The Yes-associated protein 1 stabilizes p73 by preventing Itch-mediated ubiquitination of p73

Upon DNA damage signaling, p73, a member of the p53 tumor suppressor family, accumulates to support transcription of downstream apoptotic genes. p73 interacts with Yes-associated protein 1 (Yap1) through its PPPY motif, and increases p73 transactivation of apoptotic genes. The ubiquitin E3 ligase Itch, like Yap1, interacts with p73. Given the fact that both Itch and Yap1 bind p73 via the PPPY motif, we hypothesized that Yap may also function to stabilize p73 by displacing Itch binding to p73. We show that the interaction of Yap1 and p73 was necessary for p73 stabilization. Yap1 competed with Itch for binding to p73, and prevented Itch-mediated ubiquitination of p73. Treatment of cells with cisplatin leads to an increase in p73 accumulation and induction of apoptosis, but both were dramatically reduced in the presence of Yap1 siRNA. Altogether, our findings attribute a central role to Yap1 in regulating p73 accumulation and function under DNA damage signaling.