Altered Sumoylation of p63α Contributes to the Split-Hand/Foot Malformation Phenotype

Abstract

p63 mutations have been identified in several developmental abnormalities, including splithand/foot malformation (SHFM). In this study, we demonstrate that the C-terminal domain of p63αassociates with the E2 ubiquitin conjugating enzyme, Ubc9. A p63α mutation, Q634X, whichnaturally occurs in SHFM modulated the interaction of p63α with Ubc9 in yeast genetic assay.Furthermore, Ubc9 catalyzed the conjugation of p63α with small ubiquitin modifier-1 (SUMO-1),which covalently modified p63α in vitro and in vivo at two positions (K549E and K637E), eachsituated in a SUMO-1 modification consensus site (?KXD/E). In addition, p63? mutations (K549Eand K637E) abolished sumoylation of p63α, dramatically activated transactivation properties ofTAp63α, and inhibited the dominant-negative effect of ΔNp63α. These p63? mutations also affectedthe transcriptional regulation of gene targets involved in bone and tooth development (e.g., RUNX2and MINT) and therefore might contribute to the molecular mechanisms underlying the SHFMphenotype.