AC16 Cells Research Articles

Circ_0068655 silencing ameliorates hypoxia-induced human cardiomyocyte injury by regulating apoptotic and inflammatory responses.

There is growing evidence suggesting that the dysregulation of circular RNAs (circRNAs) plays a significant role in various myocardial disorders, including myocardial ischemia (MI). This study aimed to explore the function of hsa_circ_0068655 (circ_0068655) in hypoxia-induced cardiomyocyte injury. Human AC16 cardiomyocyte cells were cultured under anaerobic condition to induce an in vitro model of MI. Cell apoptosis was assessed by Annexin V-fluorescein isothiocyanate staining and caspase-3 and caspase-9 activity assays. Cell proliferation was analyzed by 5-Ethynyl-2'-deoxyuridine (EdU) incorporation assay. Inflammation was evaluated by enzyme-linked immunosorbent assays. Circ_0068655, miR-370-3p and BCL-2-like 11 (BCL2L11) expression were detected by real-time quantitative polymerase chain reaction or western blotting. The target interactions among circ_0068655, miR-370-3p and BCL2L11 were predicted using bioinformatics tools and validated using dual-luciferase reporter assays and RNA immunoprecipitation assays. Hypoxia treatment led to upregulated expression of circ_0068655 and BCL2L11, and downregulated expression of miR-370-3p in AC16 cells. This treatment also resulted in reduced cell viability, increased apoptosis rate, elevated caspase-9/3 activities and cleavage, and enhanced production of tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-1β. Notably, knockdown of circ_0068655 alleviated these detrimental effects. In addition, circ_0068655 silencing-mediated effects were restored by decreasing miR-370-3p expression in hypoxia-treated AC16 cells. Moreover, ectopic BCL2L11 expression remitted the effects of miR-370-3p overexpression on hypoxia-treated AC16 cells. Mechanistically, circ_0068655 was found to act as a sponge for miR-370-3p, thereby regulating BCL2L11 expression. Circ_0068655 silencing ameliorated hypoxia-induced human cardiomyocyte injury through the miR-370-3p/BCL2L11 axis.

Isoflurane preconditioning attenuates OGD/R-induced cardiomyocyte cytotoxicity by regulating the miR-210/BNIP3 axis.

Isoflurane, a commonly used inhaled anesthetic, has been found to have a cardioprotective effect. However, the precise mechanisms have not been fully elucidated. Here, we found that isoflurane preconditioning enhanced OGD/R-induced upregulation of miR-210, a hypoxia-responsive miRNA, in AC16 human myocardial cells. To further test the roles of miR-210 in regulating the effects of isoflurane preconditioning on OGD/R-induced cardiomyocyte injury, AC16 cells were transfected with anti-miR-210 or control anti-miRNA. Results showed that isoflurane preconditioning attenuated OGD/R-induced cardiomyocyte cytotoxicity (as assessed by cell viability, LDH and CK-MB levels), which could be reversed by anti-miR-210. Isoflurane preconditioning also prevented OGD/R-induced increase in apoptotic rate, caspase-3 and caspase-9 activities, and Bax level and decrease in Bcl-2 expression level, while anti-miR-210 blocked these effects. We also found that anti-miR-210 prevented the inhibitory effects of isoflurane preconditioning on OGD/R-induced decrease in adenosine triphosphate content; mitochondrial volume; citrate synthase activity; complex I, II, and IV activities; and p-DRP1 and MFN2 expression. Besides, the expression of BNIP3, a reported direct target of miR-210, was significantly decreased under hypoxia condition and could be regulated by isoflurane preconditioning. In addition, BNIP3 knockdown attenuated the effects of miR-210 silencing on the cytoprotection of isoflurane preconditioning. These findings suggested that isoflurane preconditioning exerted protective effects against OGD/R-induced cardiac cytotoxicity by regulating the miR-210/BNIP3 axis.

ALDH2 mediates the effects of sodium-glucose cotransporter 2 inhibitors (SGLT2i) on improving cardiac remodeling

BackgroundSodium-glucose cotransporter-2 inhibitors (SGLT2i) are now recommended for patients with heart failure, but the mechanisms that underlie the protective role of SGLT2i in cardiac remodeling remain unclear. Aldehyde dehydrogenase 2 (ALDH2) effectively prevents cardiac remodeling. Here, the key role of ALDH2 in the efficacy of SGLT2i on cardiac remodeling was studied.MethodsAnalysis of multiple transcriptomic datasets and two-sample Mendelian randomization were performed to find out the differentially expressed genes between pathological cardiac hypertrophy models (patients) and controls. A pathological cardiac hypertrophy mouse model was established via transverse aortic constriction (TAC) or isoproterenol (ISO). Cardiomyocyte-specific ALDH2 knockout mice (ALDH2CMKO) and littermate control mice (ALDH2flox/flox) were generated to determine the critical role of ALDH2 in the preventive effects of dapagliflozin (DAPA) on cardiac remodeling. RNA sequencing, gene knockdown or overexpression, bisulfite sequencing PCR, and luciferase reporter assays were performed to explore the underlying molecular mechanisms involved.ResultsOnly ALDH2 was differentially expressed when the differentially expressed genes obtained via Mendelian analysis and the differentially expressed genes obtained from the multiple transcriptome datasets were combined. Mendelian analysis revealed that ALDH2 was negatively related to the severity of myocardial hypertrophy in patients. DAPA alleviated cardiac remodeling in mouse hearts subjected to TAC or ISO. ALDH2 expression was reduced, whereas ALDH2 expression was restored by DAPA in hypertrophic hearts. Cardiomyocyte specific ALDH2 knockout abolished the protective role of DAPA in preventing cardiac remodeling. ALDH2 expression and activity were increased in DAPA-treated neonatal rat primary cardiomyocytes (NRCMs), H9C2 cells and AC16 cells. Moreover, DAPA upregulated ALDH2 in peripheral blood mononuclear cells (PBMCs) from patients with type 2 diabetes. Sodium/proton exchanger 1 (NHE1) inhibition contributed to the regulation of ALDH2 by DAPA. DAPA suppressed the production of reactive oxygen species (ROS), downregulated DNA methyltransferase 1 (DNMT1) and subsequently reduced the ALDH2 promoter methylation level. Further studies revealed that DAPA enhanced the binding of nuclear transcription factor Y, subunit A (NFYA) to the promoter region of ALDH2, which was due to the decreased promoter methylation level of ALDH2.ConclusionsThe upregulation of ALDH2 plays a critical role in the protection of DAPA against cardiac remodeling. DAPA enhances the binding of NFYA to the ALDH2 promoter by reducing the ALDH2 promoter methylation level through NHE1/ROS/DNMT1 pathway.Graphical abstract

Network pharmacology and experimental study of Angelica sinensis and Astragalus membranaceus capsules in treating heart failure

ObjectiveThis study explores the mechanism of AAC in intervening heart failure (HF) using network pharmacology, molecular docking, and in vitro experimental validation. MethodsThe “active component-target” network and the “drug-disease target” protein interaction network were constructed using Cytoscape 3.9.0 and STRING Database. GO and KEGG enrichment analysis was performed using DAVID database. Then, the molecular docking of major compounds and target proteins was carried out using Autodock 1.5.7, and visualized with PyMOL 2.4.0 software. Finally, in vitro experimental validation was performed to explore the potential targets of AAC in treating HF. ResultsThe study revealed significant targets implicated in a variety of GO bioprocess programs and KEGG signaling networks. The primary chemicals to have strong binding ability with target proteins in molecular docking, with quercetin having the best binding energy with MAPK at −6.72 Kcal/Mol.Validation of cellular experiments showed that AAC might reduce the apoptosis that doxorubicin causes in AC16 cells by controlling the levels of PIK3CA, AKT1, and MAPK1. ConclusionThis study preliminarily reveals that AAC can treat HF through multiple components and multiple targets by using network pharmacology, molecular docking, and experimental validation.

The transcription factor PPARA mediates SIRT1 regulation of NCOR1 to protect damaged heart cells.

Heart failure (HF) is a clinical syndrome with a high risk. Our previous research showed a regulatory relationship between Sirtuin 1 (SIRT1), peroxisome proliferator-activated receptor α (PPARA) and nuclear receptor co-repressor 1 (NCOR1). This study aimed to investigate the regulatory mechanism of SIRT1/PPARA/NCOR1 axis in HF. HF models in vitro were established by doxorubicin (DOX)-induced AC16 and human cardiac microvascular endothelial cell (HCMEC) lines. The contents of atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), interleukin-1β (IL-1β), and IL-18 were detected using enzyme-linked immunosorbent assay. Then, we assessed the levels of reactive oxygen species (ROS), malondialdehyde (MDA), superoxide dismutase (SOD) and adenosine triphosphate (ATP). Moreover, the relationship between SIRT1 and PPARA was detected using the co-immunoprecipitation (Co-IP) analysis. The connection between PPARA and NCOR1 was analyzed using chromatin immunoprecipitation (ChIP). Overexpression of SIRT1 or PPARA could reduce apoptosis in DOX-induced AC16 and HCMEC cells, the levels of IL-1β, IL-18, ANP, BNP, ROS and MDA, while increasing the levels of SOD and ATP. In addition, overexpression of PPARA could increase the viability of DOX-induced cells and the levels of myosin heavy chain 6 (Myh6) and Myh7. Co-IP showed that SIRT1 interacted with PPARA. Silencing PPARA could reverse the effect of SIRT1 overexpression on DOX-induced AC16 and HCMEC cells. ChIP assay demonstrated that PPARA could bind to the promoter region of NCOR1. Silencing NCOR1 could reverse the effect of PPARA overexpression on DOX-induced AC16 and HCMEC cells. This study revealed that PPARA could mediate SIRT1 to promote NCOR1 expression and thus protect damaged heart cells. The finding provided an important reference for the treatment of HF.

Disruption of BACH1 Protects AC16 Cardiomyocytes Against Hypoxia/Reoxygenation-Evoked Injury by Diminishing CDKN3 Transcription.

Reperfusion after myocardial infarction (MI) can lead to myocardial ischemia/reperfusion (I/R) damage. The transcription factor (TF) broad-complex, tramtrack, and bric-a-brac (BTB) and cap'n'collar (CNC) homology 1 (BACH1) is implicated in the injury. However, the downstream mechanisms of BACH1 in affecting myocardial hypoxia/reoxygenation (H/R) damage are still fully understood. AC16 cells were stimulated with H/R conditions to model cardiomyocytes under H/R. mRNA analysis was performed by quantitative real-time PCR. Protein levels were gauged by immunoblot analysis. The effect of BACH1/cyclin-dependent kinase inhibitor 3 (CDKN3) on H/R-evoked injury was assessed by measuring cell viability via Cell Counting Kit-8 (CCK-8), apoptosis (flow cytometry and caspase 3 activity), ferroptosis via Fe2+, glutathione (GSH), reactive oxygen species (ROS) and malondialdehyde (MDA) markers and inflammation cytokines interleukin-1beta (IL-1β) and tumor necrosis factor alpha (TNF-α). The BACH1/CDKN3 relationship was examined by chromatin immunoprecipitation (ChIP) experiment and luciferase assay. BACH1 was increased in MI serum and H/R-stimulated AC16 cardiomyocytes. Functionally, disruption of BACH1 mitigated H/R-evoked in vitro apoptosis, ferroptosis and inflammation of AC16 cardiomyocytes. Mechanistically, BACH1 activated CDKN3 transcription and enhanced CDKN3 protein expression in AC16 cardiomyocytes. Our rescue experiments validated that BACH1 disruption attenuated H/R-evoked AC16 cardiomyocyte apoptosis, ferroptosis and inflammation by downregulating CDKN3. Additionally, BACH1 disruption could activate the adenosine monophosphate-activated protein kinase (AMPK) signaling by downregulating CDKN3 in H/R-stimulated AC16 cardiomyocytes. Our study demonstrates that BACH1 activates CDKN3 transcription to induce H/R-evoked damage of AC16 cardiomyocytes partially via AMPK signaling.

Bag2 protects against doxorubicin-induced cardiotoxicity by maintaining Pink1-mediated mitophagy

The clinical application of Doxorubicin (DOX) is limited due to its cardiotoxicity. Mitophagy dysfunction is the primary cause of DOX-induced cardiotoxicity (DIC). However, the precise mechanism by which DOX regulates mitophagy remains elusive. Bag2 (BCL2-associated athanogene 2) is a cochaperone implicated in multiple pathological states. The aim of this study was to investigate the potential cardio-protective effects of Bag2 in DIC. C57BL/6 mice and AC16 cells were used to establish DIC model. The expression of Bag2 were measured by western blotting and immunohistochemical. The effects of Bag2 on DIC were assessed through functional gain and loss experiments. Through in vitro and in vivo experiments, we found that Bag2 expression was significantly reduced after DOX treatment. Both Bag2 knockdown and DOX administration resulted in apoptosis, mitochondrial dysfunction, and impaired mitophagy. Conversely, Bag2 overexpression exerted protective effects against these phenotypes induced by DOX stimulation. Mechanistically, Bag2 maintained mitophagy activation by binding to Pink1 and protecting it from proteasome-dependent degradation, thereby preserving mitochondrial function and protecting against myocardial lesions. Our findings suggest that Bag2 may serve as a promising therapeutic target for the treatment of DIC.

TMT-based proteomics reveals methylprotodioscin alleviates oxidative stress and inflammation via COX6C in myocardial infraction

The effect of methylprotodioscin (MPD), a steroidal saponin obtained from medicinal plants, on myocardial infarction (MI) remains elusive. In this study, HL-1 and AC16 cells were subjected to injury induced by hypoxic environment, and a mouse model of MI was established by ligating the left anterior descending. MPD significantly increased viabilities and proliferations, improved the stability of MMP, reduced ROS and inflammatory factor levels in hypoxia cardiomyocytes. Moreover, MPD significantly improved cardiac functions, increased the ventricular ejection fraction and short axis shortening rate of mice with MI, reduced the infarction area, alleviated oxidative stress and increased ATPase activities. Then, differentially expressed proteins (DEPs) were discovered and evaluated using tandem mass tag (TMT)-based proteomics and bioinformatics approaches. Compared with sham group, there were 420 DEPs in the cardiac tissue of MI group, likewise, 163 DEPs in MPD group were identified compared to MI group. By validating, the expression of COX6C was elevated in MI group and declined in MPD groups, consistent with the TMT-based proteomics results. Correspondingly, p-NF-κB expression was downregulated, while Nrf2 and SOD expressions were upregulated by MPD. Moreover, si-COX6C transfection blocked the regulatory effects of MPD on COX6C-mediated inflammation and oxidative stress in MI. Our findings indicate that MPD, a naturally occurring active ingredient, could effectively improve cardiac function. Its ability may result from regulating COX6C to reduce oxidative stress and suppress inflammation, suggesting that MPD is very attractive for the treatment of MI.

Cardioprotective microRNAs (protectomiRs) in a pig model of acute myocardial infarction and cardioprotection by ischaemic conditioning: MiR-450a.

Cardioprotective miRNAs (protectomiRs) are promising therapeutic tools. Here, we aimed to identify protectomiRs in a translational porcine model of acute myocardial infarction (AMI) and to validate their cardiocytoprotective effect. ProtectomiR candidates were selected after systematic analysis of miRNA expression changes in cardiac tissue samples from a closed-chest AMI model in pigs subjected to sham operation, AMI and ischaemic preconditioning, postconditioning or remote preconditioning, respectively. Cross-species orthologue protectomiR candidates were validated in simulated ischaemia-reperfusion injury (sI/R) model of isolated rat ocardiomyocytes and in human AC16 cells as well. For miR-450a, we performed target prediction and analysed the potential mechanisms of action by GO enrichment and KEGG pathway analysis. Out of the 220 detected miRNAs, four were up-regulated and 10 were down-regulated due to all three conditionings versus AMI. MiR-450a and miR-451 mimics at 25 nM were protective in rat cardiomyocytes, and miR-450a showed protection in human cardiomyocytes as well. MiR-450a has 3987 predicted mRNA targets in pigs, 4279 in rats and 8328 in humans. Of these, 607 genes are expressed in all three species. A total of 421 common enriched GO terms were identified in all three species, whereas KEGG pathway analysis revealed 13 common pathways. This is the first demonstration that miR-450a is associated with cardioprotection by ischaemic conditioning in a clinically relevant porcine model and shows cardiocytoprotective effect in human cardiomyocytes, making it a promising drug candidate. The mechanism of action of miR-450a involves multiple cardioprotective pathways.

Tyrobp deficiency blocks NLRP3-mediated inflammation and pyroptosis to alleviate myocardial ischemia-reperfusion injury through regulating Syk

PurposeThe present study aims to investigate the biological function of Tyrobp in myocardial ischemia-reperfusion injury (MIRI) and to clarify its potential reaction mechanisms. MethodsAC16 cells were induced by oxygen-glucose deprivation/reoxygenation (OGD/R) to simulate the MIRI in vitro. The cell transfection technology was used to downregulate Tyrobp, followed by assessment of cell damage, apoptosis and cytokines production via Cell Counting Kit (CCK)-8 assay, lactate dehydrogenase (LDH) release assay, TUNEL and ELISA assays, respectively. Immunofluorescence assay was performed to assess GSDMD. Corresponding proteins were detected via western blotting, and Co-immunoprecipitation (Co-IP) assay was used to validate proteins interaction. ResultsTyrobp was upregulated in OGD/R-exposed AC16 cells, and Tyrobp deficiency significantly alleviated OGD/R-caused cell viability loss, LDH release and cell apoptosis in AC16 cells. Meanwhile, Tyrobp deficiency inhibited the activation of NLRP3 inflammasome, reduced the production of cytokines and inhibited GSDMD intensity and GSDMD-N expression. Additionally, Tyrobp could interact with Syk and regulate Syk/NF-κB signaling. The rescue experiments showed that the above effects of Tyrobp deficiency on OGD/R-exposed AC16 cells were partly weakened by Syk overexpression. ConclusionTyrobp deficiency alleviated MIRI by inhibiting NLRP3-mediated inflammation and pyroptosis through regulating Syk, providing a novel target for the treatment of MIRI.

Methyltransferase METTL3 governs the modulation of SH3BGR expression through m6A methylation modification, imparting influence on apoptosis in the context of Down syndrome-associated cardiac development

Down syndrome (DS), caused by an additional chromosome 21, has a high risk of congenital heart defects (CHD), one of the primary causes of mortality in DS newborns. To elucidate the pathogenetic mechanisms underlying this condition, we explored the role of RNA m6A methylation, regulated by METTL3, in DS cardiac development and its impact on the expression of SH3BGR, a gene located at Down syndrome congenital heart disease (DS-CHD) minimal region. We analyzed DS fetal cardiac tissues to assess RNA m6A methylation levels and identify potential contributors. RNA sequencing was performed to detect differentially expressed genes in the same tissues. To further understand METTL3’s function in heart development, we inactivated Mettl3 in the developing mouse heart to mimic the significantly reduced METTL3 observed in DS cardiac development. Additionally, human cardiomyocyte AC16 cells were used to investigate the molecular mechanism by which METTL3 regulates SH3BGR expression. Apoptosis was analyzed to evaluate METTL3’s effect on heart development through SH3BGR regulation. Reduced m6A modification and decreased METTL3 expression were observed in human DS fetal hearts, along with a significant increase of SH3BGR expression. METTL3, through m6A modification, was found to regulate SH3BGR expression, by influencing mRNA stability. METTL3-deficient mouse embryos exhibited heart malformation with increased apoptosis, emphasizing its role in heart development. In DS hearts, METTL3 downregulation and SH3BGR upregulation, potentially orchestrated by abnormal m6A modification, contribute to gene dysregulation and apoptosis. This study reveals novel insights into DS cardiac pathology, highlighting the intricate role of METTL3 in DS congenital heart defects and presenting the m6A modification of SH3BGR as a potential therapeutic target.

The Role and Mechanism of circAMOTL1 in Hypertensive Heart Failure

To explore the changes of circAMOTL1 expression, cell function and expression of fibrosis-related proteins in myocardial hypertrophy and fibrosis model. Human cardiomyocytes AC16 were cultured, and the concentration of Ang II was firstly explored by CCK-8. After determining the optimal dose of Ang II, AC16 cells were induced to construct an in vitro model of myocardial hypertrophy and fibrosis. CCK-8 was utilized to assess cell proliferation. Flow cytometry was performed to validate cell cycle and apoptosis. circAMOTL1, miR-330-3p, smad7, Col1a2 and Col3a1 genes expressions were assessed by qRT-PCR. smad7, Col1a2 and Col3a1 proteins expressions were evaluated using Western blot and IF. FISH was performed to detect circAMOTL1 localization in cells. 10 μM Ang II was selected for subsequent experiments. Compared with control group, cell viability of the Ang II group was significantly decreased, apoptosis was observably increased, circAMOTL1 and smad7 expressions were signally repressed, miR-330-3p, Col1a2 and Col3a1 expressions were notably increased. Both circAMOTL1 and miR-330-3p, miR-330-3p and smad7 had targeted binding sites. Overexpression of circAMOTL1 promoted AC16 cells proliferation and inhibited apoptosis. In addition, overexpression of circAMOTL1 inhibited miR-330-3p and promoted smad7 expression. Overexpression of circAMOTL1 inhibited miR-330-3p and promoted smad7 expression. circAMOTL1 may be a potential target for treating hypertensive heart failure.

The Role of miRNA-29b1 on the Hypoxia-Induced Apoptosis in Mammalian Cardiomyocytes

A hypoxic stress which causes apoptosis of cardiomyocytes is the main problem in the ischemic heart disease. The present research sought to investigate the role of microRNA-29b1 (miR-29b1) in hypoxia-treated cardiomyocytes and its potential mechanism involved. We replicated an in vitro AC16 and H9C2 cardiomyocytes ischemia model by hypoxia (1% O2, 48 h) treatment. Cell apoptosis was evaluated by flow cytometry using Annexin V FITC-PI staining assay. Moreover, we used western blot and immunofluorescence analysis to determine the expression of Bcl-2, Bax caspase-3 and Cx43 proteins. We found that miR-29b1 protected AC16 and H9C2 cells from hypoxia-induced injury as the evidences that miR-29b1 attenuated the effects of hypoxia treatment on AC16 and H9C2 cell apoptosis after hypoxia treatment. In conclusion, these results revealed the potential cardiovascular protective effects of miR-29b1 in the process of ischemia-related myocardial injury.

Abstract Tu142: Pannexin-2 Deficiency Exacerbates Stress-induced Cell Injury in Cardiomyocytes

Pannexins are a family of channel proteins involved in a variety of biological processes, including cell death signaling and immune functions. While Pannexin isoforms 1 and 3 have been widely studied, mainly in the brain, much less is known about the role of isoform 2 (Pannexin2, or Panx2). A recent study showed that deficiency in Panx2 sensitizes pancreatic beta cells to cytokine-induced apoptosis, while another study revealed that Panx2 promotes ultraviolet-induced apoptosis in keratinocytes. The role of Panx2 in the regulation of cardiomyocyte function has not been investigated. In the current study, we explored the subcellular distribution profile of Panx2 expression in cardiomyocytes (AC16 cells and adult cardiomyocytes) and examined the role of Panx2 in regulating cardiomyocyte response to stress. Western blotting analysis revealed palmitoylation of Panx2 in the heart, suggesting that this channel is located intracellularly, instead of in the plasma membrane. Confocal imaging revealed that Panx2 expression is in the proximity of the sarcoplasmic reticulum and mitochondria, confirming its intracellular localization. The stress test results indicated that the knockdown of Panx2 by siRNA exacerbated FCCP-reduced oxidative stress and cell injury in AC16 cells. Similarly, adult cardiomyocytes isolated from Panx2-KO mice were more vulnerable to ischemia-reperfusion injury compared with wild-type cells. Finally, we found that the level of Panx2 expression altered in the cardiac tissue of a mouse model with pressure overload-induced heart failure, implying that Panx2 may be involved in the pathological remodeling of a failing heart.

Abstract Tu131: Counteracting Cardiac Ischemia and Reperfusion Injury: the role of Sialidase Neu3

Coronary reperfusion procedures are crucial for restoring blood flow to the heart tissue after an acute myocardial infarction. However, they also lead to ischemia and reperfusion injury (IRI), which exacerbate the damage and promote heart failure. Despite the urgent need for cardioprotective strategies against IRI, none have been clinically implemented, emphasizing the need for a comprehensive understanding of the pathophysiology of IRI. Our research team found that sialidase Neu3, an enzyme responsible for the removal of sialic acid from glycosphingolipids, is modulated during IRI in vivo. Constitutive overexpression of Neu3 in rat cardiomyoblasts was shown to attenuate IRI through activation of the reperfusion injury salvage kinase (RISK) and HIF-1α signaling pathways. To further investigate the role of Neu3 in promoting cardioprotection, in this study we developed an inducible Neu3 overexpression model in human cardiac cells and mice. Inducible upregulation of Neu3 significantly improved cell resistance and reduced oxidative stress in AC16 cells exposed to IRI in vitro. These effects were attributed to Neu3-mediated maintenance of mitochondrial membrane potential, which was impaired in control cells. When looking at the upregulated genes exclusively in cells overexpressing the sialidase Neu3, RNAseq analysis revealed the predominant activation of MAP kinases typical of the RISK pathway. We also generated, for the first time, αMHC-Cre/LSL-Neu3 mice overexpressing Neu3 in an inducible and cardiomyocyte-specific manner. These mice showed no significant differences in cardiac morphology and functionality compared to wild-type animals. However, the Neu3-overexpressing mice exhibited a significant reduction in infarct size and improved cardiac functionality after surgical induction of IRI. These results suggest that Neu3 is a promising target for improving cardioprotection and attenuating the incidence and severity of myocardial infarction.

Quercetin Alleviates LPS-Stimulated Myocardial Injury through Regulating ALOX5/PI3K/AKT Pathway in Sepsis.

Quercetin (QUE) has been found to inhibit the progression of sepsis-related diseases, including sepsis-induced cardiomyopathy (SIC). More information about the role and mechanism of QUE in SIC progression deserves further exploration. Human cardiomyocytes (AC16) were induced with LPS to mimic SIC cell models. Cell proliferation and apoptosis were determined using CCK8 assay, EdU assay, and flow cytometry. Cell inflammation and ferroptosis were evaluated by detecting IL-1β, TNF-α, Fe2+, ROS, GSH, and GPX4 levels. 5-lipoxygenase (ALOX5) expression was examined by quantitative real-time PCR and western blot. LPS treatment reduced AC16 cell proliferation, while enhanced apoptosis, inflammation, and ferroptosis. QUE repressed LPS-induced AC16 cell apoptosis, inflammation, and ferroptosis. ALOX5 was upregulated in SIC patients, and its expression was reduced by QUE. ALOX5 knockdown restrained LPS-induced apoptosis, inflammation, and ferroptosis in AC16 cells. The inhibitory effect of QUE on LPS-induced myocardial injury could be reversed by ALOX5 overexpression. QUE promoted the activity of PI3K/AKT pathway by reducing ALOX5 expression. QUE could alleviate LPS-induced myocardial injury by regulating ALOX5/PI3K/AKT pathway, suggesting that QUE might be used for treating SIC.

ELF5-Regulated lncRNA-TTN-AS1 Alleviates Myocardial Cell Injury via Recruiting PCBP2 to Increase CDK6 Stability in Myocardial Infarction.

Myocardial infarction (MI) seriously threatens the health of elderly people, and reducing myocardial injury is of great significance for the treatment of MI. LncRNA-TTN-AS1 shows protective effects on cardiomyocyte injury, while the role of TTN-AS1 in MI remains unknown. CCK8, flow cytometry, and JC-1 staining assessed cell viability, apoptosis and mitochondrial membrane potential (MMP), respectively. Cellular reactive oxygen species (ROS) and secreted lactate dehydrogenase (LDH) levels were measured. The interactions between ELF5, TTN-AS1, PCBP2 and CDK6 were explored using ChIP, luciferase reporter assay, RIP, and pull-down. The severity of MI in mice was evaluated using TTC, H&E, and TUNEL staining. The data revealed that OGD/R significantly induced ROS, mitochondrial injury and apoptosis in AC16 cells, while overexpression of ELF5 or TTN-AS1 reversed these phenomena. ELF5 transcriptionally activated TTN-AS1 through binding with its promoter. TTN-AS1 increased CDK6 stability via recruiting PCBP2. CDK6 knockdown abolished the inhibitory effects of TTN-AS1 overexpression on OGD/R-induced myocardial injury. Furthermore, overexpression of TTN-AS1 or ELF5 alleviated MI progression in mice by upregulating CDK6. Collectively, TTN-AS1 transcriptionally regulated by ELF5 alleviated myocardial apoptosis and injury during MI via recruiting PCBP2 to increase CDK6 stability, which shed new lights on exploring new strategies against MI.

Role of mitochondrial ribosomal protein L7/L12 (MRPL12) in diabetic ischemic heart disease

BackgroundMyocardial infarction (MI) is a significant cause of death in diabetic patients. Growing evidence suggests that mitochondrial dysfunction contributes to heart failure in diabetes. However, the molecular mechanisms of mitochondrial dysfunction mediating heart failure in diabetes are still poorly understood. MethodsWe examined MRPL12 levels in right atrial appendage tissues from diabetic patients undergoing coronary artery bypass graft (CABG) surgery. Using AC-16 cells overexpressing MRPL12 under normal and hyperglycemic conditions we performed mitochondrial functional assays OXPHOS, bioenergetics, mitochondrial membrane potential, ATP production and cell death. ResultsWe observed elevated MRPL12 levels in heart tissue samples from diabetic patients with ischemic heart disease compared to non-diabetic patients. Overexpression of MRPL12 under hyperglycemic conditions did not affect oxidative phosphorylation (OXPHOS) levels, cellular ATP levels, or cardiomyocyte cell death. However, notable impairment in mitochondrial membrane potential (MMP) was observed under hyperglycemic conditions, along with alterations in both basal respiration oxygen consumption rate (OCR) and maximal respiratory capacity OCR. ConclusionsOverall, our results suggest that MRPL12 may have a compensatory role in the diabetic myocardium with ischemic heart disease, suggesting that MRPL12 may implicate in the pathophysiology of MI in diabetes.

Resveratrol Mitigates Ischemia/Reperfusion-Induced Cardiomyocyte Injury by Inhibiting the Expression of Superoxide Dismutase 2

Resveratrol exhibits antioxidant, anti-inflammatory, and potentially cardio-protective properties. However, the effectiveness of resveratrol in acute myocardial infarction (AMI)-induced cardiomyocyte injury remains unclear. Superoxide Dismutase 2 (SOD2) is an important antioxidant enzyme in the mitochondria. However, few studies have reported the impact of SOD2 on AMI-induced cardiomyocyte injury. Therefore, we establish an in vitro model of cardiomyocyte ischemia/reperfusion (I/R) injury using oxygen-glucose deprivation/reoxygenation (OGD/R) to investigate the protective effects of resveratrol against OGD/R-induced cardiomyocyte injury and its underlying regulatory mechanism. Cell viability was assessed using the CCK-8. Apoptosis was evaluated by TUNEL staining. The levels of Cleaved cas-3, Bcl2, and SOD2 an important antioxidant enzyme in the mitochondria that is responsible for eliminating superoxide radicals were analyzed by western blot. The ROS positive rate was using a ROS/Superoxide detection assay kit. The relative abundance of the SOD2 mRNA was determined using the 2−ΔΔCT method. We demonstrated that OGD/R treatment significantly reduced AC16 cell viability while increasing apoptosis levels, oxidative stress, and inflammatory factor levels. We further confirmed the upregulation of SOD2 by OGD/R treatment, suggesting its potential involvement in modulating OGD/R-induced AC16 cell injury. Additionally, silencing SOD2 ameliorated the detrimental effects of OGD/R on AC16 cells. Moreover, we observed that upregulation of SOD2 aggravated OGD/R-induced AC16 cell injury, and resveratrol effectively reduced OGD/R-induced AC16 cell injury by down-regulating SOD2. In conclusion, this research provides a promising therapeutic strategy for mitigating I/R damage in AMI-induced cardiomyocytes, thereby identifying a potential target for therapeutic intervention.

The role of miRNA-29b1 on the hypoxia-induced apoptosis in mammalian cardiomyocytes.

Cardiomyocyte apoptosis is a complex biological process involving the interaction of many factors and signaling pathways. In hypoxic environment, cardiomyocytes may trigger apoptosis due to insufficient energy supply, increased production of oxygen free radicals, and disturbance of intracellular calcium ion balance. The present research aimed to investigate the role of microRNA-29b1 (miR-29b1) in hypoxia-treated cardiomyocytes and its potential mechanism involved. We established an in vitro ischemia model using AC16 and H9C2 cardiomyocytes through hypoxia treatment (1% O2, 48 h). Cell apoptosis was evaluated by flow cytometry using Annexin V FITC-PI staining assay. Moreover, we used Western blot and immunofluorescence analysis to determine the expression of Bcl-2, Bax caspase-3 and Cx43 proteins. We found that miR-29b1 protected AC16 and H9C2 cells from hypoxia-induced injury as evidence that miR-29b1 attenuated the effects of hypoxia treatment on AC16 and H9C2 cell apoptosis after hypoxia treatment. In conclusion, our findings suggest that miR-29b1 may have potential cardiovascular protective effects during ischemia-related myocardial injury.