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Nitro-oxidative stress after neuronal ischemia induces protein nitrotyrosination and cell death.

ABSTRACT: Ischemic stroke is an acute vascular event that obstructs blood supply to the brain, producing irreversible damage that affects neurons but also glial and brain vessel cells. Immediately after the stroke, the ischemic tissue produces nitric oxide (NO) to recover blood perfusion but also produces superoxide anion. These compounds interact, producing peroxynitrite, which irreversibly nitrates protein tyrosines. The present study measured NO production in a human neuroblastoma (SH-SY5Y), a murine glial (BV2), a human endothelial cell line (HUVEC), and in primary cultures of human cerebral myocytes (HC-VSMCs) after experimental ischemia in vitro. Neuronal, endothelial, and inducible NO synthase (NOS) expression was also studied up to 24 h after ischemia, showing a different time course depending on the NOS type and the cells studied. Finally, we carried out cell viability experiments on SH-SY5Y cells with H2O2, a prooxidant agent, and with a NO donor to mimic ischemic conditions. We found that both compounds were highly toxic when they interacted, producing peroxynitrite. We obtained similar results when all cells were challenged with peroxynitrite. Our data suggest that peroxynitrite induces cell death and is a very harmful agent in brain ischemia.

SUBMITTER: Tajes M

PROVIDER: S-EPMC3747381 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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Nitro-oxidative stress after neuronal ischemia induces protein nitrotyrosination and cell death.

Tajes Marta M Ill-Raga Gerard G Palomer Ernest E Ramos-Fernández Eva E Guix Francesc X FX Bosch-Morató Mònica M Guivernau Biuse B Jiménez-Conde Jordi J Ois Angel A Pérez-Asensio Fernando F Reyes-Navarro Mario M Caballo Carolina C Galán Ana M AM Alameda Francesc F Escolar Ginés G Opazo Carlos C Planas Anna A Roquer Jaume J Valverde Miguel A MA Muñoz Francisco J FJ

Oxidative medicine and cellular longevity 20130801

Ischemic stroke is an acute vascular event that obstructs blood supply to the brain, producing irreversible damage that affects neurons but also glial and brain vessel cells. Immediately after the stroke, the ischemic tissue produces nitric oxide (NO) to recover blood perfusion but also produces superoxide anion. These compounds interact, producing peroxynitrite, which irreversibly nitrates protein tyrosines. The present study measured NO production in a human neuroblastoma (SH-SY5Y), a murine g ...[more]

PMID: 23983901

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Project description:Oxidative stress has been shown to induce cell death in a wide range of human diseases including cardiac ischemia/reperfusion injury, drug induced cardiotoxicity, and heart failure. However, the mechanism of cell death induced by oxidative stress remains incompletely understood. Here we provide new evidence that oxidative stress primarily induces ferroptosis, but not apoptosis, necroptosis, or mitochondria-mediated necrosis, in cardiomyocytes. Intriguingly, oxidative stress induced by organic oxidants such as tert-butyl hydroperoxide (tBHP) and cumene hydroperoxide (CHP), but not hydrogen peroxide (H2O2), promoted glutathione depletion and glutathione peroxidase 4 (GPX4) degradation in cardiomyocytes, leading to increased lipid peroxidation. Moreover, elevated oxidative stress is also linked to labile iron overload through downregulation of the transcription suppressor BTB and CNC homology 1 (Bach1), upregulation of heme oxygenase 1 (HO-1) expression, and enhanced iron release via heme degradation. Strikingly, oxidative stress also promoted HO-1 translocation to mitochondria, leading to mitochondrial iron overload and lipid reactive oxygen species (ROS) accumulation. Targeted inhibition of mitochondrial iron overload or ROS accumulation, by overexpressing mitochondrial ferritin (FTMT) or mitochondrial catalase (mCAT), respectively, markedly inhibited oxidative stress-induced ferroptosis. The levels of mitochondrial iron and lipid peroxides were also markedly increased in cardiomyocytes subjected to simulated ischemia and reperfusion (sI/R) or the chemotherapeutic agent doxorubicin (DOX). Overexpressing FTMT or mCAT effectively prevented cardiomyocyte death induced by sI/R or DOX. Taken together, oxidative stress induced by organic oxidants but not H2O2 primarily triggers ferroptotic cell death in cardiomyocyte through GPX4 and Bach1/HO-1 dependent mechanisms. Our results also reveal mitochondrial iron overload via HO-1 mitochondrial translocation as a key mechanism as well as a potential molecular target for oxidative stress-induced ferroptosis in cardiomyocytes.

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.

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Nitro-oxidative stress after neuronal ischemia induces protein nitrotyrosination and cell death.

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Nitro-oxidative stress after neuronal ischemia induces protein nitrotyrosination and cell death.

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