Ischemic heart disease (IHD) remains a major global health concern, with ischemia-reperfusion injury exacerbating myocardial damage despite therapeutic interventions. In this study, we investigated the role of tropomyosin 3 (TPM3) in protecting cardiomyocytes against hypoxia-induced injury and oxidative stress. Using the AC16 and H9c2 cell lines, we established a chemical hypoxia model by treating cells with cobalt chloride (CoCl2) to simulate low-oxygen conditions. We found that CoCl2 treatment significantly upregulated the expression of hypoxia-inducible factor 1 alpha (HIF-1α) in cardiomyocytes, indicating the successful induction of hypoxia. Subsequent morphological and biochemical analyses revealed that hypoxia altered cardiomyocyte morphology disrupted the cytoskeleton, and caused cellular damage, accompanied by increased lactate dehydrogenase (LDH) release and malondialdehyde (MDA) levels, and decreased superoxide dismutase (SOD) activity, indicative of oxidative stress. Lentivirus-mediated TPM3 overexpression attenuated hypoxia-induced morphological changes, cellular damage, and oxidative stress imbalance, while TPM3 knockdown exacerbated these effects. Furthermore, treatment with the HDAC1 inhibitor MGCD0103 partially reversed the exacerbation of hypoxia-induced injury caused by TPM3 knockdown. Protein-protein interaction (PPI) network and functional enrichment analysis suggested that TPM3 may modulate cardiac muscle development, contraction, and adrenergic signaling pathways. In conclusion, our findings highlight the therapeutic potential of TPM3 modulation in mitigating hypoxia-associated cardiac injury, suggesting a promising avenue for the treatment of ischemic heart disease and other hypoxia-related cardiac pathologies.

In our previous study, a screening of a variety of lycotonine-type diterpenoid alkaloids were screened for cardiotonic activity revealed that lycoctonine had moderate cardiac effect. In this study, a series of structurally diverse of lycoctonine were synthesized by modifying on B-ring, D-ring, E-ring, F-ring, N-atom or salt formation on lycoctonine skeleton. We evaluated the cardiotonic activity of the derivatives by isolated frog heart, aiming to identify some compounds with significantly enhanced cardiac effects, among which compound 27 with a N-isobutyl group emerged as the most promising cardiotonic candidate. Furthermore, the cardiotonic mechanism of compound 27 was preliminarily investigated. The result suggested that the cardiotonic effect of compound 27 is related to calcium channels. Patch clamp technique confirmed that the compound 27 had inhibitory effects on CaV1.2 and CaV3.2, with inhibition rates of 78.52 % ± 2.26 % and 79.05 % ± 1.59 % at the concentration of 50 μM, respectively. Subsequently, the protective effect of 27 on H9c2 cells injury induced by cobalt chloride was tested. In addition, compound 27 can alleviate CoCl2-induced myocardial injury by alleviating calcium overload. These findings suggest that compound 27 was a new structural derived from lycoctonine, which may serve as a new lead compound for the treatment of heart failure.

BACKGROUND: Long-term exposure of humans to air pollution is associated with an increasing risk of cardiovascular diseases (CVDs). Astaxanthin (AST), a naturally occurring red carotenoid pigment, was proved to have multiple health benefits. However, whether or not AST also exerts a protective effect on fine particulate matter (PM2.5)-induced cardiomyocyte damage and its underlying mechanisms remain unclear.
METHODS: In vitro experiments, the H9C2 cells were subjected to pretreatment with varying concentrations of AST, and then cardiomyocyte injury model induced by PM2.5 was established. The cell viability and the ferroptosis-related proteins expression were measured in different groups. In vivo experiments, the rats were pretreated with different concentrations of AST for 21 days. Subsequently, a rat model of myocardial PM2.5 injury was established by intratracheal instillation every other day for 1 week. The effects of AST on myocardial tissue injury caused by PM2.5 indicating by histological, serum, and protein analyses were examined.
RESULTS: AST significantly ameliorated PM2.5-induced myocardial tissue injury, inflammatory cell infiltration, the release of inflammatory factors, and cardiomyocyte H9C2 cell damage. Mechanistically, AST pretreatment increased the expression of SLC7A11, GPX4 and down-regulated the expression of TfR1, FTL and FTH1 in vitro and in vivo.
CONCLUSIONS: Our study suggest that ferroptosis plays a significant role in the pathogenesis of cardiomyocyte injury induced by PM2.5. AST may serve as a potential therapeutic agent for mitigating cardiomyocyte injury caused by PM2.5 through the inhibition of ferroptosis.

This study aimed to observe the mechanism and effect of circ_0004771 on cardiomyocyte injury in acute myocardial infarction (AMI). The differences in circ_0004771 expression in the blood of AMI patients and healthy volunteers were observed by Real-Time Quantitative Reverse Transcription-Polymerase Chain Reaction. AMI cell models were constructed by hypoxia/reoxygenation (H/R)-induced injury in human cardiomyocytes (AC16 cells). The changes of circ_0004771 expression in AMI cells were observed. After transfection with the knockdown or overexpression of circ_0004771 vector in AMI cells, Cell Counting Kit-8 (CCK-8) assay and propidium iodide/FITC-Annexin V staining were performed to detect cell proliferation and apoptosis levels, extracellular lactate dehydrogenase (LDH) activity, malondialdehyde (MDA) concentration, and superoxide dismutase (SOD) activity. Expression levels of Mitogen-activated protein kinase (MAPK) signaling pathway-related proteins (p-MEK1/2, MEK1/2, p-ERK1/2, ERK1/2), and endoplasmic reticulum (ER) stress proteins (GRP78 and CHOP-1) were observed in each group of cells by western blot method. The expression level of circ_0004771 was significantly reduced in both clinical samples and cells of AMI. When circ_0004771 was knocked down in AMI cells, it resulted in a decrease in cell proliferation level and significant increase in apoptosis level. The inhibition of circ_0004771 expression caused leakage of LDH in AMI cells, accumulation of intracellular MDA, and inhibition of SOD activity. In addition, the knockdown of circ_0004771 significantly increased the levels of p-MEK1/2, p-ERK1/2, GRP78, and CHOP-1 in H/R-induced AC16 cells. However, the overexpression of circ_0004771 resulted in the opposite result as when circ_0004771 was knocked down. A low level of circ_0004771 in AMI activates the MAPK signaling pathway in cardiomyocytes as well as encourages intracellular oxidative stress and ER stress, thereby inhibiting cell proliferation and promoting apoptosis.

OBJECTIVE: Tanshinone IIA has a wide range of myocardial protective effects. AK003290 is a long noncoding RNA (lncRNA) that is highly expressed in myocardial tissue, and its expression is down-regulated when myocardial injury occurs. This study aims to explore the mechanism for tanshinone IIA in alleviating myocardial cell damage induced by oxygen glucose deprivation (OGD).
METHODS: OGD model was established in rat H9C2 cardiomyocytes. siRNA was transfected to reduce AK003290 expression. H9C2 cells were divided into 6 groups: A control group, a tanshinone IIA (TAN) group, an OGD group, a tanshinone IIA+OGD (TAN+OGD) group, a scrambled siRNA transfection+tanshinone IIA+OGD (scrambled siRNA+TAN+OGD) group, and a AK003290 siRNA transfection+tanshinone IIA+OGD (AK003290 siRNA+TAN+OGD) group. H9C2 cells in the TAN group were treated with 40 μmol/L tanshinone IIA for 12 h. The TAN+OGD group was treated with 40 μmol/L tanshinone IIA for 12 h, followed by OGD treatment for 12 h. The scrambled siRNA+TAN+OGD group and AK003290 siRNA+TAN+OGD group were transfected with the scrambled siRNA or AK003290 siRNA. Twenty-four hours later, the cells were treated with tanshinone IIA and OGD. Real-time RT-PCR was used to detect the expression of AK003290. Spectrophotometry was used to detect the content of lactate dehydrogenase (LDH) in cell culture medium to reflect LDH leakage rate, and enzyme-linked immunosorbent assay (ELISA) was used to detect the content of interleukin-1β (IL-1β) and interleukin-18 (IL-18). Western blotting was used to detect the protein expression of phospho-nuclear factor- κB (p-NF-κB).
RESULTS: Compared with the control group, the leakage rate of LDH, the content of IL-1β and IL-18 in culture medium, and the protein expression level of p-NF-κB were increased in the OGD group (P<0.01 or P<0.001). Compared with the OGD group, the leakage rate of LDH, the content of IL-1β and IL-18 in culture medium, and the protein expression level of p-NF-κB were decreased in the TAN+OGD group (P<0.05 or P<0.01). Compared with the control group, the AK003290 expression was increased in the TAN group (P<0.01) and it was decreased in the OGD group (P<0.05). Compared with the OGD group, the AK003290 expression was increased in the TAN+OGD group (P<0.05). Compared with the scrambled siRNA+TAN+OGD group, the leakage rate of LDH, the content of IL-1β and IL-18 in culture medium, and the protein expression level of p-NF-κB were increased in the AK003290 siRNA+TAN+OGD group (P<0.05 or P<0.01).
CONCLUSIONS: Tanshinone IIA inhibits NF-κB activity and attenuates OGD-induced inflammatory injury of cardiomyocytes through up-regulating AK003290.
目的: 丹参酮ⅡA具有广泛的心肌保护作用。AK003290是1种在心肌组织中高表达的长链非编码RNA(long noncoding RNA，lncRNA)，在心肌发生损伤时表达下调。本研究旨在探讨丹参酮ⅡA减轻氧糖剥夺(oxygen glucose deprivation，OGD)诱导心肌细胞损伤的机制。方法: 以H9C2大鼠心肌细胞为研究对象，构建OGD损伤模型。采用转染siRNA的方法敲低AK003290的表达。将H9C2细胞分为6组：对照(control)组、丹参酮ⅡA(TAN)组、OGD组、丹参酮ⅡA+OGD(TAN+OGD)组、scrambled siRNA转染+丹参酮ⅡA+OGD(scrambled siRNA+TAN+OGD)组、AK003290 siRNA转染+丹参酮ⅡA+OGD(AK003290 siRNA+TAN+OGD)组。TAN组只用40 μmol/L的丹参酮ⅡA预处理细胞12 h。OGD组只进行OGD处理12 h。TAN+OGD组先用40 μmol/L的丹参酮ⅡA预处理12 h，再行OGD处理12 h。Scrambled siRNA+TAN+OGD组和AK003290 siRNA+TAN+OGD组在转染相应siRNA 24 h后进行后续处理。采用实时反转录PCR(real-time reverse transcription PCR，real-time RT-PCR)检测AK003290的表达，分光光度法检测细胞培养液中乳酸脱氢酶(lactate dehydrogenase，LDH)的水平以反映LDH漏出率，酶联免疫吸附测定(enzyme-linked immunosorbent assay，ELISA)检测细胞培养液中白细胞介素-1β(interleukin-1β，IL-1β)和白细胞介素-18(interleukin-18，IL-18)的含量，蛋白质印迹法检测磷酸化的核因子κB(phospho-nuclear factor-κB，p-NF-κB)的蛋白质表达水平。结果: 与control组比较，OGD组LDH漏出率及细胞培养液中IL-1β和IL-18含量增加，p-NF-κB的蛋白质表达水平上调，差异均有统计学意义(P<0.01或P<0.001)；与OGD组相比，TAN+OGD组LDH漏出率及细胞培养液中IL-1β和IL-18含量减少，p-NF-κB的蛋白质表达水平下调，差异均有统计学意义(P<0.05或P<0.01)。与control组比较，TAN组细胞中AK003290的表达水平明显上调(P<0.01)，OGD组细胞中AK003290的表达水平明显下调(P<0.05)；与OGD组相比，TAN+OGD组细胞中AK003290的表达水平明显上调(P<0.05)。与scrambled siRNA+TAN+OGD组相比，AK003290 siRNA+TAN+OGD组LDH漏出率及细胞培养液中IL-1β和IL-18含量增加，p-NF-κB的蛋白质表达水平上调，差异均有统计学意义(P<0.05或P<0.01)。结论: 丹参酮ⅡA通过上调AK003290抑制NF-κB活性，从而减轻OGD导致的心肌细胞炎症损伤。.

OBJECTIVE: Necroptosis, as a form of regulated cell necrosis, could participate in myocardial oxidative damage. We investigated whether donepezil attenuates H2O2-induced oxidative stress injury and necroptosis in rat cardiomyocytes.
METHODS: H9c2 cells were incubated with H2O2 (final concentration of 1 mM) and then intervened with donepezil at doses of 2.5 and 10 μM. Subsequently, the necroptosis inhibitor necrostatin-1 (Nec-1) was introduced to treat H9c2 cells. For cell function experiments, cell proliferation; the contents of creatine kinase (CK), lactate dehydrogenase (LDH), superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), and malondialdehyde (MDA); the protein and mRNA levels of the necroptosis-related proteins receptor-interacting serine-threonine kinase 3 (RIP3) and mixed lineage kinase-like (MLKL); and calcium ion fluorescence intensity were detected using Cell Counting Kit-8, enzyme-linked immunosorbent assay (ELISA), Western blotting, quantitative reverse transcription polymerase chain reaction, and flow cytometry, respectively.
RESULTS: Cell viability was conspicuously decreased; CK and LDH contents, RIP3 and MLKL expression levels, and MDA production were preeminently elevated; and the production of SOD, CAT, and GSH was prominently reduced under H2O2 stimulation, which were dose-dependently countered by donepezil intervention. Nec-1 decreased the cell necroptosis, oxidative stress, and calcium overload caused by H2O2. However, on the premise of donepezil intervention, the addition of Nec-1 failed to further improve the situation, suggesting that donepezil exerts cardioprotective effects partly by inhibiting RIP3 and MLKL levels.
CONCLUSIONS: Donepezil reduced H2O2-inflicted oxidative stress and necroptosis in cardiomyocytes by suppressing RIP3 and MLKL levels and calcium ion overload.

Myocardial injury is an indicator of poor prognosis in sepsis, whereas propofol has been reported to protect the myocardium. Therefore, the present study investigated the effect of propofol on myocardial injury in sepsis and its mechanism. An in vitro model of myocardial cell injury was established in myocardial H9C2 cells using lipopolysaccharide (LPS). The Cell Counting Kit 8 (CCK8) assay was used to investigate the effect of propofol pretreatment on the viability of normal and LPS-challenged H9C2 cells, whereas the lactate dehydrogenase (LDH) detection kit was used to measure the levels of LDH. The expression levels of LC3 were analyzed using an immunofluorescence assay. Western blotting was performed to analyze the expression levels of autophagy-related proteins. Following treatment with the autophagy inhibitor 3-methyladenine, CCK8 assay, TUNEL assay, western blotting, 2,7-dichlorohydrofluorescein diacetate assay and ELISA were performed to investigate whether propofol exerted its effects on cell viability, apoptosis, oxidative stress and inflammation via autophagy. Moreover, to further explore the regulatory mechanism of propofol in myocardial injury, sirtuin 1 (SIRT1) was knocked down via transfection with small interfering RNA, and SIRT1 protein was inhibited via the addition of the SIRT1 inhibitor EX527. The present study demonstrated that propofol activated autophagy in LPS-induced cardiomyocytes, and reversed the effects of LPS on viability, apoptosis, oxidative stress and the inflammatory response. Moreover, SIRT1 knockdown and inhibition decreased the activation of autophagy and the protective effect of propofol on LPS-induced cardiomyocytes. In conclusion, propofol reduced LPS-induced cardiomyocyte injury by activating SIRT1-mediated autophagy.

Tranilast, a synthetic derivative of a tryptophan metabolite, can be used to treat heart diseases. However, the specific mechanism underlying the effect of tranilast on ischemia-reperfusion (I/R) injury-induced cardiomyocyte apoptosis remains unclear. Therefore, the present study aimed to determine if tranilast could attenuate I/R-induced cardiomyocyte injury. A hypoxia/reoxygenation (H/R) model of H9c2 cardiomyocytes was established to simulate I/R-induced cardiomyocyte injury. The viability, apoptosis, inflammation and oxidative stress in H/R-induced H9c2 cells following treatment with tranilast were evaluated by Cell Counting Kit-8 and TUNEL assay. Commercially available kits were used to detect the levels of inflammatory markers and oxidative stress indicators. In addition, the expression levels of the apoptosis- and nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1)/NF-κB signalling pathway-associated proteins were detected by western blotting. The levels of reactive oxygen species were determined using 2\',7\'-dichlorofluorescin diacetate assay kit. The viability of H9c2 cells was decreased following induction with H/R. However, treatment with tranilast increased viability while decreasing apoptosis, oxidative stress and inflammatory response in H/R-induced H9c2 cells by activating Nrf2/HO-1/NF-κB signalling. Furthermore, treatment with ML-385, an Nrf2 inhibitor, reversed the effects of tranilast on H/R-induced H9c2 cells. In conclusion, the results of the present study suggested that tranilast could attenuate I/R-induced cardiomyocyte injury via the Nrf2/HO-1/NF-κB signalling pathway.

UNASSIGNED: This study sought to explore the role and molecular mechanism of circ_0049271 in hypoxia-reoxygenation (H/R)-induced cardiomyocyte injury.
UNASSIGNED: Significantly upregulated circular ribonucleic acids (circRNAs) in Gene Expression Omnibus (GEO) data sets were identified using a Venn diagram. A H9c2 (rat cardiomyocytes) cell model of acute myocardial infarction (AMI) was induced by 1% H/R. Quantitative reverse transcription-polymerase chain reaction was used to detect the expression levels of circ_0049271, miR-17-3p, and FZD4 in clinical blood samples and cells, and Cell Counting Kit-8 (CCK-8) was used to determine the proliferation rate of the cells in each group. Next, flow cytometry and Western blot were used to evaluate cell apoptosis. Biochemical tests and enzyme-linked immunosorbent assays (ELISAs) were then used to determine the activities/levels of the cell damage markers [i.e., creatine kinase (CK) and lactate dehydrogenase (LDH)], oxidative stress substances [i.e., malondialdehyde (MDA), reactive oxygen species (ROS), and superoxide dismutase (SOD)], and inflammatory factors [i.e., interleukin (IL)-1β, IL-6, and IL-8]. In addition, intermolecular interactions were verified using dual-luciferase reporter and RNA pull-down experiments.
UNASSIGNED: Circ_0049271 was significantly upregulated in both the blood of the AMI patients and the H/R-induced H9c2 cells. The knockdown of circ_0049271 increased the cell proliferation rate, decreased the apoptosis rate, inhibited oxidative stress (ROS and MDA were upregulated, and SOD was downregulated) and inflammatory responses (IL-1, IL-6, and IL-8 were downregulated), and relieved cell damage. However, the overexpression of circ_0049271 promoted H/R-induced H9c2 cell damage. Further experiments showed that miR-17-3p was a target of circ_0049271, and miR-17-3p was negatively correlated with circ_0049271 in the AMI blood samples. Additionally, miR-17-3p was found to target FZD4. A further exploration also revealed that miR-17-3p knockdown or FZD4 overexpression reversed the effects of si-circ_0049271 on the H/R-induced H9c2 cells; that is, miR-17-3p knockdown or FZD4 overexpression promoted H/R-induced injury in the H9c2 cells.
UNASSIGNED: Circ_0049271 promoted cellular function damage (e.g., proliferation inhibition, apoptosis, oxidative stress, and inflammation) in H/R-induced H9c2 cardiomyocytes via the miR-17-3p/FZD4 signaling axis.

Diabetic cardiomyopathy (DCM) is a serious complication of diabetes mellitus that can cause malignant arrhythmia and sudden death and is associated with cardiomyocyte dysfunction induced by hyperglycemia. Emerging evidence has revealed that transfer RNA-derived fragments (tRFs), a novel class of noncoding RNAs, play a crucial role in a variety of pathophysiologic processes, including cell death, cell growth and proliferation. However, it remains unknown whether and how tRFs are involved in cardiomyocyte dysfunction during the progression of DCM. In this study, we found that cardiomyocyte abnormalities were induced by high glucose (HG) treatment, as demonstrated by a decrease in cell viability and autophagy activation as well as an increase in cell death and proinflammatory cytokine release. Moreover, HG treatment resulted in differential expression of tRFs in cardiomyocytes, of which 4 upregulated and 1 downregulated tRFs were observed compared with the control group. The differential expression of 4 upregulated tRFs was primarily involved in cardiac dysfunction-related processes, such as autophagy, AGE-RAGE signaling pathway in diabetic complications, MAPK signaling pathway, insulin signaling pathway, FoxO signaling pathway, insulin resistance and peroxisome pathways based on Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. Furthermore, we found that tRF-5014a, the most significantly upregulated tRF among all tested tRFs, negatively regulated the expression of the autophagy-related protein ATG5. Importantly, inhibition of tRF-5014a not only abolished autophagy inactivation but also attenuated the decrease in cell viability and increase in cell death as well as proinflammatory cytokine release under HG conditions. These findings suggest that tRFs may contribute to HG-induced cardiomyocyte injury during DCM progression.