AEC-Associated p63 Mutations Lead to Alternative Splicing/Protein Stabilization of p63 and Modulation of Notch Signaling

Abstract

P63, the major regulator of epithelial development/differentiation, is mutated in humanectodermal dysplasias, such as ankyloblepharon, ectodermal dysplasia and clefting (AEC). Werecently identified that p63? physically associated with mRNA processing/splicing proteins. Wepreviously showed that p63 mutations mapped to the sterile ?-motif led to disruption of theseinteractions and modulated an aberrant splicing of keratinocyte growth factor receptorcontributing into molecular mechanism underlying AEC phenotype.To further investigate the molecular mechanisms associated with AEC syndrome weestablished the cellular model for this disorder by stable introduction of mutated allele [L514F]of p63? into immortalized keratinocyte cells. We showed that mutated ?Np63? mediated anaberrant splicing of its own p63 mRNA transcript, which in turn led to accumulation ofproteasome-resistant C- terminal truncated p63. The truncated p63 failed to associate with theC-terminal domain of RNA polymerase II through SRA4 protein and, therefore affectedkeratinocyte proliferation, differentiation and survival and may strongly contribute to AECphenotype.