Elucidation of the mechanism by which β‐arrestin‐1 regulates LIM kinase 1 (773.3)

Abstract

Elucidation of the mechanism by which β‐arrestin‐1 regulates LIM kinase 1 Kyu Lee, Alice Lin, Rashid Awan, and Kathryn Defea. Department of Biochemistry and Molecular Biology, University of California, Riverside, Riverside, California 92521 β‐ arrestins are multifunctional proteins which can mediate termination of G‐protein signaling and internalization of receptor upon binding to G‐protein‐coupled receptor (GPCR). Also, β‐arrestins can transduce signals to downstream targets in G‐protein independent signaling manner. Protease‐activated receptor‐2 (PAR2), G‐protein couple receptor, can be activated by proteolytic cleavage of N‐terminus, which exposes a tethered ligand (SLIGRL/SLIGKV,human/mouse) leading to Gαq signaling while simultaneously promote activation of Cofilin, actin filament severing protein, through β‐arrestins. Cofilin, which can sever the existing filaments and create many barbed ends for the rapid changes, is necessary for chemotaxis or cell migration. Cofilin can be regulated by LIM kinase (LIMK), inactivating by phosphorylation at Ser 3, and regulated by chronophin (CIN), activating by dephosphorylation at Ser 3. We have previously shown that β‐arrestin can interact with cofilin, LIMK, and CIN and regulate their activities. However, the mechanism how β‐arrestin‐1 (β1) can interact and regulate LIMK and cofilin upon PAR‐2 activation has not been investigated explicitly. Here, using multiple recombinant β1 truncations in sandwich immunoassays, in vitro kinase assays and co‐immunoprecipitation, we demonstrate that the specific regions in β1 scaffold and regulate the kinase activity of LIMK. Thus, this study furthers characterize the interaction between β1 and LIMK.