Apoptosis-inducing factor plays a critical role in caspase-independent, pyknotic cell death in hydrogen peroxide-exposed cells.
It has been proposed that continuously generated hydrogen peroxide (H(2)O(2)) inhibits typical apoptosis and instead initiates an alternate, apoptosis-inducing factor (AIF)-dependent process. Aside from the role of AIF, however, the detailed morphological characterization of H(2)O(2)-induced cell death is not complete. This study examined the cellular mechanism(s) by which the continuous presence of H(2)O(2) induces cell death. We also further analyzed the precise role of AIF by inhibiting its expression with siRNA. Exposure of cells to H(2)O(2) generated by glucose oxidase caused mitochondrion-mediated, caspase-independent cell death. In addition, H(2)O(2) exposure resulted in cell shrinkage and chromatin condensation without nuclear fragmentation, indicating that H(2)O(2) stimulates a pyknotic cell death. Further analysis of AIF-transfected cells clearly demonstrated that nuclear translocation of AIF is the most important event required for nuclear condensation, phosphatidyl serine translocation, and ultimately cell death in H(2)O(2)-exposed cells. Furthermore, ATP was rapidly and severely depleted in cells exposed to H(2)O(2) generated by glucose oxidase but not by H(2)O(2) added as a bolus. Suppression of the H(2)O(2)-mediated ATP depletion by 3-aminobenzamide led to a significant increase of nuclear fragmentation in glucose oxidase-exposed cells. Collectively, these findings suggest that an acute energy reduction by H(2)O(2) causes caspase-independent and AIF-dependent cell death.
Graduate Center for Toxicology, University of Kentucky, Lexington, KY 40536-0001, USA.
Young-Ok
YO
Son
Yong-Suk
YS
Jang
Jung-Sun
JS
Heo
Wan-Tae
WT
Chung
Ki-Choon
KC
Choi
Jeong-Chae
JC
Lee
D000255:Adenosine Triphosphate / Q000378:metabolism; D051033:Apoptosis Inducing Factor / Q000378:metabolism*; D020169:Caspases / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D002843:Chromatin / Q000378:metabolism; D053938:DNA Fragmentation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005949:Glucose Oxidase / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D010718:Phosphatidylserines / Q000378:metabolism; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D021381:Protein Transport / Q000187:drug effects; D034741:RNA, Small Interfering / Q000378:metabolism; D014162:Transfection
D051033:Apoptosis Inducing Factor; D002843:Chromatin; D004791:Enzyme Inhibitors; D010718:Phosphatidylserines; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D034741:RNA, Small Interfering; D000255:Adenosine Triphosphate; D006861:Hydrogen Peroxide; D005949:Glucose Oxidase; D020169:Caspases