Paip1, an effective stimulator of translation initation, is targeted by WWP2 for ubiquitination and degradation.

Poly(A)-binding protein-interacting protein 1 (Paip1) stimulates translational initiation by inducing the circularization of mRNA. However, the mechanisms underlying Paip1 regulation, particularly its protein stability, are still unclear. Here we show that the E6AP carboxyl terminus (HECT)-type ubiquitin ligase WW domain-containing protein 2 (WWP2), a homolog of HECT-type ubiquitin ligase WWP1, ...
interacts with and targets Paip1 for ubiquitination and proteasomal degradation. Mapping of the region, including the WW domain of WWP2, revealed the interaction between WWP2 and the PABP-binding motif 2 (PAM2) of Paip1. The two consecutive PxxY motifs in PAM2 are required for WWP2-mediated ubiquitination and degradation. Furthermore, ectopic expression of WWP2 decreases translational stimulatory activity with the degradation of Paip1. We therefore provide the evidence that the stability of Paip1 can be regulated by ubiquitin-mediated degradation; thus, highlighting the importance of WWP2 as a suppressor of translation.
Mol. Cell. Biol.
Date: Sep. 29, 2014
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