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Osteopontin‐Stimulated Apoptosis in Cardiac Myocytes Involves Reactive Oxygen Species and Mitochondrial Pathway
Author(s) -
Dalal Suman,
Singh Mahipal,
Singh Krishna
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.975.4
Subject(s) - mitochondrial ros , reactive oxygen species , apocynin , nadph oxidase , mitochondrion , apoptosis , oxidative stress , myocyte , chemistry , microbiology and biotechnology , osteopontin , cytochrome c , biology , biochemistry , endocrinology
Increased osteopontin (OPN) expression associates with increased myocyte apoptosis and myocardial dysfunction. Recently, we have shown that OPN stimulates cardiac myocyte apoptosis via the involvement of endoplasmic reticulum stress and mitochondrial death pathways. The objective of this study was to evaluate the production and source of reactive oxygen species (ROS), and their role in OPN‐stimulated myocyte apoptosis. Treatment of adult rat ventricular myocytes (ARVMs) with OPN (20 nM) induced protein oxidation as analyzed by protein carbonylation assay. Direct monitoring of ARVMs using total ROS detection kit and DCFDA (2',7'‐dichlorofluorescin diacetate; a fluorogenic dye) staining showed increased number of ROS‐positive cells in response to OPN. OPN induced mitochondrial depolarization, and decreased the expression of mitochondrial antioxidant enzyme, manganese superoxide dismutase‐2 (SOD‐2). Transmission electron microscopy revealed that OPN induces mitochondrial abnormalities including swelling and reorganization of cristae. OPN‐mediated increase in the levels of cytosolic cytochrome c and apoptosis were significantly inhibited by N‐acetyl‐cysteine (antioxidant), apocynin (NADPH oxidase inhibitor), MnTBAP [Mn(III)tetrakis (4‐benzoic acid) porphyrin; SOD mimic] and glibenclamide (mitochondrial K ATP channel blocker). These data suggest that OPN induces ROS production, and affects mitochondrial morphology and integrity. Mitochondria may serve as a source of ROS production through the opening of mK ATP channels. Supported by Department of Veterans Affairs (BX002332) and NIH