Cytochrome c is released in a single step during apoptosis.
Release of cytochrome c from mitochondria is a central event in apoptotic signaling. In this study, we utilized a cytochrome c fusion that binds fluorescent biarsenical ligands (cytochrome c-4CYS (cyt. c-4CYS)) as well as cytochrome c-green fluorescent protein (cyt. c-GFP) to measure its release from mitochondria in different cell types during apoptosis. In single cells, the kinetics of cyt. c-4CYS release was indistinguishable from that of cyt. c-GFP in apoptotic cells expressing both molecules. Lowering the temperature by 7 degrees C did not affect this corelease, but further separated cytochrome c release from the subsequent decrease in mitochondrial membrane potential (DeltaPsi(m)). Cyt. c-GFP rescued respiration in cells lacking endogenous cytochrome c, and the duration of cytochrome c release was approximately 5 min in a variety of cell types induced to die by various forms of cellular stress. In addition, we could observe no evidence of caspase-dependent amplification of cytochrome c release or changes in DeltaPsi(m) preceding the release of cyt. c-GFP. We conclude that there is a general mechanism responsible for cytochrome c release that proceeds in a single step that is independent of changes in DeltaPsi(m).
Goldstein
J C
JC
La Jolla Institute for Allergy and Immunology, 10355 Science Center Dr., San Diego, CA 92121, USA.
Muñoz-Pinedo
C
C
Ricci
J-E
JE
Adams
S R
SR
Kelekar
A
A
Schuler
M
M
Tsien
R Y
RY
Green
D R
DR
D017209:Apoptosis / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D015415:Biomarkers; D045304:Cytochromes c / Q000378:metabolism*; D003609:Dactinomycin / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D019169:Jurkat Cells; D007700:Kinetics; D008024:Ligands; D008564:Membrane Potentials / Q000187:drug effects; D018715:Microscopy, Video; D008928:Mitochondria / Q000187:drug effects / Q000502:physiology; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D019311:Staurosporine / Q000494:pharmacology; D013696:Temperature; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D014466:Ultraviolet Rays
D015415:Biomarkers; D004791:Enzyme Inhibitors; D008024:Ligands; D011500:Protein Synthesis Inhibitors; D014409:Tumor Necrosis Factor-alpha; D049452:Green Fluorescent Proteins; D003609:Dactinomycin; D045304:Cytochromes c; D019311:Staurosporine