Proapoptotic BCL-2 family members and mitochondrial dysfunction during ischemia/reperfusion injury, a study employing cardiac HL-1 cells and GFP biosensors.
The objective of this study was to evaluate mitochondrial alterations in a cell-based model of myocardial ischemia/reperfusion (I/R) injury. Using GFP-biosensors and fluorescence deconvolution microscopy, we investigated mitochondrial morphology in relation to Bax and Bid activation in the HL-1 cardiac cell line. Mitochondria underwent extensive fragmentation during ischemia. Bax translocation from cytosol to mitochondria was initiated during ischemia and proceeded during reperfusion. However, Bax translocation was not sufficient to induce cell death or mitochondrial dysfunction. Bid processing was caspase-8 dependent, and Bid translocation to mitochondria occurred after Bax translocation and clustering, and minutes before cell death. Clustering of Bax into distinct regions on mitochondria could be prevented by CsA, an inhibitor of the mitochondrial permeability transition pore, and also by SB203580, an inhibitor of p38 MAPK. Surprisingly, mitochondrial fragmentation which occurred during ischemia and before Bax translocation could be reversed by the addition of the p38 inhibitor SB203580 at reperfusion. Taken together, these results implicate p38 MAPK in the mitochondrial remodeling response to I/R that facilitates Bax recruitment to mitochondria.
Brady
Nathan R
NR
Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA.
Hamacher-Brady
Anne
A
Gottlieb
Roberta A
RA
D017209:Apoptosis; D051023:BH3 Interacting Domain Death Agonist Protein / Q000235:genetics / Q000378:metabolism*; D015374:Biosensing Techniques; D053181:Caspase 8; D020169:Caspases / Q000378:metabolism; D002460:Cell Line; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D020935:MAP Kinase Signaling System / Q000502:physiology; D008564:Membrane Potentials; D008856:Microscopy, Fluorescence; D008929:Mitochondria, Heart / Q000473:pathology*; D015428:Myocardial Reperfusion Injury / Q000378:metabolism / Q000473:pathology*; D032383:Myocytes, Cardiac / Q000378:metabolism / Q000473:pathology*; D021381:Protein Transport; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D051028:bcl-2-Associated X Protein / Q000378:metabolism*
D051023:BH3 Interacting Domain Death Agonist Protein; D011993:Recombinant Fusion Proteins; D051028:bcl-2-Associated X Protein; D049452:Green Fluorescent Proteins; C505530:CASP8 protein, human; D053181:Caspase 8; D020169:Caspases