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1.
Acta Physiol (Oxf) ; : e14202, 2024 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-39016532

RESUMO

AIM: The transcriptional factor HIF-1α is recognized for its contribution to cardioprotection against acute ischemia/reperfusion injury. Adaptation to chronic hypoxia (CH) is known to stabilize HIF-1α and increase myocardial ischemic tolerance. However, the precise role of HIF-1α in mediating the protective effect remains incompletely understood. METHODS: Male wild-type (WT) mice and mice with partial Hif1a deficiency (hif1a+/-) were exposed to CH for 4 weeks, while their respective controls were kept under normoxic conditions. Subsequently, their isolated perfused hearts were subjected to ischemia/reperfusion to determine infarct size, while RNA-sequencing of isolated cardiomyocytes was performed. Mitochondrial respiration was measured to evaluate mitochondrial function, and western blots were performed to assess mitophagy. RESULTS: We demonstrated enhanced ischemic tolerance in WT mice induced by adaptation to CH compared with their normoxic controls and chronically hypoxic hif1a+/- mice. Through cardiomyocyte bulk mRNA sequencing analysis, we unveiled significant reprogramming of cardiomyocytes induced by CH emphasizing mitochondrial processes. CH reduced mitochondrial content and respiration and altered mitochondrial ultrastructure. Notably, the reduced mitochondrial content correlated with enhanced autophagosome formation exclusively in chronically hypoxic WT mice, supported by an increase in the LC3-II/LC3-I ratio, expression of PINK1, and degradation of SQSTM1/p62. Furthermore, pretreatment with the mitochondrial division inhibitor (mdivi-1) abolished the infarct size-limiting effect of CH in WT mice, highlighting the key role of mitophagy in CH-induced cardioprotection. CONCLUSION: These findings provide new insights into the contribution of HIF-1α to cardiomyocyte survival during acute ischemia/reperfusion injury by activating the selective autophagy pathway.

2.
Redox Biol ; 63: 102755, 2023 07.
Artigo em Inglês | MEDLINE | ID: mdl-37224696

RESUMO

During cardiac ischemia-reperfusion, excess reactive oxygen species can damage mitochondrial, cellular and organ function. Here we show that cysteine oxidation of the mitochondrial protein Opa1 contributes to mitochondrial damage and cell death caused by oxidative stress. Oxy-proteomics of ischemic-reperfused hearts reveal oxidation of the C-terminal C786 of Opa1 and treatment of perfused mouse hearts, adult cardiomyocytes, and fibroblasts with H2O2 leads to the formation of a reduction-sensitive ∼180 KDa Opa1 complex, distinct from the ∼270 KDa one antagonizing cristae remodeling. This Opa1 oxidation process is curtailed by mutation of C786 and of the other 3 Cys residues of its C-terminal domain (Opa1TetraCys). When reintroduced in Opa1-/- cells, Opa1TetraCys is not efficiently processed into short Opa1TetraCys and hence fails to fuse mitochondria. Unexpectedly, Opa1TetraCys restores mitochondrial ultrastructure in Opa1-/- cells and protects them from H2O2-induced mitochondrial depolarization, cristae remodeling, cytochrome c release and cell death. Thus, preventing the Opa1 oxidation occurring during cardiac ischemia-reperfusion reduces mitochondrial damage and cell death induced by oxidative stress independent of mitochondrial fusion.


Assuntos
Doença da Artéria Coronariana , Traumatismo por Reperfusão Miocárdica , Atrofia Óptica Autossômica Dominante , Animais , Camundongos , Morte Celular , Cisteína/metabolismo , Peróxido de Hidrogênio , Traumatismo por Reperfusão Miocárdica/metabolismo , Atrofia Óptica Autossômica Dominante/metabolismo , Estresse Oxidativo
3.
Basic Res Cardiol ; 118(1): 4, 2023 01 20.
Artigo em Inglês | MEDLINE | ID: mdl-36670288

RESUMO

During embryonic development, cardiomyocytes undergo differentiation and maturation, processes that are tightly regulated by tissue-specific signaling cascades. Although redox signaling pathways involved in cardiomyogenesis are established, the exact sources responsible for reactive oxygen species (ROS) formation remain elusive. The present study investigates whether ROS produced by the mitochondrial flavoenzyme monoamine oxidase A (MAO-A) play a role in cardiomyocyte differentiation from human induced pluripotent stem cells (hiPSCs). Wild type (WT) and MAO-A knock out (KO) hiPSCs were generated by CRISPR/Cas9 genome editing and subjected to cardiomyocyte differentiation. Mitochondrial ROS levels were lower in MAO-A KO compared to the WT cells throughout the differentiation process. MAO-A KO hiPSC-derived cardiomyocytes (hiPSC-CMs) displayed sarcomere disarray, reduced α- to ß-myosin heavy chain ratio, GATA4 upregulation and lower macroautophagy levels. Functionally, genetic ablation of MAO-A negatively affected intracellular Ca2+ homeostasis in hiPSC-CMs. Mechanistically, MAO-A generated ROS contributed to the activation of AKT signaling that was considerably attenuated in KO cells. In addition, MAO-A ablation caused a reduction in WNT pathway gene expression consistent with its reported stimulation by ROS. As a result of WNT downregulation, expression of MESP1 and NKX2.5 was significantly decreased in MAO-A KO cells. Finally, MAO-A re-expression during differentiation rescued expression levels of cardiac transcription factors, contractile structure, and intracellular Ca2+ homeostasis. Taken together, these results suggest that MAO-A mediated ROS generation is necessary for the activation of AKT and WNT signaling pathways during cardiac lineage commitment and for the differentiation of fully functional human cardiomyocytes.


Assuntos
Células-Tronco Pluripotentes Induzidas , Miócitos Cardíacos , Humanos , Miócitos Cardíacos/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Monoaminoxidase/genética , Monoaminoxidase/metabolismo , Diferenciação Celular/fisiologia , Via de Sinalização Wnt
4.
J Nutr Biochem ; 101: 108921, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-34864150

RESUMO

The anthocyanin class of flavonoids, including cyanidin-3-glucoside (C3G) present in berries, blood oranges and pigmented cereal crops, are food bioactives with antioxidant and anti-inflammatory action, capable to reduce myocardial ischemia/reperfusion (I/R) injury by unclear mechanism. Assessing the value of sporadic beneficial diet is critical for practical application. We aimed to determine whether and how the cardioptotective effect of dietary intake of anthocyanins persists. Gene expression, histology and resistance to I/R were investigated ex vivo in hearts from mice after a month beyond the cease of the C3G-enriched diet. Cardiac injury, oxidative stress and mitochondrial damage following I/R was effectively reduced in mice fed C3G-enriched diet, even after a month of wash out with standard diet. Cardioprotection was observed also in immune-deficient mice lacking mature B and T cells indicating the anti-inflammatory activity of C3G was not involved. Moreover, the transcription reprogramming induced by the C3G-enriched diets was rescued by the wash out treatment. Instead, we found C3G-enriched diet changed the microbiome and the transplantation of the fecal microbiota transferred the cardioprotection from mice fed C3G-enriched diet to mice fed standard diet. These findings established the effect of C3G dietary intake on gut microbiota determines long lasting cardioprotection.


Assuntos
Antocianinas/administração & dosagem , Cardiotônicos , Dieta , Microbioma Gastrointestinal , Traumatismo por Reperfusão Miocárdica/prevenção & controle , Animais , Ingestão de Alimentos , Transplante de Microbiota Fecal , Linfócitos/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos NOD , Mitocôndrias Cardíacas/metabolismo
5.
Antioxid Redox Signal ; 34(7): 531-550, 2021 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-32524823

RESUMO

Aims: Doxorubicin cardiomyopathy is a lethal pathology characterized by oxidative stress, mitochondrial dysfunction, and contractile impairment, leading to cell death. Although extensive research has been done to understand the pathophysiology of doxorubicin cardiomyopathy, no effective treatments are available. We investigated whether monoamine oxidases (MAOs) could be involved in doxorubicin-derived oxidative stress, and in the consequent mitochondrial, cardiomyocyte, and cardiac dysfunction. Results: We used neonatal rat ventricular myocytes (NRVMs) and adult mouse ventricular myocytes (AMVMs). Doxorubicin alone (i.e., 0.5 µM doxorubicin) or in combination with H2O2 induced an increase in mitochondrial formation of reactive oxygen species (ROS), which was prevented by the pharmacological inhibition of MAOs in both NRVMs and AMVMs. The pharmacological approach was supported by the genetic ablation of MAO-A in NRVMs. In addition, doxorubicin-derived ROS caused lipid peroxidation and alterations in mitochondrial function (i.e., mitochondrial membrane potential, permeability transition, redox potential), mitochondrial morphology (i.e., mitochondrial distribution and perimeter), sarcomere organization, intracellular [Ca2+] homeostasis, and eventually cell death. All these dysfunctions were abolished by MAO inhibition. Of note, in vivo MAO inhibition prevented chamber dilation and cardiac dysfunction in doxorubicin-treated mice. Innovation and Conclusion: This study demonstrates that the severe oxidative stress induced by doxorubicin requires the involvement of MAOs, which modulate mitochondrial ROS generation. MAO inhibition provides evidence that mitochondrial ROS formation is causally linked to all disorders caused by doxorubicin in vitro and in vivo. Based upon these results, MAO inhibition represents a novel therapeutic approach for doxorubicin cardiomyopathy.


Assuntos
Doxorrubicina/farmacologia , Ventrículos do Coração/efeitos dos fármacos , Monoaminoxidase/metabolismo , Miócitos Cardíacos/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Animais , Ventrículos do Coração/metabolismo , Camundongos , Mitocôndrias , Miócitos Cardíacos/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Ratos , Espécies Reativas de Oxigênio/análise
6.
ACS Biomater Sci Eng ; 6(10): 5493-5506, 2020 10 12.
Artigo em Inglês | MEDLINE | ID: mdl-33320567

RESUMO

Heart failure is the worst outcome of all cardiovascular diseases and still represents nowadays the leading cause of mortality with no effective clinical treatments, apart from organ transplantation with allogeneic or artificial substitutes. Although applied as the gold standard, allogeneic heart transplantation cannot be considered a permanent clinical answer because of several drawbacks, as the side effects of administered immunosuppressive therapies. For the increasing number of heart failure patients, a biological cardiac substitute based on a decellularized organ and autologous cells might be the lifelong, biocompatible solution free from the need for immunosuppression regimen. A novel decellularization method is here proposed and tested on rat hearts in order to reduce the concentration and incubation time with cytotoxic detergents needed to render acellular these organs. By protease inhibition, antioxidation, and excitation-contraction uncoupling in simultaneous perfusion/submersion modality, a strongly limited exposure to detergents was sufficient to generate very well-preserved acellular hearts with unaltered extracellular matrix macro- and microarchitecture, as well as bioactivity.


Assuntos
Detergentes , Alicerces Teciduais , Matriz Extracelular , Coração , Humanos , Perfusão
7.
Pharmacol Res ; 151: 104548, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31759087

RESUMO

Ischemia/reperfusion (I/R) injury is mediated in large part by opening of the mitochondrial permeability transition pore (PTP). Consequently, inhibitors of the PTP hold great promise for the treatment of a variety of cardiovascular disorders. At present, PTP inhibition is obtained only through the use of drugs (e.g. cyclosporine A, CsA) targeting cyclophilin D (CyPD) which is a key modulator, but not a structural component of the PTP. This limitation might explain controversial findings in clinical studies. Therefore, we investigated the protective effects against I/R injury of small-molecule inhibitors of the PTP (63 and TR002) that do not target CyPD. Both compounds exhibited a dose-dependent inhibition of PTP opening in isolated mitochondria and were more potent than CsA. Notably, PTP inhibition was observed also in mitochondria devoid of CyPD. Compounds 63 and TR002 prevented PTP opening and mitochondrial depolarization induced by Ca2+ overload and by reactive oxygen species in neonatal rat ventricular myocytes (NRVMs). Remarkably, both compounds prevented cell death, contractile dysfunction and sarcomeric derangement induced by anoxia/reoxygenation injury in NRVMs at sub-micromolar concentrations, and were more potent than CsA. Cardioprotection was observed also in adult mouse ventricular myocytes and human iPSc-derived cardiomyocytes, as well as ex vivo in perfused hearts. Thus, this study demonstrates that 63 and TR002 represent novel cardioprotective agents that inhibit PTP opening independent of CyPD targeting.


Assuntos
Cardiotônicos/uso terapêutico , Poro de Transição de Permeabilidade Mitocondrial/antagonistas & inibidores , Traumatismo por Reperfusão Miocárdica/tratamento farmacológico , Bibliotecas de Moléculas Pequenas/uso terapêutico , Animais , Cardiotônicos/farmacologia , Linhagem Celular , Células Cultivadas , Humanos , Camundongos Endogâmicos C57BL , Mitocôndrias Cardíacas/efeitos dos fármacos , Mitocôndrias Cardíacas/metabolismo , Mitocôndrias Cardíacas/patologia , Poro de Transição de Permeabilidade Mitocondrial/metabolismo , Traumatismo por Reperfusão Miocárdica/metabolismo , Traumatismo por Reperfusão Miocárdica/patologia , Miócitos Cardíacos/efeitos dos fármacos , Ratos Sprague-Dawley , Ratos Wistar , Bibliotecas de Moléculas Pequenas/farmacologia
8.
Nature ; 572(7771): 609-613, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31435016

RESUMO

Mitochondria provide chemical energy for endoergonic reactions in the form of ATP, and their activity must meet cellular energy requirements, but the mechanisms that link organelle performance to ATP levels are poorly understood. Here we confirm the existence of a protein complex localized in mitochondria that mediates ATP-dependent potassium currents (that is, mitoKATP). We show that-similar to their plasma membrane counterparts-mitoKATP channels are composed of pore-forming and ATP-binding subunits, which we term MITOK and MITOSUR, respectively. In vitro reconstitution of MITOK together with MITOSUR recapitulates the main properties of mitoKATP. Overexpression of MITOK triggers marked organelle swelling, whereas the genetic ablation of this subunit causes instability in the mitochondrial membrane potential, widening of the intracristal space and decreased oxidative phosphorylation. In a mouse model, the loss of MITOK suppresses the cardioprotection that is elicited by pharmacological preconditioning induced by diazoxide. Our results indicate that mitoKATP channels respond to the cellular energetic status by regulating organelle volume and function, and thereby have a key role in mitochondrial physiology and potential effects on several pathological processes.


Assuntos
Trifosfato de Adenosina/metabolismo , Mitocôndrias Cardíacas/metabolismo , Canais de Potássio/metabolismo , Animais , Cardiotônicos/farmacologia , Diazóxido/farmacologia , Fenômenos Eletrofisiológicos , Coração/efeitos dos fármacos , Coração/fisiologia , Precondicionamento Isquêmico Miocárdico , Masculino , Potencial da Membrana Mitocondrial , Camundongos , Mitocôndrias Cardíacas/efeitos dos fármacos , Mitocôndrias Cardíacas/patologia , Mitocôndrias Cardíacas/fisiologia , Tamanho do Órgão/efeitos dos fármacos , Fosforilação Oxidativa , Potássio/metabolismo , Canais de Potássio/química , Subunidades Proteicas/química , Subunidades Proteicas/metabolismo
9.
Biochim Biophys Acta Mol Basis Dis ; 1864(9 Pt B): 3050-3059, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-29953926

RESUMO

Monoamine oxidase (MAO), a mitochondrial enzyme that oxidizes biogenic amines generating hydrogen peroxide, is a major source of oxidative stress in cardiac injury. However, the molecular mechanisms underlying its overactivation in pathological conditions are still poorly characterized. Here, we investigated whether the enhanced MAO-dependent hydrogen peroxide production can be due to increased substrate availability using a metabolomic profiling method. We identified N1-methylhistamine -the main catabolite of histamine- as an important substrate fueling MAO in Langendorff mouse hearts, directly perfused with a buffer containing hydrogen peroxide or subjected to ischemia/reperfusion protocol. Indeed, when these hearts were pretreated with the MAO inhibitor pargyline we observed N1-methylhistamine accumulation along with reduced oxidative stress. Next, we showed that synaptic terminals are the major source of N1-methylhistamine. Indeed, in vivo sympathectomy caused a decrease of N1-methylhistamine levels, which was associated with a marked protection in post-ischemic reperfused hearts. As far as the mechanism is concerned, we demonstrate that exogenous histamine is transported into isolated cardiomyocytes and triggers a rise in the levels of reactive oxygen species (ROS). Once again, pargyline pretreatment induced intracellular accumulation of N1-methylhistamine along with decrease in ROS levels. These findings uncover a receptor-independent mechanism for histamine in cardiomyocytes. In summary, our study reveals a novel and important pathophysiological causative link between MAO activation and histamine availability during pathophysiological conditions such as oxidative stress/cardiac injury.


Assuntos
Ventrículos do Coração/patologia , Histamina/metabolismo , Monoaminoxidase/metabolismo , Traumatismo por Reperfusão Miocárdica/patologia , Miocárdio/patologia , Animais , Modelos Animais de Doenças , Ventrículos do Coração/citologia , Humanos , Preparação de Coração Isolado , Masculino , Metabolômica , Metilistaminas/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Mitocôndrias/metabolismo , Inibidores da Monoaminoxidase/farmacologia , Traumatismo por Reperfusão Miocárdica/etiologia , Miocárdio/citologia , Miocárdio/metabolismo , Miócitos Cardíacos/citologia , Miócitos Cardíacos/metabolismo , Miócitos Cardíacos/patologia , Oxirredução , Estresse Oxidativo , Pargilina/farmacologia , Espécies Reativas de Oxigênio/metabolismo
10.
Stem Cells Int ; 2017: 8920940, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29250121

RESUMO

Whole heart engineering represents an incredible journey with as final destination the challenging aim to solve end-stage cardiac failure with a biocompatible and living organ equivalent. Its evolution started in 2008 with rodent organs and is nowadays moving closer to clinical application thanks to scaling-up strategies to human hearts. This review will offer a comprehensive examination on the important stages to be reached for the bioengineering of the whole heart, by describing the approaches of organ decellularization, repopulation, and maturation so far applied and the novel technologies of potential interest. In addition, it will carefully address important demands that still need to be satisfied in order to move to a real clinical translation of the whole bioengineering heart concept.

11.
Antioxid Redox Signal ; 23(14): 1106-12, 2015 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-26237157

RESUMO

NADPH oxidases (NOXs) represent the only known dedicated source of reactive oxygen species (ROS) and thus a prime therapeutic target. Type 4 NOX is unique as it produces H2O2, is constitutively active, and has been suggested to localize to cardiac mitochondria, thus possibly linking mitochondrial and NOX-derived ROS formation. The aim of this study was to identify NOX4-binding proteins and examine the possible physiological localization of NOX4 to mitochondria and its impact on mitochondrial ROS formation. We here provide evidence that NOX4 can, in principle, enter protein-protein interactions with mitochondrial complex I NADH dehydrogenase subunits, 1 and 4L. However, under physiological conditions, NOX4 protein was neither detectable in the kidney nor in cardiomyocyte mitochondria. The NOX inhibitor, GKT136901, slightly reduced ROS formation in cardiomyocyte mitochondria, but this effect was observed in both wild-type and Nox4(-/-) mice. NOX4 may thus associate with mitochondrial complex I proteins, but in cardiac and renal mitochondria under basal conditions, expression is beyond our detection limits and does not contribute to ROS formation.


Assuntos
NADPH Oxidases/metabolismo , Animais , Complexo I de Transporte de Elétrons/metabolismo , Limite de Detecção , Camundongos Endogâmicos C57BL , Camundongos Knockout , Mitocôndrias Cardíacas/enzimologia , NADPH Oxidase 4 , Ligação Proteica , Espécies Reativas de Oxigênio/metabolismo , Técnicas do Sistema de Duplo-Híbrido
12.
Cell Metab ; 21(6): 834-44, 2015 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-26039448

RESUMO

Mitochondrial morphological and ultrastructural changes occur during apoptosis and autophagy, but whether they are relevant in vivo for tissue response to damage is unclear. Here we investigate the role of the optic atrophy 1 (OPA1)-dependent cristae remodeling pathway in vivo and provide evidence that it regulates the response of multiple tissues to apoptotic, necrotic, and atrophic stimuli. Genetic inhibition of the cristae remodeling pathway in vivo does not affect development, but protects mice from denervation-induced muscular atrophy, ischemic heart and brain damage, as well as hepatocellular apoptosis. Mechanistically, OPA1-dependent mitochondrial cristae stabilization increases mitochondrial respiratory efficiency and blunts mitochondrial dysfunction, cytochrome c release, and reactive oxygen species production. Our results indicate that the OPA1-dependent cristae remodeling pathway is a fundamental, targetable determinant of tissue damage in vivo.


Assuntos
GTP Fosfo-Hidrolases/metabolismo , Mitocôndrias/metabolismo , Consumo de Oxigênio , Animais , Citocromos c/genética , Citocromos c/metabolismo , GTP Fosfo-Hidrolases/genética , Camundongos , Camundongos Transgênicos , Mitocôndrias/genética , Mitocôndrias/patologia , Atrofia Muscular/genética , Atrofia Muscular/metabolismo , Atrofia Muscular/patologia , Espécies Reativas de Oxigênio/metabolismo
13.
Cardiovasc Res ; 104(1): 93-102, 2014 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-25139744

RESUMO

AIMS: The cellular prion protein, PrP(C), whose aberrant isoforms are related to prion diseases of humans and animals, has a still obscure physiological function. Having observed an increased expression of PrP(C) in two in vivo paradigms of heart remodelling, we focused on isolated mouse hearts to ascertain the capacity of PrP(C) to antagonize oxidative damage induced by ischaemic and non-ischaemic protocols. METHODS AND RESULTS: Hearts isolated from mice expressing PrP(C) in variable amounts were subjected to different and complementary oxidative perfusion protocols. Accumulation of reactive oxygen species, oxidation of myofibrillar proteins, and cell death were evaluated. We found that overexpressed PrP(C) reduced oxidative stress and cell death caused by post-ischaemic reperfusion. Conversely, deletion of PrP(C) increased oxidative stress during both ischaemic preconditioning and perfusion (15 min) with H2O2. Supporting its relation with intracellular systems involved in oxidative stress, PrP(C) was found to influence the activity of catalase and, for the first time, the expression of p66(Shc), a protein implicated in oxidative stress-mediated cell death. CONCLUSIONS: Our data demonstrate that PrP(C) contributes to the cardiac mechanisms antagonizing oxidative insults.


Assuntos
Infarto do Miocárdio/prevenção & controle , Traumatismo por Reperfusão Miocárdica/prevenção & controle , Miócitos Cardíacos/metabolismo , Estresse Oxidativo , Proteínas PrPC/metabolismo , Animais , Catalase/metabolismo , Morte Celular , Modelos Animais de Doenças , Masculino , Camundongos da Linhagem 129 , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteínas Musculares/metabolismo , Infarto do Miocárdio/genética , Infarto do Miocárdio/metabolismo , Infarto do Miocárdio/patologia , Traumatismo por Reperfusão Miocárdica/genética , Traumatismo por Reperfusão Miocárdica/metabolismo , Traumatismo por Reperfusão Miocárdica/patologia , Miócitos Cardíacos/patologia , Proteínas PrPC/deficiência , Proteínas PrPC/genética , Coelhos , Espécies Reativas de Oxigênio/metabolismo , Proteínas Adaptadoras da Sinalização Shc/metabolismo , Proteína 1 de Transformação que Contém Domínio 2 de Homologia de Src , Fatores de Tempo
14.
J Biol Chem ; 289(20): 13769-81, 2014 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-24692541

RESUMO

Translocator protein of 18 kDa (TSPO) is a highly conserved, ubiquitous protein localized in the outer mitochondrial membrane, where it is thought to play a key role in the mitochondrial transport of cholesterol, a key step in the generation of steroid hormones. However, it was first characterized as the peripheral benzodiazepine receptor because it appears to be responsible for high affinity binding of a number of benzodiazepines to non-neuronal tissues. Ensuing studies have employed natural and synthetic ligands to assess the role of TSPO function in a number of natural and pathological circumstances. Largely through the use of these compounds and biochemical associations, TSPO has been proposed to play a role in the mitochondrial permeability transition pore (PTP), which has been associated with cell death in many human pathological conditions. Here, we critically assess the role of TSPO in the function of the PTP through the generation of mice in which the Tspo gene has been conditionally eliminated. Our results show that 1) TSPO plays no role in the regulation or structure of the PTP, 2) endogenous and synthetic ligands of TSPO do not regulate PTP activity through TSPO, 3) outer mitochondrial membrane regulation of PTP activity occurs though a mechanism that does not require TSPO, and 4) hearts lacking TSPO are as sensitive to ischemia-reperfusion injury as hearts from control mice. These results call into question a wide variety of studies implicating TSPO in a number of pathological processes through its actions on the PTP.


Assuntos
Proteínas de Transporte da Membrana Mitocondrial/metabolismo , Membranas Mitocondriais/metabolismo , Receptores de GABA/metabolismo , Animais , Feminino , Deleção de Genes , Fígado/citologia , Fígado/metabolismo , Masculino , Camundongos , Poro de Transição de Permeabilidade Mitocondrial , Miocárdio/citologia , Miocárdio/metabolismo , Permeabilidade , Receptores de GABA/deficiência , Receptores de GABA/genética
15.
Biochim Biophys Acta ; 1813(7): 1323-32, 2011 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-20869994

RESUMO

Recent evidence highlights monoamine oxidases (MAO) as another prominent source of oxidative stress. MAO are a class of enzymes located in the outer mitochondrial membrane, deputed to the oxidative breakdown of key neurotransmitters such as norepinephrine, epinephrine and dopamine, and in the process generate H(2)O(2). All these monoamines are endowed with potent modulatory effects on myocardial function. Thus, when the heart is subjected to chronic neuro-hormonal and/or peripheral hemodynamic stress, the abundance of circulating/tissue monoamines can make MAO-derived H(2)O(2) production particularly prominent. This is the case of acute cardiac damage due to ischemia/reperfusion injury or, on a more chronic stand, of the transition from compensated hypertrophy to overt ventricular dilation/pump failure. Here, we will first briefly discuss mitochondrial status and contribution to acute and chronic cardiac disorders. We will illustrate possible mechanisms by which MAO activity affects cardiac biology and function, along with a discussion as to their role as a prominent source of reactive oxygen species. Finally, we will speculate on why MAO inhibition might have a therapeutic value for treating cardiac affections of ischemic and non-ischemic origin. This article is part of a Special Issue entitled: Mitochondria and Cardioprotection.


Assuntos
Insuficiência Cardíaca/metabolismo , Mitocôndrias Cardíacas/metabolismo , Monoaminoxidase/metabolismo , Traumatismo por Reperfusão Miocárdica/metabolismo , Animais , Cardiomegalia/tratamento farmacológico , Cardiomegalia/metabolismo , Técnicas de Inativação de Genes , Insuficiência Cardíaca/tratamento farmacológico , Insuficiência Cardíaca/patologia , Humanos , Camundongos , Monoaminoxidase/genética , Inibidores da Monoaminoxidase/uso terapêutico , Traumatismo por Reperfusão Miocárdica/patologia , Traumatismo por Reperfusão Miocárdica/prevenção & controle , Miócitos Cardíacos/metabolismo , Miócitos Cardíacos/patologia , Neurotransmissores/metabolismo , Estresse Oxidativo , Espécies Reativas de Oxigênio/metabolismo
16.
Antioxid Redox Signal ; 14(5): 881-91, 2011 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-20615074

RESUMO

Mitochondrial damage is a determining factor in causing loss of cardiomyocyte function and viability, yet a mild degree of mitochondrial dysfunction appears to underlie cardioprotection against injury caused by postischemic reperfusion. This review is focused on two major mechanisms of mitochondrial dysfunction, namely, oxidative stress and opening of the mitochondrial permeability transition pore. The formation of reactive oxygen species in mitochondria will be analyzed with regard to factors controlling mitochondrial permeability transition pore opening. Finally, these mitochondrial processes are analyzed with respect to cardioprotection afforded by ischemic pre- and postconditioning.


Assuntos
Precondicionamento Isquêmico Miocárdico , Mitocôndrias Cardíacas/patologia , Animais , Humanos , Isquemia/metabolismo , Isquemia/fisiopatologia , Mitocôndrias Cardíacas/metabolismo , Proteínas de Transporte da Membrana Mitocondrial/metabolismo , Poro de Transição de Permeabilidade Mitocondrial , Traumatismo por Reperfusão Miocárdica/metabolismo , Traumatismo por Reperfusão Miocárdica/fisiopatologia , Traumatismo por Reperfusão Miocárdica/prevenção & controle , Espécies Reativas de Oxigênio/metabolismo
17.
Biochim Biophys Acta ; 1787(7): 774-80, 2009 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-19362067

RESUMO

Although a major contribution to myocardial ischemia-reperfusion (I/R) injury is suggested to be provided by formation of reactive oxygen species (ROS) within mitochondria, sites and mechanisms are far from being elucidated. Besides a dysfunctional respiratory chain, other mitochondrial components, such as monoamine oxidase and p66(Shc), might be involved in oxidative stress. In particular, p66(Shc) has been shown to catalyze the formation of H(2)O(2). The relationship among p66(Shc), ROS production and cardiac damage was investigated by comparing hearts from p66(Shc) knockout mice (p66(Shc-/-)) and wild-type (WT) littermates. Perfused hearts were subjected to 40 min of global ischemia followed by 15 min of reperfusion. Hearts devoid of p66(Shc) were significantly protected from I/R insult as shown by (i) reduced release of lactate dehydrogenase in the coronary effluent (25.7+/-7.49% in p66(Shc-/-) vs. 39.58+/-5.17% in WT); (ii) decreased oxidative stress as shown by a 63% decrease in malondialdehyde formation and 40+/-8% decrease in tropomyosin oxidation. The degree of protection was independent of aging. The cardioprotective efficacy associated with p66(Shc) ablation was comparable with that afforded by other antioxidant interventions and could not be increased by antioxidant co-administration suggesting that p66(Shc) is downstream of other pathways involved in ROS formation. In addition, the absence of p66(Shc) did not affect the protection afforded by ischemic preconditioning. In conclusion, the absence of p66(Shc) reduces the susceptibility to reperfusion injury by preventing oxidative stress. The present findings provide solid and direct evidence that mitochondrial ROS formation catalyzed by p66(Shc) is causally related to reperfusion damage.


Assuntos
Isquemia/metabolismo , Mitocôndrias Cardíacas/metabolismo , Traumatismo por Reperfusão Miocárdica/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Proteínas Adaptadoras da Sinalização Shc/metabolismo , Animais , Imuno-Histoquímica , L-Lactato Desidrogenase/análise , L-Lactato Desidrogenase/metabolismo , Peroxidação de Lipídeos , Malondialdeído/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Estresse Oxidativo/genética , Estresse Oxidativo/fisiologia , Proteína 1 de Transformação que Contém Domínio 2 de Homologia de Src , Substâncias Reativas com Ácido Tiobarbitúrico/metabolismo , Tropomiosina/imunologia
18.
Pharmacol Rep ; 61(1): 123-30, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19307700

RESUMO

Functional and structural changes in mitochondria are caused by the opening of the mitochondrial permeability transition pore (PTP) and by the mitochondrial generation of reactive oxygen species (ROS). These two processes are linked in a vicious cycle that has been extensively documented in ischemia/reperfusion injuries of the heart, and the same processes likely contribute to vascular pathology. For instance, the opening of the PTP causes cell death in isolated endothelial and vascular smooth muscle cells. Indeed, atherosclerosis is exacerbated when mitochondrial antioxidant defenses are hampered, but a decrease in mitochondrial ROS formation reduces atherogenesis. Determining the exact location of ROS generation in mitochondria is a relevant and still unanswered question. The respiratory chain is generally believed to be a main site of ROS formation. However, several other mitochondrial components likely contribute to ROS generation. Recent reports highlight the relevance of monoamine oxidases (MAO) and p66(Shc). For example, the absence of p66(Shc) in hypercholesterolemic mice has been reported to reduce the occurrence of foam cells and early atherogenic lesions. On the other hand, MAO inhibition has been shown to reduce oxidative stress in many cell types eliciting significant protection from myocardial ischemia. In conclusion, evidence will be presented to demonstrate that (i) mitochondria are major sites of ROS formation; (ii) an increase in mitochondrial ROS formation and/or a decrease in mitochondrial antioxidant defenses exacerbate atherosclerosis; and (iii) mitochondrial dysfunction is likely a relevant mechanism underlying several risk factors (i.e., diabetes, hyperlipidemia, hypertension) associated with atherosclerosis.


Assuntos
Aterosclerose/fisiopatologia , Mitocôndrias/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Animais , Aterosclerose/etiologia , Morte Celular , Humanos , Proteínas de Transporte da Membrana Mitocondrial/metabolismo , Poro de Transição de Permeabilidade Mitocondrial , Monoaminoxidase/efeitos dos fármacos , Monoaminoxidase/metabolismo , Inibidores da Monoaminoxidase/farmacologia , Músculo Liso Vascular/metabolismo , Músculo Liso Vascular/patologia , Estresse Oxidativo , Proteínas Adaptadoras da Sinalização Shc/metabolismo , Proteína 1 de Transformação que Contém Domínio 2 de Homologia de Src
19.
Basic Res Cardiol ; 104(2): 131-9, 2009 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-19242637

RESUMO

Although mitochondria are considered the most relevant site for the formation of reactive oxygen species (ROS) in cardiac myocytes, a major and unsolved issue is where ROS are generated in mitochondria. Respiratory chain is generally indicated as a main site for ROS formation. However, other mitochondrial components are likely to contribute to ROS generation. Recent reports highlight the relevance of monoamine oxidases (MAO) and p66(Shc). The importance of these systems in the irreversibility of ischemic heart injury will be discussed along with the cardioprotective effects elicited by both MAO inhibition and p66(Shc) knockout. Finally, recent evidence will be reviewed that highlight the relevance of mitochondrial ROS formation also in myocardial failure and atherosclerosis.


Assuntos
Mitocôndrias Cardíacas/fisiologia , Monoaminoxidase/metabolismo , Isquemia Miocárdica/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Proteínas Adaptadoras da Sinalização Shc/metabolismo , Transdução de Sinais/fisiologia , Animais , Humanos , Isquemia Miocárdica/fisiopatologia , Proteína 1 de Transformação que Contém Domínio 2 de Homologia de Src
20.
Eur J Pharmacol ; 582(1-3): 26-34, 2008 Mar 17.
Artigo em Inglês | MEDLINE | ID: mdl-18242600

RESUMO

In Jurkat T cells, S-triethylphosphinegold(I)-2,3,4,6-tetra-O-acetyl-1-thio-beta-d-glucopyranoside (auranofin) and triethylphosphine gold(I) chloride (TepAu) induced apoptosis, as estimated by DNA fragmentation and visualised by fluorescence microscopy. Apoptosis was characterised by mitochondrial cytochrome c release which was not prevented by cyclosporin A. Apoptosis appeared to be triggered by inhibition exerted by gold(I) compounds on the cytosolic and mitochondrial isoforms of thioredoxin reductase, which determined a definite increase in hydrogen peroxide, whereas glutathione and its redox state were not modified. Total thiols showed a slight decrease, particularly in the presence of auranofin. However, no significant lipid peroxidation or nitric oxide formation were observed after incubation with gold(I) complexes, indicating that the cells had not been subjected to extensive oxidative stress. Interestingly, the gold(I) compound aurothiomalate was poorly effective, both in inhibiting thioredoxin reductase and in inducing apoptosis. These results demonstrate that the increased production of hydrogen peroxide determines an oxidative shift responsible for the occurrence of apoptosis and not involving lipid peroxidation.


Assuntos
Antirreumáticos/farmacologia , Apoptose , Auranofina/farmacologia , Compostos Organoáuricos/farmacologia , Estresse Oxidativo , Fosfinas/farmacologia , Citocromos c/metabolismo , Humanos , Peróxido de Hidrogênio/metabolismo , Células Jurkat , Peroxidação de Lipídeos/efeitos dos fármacos , Microscopia de Fluorescência , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Tiorredoxina Dissulfeto Redutase/metabolismo
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