Overexpressing of the GIPC1 protects against pathological cardiac remodelling.

OBJECTIVE: Pathological cardiac remodelling, including cardiac hypertrophy and fibrosis, is a key pathological process in the development of heart failure. However, effective therapeutic approaches are limited. The ß-adrenergic receptors are pivotal signalling molecules in regulating cardiac function. G-alpha interacting protein (GAIP)-interacting protein, C-terminus 1 (GIPC1) is a multifunctional scaffold protein that directly binds to the C-terminus of ß1-adrenergic receptor (ß1-adrenergic receptor). However, little is known about its roles in heart function. Therefore, we investigated the role of GIPC1 in cardiac remodelling and its underlying molecular mechanisms. METHODS: Pathological cardiac remodelling in mice was established via intraperitoneal injection of isoprenaline for 14 d or transverse aortic constriction surgery for 8 weeks. Myh6-driving cardiomyocyte-specific GIPC1 conditional knockout (GIPC1 cKO) mice and adeno-associated virus 9 (AAV9)-mediated GIPC1 overexpression mice were used. The effect of GIPC1 on cardiac remodelling was assessed using echocardiographic, histological, and biochemical analyses. RESULTS: GIPC1 expression was consistently reduced in the cardiac remodelling model. GIPC1 cKO mice exhibited spontaneous abnormalities, including cardiac hypertrophy, fibrosis, and systolic dysfunction. In contrast, AAV9-mediated GIPC1 overexpression in the heart attenuated isoproterenol-induced pathological cardiac remodelling in mice. Mechanistically, GIPC1 interacted with the ß1-adrenergic receptor and stabilised its expression by preventing its ubiquitination and degradation, maintaining the balance of ß1-adrenergic receptor/ß2-adrenergic receptor, and inhibiting hyperactivation of the mitogen-activated protein kinase signalling pathway. CONCLUSIONS: These results suggested that GIPC1 plays a cardioprotective role and is a promising therapeutic target for the treatment of cardiac remodelling and heart failure.

miR-135 protects against atrial fibrillation by suppressing intracellular calcium-mediated NLRP3 inflammasome activation.

Atrial fibrillation (AF), one of the most common types of arrhythmias, is associated with high morbidity and mortality, seriously endangering human health. Inflammation is closely associated with AF development. Activation of the nucleotide-binding domain-like receptor protein 3 (NLRP3) inflammasome in cardiomyocytes has been shown to promote AF progression. Here, we demonstrate the effect of miR-135 on NLRP3 inflammasome and study the cardioprotective role of miR-135 in AF. We observed that overexpression of miR-135 in mice reduced the AF incidence and duration, and inhibited both excessive activation of NLRP3 inflammasome and the increased intracellular calcium release during AF. However, the inhibitory effect of miR-135 on AF was partly abolished in the presence of a specific agonist of the calcium-sensing receptor (CaSR). We showed in the present study that miR-135 has a protective effect against AF by suppressing intracellular calcium-mediated NLRP3 inflammasome activation, suggesting the potential of miR-135 as a therapeutic agent in the treatment of AF.

Daming capsule protects against myocardial infarction by promoting mitophagy via the SIRT1/AMPK signaling pathway.

Myocardial infarction (MI) is a myocardial injury caused by coronary thrombosis or persistent ischemia and hypoxia. Due to its high morbidity and mortality, a safer and more effective treatment strategy is urgently needed. Daming capsule (DMC), a hypolipidemic drug, reportedly exerts cardioprotective effects in clinical and basic research, although its protective mechanism remains unknown. To investigate the mechanism underlying DMC-mediated improvement of cardiac function post-MI, C57/BL6 mice subjected to coronary artery ligation were administered DMC for 4 weeks. Our data demonstrated that DMC significantly improved cardiac structure and function compared to the saline group. Moreover, DMC inhibited inflammatory response and oxidative stress and improved mitochondrial structure and function in MI mice and hypoxia-stressed cardiomyocytes. Next, our research proved that DMC increased the expression of mitophagy receptor NLRX1. Interestingly, with the administration of DMC and siNLRX1, NLRX1 expression, mitochondria and lysosome colocalization, and mitochondrial membrane potential decreased, while mitochondrial ROS accumulation increased, suggesting that DMC promoted mitophagy to improve mitochondrial function via NLRX1 regulation. Further analysis showed that DMC activated the SIRT1/AMPK signaling pathway in vivo and in vitro. Our data showed that SIRT1 knockdown downregulated NLRX1 expression, leading to structural damage and functional impairment in mitochondria, as well as increased oxidative stress, inflammatory response, and decreased cardiac function in MI mice. Collectively, our findings reveal that DMC improves cardiac function post-MI by increasing mitophagy and inhibiting oxidative stress and inflammotory response in cardiomyocytes through the SIRT1/AMPK signaling pathway.

The whole transcriptome analysis and the circRNA-lncRNA network construction in arsenic trioxide-treated mice myocardium.

BACKGROUND/AIMS: Arsenic trioxide (ATO) is an effective anti-cancer drug. Nonetheless, it possesses cardiotoxic effects which limit its clinical application. The present study aims to elucidate the molecular basis of ATO-induced cardiotoxicity through using whole transcriptome analysis. METHODS: The whole transcriptome in ATO-treated mice myocardium was analyzed using RNA sequencing technique. These results were confirmed by real-time PCR. The lncRNA-mRNA and circRNA-mRNA co-expression networks were constructed. Finally, a circRNA-lncRNA co-regulated competing endogenous RNA (ceRNA) network was constructed. GO and KEGG pathway analyses were performed. The expression levels of Txnip and Spp1 in ATO-treated neonatal mouse cardiomyocytes were validated by real-time PCR. RESULTS: A total of 113 mRNAs, 159 lncRNAs, 35 miRNAs, and 94 circRNAs were differentially expressed in ATO-treated mice myocardium. A lncRNA-circRNA co-regulation network was constructed. Function annotation revealed that aberrantly expressed genes may be enriched in the 'Wnt signaling pathway', 'Hippo signaling pathway', 'Notch signaling pathway', etc. Finally, the expression levels of Txnip and Spp1 were validated in ATO-treated cardiomyocytes, which was in accordance with the RNA-sequencing results. CONCLUSION: ATO altered coding and noncoding RNA profiles in myocardium of mice. The ATO-related lncRNA-circRNA co-regulation network was constructed. Genes in the co-regulation network are likely to play important roles in the cardiotoxicity of ATO. This study provides new insights into the prevention and treatment of ATO-induced cardiotoxicity.

Loss of m6A methyltransferase METTL3 promotes heart regeneration and repair after myocardial injury.

AIMS: N6-Methyladenosine (m6A), one of the important epigenitic modifications, is very commom in messenger RNAs (mRNAs) of eukaryotes, and has been involved in various diseases. However, the role of m6A modification in heart regeneration after injury remains unclear. The study was conducted to investigate whether targeting methyltransferase-like 3 (METTL3) could replenish the loss of cardiomyocytes (CMs) and improve cardiac function after myocardial infarction (MI). METHODS AND RESULTS: METTL3 knockout mouse line was generated. A series of functional experiments were carried out and the molecular mechanism was further explored. We identified that METTL3, a methyltransferase of m6A methylation, is upregulated in mouse hearts after birth, which is the opposite of the changes in CMs proliferation. Furthermore, both METTL3 heterozygous knockout mice and administration of METTL3 shRNA adenovirus in mice exhibited CMs cell cycle re-entered, infract size decreased and cardiac function improved after MI. Mechanically, the silencing of METTL3 promoted CMs proliferation by reducing primary miR-143 (pri-miR-143) m6A modificaiton, thereby inhibiting the pri-miR-143 into mature miR-143-3p. Moreover, we found that miR-143-3p has targeting effects on Yap and Ctnnd1 so as to regulate CMs proliferation. CONCLUSION: METTL3 deficiency contributes to heart regeneration after MI via METTL3-pri-miR-143-(miR-143)-Yap/Ctnnd1 axis. This study provides new insights into the significance of RNA m6A modification in heart regeneration.

Ranolazine protects against diabetic cardiomyopathy by activating the NOTCH1/NRG1 pathway.

AIMS: Diabetic cardiomyopathy (DCM) is a common diabetes complication that can cause arrhythmia, heart failure, and even sudden death. Ranolazine is an antianginal agent used to treat chronic stable angina and has been demonstrated as an effective treatment for many cardiovascular diseases. However, the mechanism by which ranolazine alleviates DCM is unclear, motivating this study investigating the effects of ranolazine in DCM. MATERIALS AND METHODS: DCM rats were treated with one of three doses of ranolazine (10, 30, and 90 mg/kg/day) for 12 weeks. B-cell lymphoma 2 (Bcl-2), Bcl-2 associated X protein (Bax), cysteinyl aspartate specific proteinase-3 (Caspase-3), Notch homolog 1 (NOTCH1), and Neuregulin 1 (NRG1) expression was assayed using western blot and qRT-PCR. Cardiac changes were assayed using echocardiography, CT, HE staining, and Masson's trichrome staining. TUNEL staining and flow cytometry were used to detect cell apoptosis. NOTCH1 inhibitor (DAPT) was used to explore the mechanism of ranolazine. KEY FINDINGS: Compared with the DCM group, the ranolazine groups had no obvious weight loss and significantly decreased blood glucose levels. Ranolazine prevented diabetes-caused cardiac injury. Ranolazine also decreased the number of apoptotic cells and altered the expression of apoptosis-related mRNAs and proteins. Ranolazine-induced NOTCH1 activated NRG1 and inhibited the downstream apoptosis-related pathway, while DAPT partially inhibited ranolazine-induced NOTCH1 and NRG1 expression. SIGNIFICANCE: To our knowledge, this study is the first to demonstrate that ranolazine protects against DCM-induced apoptosis by activating the NOTCH1/NRG1 signaling pathway. Moreover, our study identified new mechanisms involved in DCM.

Downregulation of miR-200a protects cardiomyocyte against apoptosis.

BACKGROUND/AIMS: Acute myocardial infarction (AMI) is a major clinical manifestation of ischemic heart disease and represents a significant cause of morbidity and mortality. However, key regulators in the pathogenesis of ischemic heart disease remain controversial. The present study was designed to investigate the involvement of miR-200a and its related mechanism in AMI. METHODS: Left coronary artery (LCA) ligation was conducted to induce an AMI mouse model. The infarct size was measured by TTC staining. H2O2 was used to induce an AMI model in vitro. miR-200a mimics, anti-miR-200a antisense oligodeoxyribonucleotides (AMO-200a), as well as corresponding negative controls were transfected into cardiomyocytes to observe the effect of miR-200a. Flow cytometry was used to detect cell apoptosis. Real-time PCR, immunofluorescence and western blot assays were used to evaluate gene expression at RNA or protein levels, respectively. RESULTS: Apoptosis was activated in AMI models. The expression of miR-200a was upregulated both in the peri-infarcted region of mice myocardium and H2O2-treated cardiomyocytes. The co-administration of AMO-200a decreased the number of apoptosis cells and altered the expression of apoptosis related proteins. Interestingly, bioinformatics analysis results revealed that miR-200a could bind to the 3'-untranslated regions (3'-UTR) of Fus mRNA. In addition, the expression of Fus was downregulated in the AMI mouse models and in H2O2-treated cardiomyocytes. The alteration of miR-200a negatively regulated Fus expression in cardiomyocytes. Also, the protective effect of AMO-200a was observed through its regulation of Fus. CONCLUSION: MiR-200a-dependent apoptosis signaling pathway plays an important role in the pathogenesis of AMI injury and could be an exciting potential therapeutic target.

The Capsid Protein VP1 of Coxsackievirus B Induces Cell Cycle Arrest by Up-Regulating Heat Shock Protein 70.

Manipulating cell cycle is one of the common strategies used by viruses to generate favorable cellular environment to facilitate viral replication. Coxsackievirus B (CVB) is one of the major viral pathogens of human myocarditis and cardiomyopathy. Because of its small genome, CVB depends on cellular machineries for productive replication. However, how the structural and non-structural components of CVB would manipulate cell cycle is not clearly understood. In this study, we demonstrated that the capsid protein VP1 of CVB type 3 (CVB3) induced cell cycle arrest at G1 phase. G1 arrest was the result of the decrease level of cyclin E and the accumulation of p27Kip1. Study on the gene expression profile of the cells expressing VP1 showed that the expression of both heat shock protein 70-1 (Hsp70-1) and Hsp70-2 was significantly up-regulated. Knockdown of Hsp70 resulted in the increased level of cyclin E and the reduction of p27Kip1. We further demonstrated that the phosphorylation of the heat shock factor 1, which directly promotes the expression of Hsp70, was also increased in the cell expressing VP1. Moreover, we show that CVB3 infection also induced G1 arrest, likely due to dysregulating Hsp70, cyclin E, and p27, while knockdown of Hsp70 dramatically inhibited viral replication. Cell cycle arrest at G1 phase facilitated CVB3 infection, since viral replication in the cells synchronized at G1 phase dramatically increased. Taken together, this study demonstrates that the VP1 of CVB3 induces cell cycle arrest at G1 phase through up-regulating Hsp70. Our findings suggest that the capsid protein VP1 of CVB is capable of manipulating cellular activities during viral infection.

Anthocyanin is involved in the activation of pyroptosis in oral squamous cell carcinoma.

BACKGROUND: The anti-carcinogenic effects of anthocyanin are well documented. Oral squamous cell carcinoma is one of the most common and lethal cancer types due to its high degree of malignancy and poor prognosis. The main purpose of the current study was to investigate the potential inhibitory effects of anthocyanin on oral squamous cell carcinoma and identify effective targets for therapy. METHODS: Cell viability was measured using cell counting kit-8 (CCK8). Cell migration and invasion abilities were determined using scratch-wound and Transwell invasion assays, respectively. mRNA and protein expression patterns of nucleotide-binding oligomerization domain-like receptor pyrin domain containing 3 (NLRP3), caspase-1 and IL-1ß were detected using qRT-PCR, immunofluorescence and western blot. The gasdermin D (GSDMD) level was determined via confocal microscopy and western blot. RESULTS: Anthocyanin reduced the viability of oral squamous cell carcinoma cells and inhibited migration and invasion abilities. Simultaneously, activation of pyroptosis was associated with enhanced expression of NLRP3, caspase-1, and IL-1ß. Upon administration of caspase-1 inhibitors, anthocyanin-activated pyroptosis was suppressed and cell viability, migration, and invasion rates concomitantly enhanced. CONCLUSION: Anthocyanin promotes the death of oral squamous cell carcinoma cells through activation of pyroptosis and inhibits tumor progression.

Caspase-1 regulate AngII-induced cardiomyocyte hypertrophy via upregulation of IL-1ß.

Cardiac hypertrophy is a compensatory response to stress or stimuli, which results in arrhythmia and heart failure. Although multiple molecular mechanisms have been identified, cardiac hypertrophy is still difficult to treat. Pyroptosis is a caspase-1 dependent pro-inflammatory programmed cell death. Caspase-1 is involved in various types of diseases, including hepatic injury, cancers, and diabetes related complications. However, the exact role of caspase-1 in cardiac hypertrophy is yet to be discovered. The present study aimed to explore the possible role of caspase-1 in pathogenesis of cardiac hypertrophy. We established cardiac hypertrophy models both in vivo and in vitro to detect the expression of caspase-1 and IL-1ß. The results showed that caspase-1 and IL-1ß expression levels were significantly upregulated during cardiac hypertrophy. Subsequently, caspase-1 inhibitor was co-administered with angiotensin II (Ang II) in cardiomyocytes to observe whether it could attenuate cardiac hypertrophy. Results showed that caspase-1 attenuated the pro-hypertrophic effect of Ang II, which was related to the downregulation of caspase-1 and IL-1ß. In conclusion, our results provide a novel evidence that caspase-1 mediated pyroptosis is involved in cardiac hypertrophy, and the inhibition of caspase-1 will offer a therapeutic potential against cardiac hypertrophy.

Melatonin protects bone marrow mesenchymal stem cells against iron overload-induced aberrant differentiation and senescence.

Bone marrow mesenchymal stem cells (BMSCs) are an expandable population of stem cells which can differentiate into osteoblasts, chondrocytes and adipocytes. Dysfunction of BMSCs in response to pathological stimuli contributes to bone diseases. Melatonin, a hormone secreted from pineal gland, has been proved to be an important mediator in bone formation and mineralization. The aim of this study was to investigate whether melatonin protected against iron overload-induced dysfunction of BMSCs and its underlying mechanisms. Here, we found that iron overload induced by ferric ammonium citrate (FAC) caused irregularly morphological changes and markedly reduced the viability in BMSCs. Consistently, osteogenic differentiation of BMSCs was significantly inhibited by iron overload, but melatonin treatment rescued osteogenic differentiation of BMSCs. Furthermore, exposure to FAC led to the senescence in BMSCs, which was attenuated by melatonin as well. Meanwhile, melatonin was able to counter the reduction in cell proliferation by iron overload in BMSCs. In addition, protective effects of melatonin on iron overload-induced dysfunction of BMSCs were abolished by its inhibitor luzindole. Also, melatonin protected BMSCs against iron overload-induced ROS accumulation and membrane potential depolarization. Further study uncovered that melatonin inhibited the upregulation of p53, ERK and p38 protein expressions in BMSCs with iron overload. Collectively, melatonin plays a protective role in iron overload-induced osteogenic differentiation dysfunction and senescence through blocking ROS accumulation and p53/ERK/p38 activation.