Effect of MG53 on Cardiac Function Affected by Acute Doxorubicin-Induced Cardiotoxicity in Mice and Its Mechanism / 中山大学学报(医学科学版)

ObjectiveThis study was designed to explore the effect of MG53 on cardiac function affected by acute doxorubicin （DOX）-induced cardiotoxicity （DIC） in mice and its possible mechanism. MethodsIn vivo， C57BL/6 mice were injected intraperitoneally with twenty mg/kg DOX for one week to induce the acute DIC. In vitro， neonatal rat cardiomyocytes （NRCs） were treated with 1 μmol/L DOX to induce DIC. A small animal ultrasound imaging system was used to evaluate cardiac function， and the left ventricular changes in ejection fraction （EF） and fraction shortening （FS） were measured. qPCR technology was used to evaluate cardiac remodeling related factors ANP， BNP and α-MHC， autophagy-related factors Beclin1 and LC3， and apoptosis-related factor CASPASE3. Autophagy-related protein levels of Beclin1， LC3 and apoptosis-related protein levels of caspase3 were assessed by Western Blot. Transmission electron microscopy （TEM） was used to detect autophagosomes in heart tissues. TUNEL assay kit was used to detect apoptosis in neonatal murine cardiomyocytes. ResultsThe small animal ultrasound imaging revealed cardiac function was significantly reduced by doxorubicin in the DOX group and DOX+AAV9-NC group compared with the sham group （EF： Sham： 86.06 ± 2.08 vs. DOX：58.97 ± 1.62， P < 0.000 1； Sham： 86.06 ± 2.08 vs. DOX+AAV9-NC： 59.00 ± 1.86， P < 0.000 1. FS： Sham： 45.47 ± 1.95 vs. DOX：30.68 ± 1.21， P < 0.000 1； Sham： 45.47 ± 1.95 vs. DOX+AAV9-NC： 30.79 ± 1.13， P < 0.000 1）. However， the overexpression of MG53 with adeno-associated virus9 （AAV9） ameliorated cardiac dysfunction （EF： DOX+AAV9-MG53： 66.93 ± 1.78 vs. DOX+AAV9-NC： 59.00 ± 1.86， P < 0.000 1. FS： DOX+AAV9-MG53： 36.35 ± 1.33 vs. DOX+AAV9-NC： 30.79 ± 1.13， P < 0.000 1）. TEM showed autophagosomes were increased in the DOX+AAV9-MG53 group compared with the DOX group and DOX+AAV9-NC. qPCR results suggested that MG53 down-regulated the mRNA expression of cardiac remodeling related genes. Additionally， Western blot results confirmed that the protein level of caspases3 was decreased and Beclin1 and LC3 expression was increased in the DOX+AAV9-MG53 group compared with those in the DOX group and DOX+AAV9-NC group （caspase： DOX+AAV9-MG53： 1.49 ± 0.13 vs. DOX+AAV9-NC： 2.49 ± 0.46， P = 0.000 2； Beclin-1： DOX+AAV9-MG53：0.82 ± 0.02 vs. DOX+AAV9-NC： 0.62 ± 0.05， P < 0.000 1； LC3： DOX+AAV9-MG53： 0.83 ± 0.04 vs. DOX+AAV9-NC： 0.40 ± 0.05， P < 0.000 1）. In contrast， knockdown of MG53 significantly up-regulated the protein level of Caspase3 and significantly down-regulated the protein level of Beclin1 and LC3 （caspase： DOX+si-MG53： 4.52 ± 0.28 vs. DOX+si-NC： 3.37 ± 0.08， P < 0.000 1； Beclin-1： DOX+si-MG53： 0.34 ± 0.06 vs. DOX+si-NC： 0.54 ± 0.07， P = 0.026 2； LC3： DOX+si-MG53： 0.41 ± 0.12 vs. DOX+si-NC： 0.70 ± 0.07， P = 0.001 5）. TUNEL analysis showed overexpression of MG53 significantly inhibited the apoptosis of cardiomyocytes （DOX+Ad-MG53： 9.41 ± 0.53 vs. DOX+Ad-NC： 29.34 ± 7.29， P < 0.000 1）， and knockdown of MG53 significantly facilitate the apoptosis of cardiomyocytes （DOX+si-MG53： 71.34 ± 5.90 vs. DOX+si-NC： 32.19 ± 9.91， P < 0.000 1）. ConclusionMG53 inhibits cardiac apoptosis and enhances autophagy， which delays cardiac remodeling and ameliorates cardiac dysfunction.

Potentilla anserina polysaccharide alleviates cadmium-induced oxidative stress and apoptosis of H9c2 cells by regulating the MG53-mediated RISK pathway / 中国天然药物

Oxidative stress plays a crucial role in cadmium (Cd)-induced myocardial injury. Mitsugumin 53 (MG53) and its mediated reperfusion injury salvage kinase (RISK) pathway have been demonstrated to be closely related to myocardial oxidative damage. Potentilla anserina L. polysaccharide (PAP) is a polysaccharide with antioxidant capacity, which exerts protective effect on Cd-induced damage. However, it remains unknown whether PAP can prevent and treat Cd-induced cardiomyocyte damages. The present study was desgined to explore the effect of PAP on Cd-induced damage in H9c2 cells based on MG53 and the mediated RISK pathway. For in vitro evaluation, cell viability and apoptosis rate were analyzed by CCK-8 assay and flow cytometry, respectively. Furthermore, oxidative stress was assessed by 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA) staining and using superoxide dismutase (SOD), catalase (CAT), and glutathione/oxidized glutathione (GSH/GSSG) kits. The mitochondrial function was measured by JC-10 staining and ATP detection assay. Western blot was performed to detect the expression of proteins related to MG53, the RISK pathway, and apoptosis. The results indicated that Cd increased the levels of reactive oxygen species (ROS) in H9c2 cells. Cd decreased the activities of SOD and CAT and the ratio of GSH/GSSG, resulting in decreases in cell viability and increases in apoptosis. Interestingly, PAP reversed Cd-induced oxidative stress and cell apoptosis. Meanwhile, Cd reduced the expression of MG53 in H9c2 cells and inhibited the RISK pathway, which was mediated by decreasing the ratio of p-AktSer473/Akt, p-GSK3βSer9/GSK3β and p-ERK1/2/ERK1/2. In addition, Cd impaired mitochondrial function, which involved a reduction in ATP content and mitochondrial membrane potential (MMP), and an increase in the ratio of Bax/Bcl-2, cytoplasmic cytochrome c/mitochondrial cytochrome c, and Cleaved-Caspase 3/Pro-Caspase 3. Importantly, PAP alleviated Cd-induced MG53 reduction, activated the RISK pathway, and reduced mitochondrial damage. Interestingly, knockdown of MG53 or inhibition of the RISK pathway attenuated the protective effect of PAP in Cd-induced H9c2 cells. In sum, PAP reduces Cd-induced damage in H9c2 cells, which is mediated by increasing MG53 expression and activating the RISK pathway.

Effects of contusion and exhaustive exercise on mg53, ptrf in skeletal muscle of rats / Efeitos da contusão e do exercício exaustivo sobre mg53, ptrf em músculos esqueléticos de ratos / Efectos de la contusión y del ejercicio exhaustivo sobre mg53, ptrf en músculos esqueléticos en ratones

ABSTRACT Objectives To study the effects of contusion and exhaustive exercise on gene expression of MG53, PTRF, Pax7 and β-catenin in skeletal muscle of rats, and reveal the repair mechanism of skeletal muscle injury. Methods Forty-two male Wistar rats were randomly divided into 7 groups, with 6 rats in each group. All groups were euthanized at different time points after exhaustive exercise and contusion, respectively, while the control group was euthanized in resting state. The right gastrocnemius muscles were measured for mRNAs of MG53, PTRF, Pax7 and β-catenin by real time PCR. Results MG53 mRNA and PTRF mRNA of skeletal muscle in groups immediately after exhaustive exercise and after contusion increased significantly (p<0.05), while the two indices decreased constantly at 24 and 48 hours after injury with a similar change trend. Compared with the control group, Pax7 mRNA of skeletal muscle as a marker showed no significant difference in exhaustive exercise groups, but decreased at 48 hours after contusion (p<0.05). β-catenin mRNA of skeletal muscle down-regulated significantly over 24 hours after injury, then activated with an increased value at 48 hours after contusion (p<0.05). As a whole, the variations in the above indices in the contusion groups covered a wider range than in the exhaustive exercise groups. Conclusion The cytomembrane repair mechanism of MG53 and PTRF began immediately after the end of exhaustive exercise and contusion. Activation of Pax7 as the satellite cell marker took longer, and Wnt/β-catenin pathway showed first a decrease and then an increase resulting from the time-dependent gene expression during the repair of skeletal muscle injury. Level of evidence III, Therapeutic studies investigating the results of treatment.

RESUMO Objetivos Estudar os efeitos da contusão e do exercício exaustivo sobre a expressão de MG53, PTRF, Pax7 e β-catenina no músculo esquelético de ratos e revelar o mecanismo de reparo da lesão desses músculos. Métodos Quarenta e dois ratos Wistar machos foram divididos randomicamente em 7 grupos, com 6 ratos em cada grupo. Todos os grupos foram sacrificados em diferentes momentos após exercícios exaustivos e contusão, respectivamente, enquanto o grupo controle foi sacrificado em repouso. O músculo gastrocnêmio direito de todos os ratos foi analisado por PCR em tempo real, quanto ao RNAm de MG53, PTRF, Pax7 e β-catenina. Resultados O RNAm de MG53 e de PTRF no músculo esquelético dos grupos imediatamente após o exercício exaustivo e após a contusão aumentou significativamente (p < 0,05), enquanto a diminuição foi constante 24 e 48 horas depois da lesão, com tendência de mudança semelhante. Comparado com o grupo controle, o RNAm de Pax7 do músculo esquelético não mostrou diferença significativa como marcador nos grupos de exercício exaustivo, mas diminuiu 48 horas depois da contusão (p < 0,05). O RNAm da β-catenina do músculo esquelético diminuiu significativamente ao longo de 24 horas após a lesão e, a seguir, voltou para um valor elevado 48 horas depois da contusão (p < 0,05). Como um todo, as variações nos grupos de contusão tiveram uma faixa mais ampla do que a dos grupos de exercícios exaustivos. Conclusões O mecanismo de reparação da citomembrana de MG53 e PTRF começou imediatamente depois do término de exercício exaustivo e contusão. A ativação do Pax7 como marcador das células satélite demorou mais tempo e a via Wnt/β-catenina mostrou primeiro diminuição e depois aumento decorrente da expressão gênica dependente do tempo durante o reparo da lesão muscular esquelética. Nível de Evidência III, Estudos Terapêuticos - Investigação de resultados do tratamento.

RESUMEN Objetivos Estudiar los efectos de la contusión y del ejercicio exhaustivo sobre la expresión de MG53, PTRF, Pax7 y β-catenina en el músculo esquelético de ratones y revelar el mecanismo de reparación de la lesión de esos músculos. Métodos Cuarenta y dos ratones Wistar machos fueron divididos aleatoriamente en 7 grupos, con 6 ratones en cada grupo. Todos los grupos fueron sacrificados en diferentes momentos después de ejercicios exhaustivos y contusión, respectivamente, mientras que el grupo control fue sacrificado en reposo. El músculo gastrocnemio derecho de todos los ratones fue analizado por PCR en tiempo real, cuanto al RNAm de MG53, PTRF, Pax7 y β-catenina. Resultados El RNAm de MG53 y de PTRF en el músculo esquelético de los grupos inmediatamente después del ejercicio exhaustivo y después de la contusión aumentó significativamente (p < 0,05), mientras que la disminución fue constante 24 y 48 horas después de la lesión, con tendencia de cambio semejante. Comparado con el grupo control, el RNAm de Pax7 del músculo esquelético no mostró diferencia significativa como marcador en los grupos de ejercicio exhaustivo, pero disminuyó 48 horas después de la contusión (p < 0,05). El RNAm de la β-catenina del músculo esquelético disminuyó significativamente a lo largo de 24 horas después de la lesión y, a continuación, volvió para un valor elevado 48 horas después de la contusión (p < 0,05). Como un todo, las variaciones en los grupos de contusión tuvieron una franja más amplia que la de los grupos de ejercicios exhaustivos. Conclusiones El mecanismo de reparación de la citomembrana de MG53 y PTRF comenzó inmediatamente después del término de ejercicio exhaustivo y contusión. La activación del Pax7 como marcador de las células satélite demoró más tiempo y la vía Wnt/β-catenina mostró primero disminución y después aumento proveniente de la expresión génica dependiente del tiempo durante la reparación de la lesión muscular esquelética. Nivel de Evidencia III, Estudios Terapéuticos - Investigación de resultados del tratamiento.

Expression levels of sarcolemmal membrane repair proteins following prolonged exercise training in mice.

Membrane repair is a conserved cellular process, where intracellular vesicles translocate to sites of plasma membrane injury to actively reseal membrane disruptions. Such membrane disruptions commonly occur in the course of normal physiology, particularly in skeletal muscles due to repeated contraction producing small tears in the sarcolemmal membrane. Here, we investigated whether prolonged exercise could produce adaptive changes in expression levels of proteins associated with the membrane repair process, including mitsugumin 53/tripartite motif-containing protein 72 (MG53/TRIM72), dysferlin and caveolin-3 (cav3). Mice were exercised using a treadmill running protocol and protein levels were measured by immunoblotting. The specificity of the antibodies used was established by immunoblot testing of various tissue lysates from both mice and rats. We found that MG53/TRIM72 immunostaining on isolated mouse skeletal muscle fibers showed protein localization at sites of membrane disruption created by the isolation of these muscle fibers. However, no significant changes in the expression levels of the tested membrane repair proteins were observed following prolonged treadmill running for eight weeks (30 to 80 min/day). These findings suggest that any compensation occurring in the membrane repair process in skeletal muscle following prolonged exercise does not affect the expression levels of these three key membrane repair proteins.