A20 (TNFAIP3) alleviates viral myocarditis through ADAR1/miR-1a-3p-dependent regulation

Hsa-circ-ACSL1 Enhances Apoptosis and Autophagy in Myocarditis Cardiomyocytes Through the miR-7-5p/XBP1 Axis

BACKGROUND

Viral myocarditis (VMC) is a common cardiovascular disease, and circular RNAs (circRNAs) have been identified to play an important role in the pathophysiology of cardiovascular disease. However, the clinical significance, biological functions, and regulatory mechanisms of circRNAs in VMC remain poorly understood. Therefore, this study explored the biological functions and regulatory mechanisms of circ-ACSL1 in VMC.

METHODS

The animal and cell models of VMC were established by infecting BABL/C mice and interleukin-2 cells with coxsackievirus B3 (CVB3). Pro-inflammatory factors, markers of myocardial injury, apoptosis, and autophagy were detected to evaluate the degree of myocardial inflammation and myocardial injury after altering circ-ACSL1, microRNA-7-5p (miR-7-5p), and X-box binding protein 1 (XBP1) expression alone or in combination.

RESULTS

Knocking down circ-ACSL1 could inhibit inflammation, autophagy, and apoptosis in VMC animals and cells. Mechanistically, circ-ACSL1 targeted miR-7-5p to regulate the downstream target XBP1. In addition, depleting miR-7-5p rescued the therapeutic effect of depleting circ-ACSL1. Overexpression of circ-ACSL1 aggravated VMC; however, this effect was saved by knocking down XBP1.

CONCLUSION

By competitively absorbing miR-7-5p, circ-ACSL1 increases XBP1 expression and aggravates myocardial inflammation. Meaningfully, VMC treatment may benefit from circ-ACSL1 as a potential biomarker for precise diagnosis and as a potential therapeutic target.

Adenosine deaminase acting on RNA 1 (ADAR1) as crucial regulators in cardiovascular diseases: structures, pathogenesis, and potential therapeutic approach

Cardiovascular diseases (CVDs) are a group of diseases that have a major impact on global health and are the leading cause of death. A large number of chemical base modifications in ribonucleic acid (RNA) are associated with cardiovascular diseases. A variety of ribonucleic acid modifications exist in cells, among which adenosine deaminase-dependent modification is one of the most common ribonucleic acid modifications. Adenosine deaminase acting on ribonucleic acid 1 (Adenosine deaminase acting on RNA 1) is a widely expressed double-stranded ribonucleic acid adenosine deaminase that forms inosine (A-to-I) by catalyzing the deamination of adenosine at specific sites of the target ribonucleic acid. In this review, we provide a comprehensive overview of the structure of Adenosine deaminase acting on RNA 1 and summarize the regulatory mechanisms of ADAR1-mediated ribonucleic acid editing in cardiovascular diseases, indicating Adenosine deaminase acting on RNA 1 as a promising therapeutic target in cardiovascular diseases.

A Model of iPSC-Derived Macrophages with TNFAIP3 Overexpression Reveals the Peculiarities of TNFAIP3 Protein Expression and Function in Human Macrophages

Macrophages play a crucial role in the development and control of inflammation. Understanding the mechanisms balancing macrophage inflammatory activity is important to develop new strategies for treating inflammation-related diseases. TNF-α-induced protein 3 (TNFAIP3, A20) is a negative regulator of intracellular inflammatory cascades; its deficiency induces hyper-inflammatory reactions. Whether A20 overexpression can dampen macrophage inflammatory response remains unclear. Here, we generated human-induced pluripotent stem cells with tetracycline-inducible A20 expression and differentiated them into macrophages (A20-iMacs). A20-iMacs displayed morphology, phenotype, and phagocytic activity typical of macrophages, and they displayed upregulated A20 expression in response to doxycycline. A20 overexpression dampened the A20-iMac response to TNF-α, as shown by a decreased expression of IL1B and IL6 mRNA. A dynamic analysis of A20 expression following the generation of A20-iMacs and control iMacs showed that the expression declined in iMacs and that iMacs expressed a lower molecular weight form of the A20 protein (~70 kDa) compared with less differentiated cells (~90 kDa). A low-level expression of A20 and the predominance of a low-molecular-weight A20 form were also characteristic of monocyte-derived macrophages. The study for the first time developed a model for generating macrophages with an inducible expression of a target gene and identified the peculiarities of A20 expression in macrophages that likely underlie macrophage preparedness for inflammatory reactivity. It also suggested the possibility of mitigating inflammatory macrophage responses via A20 overexpression.

Coxsackievirus B3 infection induces glycolysis to facilitate viral replication

Coxsackievirus B3 (CVB3) is a leading cause of viral myocarditis, but no effective treatment strategy against CVB3 is available. Viruses lack an inherent metabolic system and thus depend on host cellular metabolism for their benefit. In this study, we observed that CVB3 enhanced glycolysis in H9c2 rat cardiomyocytes and HL-1 mouse cardiomyocytes. Therefore, three key glycolytic enzymes, namely, hexokinase 2 (HK2), muscle phosphofructokinase (PFKM), and pyruvate kinase M2 (PKM2), were measured in CVB3-infected H9c2 and HL-1 cells. Expression levels of HK2 and PFKM, but not PKM2, were increased in CVB3-infected H9c2 cells. All three key glycolytic enzymes showed elevated expression in CVB3-infected HL-1 cells. To further investigate this, we used 2 deoxyglucose, sodium citrate, and shikonin as glycolysis inhibitors for HK2, PFKM, and PKM2, respectively. Glycolysis inhibitors significantly reduced CVB3 replication, while the glycolysis enhancer dramatically promoted it. In addition, glycolysis inhibitors decreased autophagy and accelerated autophagosome degradation. The autophagy inducer eliminated partial inhibition effects of glycolysis inhibitors on CVB3 replication. These results demonstrate that CVB3 infection enhances glycolysis and thus benefits viral replication.

Enhanced pathogenicity by up-regulation of A20 after avian leukemia subgroup a virus infection

Avian leukemia virus subgroup A (ALV-A) infection slows chicken growth, immunosuppression, and tumor occurrence, causing economic loss to the poultry industry. According to previous findings, A20 has a dual role in promoting and inhibiting tumor formation but has rarely been studied in avians. In this study, A20 overexpression and shRNA interference recombinant adenoviruses were constructed and inoculated into chicken embryos, and ALV-A (rHB2015012) was inoculated into 1-day-old chicks. Analysis of body weight, organ index, detoxification, antibody production, organ toxin load, and Pathological observation revealed that A20 overexpression could enhance ALV-A pathogenicity. This study lays the foundation for subsequent exploration of the A20-mediated tumorigenic mechanism of ALV-A.

Melatonin Alters the miRNA Transcriptome of Inflammasome Activation in Murine Microglial Cells

Systemic inflammation can have devastating effects on the central nervous system via its resident immune cells, the microglia. One of the primary mediators of this inflammation is inflammasomes, multiprotein complexes that trigger a release of inflammatory proteins when activated. Melatonin, a hormone with anti-inflammatory effects, is an attractive candidate for suppressing such inflammation. In this study, we have investigated how melatonin alters the microRNA (miRNA) transcriptome of microglial cells. For that purpose, we have performed RNA sequencing on a lipopolysaccharide and adenosine triphosphate (LPS + ATP) induced NLR family pyrin domain containing 3 (NLRP3) inflammasome activation model in the N9 mouse microglial cell line, with and without melatonin pre-treatment. We have identified 136 differentially expressed miRNAs in cells exposed to LPS + ATP compared to controls and 10 differentially expressed miRNAs in melatonin pre-treated cells compared to the inflammasome group. We have identified miR-155-3p as a miRNA that is upregulated with inflammasome activation and downregulated with melatonin treatment. We further confirmed this pattern of miR-155-3p expression in the brains of mice injected intraperitoneally with LPS. Moreover, an overexpression study with miRNA-155-3p mimic supported the idea that the protective effects of melatonin in NLRP3 inflammasome activation are partly associated with miRNA-155-3p inhibition.