AEC-associated p63 mutations lead to alternative splicing/protein stabilization of p63 and modulation of notch signaling

p63, the major regulator of epithelial development/differentiation, is mutated in human ectodermal dysplasias, such as ankyloblepharon, ectodermal dysplasia and clefting (AEC). We recently identified that p63α physically associated with mRNA processing/ splicing proteins. We previously showed that p63 mutations mapped to the sterile α-motif led to disruption of these interactions and modulated an aberrant splicing of keratinocyte growth factor receptor contributing into molecular mechanism underlying AEC phenotype. To further investigate the molecular mechanisms associated with AEC syndrome we established the cellular model for this disorder by stable introduction of mutated allele [L514F] of p63α into immortalized keratinocyte cells. We showed that mutated ΔNp63α mediated an aberrant splicing of its own p63 mRNA transcript, which in turn led to accumulation of proteasome-resistant C-terminal truncated p63. The truncated p63 failed to associate with the C-terminal domain of RNA polymerase II through SRA4 protein and, therefore affected keratinocyte proliferation, differentiation and survival and may strongly contribute to AEC phenotype.