Characterization of the Doublesex/MAB-3 transcription factor DMD-9 in Caenorhabditis elegans

DMD-9 is a Caenorhabditis elegans Doublesex/MAB-3 Domain transcription factor of unknown function. Single-cell transcriptomics revealed that dmd-9 is highly expressed in specific head sensory neurons, with lower levels detected in non-neuronal tissues (uterine cells and spermatheca). Here, we characterized endogenous dmd-9 expression and function in hermaphrodites and males to identify potential sexually dimorphic roles. In addition, we dissected the trans- and cis-regulatory mechanisms that control DMD-9 expression in neurons. Our results show that of the 22 DMD-9-expressing neuronal reporters we analyzed, only the neuropeptide-encoding flp-19 gene is cell-autonomously regulated by DMD-9. Further, we did not identify defects in behaviors mediated by DMD-9 expressing neurons in dmd-9 mutants. We found that dmd-9 expression in neurons is regulated by four neuronal fate regulatory TFs: ETS-5, EGL-13, CHE-1, and TTX-1. In conclusion, our study characterized the DMD-9 expression pattern and regulatory logic for its control. We found that, as with other DMD TFs, DMD-9 likely acts redundantly to control neuronal development and function.