MSI‐1, a neural RNA‐binding protein, is involved in male mating behaviour in Caenorhabditis elegans

Neural RNA‐binding proteins are thought to play important roles in neural development and the functional regulation of postmitotic neurones by mediating post‐transcriptional gene regulation. RNA‐binding proteins belonging to the Musashi family are highly expressed in the nervous system; however, their roles are poorly understood. We identified a Caenorhabditis elegans Musashi homologue, MSI‐1, whose RNA‐recognition motifs show extensive similarity to those of Drosophila and vertebrate Musashi proteins. We isolated a msi‐1 mutant and found males with this mutation to have a mating defect. C. elegans male mating behaviour includes a distinct series of steps: response to contact, backing, turning, vulva location, spicule insertion, and sperm transfer. msi‐1 is required for the turning and vulva location steps. Like other Musashi family members, MSI‐1 is expressed specifically in neural cells, including male‐specific neurones required for turning and vulva location. However, msi‐1 was not expressed in proliferating neural progenitors in C. elegans , unlike the Musashi family genes in other systems. Our results suggest that msi‐1 is expressed specifically in postmitotic neurones in C. elegans . msi‐1 is required for full development of male mating behaviour, possibly through regulation of msi‐1 expressing neurones.