title: Retroactive pathway involving mitochondria in electroloaded cytochrome c-induced apoptosis. Protective properties of Bcl-2 and Bcl-XL.
abstract: Cytochrome c release is thought to play an important role in the initiation of apoptosis. The nature of the control exerted by Bcl-2 and Bcl-XL on such a pathway is not precisely known. We addressed this issue by square-wave pulse electroloading of exogenous cytochrome c into Jurkat cells. Three hours after cytochrome c loading into the cells, characteristic phenotypes of apoptosis were observed. However, a significant drop in the mitochondrial membrane potential (Deltapsim) was also observed, while cytochrome c was generally considered to act downstream from the mitochondria. Related to the Deltapsim drop, there was a release of proapoptotic proteins such as AIF and Smac from the mitochondria. This release, as well as NAD(P)H and cardiolipids oxidation, are linked to previous caspase activation. Cytochrome c-linked caspase activation also led to potassium efflux out of the cell. Overexpression of Bcl-2 and Bcl-XL or N-acetyl-DEVD-aldehyde treatment not only prevented the mitochondrial membrane potential decrease, but also protected cells from the apoptosis directly induced by cytochrome c electroloading. Bcl-2 and Bcl-XL protection is based on the inhibition of the caspase-dependent retroactive pathway affecting the mitochondrial compartment.
mesh_terms: D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D051033:Apoptosis Inducing Factor; D051017:Apoptosis Regulatory Proteins; D002352:Carrier Proteins / Q000378:metabolism; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D003574:Cytochrome c Group / Q000378:metabolism* / Q000494:pharmacology; D018274:Electroporation / Q000379:methods; D005420:Flavoproteins / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000502:physiology; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D019169:Jurkat Cells; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008565:Membrane Proteins / Q000378:metabolism; D008928:Mitochondria / Q000187:drug effects / Q000201:enzymology*; D024101:Mitochondrial Proteins / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D051020:bcl-X Protein
chemical_list: C494829:AIFM1 protein, human; D051033:Apoptosis Inducing Factor; D051017:Apoptosis Regulatory Proteins; C494811:BCL2L1 protein, human; D002352:Carrier Proteins; D003574:Cytochrome c Group; C412403:DIABLO protein, human; D005420:Flavoproteins; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051020:bcl-X Protein; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases