Editors' ChoiceCell Migration

Oxidative inhibition of cofilin

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Sci. Signal.  09 Jun 2015:
Vol. 8, Issue 380, pp. ec153
DOI: 10.1126/scisignal.aac7260

Hydrogen peroxide (H2O2) is a reactive oxygen species that acts as a second messenger by oxidizing thiol groups, such as those in cysteine residues of proteins. H2O2 stimulates cell migration and adhesion in several contexts, including the immune response and cancer cell metastasis. Using a genetically encoded fluorescent H2O2 sensor, Cameron et al. found that H2O2 was more abundant in the leading edge protrusions of migrating human metastatic breast cancer MDAMB231 cells than in stationary cells or in the cell bodies of migrating cells. Western blotting of extracts from cells treated with dimedone, a chemical that labels oxidized cysteine residues, revealed increased oxidation of many proteins in migrating versus stationary cells. Mass spectrometry revealed that Cys139 and Cys147 of the actin-depolymerizing protein cofilin were labeled with dimedone, and immunoblotting showed that dimedone-labeled cofilin was more abundant in extracts from migrating cells compared with stationary cells. Oxidation converts the thiol group of cysteine residues to sulfenic or sulfinic acid, and molecular modeling predicted that oxidation of Cys139 and Cys147 to sulfinic acid would reduce the abilty of cofilin to bind actin. A mutant version of cofilin in which both Cys139 and Cys147 were changed to Asp (C139D/C147D), which mimics the size and charge of sulfinic acid, exhibited reduced binding to G-actin. Recombinant wild-type cofilin bound to F-actin in vitro, but binding was reduced when cofilin was pretreated with H2O2 prior to incubation with F-actin. Mutating both Cys139 and Cys147 to Ala (C139A/C147A) prevented this H2O2-induced reduction in F-actin binding. In vitro assays also demonstrated that H2O2 reduced the ability of wild-type cofilin to sever F-actin. MDAMB231 cells expressing the oxidation-resistant C139A/C147A cofilin showed reduced adhesion and impaired directionality, but no change in migration speed, compared with controls. Thus, cysteine oxidation at the leading edge helps maintain directional migration by inhibiting the ability of cofilin to sever actin filaments.

J. M. Cameron, M. Gabrielsen, Y. H. Chim, J. Munro, E. J. McGhee, D. Sumpton, P. Eaton, K. I. Anderson, H. Yin, M. F. Olson, Polarized cell motility induces hydrogen peroxide to inhibit cofilin via cysteine oxidation. Curr. Biol. 25, 1520–1525 (2015). [PubMed]