Hypoxia-induced Cardiomyocyte Research Articles

Impairing Ferroptosis Through the PI3K/Akt/Nrf2 Pathway: The Way for Nerve Growth Factor to Mitigate Hypoxia-induced Cardiomyocyte Damage.

Myocardial infarction (MI) is an acute cardiovascular diseases, distinguished primarily by cardiomyocyte damage due to ischemia and hypoxia. Nerve growth factor (NGF) is paramount in ischemic heart disease, it contributes to maintaining heart function and protecting the heart. Nonetheless, the effects of NGF on cardiomyocyte damage induced by hypoxia and the precise mechanisms involved are still to be elucidated. Utilizing western blot and immunofluorescence methods to quantify the NGF levels in cardiomyocytes (H9C2) of rats after hypoxia. Cell Counting Kit-8 (CCK-8) assay was employed to monitor the dynamic changes in cells vitality. The lactate dehydrogenase (LDH), Fe2+, malondialdehyde (MDA), superoxide dismutase (SOD) and reactive oxygen species (ROS) levels were evaluated by different kits. Moreover, the PI3K/Akt/Nrf2 pathway and ferroptosis-linked protein levels were analyzed using western blotting. In H9C2 cells, exposure to hypoxia for 24 h led to weakened NGF level, as well as lowered cell vitality and SOD activity, but elevated levels of LDH, Fe2+, MDA, and ROS, triggering ferroptosis. Overexpression NGF alleviated the ferroptosis in H9C2 cells caused by hypoxia, while NGF knockdown intensified this process. Additionally, overexpression NGF reinforced heme oxygenase-1 (HO-1) and Nrf2 levels, and Akt and PI3K phosphorylation, whereas NGF silencing produced contrary outcomes. Furthermore, the PI3K/Akt pathway inhibitor negated the elevation in HO-1 and Nrf2 levels mediated by NGF amplification. In contrast, the pathway activator reversed the lowering in Nrf2 and HO-1 levels caused by silencing NGF. This suggested that NGF mediates the activation of Nrf2 through the PI3K/Akt axis. Overall, by mediating the activation of Nrf2 through the PI3K/Akt axis, NGF reduced the damage to H9C2 cells caused by hypoxia and thus hindered ferroptosis.

Circulating CCRR serves as potential novel biomarker for predicting acute myocardial infarction

Abstract 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.

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

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

Circulating microRNA-409-5p and USP7 are associated with left ventricular remodeling in patients with acute myocardial infarction

BackgroundOur previous study demonstrated that microRNA-409-5p (miR-409-5p) and its target ubiquitin-specific protease 7 (USP7) were involved in hypoxia-induced cardiomyocyte injury and ischemic left ventricular remodeling (LVR) in rats. This study aimed to probe into the relationship between plasma miR-409-5p and USP7 levels and LVR and dysfunction in patients with acute myocardial infarction (AMI).MethodsSixty patients with acute myocardial infarction (AMI) and 60 cases with chronic coronary syndrome (CCS) were enrolled. The clinical characteristics, echocardiographic/serum parameters of LVR, and circulating miR-409-5p and USP7 mRNA levels between the two groups and between admission and 6 weeks after discharge were compared. The correlations between circulating miR-409-5p/USP7 levels and serum/echocardiographic parameters were analyzed.ResultsThe demographic characteristics of the AMI group and CCS group were comparable. Patients with AMI admitted to the study displayed significantly higher levels of plasma N-terminal pro-brain natriuretic peptide (NT-proBNP) and growth stimulation expressed gene 2 (ST2), along with a greater left ventricular end-systolic volume (LVESV). Conversely, their left ventricular ejection fraction (LVEF), global longitudinal strain (GLS), and global radial strain (GRS) were significantly lower compared to patients with CCS. These changes were normalized 6 weeks after discharge. Circulating miR-409-5p levels at admission were significantly decreased while circulating USP7 mRNA expression levels were significantly increased in patients with AMI compared with those with CCS (both P < 0.01). However, these changes were restored 6 weeks after discharge (both P < 0.01). Moreover, circulating miR-409-5p and USP7 mRNA levels showed varying correlations with GLS, GRS, LVESV, LVEF, and NT-proBNP in patients with AMI but not in those with CCS. Additionally, circulating miR-409-5p and USP7 levels predicted the incidence of LVR and major adverse cardiovascular events (MACE) after AMI.ConclusionSerum miR-409-5p and USP7 may influence the occurrence and evolution of LVR and left ventricular dysfunction after AMI.

Ling gui shen fu decoction ameliorates cardiac injury in ischemic heart disease rats by regulating ANP32A/HIF2α/HMGB1 signal route

Purpose: To investigate the effect of ling gui shen fu decoction (LGSFD) on cardiac injury and cardiomyocyte apoptosis in rats with ischemic heart disease (IHD), and to elucidate the underlying molecular mechanism. Methods: An IHD rat model was established by performing coronary artery occlusion surgery on the left anterior descending (LAD) of rats. The rats were assigned equally to 5 groups: sham-operated group (sham group), IHD group, IHD + perindopril group, IHD + low- dose LGSFD group (IHD + LGSFD-L group), and IHD + high-dose LGSFD group (IHD+LGSFD-H group). The LGSFD was given via gavage. A hypoxia-induced cardiomyocyte model was established by subjecting H9C2 cells to hypoxia. Then, LGSFD-containing serum or blank serum was used to treat the hypoxic rat cardiomyocytes (H9C2). The severity of cardiac injury and extent of apoptotic changes in cardiomyocytes was determined using hematoxylin-eosin (H&amp;E) staining and TUNEL staining, while immunoblotting was used to measure the protein expressions of ANP32A, p-AKT, AKT, HIF-2α, p-mTOR, mTOR and HMGB1. Results: The cardiac injury of rats in the LGSFD groups was significantly reversed, relative to the IHD group (p &lt; 0.05). Moreover, LGSFD reduced the level of apoptosis in hypoxia- induced H9C2 cells and upregulated the concentrations of ANP32A, p-AKT, HIF-2α and p-mTOR. However, the expression levels of HMGB1 were decreased in the heart tissues of IHD rats and hypoxic H9C2 cells. Silencing of ANP32A with ANP32A siRNA (siANP32A) down- regulated ANP32A, p-AKT, HIF-2α and p-mTOR, but up-regulated apoptosis and expression levels of HMGB1 in hypoxic H9C2 cells. Conclusion: LGSFD ameliorates cardiac injury in IHD rats by inhibiting cardiomyocyte apoptosis via the ANP32A/HIF-2α/HMGB1 axis. Further investigations are recommended into the specific mechanism of LGSFD effect using clinical samples, in order to facilitate its clinical development.

Clinical Value of lncRNA CASC19 in Myocardial Infarction and its Role in Myocardial Infarction-Induced Cardiomyocyte Apoptosis.

To explore the effect of long non-coding RNA cancer susceptibility 19 (lncRNA CASC19) on the activity, apoptosis, and oxidative stress response of cardiomyocytes, so as to assess the clinical relevance and molecular mechanism of CASC19 in myocardial infarction (MI). CASC19 level was determined by using real-time quantitative polymerase chain reaction (RT-qPCR). MI model was constructed using hypoxia induction, and rat cardiomyocytes H9c2 were divided into control group, MI group, MI small interference negative control (MI-si-NC) group, MI-si-CASC19 group, MI-si-CASC19+microRNA-NC (miR-NC) group, and MI-si-CASC19+miR-218-5p inhibitor group. Tetramethylazolium salt colorimetric method and flow cytometry were used to evaluate cell activity and apoptotic capacity. Cellular oxidative stress was evaluated using malondialdehyde and superoxide dismutase kits. The relationship between CASC19 and miR-218-5p was confirmed by using dual-luciferase activity assay. CASC19 levels were enhanced in MI patients and hypoxia-induced cardiomyocytes. Downregulating CASC19 promoted the proliferation, while suppressed apoptosis and oxidative stress in the MI cell model. Moreover, low expression of miR-218-5p reversed the promotion of proliferation and inhibition of apoptosis and oxidative stress in MI cell models by silencing CASC19. Briefly, CASC19 may serve as a diagnostic marker for MI by sponging miR-218-5p to inhibit apoptosis and oxidative stress in cardiomyocytes and promote cell survival.

The Beneficial Effect of the SGLT2 Inhibitor Dapagliflozin in Alleviating Acute Myocardial Infarction-Induced Cardiomyocyte Injury by Increasing the Sirtuin Family SIRT1/SIRT3 and Cascade Signaling.

Sodium-glucose cotransporter-2 inhibitors (SGLT2i) have a variety of cardiovascular and renoprotective effects and have been developed as novel agents for the treatment of heart failure. However, the beneficial mechanisms of SGLT2i on cardiac tissue need to be investigated further. In this study, we established a mouse model of acute myocardial infarction (AMI) using coronary artery constriction surgery and investigated the role of dapagliflozin (DAPA) in protecting cardiomyocytes from hypoxic injury induced by AMI. In vitro experiments were done using hypoxic cultured H9c2 ventricular cells to verify this potential mechanism. Expression of the SIRT family and related genes and proteins was verified by qPCR, Western blotting and immunofluorescence staining, and the intrinsic potential mechanism of cardiomyocyte death due to AMI and hypoxia was comprehensively investigated by RNA sequencing. The RNA sequencing results of cardiomyocytes from AMI mice showed that the SIRT family may be mainly involved in the mechanisms of hypoxia-induced cardiomyocyte death. In vitro hypoxia-induced ventricular cells showed the role of dapagliflozin in conferring resistance to hypoxic injury in cardiomyocytes. It showed that SIRT1/3/6 were downregulated in H9c2 cells in a hypoxic environment, and the addition of dapagliflozin significantly increased the gene and protein expression of SIRT1, 3 and 6. We then verified the underlying mechanisms induced by dapagliflozin in hypoxic cardiomyocytes using RNA-seq, and found that dapagliflozin upregulated the hypoxia-induced gene downregulation, which includes ESRRA, EPAS1, AGTRAP, etc., that associated with SIRTs-related and apoptosis-related signaling to prevent H9c2 cell death. This study provides laboratory data for SGLT2i dapagliflozin treatment of AMI and confirms that dapagliflozin can be used to treat hypoxia-induced cellular necrosis in cardiomyocytes, in which SIRT1 and SIRT3 may play an important role. This opens up further opportunities for SGLT2i in the treatment of heart disease.

The cytoprotective effect of Gymnema inodorum leaf extract against hypoxia-induced cardiomyocytes injury

Ischemic heart disease stands out as a major global contributor to mortality, with the initiation of hypoxia, marked by reduced oxygen availability, disrupting the balance of reactive oxygen species (ROS), leading to cellular injury. Exploring antioxidants derived from medicinal plants is becoming more interesting as a potential alternative treatment, especially for mitigating myocardial injury. Thus, this study aimed to assess the cytoprotective efficacy of Gymnema inodorum leaf extract (GIE) in a rat cardiac myoblast, H9c2, subjected to an in vitro hypoxia. The cell viability, intracellular ROS production and the expression of inflammatory cytokines were quantified, and hypoxia-induced cell morphology changes were observed using confocal fluorescence microscopy. The results showed that GIE notably enhanced cell viability, preserving membrane integrity, when compared with the hypoxic group. Remarkably, GIE significantly reduced hypoxia-induced intracellular ROS production, attributable to its inherent antioxidant properties. Furthermore, GIE significantly reduced interleukin (IL)-1β, interleukin (IL)-6 mRNA expression level and tended to reduce tumor necrosis factor-α (TNF-α) mRNA expression. In conclusion, these findings underscore the potential of GIE in mitigating hypoxia-induced myocardial injury, highlighting its robust antioxidant and anti-inflammatory attributes.

Hypoxia triggers cardiomyocyte apoptosis via regulating the m6A methylation-mediated LncMIAT/miR-708-5p/p53 axis

Long-time hypoxia induced cardiomyocyte apoptosis is an important mechanism of myocardial ischemia (MI) injury. Interestingly, long noncoding RNA myocardial infarction-associated transcript (LncMIAT) has been involved in the regulation of MI injury; however, the underlying mechanism by which LncMIAT affects the progression of hypoxia-induced cardiomyocyte apoptosis remains unclear. In the present study, hypoxia was found to promote cardiomyocyte apoptosis through an increased expression of LncMIAT in vitro. Biological investigations and dual-luciferase gene reporter assay further revealed that LncMIAT was able to bind with miR-708-5p to upregulate the p53-mediated cell death of the cardiomyocytes. Silencing of LncMIAT or overexpression of miR-708-5p led to a significant reduction in p53-mediated cardiomyocyte apoptosis. The methylated RNA immunoprecipitation (MeRIP)-qPCR results showed that hypoxia exerted its effects on LncMIAT through AKLBH5-N6-methyladenosine (m6A) methylation and therefore hypoxia was shown to trigger HL-1 cardiomyocyte apoptosis via the m6A methylation-mediated LncMIAT/miR-708-5p/p53 axis. Silencing of AKLBH5 significantly alleviated the m6A methylation-mediated LncMIAT upregulation and p53-mediated cardiomyocyte apoptosis, while promoted miR-708-5p expression. Taken together, the present study highlighted that LncMIAT could act as a key biological target during hypoxia-induced cardiomyocyte apoptosis. In addition, it was shown that hypoxia could promote cardiomyocyte apoptosis through regulation of the m6A methylation-mediated LncMIAT/miR-708-5p/p53 signaling axis.

Pyroptosis inhibitors MCC950 and VX-765 mitigate myocardial injury by alleviating oxidative stress, inflammation, and apoptosis in acute myocardial hypoxia

Acute myocardial infarction (AMI) is a prevalent cardiovascular disease with high morbidity and mortality rates worldwide. Pyroptosis is an inflammatory form of programmed cell death that has been linked to various pathological conditions. However, its exact contribution to the onset and progression of heart injury in AMI has not yet fully elucidated. Herein, we established mouse AMI model by ligating the left anterior descending artery and performed transcriptome analysis during the early phase of AMI. Mouse HL-1 and human AC-16 cardiomyocytes were subjected to hypoxia to simulate ischemic injury in vitro. Our results revealed a significant activation of the inflammatory response at 3 h post-ligation, as confirmed by RNA sequencing. We identified the occurrence of NLRP3 inflammasome-mediated pyroptosis in the cardiac tissues of human cases with AMI, as well as in mouse models of AMI and hypoxia-induced cardiomyocytes, using immunohistochemistry staining and Western blotting assays. Concurrently, pharmacological inhibition of NLRP3 inflammasome-mediated pyroptosis with MCC950 and VX-765 effectively decreased hypoxia-induced cardiomyocytes injury, while mitigating myocardial oxidative stress, apoptosis and inflammation caused by hypoxia. Moreover, the circulating levels of gasdermin D (GSDMD), the pyroptosis executor, were remarkably elevated in the plasma of mice with early AMI and in the supernatant of hypoxia-exposed cardiomyocytes in a time-dependent manner using ELISA and Western blotting. Furthermore, the change in circulating GSDMD positively correlated with Creatine Kinase-MB (CK-MB) in the plasma of early-stage AMI mouse. In summary, these findings indicated a critical role for NLRP3 inflammasome-mediated pyroptosis in the progression of AMI, the administration of MCC950 and VX-765 may be attractive candidate therapeutic approaches for cardiac injury caused by acute hypoxia or even AMI. Additionally, the circulating GSDMD exhibits potential as a newly diagnostic biomarker for AMI.

MiR-449b-5p Ameliorates Hypoxia-induced Cardiomyocyte Injury through Activating PI3K/AKT Pathway by Targeting BCL2L13.

Recent reports show miR-449b-5p reduces liver and renal ischemia/reperfusion (I/R) injury, but its effects on hypoxia-induced cardiomyocyte injury in ischemic heart disease are still unknown. In this study, AC16 human cardiomyocytes underwent hypoxic conditions for durations of 24, 48, and 72h. We observed that miR-449b-5p expression was significantly downregulated in hypoxic AC16 cardiomyocytes. Elevating the levels of miR-449b-5p in these cells resulted in enhanced cell survival, diminished release of LDH, and a reduction in cell apoptosis and oxidative stress using CCK-8, LDH assays, flow cytometry, TUNEL staining, and various commercial kits. Conversely, reducing miR-449b-5p levels resulted in the opposite effects. Through bioinformatics analysis and luciferase reporter assays, BCL2-like 13 (BCL2L13) was determined to be a direct target of miR-449b-5p. Inhibiting BCL2L13 greatly inhibited hypoxia-induced cell viability loss, LDH release, cell apoptosis, and excessive production of oxidative stress, whereas increasing BCL2L13 negated miR-449b-5p's protective impact in hypoxic AC16 cardiomyocytes. Additionally, miR-449b-5p elevated the levels of the proteins p-PI3K, p-AKT, and Bcl-2, while decreasing Bax expression in hypoxic AC16 cardiomyocytes by targeting BCL2L13. In summary, the research indicates that the protective effects of miR-449b-5p are facilitated through the activation of the PI3K/AKT pathway, which promotes cell survival, and by targeting BCL2L13, which inhibits apoptosis, offering a potential therapeutic strategy for ischemic heart disease by mitigating hypoxia-induced cardiomyocyte injury.

CDC-like kinase 3 deficiency aggravates hypoxia-induced cardiomyocyte apoptosis through AKT signaling pathway.

Hypoxia-induced cardiomyocyte apoptosis is one major pathological change of acute myocardial infarction (AMI), but the underlying mechanism remains unexplored. CDC-like kinase 3 (CLK3) plays crucial roles in cell proliferation, migration and invasion, and nucleotide metabolism, however, the role of CLK3 in AMI, especially hypoxia-induced apoptosis, is largely unknown. The expression of CLK3 was elevated in mouse myocardial infarction (MI) models and neonatal rat ventricular myocytes (NRVMs) under hypoxia. Furthermore, CLK3 knockdown significantly promoted apoptosis and inhibited NRVM survival, while CLK3 overexpression promoted NRVM survival and inhibited apoptosis under hypoxic conditions. Mechanistically, CLK3 regulated the phosphorylation status of AKT, a key player in the regulation of apoptosis. Furthermore, overexpression of AKT rescued hypoxia-induced apoptosis in NRVMs caused by CLK3 deficiency. Taken together, CLK3 deficiency promotes hypoxia-induced cardiomyocyte apoptosis through AKT signaling pathway.

Retracted: LncRNA PVT1 Promotes Hypoxia-Induced Cardiomyocyte Injury by Inhibiting miR-214-3p.

[This retracts the article DOI: 10.1155/2021/4604883.].

Hypoxia-induced stabilization of HIF2A promotes cardiomyocyte proliferation by attenuating DNA damage.

Gradual exposure to a chronic hypoxic environment leads to cardiomyocyte proliferation and improved cardiac function in mouse models through a reduction in oxidative DNA damage. However, the upstream transcriptional events that link chronic hypoxia to DNA damage have remained obscure. We sought to determine whether hypoxia signaling mediated by the hypoxia-inducible factor 1 or 2 (HIF1A or HIF2A) underlies the proliferation phenotype that is induced by chronic hypoxia. We used genetic loss-of-function models using cardiomyocyte-specific HIF1A and HIF2A gene deletions in chronic hypoxia. We additionally characterized a cardiomyocyte-specific HIF2A overexpression mouse model in normoxia during aging and upon injury. We performed transcriptional profiling with RNA-sequencing on cardiac tissue, from which we verified candidates at the protein level. We find that HIF2A - rather than HIF1A - mediates hypoxia-induced cardiomyocyte proliferation. Ectopic, oxygen-insensitive HIF2A expression in cardiomyocytes reveals the cell-autonomous role of HIF2A in cardiomyocyte proliferation. HIF2A overexpression in cardiomyocytes elicits cardiac regeneration and improvement in systolic function after myocardial infarction in adult mice. RNA-sequencing reveals that ectopic HIF2A expression attenuates DNA damage pathways, which was confirmed with immunoblot and immunofluorescence. Our study provides mechanistic insights about a new approach to induce cardiomyocyte renewal and mitigate cardiac injury in the adult mammalian heart. In light of evidence that DNA damage accrues in cardiomyocytes with aging, these findings may help to usher in a new therapeutic approach to overcome such age-related changes and achieve regeneration.

Circ_0020887 Silencing Combats Hypoxic-Induced Cardiomyocyte Injury in an MiR-370-3p/CYP1B1-Dependent Manner.

Targeting circular RNA has been a novel approach to preventing and limiting acute myocardial infarction (AMI). Here, we planned to investigate the role and mechanism of circ_0020887 in AMI progression.Hypoxic injury in human cardiomyocytes (AC16) was measured using cell counting kit-8 assay, 5-ethynyl-2'-deoxyuridine assay, flow cytometry, and colorimetric assay kits. RNA and protein expressions were determined using real-time quantitative PCR and western blotting. Direct interplay between RNAs was determined using dual-luciferase reporter, RNA pull-down, and RIP assays.In the plasma and hypoxia-induced AC16 cells of patients with AMI, circ_0020887 and miR-370-3p were upregulated and downregulated, respectively, concomitant with the upregulation of cytochrome P450 1B1 (CYP1B1). Circ_0020887 interference could inhibit hypoxia-induced AC16 cell apoptosis, oxidative stress, and inflammatory response. Circ_0020887 could sponge miR-370-3p, and miR-370-3p could target CYP1B1. The inhibition effect of circ_0020887 knockdown on hypoxia-induced AC16 cell injury could be reversed by the miR-370-3p inhibitor. Besides, CYP1B1 overexpression also overturned the suppressive effect of miR-370-3p on hypoxia-induced AC16 cell apoptosis, oxidative stress, and inflammatory response.In conclusion, circ_0020887 regulated the miR-370-3p/CYP1B1 axis to regulate hypoxia-induced cardiomyocyte injury, confirming that circ_0020887 might promote cardiomyocyte injury.

Circ-SUZ12 Protects Cardiomyocytes from Hypoxia-Induced Dysfunction Through Upregulating SUZ12 Expression to Activate Wnt/β-catenin Signaling Pathway.

Acute myocardial infarction (AMI) is a common coronary artery disease. This study attempted to reveal the impact of circ-SUZ12 (hsa_circ_0042961) on cardiomyocyte injury after exposure to hypoxia.Circ-SUZ12 was screened out from the GEO dataset GSE169594. RNA expression and protein level were detected by quantitative real-time PCR (qRT-PCR) and Western blot, respectively. The characteristics of circ-SUZ12 were identified by measuring its resistance to Rnase R or actinomycin D (Act D) treatment. CCK-8 and EdU assays were performed to explore the viability of AC16 cells. Cell apoptosis was assessed through TUNEL assay and flow cytometry analysis. Mechanism experiments were performed to investigate the downstream molecular mechanism of circ-SUZ12.Circ-SUZ12 was highly expressed in blood samples of AMI patients in the GEO dataset and lowly expressed in hypoxia-treated cardiomyocytes. Overexpression of circ-SUZ12 reversed hypoxia-induced cardiomyocyte injury. Circ-SUZ12 regulated SUZ12 polycomb repressive complex 2 subunit (SUZ12) expression by recruiting FUS protein. SUZ12 activated the Wnt/β-catenin signaling pathway by increasing the H3K27me3 level in microRNA (miR)-526b-5p promoter to release catenin beta 1 (CTNNB1). CTNNB1 depletion reversed the effect of circ-SUZ12 on the viability and apoptosis of hypoxia-induced cardiomyocytes.Circ-SUZ12 protects cardiomyocytes from hypoxia-induced dysfunction through upregulating SUZ12 expression to activate the Wnt/β-catenin signaling pathway.

Errata: Silencing of Hsa_circ_0055440 Alleviates Hypoxia-Induced Cardiomyocyte Injury by Regulating the MiR-499b-5p/ACSL1 Axis.

Several errors (shown with underlines) in the following list appeared in the article entitled "Silencing of Hsa_circ_0055440 Alleviates Hypoxia-Induced Cardiomyocyte Injury by Regulating the MiR-499b-5p/ACSL1 Axis" by Lianhua Yan, Haijun Qi, and Wei Zhou (Vol. 64 No.2, 274-282, 2023).

Circular RNA ANKIB1 alleviates hypoxia-induced cardiomyocyte injury by modulating miR-452-5p/SLC7A11 axis.

Acute myocardial infarction (AMI) is a common cardiovascular disease worldwide. Circular RNAs (circRNAs) have been shown to exert essential roles in the progression of AMI. However, it remains unclear whether circANKIB1 protects cardiomyocytes from hypoxia-induced injury. The aim of the study was to elucidate the function and mechanisms of circANKIB1 in AMI. The expression of RNA was estimated using a quantitative real-time polymerase chain reaction (qPCR) assay, and the level of protein was determined with the use of western blot analysis. Methyl thiazolyl tetrazolium (MTT) assay was introduced to test cell viability, and a terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay was used to detect apoptosis. The relative levels of ferrous ion (Fe2+), reactive oxygen species (ROS) and malondialdehyde (MDA) were measured with their corresponding detection kits. The potential target of circANKIB1 and miR-452-5p was predicted using the StarBase database and verified by employing a dual luciferase reporter assay. This study showed a significant decrease in circANKIB1 in hypoxia-treated H9c2 cells. Hypoxic exposure significantly reduced the viability of H9c2 cells and the expression of GPX4, and increased the content of Fe2+, ROS and MDA. These effects were reversed by the overexpression of circANKIB1. Additionally, miR-452-5p was found to be a direct target of circANKIB1, and the miR-452-5p mimic significantly eliminated the protective effect of circANKIB1 overexpression in hypoxia-induced cells. In addition, miR-452-5p could bind to SLC7A11 and negatively regulate its expression. The knockdown of SLC7A11 abolished the effect of circANKIB1 overexpression on hypoxia-induced cardiomyocyte injury. This investigation revealed for the first time that circANKIB1 regulated signaling of the miR-452-5p/SLC7A11 axis, thereby ameliorating hypoxia-induced cardiomyocyte injury. These findings suggest that circANKIB1 might be a useful adjunct in the treatment of AMI.

CVD-associated SNPs with regulatory potential reveal novel non-coding disease genes

BackgroundCardiovascular diseases (CVDs) are the leading cause of death worldwide. Genome-wide association studies (GWAS) have identified many single nucleotide polymorphisms (SNPs) appearing in non-coding genomic regions in CVDs. The SNPs may alter gene expression by modifying transcription factor (TF) binding sites and lead to functional consequences in cardiovascular traits or diseases. To understand the underlying molecular mechanisms, it is crucial to identify which variations are involved and how they affect TF binding.MethodsThe SNEEP (SNP exploration and analysis using epigenomics data) pipeline was used to identify regulatory SNPs, which alter the binding behavior of TFs and link GWAS SNPs to their potential target genes for six CVDs. The human-induced pluripotent stem cells derived cardiomyocytes (hiPSC-CMs), monoculture cardiac organoids (MCOs) and self-organized cardiac organoids (SCOs) were used in the study. Gene expression, cardiomyocyte size and cardiac contractility were assessed.ResultsBy using our integrative computational pipeline, we identified 1905 regulatory SNPs in CVD GWAS data. These were associated with hundreds of genes, half of them non-coding RNAs (ncRNAs), suggesting novel CVD genes. We experimentally tested 40 CVD-associated non-coding RNAs, among them RP11-98F14.11, RPL23AP92, IGBP1P1, and CTD-2383I20.1, which were upregulated in hiPSC-CMs, MCOs and SCOs under hypoxic conditions. Further experiments showed that IGBP1P1 depletion rescued expression of hypertrophic marker genes, reduced hypoxia-induced cardiomyocyte size and improved hypoxia-reduced cardiac contractility in hiPSC-CMs and MCOs.ConclusionsIGBP1P1 is a novel ncRNA with key regulatory functions in modulating cardiomyocyte size and cardiac function in our disease models. Our data suggest ncRNA IGBP1P1 as a potential therapeutic target to improve cardiac function in CVDs.

Panax notoginseng saponins inhibits NLRP3 inflammasome-mediated pyroptosis by downregulating lncRNA-ANRIL in cardiorenal syndrome type 4

ObjectiveCardiorenal syndrome type 4 (CRS4) is a complication of chronic kidney disease. Panax notoginseng saponins (PNS) have been confirmed to be efficient in cardiovascular diseases. Our study aimed to explore the therapeutic role and mechanism of PNS in CRS4.MethodsCRS4 model rats and hypoxia-induced cardiomyocytes were treated with PNS, with and without pyroptosis inhibitor VX765 and ANRIL overexpression plasmids. Cardiac function and cardiorenal function biomarkers levels were measured by echocardiography and ELISA, respectively. Cardiac fibrosis was detected by Masson staining. Cell viability was determined by cell counting kit-8 and flow cytometry. Expression of fibrosis-related genes (COL-I, COL-III, TGF-β, α-SMA) and ANRIL was examined using RT-qPCR. Pyroptosis-related protein levels of NLRP3, ASC, IL-1β, TGF-β1, GSDMD-N, and caspase-1 were measured by western blotting or immunofluorescence staining.ResultsPNS improved cardiac function, and inhibited cardiac fibrosis and pyroptosis in a dose-dependent manner in model rats and injured H9c2 cells (p < 0.01). The expression of fibrosis-related genes (COL-I, COL-III, TGF-β, α-SMA) and pyroptosis-related proteins (NLRP3, ASC, IL-1β, TGF-β1, GSDMD-N, and caspase-1) was inhibited by PNS in injured cardiac tissues and cells (p < 0.01). Additionally, ANRIL was upregulated in model rats and injured cells, but PNS reduced its expression in a dose-dependent manner (p < 0.05). Additionally, the inhibitory effect of PNS on pyroptosis in injured H9c2 cells was enhanced by VX765 and reversed by ANRIL overexpression, respectively (p < 0.05).ConclusionPNS inhibits pyroptosis by downregulating lncRNA-ANRIL in CRS4.