NEAT1 regulates VSMC differentiation and calcification in as long noncoding RNA NEAT1 enhances phenotypic and osteogenic switching of vascular smooth muscle cells in atherosclerosis via scaffolding EZH2.

Atherosclerosis (AS) is a significant contributor to cardio-cerebrovascular ischemia diseases, resulting in high mortality rates worldwide. During AS, vascular smooth muscle cells (VSMCs) play a crucial role in plaque formation by undergoing phenotypic and osteogenic switching. Long noncoding RNA nuclear paraspeckle assembly transcript 1 (NEAT1) has previously been identified as a nuclear regulator that promotes tumorigenesis and metastasis, but its role in regulating VSMCs in AS remains unclear. Our study aimed to investigate the biological functions and specific mechanisms of NEAT1 in regulating VSMCs in AS. We found that NEAT1 was upregulated in the aortas of AS mouse models and dedifferentiated primary VSMCs. Silencing NEAT1 in vitro attenuated the proliferation, migration, and osteogenic differentiation of VSMCs, while NEAT1 overexpression had the opposite effect. Furthermore, NEAT1 promoted VSMC osteogenic differentiation and vascular calcification in both in vivo and in vitro vascular calcification models. We also discovered that NEAT1 directly activates enhancer of zeste homolog 2 (EZH2), an epigenetic enzyme that suppresses the expression of senescence- and antimigration-related genes, by translocating it into the nucleus. CUT&Tag assay revealed that NEAT1 guides EZH2 to the promoters of senescence-related genes (P16, P21, and TIMP3), methylating local histones to reduce their transcription. Our findings suggest that NEAT1 functions in AS by modulating the epigenetic function of EZH2, which enhances the proliferation, migration, and osteogenic differentiation of VSMCs. This study provides new insights into the molecular mechanisms underlying the pathogenesis of AS and highlights the potential of NEAT1 as a therapeutic target of AS.NEW & NOTEWORTHY Our study demonstrates that the upregulation of long noncoding RNA nuclear paraspeckle assembly transcript 1 (NEAT1) promotes proliferation and migration during phenotypic switching of vascular smooth muscle cells in atherosclerosis. We also provide in vivo and in vitro evidence that NEAT1 accelerates vascular calcification. Our findings identified the direct interaction between enhancer of zeste homolog 2 (EZH2) and NEAT1 during atherosclerosis. NEAT1 is necessary for EZH2 to translocate from the cytoplasm to the nucleus, where EZH2 epigenetically inhibits the expression of genes related to senescence and antimigration.

Long noncoding RNA NEAT1 promotes cardiac fibrosis in heart failure through increased recruitment of EZH2 to the Smad7 promoter region.

Cardiac fibrosis, a well-known major pathological process that ultimately leads to heart failure, has attracted increasing attention and focus in recent years. A large amount of research indicates that long noncoding RNAs (lncRNAs) play an important role in cardiac fibrosis, but little is known about the specific function and mechanism of the lncRNA NEAT1 in the progression of cardiac fibrosis to heart failure. In the present study, we have demonstrated that the lncRNA NEAT1 is upregulated in patients with heart failure. Similarly, the expression of Neat1 was also increased in the left ventricular tissue of transverse aortic constriction (TAC) surgery mice and cardiac fibroblasts treated with TGF-ß1. Further, gain-of-function and loss-of-function experiments showed that silencing of Neat1 attenuated cardiac fibrosis, while overexpression of Neat1 with adenovirus significantly aggravated the in vitro progression of fibrosis. With regard to the underlying mechanism, our experiments showed that Neat1 recruited EZH2 to the promoter region of Smad7 through physical binding of EZH2 to the promoter region, as a result of which Smad7 expression was inhibited and the progression of cardiac fibrosis was ultimately exacerbated. We found that the introduction of shNeat1 carried by adeno-associated virus-9 significantly ameliorated cardiac fibrosis and dysfunction caused by TAC surgery in mice. Overall, our study findings demonstrate that the lncRNA Neat1 accelerates the progression of cardiac fibrosis and dysfunction by recruiting EZH2 to suppress Smad7 expression. Thus, NEAT1 may serve as a target for the treatment of cardiac fibrosis.

Cadherin-11 deficiency mitigates high-fat diet-induced inflammatory atrial remodeling and vulnerability to atrial fibrillation.

Atrial fibrillation (AF) is the most common cardiac arrhythmia nowadays. The occurrence of AF is closely associated with obesity. Cadherin-11 (Cad-11), as a member of the cadherin family, can make a contribution to diet-induced obesity and it will be informative to know whether Cad-11 exerts its effects on atrial remodeling and AF vulnerability in a diet-induced obesity model. In this study, we demonstrated that the expression of Cad-11 was significantly upregulated in the left atrium of AF patients with obesity and mice following 16 weeks of high-fat diet (HFD) feeding. Further confirmed that Cad-11 could regulate the activity of atrial fibroblasts by participating in inducing proinflammatory cytokines production. At animal levels, we found that although there was a lack of statistical difference in body weight, Cad-11-/- mice could markedly improve impaired glucose tolerance and hyperlipidemia. Adverse atrial structural remodeling, including atrial enlargement, inflammation, and fibrosis provoked by HFD feeding were mitigated in Cad-11-/- mice. Mechanistically, Cad-11 activated mitogen-activated protein kinases and nuclear factor-κB for interleukin-6 production in atrial fibroblasts that may contribute to the atrial fibrosis process in obesity-related AF, suggesting Cad-11 might be a new therapeutic target for obesity-related AF.

[Protective effect of ginsenoside Rg_1 on hypoxia/reoxygenation injury and its mechanism].

This project aimed to explore the protective effect of ginsenoside Rg_1 on hypoxia/reoxygenation(H/R)-induced H9 c2 cardiomyocyte injury and its underlying signaling pathway. The H/R model of H9 c2 cardiomyocytes was established and then the cells were divided into different treatment groups. CCK-8(cell counting kit-8) was used to detect the activity of cardiomyocytes; Brdu assay was used to detect the proliferation of H9 c2 cells; the caspase-3 activity was tested, and then the protein expression was assessed by Western blot. Flow cytometry was used to evaluate the apoptosis level of cardiomyocytes. Ginsenoside Rg_1 inhibited H/R-induced cardiomyocyte apoptosis and caspase-3 activity, promoted nuclear transcription of nuclear factor erythroid-2 related factor 2(Nrf2), and enhanced the expression of the downstream heme oxygenase-1(HO-1). Ginsenoside Rg_1 could increase Nrf2 nuclear transcription and HO-1 expression with the increase of concentration(10, 20, 40, 60 µmol·L~(-1)). However, the protective effect of ginsenoside Rg_1 on cardiomyocytes was significantly weakened after the transfection of Nrf2-siRNA. Ginsenoside Rg_1 could protect cardiomyocytes by activating the Nrf2/HO-1 pathway.

MFGE8 attenuates Ang-II-induced atrial fibrosis and vulnerability to atrial fibrillation through inhibition of TGF-ß1/Smad2/3 pathway.

Atrial fibrillation (AF) is characterized by potentiated growth of atrial fibroblasts and excessive deposition of the extracellular matrix. Atrial fibrosis has emerged as a hallmark of atrial structural remodeling linked to AF. Nonetheless, the specific mechanism underlying the progression of atrial fibrosis to AF is still largely unknown. MFGE8 (milk fat globule-EGF factor 8) is a soluble glycoprotein associated with many human diseases. Recently, a number of studies revealed that MFGE8 plays a crucial role in heart disease. Yet, MFGE8 regulation and function in the process of atrial fibrosis and vulnerability to AF remain unexplored. In this study, we found that the expression of MFGE8 was downregulated in the atriums of patients with AF compared with individuals without AF. In addition, the expression of MFGE8 was lower in atriums of angiotensin II (Ang-II)-stimulated rats as compared with the sham group. In vitro, silencing of MFGE8 by small interfering RNA significantly increased Ang-II-induced atrial fibrosis, whereas administration of recombinant human MFGE8 (rhMFGE8) attenuated the atrial fibrosis. Moreover, we found that the activated TGF-ß1/Smad2/3 pathway after Ang-II treatment was significantly potentiated by the MFGE8 knockdown but inhibited by rhMFGE8 in vitro. Inhibition of integrin ß3 which is the receptor for MFGE8, suppressed the TGF-ß1/Smad2/3 activating effects of the MFGE8 knockdown in Ang-II-treated rat atrial fibroblasts. Finally, we administered rhMFGE8 to rats; it attenuated atrial fibrosis and remodeling and further reduced AF vulnerability induced by Ang-II, indicating that MFGE8 might have the potential both as a novel biomarker and as a therapeutic target in atrial fibrosis and AF.

MFGE8 is down-regulated in cardiac fibrosis and attenuates endothelial-mesenchymal transition through Smad2/3-Snail signalling pathway.

Endothelial-mesenchymal transition (EndMT) is a major source of transformed cardiac fibroblasts, which is reported to play a key role in cardiac fibrosis (CF), a pathogenesis of cardiovascular diseases such as heart failure, myocardial infarction and atrial fibrillation. Nonetheless, the specific mechanism underlying the progression of EndMT to CF is still largely unknown. In this study, we aimed to investigate the role of milk fat globule-EGF factor 8 (MFGE8), a kind of soluble glycoprotein, in TGF-ß1-induced EndMT. In animal experiments, the expression of MFGE8 was found down-regulated in the left ventricle and aorta of rats after transverse aortic constriction (TAC) compared with the sham group, especially in endothelial cells (ECs). In in vitro cultured ECs, silencing MFGE8 with small interfering RNA (siRNA) was found to promote the process of TGF-ß1-induced EndMT, whereas administration of recombinant human MFGE8 (rh-MFGE8) attenuated the process. Moreover, activated Smad2/3 signalling pathway after TGF-ß1 treatment and EndMT-related transcription factors, such as Snail, Twist and Slug, was potentiated by MFGE8 knock-down but inhibited by rh-MFGE8. In conclusion, our experiments indicate that MFGE8 might play a protective role in TGF-ß1-induced EndMT and might be a potential therapeutic target for cardiac fibrosis.

NLRC5 deficiency ameliorates cardiac fibrosis in diabetic cardiomyopathy by regulating EndMT through Smad2/3 signaling pathway.

Diabetic cardiomyopathy (DCM) is one of the main causes of heart failure in patients with diabetes. Cardiac fibrosis caused by endothelial mesenchymal transformation (EndMT) plays an important role in the pathogenesis of DCM. NLRC5 is a recently discovered immune and inflammatory regulatory molecule in the NOD-like receptor family, and is involved in organ fibrosis. In this study, we found that the expression of NLRC5 was up-regulated in endothelial cells (ECs) and cardiac fibroblasts (CFs) in diabetes models both in vivo and in vitro. NLRC5 knockdown significantly inhibited high glucose-induced EndMT. In addition, NLRC5 deficiency inhibited the expression of phosphorylated Smad2/3 and the activation of EndMT-related transcription factors in ECs induced by high glucose. However, the effect of NLRC5 deficiency on CFs was not obvious. In summary, our results suggest that NLRC5 deficiency ameliorates cardiac fibrosis in DCM by inhibiting EndMT through Smad2/3 signaling pathway and related transcription factors. NLRC5 is likely to be a biomarker and therapeutic target of cardiac fibrosis in diabetic cardiomyopathy.

Pyrrolidine Dithiocarbamate Enhances the Cytotoxic Effect of Arsenic Trioxide on Acute Promyelocytic Leukemia Cells.

BACKGROUND: More than 95% patients with acute promyelocytic leukemia (APL) carry the PML-RARα fusion oncoprotein. Arsenic trioxide (ATO) is an efficacious therapeutic agent for APL, and the mechanism involves the binding with PML and degradation of PML-RARα protein. Pyrrolidine dithiocarbamate (PDTC) demonstrates the function of facilitating the cytotoxic effect of ATO. PURPOSE: To investigate whether PDTC is potential to enhance the cytotoxic effect of ATO to APL cells by acting on PML-RARα oncoproteins. METHODS: Inhibitory effects of drugs on cell viability were examined by CCK-8 test, and apoptosis was evaluated by flow cytometry. Western blotting and immunofluorescence assays were used to explore the mechanism. RESULTS: PDTC improved the effect of ATO on inhibiting proliferation of NB4 cells in vitro. Further, PDTC-ATO promoted apoptosis and cell cycle arrest in NB4 cells. The expression of caspase- 3 and Bcl-2 was reduced in PDTC-ATO-treated NB4 cells, while cleaved caspase-3 and Bax was up-regulated. Furthermore, less PML-RARα expression were found in PDTC-ATO-treated NB4 cells than that in NB4 cells treated with ATO singly. Laser confocal microscopy showed that protein colocalization of PML and RARα was disrupted more significantly by PDTC-ATO treatment than that with ATO monotherapy. CONCLUSION: In conclusion, PDTC enhanced the cytotoxic effect of ATO on APL, and the mechanism was, at least in part, related to the promotion of ATO-induced degradation of PML-RARα fusion protein via forming a complex PDTC-ATO.

BMP6 knockdown enhances cardiac fibrosis in a mouse myocardial infarction model by upregulating AP-1/CEMIP expression.

BACKGROUND: The cardiac repair process following a myocardial infarction is a key factor in patient prognosis. In this repair process, cardiac fibrosis takes a critically important role. Among those featured genes for fibrosis, transforming growth factor beta (TGF-ß) is known to be involved in the fibrosis in various organs. And bone morphogenetic protein (BMP)6 belongs to the TGF-ß superfamily. Although BMPs are known to play exclusive roles in cardiac repair processes, the character of BMP6 in cardiac remodelling remains unclear. PURPOSE: This study aimed to investigate how BMP6 functioned in cardiac fibrosis following myocardial infarction (MI). RESULTS: In this paper, we demonstrated that BMP6 expression was upregulated after myocardial infarction in wild-type (WT) mice. Furthermore, BMP6-/- mice showed a more significant decline in cardiac function and lower survival curves after MI. An enlarged infarct area, increased fibrosis and more pronounced inflammatory infiltration were observed in BMP6-/- mice compared to WT mice. The expression of collagen I, collagen III and α-SMA was increased in BMP6-/- mice. In vitro, through gain-of-function and loss-of-function experiments, it was demonstrated that BMP6 decreases collagen secretion in fibroblasts. Mechanistically, knocking down BMP6 promoted AP-1 phosphorylation, which in turn promotes CEMIP expression, led to an acceleration in the progression of cardiac fibrosis. Finally, it was found that rhBMP6 would alleviate ventricular remodelling abnormalities after myocardial infarction. CONCLUSION: Therefore, BMP6 may be a novel molecular target for improving myocardial fibrosis and cardiac function after myocardial infarction.

Upregulation of microRNA-34a enhances myocardial ischemia-reperfusion injury via the mitochondrial apoptotic pathway.

Mitochondrial oxidative injury can result in many cardiovascular diseases including cardiac ischemia-reperfusion (I/R) injury. This study was designed to investigate whether microRNA-34a (miR-34a) influences cardiac I/R or hypoxia/reoxygenation (H/R) injury by regulating the mitochondrial apoptotic pathway from oxidative injury.In vivo, myocardial infarction size was examined by Evan blue/TTC staining. Apoptosis was assessed by TUNEL assay. Heart function was measured by echocardiography. Lactate dehydrogenase (LDH) and creatine kinase (CK) were evaluated. In vitro, H9c2 cardiomyocytes were exposed to H/R stimulation. Cell viability was assessed by the CCK-8 assay and apoptosis was detected by Annexin V/PI staining. Mitochondrial superoxide, mitochondrial membrane potential (MMP) and ATP production was evaluated by detection kits, and related proteins were detected by western blotting analysis. We observed that the level of miR-34a was significantly upregulated in I/R rats compared to the sham group. Injection of adenovirus inhibiting miR-34a into the left ventricular anterior wall improved heart function and decreased I/R injury. H9c2 cardiomyocytes exposed to H/R stimulation displayed an obvious increase in miR-34a expression. In addition, miR-34a inhibitor alleviated, whereas miR-34a mimic aggravated H/R-induced mitochondrial injury. Bcl-2 was identified as a target gene of miR-34a by dual-luciferase reporter gene detection. Knockdown of Bcl-2 abolished the cardioprotection of the miR-34a inhibitor in H9c2 cells. In summary,our study demonstrates that inhibition of miR-34a exhibits therapeutic potential in treatment of myocardial I/R injury by restraining mitochondrial apoptosis.

ADAMTS8 Promotes Cardiac Fibrosis Partly Through Activating EGFR Dependent Pathway.

Myocardial infarction or pressure overload leads to cardiac fibrosis, the leading cause of heart failure. ADAMTS8 (A disintegrin and metalloproteinase with thrombospondin motifs 8) has been reported to be involved in many fibrosis-related diseases. However, the specific role of ADAMTS8 in cardiac fibrosis caused by myocardial infarction or pressure overload is yet unclear. The present study aimed to explore the function of ADAMTS8 in cardiac fibrosis and its underlying mechanism. ADAMTS8 expression was significantly increased in patients with dilated cardiomyopathy; its expression myocardial infarction and TAC rat models was also increased, accompanied by increased expression of α-SMA and Collagen1. Adenovirus-mediated overexpression of ADAMTS8 through cardiac in situ injection aggravated cardiac fibrosis and impaired cardiac function in the myocardial infarction rat model. Furthermore, in vitro studies revealed that ADAMTS8 promoted the activation of cardiac fibroblasts; ADAMTS8 acted as a paracrine mediator allowing for cardiomyocytes and fibroblasts to communicate indirectly. Our findings showed that ADAMTS8 could damage the mitochondrial function of cardiac fibroblasts and then activate the PI3K-Akt pathway and MAPK pathways, promoting up-regulation of YAP expression, with EGFR upstream of this pathway. This study systematically revealed the pro-fibrosis effect of ADAMTS8 in cardiac fibrosis and explored its potential role as a therapeutic target for the treatment of cardiac fibrosis and heart failure.

LncRNA Gaplinc promotes the pyroptosis of vascular endothelial cells through SP1 binding to enhance NLRP3 transcription in atherosclerosis.

Pyroptosis, characterized by activation of the Nod-like receptor family pyrin domain containing 3 (NLRP3) inflammasome and its downstream effector inflammatory factors, has been shown to play a crucial role in atherosclerosis development. Long noncoding RNAs (lncRNAs) are involved in the progression of pyroptosis. However, the role and mechanism of the novel lncRNA gastric adenocarcinoma associated, positive CD44 regulator (Gaplinc), in endothelial cell pyroptosis during atherosclerosis development remain unexplored. Bioinformatics was performed to evaluate dysregulated lncRNAs in atherosclerotic mice fed a high-fat diet. The effect of Gaplinc on atherosclerosis progression in vivo was assessed via Oil Red O staining and fluorescence in situ hybridization. Its function in oxidized low-density lipoprotein (ox-LDL)-induced pyroptosis of endothelial cells was determined through ectopic expression. Additionally, RNA pull-down and immunoprecipitation (RIP) assays were performed to determine Gaplinc and transcription factor SP1 interactions. Then the pyroptosis pathway proteins were analyzed via immunofluorescence and western blotting. We found that lncRNA Gaplinc was highly expressed in ox-LDL-induced endothelial cells as well as in the plaque and plasma of high-fat diet-treated ApoE-/- mice. Gaplinc silencing significantly inhibited endothelial cell pyroptosis and atherosclerotic plaque formation. Mechanistically, Gaplinc could interact with SP1 to bind to the NLRP3 promoter and upregulate the target gene expression of NLRP3, facilitating endothelial cell pyroptosis and atherosclerotic plaque enlargement in high- fat diet-fed mice. In conclusion, our results revealed the underlying mechanism of the lncRNA Gaplinc /SP1/NLRP3 axis in endothelial cell pyroptosis, which may provide new potential targets for the treatment of atherosclerosis.

Circ-ADAM9 targeting PTEN and ATG7 promotes autophagy and apoptosis of diabetic endothelial progenitor cells by sponging mir-20a-5p.

Dysfunction of endothelial progenitor cells (EPCs) is a key factor in vascular complications of diabetes mellitus. Although the roles of microRNAs and circular RNAs in regulating cell functions have been thoroughly studied, their role in regulating autophagy and apoptosis of EPCs remains to be elucidated. This study investigated the roles of mir-20a-5p and its predicted target circ-ADAM9 in EPCs treated with high glucose (30 mM) and in a diabetic mouse hind limb ischemia model. It is found that Mir-20a-5p inhibited autophagy and apoptosis of EPCs induced by high-concentration glucose. Further, mir-20a-5p could inhibit the expression of PTEN and ATG7 in EPCs, and promote the phosphorylation of AKT and mTOR proteins under high-glucose condition. Investigation of the underlying mechanism revealed that circ-ADAM9, as a miRNA sponges of mir-20a-5p, promoted autophagy and apoptosis of EPCs induced by high-concentration glucose. Circ-ADAM9 upregulated PTEN and ATG7 in interaction with mir-20a-5p, and inhibited the phosphorylation of AKT and mTOR to aggravate autophagy and apoptosis of EPCs under high glucose. In addition, silencing of circ-ADAM9 increased microvessel formation in the hind limbs of diabetic mice. Our findings disclose a novel autophagy/apoptosis-regulatory pathway that is composed of mir-20a-5p, circ-ADAM9, PTEN, and ATG7. Circ-ADAM9 is a potential novel target for regulating the function of diabetic EPCs and angiogenesis.

Activation of CXCR7 alleviates cardiac insufficiency after myocardial infarction by promoting angiogenesis and reducing apoptosis.

Angiogenesis is an important pathway for revascularization of ischemic tissues after acute myocardial infarction (AMI). It is unclear what role CXCR7 plays in angiogenesis in the ischemic area after AMI, although some researchers have shown that the activation of CXCR7 protectsthe heart under those conditions. Here, we hypothesize that the activation of CXCR7 promotes angiogenesis, reduces cell apoptosis and alleviates cardiac deficiency after AMI. C57BL/6 J mice were subjected to AMI and treated with TC14012 (10 mg/kg) for 24 days. HUVECs were cultured in a hypoxic (2% O2) environment to generate a model of hypoxia. CXCR7 was knocked down in HUVECs by sh-CXCR7 transfection, and CXCR7 was activated by TC14012 (30 µM) treatment. The results showed that CXCR7 was downregulated in infarcted heart tissue and hypoxic HUVECs. The global activation of CXCR7 may alleviate the decrease in cardiac function indexes - (ejection fraction and fraction shortening), and reduce infarct size after AMI.. Moreover, CXCR7 activation has been shown to enhance the level of angiogenesis in ischemic heart tissue. In vitro, hypoxia-induced angiogenic functional loss and apoptosis are aggravated by CXCR7 knockdown in HUVECs. Both angiogenic impairment and cell apoptosis are rescued by CXCR7 activation. In conclusion, the present study indicates that activation of CXCR7 plays an important protective role for ischemic cells in hypoxic endothelial cells and AMI model mice by promoting angiogenesis and reducing apoptosis, which suggests that CXCR7 may be a potential therapeutic target to rescue the ischemic myocardium..

Delphinidin attenuates pathological cardiac hypertrophy via the AMPK/NOX/MAPK signaling pathway.

Reactive oxygen species (ROS) play a pivotal role in the development of pathological cardiac hypertrophy. Delphinidin, a natural flavonoid, was reported to exert marked antioxidative effects. Therefore, we investigated whether delphinidin ameliorates pathological cardiac hypertrophy via inhibiting oxidative stress. In this study, male C57BL/6 mice were treated with DMSO or delphinidin after surgery. Neonatal rat cardiomyocytes (NRCMs) were treated with angiotensin II (Ang II) and delphinidin in vitro. Eighteen-month-old mice were administered delphinidin to investigate the effect of delphinidin on aging-related cardiac hypertrophy. Through analyses of hypertrophic cardiomyocyte growth, fibrosis and cardiac function, delphinidin was demonstrated to confer resistance to aging- and transverse aortic constriction (TAC)-induced cardiac hypertrophy in vivo and attenuate Ang II-induced cardiomyocyte hypertrophy in vitro by significantly suppressing hypertrophic growth and the deposition of fibrosis. Mechanistically, delphinidin reduced ROS accumulation upon Ang II stimulation through the direct activation of AMP-activated protein kinase (AMPK) and subsequent inhibition of the activity of Rac1 and expression of p47phox. In addition, excessive levels of ERK1/2, P38 and JNK1/2 phosphorylation induced by oxidative stress were abrogated by delphinidin. Delphinidin was conclusively shown to repress pathological cardiac hypertrophy by modulating oxidative stress through the AMPK/NADPH oxidase (NOX)/mitogen-activated protein kinase (MAPK) signaling pathway.