GSE124047
RNAseq E15.5 mouse skin WT, Irf6 KO, Ripk4 KD, and Irf6 S413A.S424A knockin
The integrity of the mammalian epidermis is essential for organism survival, and it depends on a balance of proliferation and differentiation in the resident stem cell population. The kinase Ripk4 and the transcription factor Irf6 are mutated in severe developmental syndromes in humans, and mice lacking these genes display epidermal hyperproliferation and soft tissue fusions, resulting in neonatal lethality. However, the mechanism by which these genes control epidermal differentiation in vivo is unknown. By generating various mouse knock-out and knock-in strains we demonstrate that in vivo the role of Ripk4 in development is dependent on its kinase activity, Ripk4 and Irf6 function cell autonomously in the epidermis,Ripk4 and Irf6 lie on a linear pathway and phosphorylation of Irf6 on Serine413 and Serine424 is essential to prime it for activation. This priming then allows Ripk4 to phosphorylate Irf6 on Serine90, which ensures Irf6 activation. We then use RNA-seq, ChIP-seq and ATAC-seq analysis to define the global transcriptional targets of Irf6 in epidermal differentiation. Collectively, our results explain how Ripk4 activates Irf6, and how this pathway ensures epidermal differentiation and a functional barrier. This is crucial for understanding the etiology of developmental syndromes that are characterized by orofacial, skin and genital abnormalities. Overall design: RNA was extracted from kinase dead skin of E15.5 mouse embryos for the following genotypes - wildtype (WT), Irf6 knockout (Irf6KO), Ripk4 knockout (Ripk4KD), and Irf6 S413A.S424A knockin (Irf6.S413A.S424A).