Cleft palate‐associated gene, irf6, is required for cell adhesion in superficial epithelia of frog and zebrafish gastrula‐stage embryos

Sequence variation in the Interferon Regulatory Factor 6 (IRF6) gene contributes to non‐syndromic and syndromic versions of cleft lip and/or cleft palate (CL/P), but the role of IRF6 in normal craniofacial development is unknown. We detected expression of a zebrafish irf6 orthologue in various epithelia. Anti‐sense oligonucleotides targeting irf6 did not perturb early development, possibly because of high levels of maternally‐encoded Irf6. To target this maternal store, we built a potential dominant negative variant encoding only the Irf6 DNA binding domain (Irf6DBD). Zebrafish embryos injected with irf6DBD RNA die during gastrulation with a dramatic loss of cell adhesion; this phenotype is rescued by co‐injection of full length irf6 RNA. irf6 DBD ‐injected embryos display loss of keratin8 homologue expression and polymerized cortical actin in cells of the superficial epithelial enveloping layer (EVL). Mosaic analysis reveals effects of the Irf6DBD within EVL are cell autonomous. Depletion of maternal irf6 transcripts in Xenopus embryos also causes death at gastrulation with rupture of the superficial epithelial layer. These results argue for a conserved role for maternally encoded Irf6 in differentiation of cells of the superficial epithelium surrounding embryos. These findings may have relevance to the etiology of CL/P. Funded by March of Dimes and the U of I Genetics Program Training Grant.