Proapoptotic BCL-2 family members and mitochondrial dysfunction during ischemia/reperfusion injury, a study employing cardiac HL-1 cells and GFP biosensors

• Published in: Biochimica et biophysica acta Vol. 1757; no. 5; pp. 667 - 678
• Main Authors: Brady, Nathan R., Hamacher-Brady, Anne, Gottlieb, Roberta A.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01-05-2006
• Subjects: Apoptosis; Bax; bcl-2-Associated X Protein - metabolism; BH3 Interacting Domain Death Agonist Protein - genetics; BH3 Interacting Domain Death Agonist Protein - metabolism; Bid; Biosensing Techniques; Caspase 8; Caspases - metabolism; Cell death; Cell Line; Green Fluorescent Proteins - genetics; Green Fluorescent Proteins - metabolism; Humans; Ischemia; MAP Kinase Signaling System - physiology; Membrane Potentials; Microscopy, Fluorescence; Mitochondria; Mitochondria, Heart - pathology; Myocardial Reperfusion Injury - metabolism; Myocardial Reperfusion Injury - pathology; Myocytes, Cardiac - metabolism; Myocytes, Cardiac - pathology; Protein Transport; Recombinant Fusion Proteins - metabolism; Reperfusion; CM-DCF; FP; sI/R; Mitochondria; TMRM; Reperfusion; Ischemia; Cell death; ROS; Bax; MPTP; Bid; KH
• ISSN: 0005-2728; 0006-3002; 1879-2650
• DOI: 10.1016/j.bbabio.2006.04.011

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.