Glycogen synthase kinase 3 beta inhibitor SB216763 improves Kir2.1 expression after myocardia infraction in rats

LncRNA AC125982.2 regulates apoptosis of cardiomyocytes through mir-450b-3p/ATG4B axis in a rat model with myocardial infarction

BACKGROUND

The occurrence and disability of myocardial infarction (MI) are on the rise globally, making it a significant contributor to cardiovascular mortality. Irreversible myocardial apoptosis plays a crucial role in causing MI. Long non-coding RNAs (LncRNAs) are key regulators of the cardiac remodeling process. Therefore, it is necessary to explore the effect of LncRNAs on cardiomyocyte apoptosis in MI.

METHODS

The rat-MI model was constructed, LncRNA-Seq and qPCR analyses were used to determine differentially expressed genes obtained from heart tissue of rats in the MI and sham groups. The miRanda software was used to predict the binding sites of LncRNA-miRNA and miRNA-mRNA, which were futhrer verified by dual luciferase assay. The LncRNA-miRNA-apoptosis pathway was further validated using hypoxia-exposed primary cardiomyocytes.

RESULTS

Compared to the sham group, 412 LncRNAs were upregulated and 501 LncRNAs were downregulated in MI-rat heart tissues. Among them, LncRNA AC125982.2 was most significantly upregulated in MI-rat heart tissues and hypoxic cardiomyocytes. Knockdown of AC125982.2 and ATG4B expression reversed hypoxia-induced apoptosis. In addition, transfection of mir-450b-3p inhibitor attenuated the protective effect of AC125982.2 knockdown. Moreover, we found that AC125982.2 modulated ATG4B expression by acting as a sponge for miR-450b-3p.

CONCLUSION

Upregulated AC125982.2 expression regulates ATG4B by sponging miR-450b-3p, promoting cardiomyocyte apoptosis and contributing to rat MI development.

ALKBH5 inhibitors as a potential treatment strategy in heart failure-inferences from gene expression profiling

Heart Failure (HF) is a complex clinical syndrome in which the heart is unable to provide enough blood flow to meet metabolic needs and lacks efficient venous return. HF is a major risk factor for morbidity and mortality with cardiovascular diseases globally. Despite enormous research, the molecular markers relevant to disease prognosis and management remain not well understood. Here, we analyzed the whole transcriptomes of 18 failing hearts and 15 non-failing hearts (predominantly of Caucasian origin), by applying the standard in silico tools. The analyses revealed novel gene-markers including ALKBH5 of mRNA demethylation and KMT2E of histone modification processes, significantly over-expressed in the HF compared with the non-failing hearts (FDR < 0.05). To validate the over-expression of ALKBH5, we determined the global m6A level in hypoxic H9c2 cells using a dot blot assay. The global m6A level was found markedly lower in the hypoxic H9c2 cells than in the control cells. Additionally, the expression of ALKBH5 in the H9c2 cells was quantified by the qPCR and found to be 1.18 times higher at 12 h (p < 0.05), and 1.67 times higher at 24 h of hypoxia (p < 0.01) compared with the control cells, indicating a likely role of ALKBH5 in the failing cardiac cells. Furthermore, we identified several compounds through the virtual screening of 11,272 drug-like molecules of the ZINC15 database to inhibit the ALKBH5 in a molecular docking process. Collectively, the study revealed novel markers potentially involved in the pathophysiology of HF and suggested plausible therapeutic molecules for the management of the disease.

Non-coding RNAs as biomarkers of myocardial infarction

Non-coding RNAs (ncRNAs) encompass a family of ubiquitous RNA molecules that lack protein-coding potential and have tissue-specific expression. A significant body of evidence indicates that ncRNA's aberrant expression plays a critical role in disease onset and development. NcRNAs' biochemical characteristics such as disease-associated concentration changes, structural stability, and high abundance in body fluids make them promising prognostic and diagnostic biomarkers. Myocardial infarction (MI) is a leading cause of mortality worldwide. Acute myocardial infarction (AMI), the term in use to describe MI's early phase, is generally diagnosed by physical examination, electrocardiogram (ECG), and the presence of specific biomarkers. In this regard, compared to standard MI biomarkers, such as the cardiac troponin isoforms (cTnT & cTnI) and the Creatinine Kinase (CK), ncRNAs appears to provide better sensitivity and specificity, ensuring a rapid and correct diagnosis, an earlier treatment, and consequently a good prognosis for the patients. This review aims to summarize and discuss the most promising and recent data on the potential clinical use of circulating ncRNAs as MI biomarkers. Specifically, we focused primarily on miRNAs and lncRNAs, highlighting their significant specificity and sensitivity, discussing their limitations, and suggesting possible overcoming approaches.

The caspase-1 inhibitor VX765 upregulates connexin 43 expression and improves cell-cell communication after myocardial infarction via suppressing the IL-1β/p38 MAPK pathway

Connexin 43 (Cx43) is the most important protein in the gap junction channel between cardiomyocytes. Abnormalities of Cx43 change the conduction velocity and direction of cardiomyocytes, leading to reentry and conduction block of the myocardium, thereby causing arrhythmia. It has been shown that IL-1β reduces the expression of Cx43 in astrocytes and cardiomyocytes in vitro. However, whether caspase-1 and IL-1β affect connexin 43 after myocardial infarction (MI) is uncertain. In this study we investigated the effects of VX765, a caspase-1 inhibitor, on the expression of Cx43 and cell-to-cell communication after MI. Rats were treated with VX765 (16 mg/kg, i.v.) 1 h before the left anterior descending artery (LAD) ligation, and then once daily for 7 days. The ischemic heart was collected for histochemical analysis and Western blot analysis. We showed that VX765 treatment significantly decreased the infarct area, and alleviated cardiac dysfunction and remodeling by suppressing the NLRP3 inflammasome/caspase-1/IL-1β expression in the heart after MI. In addition, VX765 treatment markedly raised Cx43 levels in the heart after MI. In vitro experiments were conducted in rat cardiac myocytes (RCMs) stimulated with the supernatant from LPS/ATP-treated rat cardiac fibroblasts (RCFs). Pretreatment of the RCFs with VX765 (25 μM) reversed the downregulation of Cx43 expression in RCMs and significantly improved intercellular communication detected using a scrape-loading/dye transfer assay. We revealed that VX765 suppressed the activation of p38 MAPK signaling in the heart tissue after MI as well as in RCMs stimulated with the supernatant from LPS/ATP-treated RCFs. Taken together, these data show that the caspase-1 inhibitor VX765 upregulates Cx43 expression and improves cell-to-cell communication in rat heart after MI via suppressing the IL-1β/p38 MAPK pathway.

Targeting Glycogen Synthase Kinase 3 Beta Regulates CD47 Expression After Myocardial Infarction in Rats via the NF-κB Signaling Pathway

The aim of this study was to investigate the effects of the GSK-3β/NF-κB pathway on integrin-associated protein (CD47) expression after myocardial infarction (MI) in rats. An MI Sprague Dawley rat model was established by ligating the left anterior descending coronary artery. The rats were divided into three groups: Sham, MI, and SB + MI (SB216763) groups. Immunohistochemistry was used to observe the changes in cardiac morphology. A significant reduction in the sizes of fibrotic scars was observed in the SB + MI group compared to that in the MI group. SB216763 decreased the mRNA and protein expression of CD47 and NF-κB during MI. Primary rat cardiomyocytes (RCMs) and the H9c2 cell line were used to establish in vitro hypoxia models. Quantitative real-time PCR and western blotting analyses were conducted to detect mRNA and protein expression levels of CD47 and NF-κB and apoptosis-related proteins, respectively. Apoptosis of hypoxic cells was assessed using flow cytometry. SB216763 reduced the protein expression of CD47 and NF-κB in RCMs and H9c2 cells under hypoxic conditions for 12 h, and alleviated hypoxia-induced apoptosis. SN50 (an NF-κB inhibitor) also decreased CD47 protein expression in RCMs and H9c2 cells under hypoxic conditions for 12 h and protected cells from apoptosis. GSK-3β upregulates CD47 expression in cardiac tissues after MI by activating NF-κB, which in turn leads to myocardial cell damage and apoptosis.