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Mitochondrial dysfunctions are responsible for myocardial injury upon ischemia/reperfusion (I/R), and mitochondrial E3 ubiquitin ligase 1 (Mul1) plays an important role in maintaining mitochondrial functions. This study aims to explore the function of Mull in myocardial I/R injury and the underlying mechanisms. The Sprague-Dawley rat hearts were subjected to 1 h of ischemia plus 3 h of reperfusion, which showed the I/R injury (increase in infarct size and creatine kinase release) and the elevated total and mitochondrial protein levels of Mul1 and p53 accompanied by the enhanced interactions between Mul1 and p53 as well as p53 and small a ubiquitin-like modifier (SUMO1). Consistently, hypoxia/reoxygenation (H/R) treated cardiac (H9c2) cells displayed cellular injury (apoptosis and necrosis), upregulation of total and mitochondrial protein levels of Mul1 and p53, and enhanced interactions between p53 and SUMO1 concomitant with mitochondrial dysfunctions (an increase in mitochondrial membrane potential and reactive oxygen species production with a decrease in ATP production); these phenomena were attenuated by knockdown of Mul1 expression. Based on these observations, we conclude that a novel role of Mul1 has been identified in the myocardial mitochondria, where Mul1 stabilizes and activates p53 through its function of SUMOylation following I/R, leading to p53-mediated mitochondrial dysfunction and cell death. Key words: ischemia/reperfusion, myocardial injury, mitochondrial E3 ubiquitin ligase 1, p53, SUMOylation, hypoxia/reoxygenation, mitochondria. Les dysfonctionnements mitochondriaux sont responsables de lesions myocardiques lors de l'ischemie/reperfusion (I/R) et l'E3 ubiquitine ligase mitochondriale 1 (Mul1) joue un role important dans le maintien du fonctionnement des mitochondries. Cette etude portait sur le fonctionnement de la Mul1 dans les lesions d'I/R myocardiques et les modes d'action sous-jacents. Nous avons procede a une ischemie d'une heure suivie d'une reperfusion de trois heures sur des creurs de rats Sprague-Dawley, et observe la presence de lesions d'I/R (augmentation de la taille de l'infarctus et liberation de creatine kinase), l'augmentation des taux de Mul1 et de p53 en proteines totales et mitochondrials, accompagnees de l'augmentation des interactions entre la Mul1 et le p53, ainsi qu'entre le p53 et le petit modificateur ressemblant a l'ubiquitine (ou SUMO1 pour << small ubiquitin-like modifier >>). Les cellules cardiaques H9c2 soumises a l'hypoxie/reoxygenation (H/R) presentaient systematiquement des lesions cellulaires (apoptose et necrose), une regulation a la hausse des taux de Mul1 et de p53 en proteines totales et mitochondriales, avec une augmentation des interactions entre le p53 et le SUMO1 en concomitance avec des dysfonctionnements mitochondriaux (augmentation du potentiel transmembranaire mitochondrial et de la production de derives reactifs de l'oxygene, avec une diminution de la production d'ATP); ces phenomenes s'attenuaient avec la repression de l'expression (<< knockdown >>) du gene Mul1. Sur la foi de ces observations, nous en arrivons a la conclusion que nous avons cerne un nouveau role du gene Mul1 dans la mitochondrie myocardique, par lequel le gene Mul1 entraine une stabilisation et une activation de p53 par l'intermediaire de sa fonction de<< SUMOylation>>consecutive a l'I/R et menant a des dysfonctionnements mitochondriaux et a une mort cellulaire medies par le p53. [Traduit par la Redaction] Mots-cles : ischemie/reperfusion, lesions myocardiques, E3 ubiquitine ligase mitochondriale 1, p53, SUMOylation, hypoxie/ reoxygenation, mitochondrie., Introduction Multiple mechanisms including energy metabolic disorders, calcium overload, oxidative stress, and inflammation are involved in various cardiovascular disorders (Anupama et al. 2018; Kiyuna et al. 2018), all of which [...]

Iron overload triggers the ferroptosis in the heart following ischemia/reperfusion (I/R) and transferrin receptor 1 (TfR1) charges the cellular iron uptake. Bioinformatics analysis shows that the three molecules of ubiquitin-specific protease 7 (USP7), p53 and TfR1 form a unique pathway of USP7/p53/TfR1. This study aims to explore whether USP7/p53/TfR1 pathway promotes ferroptosis in rat hearts suffered I/R and the underlying mechanisms. The SD rat hearts were subjected to 1 h-ischemia plus 3 h-reperfusion, showing myocardial injury (increase in creatine kinase release, infarct size, myocardial fiber loss and disarray) and up-regulation of USP7, p53 and TfR1 concomitant with an increase of ferroptosis (reflecting by accumulation of iron and lipid peroxidation while decrease of glutathione peroxidase activity). Inhibition of USP7 activated p53 via suppressing deubiquitination, which led to down-regulation of TfR1, accompanied by the decreased ferroptosis and myocardial I/R injury. Next, H9c2 cells underwent hypoxia/reoxygenation (H/R) in vitro to mimic the myocardial I/R model in vivo. Consistent with the results in vivo, inhibition or knockdown of USP7 reduced the H/R injury (decrease of LDH release and necrosis) and enhanced the ubiquitination of p53 along with the decreased levels of p53 and TfR1 as well as the attenuated ferroptosis (manifesting as the decreased iron content and lipid peroxidation while the increased GPX activity). Knockdown of TfR1 inhibited H/R-induced ferroptosis without p53 deubiquitination. Based on these observations, we conclude that a novel pathway of USP7/p53/TfR1 has been identified in the I/R-treated rat hearts, where up-regulation of USP7promotes ferrptosis via activation of the p53/TfR1 pathway. Image 1 • The protein levels of USP7, p53 and TfR1 are all elevated in the I/R-treated rat hearts. • Suppression of USP7 mitigate the myocardial I/R injury via reduction of ferroptosis. • USP7 promotes ferroptosis in the I/R-treated hearts via activation of p53/TfR1 pathway. [ABSTRACT FROM AUTHOR]

RIPK1/RIPK3/MLKL (Receptor-interacting protein kinase 1/Receptor-interacting protein kinase 3/Mixed lineage kinase domain-like protein) pathway-mediated necroptosis contributes to myocardial ischemia/reperfusion (I/R) injury, and Arctiin can prevent myocardial fibrosis and hypertrophy. This study aims to explore the effect of Arctiin on myocardial I/R injury and the underlying mechanisms. SD rat hearts or cardiomyocytes were subjected to I/R or hypoxia/reoxygenation (H/R) to establish the I/R or H/R injury model. The methods of biochemistry, PI/DAPI (propidium iodide/4′,6-Diamidino-2-Phenylindole) and H&E (Hematoxylin & eosin) staining were used to evaluate the I/R or H/R injury. The effects of Arctiin on necroptosis in I/R-treated hearts or H/R-treated cardiomyocytes were assessed. The results showed that Arctiin reduced myocardial I/R injury (decreases in myocardial infarction and creatine kinase release), concomitant with a decrease in levels of necroptosis-associated proteins (RIPK1/p-RIPK1, RIPK3/p-RIPK3 and MLKL/p-MLKL) in I/R-treated rat hearts. Consistently, the necrosis and LDH release in H/R-treated cardiomyocytes were attenuated in the presence of Arctiin, accompanied by suppression of necroptosis-relevant proteins. Furthermore, H/R-induced reactive oxygen species (ROS) generation and mitochondrial dysfunctions (increase in mitochondrial membrane potential and decrease in ATP production) were impaired by Arctiin. Using the program of the Molecular Operating Environment (MOE), we predict that RIPK1 and MLKL (but not RIPK3) might be the potential targets of Arctiin. Based on these observations, we conclude that Arctiin can protect the rat heart from I/R injury, and its beneficial effect is related to reduction of necroptosis via scavenging reactive oxygen species and restoring mitochondrial functions or targeting RIPK1 and/or MLKL. Image 1 • Arctiin protects rat heart from myocardial I/R injury. • Arctiin suppresses necroptosis in I/R-treated rat hearts. • Arctiin scavenge ROS and restore mitochondrial functions in cardiomyocyte. [ABSTRACT FROM AUTHOR]

Necroptosis, ferroptosis and cyclophilin D (Cyp D)-dependent necrosis contribute to myocardial ischemia/reperfusion (I/R) injury, and ponatinib, deferoxamine and cyclosporine are reported to inhibit necroptosis, ferroptosis and Cyp D-dependent necrosis, respectively. This study aims to explore whether the any two combination between ponatinib, deferoxamine and cyclosporine exerts a better cardioprotective effect on I/R injury than single medicine does. The H9c2 cells were subjected to 10 h of hypoxia (H) plus 4 h of reoxygenation (R) to establish H/R injury model. The effects of any two combination between ponatinib, deferoxamine and cyclosporine on H/R injury were examined. On this basis, a I/R injury model in rat hearts was established to focus on the effect of ponatinib, deferoxamine and their combination on myocardial I/R injury and the underlying mechanisms. In H/R-treated H9c2 cells, all three medicines can attenuate H/R injury (decrease in LDH release and necrosis percent). However, only the combination of ponatinib with deferoxamine exerted synergistic effect on reducing H/R injury, showing simultaneous suppression of necroptosis and ferroptosis. Expectedly, administration of ponatinib or deferoxamine either before or after ischemia could suppress necroptosis or ferroptosis in the I/R-treated rat hearts as they did in vitro, concomitant with a decrease in myocardial infarct size and creatine kinase release, and the combination therapy is more efficient than single medication. Based on these observations, we conclude that the combination of ponatinib with deferoxamine reduces myocardial I/R injury via simultaneous inhibition of necroptosis and ferroptosis. [Display omitted] [ABSTRACT FROM AUTHOR]

The dysregulation of nuclear factor erythroid 2-related factor 2 (Nrf2) and/or solute carrier family 7 member 11 (SLC7A11) is believed to contribute to ferroptosis in the hearts suffered ischemia/reperfusion (I/R), but the mechanisms behind the dysregulation of them are not fully elucidated. Mucosa associated lymphoid tissue lymphoma translocation gene 1 (MALT1) can function as a paracaspase to cleave specified substrates and it is predicted to interact with Nrf2. This study aims to explore whether targeting MALT1 can reduce I/R-induced ferroptosis via enhancing the Nrf2/SLC7A11 pathway. The SD rat hearts were subjected to 1h-ischemia plus 3h-reperfusion to establish the I/R injury model, which showed myocardial injuries (increase in infarct size and creatine kinase release) and up-regulation of MALT1 while downregulation of Nrf2 and SLC7A11 concomitant with the increased ferroptosis, reflecting by an increase in glutathione peroxidase 4 (GPX4) level while decreases in the levels of acyl-CoA synthetase long chain family member 4 (ACSL4), total iron, Fe2+ and lipid peroxidation (LPO); these phenomena were reversed in the presence of MI-2, a specific inhibitor of MALT1. Consistently, similar results were achieved in the cultured cardiomyocytes subjected to 8h-hypoxia plus 12h-reoxygenation. Furthermore, micafungin, an antifungal drug, could also exert beneficial effect on mitigating myocardial I/R injury via inhibition of MALT1. Based on these observations, we conclud that inhibition of MALT1 can reduce I/R-induced myocardial ferroptosis through enhancing the Nrf2/SLC7A11 pathway; and MALT1 may be used as a potential target to seek novel or existing drugs (such as micafungin) for treating myocardial infarction. [Display omitted] • Upregulation of MALT1 occurs in rat hearts suffered ischemia/reperfusion. • Inhibition of MALT1 reduces I/R-induced ferroptosis via enhancing the Nrf2/SLC7A11 pathway. • Micafungin mitigate myocardial I/R injury via inhibition of MALT1. [ABSTRACT FROM AUTHOR]