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Heart failure tends to deteriorate in colder climates, heightening the risk of major adverse cardiovascular events. Brown adipose tissue (BAT) serves as both a thermogenic organ and an atypical site for triiodothyronine (T3) synthesis in response to cold. This study investigates the potential role of BAT in contributing to abdominal aortic constriction (AAC)-induced pathological cardiac remodeling during cold exposure. In this study, we developed a mouse model of pathological cardiac remodeling using AAC. Physical excision of interscapular BAT (iBATx) was performed during cold exposure, and T3 synthesis levels were measured. Additionally, the impact of uncoupling protein 1 (UCP1) knockout on thermogenic function and pathological cardiac remodeling was investigated. In vitro studies were conducted to assess the effect of T3 on cardiomyocyte hypertrophy induced by phenylephrine (PE). Physical removal of interscapular BAT during cold exposure decreased T3 synthesis and mitigated pathological cardiac remodeling. Conversely, UCP1 knockout eliminated thermogenic function during cold exposure, while preserving BAT integrity increased T3 synthesis and exacerbated pathological cardiac remodeling. In vitro, T3 further aggravated cardiomyocyte hypertrophy caused by PE. These findings underscore the distinct effects of physical and functional BAT ablation on pathological cardiac remodeling, primarily through altering T3 levels rather than thermogenesis in cold environments. This research provides new insights into the differential roles of BAT in cardiac health, particularly under cold exposure conditions., Competing Interests: Declaration of competing interest All authors state that there are no conflicts of interest., (Copyright © 2024. Published by Elsevier Inc.)

Piezo1 channels are activated by mechanical stress and play a significant role in cardiac hypertrophy and fibrosis. However, the molecular mechanisms underlying Piezo1 activation on the cell membrane following pressure overload remain unclear. Caveolae are known to mitigate mechanical forces and regulate Piezo1 function. Therefore, this study aimed to investigate the interaction between caveolae and Piezo1 in the development of pressure overload-induced cardiac remodeling. We observed reduced colocalization between Piezo1 and Caveolin-3 in hypertrophic cardiomyocytes following abdominal aortic constriction and Angiotensin-II treatment, accompanied by increased Piezo1 function and expression. Furthermore, enhanced Piezo1 function was also noted upon caveolae disruption using methyl-beta-cyclodextrin (mβCD). Thus, our findings suggested that pressure overload led to Piezo1 translocation from caveolae, thereby augmenting its function and expression, which may contribute to cardiac remodeling., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Objectives: Flavonoid compounds exhibit remarkable antioxidant and anti-inflammatory properties in DCM and various other diseases. However, the specific mechanisms by which Tricin, 4',5,7-trihydroxy-3',5'-dimethoxyflavone, exerts its effects in the context of DCM remain to be elucidated., Methods: Rat H9C2 cells were cultured and subjected to high glucose conditions to establish a DCM cell model. Tricin was administered in varying concentrations to evaluate its effects on cellular oxidative stress markers, including ROS, LDH, and SOD. Additionally, the levels of inflammatory cytokines TNF-α, IL-1β, and IL-6, as well as the expression of TLR4, MYD88, and p-NF-κB, were assessed through ELISA and Western blotting., Results: Tricin treatment significantly ameliorated high glucose-induced oxidative stress in H9C2 cells, evidenced by reduced ROS and LDH levels and increased SOD levels in a dose-dependent manner. Furthermore, Tricin effectively suppressed the elevation of pro-inflammatory cytokines TNF-α, IL-1β, and IL-6. Tricin also inhibited the overactivation of the TLR4-MYD88-NF-κB signaling pathway, suggesting its role in modulating key inflammatory processes in DCM., Conclusions: Tricin exhibits a protective role against high glucose-induced cardiac damage in a DCM cell model. By reducing oxidative stress and inflammation, and inhibiting the TLR4-MYD88-NF-κB pathway, Tricin shows significant therapeutic potential for DCM treatment. This study underscores the value of Tricin as a novel therapeutic approach for managing diabetic cardiomyopathy, warranting further research and clinical investigation., Clinical Trial Number: Not applicable., Competing Interests: Declarations. Ethics approval and consent to participate: Not applicable. Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

Background: Pathological cardiac hypertrophy stands as a pivotal mechanism contributing to diverse cardiovascular diseases, ultimately leading to heart failure. Despite its clinical significance, the intricate molecular mechanisms instigating pathological cardiac hypertrophy remain inadequately understood. In this study, we aim to further reveal its complex pathogenesis by exploring the role of Fas apoptotic inhibitory molecule 2 (FAIM2) in modulating pathological cardiac hypertrophy., Methods and Results: We used phenylephrine-induced hypertrophic cardiomyocytes and also generated cardiac-specific knockout mice and adeno-associated virus serotype 9-Faim2 mice to evaluate the function of FAIM2 in pathological myocardial hypertrophy. Furthermore, unbiased RNA-sequencing analysis was used to identify the direct target and corresponding molecular events contributing to FAIM2 function. Ultimately, our study revealed a downregulation of FAIM2 expression in phenylephrine-induced hypertrophic cardiomyocytes and pressure overload-induced hypertrophic hearts. FAIM2 exhibited a significant attenuation of phenylephrine-induced enlargement of primary neonatal rat cardiomyocytes, whereas FAIM2 knockdown aggravated the hypertrophic response. Furthermore, Faim2 gene knockout significantly exacerbated cardiac hypertrophy and heart fibrosis in vivo. Mechanistic investigations unveiled that FAIM2 exerts its inhibitory effect by suppressing TAK1-JNK1/2-p38 MAPK signaling cascades, thereby mitigating cardiac hypertrophy., Conclusions: Our findings position FAIM2 as a novel negative regulator of pathological cardiac hypertrophy through its inhibitory action on mitogen-activated protein kinase signaling activation. This identification of FAIM2's role provides crucial insights that may pave the way for the development of effective therapeutic strategies aimed at mitigating pathological cardiac hypertrophy, addressing a critical need in cardiovascular disease management.

Myocardial ischemia-reperfusion (I/R) injury caused by revascularization treatment is the leading cause of cardiac damage aggravation in ischemic heart disease. Increasing evidence has unraveled the crucial role of pyroptosis in myocardial I/R injury. Of note, lactylation has been validated to be participated in modulating pyroptosis. Hence, this study was aimed to elaborate the potential and mechanism of lactylation in myocardial I/R damage. We established the cell model of I/R through inducing hypoxia/reoxygenation (H/R) of H9c2 cells. It was uncovered that H/R stimulation drove cardiomyocyte pyroptosis and upregulated total lactylation level. Further, we demonstrated that promoting lactylation contributed to H/R-evoked pyroptosis, whereas silencing LDHA led to the opposite results. More than that, LDHA was confirmed to facilitate lactylation of NLRP3 at K245 site and increase its protein stability. Our findings indicated that activation of NLRP3 abolished the function of LDHA deficiency in H/R-treated H9c2 cells. In concert with the aforementioned outcomes, knockout of LDHA attenuated the infarct size and myocardial damage in I/R mice and upregulation of NLRP3 counteracted the effects of LDHA knockout on I/R-evoked injury in vivo. To summarize, the current research provided persuasive evidence that LDHA promoted myocardial I/R damage via enhancing NLRP3 lactylation to induce cardiomyocyte pyroptosis., Competing Interests: Declarations Ethics approval and consent to participate The study was approved by the Ethics Committee of MDKN Biotechnology Co., Lt (MDKN-2023-307, 2023.11.02). All experiments were performed in accordance with relevant guidelines and regulations. Consent for publication Not applicable. Clinical trial number Not applicable. Competing interests The authors declare no competing interests., (© 2024. The Author(s).)

Myocardial ischemia-reperfusion injury (MIRI) is a significant risk factor for acute myocardial infarction and is closely associated with ferroptosis. This study aimed to identify key ferroptosis-related genes as potential diagnostic markers for MIRI and to explore their roles in immune infiltration and therapeutic targeting in myocardial tissue. We obtained single-cell RNA sequencing (scRNA-seq) and RNA-seq data on MIRI from the GEO database, applied Seurat and UMAP for data processing and clustering, and analyzed ligand-receptor interactions using CellPhoneDB. By scoring ferroptosis in cardiomyocytes, we identified differentially expressed genes and conducted GO and KEGG pathway analyses. A protein interaction network was then constructed using the STRING database, and seven key genes (Atp5h, Vdac2, Pkm, Cycs, Hspa8, Tpi1, Ldha) were identified through Lasso regression modeling, showing significant associations with immune responses. In vivo experiments in a mouse ischemia-reperfusion model confirmed the roles of these seven genes in MIRI via RT-qPCR. To further investigate the role of Hspa8 in ferroptosis and MIRI, siRNA knockdown experiments were performed in H9C2 rat cardiomyocytes, and its involvement in ferroptosis was validated by JC-1 staining and PCR analysis. This study reveals the importance of ferroptosis-related genes in MIRI through integrated bioinformatics and experimental approaches, offering new insights into diagnostic markers and immune-related therapeutic targets for MIRI., (© 2024 The Author(s). The FASEB Journal published by Wiley Periodicals LLC on behalf of Federation of American Societies for Experimental Biology.)

Introduction: Persistent chronic myocardial hypoxia causes disturbances in mitochondrial quality control (MQC), ultimately leading to increased cardiomyocyte injury in patients with Tetralogy of Fallot (TOF). The present study aimed to identify the key effector molecules of cardiomyocyte injury under chronic hypoxia in TOF., Methods: Clinical data from TOF patients were collected and whole transcriptome sequencing was performed on myocardial samples. Chronic hypoxia models were established in cardiac-specific knockout mice and cardiomyocytes, and a series of molecular experiments were used to determine the specific mechanisms involved., Results: Clinical cohort data and whole-transcriptome sequencing analysis of myocardial samples from TOF patients revealed that forkhead box O1 (FOXO1) plays an important role in chronic hypoxic cardiomyocyte injury. In a model of chronic hypoxia established in FOXO1 cardiac-specific knockout mice and FOXO1 gene-deficient cardiomyocytes, the AMPK signaling pathway regulates the expression of FOXO1, which in turn disrupts MQC by regulating the transcriptional activation of Rho-associated protein kinase 1 (ROCK1), and increasing the production of mitochondrial ROS, thereby exacerbating damage to cardiomyocytes. Excessive reactive oxygen species (ROS) production during MQC dysfunction further activates Cox7a2L to increase the assembly of the respiratory chain supercomplex. In addition, we found that miR-27b-3p partially binds to the 3' untranslated region of FOXO1 to exert a protective effect., Conclusions: Maintenance of MQC under chronic hypoxia is achieved through a series of injury-protection mechanisms, suggesting that FOXO1 inhibition may be crucial for future mitigation of chronic hypoxic cardiomyocyte injury in TOF., Competing Interests: Declaration of competing interest The authors declare no competing interests., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Cardiovascular diseases (CVD) are the leading cause of death worldwide, and advanced age is a main contributor to the prevalence of CVD. Cellular senescence is an irreversible state of cell cycle arrest that occurs in old age or after cells encounter various stresses. Senescent cells not only result in the reduction of cellular function, but also produce senescence-associated secretory phenotype (SASP) to affect surrounding cells and tissue microenvironment. There is increasing evidence that the gradual accumulation of senescent cardiomyocytes is causally involved in the decline of cardiovascular system function. To highlight the role of senescent cardiomyocytes in the pathophysiology of age-related CVD, we first introduced that senescent cardiomyoyctes can be identified by structural changes and several senescence-associated biomarkers. We subsequently provided a comprehensive summary of existing knowledge, outlining the compelling evidence on the relationship between senescent cardiomyocytes and age-related CVD phenotypes. In addition, we discussed that the significant therapeutic potential represented by the prevention of accelerated senescent cardiomyocytes, and the current status of some existing geroprotectors in the prevention and treatment of age-related CVD. Together, the review summarized the role of cardiomyocyte senescence in CVD, and explored the molecular knowledge of senescent cardiomyocytes and their potential clinical significance in developing senescent-based therapies, thereby providing important insights into their biology and potential therapeutic exploration., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared toinfluence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Ethnopharmacological Relevance: Radiation-induced heart disease (RIHD) is one of the most serious complications in patients receiving chest radiotherapy, partially offsetting its benefits. At present, there is a lack of effective treatments for RIHD. Ferroptosis is a newly discovered type of cell death that results from iron-dependent lipid peroxide accumulation. It was recently shown that irradiation generates severe ferroptosis, providing new insights for the treatment of RIHD. Abelmoschus manihot (L.) possesses excellent pharmacological properties and is widely used in treating various ischemic heart and brain diseases; however, its efficacy and mechanism in treating RIHD are unknown., Aim: This study aimed to investigate the efficacy and mechanism of total extracts from A. manihot (L.) (TEA) in treating RIHD., Materials and Methods: C57BL/6 mice and H9C2 cells were exposed to irradiation to induce RIHD in vivo and in vitro, respectively. In vivo, we evaluated the protective effects of TEA (150 and 300 mg/kg) on RIHD. Body and heart weight changes of mice were calculated in each group, and malondialdehyde (MDA) level, glutathione/oxidized glutathione (GSH/GSSH) and nicotinamide adenine dinucleotide phosphate (NADPH/NADP + ) ratios, western blot, heart histology, and immunohistochemistry were used to evaluate TEA effectiveness. We identified the potential mechanism of radiation-induced cardiomyocyte injury in H9C2 cells treated with small interfering RNA. We determined the effective dose of TEA (0.6 mg/mL) using a Cell Counting Kit-8 assay. Intracellular Fe 2+ and lipid peroxidation levels were detected by Phen Green™ SK diacetate probe, BODIPY 581/591 C11 staining, and MDA, GSH, and NADPH kits, and the level of target protein was evaluated by immunofluorescence and western blot., Results: Radiation inhibited system Xc-cystine (xCT)/glutathione peroxidase 4 (GPX4) expression and activity in cardiomyocytes in a time and dose-dependent manner. After silencing xCT/GPX4, MDA significantly increased and GSH/GSSH and NADPH/NADP +  ratios were reduced. xCT/GPX4 inhibition drove ferroptosis in radiation-induced H9C2 injury. Oxidative stress in H9C2 was significantly enhanced by irradiation, which also significantly increased NADPH oxidase 4 (NOX4) expression and inhibited nuclear factor E2-related factor 2 (Nrf2) expression in vivo and in vitro. Inhibition of xCT/GPX4 drove ferroptosis in radiation-induced H9C2 injury, which was aggravated by inactivation of Nrf2 and alleviated by inhibition of NOX4. Compared with the ionizing radiation-only group, TEA improved body weight loss, MDA levels, and histological changes induced by irradiation in mice hearts, and increased the ratio of GSH/GSSH and NADPH/NADP + in vivo; it also reduced lipid peroxidation and intracellular Fe 2+ accumulation, restored MDA levels, and elevated the ratios of GSH/GSSH and NADPH/NADP + in irradiation-injured H9C2 cells. TEA up-regulated Nrf2, xCT, and GPX4 expression and inhibited NOX4 expression in vivo and in vitro., Conclusions: Ferroptosis induced by redox imbalance mediated through the NOX4/xCT/GPX4 axis is a potential mechanism behind radiation-induced cardiomyocyte injury, and can be prevented by TEA., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

Background: Circular RNAs (circRNAs) are differentially expressed in various cardiovascular diseases, including myocardial infarction (MI) injury. However, their functional role in necroptosis-induced loss of cardiomyocytes remains unclear. We identified a cardiac necroptosis-associated circRNA transcribed from the Cacna1c gene (circCacna1c) to investigate the involvement of circRNAs in cardiomyocyte necroptosis., Methods: To investigate the role of circCacna1c during oxidative stress, H9c2 cells and neonatal rat cardiomyocytes were treated with hydrogen peroxide (H 2 O 2 ) to induce reactive oxygen species (ROS)-induced cardiomyocyte death. The N 6 -methyladenosine (m 6 A) modification level of circCacna1c was determined by methylated RNA immunoprecipitation quantitative polymerase chain reaction (MeRIP-qPCR) analysis. Additionally, an RNA pull-down assay was performed to identify interacting proteins of circCacna1c in cardiomyocytes, and the regulatory role of circCacna1c in target protein expression was tested using a western blotting assay. Furthermore, the MI mouse model was constructed to analyze the effect of circCacna1c on heart function and cardiomyocyte necroptosis., Results: The expression of circCacna1c was found to be reduced in cardiomyocytes exposed to oxidative stress and in mouse hearts injured by MI. Overexpression of circCacna1c inhibited necroptosis of cardiomyocytes induced by hydrogen peroxide and MI injury, resulting in a significant reduction in myocardial infarction size and improved cardiac function. Mechanistically, circCacna1c directly interacts with heterogeneous nuclear ribonucleoprotein F (Hnrnpf) in the cytoplasm, preventing its nuclear translocation and leading to reduced Hnrnpf levels within the nucleus. This subsequently suppresses Hnrnpf-dependent receptor-interacting protein kinase 1 (RIPK1) expression. Furthermore, fat mass and obesity-associated protein (FTO) mediates demethylation of m 6 A modification on circCacna1c during necrosis and facilitates degradation of circCacna1c., Conclusion: Our study demonstrates that circCacna1c can improve cardiac function following MI-induced heart injury by inhibiting the Hnrnpf/RIPK1-mediated cardiomyocyte necroptosis. Therefore, the FTO/circCacna1c/Hnrnpf/RIPK1 axis holds great potential as an effective target for attenuating cardiac injury caused by necroptosis in ischemic heart disease., Competing Interests: Declarations Ethics approval and consent to participate All animal protocols in this study were performed in accordance with the Basel Declaration and the approval of the Ethics Committee of Medical College of the Qingdao University (Number: QDU-AEC-2022329, Date: July 4th, 2022). Consent for publication Not applicable. Competing interests The authors have declared that no competing interest exists., (© 2024. The Author(s).)

Skeletal muscle actin (ACTA1) mutations are a prevalent cause of skeletal myopathies consistent with ACTA1's high expression in skeletal muscle. Rare de novo mutations in ACTA1 associated with combined cardiac and skeletal myopathies have been reported, but ACTA1 represents only ~20% of the total actin pool in cardiomyocytes, making its role in cardiomyopathy controversial. Here we demonstrate how a mutation in an actin isoform expressed at low levels in cardiomyocytes can cause cardiomyopathy by focusing on a unique ACTA1 variant, R256H. We previously identified this variant in a family with dilated cardiomyopathy, who had reduced systolic function without clinical skeletal myopathy. Using a battery of multiscale biophysical tools, we show that R256H has potent effects on ACTA1 function at the molecular scale and in human cardiomyocytes. Importantly, we demonstrate that R256H acts in a dominant manner, where the incorporation of small amounts of mutant protein into thin filaments is sufficient to disrupt molecular contractility, and that this effect is dependent on the presence of troponin and tropomyosin. To understand the structural basis of this change in regulation, we resolved a structure of R256H filaments using cryoelectron microscopy, and we see alterations in actin's structure that have the potential to disrupt interactions with tropomyosin. Finally, we show that ACTA1 R256H/+ human-induced pluripotent stem cell cardiomyocytes demonstrate reduced contractility and sarcomeric organization. Taken together, we demonstrate that R256H has multiple effects on ACTA1 function that are sufficient to cause reduced contractility and establish a likely causative relationship between ACTA1 R256H and clinical cardiomyopathy., Competing Interests: Competing interests statement:The authors declare no competing interest.

Aim: Mitochondrial dysfunction is a critical factor in the pathogenesis of septic cardiomyopathy (SCM). Mitochondrial anchored protein ligase (MAPL), a small ubiquitin-like modifier (SUMO) E3 ligase, plays a significant role in mitochondrial function. However, the role of MAPL in SCM remains unclear., Methods: To investigate the role of MAPL in SCM, cardiomyocyte-specific MAPL knockout mice were generated. A cecal ligation and puncture (CLP) procedure was employed to induce a sepsis-like condition., Results: The expression of MAPL in heart tissues and H9C2 cardiomyocytes was elevated following CLP challenge or lipopolysaccharide (LPS) stimulation. MAPL deficiency ameliorated CLP-induced cardiac injury, dysfunction, and inflammation, and also improved the survival rate of mice following CLP operation. Additionally, MAPL deficiency or knockdown inhibited LPS-induced cardiomyocyte apoptosis, improved mitochondrial structural abnormalities, and increased ATP production. Furthermore, MAPL knockdown mitigated LPS-induced reductions in mitochondrial membrane potential (MMP) and intracellular reactive oxygen species (ROS) production. Mechanistically, the expression of dynamin-related protein 1 (drp1) in the mitochondria of heart tissues or H9C2 cardiomyocytes was elevated under septic conditions. Accordingly, the SUMOylation of drp1 in heart tissues or H9C2 cardiomyocytes was increased under sepsis conditions, which was reduced by MAPL knockout or knockdown., Conclusion: Our results reveal that MAPL promotes cardiac injury/dysfunction and inflammation in SCM. Deficiency or knockdown of MAPL alleviates SCM by reducing drp1 SUMOylation as well as drp1-mediated mitochondrial dysfunction. These findings suggest that targeting MAPL may represent a therapeutic strategy for patients with SCM., Competing Interests: Declarations Consent for publication All authors concur with the submission and publication of this paper. Conflict of interest The authors have no relevant financial or non-financial interests to disclose., (© 2024. The Author(s).)

The mitochondrial dynamic imbalance is an important cause of myocardial ischaemia/reperfusion (I/R) injury and dysfunction. Psmb8, as one of the immunoproteasome catalytic subunits, is a key regulator of protein homoeostasis, inflammation and some cardiac diseases. Here, we found that the expression level and activity of Psmb8 were significantly reduced in the heart of I/R mice and in subjects with myocardial infarction (MI). Cardiomyocyte-specific Psmb8 overexpression in mice markedly ameliorated I/R-mediated cardiac injury and dysfunction, which was accompanied by reduced mitochondrial division via the downregulation of dynamin-related protein-1 (Drp1). However, Psmb8 knockout (KO) mice exhibited the opposite changes. The effects of Psmb8 on mitochondrial fission and apoptosis was confirmed in primary cardiomyocytes with overexpression or knockdown of Psmb8 in vitro. Mechanistically, Psmb8 was directly associated with Drp1 and enhanced its degradation, which subsequently suppressed I/R-mediated mitochondrial fission and cardiac injury. Conversely, knockdown of Drp1 in Psmb8-KO mice restored I/R-induced cardiac dysfunction and mitochondrial dynamic imbalance. Our study identified a new cardioprotective role of Psmb8 in cardiac I/R damage through targeting Drp1, and highlight that increasing Psmb8 activity may constitute a promising therapy for ischaemic heart disease., (© 2024. The Author(s).)

Background: Latrophilin-2 (Lphn2), an adhesive GPCR (G protein-coupled receptor), was found to be a specific marker of cardiac progenitors during the differentiation of pluripotent stem cells into cardiomyocytes or during embryonic heart development in our previous studies. Its role in adult heart physiology, however, remains unclear., Methods: The embryonic lethality resulting from Lphn2 deletion necessitates the establishment of cardiomyocyte-specific, tamoxifen-inducible Lphn2 knockout mice, which was achieved by crossing Lphn2  flox/flox mice with mice having MerCreMer (tamoxifen-inducible Cre [Cyclization recombinase] recombinase) under the α-myosin heavy chain promoter., Results: Tamoxifen treatment for several days completely suppressed Lphn2 expression, specifically in the myocardium, and induced the dilated cardiomyopathy (D-CMP) phenotype with serious arrhythmia and sudden death in a short period of time. Transmission electron microscopy showed mitochondrial abnormalities, blurred Z-discs, and dehiscent myofibrils. The D-CMP phenotype, or heart failure, worsened during myocardial infarction. In a mechanistic study of D-CMP, Lphn2 knockout suppressed PGC-1α (Peroxisome proliferator-activated receptor gamma coactivator 1-alpha) and mitochondrial dysfunction, leading to the accumulation of reactive oxygen species and the global suppression of junctional molecules, such as N-cadherin (adherens junction), DSC-2 (desmocollin-2; desmosome), and connexin-43 (gap junction), leading to the dehiscence of cardiac myofibers and serious arrhythmia. In an experimental therapeutic trial, activators of p38-MAPK (p38 mitogen-activated protein kinases), which is a downstream signaling molecule of Lphn2, remarkably rescued the D-CMP phenotype of Lphn2 knockout in the heart by restoring PGC-1α and mitochondrial function and recovering global junctional proteins., Conclusions: Lphn2 is a critical regulator of heart integrity by controlling mitochondrial functions and cell-to-cell junctions in cardiomyocytes. Its deficiency leads to D-CMP, which can be rescued by activators of the p38-MAPK pathway., Competing Interests: None.

Cardiac cell damage frequently occurs as a consequence of acute myocardial infarction (AMI), a critical complication of coronary atherosclerotic heart disease. There is an escalating recognition of the association between COX2 and myocardial damage induced by ischemia. The objective of this study is to investigate the inhibitory effect of the COX2 on cardiomyocyte damage in the context of AMI. To create an AMI model, mice with the genetic background of wild-type C57BL6/J (WT) and COX2-/- mice were utilized. The left anterior descending (LAD) coronary artery in their hearts was obstructed, and subsequent assessment of hemodynamic parameters and heart function was conducted. Notably, increased levels of COX2 were observed in AMI mice. Through correlational analysis between COX2 expression and cardiac function following AMI, it was revealed that COX2 knockout mice had smaller infarct sizes, better cardiac performance, and suppressed levels of reactive oxygen species (ROS) compared to WT mice. Additionally, we discovered that COX2 knockout mice exhibited significantly higher mRNA levels of smooth muscle actin, collagen I, and collagen III than normal mice with AMI. Conversely, the levels of superoxide dismutase (SOD), malondialdehyde (MDA) were higher but iron content was decreased in COX2 knockout mice compared to normal mice with AMI.In summary, our research demonstrates that the downregulation of COX2 enhances cardiac tissue recovery in the context of AMI., (© 2024. The Author(s).)

Background: Although the exact role of mitophagy in the pathogenesis of diabetic cardiomyopathy (DCM) caused by type 2 diabetes mellitus (T2DM) remains controversial, recent studies revealed inhibition of mitophagy exacerbates cardiac injury in DCM. The zinc transporter ZIP7 has been reported to be upregulated by high glucose in cardiomyocytes and ZIP7 upregulation leads to inhibition of mitophagy in mouse hearts in the setting of ischemia/reperfusion. Nevertheless, little is known about the role of ZIP7 and its relationship with mitophagy in DCM caused by T2DM., Methods: T2DM was induced with high-fat diet (HFD) and streptozotocin. The cardiac-specific ZIP7 conditional knockout (ZIP7 cKO) mice were generated by adopting CRISPR/Cas9 system. Cardiac function was evaluated with echocardiography. Mitophagy was assessed by detecting mito-LC3II, mitoKeima, and mitoQC. Reactive oxygen species (ROS) were detected with DHE and mitoB., Results: ZIP7 was upregulated by T2DM in mouse hearts and ZIP7 cKO reduced mitochondrial ROS generation in mouse hearts with T2DM. Mitophagy was suppressed by T2DM in mouse hearts, which was prevented by ZIP7 cKO. T2DM inhibited PINK1 and Parkin accumulation in cardiac mitochondria, an effect that was prevented by ZIP7 cKO, pointing to that ZIP7 upregulation mediates T2DM-induced suppression of mitophagy by inhibiting the PINK1/Parkin pathway. T2DM induced mitochondrial hyperpolarization and decrease of mitochondrial Zn 2+ and this was blocked by ZIP7 cKO, indicating that upregulation of ZIP7 leads to mitochondrial hyperpolarization by reducing Zn 2+ within mitochondria. Finally, ZIP7 cKO prevented cardiac dysfunction and fibrosis caused by T2DM., Conclusions: ZIP7 upregulation mediates the inhibition of mitophagy by T2DM in mouse hearts by suppressing the PINK1/Parkin pathway. Reduction of mitochondrial Zn 2+ due to upregulation of ZIP7 accounts for the inhibition of the PINK1/Parkin pathway. Prevention of ZIP7 upregulation is essential for the treatment of T2DM-induced cardiomyopathy., (© 2024. The Author(s).)

Background: The proliferative capacity of cardiomyocytes in adult mammalian hearts is far too low to replace the cells that are lost to myocardial infarction. Both cardiomyocyte proliferation and myocardial regeneration can be improved via the overexpression of a constitutively active variant of YAP5SA (Yes-associated protein, 5SA [active] mutant), but persistent overexpression of proliferation-inducing genes could lead to hypertrophy and arrhythmia, whereas off-target expression in fibroblasts and macrophages could increase fibrosis and inflammation., Methods and Results: Transient overexpression of YAP5SA or GFP (green fluorescent protein; control) was targeted to cardiomyocytes via our cardiomyocyte-specific modified mRNA translation system ( YAP5SA CM-SMRTs or GFP CM-SMRTs, respectively). YAP5SA-cardiomyocyte specificity was confirmed via in vitro experiments in cardiomyocytes and cardiac fibroblasts that had been differentiated from human induced- pluripotent stem cells and in human umbilical-vein endothelial cells, and the regenerative potency of YAP5SA CM-SMRTs was evaluated in a mouse myocardial infarction model. In cultured human induced-pluripotent stem cells-cardiomyocytes, YAP was abundantly expressed for 3 days after YAP5SA CM-SMRTs administration and was accompanied by increases in the expression of markers for proliferation, before declining to near-background levels after day 7, whereas GFP fluorescence remained high from days 1 to 3 after GFP CM-SMRTs treatment and then slowly declined. GFP fluorescence was also observed in human induced-pluripotent stem cells-cardiac fibroblasts and human umbilical-vein endothelial cells on day 1 after GFP CM-SMRTs administration but declined substantially by day 3. In the mouse myocardial infarction model, echocardiographic assessments of left-ventricular ejection fraction and fractional shortening were significantly greater, whereas infarct sizes were significantly smaller in YAP5SA CM-SMRTs-treated mice than in vehicle-treated control animals, and YAP5SA CM-SMRTs appeared to promote cardiomyocyte proliferation., Conclusions: The CM-SMRTs can be used to transiently and specifically overexpress YAP5SA in cardiomyocytes, and this treatment strategy significantly promoted cardiomyocyte proliferation and myocardial regeneration in a mouse myocardial infarction model.

Sepsis is a systemic inflammatory response syndrome triggered by infection, presenting with symptoms such as fever, increased heart rate, and low blood pressure. In severe cases, it can lead to multiple organ dysfunction, posing a life-threatening risk. Sepsis-induced cardiomyopathy (SIC) is a critical factor in the poor prognosis of septic patients, leading to myocardial dysfunction characterized by cell death, inflammation, and diminished cardiac function. Ferroptosis, an iron-dependent form of programmed cell death, is a key mechanism causing cardiomyocyte damage in SIC. Growth differentiation factor 15 (GDF15), a member of the TGF-β superfamily, is associated with various cardiovascular diseases and can inhibit oxidative stress, reduce reactive oxygen species (ROS), and suppress ferroptosis. Elevated serum GDF15 levels in sepsis are correlated with organ injuries, suggesting its potential as a therapeutic target. However, its role and mechanisms in SIC remain unclear. Glutathione peroxidase 4 (GPX4), the only enzyme capable of reducing lipid peroxides within cells, protects cells by reducing lipid peroxidation levels and inhibiting ferroptosis. Investigating the regulatory factors of GPX4 may provide a theoretical basis for SIC treatment. In this study, a mouse SIC model revealed that elevated GDF15 exerts a protective effect. Antagonizing GDF15 exacerbates myocardial damage. Through transcriptomic analysis and other methods, we confirmed that GDF15 inhibits the expression of SOCS1 by activating the ALK5-SMAD2/3 pathway, thereby activates the JAK2/STAT3 pathway, promotes the transcription of GPX4, inhibits ferroptosis in cardiomyocytes, and plays a myocardial protective role in SIC., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Aims: Specific cavins and caveolins, known as caveola-related proteins, have been implicated in cardiac hypertrophy and myocardial injury. Cavin-2 forms complexes with other caveola-related proteins, but the role of Cavin-2 in cardiomyocytes (CMs) is poorly understood. Here, we investigated an unknown function of Cavin-2 in CMs., Methods and Results: Under cardiac stress-free conditions, systemic Cavin-2 knockout (KO) induced mild and significant CM hypertrophy. Cavin-2 KO suppressed phosphatase and tensin homologue (PTEN) associated with Akt signalling, whereas there was no difference in Akt activity between the hearts of the wild-type and the Cavin-2 KO mice under cardiac stress-free conditions. However, after swim training, CM hypertrophy was more facilitated with enhanced phosphoinositide 3-kinase (PI3K)-Akt activity in the hearts of Cavin-2 KO mice. Cavin-2 knockdown neonatal rat CMs (NRCMs) using adenovirus expressing Cavin-2 short hairpin RNA were hypertrophied and resistant to hypoxia and H2O2-induced apoptosis. Cavin-2 knockdown increased Akt phosphorylation in NRCMs, and an Akt inhibitor inhibited Cavin-2 knockdown-induced anti-apoptotic responses in a dose-dependent manner. Cavin-2 knockdown increased phosphatidylinositol-3,4,5-triphosphate production and attenuated PTEN at the membrane fraction of NRCMs. Immunostaining and immunoprecipitation showed that Cavin-2 was associated with PTEN at the plasma membrane of NRCMs. A protein stability assay showed that Cavin-2 knockdown promoted PTEN destabilization in NRCMs. In an Angiotensin II (2-week continuous infusion)-induced pathological cardiac hypertrophy model, CM hypertrophy and CM apoptosis were suppressed in CM-specific Cavin-2 conditional KO (Cavin-2 cKO) mice. Because Cavin-2 cKO mouse hearts showed increased Akt activity but not decreased extracellular signal-regulated kinase activity, suppression of pathological hypertrophy by Cavin-2 loss may be due to increased survival of healthy CMs., Conclusion: Cavin-2 plays a negative regulator in the PI3K-Akt signalling in CMs through interaction with PTEN. Loss of Cavin-2 enhances Akt activity by promoting PTEN destabilization, which promotes physiological CM hypertrophy and may enhance Akt-mediated cardioprotective effects against pathological CM hypertrophy., Competing Interests: Conflict of interest: none declared., (© The Author(s) 2024. Published by Oxford University Press on behalf of the European Society of Cardiology. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Background: Diabetic cardiomyopathy (DCM) is a serious complication in patients with type 2 diabetes mellitus, and its mechanisms are complex and poorly understood. Despite growing evidence suggesting that ferroptosis plays a significant role in cardiovascular disease, it has been less extensively studied in DCM. Fibroblast growth factor 21 (FGF21), whose mechanism of action is closely related to ferroptosis, is widely utilized in studies focused on the prevention and treatment of glucolipid metabolism-related diseases and cardiovascular diseases., Objective: To confirm the significant role of ferroptosis in DCM and to investigate whether FGF21 improves DCM by inhibiting ferroptosis and elucidating its specific molecular mechanisms., Methods: The animal DCM models were established through high-fat feeding combined with streptozotocin injection in C57BL/6J mice or by db/db mice, and the diabetic cardiomyocyte injury model was created using high glucose and high fat (HG/HF) culture of primary cardiomyocytes. Intervention modeling of FGF21 were performed by injecting adeno-associated virus 9-FGF21 in mice and transfecting FGF21 siRNA or overexpression plasmid in primary cardiomyocytes., Results: The findings indicated that ferroptosis was exacerbated and played a significant role in DCM. The overexpression of FGF21 inhibited ferroptosis and improved cardiac injury and function, whereas the knockdown of FGF21 aggravated ferroptosis and cardiac injury and function in DCM. Furthermore, we discovered that FGF21 inhibited ferroptosis in DCM by directly acting on ferritin and prolonging its half-life. Specifically, FGF21 binded to the heavy and light chains of ferritin, thereby reducing its excessive degradation in the proteasome and lysosomal-autophagy pathways in DCM. Additionally, activating transcription factor 4 (ATF4) served as the upstream regulator of FGF21 in DCM., Conclusions: The ATF4-FGF21-ferritin axis mediates the protective effects in DCM through the ferroptosis pathway and represents a potential therapeutic target for DCM., (© 2024. The Author(s).)

Background: Doxorubicin (DOX) is an effective anticancer drug, but it has a problem of cardiotoxicity that cannot be ignored. Ca 2+ /calmodulin-dependent protein kinase II (CaMKII) is tightly associated with the pathological progression of DOX-induced cardiotoxicity. Ubiquitin-specific protease 10 (USP10) plays an important role in many biological processes and cancers. However, its association with DOX-induced cardiotoxicity and CaMKII remains unclear., Methods: H9C2 cells, HL-1 cells and C57BL/6 mice were used to establish the DOX-induced cardiotoxicity model, and the CaMKII-specific inhibitor KN-93 and USP10 specific inhibitor Spautin-1 were used to observe the CaMKII and USP10 effect. In cell experiments, CCK-8 method was used to assess cell viability, LDH kit was used to assess lactate dehydrogenase expression, DCFH-DA staining was used to observe changes in active oxygen content, TUNEL staining was used to observe cell apoptosis, and Western blotting method was used to detect relevant protein markers. The expression of p-CaMKII and USP10 was assessed by immunofluorescence staining. In animal experiments, mouse echocardiograph was used were used to evaluate cardiac function, and HE staining and Masson staining were used to evaluate myocardial injury. Cardiomyocyte apoptosis was detected by TUNEL staining. Western blotting method was used to detect relevant protein markers., Results: Our results demonstrated that activation of CaMKII and inhibition of USP10 pathway related to DOX-induced cardiotoxicity. Inhibition of CaMKII with KN-93 ameliorated DOX-induced cardiac dysfunction and cytotoxicity. In addition, CaMKII inhibition prevented DOX-induced apoptosis and ubiquitination. Furthermore, CaMKII inhibition increased USP10 expression in DOX-treated mouse hearts, H9C2 cells and HL-1 cells. At last, the USP10 inhibitor, Spautin-1, blocked the regulatory effect of CaMKII inhibition on apoptosis and ubiquitination in DOX-induced cardiotoxicity., Conclusion: Our findings revealed that DOX-induced myocardial apoptosis and activated CaMKII through cellular and animal levels, while providing a novel probe into the mechanism of CaMKII action: promoting ubiquitination by inhibiting USP10 aggravated apoptosis., (© 2024 The Author(s). Cancer Medicine published by John Wiley & Sons Ltd.)

Alda-1 functions as an agonist of aldehyde dehydrogenase (ALDH2) within the mitochondria, contributing to the preservation of mitochondrial structure and function. This study aimed to determine whether Alda-1 inhibited the accumulation of mitochondrial reactive oxygen species (mtROS) and improved cardiomyocyte damage under oxidative stress. Cardiomyocytes derived from human induced pluripotent embryonic stem cells (iPSC-CMs) and human AC16 cardiomyocytes were chosen for the experiments. Oxidative stress was induced in both cardiomyocyte types using hydrogen peroxide (H 2 O 2 ), a commonly employed agent. The mtROS accumulation and mitochondrial functional status were assessed by measuring the ROS content, mitochondrial membrane potential, and mitochondrial respiratory chain function. Co-IP experiments were used to analyze whether mtROS promoted protein interactions between TXNIP and NLRP3 and induced NLRP3 inflammasome activation. The results showed that Alda-1 mitigated damage to mitochondrial structure and function under oxidative stress, concurrently reducing the accumulation of mtROS. Co-IP experiments revealed that elevated mtROS levels attenuated the protein interaction between TXNIP and TRX while intensifying the interaction between TXNIP and NLRP3. Consequently, this triggers activation of the NLRP3 inflammasome, leading to cardiomyocyte damage. In contrast, TXNIP knockdown inhibited H 2 O 2 -induced myocardial injury and enhanced the therapeutic effects of Alda-1. Collectively, the results show that, in an H 2 O 2 environment, Alda-1 increased the production of ALDH2 activity in cardiomyocytes, hindered the production of mtROS, disrupted the interaction between TXNIP and NLRP3, and alleviated myocardial damage during oxidative stress., (© 2024 Wiley Periodicals LLC.)

Background: Myotonic dystrophy type 1 (DM1) is a multiorgan disorder with significant cardiac involvement. ECG abnormalities, including arrhythmias, occur in 80 % of DM1 patients and are the second-most common cause of death after respiratory complications; however, the mechanisms underlying the arrhythmogenesis remain unclear. The objective of this study was to investigate the basis of the electrophysiological abnormalities in DM1 using the DMSXL mouse model., Methods: ECG parameters were evaluated at baseline and post flecainide challenge. Calcium transient and action potential parameters were evaluated in Langendorff-perfused hearts using fluorescence optical mapping. Calcium transient/sparks were evaluated in ventricular myocytes via confocal microscopy. Protein and mRNA levels for calcium handling proteins were evaluated using western blot and RT-qPCR, respectively., Results: DMSXL mice showed arrhythmic events on ECG including premature ventricular contractions and sinus block. DMSXL mice showed increased calcium transient time to peak without any change to voltage parameters. Calcium alternans and both sustained and non-sustained ventricular tachyarrhythmias were readily inducible in DMSXL mice. The confocal experiments also showed calcium transient alternans and increased frequency of calcium sparks in DMSXL cardiomyocytes. These calcium abnormalities were correlated with increased RyR2 phosphorylation without changes to the other calcium handling proteins., Conclusions: The DMSXL mouse model of DM1 exhibited enhanced arrhythmogenicity associated with abnormal intracellular calcium handling due to hyperphosphorylation of RyR2, pointing to RyR2 as a potential new therapeutic target in DM1 treatment., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

PCB126, a type of polychlorinated biphenyl (PCB), is a persistent pollutant found in both biotic and abiotic environments and poses significant public health risks due to its potential to cause cardiac damage with prolonged exposure. Hypoxia-inducible factor-2α (HIF-2α) is part of the hypoxia-inducible factor (HIF) transcription complex family. Previous studies have shown that knocking out or inhibiting HIF-2α expression can ameliorate pulmonary hypertension and right ventricular dysfunction. This study aimed to investigate whether cardiac-specific knockout of HIF-2α can alleviate the cardiotoxicity caused by PCB126. In this study, cardiac-specific knockout mice and wild-type mice were orally administered PCB126 or corn oil (50 μg/kg/week) for eight weeks. Our findings indicated that PCB126 induces cardiotoxicity and myocardial injury, as evidenced by elevated cardiac enzyme levels and increased cardiac collagen fibers. RNA sequencing revealed that PCB126-induced cardiotoxicity involves the PI3K/Akt and p53 signaling pathways, which was confirmed by western blot analysis. Notably, cardiac-specific knockout of HIF-2α mitigated the damage caused by PCB126, reducing the expression of cardiac enzymes, inflammatory cytokines, and myocardial collagen fibers. Under normal conditions, conditional knockout (CKO) of the HIF-2α gene in cardiomyocytes did not affect the morphology or function of the mouse heart. However, HIF-2α CKO in the heart reduced the cardiotoxic effects of PCB126 by decreasing apoptosis through the PI3K/Akt and p53 signaling pathways. In conclusion, inhibiting HIF-2α expression in cardiomyocytes attenuated PCB126-induced cardiotoxicity by modulating apoptosis through these signaling pathways., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

The purpose of this study was to investigate the mechanism of EMP1 action in high glucose (HG)-induced H9c2 cardiac cell pyroptosis and oxidative injury. Rat cardiomyocytes H9c2 were exposed to 33 mM glucose for 24, 48, or 72 h to induce cytotoxicity. EMP1-siRNA, NLRP3 agonist Nigericin, and pcNDA-RAS were used to treat H9c2 cells under HG conditions. Cell Counting Kit (CCK)-8 assay showed that cell proliferation was decreased following HG induction, which was rescued by EMP1 knockdown. Our results also suggested that EMP1 siRNA transfection significantly decreased the apoptosis and pyroptosis of HG-induced cells, as indicated by the reduction of NLRP3 IL-1β, ASC, GSDMD, cleaved-caspase1 and cleaved-caspase3 levels in HG-induced H9c2 cells. In addition, EMP1 knockdown alleviated HG-induced mitochondrial damage and oxidative stress in H9c2 cells. NLRP3 activation reversed the inhibitory effects of EMP1 knockdown on pyroptosis and oxidative stress in HG-induced H9c2 cells. Mechanistically, we found that EMP1 knockdown suppressed the RAS/RAF/MAPK signaling pathway in HG-induced H9c2 cells. RAS overexpression blocked the protective effect of EMP1 knockdown on HG-induced H9c2 cell apoptosis, pyroptosis, and oxidative injury. Our findings suggest that EMP1 knockdown treatment might provide a novel therapy for diabetic cardiomyopathy., (© 2024 Wiley Periodicals LLC.)

Background: A phase II clinical trial of metformin (MET) for the treatment of doxorubicin (DOX)-induced cardiotoxicity (NCT02472353) failed., Objectives: The aims of this study were to confirm MET-mediated protection against DOX-induced cardiotoxicity and its mechanism using H9C2 cells, and to establish a Wistar rat model of DOX-induced cardiotoxicity. Subsequently, Wistar rats were utilized to identify clinically relevant indicators for evaluating MET-mediated protection against DOX-induced cardiotoxicity, thereby facilitating early transition towards successful clinical trials., Methods: MET-mediated protection was assessed using cell viability and cytotoxicity experiments. Additionally, intramitochondrial reactive oxygen species (ROS) levels were measured using an ROS fluorescent probe (dihydroethidium) to confirm the oxidative stress mechanism. Eighteen Wistar rats were randomly allocated to the control, DOX, and DOX+MET groups; and the body weight, adverse drug reactions (ADRs), myocardial injury, cardiac function, oxidative stress, and histopathology of heart tissues were compared between groups., Results: H9C2 cells treated with MET/Dexrazoxane demonstrated dose-dependent protection against DOX-induced cardiotoxicity. The fluorescence intensity of H9C2 cells suggested DOX-induced cardiomyocyte toxicity and MET-mediated protection against DOX-induced cardiotoxicity. In vivo experiments confirmed that a rat model of DOX-induced cardiotoxicity was successfully established, but MET-mediated protection against DOX-induced cardiotoxicity was not demonstrated. This was attributed to insufficient energy intake because of ADRs, such as vomiting., Conclusions: We confirmed the MET-mediated protection against DOX-induced cardiomyocyte toxicity and its mechanism involving the inhibition of oxidative stress in vitro experiments. It is imperative to investigate the optimal conditions for MET-mediated protection against DOX-induced cardiotoxicity in vivo or clinical trials., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

Apoptosis is a crucial pathological process in myocardial ischemia/reperfusion injury (MIRI). Verapamil (Ver), normally used to treat hypertension or heart rhythm disorders, also attenuates MIRI. The potential of Ver to inhibit apoptosis and thereby attenuate MIRI remains unclear, as does the mechanism. We established an in vivo mouse ischemia/reperfusion (I/R) model by occlusion of the left anterior descending coronary. To construct a hypoxia/reoxygenation model in vitro, H9c2 cardiomyocytes were immersed in a hypoxic buffer in a hypoxia/anaerobic workstation. Ver significantly improved cardiac function and reduced myocardial infarction size in I/R mice, while decreasing apoptosis. Both in vivo and in vitro, application of Ver activated the JAK2/STAT3 signaling pathway and elevated Bcl-2 expression, while decreasing Bax and cleaved caspase-3 levels. Treatment with AG490, a JAK2 inhibitor, partially counteracted the anti-apoptotic and the cardioprotective effect of Ver. Thus, we conclude that Ver alleviates MIRI by reducing apoptosis via the JAK2/STAT3 signaling pathway activation. These findings provide a novel mechanism of Ver in the treatment of MIRI., Competing Interests: Declaration of Competing Interest The authors of this article declare that they have no known competing financial interests or personal relationships that could possibly influence the work reported in this article., (Copyright © 2024 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

Protein glycosylation is involved in DNA damage. Recently, DNA damage has been connected with the pathogenesis of heart failure. Cell adhesion associated, oncogene regulated (CDON), considered as an N-linked glycoprotein, is a transmembrane receptor for modulating cardiac function. But the role of CDON and its glycosylation in DNA damage remains unknown. In this study, we found that the knockdown of CDON caused DNA double-strand breaks as indicated by an increase in phosphorylated histone H2AX (γH2AX) protein level, immunofluorescent intensity of γH2AX and tail DNA moment in H9c2 cardiomyocytes. Conversely, overexpression of CDON led to decreasing DNA damage induced by hydrogen peroxide (H 2 O 2 ) and upregulating the expression of genes related to DNA repair pathways-homologous recombination (HR) and non-homologous end joining (NHEJ). Moreover, we expressed nine predicted N-glycosylation site mutants in H9c2 cells prior to treatment with H 2 O 2 . The results showed that mutation of N-glycosylation sites (N99Q, N179Q, and N870Q) increased the accumulation of DNA damage and downregulated the expression of HR-related genes, demonstrating that CDON N-glycosylation on DNA damage is site-specific and these specific N-glycan sites may regulate HR repair-related transcript abundance of genes. Our data highlight that N-glycosylation of CDON is critical to cardiomyocyte DNA lesion. It may uncover the potential strategies targeting DNA damage pathway in heart disease., Competing Interests: Declaration of Competing Interest All authors declare no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Background: C-type natriuretic peptide (CNP) is a significant player in the maintenance of cardiac and vascular homeostasis regulating local blood flow, platelet and leukocyte activation, heart structure and function, angiogenesis and metabolic balance. Since such processes are perturbed in myocardial infarction (MI), we explored the role of cardiomyocyte-derived CNP, and pharmacological administration of the peptide, in offsetting the pathological consequences of MI., Methods: Wild type (WT) and cardiomyocyte-restricted CNP null (cmCNP -/- ) mice were subjected to left anterior descending coronary artery (LADCA) ligation and acute effects on infarct size and longer-term outcomes of cardiac repair explored. Heart structure and function were assessed by combined echocardiographic and molecular analyses. Pharmacological administration of CNP (0.2 mg/kg/day; s.c.) was utilized to assess therapeutic potential., Results: Compared to WT littermates, cmCNP -/- mice had a modestly increased infarct size following LADCA ligation but without significant deterioration of cardiac structural and functional indices. However, cmCNP -/- animals exhibited overtly worse heart morphology and contractility 6 weeks following MI, with particularly deleterious reductions in left ventricular ejection fraction, dilatation, fibrosis and revascularization. This phenotype was largely recapitulated in animals with global deletion of natriuretic peptide receptor (NPR)-C (NPR-C -/- ). Pharmacological administration of CNP rescued the deleterious pathology in WT and cmCNP -/- , but not NPR-C -/- , animals., Conclusions and Implications: Cardiomyocytes synthesize and release CNP as an intrinsic protective mechanism in response to MI that reduces cardiac structural and functional deficits; these salutary actions are primarily NPR-C-dependent. Pharmacological targeting of CNP may represent a new therapeutic option for MI., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Adrian Hobbs reports financial support was provided by British Heart Foundation. Adrian Hobbs reports a relationship with Palatin Technologies Inc that includes: consulting or advisory. Adrian Hobbs reports a relationship with PharmaIN Corporation that includes: consulting or advisory. Adrian Hobbs reports a relationship with Novo Nordisk that includes: consulting or advisory. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Several studies have demonstrated that diabetes mellitus can increase the risk of cardiovascular disease and remains the principal cause of death in these patients. Costameres connect the sarcolemma with the cytoskeleton and extracellular matrix, facilitating the transmission of mechanical forces and cell signaling. They are related to cardiac physiology because individual cardiac cells are connected by intercalated discs that synchronize muscle contraction. Diabetes impacts the nanomechanical properties of cardiomyocytes, resulting in increased cellular and left ventricular stiffness, as evidenced in clinical studies of these patients. The question of whether costameric proteins are affected by diabetes in the heart has not been studied. This work analyzes whether type 1 diabetes mellitus (T1DM) modifies the costameric proteins and coincidentally changes the cellular mechanics in the same cardiomyocytes. The samples were analyzed by immunotechniques using laser confocal microscopy. Significant statistical differences were found in the spatial arrangement of the costameric proteins. However, these differences are not due to their expression. Atomic force microscopy was used to compare intrinsic cellular stiffness between diabetic and normal cardiomyocytes and obtain the first elasticity map sections of diabetic living cardiomyocytes. Data obtained demonstrated that diabetic cardiomyocytes had higher stiffness than control. The present work shows experimental evidence that intracellular changes related to cell-cell and cell-extracellular matrix communication occur, which could be related to cardiac pathogenic mechanisms. These changes could contribute to alterations in the mechanical and electrical properties of cardiomyocytes and, consequently, to diabetic cardiomyopathy. NEW & NOTEWORTHY The structural organization of cardiomyocyte proteins is critical for their efficient functioning as a contractile unit in the heart. This work shows that diabetes mellitus induces significant changes in the spatial organization of costamere proteins, t tubules, and intercalated discs. We obtained the first elasticity map sections of living diabetic cardiomyocytes. The results show statistical differences in the map sections of diabetic and control cardiomyocytes, with diabetic cardiomyocytes being stiffer than normal ones.

Thyroid hormone dysfunction is frequently observed in patients with chronic illnesses including heart failure, which increases the risk of adverse events. This study examined the effects of thyroid hormones (THs) on cardiac transverse-tubule (TT) integrity, Ca 2+ sparks, and nanoscale organization of ion channels in excitation-contraction (EC) coupling, including L-type calcium channel (Ca V 1.2), ryanodine receptor type 2 (RyR2), and junctophilin-2 (Jph2). TH deficiency was established in adult female rats by propyl-thiouracil (PTU) ingestion for 8 wk; followed by randomization to continued PTU without or with oral triiodo-l-thyronine (T3; 10 µg/kg/day) for an additional 2 wk (PTU + T3). Confocal microscopy of isolated cardiomyocytes (CMs) showed significant misalignment of TTs and increased Ca 2+ sparks in thyroid-deficient CMs. Density-based spatial clustering of applications with noise (DBSCAN) analysis of stochastic optical reconstruction microscopy (STORM) images showed decreased ( P < 0.0001) RyR2 cluster number per cell area in PTU CMs compared with euthyroid (EU) control myocytes, and this was normalized by T3 treatment. Ca V 1.2 channels and Jph2 localized within a 210 nm radius of the RyR2 clusters were significantly reduced in PTU myocytes, and these values were increased with T3 treatment. A significant percentage of the RyR2 clusters in the PTU myocytes had neither Ca V 1.2 nor Jph2, suggesting fewer functional clusters in EC coupling. Nearest neighbor distances between RyR2 clusters were greater ( P < 0.001) in PTU cells compared with EU- and T3-treated CMs that correspond to disarray of TTs at the sarcomere z -discs. These results support a regulatory role of T3 in the nanoscale organization of RyR2 clusters and colocalization of Ca V 1.2 and Jph2 in optimizing EC coupling. NEW & NOTEWORTHY Thyroid hormone (TH) dysfunction exacerbates preexisting heart conditions leading to an increased risk of premature morbidity/mortality. Triiodo-l-thyronine (T3) optimizes cardiac excitation-contraction (EC) coupling by maintaining myocardial T-tubule (TT) structures and organization of calcium ion channels. Single-molecule localization microscopy shows T3 effects on the clustering of ryanodine receptors (RyR2) with colocalization of L-type calcium channels (Ca V 1.2) and junctophilin-2 (Jph2) at TT-SR structures. Heart disease with subclinical hypothyroidism/low T3 syndrome may benefit from TH treatment.

Left ventricular hypertrophy (LVH) caused by chronic pressure overload with subsequent pathological remodeling is a major cardiovascular risk factor for heart failure and mortality. The role of deubiquitinases in LVH has not been well characterized. To define whether the deubiquitinase ubiquitin-specific peptidase 20 (USP20) regulates LVH, we subjected USP20 knockout (KO) and cognate wild-type (WT) mice to chronic pressure overload by transverse aortic constriction (TAC) and measured changes in cardiac function by serial echocardiography followed by histological and biochemical evaluations. USP20-KO mice showed severe deterioration of systolic function within 4 wk of TAC compared with WT cohorts. Both USP20-KO TAC and WT-TAC cohorts presented cardiac hypertrophy following pressure overload. However, USP20-KO-TAC mice showed an increase in cardiomyocyte length and developed maladaptive eccentric hypertrophy, a phenotype generally observed with volume overload states and decompensated heart failure. In contrast, WT-TAC mice displayed an increase in cardiomyocyte width, producing concentric remodeling that is characteristic of pressure overload. In addition, cardiomyocyte apoptosis, interstitial fibrosis, and mouse mortality were augmented in USP20-KO-TAC compared with WT-TAC mice. Quantitative mass spectrometry of LV tissue revealed that the expression of sarcomeric myosin heavy chain 7 (MYH7), a fetal gene normally upregulated during cardiac remodeling, was significantly reduced in USP20-KO after TAC. Mechanistically, we identified increased degradative lysine-48 polyubiquitination of MYH7 in USP20-KO hearts, indicating that USP20-mediated deubiquitination likely prevents protein degradation of MYH7 during pressure overload. Our findings suggest that USP20-dependent signaling pathways regulate the layering pattern of sarcomeres to suppress maladaptive remodeling during chronic pressure overload and prevent cardiac failure. NEW & NOTEWORTHY We identify ubiquitin-specific peptidase 20 (USP20) as an important enzyme that is required for cardiac homeostasis and function, particularly during myocardial pressure overload. USP20 regulates protein stability of cardiac MYH7, an essential molecular motor protein expressed in sarcomeres; loss-of-function mutations of MYH7 are associated with human hypertrophic cardiomyopathy, cardiac failure, and sudden death. Enhancing USP20 activity could be a potential therapeutic approach to prevent the development of maladaptive state of eccentric hypertrophy and heart failure.

Cardiac ischaemia/reperfusion (I/R) impairs mitochondrial function, resulting in excessive oxidative stress and cardiomyocyte ferroptosis and death. Nuclear factor E2-related factor 2 (Nrf2) is a key regulator of redox homeostasis and has cardioprotective effects against various stresses. Here, we tested whether CBR-470-1, a noncovalent Nrf2 activator, can protect against cardiomyocyte death caused by I/R stress. Compared with vehicle treatment, the administration of CBR-470-1 (2 mg/kg) to mice significantly increased Nrf2 protein levels and ameliorated the infarct size, the I/R-induced decrease in cardiac contractile performance, and the I/R-induced increases in cell apoptosis, ROS levels, and inflammation. Consistently, the beneficial effects of CBR-470-1 on cardiomyocytes were verified in a hypoxia/reoxygenation (H/R) model in vitro, but this cardioprotection was dramatically attenuated by the GPX4 inhibitor RSL3. Mechanistically, CBR-470-1 upregulated Nrf2 expression, which increased the expression levels of antioxidant enzymes (NQO1, SOD1, Prdx1, and Gclc) and antiferroptotic proteins (SLC7A11 and GPX4) and downregulated the protein expression of p53 and Nlrp3, leading to the inhibition of ROS production and inflammation and subsequent cardiomyocyte death (apoptosis, ferroptosis and pyroptosis). In summary, CBR-470-1 prevented I/R-mediated cardiac injury possibly through inhibiting cardiomyocyte apoptosis, ferroptosis and pyroptosis via Nrf2-mediated inhibition of p53 and Nlrp3 and activation of the SLC7A11/GPX4 pathway. Our data also highlight that CBR-470-1 may serve as a valuable agent for treating ischaemic heart disease., Competing Interests: Declaration of competing interest The authors declare that they have no conflicts of interest., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Fibrosis is the basis of structural remodeling in atrial fibrillation (AF), during which inflammation is crucial. Programmed cell death factor 4 (PDCD4) is a newly identified inflammatory gene, with unknown mechanisms of action in AF. The present study aimed to elucidate the effects of PDCD4 on the inflammation and structural remodeling of atrial myocytes. For this purpose, a PDCD4 overexpression plasmid (oePDCD4) and PDCD4 small interfering (si)RNA (siPDCD4) were used to modulate PDCD4 expression in mouse atrial myocytes (HL‑1 cells). The expression of PDCD4 was detected using reverse transcription‑quantitative PCR and western blot analysis. The optimal drug concentrations of peroxisome proliferator‑activated receptor γ (PPARγ) agonist (pioglitazone hydrochloride), NF‑κB inhibitor (CBL0137), PPARγ inhibitor (GW9962) and NF‑κB agonist (betulinic acid) were screened using a Cell Counting Kit‑8 assay. The levels of inflammatory factors were detected using enzyme‑linked immunosorbent assays, the expression levels of fibrosis‑related proteins and NF‑κB subunits were detected using western blot analysis, and the expression of phosphorylated (p‑)p65/p65 was detected using immunofluorescence staining. The results revealed that PDCD4 overexpression increased the levels of fibrotic factors (collagen I, collagen III, fibronectin, α‑smooth muscle actin and matrix metalloproteinase 2), pro‑inflammatory cytokines (IFN‑γ, IL‑6, IL‑17A and TNF‑α) and p‑p65, whereas it reduced the levels of anti‑inflammatory cytokines (IL‑4) in HL‑1 cells. Additionally, treatment with the PPARγ agonist and NF‑κB inhibitor reversed the levels of fibrotic‑, pro‑inflammatory and anti‑inflammatory factors in oePDCD4‑HL‑1 cells. By contrast, PDCD4 silencing exerted the opposite effects on fibrotic factors, pro‑inflammatory cytokines, anti‑inflammatory cytokines and p‑p65. In addition, treatment with the PPARγ inhibitor and NF‑κB agonist reversed the levels of fibrotic‑, pro‑inflammatory and anti‑inflammatory factors in siPDCD4‑HL‑1 cells. In conclusion, the present study demonstrated that PDCD4 may induce inflammation and fibrosis by activating the PPARγ/NF‑κB signaling pathway, thereby promoting the structural remodeling of atrial myocytes in AF.

Doxorubicin (Dox) has been limited in clinical application due to its cardiac toxicity that varies with the dose. This study aimed to explore how Rhein modulates Dox-induced myocardial toxicity. The general condition and echocardiographic changes of mice were observed to evaluate cardiac function and structure, with myocardial cell injury and apoptosis checked by TUNEL and HE staining. The ELISA assessed markers of myocardial damage and inflammation. The TCMSP and SwissTargetPrediction databases were used to retrieve Rhein's targets while GeneCards was used to find genes related to Dox-induced myocardial injury. Intersection genes were analyzed by Protein-Protein Interaction Networks. The core network genes underwent GO and KEGG enrichment analysis using R software. Western blot was used to detect protein expression. Compared to the Dox group, there was no remarkable difference in heart mass /body mass ratio in the Rhein+Dox group. However, heart mass/tibia length increased. Mice in the Rhein+Dox group had significantly increased LVEF, LVPWs, and LVFS compared to those in the Dox group. Myocardial cell damage, inflammation, and apoptosis significantly reduced in the Rhein+Dox group compared to the model group. Eleven core network genes were selected. Further, Rhein+Dox group showed significantly downregulated expression of p38/p-p38, HSP90AA1, c-Jun/p-c-Jun, c-Fos/p-c-Fos, Bax, and cleaved-caspase-3/caspase-3 while Bcl-2 expression significantly upregulated compared to the Dox group. The study suggests that Rhein mediates cardioprotection against Dox-induced myocardial injury, at least partly, by influencing multiple core genes in the MAPK signaling pathway to inhibit myocardial cell apoptosis., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

To uncover the possible role of TRAF3IP3 in the progression of myocardial infarction (MI), clarify its role in mitophagy and mitochondrial function, and explore the underlying mechanism. GEO chip analysis, RT-qPCR, and LDH release assay were used to detect the expression of TRAF3IP3 in tissues and cells and its effects on cell damage. Immunostaining and ATP product assays were performed to examine the effects of TRAF3IP3 on mitochondrial function. Co-IP, CHX assays, Immunoblot and Immunostaining assays were conducted to determine the effects of TRAF3IP3 on mitophagy. TRAF3IP3 was highly expressed in IR rats and HR-induced H9C2 cells. TRAF3IP3 knockdown can alleviate H/R-induced H9C2 cell damage. In addition, TRAF3IP3 knockdown can induce mitophagy, thus enhancing mitochondrial function. We further revealed that TRAF3IP3 can promote the degradation of NEDD4 protein. Moreover, TRAF3IP3 knockdown suppressed myocardial injury in I/R rats. TRAF3IP3 blocks mitophagy to exacerbate myocardial injury induced by I/R via mediating NEDD4 expression., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

The mitochondrial permeability transition (MPT) pore regulates necrotic cell death following diverse cardiac insults. While the componentry of the pore itself remains controversial, Cyclophilin D (CypD) has been well-established as a positive regulator of pore opening. We have previously identified Complement 1q-binding protein (C1qbp) as a novel CypD-interacting molecule and a negative regulator of MPT-dependent cell death in vitro. However, its effects on the MPT pore and sensitivity to cell death in the heart remain untested. We therefore hypothesized that C1qbp would inhibit MPT in cardiac mitochondria and protect cardiac myocytes against cell death in vivo. To investigate the effects of C1qbp in the myocardium we generated gain- and loss-of-function mice. Transgenic C1qbp overexpression resulted in decreased complex protein expression and reduced mitochondrial respiration and ATP production but MPT was unaffected. In contrast, while C1qbp +/- mice did not exhibit any changes in mitochondrial protein expression, respiration, or ATP, the MPT pore was markedly sensitized to Ca 2+ in these animals. Neither overexpression nor depletion of C1qbp significantly affected baseline heart morphology or function at 3 months of age. When subjected to myocardial infarction, C1qbp transgenic mice exhibited similar infarct sizes and cardiac remodeling to non-transgenic mice, consistent with the lack of an effect on MPT. In contrast, cardiac scar formation and dysfunction were significantly increased in the C1qbp +/- mice compared to C1qbp +/+ controls. Our results suggest that C1qbp is required for normal regulation of the MPT pore and mitochondrial function, and influences cardiac remodeling following MI, the latter more likely being independent of C1qbp effects on the MPT pore., Competing Interests: Declaration of competing interest None., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Chronic caloric restriction triggers unfavorable alterations in cardiac function albeit responsible scenarios remain unclear. This work evaluated the possible involvement of Akt2 in caloric restriction-evoked cardiac geometric and functional changes and responsible processes focusing on autophagy and mitophagy. Akt2 knockout and WT mice were subjected to caloric restriction for 30 weeks prior to assessment of myocardial homeostasis. Caloric restriction compromised echocardiographic parameters (decreased LV wall thickness, LVEDD, stroke volume, cardiac output, ejection fraction, fractional shortening, and LV mass), cardiomyocyte contractile and intracellular Ca 2+ capacity, myocardial atrophy, interstitial fibrosis and mitochondrial injury associated with elevated blood glucocorticoids, autophagy (LC3B, p62, Atg7, Beclin-1), and mitophagy (Pink1, Parkin, TOM20), dampened cardiac ATP levels, mitochondrial protein PGC1α and UCP2, anti-apoptotic protein Bcl2, intracellular Ca 2+ governing components Na + -Ca 2+ exchanger, phosphorylation of SERCA2a, mTOR (Ser 2481 ) and ULK1 (Ser 757 ), and upregulated Bax, phospholamban, phosphorylation of Akt2, AMPK, and ULK1 (Ser 555 ), the responses except autophagy markers (Beclin-1, Atg7), phosphorylation of AMPK, mTOR and ULK1 were negated by Akt2 ablation. Levels of CDK1 and DRP1 phosphorylation were overtly upregulated with caloric restriction, the response was reversed by Akt2 knockout. Caloric restriction-evoked changes in cardiac remodeling and cardiomyocyte function were alleviated by glucocorticoid receptor antagonism, Parkin ablation and Mdivi-1. In vitro experiment indicated that serum deprivation or glucocorticoids evoked GFP-LC3B accumulation and cardiomyocyte dysfunction, which was negated by inhibition of Akt2, CDK1 or DRP1, whereas mitophagy induction reversed Akt2 ablation-evoked cardioprotection. These observations favor a protective role of Akt2 ablation in sustained caloric restriction-evoked cardiac pathological changes via correction of glucocorticoid-induced mitophagy defect in a CDK1-DRP1-dependent manner., Competing Interests: Declaration of competing interest The authors have no competing financial interests to declare., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Fibronectin type III domain containing 4 (FNDC4) is highly homologous with FNDC5, which possesses various cardiometabolic protective functions. Emerging evidence suggests a noteworthy involvement of FNDC4 in fat metabolism and inflammatory processes. This study aimed to characterize the role of FNDC4 in myocardial ischemia/reperfusion (MI/R) injury and decrypt its underlying mechanisms. MI/R models of mice were established to investigate the alteration of FNDC4 in plasma and myocardium. We observed that plasma FNDC4 in MI/R-injury mice and patients experiencing acute myocardial infarction were both significantly reduced as opposed to their respective controls. Likewise, FNDC4 expression of myocardium decreased markedly in MI/R mice compared to the sham-operated group. Mice of FNDC4 knockout and myocardial overexpression were further introduced to elucidate the role of FNDC4 in MI/R injury by detecting cardiomyocyte apoptosis, myocardial infarct size, and cardiac function. Ablation of FNDC4 exacerbated cardiac dysfunction, increased myocardial infarction area and cardiomyocyte apoptosis when matched with wild-type mice post-MI/R. In contrast, FNDC4 overexpression through intramyocardial injection of rAAV9-Fndc4 significantly ameliorated cardiac function, reduced myocardial infarction area and cardiomyocyte apoptosis compared to sham group. Additionally, hypoxia-reoxygenation (H/R) was used to induce cardiomyocyte apoptosis, and to further elucidate the direct effects of FNDC4 on cardiomyocytes in vitro, and the results demonstrated that neonatal rat ventricular cardiomyocytes overexpressing FNDC4 showed less H/R-induced apoptosis, as evidenced by cleaved caspase 3 expression, TUNEL staining and flow cytometry. By performing RNA-seq analysis followed by cause-effect analysis, ERK1/2-Nrf2 pathway-mediated antioxidative effects were responsible for the protective roles of FNDC4 on cardiomyocytes. In summary, FNDC4 exerts cardioprotection against MI/R injury predominantly through mitigating oxidative stress responses and reducing cardiomyocyte apoptosis. These insights solidify the proposition of FNDC4 as a potential therapeutic aim for tackling MI/R damage., Competing Interests: Declaration of competing interest The authors have declared no conflict of interest., (Copyright © 2024. Published by Elsevier Inc.)

Doxorubicin-induced cardiotoxicity (DIC) poses a significant challenge, impeding its widespread application. Emerging evidence suggests the involvement of ferroptosis in the DIC. While the downregulation of SLC7A11 expression has been linked to the promotion of ferroptosis, the precise regulatory mechanism remains unclear. Recent studies, including our own, have highlighted abnormal levels of autophagy adapter protein P62 and autophagy in DIC development. Thus, our study aimed to further investigate the role of autophagy and ferroptosis in DIC, elucidating underlying molecular mechanisms across molecular, cellular, and whole-organ levels utilizing gene knockdown, immunoprecipitation, and mass spectrometry techniques. The results of our findings unveiled cardiomyocyte damage, heightened autophagy levels, and ferroptosis in DOX-treated mouse hearts. Notably, inhibition of autophagy levels attenuated DOX-induced ferroptosis. Mechanistically, we discovered that the autophagy adaptor protein P62 mediates the entry of SLC7A11 into the autophagic pathway for degradation. Furthermore, the addition of autophagy inhibitors (CQ or BAF) could elevate SLC7A11 and GPX4 protein expression, reduce the accumulation of Fe 2+ and ROS in cardiomyocytes, and thus mitigate DOX-induced ferroptosis. In summary, our findings underscore the pivotal role of the P62-autophagy pathway in SLC7A11 degradation, modulating ferroptosis to exacerbate DIC. This finding offers significant insights into the underlying molecular mechanisms of DOX-induced ferroptosis and identifies new targets for reversing DIC., Competing Interests: Declaration of competing interest All mouse experimental procedures were in accordance with the National Institutes of Health (NIH) Guide for the Care and Use of Laboratory Animals and approved by the Animal Care and Utilization Committee of Nanchang university. All authors agree to publish this manuscript without stating any relevant conflicts of interest. The authors did not use generative AI or AI-assisted technologies in the development of this manuscript. I hereby confirm that my submission contains a statement that fully and properly discloses any use of AI in the writing of this manuscript, as outlined., (Copyright © 2024 Elsevier Inc. All rights reserved.)

This research focused on investigating the effects of sevoflurane (Sev) on myocardial autophagy levels after myocardial ischemia reperfusion (I/R) injury via the microRNA-542-3p (miR-542-3p)/ADAM9 axis. Mice underwent 30 min occlusion of the left anterior descending coronary (LAD) followed by 2 h reperfusion. Cardiac infarction was determined by 2,3,5-triphenyltetrazolium chloride triazole (TTC) staining. Cardiac function was examined by echocardiography. Cardiac markers and oxidative stress factors were evaluated by ELISA. Autophagy-associated factors were detected by western blot. Relationship between miR-542-3p and ADAM9 was tested by dual-luciferase reporter gene assay, RT-qPCR, and western blot. Sev treatment ameliorated cardiac dysfunction, myocardial oxidative stress, and histopathological damages, decreased myocardial infarction size and myocardial apoptotic cells after myocardial I/R injury. Sev treatment elevated miR-542-3p expression and decreased ADAM9 expression in myocardial tissues after myocardial I/R injury. miR-542-3p overexpression could enhance the ameliorative effects of Sev on myocardial injury and myocardial autophagy in I/R mice. miR-542-3p targeted and negatively regulated ADAM9 expression. ADAM9 overexpression reversed the ameliorative effects of miR-542-3p up-regulation on myocardial injury and myocardial autophagy in Sev-treated I/R mice. Sev treatment could ameliorate myocardial injury and myocardial autophagy in I/R mice, mediated by mechanisms that include miR-542-3p up-regulation and ADAM9 down-regulation., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Hamartoma of mature cardiac myocytes (HMCM) is an extremely rare cardiac tumor characterized by benign growth of differentiated mature striated cardiac myocytes, and usually involves the ventricular myocardium. We describe the case of a 15-year-old female who presented with a short history of atrial fibrillation and a polypoid epicardial tumor that was attached to the interatrial groove by a short pedicle. The resected specimen showed features consistent with HMCM. Although these tumors are not associated with any known molecular or cytogenetic abnormalities, we identified fusions transcripts along with complex copy number anomalies of chromosome 7., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

In this study, by pooling the clinical data of patients who died with a history of long-term clozapine use and by examining their hearts, it was found that long-term clozapine use can lead to cardiomyopathy and that its presentation resembles arrhythmogenic cardiomyopathy (ACM), i.e., it exhibits a predominantly right ventricular fatty infiltration with mild left ventricular damage. The transcriptomic data of rat cardiomyocytes after clozapine intervention were analyzed by transcriptomic approach to explore the causes of clozapine cardiomyopathy. The cause of clozapine cardiomyopathy was then explored by a transcriptomic approach, which revealed that its clozapine action on cardiomyocytes enriched cardiomyocyte-related differential genes in biological processes such as muscle development and response to hypoxia, as well as pathways such as fatty acid metabolism and cellular autophagy. Transcriptomic analysis showed that Egr1, Egr2, ler2, Jun, Mapk9, Nr1d2, Atf3, Bhlhe40, Crem, Cry1, Cry2, Dbp were hub genes for clozapine injury to the myocardium, and that these genes may play an important role in the myocardial ACM-like changes caused by clozapine. Combined with the results of pathological examination and transcriptomic analysis, it can be concluded that the long-term action of clozapine on cardiomyocytes leads to cellular autophagy and subsequent structural remodeling of the heart, and in the remodeling affects fatty acid metabolism, which eventually leads to ACM-like changes., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Cardiac fibrosis occurs following insults to the myocardium and is characterized by the abnormal accumulation of non-compliant extracellular matrix (ECM), which compromises cardiomyocyte contractile activity and eventually leads to heart failure. This phenomenon is driven by the activation of cardiac fibroblasts (cFbs) to myofibroblasts and results in changes in ECM biochemical, structural and mechanical properties. The lack of predictive in vitro models of heart fibrosis has so far hampered the search for innovative treatments, as most of the cellular-based in vitro reductionist models do not take into account the leading role of ECM cues in driving the progression of the pathology. Here, we devised a single-step decellularization protocol to obtain and thoroughly characterize the biochemical and micro-mechanical properties of the ECM secreted by activated cFbs differentiated from human induced pluripotent stem cells (iPSCs). We activated iPSC-derived cFbs to the myofibroblast phenotype by tuning basic fibroblast growth factor (bFGF) and transforming growth factor beta 1 (TGF-β1) signalling and confirmed that activated cells acquired key features of myofibroblast phenotype, like SMAD2/3 nuclear shuttling, the formation of aligned alpha-smooth muscle actin (α-SMA)-rich stress fibres and increased focal adhesions (FAs) assembly. Next, we used Mass Spectrometry, nanoindentation, scanning electron and confocal microscopy to unveil the characteristic composition and the visco-elastic properties of the abundant, collagen-rich ECM deposited by cardiac myofibroblasts in vitro. Finally, we demonstrated that the fibrotic ECM activates mechanosensitive pathways in iPSC-derived cardiomyocytes, impacting on their shape, sarcomere assembly, phenotype, and calcium handling properties. We thus propose human bio-inspired decellularized matrices as animal-free, isogenic cardiomyocyte culture substrates recapitulating key pathophysiological changes occurring at the cellular level during cardiac fibrosis., Competing Interests: Declaration of competing interest Luca Bersanini and Malin Becker are employees of Optics11 Life B.V., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Environmental antineoplastics such as sorafenib may pose a risk to humans through water recycling, and the increased risk of cardiotoxicity is a clinical issue in sorafenib users. Thus, developing strategies to prevent sorafenib cardiotoxicity is an urgent work. Empagliflozin, as a sodium-glucose co-transporter-2 (SGLT2) inhibitor for type 2 diabetes control, has been approved for heart failure therapy. Still, its cardioprotective effect in the experimental model of sorafenib cardiotoxicity has not yet been reported. Real-time quantitative RT-PCR (qRT-PCR), immunoblot, and immunohistochemical analyses were applied to study the effect of sorafenib exposure on cardiac SGLT2 expression. The impact of empagliflozin on cell viability was investigated in the sorafenib-treated cardiomyocytes using Alamar blue assay. Immunoblot analysis was employed to delineate the effect of sorafenib and empagliflozin on ferroptosis/proinflammatory signaling in cardiomyocytes. Ferroptosis/DNA damage/fibrosis/inflammation of myocardial tissues was studied in mice with a 28-day sorafenib ± empagliflozin treatment using histological analyses. Sorafenib exposure significantly promoted SGLT2 upregulation in cardiomyocytes and mouse hearts. Empagliflozin treatment significantly attenuated the sorafenib-induced cytotoxicity/DNA damage/fibrosis in cardiomyocytes and mouse hearts. Moreover, GPX4/xCT-dependent ferroptosis as an inducer for releasing high mobility group box 1 (HMGB1) was also blocked by empagliflozin administration in the sorafenib-treated cardiomyocytes and myocardial tissues. Furthermore, empagliflozin treatment significantly inhibited the sorafenib-promoted NFκB/HMGB1 axis in cardiomyocytes and myocardial tissues, and sorafenib-stimulated proinflammatory signaling (TNF-α/IL-1β/IL-6) was repressed by empagliflozin administration. Finally, empagliflozin treatment significantly attenuated the sorafenib-promoted macrophage recruitments in mouse hearts. In conclusion, empagliflozin may act as a cardioprotective agent for humans under sorafenib exposure by modulating ferroptosis/DNA damage/fibrosis/inflammation. However, further clinical evidence is required to support this preclinical finding., (© 2024 Wiley Periodicals LLC.)

Doxorubicin (DOX) is restricted due to its severe cardiotoxicity. There is still a lack of viable and effective drugs to prevent or treat DOX-induced cardiotoxicity(DIC). Vericiguat is widely used to treat heart failure with reduced ejection fraction. However, it is not clear whether vericiguat can improve DIC. In the present study, we constructed a DIC model using mice and neonatal rat cardiomyocytes and found that vericiguat ameliorated DOX-induced cardiac insufficiency in mice, restored DOX-induced mitochondrial dysfunction in neonatal rat cardiomyocytes, and inhibited the expression of inflammatory factors. Further studies showed that vericiguat improved mitochondrial dysfunction and reduced mtDNA leakage into the cytoplasm by up-regulating PRKG1, which activated PINK1 and then inhibited the STING/IRF3 pathway to alleviate DIC. These findings demonstrate for the first time that vericiguat has therapeutic potential for the treatment of DIC., Competing Interests: Declaration of competing interest There are no conflicts to declare., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Accumulation studies confirmed that oxidative stress caused by ischemia after myocardial infarction (MI) is an important cause of ventricular remodeling. Exosome secretion through hypoxic pretreatment adipose-derived mesenchymal stem cells (ADSCs) ameliorates myocardial damaging post-MI. However, if ADSCs exosome can improve the microenvironment and ameliorate cardiac damage post-MI still unknown. Next-generation sequencing (NGS) was used to study abnormally expressed circRNAs in hypoxic pretreatment ADSC exosomes (HExos) and untreated ADSC exosomes (Exos). Bioinformatics and luciferase reporting were used to elucidate interaction correlation related to circRNA, mRNA, and miRNA. HL-1 cells were used to analyze the reactive oxygen species (ROS) and apoptosis under hypoxic conditions using immunofluorescence and flow cytometry. An MI mouse model was constructed and the therapeutic effect of Exos was determined using immunohistochemistry, immunofluorescence, and ELISA. The results showed that HExos had a more pronounced treatment effect than ADSC Exos on cardiac damage amelioration after MI. NGS showed that circ-Stt3b plays a role in HExo-mediated cardiac damage repair after MI. Overexpression of circ-Stt3b decreased apoptosis, ROS level, and inflammatory factor expression in HL-1 cells under hypoxic conditions. Bioinformatics and luciferase reporting data validated miR-15a-5p and GPX4 as downstream circ-Stt3b targets. GPX4 downregulation or miR-15a-5p overexpression reversed protective effect regarding circ-Stt3b upon HL-1 cells after exposure to a hypoxic microenvironment. Overexpression of circ-Stt3b increased the treatment effect of ASDSC Exos on cardiac damage amelioration after MI. Taken together, the study results demonstrated that Exos from hypoxic pretreatment ADSCs ameliorate cardiac damage post-MI through circ-Stt3b/miR-15a-5p/GPX4 signaling activation and decreased ferroptosis., (© 2024. The Author(s).)

Abstract: Heart failure has always been a prevalent, disabling, and potentially life-threatening disease. For the treatment of heart failure, controlling cardiac remodeling is very important. In recent years, clinical trials have shown that sodium-glucose cotransporter-2 (SGLT-2) inhibitors not only excel in lowering glucose levels but also demonstrate favorable cardiovascular protective effects. However, the precise mechanisms behind the cardiovascular benefits of SGLT-2 inhibitors remain elusive. In this research, we assessed the impact of canagliflozin (CANA, an SGLT-2 inhibitor) on cardiac remodeling progression in mice and preliminarily elucidated the possible mechanism of action of the SGLT-2 inhibitor. Our results indicate that the administration of canagliflozin significantly attenuates myocardial hypertrophy and fibrosis and enhances cardiac ejection function in mice with isoprenaline (ISO)-induced cardiac remodeling. Notably, excessive mitophagy, along with mitochondrial structural abnormalities observed in ISO-induced cardiac remodeling, was mitigated by canagliflozin treatment, thereby attenuating cardiac remodeling progression. Furthermore, the differential expression of AMPK/PINK1/Parkin pathway-related proteins in ISO-induced cardiac remodeling was effectively reversed by canagliflozin, suggesting the therapeutic potential of targeting this pathway with the drug. Thus, our study indicates that canagliflozin holds promise in mitigating cardiac injury, enhancing cardiac function, and potentially exerting cardioprotective effects by modulating mitochondrial function and mitophagy through the AMPK/PINK1/Parkin pathway., Competing Interests: The authors report no conflicts of interest., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Myocardial infarctions locally deprive myocardium of oxygenated blood and cause immediate cardiac myocyte necrosis. Irreparable myocardium is then replaced with a scar through a dynamic repair process that is an interplay between hypoxic cells of the infarct zone and normoxic cells of adjacent healthy myocardium. In many cases, unresolved inflammation or fibrosis occurs for reasons that are incompletely understood, increasing the risk of heart failure. Crosstalk between hypoxic and normoxic cardiac cells is hypothesized to regulate mechanisms of repair after a myocardial infarction. To test this hypothesis, microfluidic devices are fabricated on 3D printed templates for co-culturing hypoxic and normoxic cardiac cells. This system demonstrates that hypoxia drives human cardiac fibroblasts toward glycolysis and a pro-fibrotic phenotype, similar to the anti-inflammatory phase of wound healing. Co-culture with normoxic fibroblasts uniquely upregulates pro-inflammatory signaling in hypoxic fibroblasts, including increased secretion of tumor necrosis factor alpha (TNF-α). In co-culture with hypoxic fibroblasts, normoxic human induced pluripotent stem cell (hiPSC)-derived cardiac myocytes also increase pro-inflammatory signaling, including upregulation of interleukin 6 (IL-6) family signaling pathway and increased expression of IL-6 receptor. Together, these data suggest that crosstalk between hypoxic fibroblasts and normoxic cardiac cells uniquely activates phenotypes that resemble the initial pro-inflammatory phase of post-infarct wound healing., (© 2024 Wiley‐VCH GmbH.)

Dapagliflozin (DAPA), a sodium-glucose cotransporter 2 (SGLT2) inhibitor, is well-recognized for its therapeutic benefits in type 2 diabetes (T2D) and cardiovascular diseases. In this comprehensive in vitro study, we investigated DAPA's effects on cardiomyocytes, aortic endothelial cells (AECs), and stem cell-derived beta cells (SC-β), focusing on its impact on hypertrophy, inflammation, and cellular stress. Our results demonstrate that DAPA effectively attenuates isoproterenol (ISO)-induced hypertrophy in cardiomyocytes, reducing cell size and improving cellular structure. Mechanistically, DAPA mitigates reactive oxygen species (ROS) production and inflammation by activating the AKT pathway, which influences downstream markers of fibrosis, hypertrophy, and inflammation. Additionally, DAPA's modulation of SGLT2, the Na+/H + exchanger 1 (NHE1), and glucose transporter (GLUT 1) type 1 highlights its critical role in maintaining cellular ion balance and glucose metabolism, providing insights into its cardioprotective mechanisms. In aortic endothelial cells (AECs), DAPA exhibited notable anti-inflammatory properties by restoring AKT and phosphoinositide 3-kinase (PI3K) expression, enhancing mitogen-activated protein kinase (MAPK) activation, and downregulating inflammatory cytokines at both the gene and protein levels. Furthermore, DAPA alleviated tumor necrosis factor (TNFα)-induced inflammation and stress responses while enhancing endothelial nitric oxide synthase (eNOS) expression, suggesting its potential to preserve vascular function and improve endothelial health. Investigating SC-β cells, we found that DAPA enhances insulin functionality without altering cell identity, indicating potential benefits for diabetes management. DAPA also upregulated MAFA, PI3K, and NRF2 expression, positively influencing β-cell function and stress response. Additionally, it attenuated NLRP3 activation in inflammation and reduced NHE1 and glucose-regulated protein GRP78 expression, offering novel insights into its anti-inflammatory and stress-modulating effects. Overall, our findings elucidate the multifaceted therapeutic potential of DAPA across various cellular models, emphasizing its role in mitigating hypertrophy, inflammation, and cellular stress through the activation of the AKT pathway and other signaling cascades. These mechanisms may not only contribute to enhanced cardiac and endothelial function but also underscore DAPA's potential to address metabolic dysregulation in T2D., (© 2024. The Author(s).)