs, this raises the intriguing possibility that piRNAs may act extensively as siRNAs to degrade specific mRNAs. To directly test this hypothesis, we compared mouse PIWI (MIWI)-associated piRNAs with experimentally identified cleaved mRNA fragments from mouse testes, observing cleavage sites that predominantly occur at position 10 from the 5' end of putatively targeting piRNAs. We also noted strong biases for U and A residues at nucleotide positions 1 and 10, respectively, in both mRNA fragments and piRNAs, the features that resemble the pattern of piRNA amplification by the 'ping-pong' cycle. Through CLIP-seq mapping of MIWI-RNA interactions and gene expression profiling, we found that many potential piRNA targeted mRNAs directly interact with MIWI, and show elevated expression in the testes of Miwi catalytic mutant mice. Reporter-based assays further revealed the importance of base-pairing between piRNAs and mRNA targets and the requirement for both the slicer activity and piRNA-loading ability of MIWI in piRNA-mediated target repression. Importantly, we demonstrated that proper turnover of certain key piRNA targets is essential for sperm formation. Together, these findings reveal the siRNA-like function of the piRNA machinery in mouse testes and its central requirement for male germ cell development and maturation.

Authors: Peng Zhang, Jun-Yan Kang, Lan-Tao Gou, Jiajia Wang, Yuanchao Xue, Geir Skogerboe, Peng Dai, Da-Wei Huang, Runsheng Chen
Corresponding authors: Xiang-Dong Fu, Mo-Fang Liu, Shunmin He

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The data in this article:

Predicted target sites
Functional cluster of target genes
Target genes essential for spermatogenesis
Sequences of synthesized oligonucleotides


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