Arrestin-3 scaffolds multiple MAP3Ks driving stress-induced JNK3 activation and cell death.

Non-visual arrestin-3 (a.k.a. {beta}-arrestin-2) functions as a scaffold facilitating the activation of c-Jun N-terminal kinases (JNKs), an important pathway regulating cell fate. Here, we demonstrate that arrestin-3 scaffolds not only previously identified ASK1, but facilitates signaling by several MAP3Ks, including ZAK, ZAK{beta}, MEKK1, and TAK1. We identified ZAK (sterile alpha motif and leucine zipper-containing kinase) as the predominant MAP3K mediating arrestin-3-dependent JNK3 signaling and chemotherapy drug-induced cell death in HEK293 cells. We also showed that a 16-residue-long arrestin-3-derived peptide binds ZAK and fulfills the scaffolding function of full-length arrestin-3, sensitizing cells to death induced by chemotherapy drugs. These findings demonstrate that arrestin-3 is a versatile facilitator of stress signaling and suggest that functional peptide mimics can be used therapeutically to facilitate drug-induced death of cancer cells.