Platycodin D Ameliorates Type 2 Diabetes-Induced Myocardial Injury by Activating the AMPK Signaling Pathway

The current study aimed to assess the effectiveness of pharmacological intervention with Platycodin D (PD), a critically active compound isolated from the roots of Platycodon grandiflorum, in mitigating cardiotoxicity in a murine model of type 2 diabetes-induced cardiac injury and in H9c2 cells in vitro. Following oral administration for 4 weeks, PD (2.5 mg/kg) significantly suppressed the elevation of fasting blood glucose (FBG) levels, improved dyslipidemia, and effectively inhibited the rise of the cardiac injury markers creatine kinase isoenzyme MB (CK-MB) and cardiac troponin T (cTnT). PD treatment could ameliorate energy metabolism disorders induced by impaired glucose uptake by activating AMPK protein expression in the DCM mouse model, thereby promoting the GLUT4 transporter and further activating autophagy-related proteins. Furthermore, in vitro experiments demonstrated that PD exerted a concentration-dependent increase in cell viability while also inhibiting palmitic acid and glucose (HG-PA)-stimulated H9c2 cytotoxicity and activating AMPK protein expression. Notably, the AMPK activator AICAR (1 mM) was observed to upregulate the expression of AMPK in H9c2 cells after high-glucose and -fat exposure. Meanwhile, we used AMPK inhibitor Compound C (20 μM) to investigate the effect of PD activation of AMPK on cells. In addition, the molecular docking approach was employed to dock PD with AMPK, revealing a binding energy of -8.2 kcal/mol and indicating a tight interaction between the components and the target. PD could reduce the expression of autophagy-related protein p62, reduce the accumulation of autophagy products, promote the flow of autophagy, and improve myocardial cell injury. In conclusion, it has been demonstrated that PD effectively inhibits cardiac injury-induced type 2 diabetes in mice and enhances energy metabolism in HG-PA-stimulated H9c2 cells by activating the AMPK signaling pathway. These findings collectively unveil the potential cardioprotective effects of PD via modulation of the AMPK signaling pathway.

Effects of different cryopreservation parameters on the differences between trypan blue and fluorescent SYTO 13/GelRed assays

Post-thaw cell viability assessment is very important in cryopreservation because it is the main assessment method used to optimize the cryopreservation protocols for each cell type; hence, having standardized accurate, quick, and reliable assays for post-thaw cell viability measurements is of utmost importance. The trypan blue exclusion assay and nucleic-acid-binding fluorescence-based assays are two different methods for cell viability assessment. Both assays identify cells with damaged membranes by whether they let a compound enter the cell. In this study, these two assays are compared in the context of cryopreservation and the impacts of important cryopreservation parameters on the differences in measurements are investigated. H9c2 myoblasts were cryopreserved with different freezing protocols. Cell membrane integrities were measured immediately after thaw as well as after cryoprotectant removal by a hemocytometer-based trypan blue dye exclusion assay and a dual fluorometric SYTO 13/GelRed assay; and the results were compared. This study quantifies how i) the absence or presence of different cryoprotectants, ii) different cell-cryoprotectant incubation conditions, and iii) the presence or removal of cryoprotectants after thaw affect the differences between these two viability assays.

Astaxanthin protects against pirarubicin-induced H9c2 cardiomyocytes by adjusting microRNA-494-3p-mediated MDM4/p53 signalling pathway

PURPOSE

Pirarubicin (THP) is an antitumour drug widely used in clinical practice, but its cardiotoxicity limits its application. THP cardiotoxicity must be treated as soon as possible. There is an urgent need to find drugs that alleviate THP cardiotoxicity. The purpose of this study was to investigate the effects and mechanisms of Astaxanthin (AST) on THP-induced cardiomyocytes.

METHODS

Rat cardiomyocytes H9c2 were induced with THP. The effects of AST on THP-induced H9c2 and its mechanism were investigated by CCK8, reactive oxygen species assay, tunnel assay, flow cytometry, RT-qPCR, and Western blot.

RESULTS

AST increased cell viability, inhibited apoptosis and accelerated cell cycle progression, reduced oxidative damage and inflammatory response in THP-induced H9c2; down-regulated miR-494-3p expression, promoted MDM4 expression, inhibited p53 activation, and suppressed apoptosis-related protein expression. Overexpression of MiR-494-3p reversed the above effects of AST.

CONCLUSIONS

AST can inhibit H9c2 apoptosis induced by THP and attenuate H9c2 damage by THP, which may be achieved by downregulating miR-494-3p, upregulating MDM4, and inhibiting p53.

Zinc Overload Induces Damage to H9c2 Cardiomyocyte Through Mitochondrial Dysfunction and ROS-Mediated Mitophagy

Zinc homeostasis is essential for maintaining redox balance, cell proliferation, and apoptosis. However, excessive zinc exposure is toxic and leads to mitochondrial dysfunction. In this study, we established a zinc overload model by treating rat cardiomyocyte H9c2 cells with Zn2+ at different concentrations. Our results showed that zinc overload increased LDH and reactive oxygen species (ROS) levels, leading to cell death, mitochondrial membrane potential decrease and impaired mitochondrial function and dynamics. Furthermore, zinc overload activated the PINK1/Parkin signaling pathway and induced mitochondrial autophagy via ROS, while NAC inhibited mitophagy and weakened the activation of PINK1/Parkin pathway, thereby preserving mitochondrial biogenesis. In addition, our data also showed that Mfn2 deletion increased ROS production and exacerbated cytotoxicity induced by zinc overload. Our results therefore suggest that Zn2+-induced ROS generation causes mitochondrial autophagy and mitochondrial dysfunction, damaging H9c2 cardiomyocytes. Additionally, Mfn2 may play a key role in zinc ion-mediated endoplasmic reticulum and mitochondrial interactions. Our results provide a new perspective on zinc-induced toxicology.

Coupling of static ultramicromagnetic field with elastic micropillar-structured substrate for cell response

Micropillars have emerged as promising tools for a wide range of biological applications, while the influence of magnetic fields on cell behavior regulation has been increasingly recognized. However, the combined effect of micropillars and magnetic fields on cell behaviors remains poorly understood. In this study, we investigated the responses of H9c2 cells to ultramicromagnetic micropillar arrays using NdFeB as the tuned magnetic particles. We conducted a comparative analysis between PDMS micropillars and NdFeB/PDMS micropillars to assess their impact on cell function. Our results revealed that H9c2 cells exhibited significantly enhanced proliferation and notable cytoskeletal rearrangements on the ultramicromagnetic micropillars, surpassing the effects observed with pure PDMS micropillars. Immunostaining further indicated that cells cultured on ultramicromagnetic micropillars displayed heightened contractility compared to those on PDMS micropillars. Remarkably, the ultramicromagnetic micropillars also demonstrated the ability to decrease reactive oxygen species (ROS) levels, thereby preventing F-actin degeneration. Consequently, this study introduces ultramicromagnetic micropillars as a novel tool for the regulation and detection of cell behaviors, thus paving the way for advanced investigations in tissue engineering, single-cell analysis, and the development of flexible sensors for cellular-level studies.

Peptide Characterization of Bovine Myocardium Hydrolysates and Its Ameliorative Effects on Doxorubicin-Induced Myocardial Injury in H9c2 Cells and in Mice

The prevalence and mortality of heart disease have a persistent existence, and it is important to develop active substances with cardioprotective properties. It has been reported that peptides from animal heart hydrolysates possess cardioprotective activity, but those mechanisms and the sequence of peptides are still unrevealed. In the present study, the extracts of bovine myocardium were prepared by enzymatic hydrolysis (BHH-A) and water extraction (BHH-W). The cardioprotective function of peptides was verified in the DOX-induced H9c2 cells and myocardial injury mice. The mass spectrometry was used to contrast the differences of active ingredients between BHH-W and BHH-A. Results suggested that both BHH-A and BHH-W could increase the activity of antioxidant enzymes in cardiomyocytes and reduce the inflammatory level and apoptosis of myocardial cells. The improvement effects of BHH-A on myocardial injury in mice were better than those of BHH-W. The analysis of peptide composition demonstrated that the contents with N-segment hydrophobic amino acids were higher in the peptides identified in BHH-A. Hence, BHH-A could be used as a potential active substance to improve DOX-induced myocardial injury by reducing oxidative damage, inflammation, and cardiomyocyte apoptosis, and its activity may be related to the richness of small molecular peptides and hydrophobic amino acids.

Three novel dalbergiphenol hybrids from the heartwood of Dalbergia cochinchinensis

A novel discovery of two hybrid benzodioxepin-dalbergiphenol epimers, named cochindalbergiphenols A-B (1-2), and a benzofuran-dalbergiphenol hybrid, named cochindalbergiphenol C (3), were isolated and identified from the heartwood of Dalbergia cochinchinensis. The structures of all the isolated compounds were identified through NMR and HRESIMS techniques, while the absolute configurations were determined by comparing the experimental and calculated ECD spectra. Compounds 1-3 exhibited potential protective effects against hypoxia/reoxygenation (H/R) induced injury in H9c2 cells.

Therapeutic potentials of terbium hydroxide nanorods for amelioration of hypoxia-reperfusion injury in cardiomyocytes

Myocardial hypoxia reperfusion (H/R) injury is the paradoxical exacerbation of myocardial damage, caused by the sudden restoration of blood flow to hypoxia affected myocardium. It is a critical contributor of acute myocardial infarction, which can lead to cardiac failure. Despite the current pharmacological advancements, clinical translation of cardioprotective therapies have proven challenging. As a result, researchers are looking for alternative approaches to counter the disease. In this regard, nanotechnology, with its versatile applications in biology and medicine, can confer broad prospects for treatment of myocardial H/R injury. Herein, we attempted to explore whether a well-established pro-angiogenic nanoparticle, terbium hydroxide nanorods (THNR) can ameliorate myocardial H/R injury. For this study, in vitro H/R-injury model was established in rat cardiomyocytes (H9c2 cells). Our investigations demonstrated that THNR enhance cardiomyocyte survival against H/R-induced cell death. This pro-survival effect of THNR is associated with reduction of oxidative stress, lipid peroxidation, calcium overload, restoration of cytoskeletal integrity and mitochondrial membrane potential as well as augmentation of cellular anti-oxidant enzymes such as glutathione-s-transferase (GST) and superoxide dismutase (SOD) to counter H/R injury. Molecular analysis revealed that the above observations are traceable to the predominant activation of PI3K-AKT-mTOR and ERK-MEK signalling pathways by THNR. Concurrently, THNR also exhibit apoptosis inhibitory effects mainly by suppression of pro-apoptotic proteins like Cytochrome C, Caspase 3, Bax and p53 with simultaneous restoration of anti-apoptotic protein, Bcl-2 and Survivin. Thus, considering the above attributes, we firmly believe that THNR have the potential to be developed as an alternative approach for amelioration of H/R injury in cardiomyocytes.

Upregulation of miR-21-5p rescues the inhibition of cardiomyocyte proliferation induced by high glucose through negative regulation of Rhob

Increasing evidence shows that maternal hyperglycemia inhibits cardiomyocyte (CM) proliferation and promotes cell apoptosis during fetal heart development, which leads to cardiac dysplasia. Accumulating evidence suggests that the overexpression of miR-21 in CMs has a protective role in cardiac function. Therefore, we investigated whether miR-21 can rescue CM injury caused by high glucose. First, we performed biological function analysis of miR-21-5p overexpression in H9c2 cells treated with high glucose. We found that the proliferation of H9c2 cells treated with high glucose decreased significantly and was rescued after overexpression of miR-21-5p. CCK-8 and EdU incorporation assays were performed to assess cell proliferation. The cell proliferation of the miR-21-5p mimic transfection group was improved compared with that of the NC mimic group (*p < 0.05, miR-21-5p mimics vs. NC mimics) when the proliferation of H9c2 cells was reduced by high glucose (****p < 0.0001, high glucose (HG) vs. normal glucose (NG)). Then, we verified the targeted and negative regulation of miR-21-5p on Rhob using a dual-luciferase activity assay and RT-qPCR, respectively. We further demonstrated that miR-21-5p regulates Rhob to rescue the inhibition of CM proliferation induced by high glucose. The CCK-8 results showed that the cell proliferation of the siRNA-Rhob group was higher than that of the NC mimic group (***p < 0.001) and that of the cotransfection group with Up-Rhob plasmids and miR-21-5p mimics was lower than that of the miR-21-5p mimic group (*p < 0.05). Conclusion: Overexpression of miR-21-5p rescues the inhibition of high glucose-induced CM proliferation through regulation of Rhob.

TRPV1 Channels Are New Players in the Reticulum-Mitochondria Ca2+ Coupling in a Rat Cardiomyoblast Cell Line

The Ca2+ release in microdomains formed by intercompartmental contacts, such as mitochondria-associated endoplasmic reticulum membranes (MAMs), encodes a signal that contributes to Ca2+ homeostasis and cell fate control. However, the composition and function of MAMs remain to be fully defined. Here, we focused on the transient receptor potential vanilloid 1 (TRPV1), a Ca2+-permeable ion channel and a polymodal nociceptor. We found TRPV1 channels in the reticular membrane, including some at MAMs, in a rat cardiomyoblast cell line (SV40-transformed H9c2) by Western blotting, immunostaining, cell fractionation, and proximity ligation assay. We used chemical and genetic probes to perform Ca2+ imaging in four cellular compartments: the endoplasmic reticulum (ER), cytoplasm, mitochondrial matrix, and mitochondrial surface. Our results showed that the ER Ca2+ released through TRPV1 channels is detected at the mitochondrial outer membrane and transferred to the mitochondria. Finally, we observed that prolonged TRPV1 modulation for 30 min alters the intracellular Ca2+ equilibrium and influences the MAM structure or the hypoxia/reoxygenation-induced cell death. Thus, our study provides the first evidence that TRPV1 channels contribute to MAM Ca2+ exchanges.

mTOR Inhibitors Modulate the Physical Properties of 3D Spheroids Derived from H9c2 Cells

To establish an appropriate in vitro model for the local environment of cardiomyocytes, three-dimensional (3D) spheroids derived from H9c2 cardiomyoblasts were prepared, and their morphological, biophysical phase contrast and biochemical characteristics were evaluated. The 3D H9c2 spheroids were successfully obtained, the sizes of the spheroids decreased, and they became stiffer during 3-4 days. In contrast to the cell multiplication that occurs in conventional 2D planar cell cultures, the 3D H9c2 spheroids developed into a more mature form without any cell multiplication being detected. qPCR analyses of the 3D H9c2 spheroids indicated that the production of collagen4 (COL4) and fibronectin (FN), connexin43 (CX43), β-catenin, N-cadherin, STAT3, and HIF1 molecules had increased and that the production of COL6 and α-smooth muscle actin (α-SMA) molecules had decreased as compared to 2D cultured cells. In addition, treatment with rapamycin (Rapa), an mTOR complex (mTORC) 1 inhibitor, and Torin 1, an mTORC1/2 inhibitor, resulted in significantly decreased cell densities of the 2D cultured H9c2 cells, but the size and stiffness of the H9c2 cells within the 3D spheroids were reduced with the gene expressions of several of the above several factors being reduced. The metabolic responses to mTOR modulators were also different between the 2D and 3D cultures. These results suggest that as unique aspects of the local environments of the 3D spheroids, the spontaneous expression of GJ-related molecules and hypoxia within the core may be associated with their maturation, suggesting that this may become a useful in vitro model that replicates the local environment of cardiomyocytes.

MicroRNA-186-5p inhibits H9c2 cells apoptosis induced by oxygen-glucose deprivation by targeting ERK1/2

Background

Serum miR-186-5p levels are increased in acute myocardial infarction (AMI) patients and might contribute to assessing the prognosis of AMI patients. In this study, we further investigated the underlying molecular mechanism of miR-186-5p that participated in the pathological processes of myocardial ischemia.

Methods

The AMI models of rats and oxygen-glucose deprivation (OGD) models of H9c2 cells were established. Bioinformatics databases, luciferase reporting, and western blotting assays were performed to identify the regulatory target of miR-186-5p. Transfection and functional experiments were conducted to further define the possible molecular mechanism of miR-186-5p during the process of glucose deficiency and hypoxia.

Results

The level of miR-186-5p was found to significantly decrease in H9c2 cells after OGD treatment, while it increased in the culture medium from OGD-treated H9c2 cells. Using bioinformatics databases, luciferase reporting, and western blotting assays, we identified that ERK1/2 might serve as the negative regulatory target of miR-186-5p. Combined with further transfection experiments, we indicated that miR-186-5p might inhibit the expression and activation of ERK1/2. This finding was also reflected in the reduction of their downstream cleaved caspase-3. Through functional experiments, we revealed that miR-186-5p might inhibit apoptosis and promote proliferation in OGD-treated H9c2 cells.

Conclusions

We demonstrated that miR-186-5p might suppress OGD-induced apoptosis in H9c2 cells by targeting the ERK1/2 pathway.

Biological effects of sub-lethal doses of glyphosate and AMPA on cardiac myoblasts

Introduction: Glyphosate is the active compound of different non-selective herbicides, being the most used agriculture pesticide worldwide. Glyphosate and AMPA (one of its main metabolites) are common pollutants of water, soil, and food sources such as crops. They can be detected in biological samples from both exposed workers and general population. Despite glyphosate acts as inhibitor of the shikimate pathway, present only in plants and some microorganisms, its safety in mammals is still debated. Acute glyphosate intoxications are correlated to cardiovascular/neuronal damages, but little is known about the effects of the chronic exposure. Methods: We evaluated the direct biological effects of different concentrations of pure glyphosate/AMPA on a rat-derived cell line of cardiomyoblasts (H9c2) in acute (1-2 h) or sub-chronic (24-48 h) settings. We analyzed cell viability/morphology, ROS production and mitochondrial dynamics. Results: Acute exposure to high doses (above 10 mM) of glyphosate and AMPA triggers immediate cytotoxic effects: reduction in cell viability, increased ROS production, morphological alterations and mitochondrial function. When exposed to lower glyphosate concentrations (1 μM-1 mM), H9c2 cells showed only a slight variation in cell viability and ROS production, while mitochondrial dynamic was unvaried. Moreover, the phenotype was completely restored after 48 h of treatment. Surprisingly, the sub-chronic (48 h) treatment with low concentrations (1 μM-1 mM) of AMPA led to a late cytotoxic response, reflected in a reduction in H9c2 viability. Conclusion: The comprehension of the extent of human exposure to these molecules remains pivotal to have a better critical view of the available data.

LPS preconditioning of MSC-CM improves protection against hypoxia/reoxygenation-induced damage in H9c2 cells partly via HMGB1/Bach1 signalling

Mesenchymal stem cell-derived conditioned medium (MSC-CM) improves cardiac function after myocardial infarction; however, this cardioprotective effect is moderate and transient. Lipopolysaccharide (LPS) pretreatment partially improves MSC-CM-mediated cardioprotective effects owing to the presence of paracrine factors. However, the mechanism underlying these improved effects remains unknown. To study the effect of LPS-pretreated MSC-CM on hypoxia/reoxygenation (H/R)-induced injury, MSCs were treated with or without LPS (400 ng/mL) for 48 h, and the supernatant was collected (MSC-CM). Subsequently, H9c2 cells were co-cultured with Nor-CM (CM derived from LPS-untreated MSCs) and LPS-CM (CM derived from LPS-pretreated MSCs) for 24 h and subjected to H/R. MSC-CM inhibited the progression of H/R-induced injury in H9c2 cells, and this protective effect was enhanced via LPS pretreatment as evidenced by the improved apoptosis assessment index (i.e. caspase-3 and B-cell lymphoma-2 [Bcl-2] expression) and decreased levels of lactic dehydrogenase (LDH) and cardiac troponin (cTn). In addition, the results of haematoxylin-eosin staining (H&E), transmission electron microscopy (TEM) and TdT-mediated dUTP nick-end labelling (TUNEL) validated that MSC-CM inhibited H/R-induced injury in H9c2 cardiomyocytes. LPS pretreatment downregulated the expression of high mobility group box-1 (HMGB1) and BTB and CNC homology-1 (Bach1) proteins in MSCs but upregulated the expression of vascular endothelial growth factor (VEGF), hepatocyte growth factor (HGF) and insulin-like growth factor (IGF). HMGB1 knockdown (MSC/siHMGB1-CM) significantly decreased the expression of Bach1 and increased the expression of VEGF, HGF and IGF. Bach1 knockdown (MSC/siBach1-CM) did not alter the production of HMGB1 but increased the expression of VEGF and IGF. LPS pretreatment did not alter the expression of the paracrine factors VEGF and HGF in the MSC/siHMGB1 group but increased their expression in the MSC/siBach1 group. The myocyte anti-apoptotic effects of MSCs/siBach1-CM were similar to those of untreated MSCs, which were not enhanced by LPS. LPS-pretreated MSC-CM protects H9c2 cells against H/R-induced injury partly through the HMGB1/Bach1 signalling pathway.

Natural remedies medicine derived from flaxseed (secoisolariciresinol diglucoside, lignans, and α-linolenic acid) improve network targeting efficiency of diabetic heart conditions based on computational chemistry techniques and pharmacophore modeling

Cytokine storms lead to cardiovascular diseases (CVDs). Natural herbal compounds are considered the primary source of active agents with the potential to prevent or treat inflammatory-related pathologies such as CVD and diabetes. Flaxseed contains phytochemicals, including secoisolariciresinol diglucoside (SDG), α-linolenic acid (ALA), and lignans, termed "SAL." Hence, we evaluated the effect of the SAL on the H9c2 cardiac cells in hyperlipidemic and hyperglycemic conditions. Here, candidate hub genes, TNF-α, IL6, SIRT1, NRF1, NPPA, and FGF7, were selected as effective genes in diabetic cardiovascular pathogenesis based on in-silico analysis and chemoinformatic. Myocardial infarction (MI) was induced using H9c2 cardiac cells in hyperlipidemic and hyperglycemic conditions. Real-time qPCR was conducted to assess the expression level of hub genes. This study indicated that SAL compounds bound to the Il-6, SIRT1, and TNF-α active sites as druggable candidate proteins based on the chemoinformatics analysis. This study displayed that the TNF-α, IL6, SIRT1, NRF1, NPPA, and FGF7 network dysfunction in MI models were ameliorated by SAL consumption. Furthermore, SAL compounds improved the function and myogenesis of H9c2 cells in hyperlipidemic and hyperglycemic conditions. Our data suggested that phytochemicals obtained from flaxseed might have proposed potential complementary treatment or preventive strategies for MI. PRACTICAL APPLICATIONS: Phytochemicals obtained from flaxseed (SAL) could reverse diabetic heart dysfunction hallmarks and provide new potential treatment approaches in cardiovascular therapy. SAL could be considered complementary and alternative medicines for treating various disorders/diseases singly or synchronizing with prescription drugs.

Anti-ischemic effect of Tamarindus indica L. seed extract against myocardial hypoxic injury

Background: Ischemic heart disease is a leading cause of death in patients with cardiovascular disease. Natural products containing high antioxidant activity have been used as an alternative therapy to improve the living conditions of patients. In this study, we examine the protective effect of tamarind seed (TS) on myocardial hypoxic injury. Methods: The hypoxia model was mimicked by mineral oil overlayed on H9c2 cardiomyoblasts for 4 h. TS extract was pretreated and administered during the hypoxic condition. Radical scavenging activity of TS extract was measured and exhibited very potent antioxidant activities on 2,2-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid (ABTS) assays. Results: TS extract at a concentration of 10 µg/ml significantly reversed the effect of hypoxia-induced cell death and intracellular reactive oxygen species (ROS) production. We also observed hypoxia-induced over-expression of both inflammatory cytokine mRNA and activation of cellular apoptosis. Pretreatment of TS extract significantly reduced hypoxia-induced HIF-1a and pro-inflammatory cytokine production, IL-1b and IL-6. The Western blot analysis for apoptotic regulatory molecules, caspase 3, caspase 8 and Bax proteins, also showed hypoxia injury reversal by TS extract treatment. Conclusions: The results suggest that the anti-ischemic effect of TS extract protects against hypoxia-induced injury and has potential to be an effective alternative therapy for ischemic heart disease and oxidative-damage related disease.

Potential cardiotoxicity induced by Euodiae Fructus: In vivo and in vitro experiments and untargeted metabolomics research

Background: Euodiae Fructus, a well-known herbal medicine, is widely used in Asia and has also gained in popularity in Western countries over the last decades. It has known side effects, which have been observed in clinical settings, but few studies have reported on its cardiotoxicity. Methods: In the present study, experiments using techniques of untargeted metabolomics clarify the hazardous effects of Euodiae Fructus on cardiac function and metabolism in rats in situations of overdosage and unsuitable syndrome differentiation. In vitro assays are conducted to observe the toxic effects of evodiamine and rutaecarpine, two main chemical constituents of Euodiae Fructus, in H9c2 and neonatal rat cardiomyocytes (NRCMs), with their signaling mechanisms analyzed accordingly. Results: The cardiac cytotoxicity of evodiamine and rutaecarpine in in vivo experiments is associated with remarkable alterations in lactate dehydrogenase, creatine kinase, and mitochondrial membrane potential; also with increased intensity of calcium fluorescence, decreased protein expression of the cGMP-PKG pathway in H9c2 cells, and frequency of spontaneous beat in NRCMs. Additionally, the results in rats with Yin deficiency receiving a high-dosage of Euodiae Fructus suggest obvious cardiac physiological dysfunction, abnormal electrocardiogram, pathological injuries, and decreased expression of PKG protein. At the level of endogenous metabolites, the cardiac side effects of overdose and irrational usage of Euodiae Fructus relate to 34 differential metabolites and 10 metabolic pathways involving among others, the purine metabolism, the glycerophospholipid metabolism, the glycerolipid metabolism, and the sphingolipid metabolism. Conclusion: These findings shed new light on the cardiotoxicity induced by Euodiae Fructus, which might be associated with overdose and unsuitable syndrome differentiation, that comes from modulating the cGMP-PKG pathway and disturbing the metabolic pathways of purine, lipid, and amino acid. Continuing research is needed to ensure pharmacovigilance for the safe administration of Chinese herbs in the future.

Overexpression of miR-383-3p protects cardiomyocytes against hypoxia/reoxygenation injury via regulating PTEN/PI3K/AKT signal pathway

MicroRNAs are widely reported as biomarkers and therapeutic targets in cardiovascular diseases. This study is aimed to expound on the regulatory responsibility of miR-383-3p in H/R-induced injury of H9c2 cells. In this study, H9c2 cells were administrated with H/R. MiR-383-3p expression was measured using qRT-PCR. ELISA was used to determine lactate dehydrogenase (LDH), superoxide dismutase (SOD), and malondialdehyde (MDA) levels. Reactive oxygen species (ROS) were detected with 2,7-Dichlorodihydrofluorescein diacetate probe. 3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-di- phenytetrazoliumromide, flow cytometry, and TUNEL experiments were conducted to measure cell viability and apoptosis. Cleaved caspase-3, caspase-3, Bax, Bcl-2, PTEN, PI3K, p-PI3K, Akt, p-AKT expression levels were examined by Western blot. Cleaved caspase-3 expression was also measured by immunofluorescence staining. Dual-luciferase reporter gene assay was applied to validate the binding sites in miR-383-3p and the 3'UTR of PTEN. We reported that, miR-383-3p expression in H9c2 cells treated with H/R was remarkably decreased. MiR-383-3p overexpression ameliorated oxidative stress and apoptosis and promoted cell viability in H9c2 cells treated with H/R, while miR-383-3p inhibitor showed the reverse effects. PTEN was identified as a target gene of miR-383-3p. Additionally, enhancement of PTEN expression abolished the influences of miR-383-3p on H9c2 cells. MiR-383-3p mimics could significantly decrease PTEN expression in H9c2 cells while increasing p-PI3K expression and p-AKT expression, while the miR-383-3p inhibitors showed the opposed effects. In conclusion, miR-383-3p protected H9c2 cells from H/R-induced injury via regulating PTEN/PI3K/AKT signal pathway.

Qishen Yiqi dropping pills improve isoproterenol-induced cardiomyocyte hypertrophy by regulating X-inactive specific transcript (XIST) expression in rats

Background

This study aimed to explore the potential mechanism of Qishen Yiqi dropping pills (QYDPs) in the treatment of chronic heart failure (CHF) by regulating the expression of lncRNAs during CHF.

Methods

Differences in the expression of the long non-coding RNA (lncRNA), X-inactive specific transcript (XIST), in an isoproterenol (ISO)-induced cardiomyocyte hypertrophy model treated with QYDPs was analyzed by reverse transcription quantitative polymerase chain reaction (RT-qPCR). A cell counting kit-8 (CCK8) assay, flow cytometry (FCM), and enzyme linked immunosorbent assay (ELISA) were used to analyze the protective effects of QYDPs on the proliferation rate, apoptosis, myocardial enzyme, oxidative stress, and inflammation of cardiomyocytes, as well as the molecular mechanism of XIST.

Results

Our results showed that in the ISO-induced cardiomyocyte hypertrophy model, XIST expression and apoptosis were increased, the cell proliferation rate was decreased, and myocardial enzyme levels increased [i.e., increased lactate dehydrogenase (LDH) and creatine kinase (CK) levels]. Furthermore, cellular oxidative stress [i.e., increased malondialdehyde (MDA) levels and decreased superoxide dismutase (SOD) levels] and inflammatory response [i.e., increased interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α protein secretion] were also promoted. QYDP treatment effectively mitigated the effects of ISO induction. Subsequently, we found that suppressing XIST expression reversed the effect of ISO induction, whereas overexpression (ov) of XIST enhanced the effect of ISO induction. Finally, this study confirmed that QYDP treatment improved the ISO-induced decrease in proliferation, apoptosis, and promotion of oxidative stress and inflammatory response in cardiomyocytes, whereas ov of XIST partially negated the effect of QYDPs.

Conclusions

QYDPs protected H9c2 cells from ISO-induced damage by downregulating XIST expression.

Blueberry extract attenuates norepinephrine-induced oxidative stress and apoptosis in H9c2 cardiac cells

Enhanced sympathetic system activation mediated by norepinephrine (NE) contributes to adverse cardiac remodeling leading to oxidative stress and cell death, progressing to heart failure. Natural antioxidants may help maintain redox balance, attenuating NE-mediated cardiac cell damage. In the present study, we evaluated the effect of a blueberry extract (BBE) on H9c2 cardiac cells exposed to NE on cell death, oxidative stress status and its major signaling pathways. H9c2 cells were pre-incubated with 50 μg/ml of BBE for 4 h and maintained in the presence of 100 μM NE for 24 h. NE exposure resulted in increased caspase 3/7 activity. This was associated with reduced protein expression of antioxidants catalase, superoxide dismutase and glutathione peroxidase and increase in 4-hydroxynonenal adduct formation. NE led to increased activity of Protein kinase B (Akt), Forkhead box O3a and AMP-activated protein kinase alpha and decreased activity of Signal transducer and activator of transcription 3. BBE prevented caspases activation and abrogated NE-induced increase in oxidative stress, as well as attenuated the increase in Akt. Based on these findings, it is concluded that BBE promoted cardioprotection of H9c2 cells in an in vitro model of NE-induced oxidative damage, suggesting a cardioprotective role for BBE in response to NE exposure.

Effect of Ginsenoside Rb2 on a Myocardial Cell Model of Coronary Heart Disease through Nrf2/HO-1 Signaling Pathway

The ginsenoside Rbs are the primary active compounds of Panax ginseng and ginsenoside Rb2 is a renowned component among the Rbs. This study aimed to investigate the potential effects of ginsenoside Rb2 on coronary heart disease (CHD). H9c2 cells were exposed to H₂O₂ to establish CHD model in vitro. Gene expression was determined by quantitative realtime PCR (qPCR) and Western blot. Cellular functions were detected by Cell Counting Kit-8 (CCK-8), 5-ethynyl-2'-deoxyuridine (EdU), flow cytometry, and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL) assays. We found that Ginsenoside Rb2 promoted cell proliferation while suppressed oxidative stress and apoptosis of H9c2 cells induced by H₂O₂ exposure. Mechanistically, Ginsenodise Rb2 involves in the regulation of nuclear factor, erythroid 2 like 2 (Nrf2)/heme oxygenase (HO)-1 signaling pathway. Inactivation of Nrf2/HO-1 signaling pathway reversed the effects of ginsenoside Rb2 on H9c2 cells. Taken together, ginsenoside Rb2 exhibited a cardioprotective effect in vitro. The underlying mechanism of ginsenoside Rb2 in H9c2 cells could be standardized to Nrf2/HO-1 signaling pathway, inhibiting cell apoptosis and regaining cell proliferation. The present study has proposed a novel mechanism of ginsenoside Rb2 in the cardioprotective effect.

Curcumin Conjugated Gold Nanoclusters as Perspective Therapeutics for Diabetic Cardiomyopathy

Accumulation of lipids in the myocardium contributes to the development of cardiac dysfunctions and various chronic diseases, such as diabetic cardiomyopathy (DCM). Curcumin (Cur) can relieve lipid accumulation problems, but its efficiency is limited by poor water solubility and biocompatibility. Herein, gold nanoclusters (AuNCs) were used to improve the efficiency of Cur, and the conjugates Curcumin-AuNCs (AuCur) were developed. In the treatment of high-fat-induced myocardial cell damage, we found that AuCur could effectively reduce intracellular lipid accumulation, the increase of reactive oxygen species (ROS), the increase of mitochondrial division, and the increase of apoptosis compared with Cur. AuCur decreased the expression of the peroxisome proliferator-activated receptors-α subtype (PPARα), and the therapeutic effect of AuCur was canceled when the expression of PPARα was enhanced. For the above reasons, AuCur treated the toxic effect of high lipid on cardiomyocytes by regulating PPARα, providing a new idea and method for the treatment of DCM.

Astragaloside IV protects cardiomyocytes against hypoxia injury via HIF-1α and the JAK2/STAT3 pathway

Background

Hypoxia is an important cause of myocardial injury due to the heart’s high susceptibility to hypoxia. Astragaloside IV (AS-IV) is the main component of Astragalus membranaceus and could exert cardiac protective role. Here, the effect of AS-IV on hypoxia-injured H9c2 cardiomyocytes was elucidated.

Methods

First, H9c2 cells were exposed to hypoxia and/or AS-IV treatment. Cell apoptosis, death, and viability as well as hypoxia-inducible factor 1α (HIF-1α) expression and apoptotic proteins were analyzed. Next, transfection of si-HIF-1α into H9c2 cells was carried out to test whether upregulation and stabilization of HIF-1α influences the effect of AS-IV on hypoxia-treated H9c2 cells. Furthermore, the regulatory role of Janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) signaling on HIF-1α levels was examined.

Results

Hypoxia suppressed viability and promoted the apoptosis and death of H9c2 cells. AS-IV eliminated hypoxia-induced H9c2 injury. Moreover, HIF-1α signaling was further activated and stabilized by AS-IV in hypoxia-challenged H9c2 cells. Downregulation of HIF-1α suppressed the function of AS-IV in hypoxia-challenged H9c2 cells. AS-IV promoted JAK2/STAT3 signaling in hypoxia-induced injury. The beneficial functions of AS-IV in hypoxia-exposed H9c2 cells were linked to HIF-1α upregulation and JAK2/STAT3 signaling activation.

Conclusions

AS-IV relieved H9c2 cardiomyocyte injury after hypoxia, possibly by activating JAK2/STAT3-mediated HIF-1α signaling.

Oxidative stress pathogenically remodels the cardiac myocyte cytoskeleton via structural alterations to the microtubule lattice

In the failing heart, the cardiac myocyte microtubule network is remodeled, which contributes to cellular contractile failure and patient death. However, the origins of this deleterious cytoskeletal reorganization are unknown. We now find that oxidative stress, a condition characteristic of heart failure, leads to cysteine oxidation of microtubules. Our electron and fluorescence microscopy experiments revealed regions of structural damage within the microtubule lattice that occurred at locations of oxidized tubulin. The incorporation of GTP-tubulin into these damaged, oxidized regions led to stabilized "hot spots" within the microtubule lattice, which suppressed the shortening of dynamic microtubules. Thus, oxidative stress may act inside of cardiac myocytes to facilitate a pathogenic shift from a sparse microtubule network into a dense, aligned network. Our results demonstrate how a disease condition characterized by oxidative stress can trigger a molecular oxidation event, which likely contributes to a toxic cellular-scale transformation of the cardiac myocyte microtubule network.

Amnion membrane proteins attenuate LPS-induced inflammation and apoptosis by inhibiting TLR4/NF-κB pathway and repressing MicroRNA-155 in rat H9c2 cells

OBJECTIVE

Amnion membrane (AM) has been popular for the treatment of inflammatory disorders due to its cell repairing properties. This current study aims to find the underlying mechanisms of amnion membrane proteins (AMPs) against the pro-inflammatory miRNA, miR-155, miR-146, and anti-apoptotic microRNA, miR-21, in LPS-treated H9c2 cells.

METHODS

Cell viability and apoptosis were determined by MTT assay and annexin V/PI staining. The production of the cytokines, TNF-α and IL-6 were evaluated by using qPCR and Enzyme-linked immunosorbent assay (ELISA), respectively. In addition, the expression of miRNAs was quantified by qPCR, and also the protein level of TLR4 and NF-kβ was determined with western blotting.

RESULTS

We found that AMPs ameliorated LPS-induced reduction of cell viability and augment apoptosis in H9c2 cells. AMPs efficiently inhibited cytokine expression (IL-6 and TNF-α) and activity of TLR4/NF-κB pathway in LPS-treated H9c2 cells. Correspondingly, in parallel with the suppression of pro-inflammatory cytokines and apoptosis, AMPs mitigated pro-inflammatory miRNA, miR-155 expression, while, the expression of miR-155 was found to be increased in LPS-treated H9c2 cells. Also, AMPs activated miR-146 expression in H9c2 cells under LPS treatment. Additionally, the elevated expression of miR-21 provoked by LPS was further enhanced by AMPs.

CONCLUSIONS

In conclusion, AMPs could alleviate LPS-induced cardiomyocytes cells injury via up-regulation of miR-21, miR-146, and suppression of TLR4/NF-κB pathway, which plays a key role in the down-regulation of LPS-mediated miR-155 and inflammatory cytokine expression.

Maduramicin arrests myocardial cells at G0/G1 phase of the cell cycle through inhibiting AKT-Cyclin D1 signaling

Maduramicin, a polyether ionophore antibiotic used as an anticoccidial feed additive in poultry, is toxic to animals and humans and can cause heart failure. The present study was initiated to explore the underlying mechanism of toxicity in H9c2 myocardial cells. We observed using cell imaging and counting methods that maduramicin inhibited cell growth in a concentration-dependent manner. Furthermore, MTT assays showed that maduramicin inhibited cell proliferation in a concentration- and time-dependent manner, and was also confirmed by the finding that maduramicin time dependently blocked the incorporation of BrdU into DNA in H9c2 myocardial cells. Further studies revealed that maduramicin induced accumulation of the cells at G₀/G₁ phase of the cell cycle and concurrently, there was down regulation of expression of Cyclin D1. In addition, exposure to maduramicin pruned phosphorylation of AKT at both T308 and S473 sites. Finally, we found that pre-treatment of H9c2 myocardial cells with AKT activator SC79, attenuated the inhibitory effects of maduramicin on Cyclin D1 expression and cell proliferation. Collectively, our results suggest that maduramicin-suppressed AKT-Cyclin D1 signaling which results in G₀/G₁ phase cell cycle arrest, leading to the inhibition of myocardial cell proliferation.

Production of TRPM4 knockout cell line using rat cardiomyocyte H9c2

The method presented in this article are related to the research article entitled as “Role of the TRPM4 channel in mitochondrial function, calcium release, and ROS generation in oxidative stress" [1]. TRPM4, a non-selective monovalent cation channel, is not only involved in the generation of the action potential in cardiomyocytes, but also thought to be a key molecule in the development of the ischemia–reperfusion injury of the brain and the heart [2], [3], [4], [5]. However, existing pharmacological inhibitors for the TRPM4 channel have problems of non-specificity [6]. This article describes methods used for targeted genomic deletion in the rat cardiomyocyte H9c2 using the CRISPR-Cas9 genome editing system in order to suppress TRPM4 protein expression. Confocal microscopy, flow cytometry, Sanger sequencing, and western blotting are performed to confirm vector transfection and the subsequent knockout of the TRPM4 protein.•

These data provide information on the comprehensive analyses for knocking out the rat TRPM4 channel using CRISPR/Cas9. The analyses include confocal microscopy, flow cytometry, Sanger sequencing, and western blotting.

•

This dataset will benefit biological and medical researchers studying the function of TRPM4-expressing cells including neurons, cardiomyocytes, and vascular endothelial cells. It is also useful to study the involvement of the TRPM4 channel in pathological processes such as cardiac arrhythmia and ischemia–reperfusion injury.

•

The dataset can be used to guide the experiment of knocking out the TRPM4 gene and its subsequent application to the study of disease process caused by the gene.

MicroRNA-145-5p inhibits hypoxia/reoxygenation-induced apoptosis in H9c2 cardiomyocytes by targeting ROCK1

There is increasing evidence that microRNAs (miRs) play critical roles in the pathological and physiological processes associated with myocardial ischemia reperfusion (I/R). miR-145 has been extensively studied in the cardiovascular system; however, the role of miR-145 in myocardial I/R remains unclear. Therefore, the present study aimed to investigate the role and mechanism of miR-145-5p in myocardial I/R by establishing a hypoxia/reoxygenation (H/R) model using H9c2 cardiomyocytes. The expression of miR-145-5p was regulated by transfection and the potential target of miR-145-5p was identified. In addition, apoptosis of the cardiomyocytes was evaluated using flow cytometry and the detection of cleaved caspase-3 by western blotting. The results revealed that miR-145-5p expression was decreased while cell apoptosis and Rho-associated coiled-coil-containing kinase 1 (ROCK1) expression were increased in H/R-stimulated H9c2 cardiomyocytes. The upregulation of miR-145-5p reduced apoptosis and the expression of ROCK1 in H/R-stimulated H9c2 cardiomyocytes. Furthermore, the overexpression of ROCK1 significantly attenuated the miR-145-5p-induced reduction of apoptosis following H/R. In conclusion, the present study indicates that the overexpression of miR-145-5p inhibits H/R-induced cardiomyocyte apoptosis by targeting ROCK1.

Acute promyelocytic leukemia drug - arsenic trioxide in the presence of eugenol shows differential action on leukemia cells (HL-60) and cardiomyocytes (H9c2) - inference from NMR study

The increased concern of cardiovascular dysfunction by cancer therapeutics has led to more effective treatment strategies. Arsenic trioxide (As₂O₃) is a potential chemotherapeutic agent for acute promyelocytic leukemia (APL), but the effectiveness is affected by potential cardiotoxicity. Researchers have been trying to find out novel modalities to manage the adverse effects of As₂O₃. In our study, the antioxidant molecule eugenol showed protective action against the destructive impact of As₂O₃ on cardiomyocytes (H9c2) without compromising the anti-cancer property As₂O₃ on leukemia cells (HL-60). We have studied the interaction between arsenic and eugenol in physiological and acidic pH to understand the molecular mechanism of differential action of As₂O₃ in the presence of eugenol using NMR spectroscopy. The study observed that at physiological pH, arsenic and eugenol interact to form an inactive product, positively affecting H9c2 cardiomyocytes. Still, there is no such interaction in acidic pH evidenced by the useful anti-cancer property of As₂O₃. The result concludes that the antioxidant molecule eugenol is an efficient protective agent against the adverse effect of As₂O₃ on cardiomyocytes.

MiR-489 aggravates H2O2-induced apoptosis of cardiomyocytes via inhibiting IGF1

Myocardial infarction (MI) is a major type of cardiovascular disorder worldwide. In the present study, we established a new microRNA (miRNA)–mRNA cross-talk network by integrating data obtained from The National Center for Biotechnology Information Gene Expression Omnibus (NCBI GEO). In addition, functional assays, including Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway and Gene Ontology (GO) analyses, were conducted using the Database for Annotation, Visualization, and Integration Discovery (DAVID). In our study, we generated a new differentially expressed miRNA (DEmiRNA)-differentially expressed gene (DEG) cross-talk network of MI composed of three miRNA (miR-489, miR-375, and miR-142-3p) nodes and 163 mRNA nodes. In vitro experiments demonstrated that miR-489 expression was increased in H₂O₂-treated H9c2 cardiomyocytes in vitro, mimicking myocardial injury. We observed that down-regulation of miR-489 reduced H₂O₂-induced apoptosis, while overexpression of miR-489 had the opposite effects, as revealed by flow cytometry and Western blot analyses. Furthermore, we confirmed the relationship between miR-489 and IGF1 through double luciferase reporter gene assays, which partly explains the antiapoptotic mechanism of miR-489. In conclusion, the experimental results of the present study could provide important clues for investigating the mechanism of MI.

Cardiac Protective Effect of Kirenol against Doxorubicin-Induced Cardiac Hypertrophy in H9c2 Cells through Nrf2 Signaling via PI3K/AKT Pathways

Kirenol (KRL) is a biologically active substance extracted from Herba Siegesbeckiae. This natural type of diterpenoid has been widely adopted for its important anti-inflammatory and anti-rheumatic properties. Despite several studies claiming the benefits of KRL, its cardiac effects have not yet been clarified. Cardiotoxicity remains a key concern associated with the long-term administration of doxorubicin (DOX). The generation of reactive oxygen species (ROS) causes oxidative stress, significantly contributing to DOX-induced cardiac damage. The purpose of the current study is to investigate the cardio-protective effects of KRL against apoptosis in H9c2 cells induced by DOX. The analysis of cellular apoptosis was performed using the terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) staining assay and measuring the modulation in the expression levels of proteins involved in apoptosis and Nrf2 signaling, the oxidative stress markers. Furthermore, Western blotting was used to determine cell survival. KRL treatment, with Nrf2 upregulation and activation, accompanied by activation of PI3K/AKT, could prevent the administration of DOX to induce cardiac oxidative stress, remodeling, and other effects. Additionally, the diterpenoid enhanced the activation of Bcl2 and Bcl-xL, while suppressing apoptosis marker proteins. As a result, KRL is considered a potential agent against hypertrophy resulting from cardiac deterioration. The study results show that KRL not only activates the IGF-IR-dependent p-PI3K/p-AKT and Nrf2 signaling pathway, but also suppresses caspase-dependent apoptosis.

Identification of miR-145 as a regulator of the cardiomyocyte inflammatory response and oxidative stress under hyperglycemia

The current study aimed to explore the effects of microRNA (miR)-145 on the inflammatory response and oxidative stress (OS) in high glucose (HG)-induced cardiomyocytes, as well as the specific mechanism underlying this action. H9c2 cells were treated with 33 mmol/l glucose (HG group) or cotreated with 24.5 mmol/l mannitol and 5.5 mmol/l glucose (hypertonic group), and the expression levels of miR-145 and ADP ribosylation factor 6 (ARF6) were detected. The cells were transfected with pcDNA3.1-ARF6, miR-145 mimics or corresponding negative controls prior to the assessment of cell survival rate. Levels of lactate dehydrogenase (LDH), reactive oxygen species (ROS) and malondialdehyde (MDA), as well as the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), and the levels of IL-6, TNF-α and monocyte chemoattractant protein-1 (MCP-1) were subsequently determined. The apoptotic rate of H9c2 cells was examined by flow cytometry. The interaction between miR-145-ARF6 was predicted and confirmed by luciferase reporter assays. In the HG group, miR-145 expression was significantly decreased and ARF6 expression significantly increased compared with controls. Furthermore, the levels of inflammatory factors (IL-6, TNF-α and MCP-1), LDH, ROS and MDA were significantly elevated in the HG group compared with controls. Significantly decreased SOD, CAT and GPx activities and significantly increased numbers of apoptotic cells were observed in the HG group compared with controls. The cells transfected with miR-145 mimics exhibited significantly decreased LDH, ROS and MDA levels, significantly increased antioxidant enzyme activities and significantly decreased apoptotic rates compared with controls, while the opposite results were observed in cells transfected with pcDNA3.1-ARF6. Moreover, co-transfection with miR-145 mimics and pcDNA3.1-ARF6 exacerbated the inflammatory response and OS injury in HG-induced cardiomyocytes compared with cells transfected with miR-145 mimics alone. Furthermore, miR-145 negatively targeted ARF6. miR-145 attenuated the HG-induced inflammatory response and OS injury in cardiomyocytes by negatively regulating ARF6, which may contribute to providing a theoretical basis for the treatment of diabetic cardiomyopathy.

PTEN mediates serum deprivation-induced cytotoxicity in H9c2 cells via the PI3K/AKT signaling pathway

The pathogenesis of acute myocardial infarction (AMI) is associated with cardiomyocyte necrosis and apoptosis. Numerous studies have determined the regulatory effects of Phosphatase and tensin homolog (PTEN) cell proliferation and apoptosis in other cell types. However, the potential role of PTEN in cardiomyocyte is unclear. In this study, we used H9c2 cells cultured under serum deprivation to simulate the apoptosis process of myocardial infarction. Small interference RNA (siRNA) of PTEN was used to knock down the expression of PTEN. Cell viability was determined by CCK-8. Cell proliferation was examined by Edu staining, and the protein expression was analyzed by Western blot. We also evaluated the generation of ROS, the degree of DNA damage, and cell apoptosis using immunofluorescence assay. As a result, we observed that serum deprivation in H9c2 cells increased PTEN expression. Functionally, the PTEN knockdown experiment using siRNA inhibited serum deprivation-induced cell apoptosis, ROS production, and DNA damage, whereas increased cell proliferation. All these effects could be reversed by phosphatidylinositol 3-kinase (PI3K) inhibitor, which indicated the PI3K/protein kinase B (AKT) might be the critical component of the PTEN effects during serum deficiency. In conclusion, our study indicated the role of the PTEN/PI3K/AKT pathway in serum deprivation-induced cytotoxicity in H9c2 cells.

Swietenine extracted from Swietenia relieves myocardial hypertrophy induced by isoprenaline in mice

As a traditional plant medicine in tropical areas, Swietenia macrophylla seeds are usually applied for some chronic diseases, including hypertension, diabetes, and so on. Few studies have been carried out to identify the effective elements in seed extract and their indications. In this study, we first investigated the functions of the swietenine, an extract from S. macrophylla seeds, using a model of myocardial hypertrophy induced by isoprenaline (ISO). At cellular level, H9c2 cell hypertrophy was also established through the treatment with ISO. The cardiac pathological remodeling was evaluated by echocardiography and histological analysis. Western blot and RT-qPCR were used to detect the expression of possible hypertrophy-promoting genes. Here, our results indicated that swietenine remarkably attenuated ISO-induced myocardial hypertrophy in vivo and in vitro. Moreover, Akt phosphorylation, ANP and BNP mRNA expression were efficiently decreased. Based on these findings, we concluded that swietenine might be a promising anti-hypertrophic agent against cardiac hypertrophy.

Dendrobium candidum aqueous extract attenuates isoproterenol-induced cardiac hypertrophy through the ERK signalling pathway

CONTEXT

The pharmacological functions of Dendrobium candidum Wall. ex Lindl. (Orchidaceae) in cardiac hypertrophy remains unclear.

OBJECTIVE

To evaluate whether D. candidum aqueous extract (DCAE) can attenuate experimental cardiac hypertrophy.

MATERIALS AND METHODS

Cardiac hypertrophy in SD rats was induced by subcutaneously injection of isoproterenol (2 mg/kg), once a day for ten days. Rats were gavaged with DCAE (0.13 and 0.78 g/kg) daily for one month. At the end of treatment, measurement of left ventricular systolic pressure (LVSP), heart-to-body weight ratio (HW/BW), left ventricular/tibia length (LV/TL), atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP) levels, haematoxylin-eosin staining, and Masson's trichrome staining were conducted. In cultured H9c2 cells, DCAE (2 mg/mL) and U0126 (10 μM) were added 2 h before the isoproterenol (10 μM) stimulus. Phalloidin staining was used to evaluate cellular hypertrophy. The mRNA expression of ANP and BNP was measured by qRT-PCR. The expression of p-ERK was determined by immunoblotting.

RESULTS

DCAE treatment significantly reduced the following indicators in vivo: (1) the LVSP (16%); (2) HW/BW (13%); (3) LV/TL (6%); (4) ANP (39%); (5) BNP (32%). In cultured H9c2 cells, phalloidin staining showed that DCAE relieved cellular hypertrophy (53% reduction). Furthermore, immunoblotting showed that DCAE can significantly inhibit p-ERK protein expression in vivo and in vitro (39% and 27% reduction, respectively).

DISCUSSION AND CONCLUSIONS

DCAE prevents cardiac hypertrophy via ERK signalling pathway and has the potential for treatment of cardiac hypertrophy.

Effect of phenylacetamide isolated from lepidium apetalum on myocardial injury in spontaneously hypertensive rats and its possible mechanism

Context: In the antihypertensive study of phenylacetamide (PA) on spontaneously hypertensive rats (SHR), it was occasionally found that PA prevents myocardial injury.Objective: Clarify the protective mechanism of PA on myocardial injury in SHR rats.Materials and methods: In vivo, SHR rats were treated with or without PA (15, 30, 45 mg/kg) for 3 weeks (12 per group). In vitro, H9c2 cells were treated with PA (1, 5, 10 μM) for 24 h, and then stimulated with H₂O₂ (300 μM) for 4 h. Molecular mechanisms were explored through cardiac pathology, cardiac function and biochemical markers.Results: In vivo, PA (15, 30, 45 mg/kg) reduced CVF from 14.8 ± 1.62 to 9.94 ± 1.56, 8.6 ± 1.33, 8.14 ± 1.45%; increased the LVEF relative level from 0.8 ± 0.06 to 0.83 ± 0.04, 0.86 ± 0.05, 0.9 ± 0.04. All three doses can improve the cardiac pathological structure and function (LVEDD, LVESD, LVFS, heart index, NT-proBNP, CKMB, SBP); however, 45 mg/kg works best. But different doses show different molecular mechanisms. PA (15 mg/kg) improves RAAS system (REN, ACE), inflammation (ET-1, IL-1β) and MAPK pathway (p-ERK/ERK, p-JNK/JNK) better. PA (45 mg/kg) improves oxidative stress (SOD, NOX1) and TGF-β pathway (Smad3) better. In vitro, PA improved cell viability, oxidative stress (SOD, NOX1) and Smad3 protein expression.Discussion and conclusions: PA regulates different mechanisms at different concentrations to improve myocardial injury, and high dose is the best. This experiment provides a theoretical basis for the development of new clinical drugs for cardiovascular disease.

Upregulation of miRNA-23a-3p rescues high glucose-induced cell apoptosis and proliferation inhibition in cardiomyocytes

Maternal hyperglycemia potentially inhibits the development of the fetal heart by suppressing cardiomyocyte proliferation and promoting apoptosis. Different studies have indicated that miRNAs are key regulators of cardiomyocyte proliferation, differentiation, and apoptosis and play a protective role in a variety of cardiovascular diseases. However, the biological function of miRNA-23a in hyperglycemia-related cardiomyocyte injury is not fully understood. The present study investigated the effect of miRNA-23a-3p on cell proliferation and apoptosis in a myocardial injury model induced by high glucose. H9c2 cardiomyocytes were exposed to high glucose to establish an in vitro myocardial injury model and then transfected with miRNA-23a-3p mimics. After miRNA-23a-3p transfection, lens-free microscopy was used to dynamically monitor cell numbers and confluence and calculate the cell cycle duration. CCK-8 and EdU incorporation assays were performed to detect cell proliferation. Flow cytometry was used to measured cell apoptosis. Upregulation of miRNA-23a-3p significantly alleviated high glucose-induced cell apoptosis and cell proliferation inhibition (p < 0.01 and p < 0.0001, respectively). The cell cycle of the miRNA-23a-3p mimics group was significantly shorter than that of the negative control group (p < 0.01). The expression of cell cycle–activating and apoptosis inhibition-associated factors Ccna2, Ccne1, and Bcl-2 was downregulated by high glucose and upregulated by miRNA-23a-3p overexpression in high glucose-injured H9c2 cells. miRNA-23a-3p mimics transfection before high glucose treatment had a significantly greater benefit than transfection after high glucose treatment (p < 0.0001), and the rescue effect of miRNA-23a-3p increased as the concentration increased. This study suggests that miRNA-23a-3p exerted a dose- and time-dependent protective effect on high glucose-induced H9c2 cardiomyocyte injury.

TRPM7 silencing attenuates Mg2+ influx in cardiac myoblasts, H9c2 cells

TRPM7, a member of the melastatin subfamily of transient receptor potential channels, is suggested to be a potential candidate for a physiological Mg2+ channel. However, there is no direct evidence of Mg2+ permeation through endogenous TRPM7. To determine the physiological roles of TRPM7 in intracellular Mg2+ homeostasis, we measured the cytoplasmic free Mg2+ concentration ([Mg2+]i) in TRPM7-silenced H9c2 cells. [Mg2+]i was measured in a cluster of 8-10 cells using the fluorescent indicator, furaptra. TRPM7 silencing did not change [Mg2+]i in Ca2+-free Tyrode's solution containing 1 mM Mg2+. Increasing the extracellular Mg2+ to 92.5 mM raised [Mg2+]i in control cells (1.56 ± 0.19 mM) at 30 min, while this effect was significantly attenuated in TRPM7-silenced cells (1.12 ± 0.07 mM). The Mg2+ efflux driven by Na+ gradient was unaffected by TRPM7 silencing. These results suggest that TRPM7 regulates the rate of Mg2+ influx in H9c2 cells, although cytoplasmic Mg2+ homeostasis at basal conditions is unaffected by TRPM7 silencing.

Axenfeld-Rieger syndrome-associated mutants of the transcription factor FOXC1 abnormally regulate NKX2-5 in model zebrafish embryos

FOXC1 is a member of the forkhead family of transcription factors, and whose function is poorly understood. A variety of FOXC1 mutants have been identified in patients diagnosed with the autosomal dominant disease Axenfeld-Rieger syndrome, which is mainly characterized by abnormal development of the eyes, particularly those who also have accompanying congenital heart defects (CHD). However, the role of FOXC1 in CHD, and how these mutations might impact FOXC1 function, remains elusive. Our previous work provided one clue to possible function, demonstrating that zebrafish foxc1a, an orthologue of human FOXC1 essential for heart development, directly regulates the expression of nkx2.5, encoding a transcriptional regulator of cardiac progenitor cells. Abnormal expression of Nkx2-5 leads to CHD in mice and is also associated with CHD patients. Whether this link extends to the human system, however, requires investigation. In this study, we demonstrate that FOXC1 does regulate human NKX2-5 expression in a dose-dependent manner via direct binding to its proximal promoter. A comparison of FOXC1 mutant function in the rat cardiac cell line H9c2 and zebrafish embryos suggested that the zebrafish embryos might serve as a more representative model system than the H9c2 cells. Finally, we noted that three of the Axenfeld-Rieger syndrome FOXC1 mutations tested increased, whereas a fourth repressed the expression of NKX2-5 These results imply that mutant FOXC1s might play etiological roles in CHD by abnormally regulating NKX2-5 in the patients. And zebrafish embryos can serve as a useful in vivo platform for rapidly evaluating disease-causing roles of mutated genes.

Cardioprotection by AN-7, a prodrug of the histone deacetylase inhibitor butyric acid: Selective activity in hypoxic cardiomyocytes and cardiofibroblasts

The anticancer prodrug butyroyloxymethyl diethylphosphate (AN-7), upon metabolic hydrolysis, releases the histone deacetylase inhibitor butyric acid and imparts histone hyperacetylation. We have shown previously that AN-7 increases doxorubicin-induced cancer cell death and reduces doxorubicin toxicity and hypoxic damage to the heart and cardiomyocytes. The cardiofibroblasts remain unprotected against both insults. Herein we examined the selective effect of AN-7 on hypoxic cardiomyocytes and cardiofibroblasts and investigated mechanisms underlying the cell specific response. Hypoxic cardiomyocytes and cardiofibroblasts or H₂O₂-treated H9c2 cardiomyoblasts, were treated with AN-7 and cell damage and death were evaluated as well as cell signaling pathways and the expression levels of heme oxygenase-1 (HO-1). AN-7 diminished hypoxia-induced mitochondrial damage and cell death in hypoxic cardiomyocytes and reduced hydrogen peroxide damage in H9c2 cells while increasing cell injury and death in hypoxic cardiofibroblasts. In the cell line, AN-7 induced Akt and ERK survival pathway activation in a kinase-specific manner including phosphorylation of the respective downstream targets, GSK-3β and BAD. Hypoxic cardiomyocytes responded to AN-7 treatment by enhanced phosphorylation of Akt, ERK, GSK-3β and BAD and a significant 6-fold elevation in HO-1 levels. In hypoxic cardiofibroblasts, AN-7 did not activate Akt and ERK beyond the effect of hypoxia alone and induced a limited (~1.5-fold) increase in HO-1. The cell specific differences in kinase activation and in heme oxygenase-1 upregulation may explain, at least in part, the disparate outcome of AN-7 treatment in hypoxic cardiomyocytes and hypoxic cardiofibroblasts.

Epigallocatechin-3-gallate ameliorates LPS-induced inflammation by inhibiting the phosphorylation of Akt and ERK signaling molecules in rat H9c2 cells

The inflammatory response has been implicated in various cardiac and systemic diseases. Epigallocatechin-3-gallate (EGCG), the major polyphenol extracted from green tea, has various biological and pharmacological properties, such as anti-inflammation, anti-oxidative and anti-tumorigenesis. To some extent, the mechanism of EGCG in the inflammatory response that characterizes myocardial dysfunction is not fully understood. The present study aimed to investigate the inhibiting effect of EGCG on lipopolysaccharide (LPS)-induced inflammation in vitro. Treatment with LPS affected rat H9c2 cardiomyocytes and induced an inflammatory response. However, the LPS-induced effects were attenuated after treatment with EGCG. The present results demonstrated that EGCG treatment repressed several inflammatory mediators, such as vascular endothelial growth factor, chemokine ligand 5, chemokine ligand 2, intercellular adhesion molecule-1, matrix metalloproteinase-2, tumor necrosis factor-α and nitric oxide (induced by LPS), and the repressing effect of EGCG on inflammatory response was dose-dependent in the range of 6.25-100 µM. EGCG inhibited these marked inflammatory key signaling molecules by reducing the expression of phospho-nuclear factor-κB p65, -Akt, -ERK and -MAPK p38 while the total protein level of these signal proteins were not affected. In conclusion, the present findings suggested that EGCG possesses cardiomyocyte-protective action in reducing the LPS-induced inflammatory response due to the inhibition of the phosphorylation of Akt and ERK signaling molecules.

Elevated aldolase 1A, retrogene 1 expression induces cardiac apoptosis in rat experimental autoimmune myocarditis model

Acute myocarditis is an unpredictable heart disease that is caused by inflammation-associated cell death. Although viral infection and drug exposure are known to induce acute myocarditis, the molecular basis for its development remains undefined. Using proteomics and molecular analyses in myosin-induced rat experimental autoimmune myocarditis (EAM), we identified that elevated expression of aldolase 1A, retrogene 1 (Aldoart1) is critical to induce mitochondrial dysfunction and acute myocarditis development. Here, we demonstrate that cardiac cell death is associated with increased expressions of proapoptotic genes in addition to high levels of glucose, lactate, and triglyceride in metabolite profiling. The functional protein association network analysis also suggests that Aldoart1 upregulation correlates with high levels of dihydroxyacetone kinase and triglyceride. In H9c2 cardiac cells, lipopolysaccharides (LPS) or high glucose exposure significantly increases the cytochrome c release and the conversion of pro-caspase 3 into the cleaved form of caspase 3. We also found that LPS- or glucose-induced toxicities are almost completely reversed by siRNA-mediated knockdown of Aldoartl, which consequently increases cell viability. Together, our study strongly suggests that Aldoart1 may be involved in inducing mitochondrial apoptotic processes and can be a novel therapeutic target to prevent the onset of acute myocarditis or cardiac apoptosis.

Aconitine induces cardiotoxicity through regulation of calcium signaling pathway in zebrafish embryos and in H9c2 cells

Fuzi, the processed lateral roots of Aconitum carmichaelii Debx., is a traditional herbal medicine that is well known for its excellent pharmacological effects and acute toxicity. Aconitine is one of the diester-diterpene alkaloids and well-known for its arrhythmogenic effects. However, the effects of aconitine in zebrafish have rarely been studied. Therefore, we investigated the effects of aconitine on zebrafish embryos and H9c2 cells. Zebrafish embryos at 48 hours postfertilization were exposed to aconitine, and then, cardiac function and apoptosis were measured. Through transcriptomic analysis, the cardiotoxicity of aconitine in zebrafish embryos was involved in regulating Ca²⁺ signal pathways. A reverse transcription-polymerase chain reaction was performed to verify the expression of Ca²⁺ pathway-related genes after 12, 24, 36 and 48 hours of treatment. Meanwhile, intracellular Ca²⁺ concentrations and cell apoptosis were observed in H9c2 cells treated with half-maximal inhibitory concentration values of aconitine for 30 minutes. The protein levels of troponin T (TnT), caspase 3, Bcl-2 and Bax were detected by western blot analysis. In vivo, 2.0 and 8.0 μm aconitine decreased the heart rate and inhibited the contraction of ventricles and atria in a dose- and time-dependent manner. Furthermore, aconitine increased expression of cacna1c, RYR2, atp2a2b, Myh6, troponin C, p38, caspase 3, Bcl-2 and Bax for 12 hours. In vitro, 1.5 and 4.5 mm aconitine caused intracellular Ca²⁺ ion oscillation, increased rates of apoptosis, inhibited TnT and Bcl-2 protein expression, and promoted caspase 3 and Bax protein expression. These data confirmed that aconitine at various concentrations induced cardiac dysfunction and apoptosis were related to the Ca²⁺ signaling pathway.

Involvement of Yes-associated protein 1 (YAP1) in doxorubicin-induced cytotoxicity in H9c2 cardiac cells

Cardiac cell death is one of the major events implicated in doxorubicin-induced cardiotoxicity, which leads to heart failure. We recently reported that Yes-associated protein 1 (YAP1) regulates cell survival and apoptosis. However, it is unclear whether YAP1 regulates doxorubicin-induced cell death in cardiomyocytes. We investigated whether YAP1 is involved in doxorubicin-induced cell death using H9c2 cardiac cells and mouse heart. In an in vivo study, YAP1 protein expression was significantly decreased in hearts of doxorubicin-treated mice with increased caspase-3 activation. Doxorubicin also caused cell death by increasing caspase-3 activation in H9c2 cells. Doxorubicin reduced YAP1 protein expression and messenger RNA expression accompanied by increased phosphorylation of YAP1 at Ser127. Doxorubicin further increased cell death with increased caspase-3/7 activation in the absence of YAP1 when compared with doxorubicin or siYAP1 treatment alone. Overexpression of constitutively active YAP1 (YAP1-5SA) using an adenovirus gene transfer technique significantly reversed doxorubicin-induced cell death by decreasing caspase-3/7 activation in H9c2 cells. Akt, a potential prosurvival factor, decreased in doxorubicin- and YAP1 short interfering RNA (siRNA)-treated cells. Doxorubicin further significantly decreased Akt protein expression when YAP1 was silenced. Overexpression of YAP1 canceled decreased Akt protein expression induced by doxorubicin treatment in H9c2 cells. In conclusion, these results suggest that doxorubicin-induced cardiac cell death is mediated in part by down-regulation of YAP1 and YAP1-targeted gene, Akt. Modulating YAP1 and its related Hippo pathway on local cardiomyocytes may be a promising therapeutic approach for doxorubicin-induced cardiotoxicity.

Crocin protects cardiomyocytes against LPS-Induced inflammation

BACKGROUND

Sepsis causes organ dysfunctions via elevation of oxidative stress and inflammation. Lipopolysaccharide (LPS) is the major surface molecule of most gram-negative bacteria and routinely used as a sepsis model in investigation studies. Crocin is an active compound of saffron which has different pharmacological properties such as anti-oxidant and anti-inflammatory. In this research, the protective effect of crocin was evaluated against LPS-induced toxicity in the embryonic cardiomyocyte cell line (H9c2).

METHODS

The cells were pre-treated with different concentration of crocin (10, 20 and 40 μM) for 24 h, and then LPS was added (10 μg/ml) for another 24 h. Afterward, the percentage of cell viability and the levels of inflammatory cytokines (TNF-α, PGE2, IL-1β, and IL-6), gene expression levels (TNF-α, COX-2, IL-1β, IL-6, and iNOS), and the level of nitric oxide (NO) and thiol were measured.

RESULTS

Our results showed that LPS reduced cell viability, increased the levels of cytokines, gene-expression, nitric oxide, and thiol. Crocin attenuated the LPS-induced toxicity in H9c2 cells via reducing the levels of inflammatory factors (TNF-α, PGE2, IL-1β, and IL-6, p < 0.001), gene expression (TNF-α, COX-2, IL-1β, IL-6, and iNOS, p < 0.001), and NO (p < 0.001), whereas increased the level of thiol content (p < 0.001).

CONCLUSION

The observed results revealed that crocin has preventive effects on the LPS induced sepsis and its cardiac toxicity in-vitro model. Probably, these findings are related to anti-inflammatory and anti-oxidant properties of crocin. However, performing further animal studies are necessary to support the therapeutic effects of crocin in septic shock cardiac dysfunction.

2,3,5,4'-Tetrahydroxystilbene-2-O-β-d-glucoside eliminates ischemia/reperfusion injury-induced H9c2 cardiomyocytes apoptosis involving in Bcl-2, Bax, caspase-3, and Akt activation

OBJECTIVE

This study was designed to explore the protective effect of 2,3,5,4'-tetrahydroxystilbene-2-O-β-d-glucoside (TSG) against ischemia/reperfusion (I/R) injury-induced cardiomyocytes apoptosis.

METHODS

The H9c2 cell I/R injury model was induced by simultaneous shortage of nutrients and oxygen. TSG administration (0.10, 0.25, and 0.50 mM) was performed before and during I/R stimulation. Cell apoptosis was evaluated using terminal deoxynucleotidyl transferase dUTP nick end labeling assay. Expression of cell-related proteins was detected to assess the effect of TSG on cell apoptosis.

RESULTS

I/R injury induced significant cell apoptosis. Significantly decreased Bcl-2 and increased Bax, caspase-3, and p-Akt expression ( P < 0.01) was detected in the cell model of I/R injury. In contrast, TSG administration eliminated all the changes induced by I/R injury in a dose-dependent manner. Compared with the H9c2 cell model of I/R injury, the H9c2 cells treated with 0.50 mM TSG showed the lowest cell apoptosis percentage, the highest expression of Bcl-2, and the lowest expression of Bax, caspase-3, and p-Akt ( P < 0.01).

CONCLUSION

We confirmed that the protective effect of TSG against I/R injury-induced cell apoptosis in H9c2 in vitro was associated with the Bcl-2/Bax ratio, caspase-3, and Akt activation.

Tid1-S attenuates LPS-induced cardiac hypertrophy and apoptosis through ER-a mediated modulation of p-PI3K/p-Akt signaling cascade

Myocardial dysfunction is clinically relevant? repercussion that follows sepsis. Tid 1 protein has been implicated in many biological process. However, the role of Tid 1 in lipopolysaccharide (LPS)-induced cardiomyocyte hypertrophy and apoptosis remains elusive. In the current research endeavor, we have elucidated the role of Tid1-S on LPS-induced cardiac hypertrophy and apoptosis. Interestingly, we found that overexpression of Tid1-S suppressed TLR-4, NFATc3, and BNP protein expression which eventually led to inhibition of LPS-induced cardiac hypertrophy. Moreover, Tid1-S overexpression attenuated cellular apoptosis and activated survival proteins p-PI3K and p^ser473 Akt. Besides this, Tid1-S overexpression enhanced ER-a protein expression. Collectively, our data suggest that Tid1-S plausibly enhance ER-a protein and further activate p-PI3K and p ^ser473 Akt survival protein expression; which thereby led to attenuation of LPS-induced apoptosis in cardiomyoblast cells. Interestingly, our data suggest that Tid1-S is involved in attenuation of cardiomyoblast cells damages induced by LPS.

High glucose induced calcium overload via impairment of SERCA/PLN pathway and mitochondrial dysfunction leads to oxidative stress in H9c2 cells and amelioration with ferulic acid

Oxidative stress and associated complications are the major pathological concerns of diabetic cardiomyopathy (DC). We aim to elucidate the mechanisms by which high glucose (HG) induced alteration in calcium homeostasis and evaluation of the beneficial effect of two concentrations (10 and 25 μm) of ferulic acid (FA). HG was induced in H9c2 cardiomyoblast by treating with glucose (33 mm) for 48 h, and FA was co-treated. Intracellular calcium ([Ca²⁺ ]i) overload was found increased significantly with HG. For elucidation of mechanism, the SERCA pathway and mitochondrial integrity (transmembrane potential and permeability transition pore) were explored. Then, we assessed oxidative stress, and cell injury with brain natriuretic peptide (BNP), atrial natriuretic peptide (ANP), and lactate dehydrogenase (LDH) release. HG caused significant [Ca²⁺ ]i overload through downregulation of SERCA2/1, pPLN, and pPKA C-α; and upregulation of PLN and PKA C-α and alteration in the integrity of mitochondria with HG. The [Ca²⁺ ]i overload in turn caused oxidative stress via generation of reactive oxygen species, lipid peroxidation, and protein carbonylation. This resulted in cell injury which was evident with significant release of BNP, ANP, and LDH. FA co-treatment was effective to mitigate all pathological changes caused by HG. From the overall results, we conclude that [Ca²⁺ ]i overload via SERCA pathway and altered mitochondrial integrity is the main cause for oxidative stress during HG. Based on our result, we report that FA could be an attractive nutraceutical for DC.

Glucagon-like peptide-1 attenuates endoplasmic reticulum stress-induced apoptosis in H9c2 cardiomyocytes during hypoxia/reoxygenation through the GLP-1R/PI3K/Akt pathways

Endoplasmic reticulum (ER) stress-induced apoptosis is a major cause of myocardial ischemia/reperfusion (I/R) injury. Emerging evidence indicates that glucagon-like peptide-1 (GLP-1) has potential cardioprotective effects. However, the precise mechanisms underlying the involvement of GLP-1 in I/R injury remain largely unknown. In the present study, we aimed to determine whether GLP-1 attenuates hypoxia/reoxygenation (H/R) injury in cardiomyocytes and to further elucidate the underlying signaling pathway. The results indicate that GLP-1 reversed the increased apoptotic ratio, the increased lactate dehydrogenase (LDH) levels, the reduced cell viability, the increased Caspase-3 activity, and the increased Bax/Bcl-2 ratio caused by H/R. Importantly, GLP-1 significantly decreased the expression of H/R-induced ER stress proteins (GRP78, CHOP) and Caspase-12. In addition, we found that GLP-1 increased the expression of p-Akt in H9c2 cells with H/R injuries, and that the protective action of GLP-1 against H/R-induced injury was blocked by the GLP-1 receptor (GLP-1R) inhibitor Exendin9-39 and the PI3K inhibitor LY294002. Exendin9-39 and LY294002 also blocked the downregulation of ER stress protein expression by GLP-1, after H/R injury. Therefore, we have shown that GLP-1 exerts its cardioprotective effects by alleviating ER stress-induced apoptosis due to H/R injury and that these effects are most likely associated with the activation of GLP-1R/PI3K/Akt signaling pathway.

Sphingosine-1-phosphate attenuates hypoxia/reoxygenation-induced cardiomyocyte injury via a mitochondrial pathway

Our previous study showed that Sphingosine-1-phosphate (S1P) could protect cardiomyocytes against hypoxia/reoxygenation (H/R) injury via the JAK-STAT pathway and maintain normal myocardial mitochondria integrity in vivo. However, it is not known yet whether S1P can relieve mitochondrial dysfunction via the mitochondrial apoptotic pathway and its detailed mechanism remains to be investigated. The aim of this study was to demonstrate the mitochondrial protective effects of S1P in a cardiomyocyte H/R injury model. In the present study, we established a H/R model in H9c2 cells. Cell viability was determined by the MTT assay, and apoptosis was evaluated by annexin V-FITC/PI staining. Mitochondrial calcium ion concentration, mitochondrial membrane potential (ΔΨm), opening of the mitochondrial permeability transition pore (mPTP), and release of cytochrome C were detected by laser confocal microscopy. The results showed that S1P inhibited the decrease in cell viability induced by H/R injury and reduced apoptosis. Confocal microscopy showed that S1P prevented loss of ΔΨm, relieved mitochondrial calcium overload, and inhibited opening of the mPTP and release of cytochrome C. The STAT3 inhibitor STATTIC can reverse the antiapoptotic effects of S1P and block the effect of S1P on mitochondria. Taken together, our results indicate that S1P protects cardiomyocytes against H/R injury by relieving mitochondrial dysfunction via the STAT3 pathway.