GLP-1/Notch signaling promotes germ cell proliferation by inhibiting the activity of two redundant pathways that promote meiotic development, the GLD-1/NOS-3 pathway and the GLD-2/GLD-3 pathway. The GLD-1 pathway likely acts, at least in part, to promote meiotic development by translationally repressing proliferation promoting gene products while the GLD-2 pathway likely acts, at least in part, to promote the translation of meiotic gene products. Genetic data indicates that a third redundant pathway exists that promotes meiotic development. The mog genes (
mog-1, -4, -5 & -6) were originally identified in the Kimble lab based on their masculinized hermaphrodite germline phenotype. Genetic experiments indicate that the mog genes function in the proliferation vs. meiotic development decision; for example
mog-6 is a tumorous enhancer of weak
glp-1 gf mutations and is synthetic tumorous with
gld-3. Our studies of the MOGs have lead to three conclusions. First, the MOGs appear to function downstream of GLP-1 signaling to promote meiotic development. This based on the finding that, for example, the
gld-3 mog-6;
glp-1 null triple mutant is tumorous. Surprisingly, the
gld-2 mog-6;
glp-1 null triple mutant has a Glp premature meiotic entry phenotype. (These results indicate that GLD-3 must have a function in addition to acting with GLD-2 to promote meiotic development.) Second, the MOGs may function, at least in part, in the third meiotic entry pathway. This is based on (a) the MOGs functioning outside of the GLD-2/GLD-3 pathways (e.g.
gld-2;
mog-6 is synthetic tumorous); (b) the MOGs acting, at least in part, outside of the GLD-1 pathway (e.g.
gld-1;
mog-6 males display overproliferation phenotypes) and (c) the MOGs promoting meiotic development in the absence of the GLD-1 and GLD-2 pathways (e.g.
gld-1 gld-2 displays some meiotic development while
gld-1 gld-2;
mog-6 is completely tumorous). Third, the MOGs appear to function redundantly with GLD-2 to promote GLD-1 accumulation (e.g.
gld-2 fog-3;
mog-6 fails to accumulate GLD-1). Thus, the MOGs appear to act by at least two mechanisms to promote meiotic development downstream of GLP-1 signaling; functioning in the third pathway and promoting GLD-1 accumulation.