Oxidant-induced apoptosis is mediated by oxidation of the actin-regulatory protein cofilin.
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.
Klamt
Fábio
F
Laboratory of Biochemistry, Division of Therapeutic Proteins, Center for Drug Evaluation and Research, Food and Drug Administration, Bethesda, MD 20892, USA.
Zdanov
Stéphanie
S
Levine
Rodney L
RL
Pariser
Ashley
A
Zhang
Yaqin
Y
Zhang
Baolin
B
Yu
Li-Rong
LR
Veenstra
Timothy D
TD
Shacter
Emily
E
D000409:Alanine / Q000378:metabolism; D019943:Amino Acid Substitution; D000818:Animals; D017209:Apoptosis; D019556:COS Cells; D002522:Chlorocebus aethiops; D051338:Cofilin 1 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D003545:Cysteine / Q000378:metabolism; D003574:Cytochrome c Group / Q000378:metabolism; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000378:metabolism; D005047:Etoposide / Q000378:metabolism; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D008930:Mitochondria, Liver / Q000378:metabolism; D016877:Oxidants / Q000378:metabolism*; D010084:Oxidation-Reduction; D010957:Plasmids / Q000235:genetics; D034741:RNA, Small Interfering / Q000378:metabolism; D051381:Rats; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D013347:Subcellular Fractions / Q000378:metabolism; D013654:Taurine / Q000031:analogs & derivatives / Q000378:metabolism; D013997:Time Factors; D014162:Transfection; D050998:bcl-2 Homologous Antagonist-Killer Protein / Q000378:metabolism; D051028:bcl-2-Associated X Protein / Q000378:metabolism
D051338:Cofilin 1; D003574:Cytochrome c Group; D004791:Enzyme Inhibitors; D016877:Oxidants; D034741:RNA, Small Interfering; D011994:Recombinant Proteins; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051028:bcl-2-Associated X Protein; C076615:cytochrome c''; D013654:Taurine; C043410:N-chlorotaurine; D005047:Etoposide; D006861:Hydrogen Peroxide; D003545:Cysteine; D000409:Alanine