RFX2 is broadly required for ciliogenesis during vertebrate development

In C. elegans, the RFX (Daf19) transcription factor is a major regulator of ciliogenesis, controlling the expression of the many essential genes required for making cilia. In vertebrates, however, there are seven RFX genes have been identified. Bioinformatic analysis suggests that Rfx2 is the closest homologue of the Daf19. We therefore hypothesize that Rfx2 broadly controls ciliogenesis during vertebrate development. Indeed, here we show that Rfx2 in Xenopus is expressed preferentially in ciliated tissues, including neural tube, gastrocoel roof plate, epidermal multi-ciliated cells, otic vesicles, and kidneys. Knockdown of Rfx2 results in cilia-defective embryonic phenotypes and fewer or truncated cilia are observed in Rfx2 morphants. These results indicate that Rfx2 is broadly required for ciliogenesis in vertebrates. Furthermore, we show that Rfx2 is essential for expression of several ciliogenic genes, including TTC25, which we show here is required for ciliogenesis, HH signaling, and left/right patterning.