Requirement of Irf6 and Esrp1/2 in frontonasal and palatal epithelium to regulate craniofacial and palate morphogenesis in mouse and zebrafish

Orofacial clefts are among the most common congenital structural anomalies. From genome-wide association studies over a decade ago to more recent whole-genome sequencing projects of orofacial cleft cohorts, human geneticists have identified several cleft-associated genetic loci, where the transcription factor Interferon regulatory factor 6 (IRF6) continues to be one of the most commonly associated genes. Irf6 has been found to regulate epithelial/periderm differentiation and in mice, adhesion defects are thought to prevent elevation of the palatal shelves, leading to cleft in the secondary palate. Epithelial splicing regulatory factors 1 and 2 (Esrp1, Esrp2) are also important in embryonic epithelial differentiation and palate development. Esrp2 and its homolog Esrp1 are regulators of RNA splicing that are specifically expressed in the epithelium. Esrp1/2 knockout mice exhibit bilateral cleft of the lip and primary palate, as well as a secondary palate cleft. Here, we analyze the Irf6 and Esrp1/2 mutant mouse models together to elucidate the gene expression details of Irf6 and Esrp1/2 during embryogenesis, comparative morphologies and genetic epistasis between these genes. Further, we generated zebrafish orofacial cleft models of irf6 and esrp1/2 and delineated developmental similarities and differences between mouse and zebrafish craniofacial biology. This work highlights the relative strengths of the mouse and zebrafish models for investigating the morphogenetic mechanisms of orofacial clefts and contributes new insights into the function of Irf6 and Esrp1/2 during palatogenesis.