Mitochondrial nitroalkene formation and mild uncoupling in ischaemic preconditioning: implications for cardioprotection

Department of Anesthesiology, Box 604, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY 14642, USA.
Cardiovascular Research (Impact Factor: 5.94). 01/2009; 82(2):333-40. DOI: 10.1093/cvr/cvn323
Source: PubMed


Both mitochondria and nitric oxide (NO*) contribute to cardioprotection by ischaemic preconditioning (IPC). IPC causes mild uncoupling of mitochondria via uncoupling proteins (UCPs) and the adenine nucleotide translocase (ANT), and mild uncoupling per se is cardioprotective. Although electrophilic lipids are known to activate mitochondrial uncoupling, the role of such species in IPC-induced uncoupling and cardioprotection is unclear. We hypothesized that endogenous formation of NO*-derived electrophilic lipids (nitroalkenes such as nitro-linoleate, LNO2) during IPC may stimulate mitochondrial uncoupling via post-translational modification of UCPs and ANT, thus affording cardioprotection.
Hearts from male Sprague-Dawley rats were Langendorff-perfused and subjected to IPC. Nitroalkene formation was measured by HPLC-ESI-MS/MS. The effects of exogenous LNO2 and biotin-tagged LNO2 on isolated heart mitochondria and cardiomyocytes were also investigated.
Nitroalkenes including LNO2 were endogenously generated in mitochondria of IPC hearts. Synthetic LNO2 (<1 microM) activated mild uncoupling, an effect blocked by UCP and ANT inhibitors. LNO2 (<1 microM) also protected cardiomyocytes against simulated ischaemia-reperfusion injury. Biotinylated LNO2 covalently modified ANT thiols and possibly UCP-2. No effects of LNO2 were attributable to NO* release, cGMP signalling, mitochondrial KATP channels, or protective kinase signalling.
Components of a novel signalling pathway are inferred, wherein nitroalkenes formed by IPC-stimulated nitration reactions may induce mild mitochondrial uncoupling via post-translational modification of ANT and UCP-2, subsequently conferring resistance to ischaemia-reperfusion injury.

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Available from: Bruce A Freeman, Oct 02, 2015
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    • "This is explained by the facile and reversible Michael addition of NO2-FA with susceptible thiols of specific protein targets, thus requiring only low concentrations and rates of generation of electrophilic lipids to result in the accumulation of target protein adduction and instigation of downstream signaling responses [16], [54]. Consequently, electrophilic lipids which are present in plants, generated by digestion of plant lipids, produced by oxidative inflammatory reactions or administered as pure synthetic homologs [24], [26], [47], [56], can regulate metabolism and the resolution of inflammatory processes. In this regard, olives and EVOO serve as both a direct source of and precursors for NO2-FA generation. "
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    ABSTRACT: Extra virgin olive oil (EVOO) and olives, key sources of unsaturated fatty acids in the Mediterranean diet, provide health benefits to humans. Nitric oxide (•NO) and nitrite (NO2 (-))-dependent reactions of unsaturated fatty acids yield electrophilic nitroalkene derivatives (NO2-FA) that manifest salutary pleiotropic cell signaling responses in mammals. Herein, the endogenous presence of NO2-FA in both EVOO and fresh olives was demonstrated by mass spectrometry. The electrophilic nature of these species was affirmed by the detection of significant levels of protein cysteine adducts of nitro-oleic acid (NO2-OA-cysteine) in fresh olives, especially in the peel. Further nitration of EVOO by NO2 (-) under acidic gastric digestive conditions revealed that human consumption of olive lipids will produce additional nitro-conjugated linoleic acid (NO2-cLA) and nitro-oleic acid (NO2-OA). The presence of free and protein-adducted NO2-FA in both mammalian and plant lipids further affirm a role for these species as signaling mediators. Since NO2-FA instigate adaptive anti-inflammatory gene expression and metabolic responses, these redox-derived metabolites may contribute to the cardiovascular benefits associated with the Mediterranean diet.
    PLoS ONE 01/2014; 9(1):e84884. DOI:10.1371/journal.pone.0084884 · 3.23 Impact Factor
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    • "The formation of cholesteryl nitrolinoleate (NO2-CL) by activated macrophages is prevented by nitric oxide synthase (NOS) inhibitors, supporting the contribution of •NO-derived species toward CL nitration. More recently, it has been demonstrated that NO2-FA is both present and formed in mitochondria from cardiac ischemia/reperfusion (13) or ischemic preconditioned (14) hearts. "
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    ABSTRACT: Nitro-fatty acids are formed and detected in human plasma, cell membranes, and tissue, modulating metabolic as well as inflammatory signaling pathways. Here we discuss the mechanisms of nitro-fatty acid formation as well as their key chemical and biochemical properties. The electrophilic properties of nitro-fatty acids to activate anti-inflammatory signaling pathways are discussed in detail. A critical issue is the influence of nitroarachidonic acid on prostaglandin endoperoxide H synthases, redirecting arachidonic acid metabolism and signaling. We also analyze in vivo data supporting nitro-fatty acids as promising pharmacological tools to prevent inflammatory diseases.
    Brazilian journal of medical and biological research = Revista brasileira de pesquisas medicas e biologicas / Sociedade Brasileira de Biofisica ... [et al.] 09/2013; 46(9):735-8. DOI:10.1590/1414-431X20133202 · 1.01 Impact Factor
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    • "Complex IV (cytochrome c oxidase) has been shown to be inhibited by NO∙, which is released during I/R [63, 70]. Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) was also inhibited by endogenously derived nitrolipids generated during IPC [71, 72]. This causes the accumulation of fructose-1,6-bisphosphate (F-1,6-BP) which has been observed to improve glycolytic flux and functional recovery in post-ischemic myocardium [73]. "
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    ABSTRACT: Cardiac function is compromised by oxidative stress which occurs upon exposing the heart to ischemia reperfusion (I/R) for a prolonged period. The reactive oxygen species (ROS) that are generated during I/R incur extensive damage to the myocardium and result in subcellular organelle remodeling. The cardiac nucleus, glycocalyx, myofilaments, sarcoplasmic reticulum, sarcolemma, and mitochondria are affected by ROS during I/R injury. On the other hand, brief periods of ischemia followed by reperfusion, or ischemic preconditioning (IPC), have been shown to be cardioprotective against oxidative stress by attenuating the cellular damage and alterations of subcellular organelles caused by subsequent I/R injury. Endogenous defense mechanisms, such as antioxidant enzymes and heat shock proteins, are activated by IPC and thus prevent damage caused by oxidative stress. Although these cardioprotective effects of IPC against I/R injury are considered to be a consequence of changes in the redox state of cardiomyocytes, IPC is considered to promote the production of NO which may protect subcellular organelles from the deleterious actions of oxidative stress. The article is intended to focus on the I/R-induced oxidative damage to subcellular organelles and to highlight the cardioprotective effects of IPC. In addition, the actions of various endogenous cardioprotective interventions are discussed to illustrate that changes in the redox state due to IPC are cardioprotective against I/R injury to the heart.
    Current Cardiology Reviews 11/2010; 6(4):255-64. DOI:10.2174/157340310793566118
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