Mitochondrial permeability transition relevance for apoptotic triggering in the post-ischemic heart.
Dysfunction of mitochondrial calcium homeostasis transforms this cation from a key regulator of mitochondrial function, into a death effector during post-ischemic reperfusion. High intramitochondrial calcium and prevailing cellular conditions favor the opening of the mitochondrial permeability transition pore (mPTP), that induces mitochondrial swelling and provides a mechanism for cytochrome c release, a hallmark signal protein of the mitochondrial apoptosis pathway; indeed, a second mechanism induced by pro-apoptotic BAX protein, could account for cytochrome c leak in the post-ischemic heart. The present study was undertaken to determine which one of these mechanisms triggers the mitochondrial apoptosis pathway in the reperfused heart. To accomplish this goal we prevented the opening of the mPTP in such hearts, by diminishing calcium overload with Ru360, a specific mitochondrial calcium uniporter inhibitor. We found that mPTP opening in reperfused hearts increased along with reperfusion time and concurs with cytochrome c release from mitochondria. Maximal cytochrome c release correlated with mitochondrial dysfunction and complete NAD+ deletion. Fully inserted BAX was detected early after reperfusion and remained unchanged during the evaluated reperfusion times. Remarkably, heart perfusion with Ru360, inhibited mPTP opening and BAX docking into the mitochondrial membranes, suggesting a mPTP upstream role on BAX migration/insertion.
Correa
Francisco
F
Departamento de Bioquímica, Instituto Nacional de Cardiología Ignacio Chávez, Juan Badiano No. 1, Colonia Sección XVI, México 14080, D.F., Mexico.
Soto
Virgilia
V
Zazueta
Cecilia
C
D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism / Q000493:pharmacokinetics; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D016572:Cyclosporine / Q000494:pharmacology; D045304:Cytochromes c / Q000378:metabolism; D003576:Electron Transport Complex IV / Q000378:metabolism; D006321:Heart / Q000503:physiopathology*; D020287:In Situ Nick-End Labeling; D066298:In Vitro Techniques; D008297:Male; D008929:Mitochondria, Heart / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D008933:Mitochondrial Swelling / Q000187:drug effects / Q000502:physiology*; D015428:Myocardial Reperfusion Injury / Q000503:physiopathology; D009206:Myocardium / Q000378:metabolism; D009243:NAD / Q000378:metabolism; D010539:Permeability / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D017975:Ruthenium Compounds / Q000494:pharmacology; D013997:Time Factors; D014475:Uncoupling Agents / Q000494:pharmacology; D051028:bcl-2-Associated X Protein / Q000378:metabolism
C494828:Bax protein, rat; C112020:Ru 360; D017975:Ruthenium Compounds; D014475:Uncoupling Agents; D051028:bcl-2-Associated X Protein; D009243:NAD; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D016572:Cyclosporine; D045304:Cytochromes c; D003576:Electron Transport Complex IV; D002118:Calcium