Drosha Regulates Oogenesis and microRNAs Germline Autonomously and Non autonomously in C. elegans

Small non-coding RNAs regulate multiple aspects of development including germ cell development. The microRNA pathway genes Dicer, Drosha and Pasha have been shown to regulate oocyte meiotic maturation in C. elegans. However, Dicer controls oocyte meiotic maturation through endo-siRNAs, rather than microRNAs. A repertoire of Drosha-dependent oocyte-expressed microRNAs were identified which regulate various aspects of oogenesis but not oocyte meiotic maturation. These data lead to the following models: (a) microRNAs function redundantly to regulate oocyte meiotic maturation, (b) Drosha and microRNAs function germline non-autonomously to regulate meiotic maturation. We investigated these models and observed that Drosha regulates oocyte meiotic maturation in a germline non-autonomous manner. Additionally, we uncovered a role for Drosha in regulating pachytene progression and oocyte development in a germline autonomous manner through miR-35 family and miR-51 respectively. Interestingly we also find that though Drosha-dependent oocyte-expressed microRNAs, miR-61 and miR-72, are sufficient to regulate pachytene progression and oocyte development respectively, they are generated in a germline non-autonomous manner. Collectively these data reveal a Drosha-dependent microRNA circuit, which coordinates oocyte development germline autonomously as well as through soma-germline communication.