Myocardial infarction (MI) remains the leading cause of death due to cardiovascular disease worldwide. role of MYZAP in angiogenesis remains unclear. The expression of MYZAP in MI was significantly decreased. Endothelial-specific overexpression of MYZAP improved cardiac function, increased angiogenesis, and restored hindlimb blood flow levels in MI mice detected by MoorFLPIReview. The proliferation ability, migration, and invasion of endothelial cells were reduced after hypoxia, which were restored after overexpression of MYZAP or knockdown of RND1. The pro-angiogenic effect of MYZAP overexpression was reversed by RND1 overexpression. The proliferation ability, migration and invasion ability, and tube formation ability of endothelial cells were significantly reduced after knockdown of MYZAP. Direct interaction between MYZAP and RND1 was confirmed by co-immunoprecipitation (Co-IP) and thermal stability assays. TRIM21 was identified as a potential E3 ubiquitin ligase responsible for RND1 degradation. Our work revealed that endothelial-specific overexpression of MYZAP enhances angiogenesis by activating the VEGF/PI3K/AKT pathway in MI.

Myocardial infarction (MI) stands as a leading contributor to global cardiovascular morbidity and mortality, defined by ischemic myocardial cell death and subsequent impairment of cardiac function. The tripartite motif (TRIM) protein family has been shown to regulate myocardial ischemia-reperfusion injury. As a key member of the TRIM protein family, tripartite motif-containing protein 28 (TRIM28) exhibits dysregulated expression in the heart during MI yet its pathophysiological role remains to be fully elucidated. This study aimed to investigate the functional roles and underlying mechanisms of TRIM28 in MI. We observed a significant upregulation of TRIM28 in ischemic myocardium and hypoxic cardiomyocytes. Genetic knockout of TRIM28 ameliorated cardiac function and attenuated apoptosis in MI mice, whereas its overexpression exacerbated contractile dysfunction, and promoted cardiomyocyte apoptosis and mitochondrial injury. Mechanistically, TRIM28 directly interacts with activating transcription factor 5 (ATF5) and suppresses its SUMOylation, thereby enhancing the ubiquitin-mediated degradation of ATF5, inhibiting the mitochondrial unfolded protein response (UPRmt), and ultimately culminating in increased apoptosis. Via molecular docking, we identified a TRIM28-targeting compound, Oolonghomobisflavan B (OFB), which attenuated post-MI apoptosis and facilitated cardiac function recovery. Collectively, these findings demonstrate that TRIM28 acts as a critical regulator of MI progression, and OFB holds therapeutic potential as a candidate drug.

Cardiac aging is associated with progressive cardiac fibrosis and dysfunction, yet the underlying mechanisms remain incompletely understood. Extrachromosomal circular DNA (eccDNA) has been reported to participate in tumor and age-related genomic instability, while its role in cardiac fibrosis during aging remains to be fully elucidated. In this study, circular DNA sequencing and RNA seqencing were performed to analyze eccDNA profiles in young and aged cardiac tissues. The number of eccDNAs in the cardiac tissue of aged mice is higher than that in young mice. Combining the annotation of eccDNAs and the key genes related to aging identified in the transcriptome, we identified sterile alpha and TIR motif containing 1 (Sarm1), a key regulator of NAD+ metabolism and neurodegeneration located in eccDNAs, as a novel driver of cardiac aging via pro-fibrotic signaling. In aged mice, Sarm1 knockdown significantly restored cardiac function and reduced fibrosis. Conversely, Sarm1 accelerated cardiac aging phenotypes in young Sarm1-overexpressing transgenic mice. Mechanistically, co-immunoprecipitation combined with mass spectrometry identified TGF-β-Smad2/3 as the dominant pathway, with pharmacological inhibition by SIS3 abolishing Sarm1-driven Smad2/3 phosphorylation. Our findings reveal that Sarm1-containing eccDNA drives cardiac aging by amplifying pro-fibrotic signaling through the TGF-β-Smad2/3 pathway, proposing eccDNAs clearance and Sarm1 inhibition as novel therapeutic strategies for aging-related cardiac fibrosis.

Stem cell therapies are emerging as promising strategies for repair after myocardial infarction (MI), but the repair efficacy is limited by the poor cardiac microenvironment represented by the inflammatory response, as well as oxidative stress, and adverse electrical coupling. Here, we developed an injectable supramolecular hydrogel (HCPA) that modulates the infarct microenvironment and accelerates myocardial repair by encapsulating human induced pluripotent stem cells derived cardiomyocytes (hiPSC-CMs). HCPA hydrogel not only exhibited excellent reactive oxygen species (ROS) response in order to minimize oxidative stress but also possessed desirable electrical conductivity for the reintegration of electrical impulses. Critically, RNA sequencing demonstrated that the PPARα/NFκB pathway contributed significantly to the HCPA hydrogel-promoted macrophage polarization from M1-type to M2-type, thus alleviating inflammatory responses. HCPA hydrogel harboring hiPSC-CMs increased retention of hiPSC-CMs and improved cardiac function in MI mice. This study represents a new integrated therapeutic option for MI and provides insights for the development of novel biomaterials in the field of tissue engineering.

Cardiac ischemia‒reperfusion (I/R) injury is a leading cause of disability and mortality worldwide, but the underlying mechanism remains largely unknown. Despite the emerging recognition of circular RNAs (circRNAs) as pivotal regulators of cardiac development and disease, their roles in cardiac I/R injury have yet to be thoroughly investigated. In this study, we identified a circRNA named circArhgap26, which is regulated by m6A modification. The expression of circArhgap26 was significantly decreased in the I/R myocardium. Cardiac-specific overexpression of circArhgap26 ameliorated cardiac dysfunction and reduced the infarct area and cardiomyocyte apoptosis in I/R model mice. Mechanistically, circArhgap26 directly bound to PKP1, thereby inhibiting the interaction between PKP1 and the palmitoyltransferase ZDHHC1. The subsequent palmitoylation of PKP1 and its protein stability are subsequently diminished, leading to a reduction in APAF1 protein synthesis and the inhibition of the Caspase-9/Caspase-3 signaling pathway, thereby mitigating cardiomyocyte apoptosis. Most importantly, the expression of circArhgap26 in the plasma of patients undergoing percutaneous coronary intervention (PCI) was decreased. This study not only elucidates the dual regulatory mechanisms of circArhgap26, m6A modification and posttranslational modification (palmitoylation), in combating I/R injury but also provides a theoretical foundation for circRNA-based therapies. Its dual value as a prognostic biomarker and therapeutic target holds promise for advancing precision cardiovascular medicine and improving outcomes in globally prevalent I/R-related diseases.

Dystrophin is a critical interacting protein of Nav1.5 that determines its membrane anchoring in cardiomyocytes. Long noncoding RNAs (lncRNAs) are involved in the regulation of cardiac ion channels, while their influence on sodium channel remains unexplored. Our preliminary data showed that lncRNA-Dachshund homolog 1 (lncDACH1) can bind to dystrophin, which drove us to investigate if lncDACH1 can regulate sodium channel by interfering with dystrophin. Western blot and immunofluorescent staining showed that cardiomyocyte-specific transgenic overexpression of lncDACH1(lncDACH1-TG) reduced the membrane distribution of dystrophin and Nav1.5 in cardiomyocytes. Meanwhile, peak I Na were reduced in the hearts of lncDACH1-TG mice than wild-type (WT) controls. The opposite data of western blot ,immunofluorescent staining and patch clamp were collected from lncDACH1 cardiomyocyte conditional knockout (lncDACH1-cKO) mice. Moreover, increased ventricular arrhythmia susceptibility was observed in lncDACH1-TG mice in vivo and ex vivo . The conservative fragment of lncDACH1 inhibited membrane distribution of dystrophin and Nav1.5, and promoted the inducibility of ventricular arrhythmia. Strikingly, activation of dystrophin transcription by dCas9-SAM system in lncDACH1-TG mice rescued the impaired membrane distribution of dystrophin and Nav1.5, and prevented the occurrence of ventricular arrhythmia. Furthermore, lncDACH1 was increased in transaortic constriction (TAC) induced failing hearts, which promoted the inducibility of ventricular arrhythmia. And the expression of lncDACH1 is regulated by hydroxyacyl-CoA dehydrogenase subunit beta (hadhb), which binds to lncDACH1 and decreases its stability. The human homologue of lncDACH1 inhibited the membrane distribution of Nav1.5 in human iPS-differentiated cardiomyocytes. The findings provide novel insights into the mechanism of Nav1.5 membrane targeting and the development of ventricular arrhythmias.

Myocardial infarction (MI) is characterized by focal necrosis resulting from prolonged myocardial ischemia due to coronary artery obstruction. Vascular reconstruction following MI is crucial for improving cardiac function and preventing recurrent infarction. This study investigates the interaction between macrophages and endothelial cells in angiogenesis mediated by nicotinamide mononucleotide (NMN)-induced secretion of macrophage-derived exosomes. We focus on the role of U2 small nuclear RNA auxiliary factor 1 (U2af1) gene, a member of the splicing factor serine and arginine (SR) gene family, in the regulation of angiogenesis. Through cardiac ultrasound, Masson staining, 2,3,5-triphenyltetrazolium chloride (TTC) staining, Microfil vascular perfusion, and platelet and endothelial cell adhesion molecule 1 (CD31) immunofluorescence staining, extracellular vesicles from NMN-stimulated macrophages were shown to exert a protective effect in MI, with proteomic analysis identifying U2AF1 as a candidate protein involved in MI protection. Plasma U2AF1 levels were measured in 70 MI patients, revealing significantly lower levels in individuals with poor coronary collateral vessel (CCV; Rentrop scores 0–1) than in those with good CCV (Rentrop scores 2–3). In both myocardial and hindlimb ischemia mouse models, overexpression of endothelial cell-specific adenoviral overexpression U2AF1 promoted angiogenesis in the heart and hindlimbs and improved cardiac function after MI. Mechanistic studies demonstrated that U2AF1 regulates the alternative splicing (AS) of Yes1-associated transcriptional regulator (Yap1) gene, influencing post-MI angiogenesis and cardiac function recovery. Collectively, our clinical findings suggest that U2AF1 may serve as a therapeutic target for coronary collateral angiogenesis following MI. Given the low immunogenicity and high biosafety of exosomes, this study provides a foundational basis and translational potential for exosome-based therapies in MI treatment.

Myocardial fibrosis is a serious cause of heart failure and even sudden cardiac death. However, the mechanisms underlying myocardial ischemia-induced cardiac fibrosis remain unclear. Here, we identified that the expression of sterile alpha and TIR motif containing 1 (SARM1), was increased significantly in the ischemic cardiomyopathy patients, dilated cardiomyopathy patients (GSE116250) and fibrotic heart tissues of mice. Additionally, inhibition or knockdown of SARM1 can improve myocardial fibrosis and cardiac function of myocardial infarction (MI) mice. Moreover, SARM1 fibroblasts-specific knock-in mice had increased deposition of extracellular matrix and impaired cardiac function. Mechanically, elevated expression of SARM1 promotes the deposition of extracellular matrix by directly modulating P4HA1. Notably, by using the Click-iT reaction, we identified that the increased expression of ZDHHC17 promotes the palmitoylation levels of SARM1, thereby accelerating the fibrosis process. Based on the fibrosis-promoting effect of SARM1, we screened several drugs with anti-myocardial fibrosis activity. In conclusion, we have unveiled that palmitoylated SARM1 targeting P4HA1 promotes collagen deposition and myocardial fibrosis. Inhibition of SARM1 is a potential strategy for the treatment of myocardial fibrosis. The sites where SARM1 interacts with P4HA1 and the palmitoylation modification sites of SARM1 may be the active targets for anti-fibrosis drugs.

Background:Effective inhibition of pathological cardiac hypertrophy is critical for managing various cardiovascular diseases,especially in cold environments.The communication between cardiomyocytes and fibroblasts,mediated by secreted proteins,plays a significant role in the development and progression of pathological cardiac hypertrophy.Serpin Family E Member 2(serpinE2),secreted by fibroblasts into the extracellular space,has been implicated in this process.However,whether serpinE2 can be internalized by cardiomyocytes and whether cold exposure influences this process remains unclear.Materials and methods:Mice were subjected to cold exposure(4 ℃,12 h/day for 8 weeks),and cardiac hypertrophy was induced by transverse aortic constriction(TAC).SerpinE2 expression was silenced by short interfering RNA(siRNA).Cardiac fibroblasts were stimulated with angiotensin Ⅱ(Ang Ⅱ)to induce serpinE2 secretion.Exogenous recombinant serpinE2,labeled with DyLight 488 or His-tag,was used to evaluate its internalization and functional role in cardiomyocytes.Internalization was inhibited by using antibodies against serpinE2,heparin,or endocytosis inhibitors(β-cyclodextrin,nystatin,dynasore,and chlorpromazine).Chromatin immunoprecipitation followed by quantitative polymerase chain reaction(PCR)was used to assess the binding of the transcription factor CDX1 to the serpinE2 promoter.Results:Cold exposure significantly increased serpinE2 mRNA and protein expression in mouse hearts.SerpinE2 levels were also upregulated in plasma and cardiac tissue following TAC.Knockdown of serpinE2 attenuated TAC-induced hypertrophy,restored left ventricular function,and reduced atrial natriuretic peptide,brain natriuretic peptide,and β-myosin heavy chain fragment levels.Exogenous serpinE2 promoted cardiomyocyte hypertrophy,an effect that was reversed by serpinE2 knockdown.Co-culture with conditioned medium from Ang Ⅱ-stimulated fibroblasts increased serpinE2 expression in cardiomyocytes.Exogenous serpinE2 was internalized via endocytosis,which was inhibited by antibodies,heparin,and endocytosis blockers.Internalized serpinE2 activated the protein kinase B(AKT)/β-catenin pathway in cardiomyocytes.CDX1 bound to the serpinE2 promoter and promoted its transcription in fibroblasts.CDX1 overexpression increased serpinE2 and collagen expression,while its suppression had the opposite effect.Administration of exogenous fibroblast growth factor 4(FGF4)or overexpression of FGF4 plasmid upregulated CDX1,serpinE2,and collagen expression in fibroblasts.Conclusions:SerpinE2 expression is responsive to cold stress and mediates intercellular communication between fibroblasts and cardiomyocytes.Fibroblast-secreted serpinE2 is internalized by cardiomyocytes via endocytosis,promoting hypertrophy through activation of the phosphatidylinositol 3-kinase(PI3K)-AKT/β-catenin pathway.The FGF4-CDX1 axis regulates serpinE2 expression and secretion in cardiac fibroblasts.

Myocardial ischemia/reperfusion (IR) injury is a common adverse event in the clinical treatment of myocardial ischemic disease. Autosis is a form of cell death that occurs when autophagy is excessive in cells, and it has been associated with cardiac IR damage. This study aimed to investigate the regulatory mechanism of circRNA CDR1AS on autosis in cardiomyocytes under IR. The expression of CDR1AS increases after myocardial IR, and overexpression of CDR1AS detrimentally affects cardiac function, increases infarct area, promotes excessive autophagy, and blocks the flow of autophagy to induce autosis after IR. Conversely, knockdown of CDR1AS reversed the autophagy-related markers caused by IR, increasing cardiomyocyte activity, improving cardiac dysfunction and infarct area, and restoring the flow of autophagy. Further analysis of RNA sequencing and validation experiments revealed that CDR1AS aggravated autophagic damage, increased autophagosome accumulation, and promoted autosis by inhibiting the levels of LAMP2 and mTORC1 proteins. Additionally, RIP and pull-down assays showed that CDR1AS interacts with LAMP2 or mTORC1. First-time evidence reveals that circRNA CDR1AS regulates lysosomal membrane proteins by regulating the mTORC1/ULK1 pathway during myocardial IR-induced autosis. This suggests that maintaining moderate autophagy is a crucial part of the fight against myocardial IR damage.

Cardiac fibrosis is characterized by an elevated amount of extracellular matrix (ECM) within the heart. However, the persistence of cardiac fibrosis ultimately diminishes contractility and precipitates cardiac dysfunction. Circular RNAs (circRNAs) are emerging as important regulators of cardiac fibrosis. Here, we elucidate the functional role of a specific circular RNA CELF1 in cardiac fibrosis and delineate a novel feedback loop mechanism. Functionally, circ-CELF1 was involved in enhancing fibrosis-related markers' expression and promoting the proliferation of cardiac fibroblasts (CFs), thereby exacerbating cardiac fibrosis. Mechanistically, circ-CELF1 reduced the ubiquitination-degradation rate of BRPF3, leading to an elevation of BRPF3 protein levels. Additionally, BRPF3 acted as a modular scaffold for the recruitment of histone acetyltransferase KAT7 to facilitate the induction of H3K14 acetylation within the promoters of the Celf1 gene. Thus, the transcription of Celf1 was dramatically activated, thereby inhibiting the subsequent response of their downstream target gene Smad7 expression to promote cardiac fibrosis. Moreover, Celf1 further promoted Celf1 pre-mRNA transcription and back-splicing, thereby establishing a feedback loop for circ-CELF1 production. Consequently, a novel feedback loop involving CELF1/circ-CELF1/BRPF3/KAT7 was established, suggesting that circ-CELF1 may serve as a potential novel therapeutic target for cardiac fibrosis.

Activation of the intrinsic regenerative potential of adult mammalian hearts by promoting cardiomyocyte proliferation holds great potential in heart repair. CAND1 (Cullin-associated and neddylation-dissociated protein 1) functions as a critical regulator of cellular protein homeostasis by fine-tuning the ubiquitinated degradation of specific abnormally expressed protein substrates. Here, we identified that cardiac-specific transgenic overexpression of CAND1 reduced the infarct size, restored cardiac function, and promoted cardiomyocyte proliferation after myocardial infarction in juvenile (7-day-old) and adult (8-week-old) mice. Conversely, CAND1 deficiency blunted the regenerative capacity of neonatal hearts after apex resection. MS and functional verification demonstrated that CAND1 enhanced the assembly of Cullin1, FBXW11(F-box/WD repeat-containing protein 11), and Mob1b (Mps one binder kinase activator 1b) complexes, and thus promotes the degradation of Mob1b. The ubiquitination of Mob1b occurred at K108 and was linked by K48 of ubiquitin. Mob1b deletion partially rescued the loss of regenerative capacity in neonatal hearts induced by CAND1 deficiency and improved cardiac function in adult mice post-MI. Moreover, CAND1 promoted the proliferation of human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs). Our data demonstrate that CAND1 promotes cardiomyocyte proliferation via FBXW11-mediated K48-linked ubiquitination degradation of Mob1b, and improves heart regeneration after cardiac injury. The findings provide a novel strategy to promote cardiac regeneration and repair.

Cardiac conduction regulatory RNA (CCRR) has been documented as an antiarrhythmic lncRNA in our earlier investigation. This study aimed to evaluate the effects of CCRR on SERCA2a and the associated Ca2+ homeostasis in myocardial infarction (MI). Overexpression of CCRR via AAV9-mediated delivery not only partially reversed ischemia-induced contractile dysfunction but also alleviated abnormal Ca2+ homeostasis and reduced the heightened methylation level of SERCA2a following MI. These effects were also observed in CCRR over-expressing transgenic mice. A conserved sequence domain of CCRR mimicked the protective function observed with the full length. Furthermore, silencing CCRR in healthy mice led to intracellular Ca2+ overloading of cardiomyocytes. CCRR increased SERCA2a protein stability by upregulating FTO expression. The direct interaction between CCRR and FTO protein was characterized by RNA-binding protein immunoprecipitation (RIP) analysis and RNA pulldown experiments. Activation of NFATc3 was identified as an upstream mechanism responsible for CCRR downregulation in MI. This study demonstrates that CCRR is a protective lncRNA that acts by maintaining the function of FTO, thereby reducing the m6A RNA methylation level of SERCA2a, ultimately preserving calcium homeostasis for myocardial contractile function in MI. Therefore, CCRR may be considered a promising therapeutic strategy with a beneficial role in cardiac pathology.

Atrial fibrillation (AF) is the most common arrhythmia in the world. Human genetics can provide strong AF therapeutic candidates, but the identification of the causal genes and their functions remains challenging. Here, we applied an AF fine-mapping strategy that leverages results from a previously published cross- ancestry genome-wide association study (GWAS), expression quantitative trait loci (eQTLs) from left atrial appendages (LAAs) obtained from two cohorts with distinct ancestry, and a paired RNA sequencing (RNAseq) and ATAC sequencing (ATAC-seq) LAA single-nucleus assay (sn-multiome). At nine AF loci, our co- localization and fine-mapping analyses implicated 14 genes. Data integration identified several candidate causal AF variants, including rs7612445 at GNB4 and rs242557 at MAPT. . Finally, we showed that the repression of the strongest AF-associated eQTL gene, LINC01629, , in human embryonic stem cell-derived cardiomyocytes using CRISPR inhibition results in the dysregulation of pathways linked to genes involved in the development of atrial tissue and the cardiac conduction system.

BACKGROUND:G protein-coupled receptors play a critical role in atrial fibrillation (AF). Spexin is a novel ligand of galanin receptors (GALRs). In this study, we investigated the regulation of spexin and GALRs on AF and the underlying mechanisms. METHODS: Global spexin knockout (SPX-KO) and cardiomyocyte-specific GALRs knockout (GALR-cKO) mice underwent burst pacing electrical stimulation. Optical mapping was used to determine atrial conduction velocity and action potential duration. Atrial myocyte action potential duration and inward rectifying K+ current (I-K1) were recorded using whole-cell patch clamps. Isolated cardiomyocytes were stained with Fluo-3/AM dye, and intracellular Ca2+ handling was examined by CCD camera. A mouse model of AF was established by Ang-II (angiotensin II) infusion. RESULTS: Spexin plasma levels in patients with AF were lower than those in subjects without AF, and knockout of spexin increased AF susceptibility in mice. In the atrium of SPX-KO mice, potassium inwardly rectifying channel subfamily J member 2 (KCNJ2) and sarcolipin (SLN) were upregulated; meanwhile, I-K1 current was increased and Ca2+ handling was impaired in isolated atrial myocytes of SPX-KO mice. GALR2-cKO mice, but not GALR1-cKO and GALR3-cKO mice, had a higher incidence of AF, which was associated with higher I-K1 current and intracellular Ca2+ overload. The phosphorylation level of CREB (cyclic AMP responsive element binding protein 1) was upregulated in atrial tissues of SPX-KO and GALR2-cKO mice. Chromatin immunoprecipitation confirmed the recruitment of p-CREB to the proximal promoter regions of KCNJ2 and SLN. Finally, spexin treatment suppressed CREB signaling, decreased I-K1 current and intracellular Ca2+ overload, which thus reduced the inducibility of AF in Ang-II-infused mice. CONCLUSIONS: Spexin reduces atrial fibrillation susceptibility by inhibiting CREB phosphorylation and thus downregulating KCNJ2 and SLN transcription by GALR2 receptor. The spexin/GALR2/CREB signaling pathway represents a novel therapeutic avenue in the development of agents against atrial fibrillation.

Atrial fibrillation (AF) is the most common sustained arrhythmia which brings a heavy burden to the lives and health of patients worldwide. Our earlier research documented cardiac conduction regulatory RNA (CCRR) as an antiarrhythmic lncRNA in heart failure. Here, we report that CCRR was decreased in atrial tissue after MI, MYZAP, and Nav1.5 were increased in the atrium in cardiac-specific transgenic CCRR overexpression mice. Overexpression of CCRR carried by AAV-9 reversed the incidence and duration of AF and atrial conduction velocity in MI mice. MYZAP overexpression reversed the decreasing levels of PKP2, Nav1.5, and AF incidence after MI in addition to downregulating the expression levels of TLR2, TLR4, and inflammation-related factors following MI. Our work revealed that CCRR can improve the occurrence and development of AF after MI through the MYZAP-PKP2 pathway and inhibit Nav1.5 and TLR signaling pathways associated with inflammation, thus serving as a therapeutic target for AF.

Objective:Cold regions exhibit a high prevalence of cardiovascular disease,particularly acute myocardial infarction(AMI),which is one of the leading causes of death associated with cardiovascular conditions.Cardiovascular disease is closely linked to the abnormal expression of long non-coding RNA(lncRNA).This study investigates whether circulating levels of lncRNA cardiac conduction regulatory RNA(CCRR)could serve as a biomarker for AMI.Materials and methods:We measured circulating CCRR from whole blood samples collected from 68 AMI patients and 69 non-AMI subjects.An AMI model was established using C57BL/6 mice.Quantitative reverse transcription PCR(qRT-PCR)was used to assess CCRR expression.Exosomes were isolated from cardiomyocytes,and their characteristics were evaluated using electron microscope and nanoparticle tracking analysis.The exosome inhibitor GW4869 was employed to examine the effect of exosomal CCRR on cardiac function using echocardiography.Protein expression was detected using Western blot and immunofluorescence staining.Results:The circulating level of CCRR was significantly higher in AMI patients(1.93±0.13)than in non-AMI subjects(1.00±0.05,P<0.001).The area under the ROC curve(AUC)of circulating CCRR was 0.821.Similar changes in circulating CCRR levels were consistently observed in an AMI mouse model.Exosomal CCRR derived from hypoxia-induced cardiomyocytes and cardiac tissue after AMI were increased,a change that was reversed by GW4869.Additionally,CCRR-overexpressing exosomes improved cardiac function in AMI.Conclusion:Circulating lncRNA CCRR is a potential predictor of AMI.Exosomal CCRR plays a role in the communication between the heart and other organs through circulation.

Background: Timely and proper suppression of in fl ammation can effectively reduce myocardial injury and promote the postmyocardial infarction (post -MI) wound -healing process. We have previously found that cardiac conduction regulatory RNA (CCRR), a long noncoding RNA (lncRNA) transcribed by the gene located on chromosome 9, with abundant expression in the heart, elicits antiarrhythmic effects in heart failure, and this is a continuing study on the role of CCRR in MI. Methods: CCRR was overexpressed in CCRR transgenic mice or after injection of adeno-associated virus -9 (AAV-9). MI surgery was performed, and cardiac function was assessed in vivo by echocardiography, followed by histologic analyses. Western blot analysis and qRTPCR were performed to investigate the effects of CCRR on macrophages, cardiomyocytes, and cardiomyocytes cocultured with macrophages. Through microarray analysis and RNA -binding protein immunoprecipitation (RIP) and other related techniques were also employed to study the effects of CCRR on Toll -like receptor (TLR)2 and TLR4. Results: We found that CCRR level was signi fi cantly decreased with increases in proin fl ammatory cytokines and activation of the TLR signalling pathway in the heart of the 3 -day MI mice. CCRR overexpression downregulated TLR2 and TLR4 in MI and effectively inhibited the in fl ammatory responses in primary cardiomyocytes and macrophages cultured under hypoxic conditions. Downregulation of CCRR induced excessive in fl ammatory responses by activating the TLR signalling pathway. CCRR acted by suppressing TLR2 and TLR4 to inhibit the secretion of proin fl ammatory factors to reduce infarct size, thereby improving cardiac function. Conclusions: CCRR protected cardiomyocytes against MI injury by suppressing in fl ammatory response through targeting the TLR signalling pathway.

In the healing process of myocardial infarction, cardiac fibroblasts are activated to produce collagen, leading to adverse remodeling and heart failure. Our previous study showed that ASPP1 promotes cardiomyocyte apoptosis by enhancing the nuclear trafficking of p53. We thus explored the influence of ASPP1 on myocardial fibrosis and the underlying mechanisms. Here, we observed that ASPP1 was increased after 4 weeks of MI. Both global and myofibroblast knockout of ASPP1 in mice mitigated cardiac dysfunction and fibrosis after MI. Strikingly, ASPP1 produced the opposite influence on p53 level and cell fate in cardiac fibroblasts and cardiomyocytes. Knockdown of ASPP1 increased p53 levels and inhibited the activity of cardiac fibroblasts. ASPP1 accumulated in the cytoplasm of fibroblasts while the level of p53 was reduced following TGF-beta 1 stimulation; however, inhibition of ASPP1 increased the p53 level and promoted p53 nuclear translocation. Mechanistically, ASPP1 is directly bound to deubiquitinase OTUB1, thereby promoting the ubiquitination and degradation of p53, attenuating myofibroblast activity and cardiac fibrosis, and improving heart function after MI. ASPP1 promotes apoptosis of cardiomyocytes by increasing the trafficking of p53 to the nucleus. Here the authors show that, in fibroblasts, ASPP1 promotes the ubiquitination and degradation of p53, decreasing myofibroblast activity and improving cardiac fibrosis and function after myocardial infarction.

The interaction between macrophages and cardiomyocytes plays an important role not only in maintaining cardiac homeostasis, but also in the development of many cardiovascular diseases (CVDs), such as myocardial infarction (MI) and heart failure (HF). In addition to supporting cardiomyocytes, macrophages and cardiomyocytes have a close and complex relationship. By studying their cross-talk, we can better understand novel mechanisms and target pathogenic mechanisms, and improve the treatment of CVDs. We review macrophage-cardiomyocyte communication through connexin 43 (Cx43)-containing gap junctions (GJs) directly, secreted protein factors indirectly, and discuss the implications of these interactions in cardiac homeostasis and the development of various CVDs, including MI, HF, arrhythmia, cardiac fibrosis and myocarditis. In this section, we review various drugs that work by modulating cytokines or other proteins to reduce inflammation in CVDs. The clinical findings from targeting inflammation in CVDs are also discussed. Additionally, we examine the challenges and opportunities for improving our understanding of macrophage-cardiomyocyte coupling as it relates to pathophysiological disease processes, extending our research scope, and helping identify new molecular targets and improve the effectiveness of existing therapies.