This study aimed to investigate the underlying mechanism of Zhenwu Decoction in the treatment of heart failure by regulating electrical remodeling through the transient outward potassium current(I_(to))/voltage-gated potassium(Kv) channels. Five normal SD rats were intragastrically administered with Zhenwu Decoction granules to prepare drug-containing serum, and another seven normal SD rats received an equal amount of distilled water to prepare blank serum. H9c2 cardiomyocytes underwent conventional passage and were treated with angiotensin Ⅱ(AngⅡ) for 24 h. Subsequently, 2%, 4%, and 8% drug-containing serum, simvastatin(SIM), and BaCl_2 were used to interfere in H9c2 cardiomyocytes for 24 h. The cells were divided into a control group [N, 10% blank serum + 90% high-glucose DMEM(DMEM-H)], a model group(M, AngⅡ + 10% blank serum + 90% DMEM-H), a low-dose Zhenwu Decoction-containing serum group(Z1, AngⅡ + 2% drug-containing serum of Zhenwu Decoction + 8% blank serum + 90% DMEM-H), a medium-dose Zhenwu Decoction-containing serum group(Z2, AngⅡ + 4% drug-containing serum of Zhenwu Decoc-tion + 6% blank serum + 90% DMEM-H), a high-dose Zhenwu Decoction-containing serum group(Z3, AngⅡ + 8% drug-containing serum of Zhenwu Decoction + 2% blank serum + 90% DMEM-H), an inducer group(YD, AngⅡ + SIM + 10% blank serum + 90% DMEM-H), and an inhibitor group(YZ, AngⅡ + BaCl_2 + 10% blank serum + 90% DMEM-H). The content of ANP in cell extracts of each group was detected by ELISA. The relative mRNA expression levels of ANP, Kv1.4, Kv4.2, Kv4.3, DPP6, and KChIP2 were detected by real-time quantitative PCR. The protein expression of Kv1.4, Kv4.2, Kv4.3, DPP6, and KChIP2 was detected by Western blot. I_(to) was detected by the whole cell patch-clamp technique. The results showed that Zhenwu Decoction at low, medium, and high doses could effectively reduce the surface area of cardiomyocytes. Compared with the M group, the Z1, Z2, Z3, and YD groups showed decreased ANP content and mRNA level, increased protein and mRNA expression of Kv4.2, Kv4.3, DPP6, and KChIP2, and decreased protein and mRNA expression of Kv1.4, and the aforementioned changes were the most notable in the Z3 group. Compared with the N group, the Z1, Z2, and Z3 groups showed significantly increased peak current and current density of I_(to). The results indicate that Zhenwu Decoction can regulate myocardial remodeling and electrical remodeling by improving the expression trend of Kv1.4, Kv4.2, Kv4.3, KChIP2, and DPP6 proteins and inducing I_(to) to regulate Kv channels, which may be one of the mechanisms of Zhenwu Decoction in treating heart failure and related arrhythmias.
Rats ; Animals ; Myocytes, Cardiac ; Atrial Remodeling ; Rats, Sprague-Dawley ; Heart Failure/metabolism* ; RNA, Messenger/metabolism* ; Potassium

Tetramethylpyrazine is the main component of Ligusticum chuanxiong. Studies have found that tetramethylpyrazine has a good protective effect against cardiovascular diseases. In the heart, tetramethylpyrazine can reduce myocardial ischemia/reperfusion injury by inhibiting oxidative stress, regulating autophagy, and inhibiting cardiomyocyte apoptosis. Tetramethylpyrazine can also reduce the damage of cardiomyocytes caused by inflammation, relieve the fibrosis and hypertrophy of cardiomyocytes in infarcted myocardium, and inhibit the expansion of the cardiac cavity after myocardial infarction. In addition, tetramethylpyrazine also has a protective effect on the improvement of familial dilated cardiomyopathy. Besides, the mechanisms of tetramethylpyrazine on blood vessels are more abundant. It can inhibit endothelial cell apoptosis by reducing oxidative stress, maintain vascular endothelial function and homeostasis by inhibiting inflammation and glycocalyx degradation, and protect vascular endothelial cells by reducing iron overload. Tetramethylpyrazine also has a certain inhibitory effect on thrombosis. It can play an anti-thrombotic effect by reducing inflammatory factors and adhesion molecules, inhibiting platelet aggregation, and suppressing the expression of fibrinogen and von Willebrand factor. In addition, tetramethylpyrazine can also reduce the level of blood lipid in apolipoprotein E-deficient mice, inhibit the subcutaneous deposition of lipids, inhibit the transformation of macrophages into foam cells, and inhibit the proliferation and migration of vascular smooth muscle cells, thereby reducing the formation of atherosclerotic plaque. In combination with network pharmacology, the protective mechanism of tetramethylpyrazine on the cardiovascular system may be mainly achieved through the regulation of phosphatidylinositol 3 kinase/protein kinase B(PI3K/Akt), hypoxia-inducible factor 1(HIF-1), and mitogen-activated protein kinase(MAPK) pathways. Tetramethylpyrazine hydrochloride and sodium chloride injection has been approved for clinical application, but some adverse reactions have been found in clinical application, which need to be paid attention to.
Mice ; Animals ; Endothelial Cells/metabolism* ; Phosphatidylinositol 3-Kinases/metabolism* ; Myocardial Infarction ; Myocardium/metabolism* ; Myocytes, Cardiac ; Thrombosis ; Inflammation ; Apoptosis

OBJECTIVES: Hyperhomocysteinaemia (Hcy) is an independent risk factor for cardiovascular and cerebrovascular diseases. MicroRNA (miR)-18a-5p is closely related to cardiovascular diseases. This study aims to investigate the effects of miR-18a-5p on homocysteine (Hcy)-induced myocardial cells injury. METHODS: H9c2 cells were transfected with miR-18a-5p mimic/miR-18a-5p mimic negative control (NC) or combined with Hcy for intervention, and untreated cells were set as a control group. The transfection efficiency was verified by real-time RT-PCR, and cell counting kit-8 (CCK-8) assay was used to determine cell viability. Flow cytometry was used to detect apoptosis and reactive oxygen species (ROS) levels. Western blotting was performed to measure the protein levels of microtubule-associated protein 1 light chain 3 (LC3)-I, LC3-II, Beclin1, p62, Bax, Bcl-2, and Notch2. Dual luciferase reporter assay was used to detect the interaction of miR-18a-5p with Notch2. RESULTS: Compared with the control, treatment with Hcy or transfection with miR-18a-5p mimic alone, or combined treatment with Hcy and miR-18a-5p mimic/miR-18a-5p mimic NC significantly reduced the H9c2 cell viability, promoted apoptosis and ROS production, up-regulated the expressions of Bax and Beclin, down-regulated the expressions of Bcl-2, p62, and Notch2, and increased the ratio of LC3-II/LC3-I (all P<0.05). Compared with the combined intervention of miR-18a-5p mimic NC and Hcy group, the above indexes were more significantly changed in the combined intervention of miR-18a-5p mimic and Hcy group, and the difference between the 2 groups was statistically significant (all P<0.05). There is a targeted binding between Notch2 and miR-18a-5p. CONCLUSIONS MiR-18a-5p could induce autophagy and apoptosis via increasing ROS production in cardiomyocytes, and aggravate Hcy-induced myocardial injury. Notch2 is a target of miR-18a-5p.
Apoptosis/genetics* ; Autophagy/genetics* ; bcl-2-Associated X Protein ; MicroRNAs/metabolism* ; Proto-Oncogene Proteins c-bcl-2/genetics* ; Reactive Oxygen Species ; Rats ; Animals ; Myocytes, Cardiac/drug effects* ; Homocysteine/adverse effects* ; Hyperhomocysteinemia

A small proportion of mononuclear diploid cardiomyocytes (MNDCMs), with regeneration potential, could persist in adult mammalian heart. However, the heterogeneity of MNDCMs and changes during development remains to be illuminated. To this end, 12 645 cardiac cells were generated from embryonic day 17.5 and postnatal days 2 and 8 mice by single-cell RNA sequencing. Three cardiac developmental paths were identified: two switching to cardiomyocytes (CM) maturation with close CM-fibroblast (FB) communications and one maintaining MNDCM status with least CM-FB communications. Proliferative MNDCMs having interactions with macrophages and non-proliferative MNDCMs (non-pMNDCMs) with minimal cell-cell communications were identified in the third path. The non-pMNDCMs possessed distinct properties: the lowest mitochondrial metabolisms, the highest glycolysis, and high expression of Myl4 and Tnni1. Single-nucleus RNA sequencing and immunohistochemical staining further proved that the Myl4⁺Tnni1⁺ MNDCMs persisted in embryonic and adult hearts. These MNDCMs were mapped to the heart by integrating the spatial and single-cell transcriptomic data. In conclusion, a novel non-pMNDCM subpopulation with minimal cell-cell communications was unveiled, highlighting the importance of microenvironment contribution to CM fate during maturation. These findings could improve the understanding of MNDCM heterogeneity and cardiac development, thus providing new clues for approaches to effective cardiac regeneration.
Animals ; Mice ; Diploidy ; Heart ; Myocytes, Cardiac/metabolism* ; Cell Communication ; Gene Expression Profiling ; Mitochondria ; Regeneration ; Mammals/genetics*

BACKGROUND: Sarcoplasmic reticulum calcium ATPase 2a (SERCA2a) is a key protein that maintains myocardial Ca 2+ homeostasis. The present study aimed to investigate the mechanism underlying the SERCA2a-SUMOylation (small ubiquitin-like modifier) process after ischemia/reperfusion injury (I/RI) in vitro and in vivo . METHODS: Calcium transient and systolic/diastolic function of cardiomyocytes isolated from Serca2a knockout (KO) and wild-type mice with I/RI were compared. SUMO-relevant protein expression and localization were detected by quantitative real-time PCR (RT-qPCR), Western blotting, and immunofluorescence in vitro and in vivo . Serca2a-SUMOylation, infarct size, and cardiac function of Senp1 or Senp2 overexpressed/suppressed adenovirus infected cardiomyocytes, were detected by immunoprecipitation, triphenyltetrazolium chloride (TTC)-Evans blue staining, and echocardiography respectively. RESULTS: The results showed that the changes of Fura-2 fluorescence intensity and contraction amplitude of cardiomyocytes decreased in the I/RI groups and were further reduced in the Serca2a KO + I/RI groups. Senp1 and Senp2 messenger ribose nucleic acid (mRNA) and protein expression levels in vivo and in cardiomyocytes were highest at 6 h and declined at 12 h after I/RI. However, the highest levels in HL-1 cells were recorded at 12 h. Senp2 expression increased in the cytoplasm, unlike that of Senp1. Inhibition of Senp2 protein reversed the I/RI-induced Serca2a-SUMOylation decline, reduced the infarction area, and improved cardiac function, while inhibition of Senp1 protein could not restore the above indicators. CONCLUSION I/RI activated Senp1 and Senp2 protein expression, which promoted Serca2a-deSUMOylation, while inhibition of Senp2 expression reversed Serca2a-SUMOylation and improved cardiac function.
Animals ; Mice ; Calcium/metabolism* ; Cysteine Endopeptidases/metabolism* ; Myocardial Reperfusion Injury/metabolism* ; Myocardium/metabolism* ; Myocytes, Cardiac/metabolism* ; Proteins/metabolism* ; Sarcoplasmic Reticulum Calcium-Transporting ATPases/genetics*

Objective To investigate the effect of viral myocarditis serum exosomal miR-320 on apoptosis of cardiomyocytes and its mechanism. Methods The model of viral myocarditis mice was established by intraperitoneal injection of Coxsackie virus B3. Serum exosomes were extracted by serum exosome extraction kit and co-cultured with cardiomyocytes. The uptake of exosomes by cardiomyocytes was detected by laser confocal microscopy. Cardiomyocytes were transfected with miR-320 inhibitor or mimic, and the expression level of miR-320 was detected by real-time quantitative PCR. Flow cytometry was used to detect cardiomyocyte apoptosis rate, and the expression levels of B cell lymphoma 2 (Bcl2) and Bcl2-related X protein (BAX) were tested by Western blot analysis. The prediction of miR-320 target genes and GO and KEGG enrichment analysis were tested by online database. The relationship between miR-320 and its target gene phosphoinositide-3-kinase regulatory subunit 1(Pik3r1) was examined by luciferase reporter gene. The effect of miR-320 on AKT/mTOR pathway protein was detected by Western blot analysis. Results Viral myocarditis serum exosomes promoted cardiomyocyte apoptosis, and increased the level of BAX while the level of Bcl2 was decreased. miR-320 was significantly up-regulated in myocardial tissue of viral myocarditis mice, and both pri-miR-320 and mature of miR-320 were up-regulated greatly in cardiomyocytes. The level of miR-320 in cardiomyocytes treated with viral myocarditis serum exosomes was significantly up-regulated, while transfection of miR-320 inhibitor counteracted miR-320 overexpression and reduced apoptosis rate caused by exosomes. Pik3r1 is the target gene of miR-320, and its overexpression reversed cardiomyocyte apoptosis induced by miR-320 up-regulation. The overexpression of miR-320 inhibited AKT/mTOR pathway activation. Conclusion Viral myocarditis serum exosome-derived miR-320 promotes apoptosis of mouse cardiomyocytes by inhibiting AKT/mTOR pathway by targeting Pik3r1.
Mice ; Animals ; Myocytes, Cardiac ; Phosphatidylinositol 3-Kinase/metabolism* ; Proto-Oncogene Proteins c-akt/metabolism* ; Myocarditis/pathology* ; Exosomes/metabolism* ; bcl-2-Associated X Protein/metabolism* ; MicroRNAs/metabolism* ; TOR Serine-Threonine Kinases/metabolism* ; Apoptosis/genetics*

Aging poses a major risk factor for cardiovascular diseases, the leading cause of death in the aged population. However, the cell type-specific changes underlying cardiac aging are far from being clear. Here, we performed single-nucleus RNA-sequencing analysis of left ventricles from young and aged cynomolgus monkeys to define cell composition changes and transcriptomic alterations across different cell types associated with age. We found that aged cardiomyocytes underwent a dramatic loss in cell numbers and profound fluctuations in transcriptional profiles. Via transcription regulatory network analysis, we identified FOXP1, a core transcription factor in organ development, as a key downregulated factor in aged cardiomyocytes, concomitant with the dysregulation of FOXP1 target genes associated with heart function and cardiac diseases. Consistently, the deficiency of FOXP1 led to hypertrophic and senescent phenotypes in human embryonic stem cell-derived cardiomyocytes. Altogether, our findings depict the cellular and molecular landscape of ventricular aging at the single-cell resolution, and identify drivers for primate cardiac aging and potential targets for intervention against cardiac aging and associated diseases.
Aged ; Animals ; Humans ; Aging/genetics* ; Forkhead Transcription Factors/metabolism* ; Myocytes, Cardiac/metabolism* ; Primates/metabolism* ; Repressor Proteins/metabolism* ; Transcriptome ; Macaca fascicularis/metabolism*

Mammals exhibit limited heart regeneration ability, which can lead to heart failure after myocardial infarction. In contrast, zebrafish exhibit remarkable cardiac regeneration capacity. Several cell types and signaling pathways have been reported to participate in this process. However, a comprehensive analysis of how different cells and signals interact and coordinate to regulate cardiac regeneration is unavailable. We collected major cardiac cell types from zebrafish and performed high-precision single-cell transcriptome analyses during both development and post-injury regeneration. We revealed the cellular heterogeneity as well as the molecular progress of cardiomyocytes during these processes, and identified a subtype of atrial cardiomyocyte exhibiting a stem-like state which may transdifferentiate into ventricular cardiomyocytes during regeneration. Furthermore, we identified a regeneration-induced cell (RIC) population in the epicardium-derived cells (EPDC), and demonstrated Angiopoietin 4 (Angpt4) as a specific regulator of heart regeneration. angpt4 expression is specifically and transiently activated in RIC, which initiates a signaling cascade from EPDC to endocardium through the Tie2-MAPK pathway, and further induces activation of cathepsin K in cardiomyocytes through RA signaling. Loss of angpt4 leads to defects in scar tissue resolution and cardiomyocyte proliferation, while overexpression of angpt4 accelerates regeneration. Furthermore, we found that ANGPT4 could enhance proliferation of neonatal rat cardiomyocytes, and promote cardiac repair in mice after myocardial infarction, indicating that the function of Angpt4 is conserved in mammals. Our study provides a mechanistic understanding of heart regeneration at single-cell precision, identifies Angpt4 as a key regulator of cardiomyocyte proliferation and regeneration, and offers a novel therapeutic target for improved recovery after human heart injuries.
Humans ; Mice ; Rats ; Cell Proliferation ; Heart/physiology* ; Mammals ; Myocardial Infarction/metabolism* ; Myocytes, Cardiac/metabolism* ; Pericardium/metabolism* ; Single-Cell Analysis ; Zebrafish/metabolism*

OBJECTIVE: To investigate the effects of tanshinone IIA on apoptosis and autophagy induced by hypoxia/reoxygenation in H9C2 cardiomyocytes and its mechanism. METHODS: H9C2 cardiomyocytes in logarithmic growth phase were divided into control group, hypoxia/reoxygenation model group and tanshinone IIA low-dose, medium-dose and high-dose groups (50, 100, 200 mg/L tanshinone IIA were treated after hypoxia/reoxygenation respectively). The dose with good therapeutic effect was selected for follow-up study. The cells were divided into control group, hypoxia/reoxygenation model group, tanshinone IIA+pcDNA3.1-NC group and tanshinone IIA+pcDNA3.1-ABCE1 group. The cells were transfected with the overexpressed plasmids pcDNA3.1-ABCE1 and pcDNA3.1-NC and then treated accordingly. Cell counting kit-8 (CCK-8) was used to detect H9C2 cell activity in each group. The apoptosis rate of cardiomyocytes was detected by flow cytometry. The ATP-binding cassette transporter E1 (ABCE1), apoptosis-related proteins Bcl-2 and Bax, caspase-3, autophagy-related proteins Beclin-1, microtubule-associated protein 1 light chain 3 (LC3II/I) and p62 mRNA expression level of H9C2 cells in each group were detected by real-time fluorescence quantitative reverse transcription-polymerase chain reaction (RT-qPCR). The protein expression levels of the above indexes in H9C2 cells were detected by Western blotting. RESULTS: (1) Cell activity and ABCE1 expression: tanshinone IIA inhibited the activity of H9C2 cells induced by hypoxia/reoxygenation, and the effect was significant at medium-dose [(0.95±0.05)% vs. (0.37±0.10)%, P < 0.01], mRNA and protein expression of ABCE1 were significantly reduced [ABCE1 mRNA (2^-ΔΔCt): 2.02±0.13 vs. 3.74±0.17, ABCE1 protein (ABCE1/GAPDH): 0.46±0.04 vs. 0.68±0.07, both P < 0.05]. (2) Expression of apoptosis-related proteins: medium-dose of tanshinone IIA inhibited the apoptosis of H9C2 cells induced by hypoxia/reoxygenation [apoptosis rate: (28.26±2.52)% vs. (45.27±3.07)%, P < 0.05]. Compared with the hypoxia/reoxygenation model group, medium-dose of tanshinone IIA significantly down-regulated the protein expression of Bax and caspase-3 in H9C2 cells induced by hypoxia/reoxygenation, and significantly up-regulated the protein expression of Bcl-2 [Bax (Bax/GAPDH): 0.28±0.03 vs. 0.47±0.03, caspase-3 (caspase-3/GAPDH): 0.31±0.02 vs. 0.44±0.03, Bcl-2 (Bcl-2/GAPDH): 0.53±0.02 vs. 0.37±0.05, all P < 0.05]. (3) Expression of autophagy-related proteins: compared with the control group, the positive rate of LC3 in the hypoxia/reoxygenation model group was significantly increased, while the positive rate of LC3 in the medium-dose of tanshinone IIA group was significantly decreased [(20.67±3.09)% vs. (42.67±3.86)%, P < 0.01]. Compared with hypoxia/reoxygenation model group, medium-dose of tanshinone IIA significantly down-regulated Beclin-1, LC3II/I and p62 protein expressions [Beclin-1 (Beclin-1/GAPDH): 0.27±0.05 vs. 0.47±0.03, LC3II/I ratio: 0.24±0.05 vs. 0.47±0.04, p62 (p62/GAPDH): 0.21±0.03 vs. 0.48±0.02, all P < 0.05]. (4) Expression of apoptosis and autophagy related proteins after transfection with overexpressed ABCE1 plasmid: compared with tanshinone IIA+pcDNA3.1-NC group, the protein expression levels of Bax, caspase-3, Beclin-1, LC3II/I and p62 in tanshinone IIA+pcDNA3.1-ABCE1 group were significantly up-regulated, while the protein expression level of Bcl-2 was significantly down-regulated. CONCLUSIONS 100 mg/L tanshinone IIA could inhibit autophagy and apoptosis of cardiomyocytes by regulating the expression level of ABCE1. So, it protects H9C2 cardiomyocytes injury induced by hypoxia/reoxygenation.
Humans ; Apoptosis ; ATP-Binding Cassette Transporters/metabolism* ; Autophagy ; bcl-2-Associated X Protein/metabolism* ; Beclin-1/metabolism* ; Caspase 3/metabolism* ; Follow-Up Studies ; Myocytes, Cardiac ; Proto-Oncogene Proteins c-bcl-2/metabolism* ; RNA, Messenger/metabolism* ; Cell Hypoxia

Oxidative stress plays a crucial role in cadmium (Cd)-induced myocardial injury. Mitsugumin 53 (MG53) and its mediated reperfusion injury salvage kinase (RISK) pathway have been demonstrated to be closely related to myocardial oxidative damage. Potentilla anserina L. polysaccharide (PAP) is a polysaccharide with antioxidant capacity, which exerts protective effect on Cd-induced damage. However, it remains unknown whether PAP can prevent and treat Cd-induced cardiomyocyte damages. The present study was desgined to explore the effect of PAP on Cd-induced damage in H9c2 cells based on MG53 and the mediated RISK pathway. For in vitro evaluation, cell viability and apoptosis rate were analyzed by CCK-8 assay and flow cytometry, respectively. Furthermore, oxidative stress was assessed by 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA) staining and using superoxide dismutase (SOD), catalase (CAT), and glutathione/oxidized glutathione (GSH/GSSG) kits. The mitochondrial function was measured by JC-10 staining and ATP detection assay. Western blot was performed to detect the expression of proteins related to MG53, the RISK pathway, and apoptosis. The results indicated that Cd increased the levels of reactive oxygen species (ROS) in H9c2 cells. Cd decreased the activities of SOD and CAT and the ratio of GSH/GSSG, resulting in decreases in cell viability and increases in apoptosis. Interestingly, PAP reversed Cd-induced oxidative stress and cell apoptosis. Meanwhile, Cd reduced the expression of MG53 in H9c2 cells and inhibited the RISK pathway, which was mediated by decreasing the ratio of p-Akt^Ser473/Akt, p-GSK3β^Ser9/GSK3β and p-ERK1/2/ERK1/2. In addition, Cd impaired mitochondrial function, which involved a reduction in ATP content and mitochondrial membrane potential (MMP), and an increase in the ratio of Bax/Bcl-2, cytoplasmic cytochrome c/mitochondrial cytochrome c, and Cleaved-Caspase 3/Pro-Caspase 3. Importantly, PAP alleviated Cd-induced MG53 reduction, activated the RISK pathway, and reduced mitochondrial damage. Interestingly, knockdown of MG53 or inhibition of the RISK pathway attenuated the protective effect of PAP in Cd-induced H9c2 cells. In sum, PAP reduces Cd-induced damage in H9c2 cells, which is mediated by increasing MG53 expression and activating the RISK pathway.
Cadmium/metabolism* ; Caspase 3/metabolism* ; Potentilla/metabolism* ; Glycogen Synthase Kinase 3 beta/pharmacology* ; Proto-Oncogene Proteins c-akt/metabolism* ; Cytochromes c/metabolism* ; Glutathione Disulfide/pharmacology* ; Oxidative Stress ; Myocytes, Cardiac ; Reactive Oxygen Species/metabolism* ; Reperfusion Injury/metabolism* ; Apoptosis ; Polysaccharides/pharmacology* ; Adenosine Triphosphate/metabolism*