Genetics 2018 08 25;209(4):1197-1224. Epub 2018 Jun 25.
Department of Genetics, School of Medicine, Washington University in St. Louis, Missouri 63110
A major event in germline development is the transition from stem/progenitor cells to entry into meiosis and gametogenesis. This transition requires downregulation of mitotic cell cycle activity and upregulation of processes associated with meiosis. We identify the SCF E3 ubiquitin-ligase complex as functioning to downregulate mitotic cell cycle protein levels including cyclin E, WAPL-1, and KNL-2 at meiotic entry and, independently, promoting homologous chromosome pairing as a positive regulator of the CHK-2 kinase. SCF is thus a novel regulator of meiotic entry, coordinating downregulation of mitotic cell cycle proteins and promoting homolog pairing. We further show that SCF functions redundantly, in parallel to the previously described GLD-1 and GLD-2 meiotic entry pathways, downstream of and inhibited by GLP-1 Notch signaling, which specifies the stem cell fate. Accordingly, employs three post-transcriptional pathways, SCF-mediated protein degradation, GLD-1-mediated translational repression, and GLD-2-mediated translational activation, to control and coordinate the initiation of meiotic development.