Pharmaceutical Sciences Faculty Publications

Oxidant-induced apoptosis is mediated by oxidation of the actin-regulatory protein cofilin.

Document Type

Article

Publication Date

10-1-2009

Journal Title

Nature Cell Biology

ISSN

1476-4679

Volume

11

Issue

10

First Page

1241

Last Page

1246

DOI

10.1038/ncb1968

PubMed ID

19734890

PubMed Central® ID

PMC3393095

Abstract

Physiological oxidants that are generated by activated phagocytes comprise the main source of oxidative stress during inflammation. Oxidants such as taurine chloramine (TnCl) and hydrogen peroxide (H(2)O(2)) can damage proteins and induce apoptosis, but the role of specific protein oxidation in this process has not been defined. We found that the actin-binding protein cofilin is a key target of oxidation. When oxidation of this single regulatory protein is prevented, oxidant-induced apoptosis is inhibited. Oxidation of cofilin causes it to lose its affinity for actin and to translocate to the mitochondria, where it induces swelling and cytochrome c release by mediating opening of the permeability transition pore (PTP). This occurs independently of Bax activation and requires both oxidation of cofilin Cys residues and dephosphorylation at Ser 3. Knockdown of endogenous cofilin using targeted siRNA inhibits oxidant-induced apoptosis, which is restored by re-expression of wild-type cofilin but not by cofilin containing Cys to Ala mutations. Exposure of cofilin to TnCl results in intramolecular disulphide bonding and oxidation of Met residues to Met sulphoxide, but only Cys oxidation causes cofilin to induce mitochondrial damage.

Keywords

Alanine, amino acid substitution, apoptosis, COS cells, cysteine, enzyme activation, enzyme inhibitors, etoposide, fibroblasts, Humans, hydrogen peroxide, mitochondria, liver, oxidants, plasmids, RNA

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