Mitochondrial dysfunction in cardiac ischemia–reperfusion injury: ROS from complex I, without inhibition

Department of Anesthesiology, University of Rochester, Rochester, New York, United States
Biochimica et Biophysica Acta (Impact Factor: 4.66). 03/2006; 1762(2):223-31. DOI: 10.1016/j.bbadis.2005.10.001
Source: PubMed


A key pathologic event in cardiac ischemia reperfusion (I-R) injury is mitochondrial energetic dysfunction, and several studies have attributed this to complex I (CxI) inhibition. In isolated perfused rat hearts, following I-R, we found that CxI-linked respiration was inhibited, but isolated CxI enzymatic activity was not. Using the mitochondrial thiol probe iodobutyl-triphenylphosphonium in conjunction with proteomic tools, thiol modifications were identified in several subunits of the matrix-facing 1alpha sub-complex of CxI. These thiol modifications were accompanied by enhanced ROS generation from CxI, but not complex III. Implications for the pathology of cardiac I-R injury are discussed.

Download full-text


Available from: Lindsay Burwell, Mar 03, 2015
  • Source
    • "More recently, we showed that IBTP inhibited overall metabolism in breast cancer cells after a short (4h) exposure, and also prevented cell migration and adhesion [27]. Due to the soft electrophilic nature of IBTP, this compound forms a covalent adduct with specific cysteinyl thiol groups of proteins, many of which play a central role in cell metabolism [24] [25] [28] [29]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Many cancer cells follow an aberrant metabolic program to maintain energy for rapid cell proliferation. Metabolic reprogramming often involves the upregulation of glutaminolysis to generate reducing equivalents for the electron transport chain and amino acids for protein synthesis. Critical enzymes involved in metabolism possess a reactive thiolate group, which can be modified by certain oxidants. In the current study, we show that modification of mitochondrial protein thiols by a model compound, iodobutyl triphenylphosphonium (IBTP), decreased mitochondrial metabolism and ATP in MDA-MB 231 (MB231) breast adenocarcinoma cells up to 6 days after an initial 24h treatment. Mitochondrial thiol modification also depressed oxygen consumption rates (OCR) in a dose-dependent manner to a greater extent than a non-thiol modifying analog, suggesting that thiol reactivity is an important factor in the inhibition of cancer cell metabolism. In non-tumorigenic MCF10A cells, IBTP also decreased OCR; however the extracellular acidification rate was significantly increased at all but the highest concentration (10µM) of IBTP indicating that thiol modification can have significantly different effects on bioenergetics in tumorigenic versus non-tumorigenic cells. ATP and other adenonucleotide levels were also decreased by thiol modification up to 6 days post-treatment, indicating a decreased overall energetic state in MB231 cells. Cellular proliferation of MB231 cells was also inhibited up to 6 days post-treatment with little change to cell viability. Targeted metabolomic analyses revealed that thiol modification caused depletion of both Krebs cycle and glutaminolysis intermediates. Further experiments revealed that the activity of the Krebs cycle enzyme, aconitase, was attenuated in response to thiol modification. Additionally, the inhibition of glutaminolysis corresponded to decreased glutaminase C (GAC) protein levels, although other protein levels were unaffected. This study demonstrates for the first time that mitochondrial thiol modification inhibits metabolism via inhibition of both aconitase and GAC in a breast cancer cell model.
    Full-text · Article · Jan 2016
  • Source
    • "The energetic requirements of cardiac myocytes are mainly met by mitochondria. This organelle also plays important roles in maintaining intracellular Ca 2+ homeostasis and in regulating cell death [14]. With ischemia, the loss of O 2 and consequent decrease in ATP levels disrupts cardiac myocyte ionic homeostasis resulting in depolarization and cytoplasmic Ca 2+ accumulation [15]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Background: Targeting the mitochondria during ischemia/reperfusion (IR) can confer cardioprotection leading to improved clinical outcomes. The cardioprotective potential of (-)-epicatechin (EPI) during IR via modulation of mitochondrial function was evaluated. Methods and results: Ischemia was induced in rats via a 45 min occlusion of the left anterior descending coronary artery followed by 1 h, 48 h, or 3 week reperfusion. EPI (10 mg/kg) was administered IV 15 min prior to reperfusion for the single dose group and again 12 h later for the double dose group. Controls received water. Experiments also utilized cultured neonatal rat ventricular myocytes (NRVM) and myoblasts. A single dose of EPI reduced infarct size by 27% at 48 h and 28% at 3 week. Double dose treatment further decreased infarct size by 80% at 48 h, and 52% by 3 weeks. The protective effect of EPI on mitochondrial function was evident after 1h of reperfusion when mitochondria demonstrated less respiratory inhibition, lower mitochondrial Ca2+ load, and a preserved pool of NADH that correlated with higher tissue ATP levels. Mechanistic studies in NRVM revealed that EPI acutely stimulated maximal rates of respiration, an effect that was blocked by inhibitors of the mitochondrial pyruvate carrier, nitric oxide synthase, or soluble guanylyl cyclase. In myoblasts, knockdown of components of the mitochondrial pyruvate carrier blocked EPI-induced respiratory stimulation. Conclusions: IV EPI confers cardioprotection via preservation of mitochondrial function potentially through enhanced substrate provision. These provocative results document a novel mechanism of a natural product with potential clinical utility.
    Full-text · Article · May 2014 · International Journal of Cardiology
  • Source
    • "These data suggest that mitochondrial oxidative stress plays a critical role in AngII-induced gap junction remodeling and arrhythmia. As mitochondrial ROS are increased in cardiac diseases such as cardiac hypertrophy [48], myocardial ischemia [50] [210], and heart failure [51] [52], conditions that are known to be associated with RAS activation, ventricular Cx43 downregulation, and increased risk of arrhythmias, it would be of great interest to test if treatment with mitochondria-targeted antioxidant can normalize Cx43 expression and prevent life-threatening arrhythmias in these pathological conditions. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Mitochondria are essential to providing ATP thereby satisfying the energy demand of the incessant electrical activity and contractile action of cardiac muscle. Emerging evidence indicates that mitochondrial dysfunction can adversely impact cardiac electrical functioning by impairing the intracellular ion homeostasis and membrane excitability through reduced ATP production and excessive reactive oxidative species (ROS) generation, resulting in increased propensity to cardiac arrhythmias. In this review, the molecular mechanisms linking mitochondrial dysfunction to cardiac arrhythmias are discussed with an emphasis on the impact of increased mitochondrial ROS on the cardiac ion channels and transporters that are critical to maintaining normal electromechanical functioning of the cardiomyocytes. The potential of using mitochondria-targeted antioxidants as a novel anti-arrhythmia therapy is highlighted.
    Full-text · Article · Apr 2014 · Free Radical Biology and Medicine
Show more