Transcriptome-wide analyses using HITS-CLIP and RNA-Seq reveals the role of MOV10L1 in piRNA biogenesis. Mus musculus

We identified MOV10L1 bound RNAs at a transcriptome wide level, by using high throughput sequencing after crosslinking and immunoprecipitation (HITS-CLIP, also known as CLIP-Seq). We reveal that MOV10L1 specifically binds the piRNA precursor transcripts before Piwi proteins. For this study we also generated RNA-seq data from whole testis and enriched pachytene spermatocyte and round spermatid populations, from WT testis and testis with postnatal conditonal disruption of the Mov10l1 gene. Additonally we performed HITS-CLIP for the Piwi protein Mili using the same Mov10l1 mutant testis, and we analyzed it in parallel with Mili WT CLIP and the aforementioned RNA-Seq data. This analysis revealed lack of production of intermediate piRNA processing fragments in Mov10l1 mutants. Our results support a model whereby MOV10L1, a putative RNA helicase, funnels the single stranded piRNA precursor to the endonuclease that catalyzes the first cleavage step of the long piRNA precursor transript, thereby initiating piRNA processing.