Many types of sensory neurons contain modified cilia where sensory signal transduction occurs. We report that the C. elegans gene daf-19 encodes an RFX-type transcription factor that is expressed specifically in all ciliated sensory neurons. Loss of daf-19 function causes the absence of cilia, resulting in severe sensory defects. Several genes that function in all ciliated sensory neurons have an RFX target site in their promoters and require daf-19 function. Several other genes that function in subsets of ciliated sensory neurons do not have an RFX target site and are not daf-19 dependent. These results suggest that expression of the shared components of sensory cilia is activated by daf-19, whereas cell-type-specific expression occurs independently of daf-19.
