Nuclear hormone receptor CHR3 is a critical regulator of all four larval molts of the nematode Caenorhabditis elegans

CHR3 (nhr-23, NF1F4), the homologue of Drosophila DHR3 and mammalian ROR/RZ R/RevErbA nuclear hormone receptors. is important for proper epidermal deve lopment and molting in the nematode Caenorhabditis elegans. Disruption of C HR3 (nhr-23) function leads to developmental changes, including incomplete molting and a short, fat (dumpy) phenotype. Here, we studied the role of CH R3 during larval development by using expression assays and RNA-mediated in terference. We show that the levels of expression of CHR3 (nhr-23) cycle du ring larval development and reduction of CHR3 function during each intermol t period result in defects at all subsequent molts. Assaying candidate gene expression in populations of animals treated with CHR3 (nhr-23) RNA-mediat ed interference has identified dpy-7 as a potential gene acting downstream of CHR3. These results define CHR3 as a critical regulator of all C. elegan s molts and begin to define the molecular pathway for its function.