Release of cytochrome c into the extracellular space contributes to neuronal apoptosis induced by staurosporine.
The mitochondrial protein cytochrome c has been identified as one of the key signalling molecules of apoptosis. In the present study, we used primary neuronal cultures to investigate whether cytochrome c was released from the mitochondria into the cytosol and subsequently into the culture medium during staurosporine-induced apoptosis and whether extracellular cytochrome c modulates the degree of damage caused by staurosporine. We found the cytochrome c content in the mitochondria decreased 24 h after and increased in the cytosol 8 h after staurosporine was added to the culture medium. The cytochrome c content of the culture medium increased from 8 h up to 24 h after starting the staurosporine treatment. In parallel with the release of cytochrome c into the culture medium, membrane leakage occurred as determined by the release of LDH. Addition of cytochrome c accelerated, whereas the addition of anti-cytochrome c antibodies reduced staurosporine-induced neuronal death suggesting a pro-apoptotic role of cytochrome c released into the culture medium. Under control conditions, extracellularly added cytochrome c (25 ng/ml), which was in the range of the amount of cytochrome c released from staurosporine-treated neurons into the culture medium, increased the percentage of apoptotic neurons to 30% compared with 18% in vehicle-treated controls. Our results suggest that the release of cytochrome c into the extracellular space contributes to neuronal apoptosis induced by staurosporine.
Ahlemeyer
Barbara
B
Institut für Pharmakologie und Toxikologie, Fachbereich Pharmazie der Philipps-Universität Marburg, Ketzerbach 63, D-35032, Marburg, Germany. ahlemeye@mailer.uni-marburg.de
Klumpp
Susanne
S
Krieglstein
Josef
J
D000818:Animals; D000831:Animals, Newborn; D000906:Antibodies / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002463:Cell Membrane Permeability / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D002490:Central Nervous System / Q000166:cytology / Q000196:embryology* / Q000378:metabolism; D002642:Chick Embryo; D003574:Cytochrome c Group / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000494:pharmacology; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism*; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D019636:Neurodegenerative Diseases / Q000378:metabolism / Q000503:physiopathology; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D011916:Rats, Inbred F344; D019311:Staurosporine / Q000494:pharmacology
D000906:Antibodies; D003574:Cytochrome c Group; D004791:Enzyme Inhibitors; D007770:L-Lactate Dehydrogenase; D019311:Staurosporine