Dataset Information

Osteopontin-stimulated apoptosis in cardiac myocytes involves oxidative stress and mitochondrial death pathway: role of a pro-apoptotic protein BIK.

ABSTRACT: Increased osteopontin (OPN) expression in the heart, specifically in myocytes, associates with increased myocyte apoptosis and myocardial dysfunction. Recently, we provided evidence that OPN interacts with CD44 receptor, and induces myocyte apoptosis via the involvement of endoplasmic reticulum stress and mitochondrial death pathways. Here we tested the hypothesis that OPN induces oxidative stress in myocytes and the heart via the involvement of mitochondria and NADPH oxidase-4 (NOX-4). Treatment of adult rat ventricular myocytes (ARVMs) with OPN (20 nM) increased oxidative stress as analyzed by protein carbonylation, and intracellular reactive oxygen species (ROS) levels as analyzed by ROS detection kit and dichlorohydrofluorescein diacetate staining. Pretreatment with NAC (antioxidant), apocynin (NOX inhibitor), MnTBAP (superoxide dismutase mimetic), and mitochondrial KATP channel blockers (glibenclamide and 5-hydroxydecanoate) decreased OPN-stimulated ROS production, cytosolic cytochrome c levels, and apoptosis. OPN increased NOX-4 expression, while decreasing SOD-2 expression. OPN decreased mitochondrial membrane potential as measured by JC-1 staining, and induced mitochondrial abnormalities including swelling and reorganization of cristae as observed using transmission electron microscopy. OPN increased expression of BIK, a pro-apoptotic protein involved in reorganization of mitochondrial cristae. Expression of dominant-negative BIK decreased OPN-stimulated apoptosis. In vivo, OPN expression in cardiac myocyte-specific manner associated with increased protein carbonylation, and expression of NOX-4 and BIK. Thus, OPN induces oxidative stress via the involvement of mitochondria and NOX-4. It may affect mitochondrial morphology and integrity, at least in part, via the involvement of BIK.

SUBMITTER: Dalal S

PROVIDER: S-EPMC5559874 | biostudies-other | 2016 Jul

REPOSITORIES: biostudies-other

ACCESS DATA

Similar Datasets

Project description:We previously demonstrated that protein kinase C? (PKC?; PKC delta) is an oxidative stress-sensitive kinase that plays a causal role in apoptotic cell death in neuronal cells. Although PKC? activation has been extensively studied, relatively little is known about the molecular mechanisms controlling PKC? expression. To characterize the regulation of PKC? expression, we cloned an ?2-kbp 5'-promoter segment of the mouse Prkcd gene. Deletion analysis indicated that the noncoding exon 1 region contained multiple Sp sites, including four GC boxes and one CACCC box, which directed the highest levels of transcription in neuronal cells. In addition, an upstream regulatory region containing adjacent repressive and anti-repressive elements with opposing regulatory activities was identified within the region -712 to -560. Detailed mutagenesis studies revealed that each Sp site made a positive contribution to PKC? promoter expression. Overexpression of Sp family proteins markedly stimulated PKC? promoter activity without any synergistic transactivating effect. Furthermore, experiments in Sp-deficient SL2 cells indicated long isoform Sp3 as the essential activator of PKC? transcription. Importantly, both PKC? promoter activity and endogenous PKC? expression in NIE115 cells and primary striatal cultures were inhibited by mithramycin A. The results from chromatin immunoprecipitation and gel shift assays further confirmed the functional binding of Sp proteins to the PKC? promoter. Additionally, we demonstrated that overexpression of p300 or CREB-binding protein increases the PKC? promoter activity. This stimulatory effect requires intact Sp-binding sites and is independent of p300 histone acetyltransferase activity. Finally, modulation of Sp transcriptional activity or protein level profoundly altered the cell death induced by oxidative insult, demonstrating the functional significance of Sp-dependent PKC? gene expression. Collectively, our findings may have implications for development of new translational strategies against oxidative damage.

Dataset Information

Osteopontin-stimulated apoptosis in cardiac myocytes involves oxidative stress and mitochondrial death pathway: role of a pro-apoptotic protein BIK.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets