MicroRNA regulation of unfolded protein response transcription factor XBP1 in the progression of cardiac hypertrophy and heart failure in vivo

Delivery of miR-214 via extracellular vesicles downregulates Xbp1 expression and pro-inflammatory cytokine genes in macrophages

Aim

Tumor-infiltrating macrophages are tumor-promoting and show activation of the unfolded protein response (UPR). The transcription factor X-box binding protein 1 (XBP1) is a conserved element of the UPR. Upon activation, the UPR mediates the transcriptional activation of pro-inflammatory cytokines and immune suppressive factors, hence contributing to immune dysregulation in the tumor microenvironment (TME). miR-214 is a short non-coding miRNA that targets the 3'-UTR of the Xbp1 transcript. Here, we tested a new method to efficiently deliver miR-214 to macrophages as a potential new therapeutic approach.

Methods

We generated miR-214-laden extracellular vesicles (iEV-214) in a murine B cell and demonstrated that iEV-214 were enriched in miR-214 between 1,500 - 2,000 fold relative to control iEVs.

Results

Bone marrow-derived macrophages (BMDM) treated with iEV-214 for 24 h underwent a specific enrichment in miR-214, suggesting transfer of the miR-214 payload from the iEVs to macrophages. iEV-214 treatment of BMDM markedly reduced (> 50%) Xbp1 transcription under endoplasmic reticulum stress conditions compared to controls. Immune-related genes downstream of XBP1s (Il-6, Il-23p19, and Arg1) were also reduced by 69%, 51%, and 34%, respectively.

Conclusions

Together, these data permit to conclude that iEV-214 are an efficient strategy to downregulate the expression of Xbp1 mRNA and downstream genes in macrophages. We propose miRNA-laden iEVs are a new approach to target macrophages and control immune dysregulation in the TME.

(+)-Lipoic acid reduces mitochondrial unfolded protein response and attenuates oxidative stress and aging in an in vitro model of non-alcoholic fatty liver disease

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is a liver disorder characterized by the ac-cumulation of fat in hepatocytes without alcohol consumption. Mitochondrial dysfunction and endoplasmic reticulum (ER) stress play significant roles in NAFLD pathogenesis. The unfolded protein response in mitochondria (UPRmt) is an adaptive mechanism that aims to restore mitochondrial protein homeostasis and mitigate cellular stress. This study aimed to investigate the effects of ( +)-Lipoic acid (ALA) on UPRmt, inflammation, and oxidative stress in an in vitro model of NAFLD using HepG2 cells treated with palmitic acid and oleic acid to induce steatosis.

RESULTS

Treatment with palmitic and oleic acids increased UPRmt-related proteins HSP90 and HSP60 (heat shock protein), and decreased CLPP (caseinolytic protease P), indicating ER stress activation. ALA treatment at 1 μM and 5 μM restored UPRmt-related protein levels. PA:OA (palmitic acid:oleic acid)-induced ER stress markers IRE1α (Inositol requiring enzyme-1), CHOP (C/EBP Homologous Protein), BIP (Binding Immunoglobulin Protein), and BAX (Bcl-2-associated X protein) were significantly reduced by ALA treatment. ALA also enhanced ER-mediated protein glycosylation and reduced oxidative stress, as evidenced by decreased GPX1 (Glutathione peroxidase 1), GSTP1 (glutathione S-transferase pi 1), and GSR (glutathione-disulfide reductase) expression and increased GSH (Glutathione) levels, and improved cellular senescence as shown by the markers β-galactosidase, γH2Ax and Klotho-beta.

CONCLUSIONS

In conclusion, ALA ameliorated ER stress, oxidative stress, and inflammation in HepG2 cells treated with palmitic and oleic acids, potentially offering therapeutic benefits for NAFLD providing a possible biochemical mechanism underlying ALA beneficial effects.

Function and regulation of ubiquitin-like SUMO system in heart

The small ubiquitin-related modifier (SUMOylation) system is a conserved, reversible, post-translational protein modification pathway covalently attached to the lysine residues of proteins in eukaryotic cells, and SUMOylation is catalyzed by SUMO-specific activating enzyme (E1), binding enzyme (E2) and ligase (E3). Sentrin-specific proteases (SENPs) can cleave the isopeptide bond of a SUMO conjugate and catalyze the deSUMOylation reaction. SUMOylation can regulate the activity of proteins in many important cellular processes, including transcriptional regulation, cell cycle progression, signal transduction, DNA damage repair and protein stability. Biological experiments in vivo and in vitro have confirmed the key role of the SUMO conjugation/deconjugation system in energy metabolism, Ca2+ cycle homeostasis and protein quality control in cardiomyocytes. In this review, we summarized the research progress of the SUMO conjugation/deconjugation system and SUMOylation-mediated cardiac actions based on related studies published in recent years, and highlighted the further research areas to clarify the role of the SUMO system in the heart by using emerging technologies.

miR-214 could promote myocardial fibrosis and cardiac mesenchymal transition in VMC mice through regulation of the p53 or PTEN-PI3K-Akt signali pathway, promoting CF proliferation and inhibiting its ng pathway

INTRODUCTION

This study aimed to investigate the role of miR-214 in the bidirectional regulation of p53 and PTEN and its influence on myocardial fibrosis and cardiac mesenchymal transformation in mice with viral myocarditis (VMC).

METHODS

The study established a VMC model in BALB/c mice by injecting them with the CVB3 virus intraperitoneally. Techniques such as ELISA, H&E staining, Masson staining, immunohistochemical staining, RT-qPCR, western blot, and dual-luciferase reporter gene assay were used to detect the expression levels of relevant factors in tissues and cells. Isolation and culture of cardiac fibroblasts (CFs) were also conducted.

RESULTS

The study found that miR-214 bidirectional regulation of p53 and PTEN promotes myocardial fibrosis and cardiac mesenchymal transformation in mice with VMC. The expression levels of collagen-related peptides, inflammatory-related factors, miR-214, mesenchymal transformation-related factors, and fibrosis-related factors were significantly increased, while the expression levels of p53, PTEN, and epithelial/endothelial cell phenotype marker factors were significantly decreased. Downregulation of miR-214 or upregulation of p53 and PTEN expression inhibited inflammatory cell and fibroblast infiltration in VMC mouse myocardial tissue. It reduced the proliferation ability while increasing the apoptosis of cardiac fibroblasts.

CONCLUSION

miR-214 plays a significant role in the bidirectional inhibition of p53 and PTEN, which leads to myocardial fibrosis and cardiac mesenchymal transformation in mice with VMC. Downregulation of miR-214 or upregulation of p53 and PTEN expression may provide potential therapeutic targets for treating VMC-induced cardiac fibrosis and mesenchymal transformation.

Mitochondrial dysfunction at the crossroad of cardiovascular diseases and cancer

A large body of evidence indicates the existence of a complex pathophysiological relationship between cardiovascular diseases and cancer. Mitochondria are crucial organelles whose optimal activity is determined by quality control systems, which regulate critical cellular events, ranging from intermediary metabolism and calcium signaling to mitochondrial dynamics, cell death and mitophagy. Emerging data indicate that impaired mitochondrial quality control drives myocardial dysfunction occurring in several heart diseases, including cardiac hypertrophy, myocardial infarction, ischaemia/reperfusion damage and metabolic cardiomyopathies. On the other hand, diverse human cancers also dysregulate mitochondrial quality control to promote their initiation and progression, suggesting that modulating mitochondrial homeostasis may represent a promising therapeutic strategy both in cardiology and oncology. In this review, first we briefly introduce the physiological mechanisms underlying the mitochondrial quality control system, and then summarize the current understanding about the impact of dysregulated mitochondrial functions in cardiovascular diseases and cancer. We also discuss key mitochondrial mechanisms underlying the increased risk of cardiovascular complications secondary to the main current anticancer strategies, highlighting the potential of strategies aimed at alleviating mitochondrial impairment-related cardiac dysfunction and tumorigenesis. It is hoped that this summary can provide novel insights into precision medicine approaches to reduce cardiovascular and cancer morbidities and mortalities.

MicroRNAs as a Potential Biomarker in the Diagnosis of Cardiovascular Diseases

Cardiovascular diseases (CVD) are the leading cause of death in most developed countries. MicroRNAs (miRNAs) are highly investigated molecules not only in CVD but also in other diseases. Several studies on miRNAs continue to reveal novel miRNAs that may play a role in CVD, in their pathogenesis in diagnosis or prognosis, but evidence for clinical implementation is still lacking. The aim of this study is to clarify the diagnostic potential of miRNAs in some CVDs.

Poly (ADP-ribose) polymerases 16 triggers pathological cardiac hypertrophy via activating IRE1α-sXBP1-GATA4 pathway

BACKGROUND

Pressure overload-induced pathological cardiac hypertrophy is an independent predecessor of heart failure (HF), which remains the leading cause of worldwide mortality. However, current evidence on the molecular determinants of pathological cardiac hypertrophy is still inadequacy. This study aims to elucidate the role and mechanisms of Poly (ADP-ribose) polymerases 16 (PARP16) in the pathogenesis of pathological cardiac hypertrophy.

METHODS

Gain and loss of function approaches were used to demonstrate the effects of genetic overexpression or deletion of PARP16 on cardiomyocyte hypertrophic growth in vitro. Ablation of PARP16 by transducing the myocardium with serotype 9 adeno-associated virus (AAV9)-encoding PARP16 shRNA were then subjected to transverse aortic construction (TAC) to investigate the effect of PARP16 on pathological cardiac hypertrophy in vivo. Co-immunoprecipitation (IP) and western blot assay were used to detect the mechanisms of PARP16 in regulating cardiac hypertrophic development.

RESULTS

PARP16 deficiency rescued cardiac dysfunction and ameliorated TAC-induced cardiac hypertrophy and fibrosis in vivo, as well as phenylephrine (PE)-induced cardiomyocyte hypertrophic responses in vitro. Whereas overexpression of PARP16 exacerbated hypertrophic responses including the augmented cardiomyocyte surface area and upregulation of the fetal gene expressions. Mechanistically, PARP16 interacted with IRE1α and ADP-ribosylated IRE1α and then mediated the hypertrophic responses through activating the IRE1α-sXBP1-GATA4 pathway.

CONCLUSIONS

Collectively, our results implicated that PARP16 is a contributor to pathological cardiac hypertrophy at least in part via activating the IRE1α-sXBP1-GATA4 pathway, and may be regarded as a new potential target for exploring effective therapeutic interventions of pathological cardiac hypertrophy and heart failure.

Identification of biomarkers, pathways, and potential therapeutic targets for heart failure using next-generation sequencing data and bioinformatics analysis

BACKGROUND

Heart failure (HF) is the most common cardiovascular diseases and the leading cause of cardiovascular diseases related deaths. Increasing molecular targets have been discovered for HF prognosis and therapy. However, there is still an urgent need to identify novel biomarkers. Therefore, we evaluated biomarkers that might aid the diagnosis and treatment of HF.

METHODS

We searched next-generation sequencing (NGS) dataset (GSE161472) and identified differentially expressed genes (DEGs) by comparing 47 HF samples and 37 normal control samples using limma in R package. Gene ontology (GO) and pathway enrichment analyses of the DEGs were performed using the g: Profiler database. The protein-protein interaction (PPI) network was plotted with Human Integrated Protein-Protein Interaction rEference (HiPPIE) and visualized using Cytoscape. Module analysis of the PPI network was done using PEWCC1. Then, miRNA-hub gene regulatory network and TF-hub gene regulatory network were constructed by Cytoscape software. Finally, we performed receiver operating characteristic (ROC) curve analysis to predict the diagnostic effectiveness of the hub genes.

RESULTS

A total of 930 DEGs, 464 upregulated genes and 466 downregulated genes, were identified in HF. GO and REACTOME pathway enrichment results showed that DEGs mainly enriched in localization, small molecule metabolic process, SARS-CoV infections, and the citric acid tricarboxylic acid (TCA) cycle and respiratory electron transport. After combining the results of the PPI network miRNA-hub gene regulatory network and TF-hub gene regulatory network, 10 hub genes were selected, including heat shock protein 90 alpha family class A member 1 (HSP90AA1), arrestin beta 2 (ARRB2), myosin heavy chain 9 (MYH9), heat shock protein 90 alpha family class B member 1 (HSP90AB1), filamin A (FLNA), epidermal growth factor receptor (EGFR), phosphoinositide-3-kinase regulatory subunit 1 (PIK3R1), cullin 4A (CUL4A), YEATS domain containing 4 (YEATS4), and lysine acetyltransferase 2B (KAT2B).

CONCLUSIONS

This discovery-driven study might be useful to provide a novel insight into the diagnosis and treatment of HF. However, more experiments are needed in the future to investigate the functional roles of these genes in HF.

Molecular Mechanism Underlying Role of the XBP1s in Cardiovascular Diseases

Spliced X-box binding protein-1 (XBP1s) is a protein that belongs to the cAMP-response element-binding (CREB)/activating transcription factor (ATF) b-ZIP family with a basic-region leucine zipper (bZIP). There is mounting evidence to suggest that XBP1s performs a critical function in a range of different cardiovascular diseases (CVDs), indicating that it is necessary to gain a comprehensive knowledge of the processes involved in XBP1s in various disorders to make progress in research and clinical therapy. In this research, we provide a summary of the functions that XBP1s performs in the onset and advancement of CVDs such as atherosclerosis, hypertension, cardiac hypertrophy, and heart failure. Furthermore, we discuss XBP1s as a novel therapeutic target for CVDs.

The Role of the Hypoxia-Related Unfolded Protein Response (UPR) in the Tumor Microenvironment

Despite our understanding of the unfolded protein response (UPR) pathways, the crosstalk between the UPR and the complex signaling networks that different cancers utilize for cell survival remains to be, in most cases, a difficult research barrier. A major problem is the constant variability of different cancer types and the different stages of cancer as well as the complexity of the tumor microenvironments (TME). This complexity often leads to apparently contradictory results. Furthermore, the majority of the studies that have been conducted have utilized two-dimensional in vitro cultures of cancer cells that were exposed to continuous hypoxia, and this approach may not mimic the dynamic and cyclic conditions that are found in solid tumors. Here, we discuss the role of intermittent hypoxia, one of inducers of the UPR in the cellular component of TME, and the way in which intermittent hypoxia induces high levels of reactive oxygen species, the activation of the UPR, and the way in which cancer cells modulate the UPR to aid in their survival. Although the past decade has resulted in defining the complex, novel non-coding RNA-based regulatory networks that modulate the means by which hypoxia influences the UPR, we are now just to beginning to understand some of the connections between hypoxia, the UPR, and the TME.

The down-regulation of XBP1, an unfolded protein response effector, promotes acute kidney injury to chronic kidney disease transition

Background

The activation of the unfolded protein response (UPR) is closely linked to the pathogenesis of renal injuries. However, the role of XBP1, a crucial regulator of adaptive UPR, remains unclear during the transition from acute kidney injury (AKI) to chronic kidney disease (CKD).

Methods

We characterized XBP1 expressions in different mouse models of kidney injuries, including unilateral ischemia–reperfusion injury (UIRI), unilateral ureteral obstruction, and adenine-induced CKD, followed by generating proximal tubular XBP1 conditional knockout (XBP1^cKO) mice for examining the influences of XBP1. Human proximal tubular epithelial cells (HK-2) were silenced of XBP1 to conduct proteomic analysis and investigate the underlying mechanism.

Results

We showed a tripartite activation of UPR in injured kidneys. XBP1 expressions were attenuated after AKI and inversely correlated with the severity of post-AKI renal fibrosis. XBP1^cKO mice exhibited more severe renal fibrosis in the UIRI model than wide-type littermates. Silencing XBP1 induced HK-2 cell cycle arrest in G2M phase, inhibited cell proliferation, and promoted TGF-β1 secretion. Proteomic analysis identified TNF receptor associated protein 1 (Trap1) as the potential downstream target transcriptionally regulated by XBP1s. Trap1 overexpression can alleviate silencing XBP1 induced profibrotic factor expressions and cell cycle arrest.

Conclusion

The loss of XBP1 in kidney injury was profibrotic, and the process was mediated by autocrine and paracrine regulations in combination. The present study identified the XBP1-Trap1 axis as an instrumental mechanism responsible for post-AKI fibrosis, which is a novel regulatory pathway.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12929-022-00828-9.

FTZ protects against cardiac hypertrophy and oxidative injury via microRNA-214 / SIRT3 signaling pathway

BACKGROUND

Despite the fact that the initial hypertrophic response to ventricular pressure overload is thought to be compensatory, prolonged stress often leads to heart failure. Previous studies have shown that the Fufang-Zhenzhu-Tiaozhi (FTZ) formula is beneficial for the treatment of dyslipidemia and hyperglycemia. However, the effects of FTZ on cardiac hypertrophy remain unclear.

OBJECTIVE

The aim of this study is to evaluate the protective effects of FTZ on cardiac hypertrophy and determine the underlying mechanisms.

METHODS

TAC was utilized to establish a cardiac hypertrophy animal model, and FTZ was given via gavage for four weeks. Next, echocardiographic measurements were made. The morphology of mouse cardiomyocytes was examined using H&E and WGA staining. In vitro, the neonatal cardiomyocytes were stimulated with angiotensin Ⅱ (Ang Ⅱ). In addition to measuring the size of cardiomyocytes, qRT-PCR and western blotting were conducted to measure cardiac stress markers and pathway.

RESULTS

According to our findings, FTZ alleviated cardiac hypertrophy in mice and cell models. Furthermore, expression of miR-214 was down-regulated following FTZ, whereas the effect of FTZ therapy was reversed using miR-214 transfection. Furthermore, the expression of Sirtuin 3 (SIRT3) was decreased in Ang Ⅱ-induced oxidative damage, which was associated with a reduction in SOD-1, GPX1, and HO-1 and an increase in MDA, while SIRT3 expression was restored following FTZ treatment.

CONCLUSIONS

Collectively, these findings indicate that FTZ is a protective factor for cardiac hypertrophy due to its regulation of the miR-214-SIRT3 axis, which suggests that FTZ may be a therapeutic target for cardiac hypertrophy.

Endoplasmic Reticulum Stress and miRNA Impairment in Aging and Age-Related Diseases

Aging is a physiological process defined by decreased cellular and tissue functions. Reduced capacity of protein degradation is one of the important hallmarks of aging that may lead to misfolded protein accumulation and progressive loss of function in organ systems. Recognition of unfolded/misfolded protein aggregates via endoplasmic reticulum (ER) stress sensors activates an adaptive mechanism, the unfolded protein response (UPR). The initial step of UPR is defined by chaperone enhancement, ribosomal translation suppression, and misfolded protein degradation, while prolonged ER stress triggers apoptosis. MicroRNAs (miRNAs) are non-coding RNAs affecting various signaling pathways through degradation or translational inhibition of targeted mRNAs. Therefore, UPR and miRNA impairment in aging and age-related diseases is implicated in various studies. This review will highlight the recent insights in ER stress–miRNAs alterations during aging and age-related diseases, including metabolic, cardiovascular, and neurodegenerative diseases and several cancers.

Loxl2 is a mediator of cardiac aging in Drosophila melanogaster; genetically examining the role of aging clock genes

Transcriptomic, proteomic, and methylation aging clocks demonstrate that aging has a predictable preset program, while Transcriptome Trajectory Turning Points indicate that the 20 to 40 age range in humans is the likely stage at which the progressive loss of homeostatic control, and in turn aging, begins to have detrimental effects. Turning points in this age range overlapping with human aging clock genes revealed five candidates that we hypothesized could play a role in aging or age-related physiological decline. To examine these gene's effects on lifespan and health-span, we utilized whole body and heart specific gene knockdown of human orthologs in Drosophila melanogaster. Whole body Loxl2, fz3, and Glo1 RNAi positively affected lifespan as did heart-specific Loxl2 knockdown. Loxl2 inhibition concurrently reduced age-related cardiac arrythmia and collagen (Pericardin) fiber width. Loxl2 binds several transcription factors in humans and RT-qPCR confirmed that a conserved transcriptional target CDH1 (Drosophila CadN2), has expression levels which correlate with Loxl2 reduction in Drosophila. These results point to conserved pathways and multiple mechanisms by which inhibition of Loxl2 can be beneficial to heart health and organismal aging.

An Overview of miRNAs Involved in PASMC Phenotypic Switching in Pulmonary Hypertension

Pulmonary hypertension (PH) is occult, with no distinctive clinical manifestations and a poor prognosis. Pulmonary vascular remodelling is an important pathological feature in which pulmonary artery smooth muscle cells (PASMCs) phenotypic switching plays a crucial role. MicroRNAs (miRNAs) are a class of evolutionarily highly conserved single-stranded small noncoding RNAs. An increasing number of studies have shown that miRNAs play an important role in the occurrence and development of PH by regulating PASMCs phenotypic switching, which is expected to be a potential target for the prevention and treatment of PH. miRNAs such as miR-221, miR-15b, miR-96, miR-24, miR-23a, miR-9, miR-214, and miR-20a can promote PASMCs phenotypic switching, while such as miR-21, miR-132, miR-449, miR-206, miR-124, miR-30c, miR-140, and the miR-17~92 cluster can inhibit it. The article reviews the research progress on growth factor-related miRNAs and hypoxia-related miRNAs that mediate PASMCs phenotypic switching in PH.

Mesenchymal Stem Cell-Derived Extracellular Vesicles Protect Human Corneal Endothelial Cells from Endoplasmic Reticulum Stress-Mediated Apoptosis

Corneal endothelial dystrophy is a relevant cause of vision loss and corneal transplantation worldwide. In the present study, we analyzed the effect of mesenchymal stem cell (MSC)-derived extracellular vesicles (MSC-EVs) in an in vitro model of corneal dystrophy, characterized by endoplasmic reticulum stress. The effects of MSC-EVs were compared with those of serum-derived EVs, reported to display a pro-angiogenic activity. MSC-EVs were able to induce a significant down-regulation of the large majority of endoplasmic reticulum stress-related genes in human corneal endothelial cells after exposure to serum deprivation and tunicamycin. In parallel, they upregulated the Akt pathway and limited caspase-3 activation and apoptosis. At variance, the effect of the serum EVs was mainly limited to Akt phosphorylation, with minimal or absent effects on endoplasmic reticulum stress modulation and apoptosis prevention. The effects of MSC-EVs were correlated to the transfer of numerous endoplasmic reticulum (ER)-stress targeting miRNAs to corneal endothelial cells. These data suggest a potential therapeutic effect of MSC-EVs for corneal endothelial endoplasmic reticulum stress, a major player in corneal endothelial dystrophy.

The long and winding road to target protein misfolding in cardiovascular diseases

BACKGROUND

In the last decades, cardiovascular diseases (CVD) have remained the first leading cause of mortality and morbidity in the world. Although several therapeutic approaches have been introduced in the past, the development of novel treatments remains an important research goal, which is hampered by the lack of understanding of key mechanisms and targets. Emerging evidences in recent years indicate the involvement of misfolded proteins aggregation and the derailment of protein quality control in the pathogenesis of cardiovascular diseases. Several potential interventions targeting protein quality control have been translated from the bench to the bedside to effectively employ the misfolded proteins as promising therapeutic targets for cardiac diseases, but with trivial results.

DESIGN

In this review, we describe the recent progresses in preclinical and clinical studies of protein misfolding and compromised protein quality control by selecting and reporting studies focusing on cardiovascular diseases including cardiomyopathies, cardiac amyloidosis, atherosclerosis, atrial fibrillation and thrombosis.

RESULTS

In preclinical models, modulators of several molecular targets (eg heat shock proteins, unfolded protein response, ubiquitin protein system, autophagy and histone deacetylases) have been tested in various conditions with promising results although lacking an adequate transition towards clinical setting.

CONCLUSIONS

At present, no therapeutic strategies have been reported to attenuate proteotoxicity in patients with CVD due to a lack of specific biomarkers for pinpointing upstream events in protein folding defects at a subclinical stage of the diseases requiring an intensive collaboration between basic scientists and clinicians.

miR-30b-5p Downregulation as a Predictive Biomarker of Coronary In-Stent Restenosis

In-stent restenosis (ISR) is one of the main limitations of percutaneous coronary intervention (PCI) therapy with drug-eluting stents (DES) implantation. The aim of this study was to determine if circulating microRNAs (miRNAs) have diagnostic capability for determining ISR in a cohort of matched patients. Blood samples were collected from 55 patients who underwent previously PCI and were readmitted for a new coronary angiography. Patients were divided into subgroups comprising patients who presented ISR or not (non-ISR). A microarray analysis determined that up to 49 miRNAs were differentially expressed between ISR and non-ISR patients. Of these, 10 miRNAs are related to vascular smooth muscle and endothelial cells proliferation, migration, and differentiation, well-known hallmarks of vascular remodeling. Additionally, we identified that the expression of miR-30b-5p is significantly lower in serum samples of ISR patients, as compared to non-ISR. A further analysis demonstrated that miR-30b-5p provides better values of the receiver operator characteristic curve than other miRNAs and biochemical parameters. Finally, the in-silico analysis suggests that miR-30b-5p is predicted to target 62 genes involved in different signaling pathways involved in vascular remodeling. In conclusion, we determined for the first time that circulating mi-R30b-5p can reliably prognose restenosis in patient with implanted DES, which could be potentially helpful in the establishment of an early diagnosis and therapy of ISR.

Endoplasmic reticulum stress and unfolded protein response in cardiovascular diseases

Cardiovascular diseases (CVDs), such as ischaemic heart disease, cardiomyopathy, atherosclerosis, hypertension, stroke and heart failure, are among the leading causes of morbidity and mortality worldwide. Although specific CVDs and the associated cardiometabolic abnormalities have distinct pathophysiological and clinical manifestations, they often share common traits, including disruption of proteostasis resulting in accumulation of unfolded or misfolded proteins in the endoplasmic reticulum (ER). ER proteostasis is governed by the unfolded protein response (UPR), a signalling pathway that adjusts the protein-folding capacity of the cell to sustain the cell's secretory function. When the adaptive UPR fails to preserve ER homeostasis, a maladaptive or terminal UPR is engaged, leading to the disruption of ER integrity and to apoptosis. ER stress functions as a double-edged sword, with long-term ER stress resulting in cellular defects causing disturbed cardiovascular function. In this Review, we discuss the distinct roles of the UPR and ER stress response as both causes and consequences of CVD. We also summarize the latest advances in our understanding of the importance of the UPR and ER stress in the pathogenesis of CVD and discuss potential therapeutic strategies aimed at restoring ER proteostasis in CVDs.

Biomarkers to predict the response to cardiac resynchronization therapy

Cardiac resynchronization therapy (CRT) is an established non-pharmacological treatment for selected heart failure patients with wide QRS duration. However, there is a persistent number of non-responders throughout. The prediction of the CRT response is paramount to adequately select the correct patients for CRT. One of the expanding fields of research is the development of biomarkers that predict the response to CRT. A review of the available literature on biomarkers in CRT patients has been performed to formulate a critical appraisal of the available data. The main conclusion of our review is that biomarker research in this patient population is very fragmented and broad. This results in the use of non-uniform endpoints to define the CRT response, which precludes an in-depth comparison of the available data. To improve research development in this field, a uniform definition of the CRT response and relevant endpoints is necessary to better predict the CRT response.

Bone marrow mesenchymal stem cells induce M2 microglia polarization through PDGF-AA/MANF signaling

BACKGROUND

Bone marrow mesenchymal stem cells (BMSCs) are capable of shifting the microglia/macrophages phenotype from M1 to M2, contributing to BMSCs-induced brain repair. However, the regulatory mechanism of BMSCs on microglia/macrophages after ischemic stroke is unclear. Recent evidence suggests that mesencephalic astrocyte–derived neurotrophic factor (MANF) and platelet-derived growth factor-AA (PDGF-AA)/MANF signaling regulate M1/M2 macrophage polarization.

AIM

To investigate whether and how MANF or PDGF-AA/MANF signaling influences BMSCs-mediated M2 polarization.

METHODS

We identified the secretion of MANF by BMSCs and developed transgenic BMSCs using a targeting small interfering RNA for knockdown of MANF expression. Using a rat middle cerebral artery occlusion (MCAO) model transplanted by BMSCs and BMSCs–microglia Transwell coculture system, the effect of BMSCs-induced downregulation of MANF expression on the phenotype of microglia/macrophages was tested by Western blot, quantitative reverse transcription-polymerase chain reaction, and immunofluorescence. Additionally, microglia were transfected with mimics of miR-30a*, which influenced expression of X-box binding protein (XBP) 1, a key transcription factor that synergized with activating transcription factor 6 (ATF6) to govern MANF expression. We examined the levels of miR-30a*, ATF6, XBP1, and MANF after PDGF-AA treatment in the activated microglia.

RESULTS

Inhibition of MANF attenuated BMSCs-induced functional recovery and decreased M2 marker production, but increased M1 marker expression in vivo or in vitro. Furthermore, PDGF-AA treatment decreased miR-30a* expression, had no influence on the levels of ATF6, but enhanced expression of both XBP1 and MANF.

CONCLUSION

BMSCs-mediated MANF paracrine signaling, in particular the PDGF-AA/miR-30a*/XBP1/MANF pathway, synergistically mediates BMSCs-induced M2 polarization.

Unfolded protein response in cardiovascular disease

The unfolded protein response (UPR) is a highly conserved molecular machinery, which protects the cells against a diverse variety of stimuli. Activation of this element has been associated with both human health and disease. The purpose of the current manuscript is to provide the most updated information on the involvement of UPR towards the improvement; or deterioration of cardiovascular functions. Since UPR is consisted of three distinct elements, namely the activating transcription factor 6, the protein kinase RNA-like endoplasmic reticulum kinase; and the inositol-requiring enzyme-1α, a highly orchestrated manipulation of those molecular branches may provide new therapeutic possibilities against the severe outcomes of cardiovascular disease.

Role of MicroRNAs in Diagnosis, Prognosis, and Treatment of Acute Heart Failure: Ambassadors from Intracellular Zone

Acute heart failure (AHF) is one of the burdensome diseases affecting a considerable proportion of the population. Recently, it has been demonstrated that micro-ribonucleic acids (miRNAs) can exert diagnostic, prognostic, and therapeutic roles in a variety of conditions including AHF. These molecules play essential roles in HF-related pathophysiology, particularly, cardiac fibrosis, and hypertrophy. Some miRNAs namely miRNA-423-5p are reported to have both diagnostic and prognostic capabilities. However, some studies suggest that combination of biomarkers is a much better way to achieve the highest accuracy such as the combination of miRNAs and N-terminal pro b-type Natriuretic Peptide (NT pro-BNP). Therefore, this review discusses different views towards various roles of miRNAs in AHF.

A tangled tale of microRNA and cardiac fibrosis

Cardiac fibrosis is important for wound healing, regeneration and producing the extracellular matrix (ECM) that provides the scaffold for cells. In pathological situations, fibroblasts are activated and remodel the ECM. In volume 133, issue 17 of Clinical Science, Yang et al. discovered that the miR-214-3p/NLRC5 axis is important for fibroblast-to-myofibroblast transition (FMT) and ECM remodelling in a pressure overload model of fibrosis [Clin. Sci. (2019) 133(17), 1845-1856]. This discovery helps to explain the complicated regulation of cardiac fibrosis. It also underscores the need for more investigation into the mechanisms of cardiac fibrosis to develop better diagnostic modalities and therapeutic options in heart failure.

ETS2 and microRNA-155 regulate the pathogenesis of heart failure through targeting and regulating GPR18 expression

Heart failure (HF) is a global pandemic cardiovascular disease with increasing prevalence, but the pathogenesis remains to be elucidated. The present study aimed to investigate the underlying mechanism in heart failure (HF) using bioinformatics and experimental validation. A HF-associated dataset GSE84796 was downloaded from the Gene Expression Omnibus database and differentially expressed genes (DEGs) were screened for using Bayes method in the Limma package. Kyoto Encyclopedia of Genes and Genomes pathway analysis was used to perform pathway enrichment analysis of these DEGs using The Database for Annotation, Visualization and Integrated Discovery. A protein-protein interaction (PPI) network of DEG-encoded proteins was subsequently constructed using the Search tool for the Retrieval of Interacting Genes/Proteins, and a transcription factor (TF)/miRNA-target network was constructed according to the WEB-based Gene SeT AnaLysis Tookit. The expression levels of microRNA (miRNA/miR)-155, G-protein coupled receptor 18 (GRP18) and E26 transformation-specific transcription factor 2 (ETS2) were analyzed in clinical HF samples, and functional validations were performed in H9c2 (2-1) cells. A total of 419 DEGs were identified, including 366 upregulated genes and 53 downregulated genes. The upregulated DEGs were significantly enriched in the pathways of ‘cytokine-cytokine receptor interaction’, ‘natural killer cell mediated cytotoxicity’ and ‘primary immunodeficiency’. A total of two functional modules were identified in the PPI network: Module A was enriched in 3 KEGG pathways and module B was enriched in 15 KEGG pathways. Furthermore, a total of three miRNAs and eight TFs were identified in the TF/miRNA-target network. Specifically, GPR18 was discovered to be targeted by both ETS2 and miR-155. Clinical validation revealed that the expression levels of miR-155 were significantly decreased in the HF samples, whereas the expression levels of ETS2 and GPR18 were significantly increased in HF samples. In conclusion, the present study suggested that GPR18 may be a target of ETS2 and miR-155, and miR-155 may regulate cell viability and apoptosis in H9c2 (2-1) cells through targeting and regulating GPR18.

Unfolded protein response (UPR) integrated signaling networks determine cell fate during hypoxia

During hypoxic conditions, cells undergo critical adaptive responses that include the up-regulation of hypoxia-inducible proteins (HIFs) and the induction of the unfolded protein response (UPR). While their induced signaling pathways have many distinct targets, there are some important connections as well. Despite the extensive studies on both of these signaling pathways, the exact mechanisms involved that determine survival versus apoptosis remain largely unexplained and therefore beyond therapeutic control. Here we discuss the complex relationship between the HIF and UPR signaling pathways and the importance of understanding how these pathways differ between normal and cancer cell models.

microRNAs in Cardiovascular Disease: Small Molecules but Big Roles

microRNAs (miRNAs) are an evolutionarily conserved class of small single-stranded noncoding RNAs. The aberrant expression of specific miRNAs has been implicated in the development and progression of diverse cardiovascular diseases. For many decades, miRNA therapeutics has flourished, taking advantage of the fact that miRNAs can modulate gene expression and control cellular phenotypes at the posttranscriptional level. Genetic replacement or knockdown of target miRNAs by chemical molecules, referred to as miRNA mimics or inhibitors, has been used to reverse their abnormal expression as well as their adverse biological effects in vitro and in vivo in an effort to fully implement the therapeutic potential of miRNA-targeting treatment. However, the limitations of the chemical structure and delivery systems are hindering progress towards clinical translation. Here, we focus on the regulatory mechanisms and therapeutic trials of several representative miRNAs in the context of specific cardiovascular diseases; from this basic perspective, we evaluate chemical modifications and delivery vectors of miRNA-based chemical molecules and consider the underlying challenges of miRNA therapeutics as well as the clinical perspectives on their applications.

The microRNA in ventricular remodeling: the miR-30 family

Ventricular remodeling (VR) is a complex pathological process of cardiomyocyte apoptosis, cardiac hypertrophy, and myocardial fibrosis, which is often caused by various cardiovascular diseases (CVDs) such as hypertension, acute myocardial infarction, heart failure (HF), etc. It is also an independent risk factor for a variety of CVDs, which will eventually to damage the heart function, promote cardiovascular events, and lead to an increase in mortality. MicroRNAs (miRNAs) can participate in a variety of CVDs through post-transcriptional regulation of target gene proteins. Among them, microRNA-30 (miR-30) is one of the most abundant miRNAs in the heart. In recent years, the study found that the miR-30 family can participate in VR through a variety of mechanisms, including autophagy, apoptosis, oxidative stress, and inflammation. VR is commonly found in ischemic heart disease (IHD), hypertensive heart disease (HHD), diabetic cardiomyopathy (DCM), antineoplastic drug cardiotoxicity (CTX), and other CVDs. Therefore, we will review the relevant mechanisms of the miR-30 in VR induced by various diseases.

miR-34c-5p modulates X-box-binding protein 1 (XBP1) expression during the adaptive phase of the unfolded protein response

During endoplasmic reticulum (ER) stress conditions, an adaptive signaling network termed the unfolded protein response (UPR) is activated. The UPR's function is to increase ER protein-folding capacity in order to attenuate ER stress, restore ER homeostasis, and, most importantly, promote cell survival. X-box-binding protein 1 (XBP1) is one component of the UPR and is a proadaptive transcription factor that is subject to transcriptional, post-transcriptional, and post-translational control. In the present study, we identified a post-transcriptional mechanism mediated by miR-34c-5p that governs the expression of both the spliced (active) and unspliced (latent) forms of XBP1 mRNAs. We showed that miR-34c-5p directly attenuates spliced XBP1 (XBP1s) mRNA levels during ER stress and thus regulates the proadaptive component of the UPR that is mediated by XBP1s without interfering with the induction of apoptotic responses.-Bartoszewska, S., Cabaj, A., Dąbrowski, M., Collawn, J. F., Bartoszewski, R. miR-34c-5p modulates X-box-binding protein 1 (XBP1) expression during the adaptive phase of the unfolded protein response.

Endoplasmic reticulum and the microRNA environment in the cardiovascular system 1

Stress responses are important to human physiology and pathology, and the inability to adapt to cellular stress leads to cell death. To mitigate cellular stress and re-establish homeostasis, cells, including those in the cardiovascular system, activate stress coping response mechanisms. The endoplasmic reticulum, a component of the cellular reticular network in cardiac cells, mobilizes so-called endoplasmic reticulum stress coping responses, such as the unfolded protein response. MicroRNAs play an important part in the maintenance of cellular and tissue homeostasis, perform a central role in the biology of the cardiac myocyte, and are involved in pathological cardiac function and remodeling. In this paper, we review a link between endoplasmic reticulum homeostasis and microRNA with an emphasis on the impact on stress responses in the cardiovascular system.

Unfolded Protein Response as a Therapeutic Target in Cardiovascular Disease

Cardiovascular disease is the leading cause of death worldwide. Despite overwhelming socioeconomic impact and mounting clinical needs, our understanding of the underlying pathophysiology remains incomplete. Multiple forms of cardiovascular disease involve an acute or chronic disturbance in cardiac myocytes, which may lead to potent activation of the Unfolded Protein Response (UPR), a cellular adaptive reaction to accommodate protein-folding stress. Accumulation of unfolded or misfolded proteins in the Endoplasmic Reticulum (ER) elicits three signaling branches of the UPR, which otherwise remain quiescent. This ER stress response then transiently suppresses global protein translation, augments production of protein-folding chaperones, and enhances ER-associated protein degradation, with an aim to restore cellular homeostasis. Ample evidence has established that the UPR is strongly induced in heart disease. Recently, the mechanisms of action and multiple pharmacological means to favorably modulate the UPR are emerging to curb the initiation and progression of cardiovascular disease. Here, we review the current understanding of the UPR in cardiovascular disease and discuss existing therapeutic explorations and future directions.

MicroRNA Expression is Associated with Sepsis Disorders in Critically Ill Polytrauma Patients

A critically ill polytrauma patient is one of the most complex cases to be admitted to the intensive care unit, due to both the primary traumatic complications and the secondary post-traumatic interactions. From a molecular, genetic, and epigenetic point of view, numerous biochemical interactions are responsible for the deterioration of the clinical status of a patient, and increased mortality rates. From a molecular viewpoint, microRNAs are one of the most complex macromolecular systems due to the numerous modular reactions and interactions that they are involved in. Regarding the expression and activity of microRNAs in sepsis, their usefulness has reached new levels of significance. MicroRNAs can be used both as an early biomarker for sepsis, and as a therapeutic target because of their ability to block the complex reactions involved in the initiation, maintenance, and augmentation of the clinical status.

Noncoding RNAs in Cardiac Hypertrophy

Cardiac hypertrophy is classified as pathological and physiological hypertrophy. Pathological hypertrophy typically precedes the onset of heart failure, one of the largest contributors to disease burden and deaths worldwide. In contrast, physiological hypertrophy is an adaptive response and protects against adverse cardiac remodeling. Noncoding RNAs (ncRNAs) have drawn significant attention over the last couple of decades, and their dysregulation is increasingly being linked to cardiac hypertrophy and cardiovascular diseases. In this review, we will summarize the profiling, function, and molecular mechanism of microRNAs, long noncoding RNAs, and circular RNAs in pathological cardiac hypertrophy. Additionally, we also review microRNAs responsible for physiological hypertrophy. With better understanding of ncRNAs in cardiac hypertrophy, manipulation of the important ncRNAs will offer exciting avenues for the prevention and therapy of heart failure.

Contrary microRNA Expression Pattern Between Fetal and Adult Cardiac Remodeling: Therapeutic Value for Heart Failure

microRNAs (miRNAs) belong to a class of non-coding RNAs that regulate post-transcriptional gene expression during development and disease. Growing evidence indicates abundant miRNA expression changes and their important role in cardiac hypertrophy and failure. However, the role of miRNAs in fetal cardiac remodeling is little known. Here, we investigated the altered expression of fifteen miRNAs in rat fetal cardiac remodeling compared with adult cardiac remodeling. Among fifteen tested miRNAs, eleven and five miRNAs (miR-199a-5p, miR-214-3p, miR-155-3p, miR-155-5p and miR-499-5p) are significantly differentially expressed in fetal and adult cardiac remodeling, respectively. After comparison of miRNA expression in fetal and adult cardiac remodeling, we find that miRNA expression returns to the fetal level in adult cardiac failure and is activated in advance of the adult level in fetal failure. The current study highlights the contrary expression pattern between fetal and adult cardiac remodeling and that supports a novel potential therapeutic approach to treating heart failure.

Endoplasmic reticulum stress in the heart: insights into mechanisms and drug targets

The endoplasmic reticulum (ER) serves several essential cellular functions including protein synthesis, protein folding, protein translocation, calcium homoeostasis and lipid biosynthesis. Physiological or pathological stimuli, which disrupt ER homoeostasis and disturb its functions, lead to an accumulation of misfolded and unfolded proteins, a condition referred to as ER stress. ER stress triggers the unfolded protein response to restore the homoeostasis of ER, through activating transcriptional and translational pathways. However, prolonged ER stress will lead to cell dysfunction and apoptosis. Recent evidence revealed that ER stress is involved in the development and progression of various heart diseases, such as cardiac hypertrophy, ischaemic heart diseases and heart failure. Therefore, improved understanding of the molecular mechanisms of ER stress in heart disease will help to investigate more potential targets for new therapeutic interventions and drug discovery.

LINKED ARTICLES

This article is part of a themed section on Spotlight on Small Molecules in Cardiovascular Diseases. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.8/issuetoc.

Mechanisms of β-cell dedifferentiation in diabetes: recent findings and future research directions

Like all the cells of an organism, pancreatic β-cells originate from embryonic stem cells through a complex cellular process termed differentiation. Differentiation involves the coordinated and tightly controlled activation/repression of specific effectors and gene clusters in a time-dependent fashion thereby giving rise to particular morphological and functional cellular features. Interestingly, cellular differentiation is not a unidirectional process. Indeed, growing evidence suggests that under certain conditions, mature β-cells can lose, to various degrees, their differentiated phenotype and cellular identity and regress to a less differentiated or a precursor-like state. This concept is termed dedifferentiation and has been proposed, besides cell death, as a contributing factor to the loss of functional β-cell mass in diabetes. β-cell dedifferentiation involves: (1) the downregulation of β-cell-enriched genes, including key transcription factors, insulin, glucose metabolism genes, protein processing and secretory pathway genes; (2) the concomitant upregulation of genes suppressed or expressed at very low levels in normal β-cells, the β-cell forbidden genes; and (3) the likely upregulation of progenitor cell genes. These alterations lead to phenotypic reconfiguration of β-cells and ultimately defective insulin secretion. While the major role of glucotoxicity in β-cell dedifferentiation is well established, the precise mechanisms involved are still under investigation. This review highlights the identified molecular mechanisms implicated in β-cell dedifferentiation including oxidative stress, endoplasmic reticulum (ER) stress, inflammation and hypoxia. It discusses the role of Foxo1, Myc and inhibitor of differentiation proteins and underscores the emerging role of non-coding RNAs. Finally, it proposes a novel hypothesis of β-cell dedifferentiation as a potential adaptive mechanism to escape cell death under stress conditions.

Regulation of the unfolded protein response by noncoding RNA

Cells are exposed to various intrinsic and extrinsic stresses in both physiological and pathological conditions. To adapt to those conditions, cells have evolved various mechanisms to cope with the disturbances in protein demand, largely through the unfolded protein response (UPR) in the endoplasmic reticulum (ER), but also through the integrated stress response (ISR). Both responses initiate downstream signaling to transcription factors that, in turn, trigger adaptive programs and/or in the case of prolonged stress, cell death mechanisms. Recently, noncoding RNAs, including microRNA and long noncoding RNA, have emerged as key players in the stress responses. These noncoding RNAs act as both regulators and effectors of the UPR and fine-tune the output of the stress signaling pathways. Although much is known about the UPR and the cross talk that exists between pathways, the contribution of small noncoding RNA has not been fully assessed. Herein we bring together and review the current known functions of noncoding RNA in regulating adaptive pathways in both physiological and pathophysiological conditions, illustrating how they operate within the known UPR functions and contribute to diverse cellular outcomes.

Mechanisms contributing to cardiac remodelling

Cardiac remodelling is classified as physiological (in response to growth, exercise and pregnancy) or pathological (in response to inflammation, ischaemia, ischaemia/reperfusion (I/R) injury, biomechanical stress, excess neurohormonal activation and excess afterload). Physiological remodelling of the heart is characterized by a fine-tuned and orchestrated process of beneficial adaptations. Pathological cardiac remodelling is the process of structural and functional changes in the left ventricle (LV) in response to internal or external cardiovascular damage or influence by pathogenic risk factors, and is a precursor of clinical heart failure (HF). Pathological remodelling is associated with fibrosis, inflammation and cellular dysfunction (e.g. abnormal cardiomyocyte/non-cardiomyocyte interactions, oxidative stress, endoplasmic reticulum (ER) stress, autophagy alterations, impairment of metabolism and signalling pathways), leading to HF. This review describes the key molecular and cellular responses involved in pathological cardiac remodelling.

The role of miR-214 in cardiovascular diseases

Cardiovascular disease (CVD) is the leading cause of death throughout the world. The increase in new patients every year leads to a demand for the identification of valid and novel prognostic and diagnostic biomarkers for the prevention and treatment of cardiovascular diseases. MicroRNAs (miRNAs) are critical endogenous small noncoding RNAs that negatively modulate gene expression by regulating its translation. miRNAs are implicated in most physiological processes of the heart and in the pathological progression of cardiovascular diseases. miR-214 is a deregulated miRNA in many pathological conditions, and it contributes to the pathogenesis of multiple human disorders, including cancer and cardiovascular diseases. miR-214 has dual functions in different cardiac pathological circumstances. However, it is considered as a promising marker in the prognosis, diagnosis and treatment of cardiovascular diseases. In this review, we discuss the role of miR-214 in various cardiac disease conditions, including ischaemic heart diseases, cardiac hypertrophy, pulmonary arterial hypertension (PAH), angiogenesis following vascular injury and heart failure.

[Use of microRNAs in heart failure management]

Heart failure (HF) is a high impact disease that affects all human populations, demanding the development of new strategies and methods to manage this pathology. That's why microRNAs, small noncoding RNAs that regulate gene expression, appear as an important option in the diagnosis, prognosis and treatment of this disease. MiRNAs seems to have a future on HF handling, because can be isolated from body fluids such as blood, and changes in its levels can be associated with the presence, stage and specific disease features, which makes them an interesting option as biomarkers. Also, due to the important role of these molecules on regulation of gene expression and cell homeostasis, it has been explored its potential use as a therapeutic method to prevent or treat HF. That is why this review seeks to show the importance of biomedical research involving the use of miRNAs as a method to approach the HF, showing the impact of disease in the world, aspects of miRNAs biology, and their use as biomarkers and as important therapeutic targets.

MicroRNA-297 promotes cardiomyocyte hypertrophy via targeting sigma-1 receptor

AIMS

Sigma-1 receptor (Sig-1R) is a ligand-regulated endoplasmic reticulum (ER) chaperone involved in cardiac hypertrophy, but it is not known whether Sig-1R is regulated by microRNAs (miRNAs). According to bioinformatic analysis, miR-297 was suggested as a potential target miRNA for Sig-1R. Therefore, we verified whether miR-297 could target Sig-1R and investigated the possible mechanisms underlying the role of miR-297 in cardiac hypertrophy.

MAIN METHODS

Bioinformatic analysis combined with laboratory experiments, including quantitative RT-PCR, Western blotting, and luciferase assay, were performed to identify the target miRNA of Sig-1R. Transverse aortic constriction (TAC) model and neonatal rat cardiomyocytes (NCMs) stimulated with angiotensin II (AngII) were used to explore the relationship between miR-297 and Sig-1R. Additionally, the function of miR-297 in cardiomyocyte hypertrophy and ER stress/unfolded protein response (UPR) signaling pathway was investigated by transfecting miR-297 mimics/inhibitor.

KEY FINDINGS

miR-297 levels were increased in both TAC-induced hypertrophic heart tissue and AngII-induced cardiomyocyte hypertrophy. Up-regulation of miR-297 by specific mimics exacerbated AngII-induced cardiomyocyte hypertrophy, whereas inhibition of miR-297 suppressed the process. During cardiomyocyte hypertrophy, Sig-1R expression, which was negatively regulated by miR-297 by directly targeting its 3'untranslated region (UTR), was decreased. Furthermore, attenuation of miR-297 inhibited the activation of X-box binding protein 1 (Xbp1) and activating transcriptional factor 4 (ATF4) signaling pathways in NCMs.

SIGNIFICANCE

Our data demonstrate that miR-297 promotes cardiomyocyte hypertrophy by inhibiting the expression of Sig-1R and activation of ER stress signaling, which provides a novel interpretation for cardiac hypertrophy.

Myocyte-specific enhancer factor 2C: a novel target gene of miR-214-3p in suppressing angiotensin II-induced cardiomyocyte hypertrophy

The role of microRNA-214-3p (miR-214-3p) in cardiac hypertrophy was not well illustrated. The present study aimed to investigate the expression and potential target of miR-214-3p in angiotensin II (Ang-II)-induced mouse cardiac hypertrophy. In mice with either Ang-II infusion or transverse aortic constriction (TAC) model, miR-214-3p expression was markedly decreased in the hypertrophic myocardium. Down-regulation of miR-214-3p was observed in the myocardium of patients with cardiac hypertrophy. Expression of miR-214-3p was upregulated in Ang-II-induced hypertrophic neonatal mouse ventricular cardiomyocytes. Cardiac hypertrophy was attenuated in Ang-II-infused mice by tail vein injection of miR-214-3p. Moreover, miR-214-3p inhibited the expression of atrial natriuretic peptide (ANP) and β-myosin heavy chain (MHC) in Ang-II-treated mouse cardiomyocytes in vitro. Myocyte-specific enhancer factor 2C (MEF2C), which was increased in Ang-II-induced hypertrophic mouse myocardium and cardiomyocytes, was identified as a target gene of miR-214-3p. Functionally, miR-214-3p mimic, consistent with MEF2C siRNA, inhibited cell size increase and protein expression of ANP and β-MHC in Ang-II-treated mouse cardiomyocytes. The NF-κB signal pathway was verified to mediate Ang-II-induced miR-214-3p expression in cardiomyocytes. Taken together, our results revealed that MEF2C is a novel target of miR-214-3p, and attenuation of miR-214-3p expression may contribute to MEF2Cexpressionin cardiac hypertrophy.

Deregulation of XBP1 expression contributes to myocardial vascular endothelial growth factor-A expression and angiogenesis during cardiac hypertrophy in vivo

Endoplasmic reticulum (ER) stress has been reported to be involved in many cardiovascular diseases such as atherosclerosis, diabetes, myocardial ischemia, and hypertension that ultimately result in heart failure. XBP1 is a key ER stress signal transducer and an important pro‐survival factor of the unfolded protein response (UPR) in mammalian cells. The aim of this study was to establish a role for XBP1 in the deregulation of pro‐angiogenic factor VEGF expression and potential regulatory mechanisms in hypertrophic and failing heart. Western blots showed that myocardial XBP1s protein was significantly increased in both isoproterenol (ISO)‐induced and pressure‐overload‐induced hypertrophic and failing heart compared to normal control. Furthermore, XBP1 silencing exacerbates ISO‐induced cardiac dysfunction along with a reduction of myocardial capillary density and cardiac expression of pro‐angiogenic factor VEGF‐A in vivo. Consistently, experiments in cultured cardiomyocytes H9c2 (2‐1) cells showed that UPR‐induced VEGF‐A upregulation was determined by XBP1 expression level. Importantly, VEGF‐A expression was increased in failing human heart tissue and blood samples and was correlated with the levels of XBP1. These results suggest that XBP1 regulates VEGF‐mediated cardiac angiogenesis, which contributes to the progression of adaptive hypertrophy, and might provide novel targets for prevention and treatment of heart failure.

Dynamic regulation of uncoupling protein 2 expression by microRNA-214 in hepatocellular carcinoma

Gemcitabine (GEM), a commonly used chemotherapeutic agent in hepatocellular carcinoma (HCC) patients, uses oxidative stress induction as a common effector pathway. However, GEM alone or in combination with oxaliplatin hardly renders any survival benefits to HCC patients. We have recently shown that this is part due to the overexpression of the mitochondrial uncoupling protein 2 (UCP2) that in turn mediates resistance to GEM in HCC patients. However, not much is known about regulatory mechanisms underlying UCP2 overexpression in HCC. Differential protein expression in HCC cell lines did not show a concomitant change in UCP2 transcript level, indicating post-transcriptional or post-translational regulatory mechanism. In situ analysis revealed that UCP2 is a putative target of miR-214 miR-214 expression is significantly down-regulated in HCC patient samples as compared with normal adjacent tissues and in cell line, human hepatoblastoma cells (HuH6), with high UCP2 protein expression. We demonstrated using miR-214 mimic and antagomir that the miRNA targeted UCP2 expression by directly targeting the wild-type, but not a miR-214 seed mutant, 3' UTR of UCP2 Overexpression of miR-214 significantly attenuated cell proliferation. Finally, analysis in 20 HCC patients revealed an inverse correlation in expression of UCP2 and miR-214 (Pearson's correlation coefficient, r=-0.9792). Cumulatively, our data indicate that in the context of HCC, miR-214 acts as a putative tumour suppressor by targeting UCP2 and defines a novel mechanism of regulation of UCP2.

Overview of MicroRNAs in Cardiac Hypertrophy, Fibrosis, and Apoptosis

MicroRNAs (miRNAs) are non-coding RNAs that play essential roles in modulating the gene expression in almost all biological events. In the past decade, the involvement of miRNAs in various cardiovascular disorders has been explored in numerous in vitro and in vivo studies. In this paper, studies focused upon the discovery of miRNAs, their target genes, and functionality are reviewed. The selected miRNAs discussed herein have regulatory effects on target gene expression as demonstrated by miRNA/3′ end untranslated region (3′UTR) interaction assay and/or gain/loss-of-function approaches. The listed miRNA entities are categorized according to the biological relevance of their target genes in relation to three cardiovascular pathologies, namely cardiac hypertrophy, fibrosis, and apoptosis. Furthermore, comparison across 86 studies identified several candidate miRNAs that might be of particular importance in the ontogenesis of cardiovascular diseases as they modulate the expression of clusters of target genes involved in the progression of multiple adverse cardiovascular events. This review illustrates the involvement of miRNAs in diverse biological signaling pathways and provides an overview of current understanding of, and progress of research into, of the roles of miRNAs in cardiovascular health and disease.

MicroRNA and Heart Failure

Heart failure (HF) imposes significant economic and public health burdens upon modern society. It is known that disturbances in neurohormonal status play an important role in the pathogenesis of HF. Therapeutics that antagonize selected neurohormonal pathways, specifically the renin-angiotensin-aldosterone and sympathetic nervous systems, have significantly improved patient outcomes in HF. Nevertheless, mortality remains high with about 50% of HF patients dying within five years of diagnosis thus mandating ongoing efforts to improve HF management. The discovery of short noncoding microRNAs (miRNAs) and our increasing understanding of their functions, has presented potential therapeutic applications in complex diseases, including HF. Results from several genome-wide miRNA studies have identified miRNAs differentially expressed in HF cohorts suggesting their possible involvement in the pathogenesis of HF and their potential as both biomarkers and as therapeutic targets. Unravelling the functional relevance of miRNAs within pathogenic pathways is a major challenge in cardiovascular research. In this article, we provide an overview of the role of miRNAs in the cardiovascular system. We highlight several HF-related miRNAs reported from selected cohorts and review their putative roles in neurohormonal signaling.

Chronic heart failure: Ca(2+), catabolism, and catastrophic cell death

Robust successes have been achieved in recent years in conquering the acutely lethal manifestations of heart disease. Many patients who previously would have died now survive to enjoy happy and productive lives. Nevertheless, the devastating impact of heart disease continues unabated, as the spectrum of disease has evolved with new manifestations. In light of this ever-evolving challenge, insights that culminate in novel therapeutic targets are urgently needed. Here, we review fundamental mechanisms of heart failure, both with reduced (HFrEF) and preserved (HFpEF) ejection fraction. We discuss pathways that regulate cardiomyocyte remodeling and turnover, focusing on Ca(2+) signaling, autophagy, and apoptosis. In particular, we highlight recent insights pointing to novel connections among these events. We also explore mechanisms whereby potential therapeutic approaches targeting these processes may improve morbidity and mortality in the devastating syndrome of heart failure.