Cardiomyocyte Apoptosis Research Articles

Hypoxia and re-oxygenation effects on human cardiomyocytes cultured on polycaprolactone and polyurethane nanofibrous mats

Heart diseases are caused mainly by chronic oxygen insufficiency (hypoxia), leading to damage and apoptosis of cardiomyocytes. Research into the regeneration of a damaged human heart is limited due to the lack of cellular models that mimic damaged cardiac tissue. Based on the literature, nanofibrous mats affect the cardiomyocyte morphology and stimulate the growth and differentiation of cells cultured on them; therefore, nanofibrous materials can support the production of in vitro models that faithfully mimic the 3D structure of human cardiac tissue. Nanofibrous mats were used as scaffolds for adult primary human cardiomyocytes (HCM) and immature human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs). This work focuses on understanding the effects of hypoxia and re-oxygenation on human cardiac cells cultured on polymer nanofibrous mats made of poly(ε-caprolactone) (PCL) and polyurethane (PU). The expression of selected genes and proteins in cardiomyocytes during hypoxia and re-oxygenation were evaluated. In addition, the type of cell death was analyzed. To the best of our knowledge, there are no studies on the effects of hypoxia on cardiomyocyte cells cultured on nanofibrous mats. The present study aimed to use nanofiber mats as scaffolds that structurally could mimic cardiac extracellular matrix. Understanding the impact of 3D structural properties in vitro cardiac models on different human cardiomyocytes is crucial for advancing cardiac tissue engineering and regenerative medicine. Observing how 3D scaffolds affect cardiomyocyte function under hypoxic conditions is necessary to understand the functioning of the entire human heart.

Increased PHLPP1 expression through ERK-4E-BP1 signaling axis drives nicotine induced oxidative stress related damage of cardiomyocytes

Nicotine, a key constituent of tobacco/electronic cigarettes causes cardiovascular injury and mortality. Nicotine is known to induce oxidative stress and mitochondrial dysfunction in cardiomyocytes leading to cell death. However, the underlying mechanisms remain unclear. Pleckstrin homology domain leucine-rich repeat protein phosphatase (PHLPP) is a member of metal-dependent protein phosphatase (PPM) family and is known to dephosphorylate several AGC family kinases and thereby regulate a diverse set of cellular functions including cell growth, survival, and death. Our lab has previously demonstrated that PHLPP1 removal reduced cardiomyocyte death and cardiac dysfunction following injury. Here, we present a novel finding that nicotine exposure significantly increased PHLPP1 protein expression in the adolescent rodent heart. Building upon our in vivo finding, we determined the mechanism of PHLPP1 expression in cardiomyocytes. Nicotine significantly increased PHLPP1 protein expression without altering PHLPP2 in cardiomyocytes. In cardiomyocytes, nicotine significantly increased NADPH oxidase 4 (NOX4), which coincided with increased reactive oxygen species (ROS) and increased cardiomyocyte apoptosis which were dependent on PHLPP1 expression. PHLPP1 expression was both necessary and sufficient for nicotine induced mitochondrial dysfunction. Mechanistically, nicotine activated extracellular signal-regulated protein kinases (ERK1/2) and subsequent eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1) to increase PHLPP1 protein expression. Inhibition of protein synthesis with cycloheximide (CHX) and 4EGI-1 abolished nicotine induced PHLPP1 protein expression. Moreover, inhibition of ERK1/2 activity by U0126 significantly blocked nicotine induced PHLPP1 expression. Overall, this study reveals a novel mechanism by which nicotine regulates PHLPP1 expression through ERK-4E-BP1 signaling axis to drive cardiomyocyte injury.

Hypoxia triggers cardiomyocyte apoptosis via regulating the m6A methylation-mediated LncMIAT/miR-708-5p/p53 axis

Long-time hypoxia induced cardiomyocyte apoptosis is an important mechanism of myocardial ischemia (MI) injury. Interestingly, long noncoding RNA myocardial infarction-associated transcript (LncMIAT) has been involved in the regulation of MI injury; however, the underlying mechanism by which LncMIAT affects the progression of hypoxia-induced cardiomyocyte apoptosis remains unclear. In the present study, hypoxia was found to promote cardiomyocyte apoptosis through an increased expression of LncMIAT in vitro. Biological investigations and dual-luciferase gene reporter assay further revealed that LncMIAT was able to bind with miR-708-5p to upregulate the p53-mediated cell death of the cardiomyocytes. Silencing of LncMIAT or overexpression of miR-708-5p led to a significant reduction in p53-mediated cardiomyocyte apoptosis. The methylated RNA immunoprecipitation (MeRIP)-qPCR results showed that hypoxia exerted its effects on LncMIAT through AKLBH5-N6-methyladenosine (m6A) methylation and therefore hypoxia was shown to trigger HL-1 cardiomyocyte apoptosis via the m6A methylation-mediated LncMIAT/miR-708-5p/p53 axis. Silencing of AKLBH5 significantly alleviated the m6A methylation-mediated LncMIAT upregulation and p53-mediated cardiomyocyte apoptosis, while promoted miR-708-5p expression. Taken together, the present study highlighted that LncMIAT could act as a key biological target during hypoxia-induced cardiomyocyte apoptosis. In addition, it was shown that hypoxia could promote cardiomyocyte apoptosis through regulation of the m6A methylation-mediated LncMIAT/miR-708-5p/p53 signaling axis.

MiR-92a-3p regulates ethanol-induced apoptosis in H9c2 cardiomyocytes.

The role of miR-92a-3p in the ethanol-induced apoptosis of H9c2 cardiomyocytes remains unclear. In this study, we explored the role of miR-92a-3p in the ethanol-induced apoptosis of H9c2 cardiomyocytes and identified its target genes and signaling pathways. H9c2 cells were cultured with or without 100mM ethanol for 24h. The differential expression of miR-92a-3p was verified in H9c2 cells through reverse transcription-quantitative polymerase chain reaction (RT-qPCR). To manipulate the expression of miR-92a-3p, both a mimic and an inhibitor were transfected into H9c2 cells. An Annexin V-fluorescein isothiocyanate/propidium iodide apoptosis detection kit and apoptosis-related antibodies were used for apoptosis detection through flow cytometry and Western blotting, respectively. Target genes were verified through RT-qPCR, Western blotting, and double luciferase reporter gene assays. miR-92a-3p was significantly overexpressed in ethanol-stimulated H9c2 cardiomyocytes (P<0.001). After ethanol stimulation, H9c2 myocardial cells exhibited increased apoptosis. The apoptosis rate was higher in the miR-92a-3p mimic group than in the control group. However, the apoptosis rate was lower in the miR-92a-3p inhibitor group than in the control group, indicating that miR-92a-3p promotes the ethanol-induced apoptosis of H9c2 myocardial cells. RT-qPCR and Western blotting revealed that the miR-92a-3p mimic and inhibitor significantly regulated the mRNA and protein expression levels of mitogen- and stress-activated protein kinase 2 and cyclic AMP-responsive element-binding protein 3-like protein 2 (CREB3L2), suggesting that miR-92a-3p promotes the apoptosis of H9c2 cardiomyocytes by inhibiting the MSK2/CREB/Bcl-2 pathway. Therefore, the apoptosis of H9c2 cardiomyocytes increases after ethanol stimulation, and miR-92a-3p can directly target MSK2 and CREB3L2, thereby promoting the ethanol-induced apoptosis of H9c2 myocardial cells.

Pterostilbene-Loaded Polydopamine Nanoparticles Down-Regulate Tumor Necrosis Factor-α and Improve Myocardial Function in Mice with Acute Myocardial Infarction

TNF-α expression is related to myocardial function damage and recovery in patients with acute myocardial infarction, but its mechanism is not clear. 50 SD mice, 10 in each group, were in this study divided into TNF-α group, Notch1/eIF3a agonist group, model group, positive control group, and control group. The cardiac function score, myocardial infarction volume, myocardial cell apoptosis index, TNF-α expression, and Notch1/eIF3a pathway factor expression were observed. The size of polydopamine nanoparticles carrying pterostilbene was about 15.5 nm, and cardiac function score, myocardial infarction volume, myocardial cell apoptosis index, and myocardial cell apoptosis number in the model group and Notch1/eIF3a agonist group were higher than model group and Notch1/eIF3a agonist group (P &lt; 0.05). Compared with model group, the Notch1/eIF3a agonist group, TNF-α group, and positive control group showed no differences (P &gt; 0.05). The model group and Notch1/eIF3a agonist group had highest inflammatory response and lowest oxidative stress, which were significantly different from other groups (P &lt; 0.05). The expression of TNF-α in Notch1/eIF3a agonist group, model group, and positive control group all decreased, which was significantly different from other groups (P &lt; 0.05). The expressions of p-IL-6 and p-eIF3a in model group, Notch1/eIF3a agonist group and positive control group were all highest (P &lt; 0.05). Carrying Pterostilbene-loaded polydopamine nanoparticles (PPNs) therefore inhibits apoptosis of cardiomyocytes, Notch1/eIF3a signaling pathway and inflammatory response and oxidative stress of myocardial system, and protects cardiomyocytes of model mice.

Alcohol exposure during pregnancy induces cardiac mitochondrial damage in offspring mice.

Prenatal alcohol exposure (PAE) has been linked to congenital heart disease and fetal alcohol syndrome. The heart primarily relies on mitochondria to generate energy, so impaired mitochondrial function due to alcohol exposure can significantly affect cardiac development and function. Our study aimed to investigate the impact of PAE on myocardial and mitochondrial functions in offspring mice. We administered 30% alcohol (3 g/kg) to pregnant C57BL/6 mice during the second trimester. We assessed cardiac function by transthoracic echocardiography, observed myocardial structure and fibrosis through staining tests and electron transmission microscopy, and detected cardiomyocyte apoptosis with dUTP nick end labeling assay and real-time quantitative PCR. Additionally, we measured the reactive oxygen species content, ATP level, and mitochondrial DNA copy number in myocardial mitochondria. Mitochondrial damage was evaluated by assessing the level of mitochondrial membrane potential and the opening degree of mitochondrial permeability transition pores. Our findings revealed that PAE caused cardiac systolic dysfunction, ventricular enlargement, thinned ventricular wall, cardiac fibrosis in the myocardium, scattered loss of cardiomyocytes, and disordered arrangement of myocardial myotomes in the offspring. Furthermore, we observed a significant increase in mitochondrial reactive oxygen species content, a decrease in mitochondrial membrane potential, ATP level, and mitochondrial DNA copy number, and sustained opening of mitochondrial permeability transition pores in the heart tissues of the offspring. These results indicated that PAE had adverse effects on the cardiac structure and function of the newborn mice and could trigger oxidative stress in their myocardia and contribute to mitochondrial dysfunction.

Genistein alleviates doxorubicin-induced cardiomyocyte autophagy and apoptosis via ERK/STAT3/c-Myc signaling pathway in rat model.

Doxorubicin (Dox) is a highly effective anti-neoplastic agent. Still, its utility in the clinic has been hindered by toxicities, including vomiting, hematopoietic suppression and nausea, with cardiotoxicity being the most serious side effect. Genistein (Gen) is a natural product with extensive biological effects, including anti-oxidation, anti-tumor, and cardiovascular protection. This study evaluated whether Gen protected the heart from Dox-induced cardiotoxicity and explored the underlying mechanisms. Male Sprague-Dawley (SD) rats were categorized into control (Ctrl), genistein (Gen), doxorubicin (Dox), genistein 20 mg/kg/day + doxorubicin (Gen20 + Dox) and genistein 40 mg/kg/day + doxorubicin (Gen40 + Dox) groups. Six weeks after injection, immunohistochemistry (IHC), transmission electron microscopy (TEM), and clinical cardiac function analyses were performed to evaluate the effects of Dox on cardiac function and structural alterations. Furthermore, each heart histopathological lesions were given a score of 0-3 in compliance with the articles for statistical analysis. In addition, molecular and cellular response of H9c2 cells toward Dox were evaluated through western blotting, Cell Counting Kit-8 (CCK8), AO staining and calcein AM/PI assay. Dox (5 μM in vitro and 18 mg/kg in vivo) was used in this study. In vivo, low-dose Gen pretreatment protected the rat against Dox-induced cardiac dysfunction and pathological remodeling. Gen inhibited extracellular signal-regulated kinase1/2 (ERK1/2)'s phosphorylation, increased the protein levels of STAT3 and c-Myc, and decreased the autophagy and apoptosis of cardiomyocytes. U0126, a MEK1/2 inhibitor, can mimic the effect of Gen in protecting against Dox-induced cytotoxicity both in vivo and in vitro. Molecular docking analysis showed that Gen forms a stable complex with ERK1/2. Gen protected the heart against Dox-induced cardiomyocyte autophagy and apoptosis through the ERK/STAT3/c-Myc signaling pathway.

Liraglutide ameliorates TAC-induced cardiac hypertrophy and heart failure by upregulating expression level of ANP expression

Recent studies have underscored the cardioprotective properties of liraglutide. This research explores its impact on cardiac hypertrophy and heart failure following transverse aortic constriction (TAC). We found that liraglutide administration markedly ameliorated cardiac hypertrophy, fibrosis, and function. These benefits correlated with increased ANP expression and reduced activity in the calcineurin A/NFATc3 signaling pathway. Moreover, liraglutide mitigated ER stress and cardiomyocyte apoptosis, and enhanced autophagy. Notably, the positive effects of liraglutide diminished when co-administered with A71915, an ANP inhibitor, suggesting that ANP upregulation is critical to its cardioprotective mechanism.

Myclobutanil induces cardiotoxicity in developing zebrafish larvae by initiating oxidative stress and apoptosis: The protective role of curcumin

Myclobutanil (MYC) is a common triazole fungicide widely applied in agriculture. MYC extensively exists in the natural environment and can be detected in organisms. However, little is known about MYC-induced embryonic developmental damage. This study aimed to unravel the cardiotoxicity of MYC and the underlying mechanisms, as well as the cardioprotective effect of curcumin (CUR, an antioxidant polyphenol) using the zebrafish model. Here, zebrafish embryos were exposed to MYC at concentrations of 0, 0.5, 1 and 2 mg/L from 4 to 96 h post fertilization (hpf) and cardiac development was assessed. As results, MYC reduced the survival and hatching rate, body length and heart rate, but increased the malformation rate and spontaneous movement. MYC caused abnormal cardiac morphology and function in myl7:egfp transgenic zebrafish, and downregulated cardiac developmental genes. MYC promoted oxidative stress through excessive reactive oxygen species (ROS) accumulation and suppressed the activities of antioxidant enzymes, triggering cardiomyocytic apoptosis via upregulated expression of apoptosis-related genes. These adverse toxicities could be significantly ameliorated by the antioxidant properties of CUR, indicating that CUR rescued MYC-induced cardiotoxicity by inhibiting oxidative stress and apoptosis. Overall, our study revealed the potential mechanisms of oxidative stress and apoptosis in MYC-induced cardiotoxicity in zebrafish and identified the cardioprotection of CUR in this pathological process.

Liraglutide Protects Cardiomyocytes against Isoprenaline-Induced Apoptosis in Experimental Takotsubo Syndrome.

Takotsubo syndrome (TTS) is a stress-induced cardiomyopathy, characterized by an increased concentration of catecholamines, free radicals, and inflammatory cytokines, endothelial dysfunction, and increased apoptotic activity. High doses of isoprenaline are used in animal models to induce Takotsubo (TT)-like myocardial injury. The aim of the study was to investigate the antiapoptotic effects of liraglutide in experimental TTS and its role in the NF-κB pathway. Wistar rats were pretreated with liraglutide for 10 days, and on days 9 and 10, TT-like myocardial injury was induced with isoprenaline. After the sacrifice on day 11, hearts were isolated for histopathological and immunohistochemical analysis. Liraglutide reduced isoprenaline-induced cardiomyocyte apoptosis by decreasing cleaved caspase-3 (CC3), BCL-2-associated X protein (BAX), and NF-κB and increasing B-cell lymphoma/leukemia-2 (BCL-2). An increase in NF-κB in isoprenaline-treated rats was in positive correlation with proapoptotic markers (BAX and CC3) and in negative correlation with antiapoptotic marker BCL-2. Liraglutide increased BCL-2 and decreased NF-κB, BAX, and CC3, preserving the same correlations of NF-κB to apoptotic markers. It is concluded that liraglutide protects cardiomyocytes against isoprenaline-induced apoptosis in experimental TT-like myocardial injury through downregulation of the NF-κB pathway.

Differential sex-dependent role of lncRNAs in cardiomyopathy

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Ministry of Education and Science Cardiovascular diseases are one of the most prevalent causes of mortality and morbidity worldwide. Structural diseases such as dilated and hypertrophic cardiomyopathy significantly contributed to it. In recent years, several studies have pinpointed the importance of non-coding genome in the pathogenesis of cardiomyopathy. We have previously reported the role of distinct lncRNAs in atrial fibrillation. We now explored the plausible role of these lncRNAs in cardiomyopathy by analyzing their expression in two different mouse mutant models of lamin (LMNA) - LMNAR249W and αMHCCreLMNAFF, a cardiac hypertrophic MyBPC3 mutant model as well as in experimental myocardial infarction mice. Importantly, both LMNA mutant models developed a dilated cardiomyopathy, a condition distinctly observed in males but not in females. Our data demonstrated that Walras, Gm26533, Wallrd, Walaa and Walrad are downregulated in females, but not males. Furthermore, differential deregulation is also observed in MyBPC3 mutant model but not in myocardial infarction. In vitro analyses demonstrated an estrogen-dependent regulation. In addition, expression analyses in distinct cardiovascular cell lines revealed enriched myocardial expression of Walras and Gm26533 while Wallrd and Walaa are preferentially expressed in endocardial cells. These data were further validated by in situ hybridization in embryonic cardiac tissues. Walras overexpression resulted in enhanced expression of two key factors of UPR signaling pathway, i.e. Atf6 and Ire1, while Walras inhibition downregulated them. Upregulation of both UPR factors in Walrasgain-of-function assays is accompanied by increased cardiomyocyte apoptosis. In contrast, Walras inhibition resulted in increased Bcl2 expression and therefore increased cell viability. Mechanistically, Walras directly interacts with calumenin protein, a known protective factor against UPR-associated apoptosis, as demonstrated by pulldown assays. In sum, we demonstrated sex-dependent regulation of distinct lncRNAs in different cardiomyopathic mouse models and at least one of them, i.e. Walras contributes to UPR-associated apoptosis regulation, providing a causative link to the development of distinct cardiomyopathies.

Reversal of lipopolysaccharide-induced cardiomyocyte apoptosis via α7nAChR by dexmedetomidine.

This study aims to analyze the reversal of lipopolysaccharide (LPS)-induced cardiomyocyte apoptosis via α7nAChR by dexmedetomidine (Dex), so as to provide references for clinical treatment of myocardial disorders in the future. First, the research team divided cardiomyocytes (H9C2) were divided into a control group (normal culture), an LPS group (LPS-induced injury model), and an experimentalgroup (pretreated with Dex before LPS induction). Subsequently, lactate dehydrogenase (LDH) and cell activity were detected, and the research team found that the LDH content of the control, experimental and LPS groups were in ascending order (P<0.05). The cell viability decreased and apoptosis increased in the LPS group, with cells mainly concentrating in the G2-M phase; the viability increased and apoptosis decreased in the experimental group, with blocked G1-G0 phase (P<0.05).This demonstrates that Dex can reverse LPS-induced apoptosis in cardiomyocytes. Subsequently, the research group also detected the expression of α7nAChR and NF-κB/AKT pathway, and it was seen that the expression of α7nAChR in the LPS group was higher than that in the control group, with activated NF-κB/AKT pathway; the α7nAChR expression in the experimental group was further elevated, but the NF-κB/AKT pathway was inhibited (P<0.05). The effects of Dex on cardiomyocytes were seen to be related to the α7nAChR and NF-κB/AKT pathways.

Inhibition of phosphodiesterase 4 attenuates myocardial ischemia/reperfusion injury by inhibiting cardiomyocytes apoptosis

Inhibition of phosphodiesterase 4 attenuates myocardial ischemia/reperfusion injury by inhibiting cardiomyocytes apoptosis

DEAD-box helicase 17 (DDX17) protects cardiac function by promoting mitochondrial homeostasis in heart failure

DEAD-box helicase 17 (DDX17) is a typical member of the DEAD-box family with transcriptional cofactor activity. Although DDX17 is abundantly expressed in the myocardium, its role in heart is not fully understood. We generated cardiomyocyte-specific Ddx17-knockout mice (Ddx17-cKO), cardiomyocyte-specific Ddx17 transgenic mice (Ddx17-Tg), and various models of cardiomyocyte injury and heart failure (HF). DDX17 is downregulated in the myocardium of mouse models of heart failure and cardiomyocyte injury. Cardiomyocyte-specific knockout of Ddx17 promotes autophagic flux blockage and cardiomyocyte apoptosis, leading to progressive cardiac dysfunction, maladaptive remodeling and progression to heart failure. Restoration of DDX17 expression in cardiomyocytes protects cardiac function under pathological conditions. Further studies showed that DDX17 can bind to the transcriptional repressor B-cell lymphoma 6 (BCL6) and inhibit the expression of dynamin-related protein 1 (DRP1). When DDX17 expression is reduced, transcriptional repression of BCL6 is attenuated, leading to increased DRP1 expression and mitochondrial fission, which in turn leads to impaired mitochondrial homeostasis and heart failure. We also investigated the correlation of DDX17 expression with cardiac function and DRP1 expression in myocardial biopsy samples from patients with heart failure. These findings suggest that DDX17 protects cardiac function by promoting mitochondrial homeostasis through the BCL6-DRP1 pathway in heart failure.

SP1 MEDIATES OGD/R-INDUCED CARDIOMYOCYTE INJURY VIA ENHANCING THE TRANSCRIPTION OF USP46.

Background: One of the mechanisms responsible for the high mortality rate of acute myocardial infarction is myocardial ischemia-reperfusion injury (MI-RI). The present study focused on the role and regulatory mechanisms of specificity protein 1 (SP1) and ubiquitin-specific protease 46 (USP46) in oxygen-glucose deprivation/reperfusion (OGD/R)-induced cardiomyocyte injury. Methods: OGD/R was used to treat cardiomyocytes AC16 to mimic ischemia-reperfusion in vitro . Cell viability, proliferation, and apoptosis were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, 5-ethynyl-2'-deoxyuridine, and flow cytometry assays. Enzyme-linked immunosorbent assays analyzed the concentrations of TNF-α and IL-1β. Several protein levels were analyzed by western blotting. The levels of iron (Fe 2+ ), reactive oxygen species, malondialdehyde, and the activities of superoxide dismutase were analyzed by commercial kits. Chromatin immunoprecipitation and dual-luciferase report assays assessed the relationship between USP46 and SP1. Results: USP46 and SP1 were upregulated in serum from MI patients and they had a positive correlation. OGD/R stimulation suppressed cardiomyocyte viability and proliferation, as well as induced cardiomyocyte inflammation, oxidative stress (OxS) injury, apoptosis, and ferroptosis, but these effects were impaired by USP46 or SP1 knockdown. SP1 could enhance the transcription of USP46, and USP46 overexpression reversed SP1 silencing-mediated effects on OGD/R-induced cardiomyocytes. SP1 mediated the AMPK signaling via USP46 . Conclusion: SP1 mediated OGD/R-induced cardiomyocyte inflammation, OxS injury, apoptosis, and ferroptosis by inactivating the AMPK signaling via enhancing the transcription of USP46.

IL-37 ameliorates myocardial fibrosis by regulating mtDNA-enriched vesicle release in diabetic cardiomyopathy mice

BackgroundDiabetic cardiomyopathy (DCM), a serious complication of diabetes, leads to structural and functional abnormalities of the heart and ultimately evolves to heart failure. IL-37 exerts a substantial influence on the regulation of inflammation and metabolism. Whether IL-37 is involved in DCM is unknown.MethodsThe plasma samples were collected from healthy controls, diabetic patients and DCM patients, and the level of IL-37 and its relationship with heart function were observed. The changes in cardiac function, myocardial fibrosis and mitochondrial injury in DCM mice with or without IL-37 intervention were investigated in vivo. By an in vitro co-culture approach involving HG challenge of cardiomyocytes and fibroblasts, the interaction carried out by cardiomyocytes on fibroblast profibrotic activation was studied. Finally, the possible interactive mediator between cardiomyocytes and fibroblasts was explored, and the intervention role of IL-37 and its relevant molecular mechanisms.ResultsWe showed that the level of plasma IL-37 in DCM patients was upregulated compared to that in healthy controls and diabetic patients. Both recombinant IL-37 administration or inducing IL-37 expression alleviated cardiac dysfunction and myocardial fibrosis in DCM mice. Mechanically, hyperglycemia impaired mitochondria through SIRT1/AMPK/PGC1α signaling, resulting in significant cardiomyocyte apoptosis and the release of extracellular vesicles containing mtDNA. Fibroblasts then engulfed these mtDNA-enriched vesicles, thereby activating TLR9 signaling and the cGAS-STING pathway to initiate pro-fibrotic process and adverse remodeling. However, the presence of IL-37 ameliorated mitochondrial injury by preserving the activity of SIRT1-AMPK-PGC1α axis, resulting in a reduction in release of mtDNA-enriched vesicle and ultimately attenuating the progression of DCM.ConclusionsCollectively, our study demonstrates a protective role of IL-37 in DCM, offering a promising therapeutic agent for this disease.Graphical abstractHyperglycemia aggravates mitochondrial injury through SIRT1/AMPK/PGC1α signaling, resulting in significant cardiomyocyte apoptosis and the release of extracellular vesicles containing mtDNA in DCM mice. Fibroblasts then engulf these mtDNA-enriched vesicles, activating TLR9 signaling and the cGAS-STING pathway to initiate profibrotic process and adverse remodeling. However, both exogenous and endogenous IL-37 ameliorate mitochondrial injury by preserving the activity of SIRT1-AMPK-PGC1α axis, and reducing the release of mtDNA-enriched vesicles, which attenuates the progression of DCM

Cardiac-specific PFKFB3 overexpression prevents diabetic cardiomyopathy via enhancing OPA1 stabilization mediated by K6-linked ubiquitination

Diabetic cardiomyopathy (DCM) is a prevalent complication of type 2 diabetes (T2D). 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3) is a glycolysis regulator. However, the potential effects of PFKFB3 in the DCM remain unclear. In comparison to db/m mice, PFKFB3 levels decreased in the hearts of db/db mice. Cardiac-specific PFKFB3 overexpression inhibited myocardial oxidative stress and cardiomyocyte apoptosis, suppressed mitochondrial fragmentation, and partly restored mitochondrial function in db/db mice. Moreover, PFKFB3 overexpression stimulated glycolysis. Interestingly, based on the inhibition of glycolysis, PFKFB3 overexpression still suppressed oxidative stress and apoptosis of cardiomyocytes in vitro, which indicated that PFKFB3 overexpression could alleviate DCM independent of glycolysis. Using mass spectrometry combined with co-immunoprecipitation, we identified optic atrophy 1 (OPA1) interacting with PFKFB3. In db/db mice, the knockdown of OPA1 receded the effects of PFKFB3 overexpression in alleviating cardiac remodeling and dysfunction. Mechanistically, PFKFB3 stabilized OPA1 expression by promoting E3 ligase NEDD4L-mediated atypical K6-linked polyubiquitination and thus prevented the degradation of OPA1 by the proteasomal pathway. Our study indicates that PFKFB3/OPA1 could be potential therapeutic targets for DCM.Graphical

Shexiang tongxin dropping pill alleviates myocardial injury induced by coronary microembolization by down-regulating APOC1 to inhibit STAT3 signaling pathway.

This study determines to validate the mechanism of Shexiang Tongxin dropping pill (STDP) in attenuating coronary microembolization (CME) induced myocardial injury. CME rat models were established and underwent corresponding treating. Gene chip analysis was performed in rat myocardial tissues for GO and KEGG enrichment analysis. The differentially expressed genes were detected by qRT-PCR. H&E staining and ELISA were used for pathological analysis and detection of troponin (cTnI) and Creatine Kinase Isoenzyme (CK-MB). Lipopolysaccharide (LPS) treated primary cardiomyocytes were used to mimic inflammatory in vitro models. Cell viability and apoptosis of cardiomyocytes were determined by MTT and flow cytometry. The expressions of inflammatory cytokines, apoptotic proteins and proteins related to the STAT3 signal pathway were detected by western blot. APOC1 mRNA expression was detected by qRT-PCR. Immunofluorescence (IF) was used for subcellular localization of p-STAT3 and the binding of APOC1 with STAT3 was verified using Co-IP. STDP can attenuate myocardial injury in CME rat models, and lead to decreased expression of APOC1 and suppressed STAT3 signal pathway. In vitro models found STDP can suppress the cell viability and cell apoptosis of primary cardiomyocytes, in addition to suppressing the secretions of IL-6, IL-1β and TNF-α, while the protective effect of STDP can be reversed by overexpression of APOC1. Co-IP found that APOC1 can bind STAT3 directly. APOC1 can increase p-STAT3 expression in the nucleus to activate the STAT3 signal pathway. STDP can suppress APOC1 and STAT3 signal pathway to inhibit inflammation and cell apoptosis of cardiomyocytes. APOC1 may be one of the key regulatory factors in CME-induced myocardial injury.

Mitochondria transplantation alleviates cardiomyocytes apoptosis through inhibiting AMPKα-mTOR mediated excessive autophagy.

The disruption of mitochondria homeostasis can impair the contractile function of cardiomyocytes, leading to cardiac dysfunction and an increased risk of heart failure. This study introduces a pioneering therapeutic strategy employing mitochondria derived from human umbilical cord mesenchymal stem cells (hu-MSC) (MSC-Mito) for heart failure treatment. Initially, we isolated MSC-Mito, confirming their functionality. Subsequently, we monitored the process of single mitochondria transplantation into recipient cells and observed a time-dependent uptake of mitochondria invivo. Evidence of human-specific mitochondrial DNA (mtDNA) in murine cardiomyocytes was observed after MSC-Mito transplantation. Employing a doxorubicin (DOX)-induced heart failure model, we demonstrated that MSC-Mito transplantation could safeguard cardiac function and avert cardiomyocyte apoptosis, indicating metabolic compatibility between hu-MSC-derived mitochondria and recipient mitochondria. Finally, through RNA sequencing and validation experiments, we discovered that MSC-Mito transplantation potentially exerted cardioprotection by reinstating ATP production and curtailing AMPKα-mTOR-mediated excessive autophagy.

Tibetan-Origin Edible Chinese Herbal Prescription C18 Protects H9C2 Cardiomyocytes from Cobalt Chloride-induced Hypoxia Injury through the PI3K/AKT Signaling Pathway

Background Altitude sickness is often prone to occur during tourism or work in high-altitude areas. In China, traditional Tibetan medicines have a long history of preventing or treating altitude sickness, especially altitude hypoxia, which may lead to myocardial cell apoptosis and myocardial hypoxia-reoxygenation injury. Purpose This study investigated the effect of a Tibetan-origin edible Chinese herbal prescription (named C18) on protecting H9C2 cardiomyocytes from cobalt chloride-induced hypoxia injury and its potential mechanism. Materials and Methods In this study, a hypoxic injury model of H9C2 cardiomyocytes induced by cobalt chloride was established first. Then the cell viability, relevant antioxidant indicators malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and protein expression (hypoxia-inducible factor 1 alpha (HIF-1α), phosphoinositide 3-kinase (PI3K), phosphorylated protein kinase B (p-AKT)) were measured after pretreatment with or without C18. At last, the specific PI3K/AKT inhibitor LY294002 was applied to verify the antihypoxia signaling pathway. Results C18 could significantly promote normal H9C2 cardiomyocyte proliferation and inhibit apoptosis of hypoxic H9C2 cardiomyocytes, reduce the release of lactate dehydrogenase and MDA, and increase the levels of SOD and GSH-Px antioxidant enzymes. In addition, C18 could significantly downregulate the expression of HIF-1α protein and upregulate the expression of intracellular p-AKT. Moreover, these effects of C18 can be blocked by the specific PI3K/AKT inhibitor LY294002. Conclusion C18 protects H9C2 cardiomyocytes from cobalt chloride-induced hypoxia injury through the PI3K/AKT signaling pathway.