Cell division cycle 25 (
cdc25) is an evolutionarily conserved phosphatase that promotes cell cycle progression. Among the four
cdc25 orthologs in Caenorhabditis elegans, we found that
cdc-25.4 mutant males failed to produce outcrossed progeny. This was not caused by defects in sperm development, but by defects in male mating behavior. The
cdc-25.4 mutant males showed various defects during male mating, including contact response, backing, turning, and vulva location. Aberrant turning behavior was the most prominent defect in the
cdc-25.4 mutant males. We also found that
cdc-25.4 is expressed in many neuronal cells throughout development. The turning defect in
cdc-25.4 mutant males was recovered by
cdc-25.4 transgenic expression in neuronal cells, suggesting that
cdc-25.4 functions in neurons for male mating. However, the neuronal morphology of
cdc-25.4 mutant males appeared to be normal, as examined with several neuronal markers. Also, RNAi depletion of
wee-1.3, a C. elegans ortholog of Wee1/Myt1 kinase, failed to suppress the mating defects of
cdc-25.4 mutant males. These findings suggest that, for successful male mating,
cdc-25.4 does not target cell cycles that are required for neuronal differentiation and development. Rather,
cdc-25.4 likely regulates non-canonical substrates in neuronal cells.