Modifications post-traductionnelles de la protéine superoxyde dismutase 2 dans le coeur

Nowadays, cardiovascular diseases remain a main public health issue in developed countries. Especially, left ventricular remodeling concerns 30% of patients after myocardial infarction and can lead to heart failure. Left ventricular remodeling and heart failure are associated with oxidative stress, contributing to structural and functional modifications of the heart. The aim of my PhD thesis was to study post-translational modifications of the mitochondrial anti-oxidant enzyme superoxide dismutase 2 (SOD2), especially its acetylation that inactivates it, in the pathophysiological context of cardiovascular diseases.I showed that cardiac SOD2 is inactivated by acetylation on lysin 68, contributing to mitochondrial oxidative stress and mitochondrial dysfunction. Among SIRT isoforms, the mitochondrial protein SIRT3 was identified as responsible for SOD2 deacetylation and subsequent activation, whereas protein acetyl transferase P300 could be involved in SOD2 transcriptional regulation. I also showed that SIRT3-mediated SOD2 activation protects cardiomyocytes from isoproterenol-induced oxidative stress and hypertrophy. These data allowed us to identify SOD2 as a potential molecular target in anti-oxidant therapeutic strategies.I then studied the impact of anti-oxidant molecules MitoQuinone (MitoQ, mitochondrial anti-oxidant) and EUK 134 (SOD mimetic) on cardiomyocytes. I showed that MitoQ and EUK 134 had protective effect on cardiac oxidative stress and hypertrophy. However, MitoQ is associated with mitochondrial dysfunctions and altered mitophagy in cardiomyocytes, contrary to EUK 134 that restore mitochondrial function and maintains mitophagy balance. These data highlight the key role of mitochondrial metabolism in development of anti-oxidant therapeutics.De nos jours, les pathologies cardiovasculaires représentent un enjeu de santé publique majeur dans les pays développés. Particulièrement, le remodelage ventriculaire gauche touche 30% des patients suite à un infarctus du myocarde et peut mener à terme à une insuffisance cardiaque. Le remodelage et l’insuffisance cardiaque sont associés au développement d’un stress oxydant, participant aux modifications structurales et fonctionnelles du coeur. L’objectif de ma thèse consistait en l’étude des modifications post-traductionnelles de la protéine anti-oxydante mitochondriale superoxyde dismutase 2 (SOD2), et plus particulièrement de son inactivation par acétylation, dans le contexte des pathologies cardiovasculaires.J’ai montré que l’inactivation de SOD2 par acétylation de la lysine 68 favorise le stress oxydant et la dysfonction mitochondriale. Parmi les différents isoformes SIRT, la protéine mitochondriale SIRT3 a été identifiée comme responsable de l’activation de SOD2 par désacétylation, tandis que la protéine acetyl transferase P300 serait impliquée dans la régulation transcriptionnelle de SOD2. J’ai également montré que la protéine SIRT3 protège les cardiomyocytes du stress oxydant et de l’hypertrophie induite par stimulation à l’isoprénaline en activant la protéine SOD2. Ces données m’ont permis d’identifier la protéine SOD2 comme cible moléculaire potentielle dans les stratégies thérapeutiques anti-oxydantes.J’ai donc étudié l’impact des anti-oxydants MitoQuinone (MitoQ, antioxydant mitochondrial) et EUK 134 (mimétique des SOD) sur les cardiomyocytes et montré les effets protecteurs de la MitoQ et du EUK 134 sur le stress oxydant et l’hypertrophie. Cependant, la MitoQ entraîne des dysfonctions mitochondriales et un arrêt de la mitophagie délétères pour les cardiomyocytes, contrairement au EUK 134 qui permet de restaurer la fonction mitochondriale en maintenant l’équilibre de la mitophagie. Ces données mettent en évidence le rôle primordial du métabolisme mitochondrial dans le développement des thérapies anti-oxydantes

Superoxide dismutase 2 post-translationnal modifications in the heart

De nos jours, les pathologies cardiovasculaires représentent un enjeu de santé publique majeur dans les pays développés. Particulièrement, le remodelage ventriculaire gauche touche 30% des patients suite à un infarctus du myocarde et peut mener à terme à une insuffisance cardiaque. Le remodelage et l’insuffisance cardiaque sont associés au développement d’un stress oxydant, participant aux modifications structurales et fonctionnelles du coeur. L’objectif de ma thèse consistait en l’étude des modifications post-traductionnelles de la protéine anti-oxydante mitochondriale superoxyde dismutase 2 (SOD2), et plus particulièrement de son inactivation par acétylation, dans le contexte des pathologies cardiovasculaires.J’ai montré que l’inactivation de SOD2 par acétylation de la lysine 68 favorise le stress oxydant et la dysfonction mitochondriale. Parmi les différents isoformes SIRT, la protéine mitochondriale SIRT3 a été identifiée comme responsable de l’activation de SOD2 par désacétylation, tandis que la protéine acetyl transferase P300 serait impliquée dans la régulation transcriptionnelle de SOD2. J’ai également montré que la protéine SIRT3 protège les cardiomyocytes du stress oxydant et de l’hypertrophie induite par stimulation à l’isoprénaline en activant la protéine SOD2. Ces données m’ont permis d’identifier la protéine SOD2 comme cible moléculaire potentielle dans les stratégies thérapeutiques anti-oxydantes.J’ai donc étudié l’impact des anti-oxydants MitoQuinone (MitoQ, antioxydant mitochondrial) et EUK 134 (mimétique des SOD) sur les cardiomyocytes et montré les effets protecteurs de la MitoQ et du EUK 134 sur le stress oxydant et l’hypertrophie. Cependant, la MitoQ entraîne des dysfonctions mitochondriales et un arrêt de la mitophagie délétères pour les cardiomyocytes, contrairement au EUK 134 qui permet de restaurer la fonction mitochondriale en maintenant l’équilibre de la mitophagie. Ces données mettent en évidence le rôle primordial du métabolisme mitochondrial dans le développement des thérapies anti-oxydantes.Nowadays, cardiovascular diseases remain a main public health issue in developed countries. Especially, left ventricular remodeling concerns 30% of patients after myocardial infarction and can lead to heart failure. Left ventricular remodeling and heart failure are associated with oxidative stress, contributing to structural and functional modifications of the heart. The aim of my PhD thesis was to study post-translational modifications of the mitochondrial anti-oxidant enzyme superoxide dismutase 2 (SOD2), especially its acetylation that inactivates it, in the pathophysiological context of cardiovascular diseases.I showed that cardiac SOD2 is inactivated by acetylation on lysin 68, contributing to mitochondrial oxidative stress and mitochondrial dysfunction. Among SIRT isoforms, the mitochondrial protein SIRT3 was identified as responsible for SOD2 deacetylation and subsequent activation, whereas protein acetyl transferase P300 could be involved in SOD2 transcriptional regulation. I also showed that SIRT3-mediated SOD2 activation protects cardiomyocytes from isoproterenol-induced oxidative stress and hypertrophy. These data allowed us to identify SOD2 as a potential molecular target in anti-oxidant therapeutic strategies.I then studied the impact of anti-oxidant molecules MitoQuinone (MitoQ, mitochondrial anti-oxidant) and EUK 134 (SOD mimetic) on cardiomyocytes. I showed that MitoQ and EUK 134 had protective effect on cardiac oxidative stress and hypertrophy. However, MitoQ is associated with mitochondrial dysfunctions and altered mitophagy in cardiomyocytes, contrary to EUK 134 that restore mitochondrial function and maintains mitophagy balance. These data highlight the key role of mitochondrial metabolism in development of anti-oxidant therapeutics

Modifications post-traductionnelles de la protéine superoxyde dismutase 2 dans le coeur

Nowadays, cardiovascular diseases remain a main public health issue in developed countries. Especially, left ventricular remodeling concerns 30% of patients after myocardial infarction and can lead to heart failure. Left ventricular remodeling and heart failure are associated with oxidative stress, contributing to structural and functional modifications of the heart. The aim of my PhD thesis was to study post-translational modifications of the mitochondrial anti-oxidant enzyme superoxide dismutase 2 (SOD2), especially its acetylation that inactivates it, in the pathophysiological context of cardiovascular diseases.I showed that cardiac SOD2 is inactivated by acetylation on lysin 68, contributing to mitochondrial oxidative stress and mitochondrial dysfunction. Among SIRT isoforms, the mitochondrial protein SIRT3 was identified as responsible for SOD2 deacetylation and subsequent activation, whereas protein acetyl transferase P300 could be involved in SOD2 transcriptional regulation. I also showed that SIRT3-mediated SOD2 activation protects cardiomyocytes from isoproterenol-induced oxidative stress and hypertrophy. These data allowed us to identify SOD2 as a potential molecular target in anti-oxidant therapeutic strategies.I then studied the impact of anti-oxidant molecules MitoQuinone (MitoQ, mitochondrial anti-oxidant) and EUK 134 (SOD mimetic) on cardiomyocytes. I showed that MitoQ and EUK 134 had protective effect on cardiac oxidative stress and hypertrophy. However, MitoQ is associated with mitochondrial dysfunctions and altered mitophagy in cardiomyocytes, contrary to EUK 134 that restore mitochondrial function and maintains mitophagy balance. These data highlight the key role of mitochondrial metabolism in development of anti-oxidant therapeutics.De nos jours, les pathologies cardiovasculaires représentent un enjeu de santé publique majeur dans les pays développés. Particulièrement, le remodelage ventriculaire gauche touche 30% des patients suite à un infarctus du myocarde et peut mener à terme à une insuffisance cardiaque. Le remodelage et l’insuffisance cardiaque sont associés au développement d’un stress oxydant, participant aux modifications structurales et fonctionnelles du coeur. L’objectif de ma thèse consistait en l’étude des modifications post-traductionnelles de la protéine anti-oxydante mitochondriale superoxyde dismutase 2 (SOD2), et plus particulièrement de son inactivation par acétylation, dans le contexte des pathologies cardiovasculaires.J’ai montré que l’inactivation de SOD2 par acétylation de la lysine 68 favorise le stress oxydant et la dysfonction mitochondriale. Parmi les différents isoformes SIRT, la protéine mitochondriale SIRT3 a été identifiée comme responsable de l’activation de SOD2 par désacétylation, tandis que la protéine acetyl transferase P300 serait impliquée dans la régulation transcriptionnelle de SOD2. J’ai également montré que la protéine SIRT3 protège les cardiomyocytes du stress oxydant et de l’hypertrophie induite par stimulation à l’isoprénaline en activant la protéine SOD2. Ces données m’ont permis d’identifier la protéine SOD2 comme cible moléculaire potentielle dans les stratégies thérapeutiques anti-oxydantes.J’ai donc étudié l’impact des anti-oxydants MitoQuinone (MitoQ, antioxydant mitochondrial) et EUK 134 (mimétique des SOD) sur les cardiomyocytes et montré les effets protecteurs de la MitoQ et du EUK 134 sur le stress oxydant et l’hypertrophie. Cependant, la MitoQ entraîne des dysfonctions mitochondriales et un arrêt de la mitophagie délétères pour les cardiomyocytes, contrairement au EUK 134 qui permet de restaurer la fonction mitochondriale en maintenant l’équilibre de la mitophagie. Ces données mettent en évidence le rôle primordial du métabolisme mitochondrial dans le développement des thérapies anti-oxydantes

Oxidative Stress in Cardiovascular Diseases

Reactive oxygen species (ROS) are subcellular messengers in signal transductions pathways with both beneficial and deleterious roles. ROS are generated as a by-product of mitochondrial respiration or metabolism or by specific enzymes such as superoxide dismutases, glutathione peroxidase, catalase, peroxiredoxins, and myeloperoxidases. Under physiological conditions, the low levels of ROS production are equivalent to their detoxification, playing a major role in cellular signaling and function. In pathological situations, particularly atherosclerosis or hypertension, the release of ROS exceeds endogenous antioxidant capacity, leading to cell death. At cardiovascular levels, oxidative stress is highly implicated in myocardial infarction, ischemia/reperfusion, or heart failure. Here, we will first detail the physiological role of low ROS production in the heart and the vessels. Indeed, ROS are able to regulate multiple cardiovascular functions, such as cell proliferation, migration, and death. Second, we will investigate the implication of oxidative stress in cardiovascular diseases. Then, we will focus on ROS produced by NAPDH oxidase or during endothelial or mitochondrial dysfunction. Given the importance of oxidative stress at the cardiovascular level, antioxidant therapies could be a real benefit. In the last part of this review, we will detail the new therapeutic strategies potentially involved in cardiovascular protection and currently under study.</jats:p

Oxidative Stress in Cardiovascular Diseases

International audienceReactive oxygen species (ROS) are subcellular messengers in signal transductions pathways with both beneficial and deleterious roles. ROS are generated as a by-product of mitochondrial respiration or metabolism or by specific enzymes such as superoxide dismutases, glutathione peroxidase, catalase, peroxiredoxins, and myeloperoxidases. Under physiological conditions, the low levels of ROS production are equivalent to their detoxification, playing a major role in cellular signaling and function. In pathological situations, particularly atherosclerosis or hypertension, the release of ROS exceeds endogenous antioxidant capacity, leading to cell death. At cardiovascular levels, oxidative stress is highly implicated in myocardial infarction, ischemia/reperfusion, or heart failure. Here, we will first detail the physiological role of low ROS production in the heart and the vessels. Indeed, ROS are able to regulate multiple cardiovascular functions, such as cell proliferation, migration, and death. Second, we will investigate the implication of oxidative stress in cardiovascular diseases. Then, we will focus on ROS produced by NAPDH oxidase or during endothelial or mitochondrial dysfunction. Given the importance of oxidative stress at the cardiovascular level, antioxidant therapies could be a real benefit. In the last part of this review, we will detail the new therapeutic strategies potentially involved in cardiovascular protection and currently under study

Restore mitophagy is essential to prevent cardiac oxidative stress during hypertrophy

Abstract Heart failure, mostly associated with cardiac hypertrophy, is still a major cause of illness and death. Oxidative stress causes contractile failure and the accumulation of reactive oxygen species leads to mitochondrial dysfunction, associated with aging and heart failure, suggesting that mitochondria-targeted therapies could be effective in this context. The purpose of this work was to characterize how mitochondrial oxidative stress is involved in cardiac hypertrophy development and to determine if mitochondria-targeted therapies could improve cardiac phenotypes. We used neonatal and adult rat cardiomyocytes (NCMs and ACMs) hypertrophied by isoproterenol (Iso) to induce an increase of mitochondrial superoxide anion. Superoxide dismutase 2 activity and mitochondrial biogenesis were significantly decreased after 24h of Iso treatment. To counteract the mitochondrial oxidative stress induced by hypertrophy, we evaluated the impact of two different anti-oxidants, mitoquinone (MitoQ) and EUK 134. Both significantly decreased mitochondrial superoxide anion and hypertrophy in hypertrophied NCMs and ACMs. Conversely to EUK 134 which preserved cell functions, MitoQ impaired mitochondrial function by decreasing maximal mitochondrial respiration, mitochondrial membrane potential and mitophagy (particularly Parkin expression) and altering mitochondrial structure. The same decrease of Parkin was found in human cardiomyocytes but not in fibroblasts suggesting a cell specificity deleterious effect of MitoQ. Our data showed the importance of mitochondrial oxidative stress in the development of cardiomyocyte hypertrophy. Interestingly, we observed that targeting mitochondria by an anti-oxidant (MitoQ) impaired metabolism specifically in cardiomyocytes. Conversely, the SOD mimic (EUK 134) decreased both oxidative stress and cardiomyocyte hypertrophy and restored impaired cardiomyocyte metabolism and mitochondrial biogenesis

Desmin aggrephagy in rat and human ischemic heart failure through PKCζ and GSK3β as upstream signaling pathways

International audiencePost-translational modifications of cardiac proteins could participate to left contractile dysfunction resulting in heart failure. Using a rat model of ischemic heart failure, we showed an accumulation of phosphorylated desmin leading to toxic aggregates in cardiomyocytes, but the cellular mechanisms are unknown. The same rat model was used to decipher the kinases involved in desmin phosphorylation and the proteolytic systems present in rat and human failing hearts. We used primary cultures of neonate rat cardiomyocytes for testing specific inhibitors of kinases and for characterizing the autophagic processes able to clear desmin aggregates. We found a significant increase of active PKCζ, no modulation of ubitiquitin-proteasome system, a defect in macroautophagy, and an activation of chaperone-mediated autophagy in heart failure rats. We validated in vitro that PKCζ inhibition induced a significant decrease of GSK3β and of soluble desmin. In vitro activation of ubiquitination of proteins and of chaperone-mediated autophagy is able to decrease soluble and insoluble forms of desmin in cardiomyocytes. These data demonstrate a novel signaling pathway implicating activation of PKCζ in desmin phosphorylation associated with a defect of proteolytic systems in ischemic heart failure, leading to desmin aggrephagy. Our in vitro data demonstrated that ubiquitination of proteins and chaperone-mediated autophagy are required for eliminating desmin aggregates with the contribution of its chaperone protein, α-crystallin Β-chain. Modulation of the kinases involved under pathological conditions may help preserving desmin intermediate filaments structure and thus protect the structural integrity of contractile apparatus of cardiomyocytes by limiting desmin aggregates formation

Desmin aggrephagy in rat and human ischemic heart failure through PKCζ and GSK3β as upstream signaling pathways

AbstractPost-translational modifications of cardiac proteins could participate to left contractile dysfunction resulting in heart failure. Using a rat model of ischemic heart failure, we showed an accumulation of phosphorylated desmin leading to toxic aggregates in cardiomyocytes, but the cellular mechanisms are unknown. The same rat model was used to decipher the kinases involved in desmin phosphorylation and the proteolytic systems present in rat and human failing hearts. We used primary cultures of neonate rat cardiomyocytes for testing specific inhibitors of kinases and for characterizing the autophagic processes able to clear desmin aggregates. We found a significant increase of active PKCζ, no modulation of ubitiquitin-proteasome system, a defect in macroautophagy, and an activation of chaperone-mediated autophagy in heart failure rats. We validated in vitro that PKCζ inhibition induced a significant decrease of GSK3β and of soluble desmin. In vitro activation of ubiquitination of proteins and of chaperone-mediated autophagy is able to decrease soluble and insoluble forms of desmin in cardiomyocytes. These data demonstrate a novel signaling pathway implicating activation of PKCζ in desmin phosphorylation associated with a defect of proteolytic systems in ischemic heart failure, leading to desmin aggrephagy. Our in vitro data demonstrated that ubiquitination of proteins and chaperone-mediated autophagy are required for eliminating desmin aggregates with the contribution of its chaperone protein, α-crystallin Β-chain. Modulation of the kinases involved under pathological conditions may help preserving desmin intermediate filaments structure and thus protect the structural integrity of contractile apparatus of cardiomyocytes by limiting desmin aggregates formation.</jats:p

Restore mitophagy is essential to prevent cardiac oxidative stress during hypertrophy

AbstractHeart failure, mostly associated with cardiac hypertrophy, is still a major cause of illness and death. Oxidative stress causes contractile failure and the accumulation of reactive oxygen species leads to mitochondrial dysfunction, associated with aging and heart failure, suggesting that mitochondria-targeted therapies could be effective in this context. The purpose of this work was to characterize how mitochondrial oxidative stress is involved in cardiac hypertrophy development and to determine if mitochondria-targeted therapies could improve cardiac phenotypes. We used neonatal and adult rat cardiomyocytes (NCMs and ACMs) hypertrophied by isoproterenol (Iso) to induce an increase of mitochondrial superoxide anion. Superoxide dismutase 2 activity and mitochondrial biogenesis were significantly decreased after 24h of Iso treatment. To counteract the mitochondrial oxidative stress induced by hypertrophy, we evaluated the impact of two different anti-oxidants, mitoquinone (MitoQ) and EUK 134. Both significantly decreased mitochondrial superoxide anion and hypertrophy in hypertrophied NCMs and ACMs. Conversely to EUK 134 which preserved cell functions, MitoQ impaired mitochondrial function by decreasing maximal mitochondrial respiration, mitochondrial membrane potential and mitophagy (particularly Parkin expression) and altering mitochondrial structure. The same decrease of Parkin was found in human cardiomyocytes but not in fibroblasts suggesting a cell specificity deleterious effect of MitoQ. Our data showed the importance of mitochondrial oxidative stress in the development of cardiomyocyte hypertrophy. Interestingly, we observed that targeting mitochondria by an anti-oxidant (MitoQ) impaired metabolism specifically in cardiomyocytes. Conversely, the SOD mimic (EUK 134) decreased both oxidative stress and cardiomyocyte hypertrophy and restored impaired cardiomyocyte metabolism and mitochondrial biogenesis.</jats:p

Mitochondrial-Targeted Therapies Require Mitophagy to Prevent Oxidative Stress Induced by SOD2 Inactivation in Hypertrophied Cardiomyocytes

Heart failure, mostly associated with cardiac hypertrophy, is a major cause of illness and death. Oxidative stress causes accumulation of reactive oxygen species (ROS), leading to mitochondrial dysfunction, suggesting that mitochondria-targeted therapies could be effective in this context. The purpose of this work was to determine whether mitochondria-targeted therapies could improve cardiac hypertrophy induced by mitochondrial ROS. We used neonatal (NCMs) and adult (ACMs) rat cardiomyocytes hypertrophied by isoproterenol (Iso) to induce mitochondrial ROS. A decreased interaction between sirtuin 3 and superoxide dismutase 2 (SOD2) induced SOD2 acetylation on lysine 68 and inactivation, leading to mitochondrial oxidative stress and dysfunction and hypertrophy after 24 h of Iso treatment. To counteract these mechanisms, we evaluated the impact of the mitochondria-targeted antioxidant mitoquinone (MitoQ). MitoQ decreased mitochondrial ROS and hypertrophy in Iso-treated NCMs and ACMs but altered mitochondrial structure and function by decreasing mitochondrial respiration and mitophagy. The same decrease in mitophagy was found in human cardiomyocytes but not in fibroblasts, suggesting a cardiomyocyte-specific deleterious effect of MitoQ. Our data showed the importance of mitochondrial oxidative stress in the development of cardiomyocyte hypertrophy. We observed that targeting mitochondria by MitoQ in cardiomyocytes impaired the metabolism through defective mitophagy, leading to accumulation of deficient mitochondria.</jats:p