Featured Article: microRNA-125a in pulmonary hypertension: Regulator of a proliferative phenotype of endothelial cells

Recent progress in the roles of microRNAs in pulmonary arterial hypertension associated with congenital heart disease

Research on noncoding RNA, particularly microRNAs (miRNAs), is growing rapidly. Advances in genomic technologies have revealed the complex roles of miRNAs in pulmonary arterial hypertension (PAH) associated with congenital heart disease (CHD). It has been demonstrated that the progression of PAH associated with CHD is characterized by particular dysregulation of miRNAs and is related to cardiovascular remodeling, cell death, and right ventricle dysfunction. This review provides a comprehensive overview of the current state of knowledge regarding the involvement of miRNAs in the pathogenesis and progression of PAH associated with CHD. We commence by explaining the process of miRNA synthesis and its mode of action, as well as the role of miRNA in PAH associated with CHD. Moreover, the article delves into current breakthroughs in research, potential clinical implications, and prospects for future investigations. The review provides the insight into novel approaches for diagnosis, prognosis, and therapy of PAH associated with CHD.

MiR-122-5p as a potential regulator of pulmonary vascular wall cell in idiopathic pulmonary arterial hypertension

MicroRNAs (miRNAs) are versatile regulators of pulmonary arterial remodeling in idiopathic pulmonary arterial hypertension (IPAH). We herein aimed to characterize miRNAs in peripheral blood mononuclear cell (PBMC) and plasma exosomes, and investigate specific miRNA expression in pulmonary artery cells and lung tissues in IPAH. A co-dysregulated miRNA was identified from the miRNA expression profiles of PBMC and plasma exosomes in IPAH. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed the potential function of differentially expressed miRNAs. Real-time quantitative reverse transcription polymerase chain reaction was used to validate the expression of specific miRNAs in hypoxia-induced pulmonary microvascular endothelial cells (PMECs), pulmonary artery smooth muscle cells (PASMCs), pericyte cells (PCs), and lung tissues of patients with IPAH and rats. Finally, the miRNA-mRNA mechanisms of miR-122-5p were predicted. MiR-122-5p was the only co-upregulated miRNA in PBMC and plasma exosomes in patients with IPAH. Functional analysis of differentially expressed miRNAs revealed associations with the GO terms "transcription, DNA-templated," "cytoplasm," and "metal ion binding" in both PBMC and plasma exosomes, KEGG pathway MAPK signaling in PBMC, and KEGG-pathway human papillomavirus infection in plasma exosomes. Hypoxic PMECs and PCs, lung tissue of patients with IPAH, and rats showed increased expression of miR-122-5p, but hypoxic PASMCs showed decreased expression. And miR-122-5p mimics and inhibitor affected cell proliferation. Finally, miR-122-5p was found to potentially target DLAT (in lung tissue) and RIMS1 (in PMECs) in IPAH. According to the dual-luciferase assay, miR-122-5p bound to DLAT or RIMS1. In studies, DLAT imbalance was associated with cell proliferation and migration, RIMS1 is differentially expressed in cancer and correlated with cancer prognosis. Our findings suggest that the miR-122-5p is involved in various biological functions in the adjacent vascular wall cells in IPAH.

Critical miRNAs in regulating pulmonary hypertension: A focus on Signaling pathways and therapeutic Targets

Pulmonary hypertension (PH) is complex disease as a result of obstructive pulmonary arterial remodeling, which in turn results in elevated pulmonary arterial pressure (PAP) and subsequent right ventricular heart failure, eventually leading to premature death. However, there is still a lack of a diagnostic blood-based biomarker and therapeutic target for PH. Because of the difficulty of diagnosis, new and more easily accessible prevention and treatment strategy are being explored. New target and diagnosis biomarkers should also allow for early diagnosis. In biology, miRNAs are short endogenous RNA molecules that are not coding. It is known that miRNAs can regulate gene expression and affect a variety of biological processes. Besides, miRNAs have been proven to be a crucial factor in PH pathogenesis. miRNAs have various effects on pulmonary vascular remodeling and are expressed differentially in various pulmonary vascular cells. Nowadays, it has been shown to be critical in the functions of different miRNAs in the pathogenesis of PH. Therefore, clarifying the mechanism of miRNAs regulating pulmonary vascular remodeling is of great importance to explore new therapeutic targets of PH and improve the survival qualify and time of patients. This review is focused on the role, mechanism, and potential therapeutic targets of miRNAs in PH and puts forward possible clinical treatment strategies.

Biomarker-based approach to determine etiology and severity of pulmonary hypertension: Focus on microRNA

Pulmonary arterial hypertension (PAH) is characterized by remodeling of the pulmonary arteries, and defined by elevated pulmonary arterial pressure, measured during right heart catheterization. There are three main challenges to the diagnostic and therapeutic process of patients with PAH. First, it is difficult to differentiate particular PAH etiology. Second, invasive diagnostic is required to precisely determine the severity of PAH, and thus to qualify patients for an appropriate treatment. Third, the results of treatment of PAH are unpredictable and remain unsatisfactory. MicroRNAs (miRNAs) are small non-coding RNAs that regulate post transcriptional gene-expression. Their role as a prognostic, and diagnostic biomarkers in many different diseases have been studied in recent years. MiRNAs are promising novel biomarkers in PAH due to their activity in various molecular pathways and processes underlying PAH. Lack of biomarkers to differentiate between particular PAH etiology and evaluate the severity of PAH, as well as paucity of therapeutic targets in PAH open a new field for the possibility to use miRNAs in these applications. In our article, we discuss the potential of miRNAs use as diagnostic tools, prognostic biomarkers and therapeutic targets in PAH.

The key roles of non-coding RNAs in the pathophysiology of hypertension

Hypertension is a multifactorial condition in which several genetic and environmental elements contribute. Recent investigations have revealed contribution of non-coding region of the transcriptome in this trait. CDKN2B-AS1, AK098656, MEG3, H19, PAXIP1-AS1, TUG1, GAS5, CASC2 and CPS1-IT are among long non-coding RNAs participating in the pathophysiology of hypertension. Several miRNAs have also been found to be implicated in this disorder. miR-296, miR-637, miR-296, miR-637, hsa-miR-361-5p, miR-122-5p, miR-199a-3p, miR-208a-3p, miR-423-5p, miR-223-5p and miR-140-5p are among dysregulated miRNAs in this condition whose application as diagnostic biomarkers for hypertension has been evaluated. Finally, hsa-circ-0005870, hsa_circ_0037911 and hsa_circ_0014243 are examples of dysregulated circular RNAs in hypertensive patients. In the current review, we describe the role of these non-coding RNAs in the pathophysiology of hypertension.

ncRNAs and polyphenols: new therapeutic strategies for hypertension

Polyphenols have gained significant attention in protecting several chronic diseases, such as cardiovascular diseases (CVDs). Accumulating evidence indicates that polyphenols have potential protective roles for various CVDs. Hypertension (HTN) is among the hazardous CVDs accounting for nearly 8.5 million deaths worldwide. HTN is a complex and multifactorial disease and a combination of genetic susceptibility and environmental factors play major roles in its development. However, the underlying regulatory mechanisms are still elusive. Polyphenols have shown to cause favourable and beneficial effects in the management of HTN. Noncoding RNAs (ncRNAs) as influential mediators in modulating the biological properties of polyphenols, have shown significant footprints in CVDs. ncRNAs control basic functions in virtually all cell types relevant to the cardiovascular system and, thus, a direct link with blood pressure (BP) regulation is highly probable. Recent evidence suggests that a number of ncRNAs, including main small ncRNAs, microRNAs (miRNAs) and long ncRNAs (lncRNAs), play crucial roles with respect to the antihypertensive effects of polyphenols. Indeed, targeting lncRNAs by polyphenols will be a novel and promising strategy in the management of HTN. Herein, we reviewed the effects of polyphenols in HTN. Additionally, we emphasized on the potential effects of polyphenols on regulations of main ncRNAs, which imply the role of polyphenols in regulating ncRNAs in order to exert protective effects and thus proposing them as new targets for HTN treatment.Abbreviations : CVD: cardiovascular disease; BP: blood pressure; HTN: hypertension, lncRNAs: long noncoding RNAs; p38-MAPK: p38-mitogenactivated protein kinase; OPCs: oligomeric procyanidins; GTP: guanosine triphosphate; ROS: reactive oxygen species; cGMP: cyclic guanosine monophosphate; SGC: soluble guanylate cyclase; PI3K: phosphatidylinositol 3-kinase; cGMP: Cyclic GMP; eNOS: endothelial NO synthase; ERK ½: extracellular signal-regulated kinase ½; L-Arg: L-Arginine; MAPK: mitogen-activated protein kinases; NO: Nitric oxide; P: Phosphorus; PDK1: Phosphoinositide-dependent kinase 1; PI3-K: Phosphatidylinositol 3-kinase; PIP2: Phosphatidylinositol diphosphate; ncRNAs: non-protein-coding RNA; miRNAs: microRNAs; OPCs: oligomeric procyanidins; RES: resveratrol; GE: grape extract; T2DM: type 2 diabetes mellitus; IL: interleukin; TNF-α: tumour necrosis factor-alpha; NF-κB: nuclear factor NF-kappa-B; ALP: alkaline phosphatase; PARP1: poly [ADP-ribose] polymerase 1; HIF1a: Hypoxia-inducible-factor 1A; NFATc2: nuclear factor of activated T cells 2; PAD: peripheral artery disease; SHR: spontaneously hypertensive rat; RAAS: renin-angiotensin-aldosterone system; AT₁R: angiotensin type-1 receptor; Nox: NADPH oxidase; HO-1: haem oxygenase-1; JAK/STAT: Janus kinase/signal transducers/activators of the transcription; PNS: panax notoginseng saponin; snoRNA: small nucleolar RNA; hnRNA: heterogeneous nuclear RNA; VSMCs: vascular smooth muscle cells; irf7: interferon regulatory factor 7; limo2: LIM only domain 2; GWAS: genome-wide association study; GAS5: Growth arrest-specific 5; Asb3, Ankyrin repeat and SPCS box containing 3; Chac2: cation transport regulator homolog 2; Pex11b: peroxisomal membrane 11B; Sp5: Sp5 transcription factor; EGCG: epigallocatechin gallate; ApoE: Apo lipoprotein E; ERK-MAP kinase: extracellular signal-regulated kinases-mitogen-activated protein kinase; PAH: pulmonary artery hypertension; PAP: pulmonary arterial pressure; HIF1a: hypoxia-inducible-factor 1A; NFATc2: nuclear factor of activated T cells 2; HMEC-1: Human microvascular endothelial cells; stat2: signal transducers and activators of transcription 2; JNK: c-Jun N-terminal kinase; iNOS: inducible NO synthase. SNP: single nucleotide polymorphism; CAD: coronary artery disease.

MicroRNAs as the Potential Regulators of SARS-CoV-2 Infection and Modifiers of the COVID-19 Clinical Features

The pandemic of coronavirus disease 2019 (COVID-19) warrants the identification of factors that may determine both risk and severity of infection. The factors include microRNAs that have a wide regulatory potential and hence are particularly interesting. The review focuses on the potential roles of human microRNAs and the viral genome as well as microRNAs in SARS-CoV-2 infection and clinical features of COVID-19. The review summarizes the information about the human microRNAs that are thought to specifically bind to the SARS-CoV-2 genome and considers their expression levels in various organs (cells) in both healthy state and pathologies that are risk factors for severe COVID-19. Potential mechanisms whereby SARS-CoV-2 may affect the clinical features of COVID-19 are discussed in brief. The mechanisms include blocking of human microRNAs and RNA-binding proteins, changes in gene expression in infected cells, and possible epigenetic modifications of the human genome with the participation of coronavirus microRNAs.

Non-Coding RNA Networks in Pulmonary Hypertension

Non-coding RNAs (ncRNAs) are involved in various cellular processes. There are several ncRNA classes, including microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs). The detailed roles of these molecules in pulmonary hypertension (PH) remain unclear. We systematically collected and reviewed reports describing the functions of ncRNAs (miRNAs, lncRNAs, and circRNAs) in PH through database retrieval and manual literature reading. The characteristics of identified articles, especially the experimental methods, were carefully reviewed. Furthermore, regulatory networks were constructed using ncRNAs and their interacting RNAs or genes. These data were extracted from studies on pulmonary arterial smooth muscle cells, pulmonary artery endothelial cells, and pulmonary artery fibroblasts. We included 14 lncRNAs, 1 circRNA, 74 miRNAs, and 110 mRNAs in the constructed networks. Using these networks, herein, we describe the current knowledge on the role of ncRNAs in PH. Moreover, these networks actively provide an improved understanding of the roles of ncRNAs in PH. The results of this study are crucial for the clinical application of ncRNAs.

Novel molecular insights and public omics data in pulmonary hypertension

Pulmonary hypertension is a rare disease with high morbidity and mortality which mainly affects women of reproductive age. Despite recent advances in understanding the pathogenesis of pulmonary hypertension, the high heterogeneity in the presentation of the disease among different patients makes it difficult to make an accurate diagnosis and to apply this knowledge to effective treatments. Therefore, new studies are required to focus on translational and personalized medicine to overcome the lack of specificity and efficacy of current management. Here, we review the majority of public databases storing 'omics' data of pulmonary hypertension studies, from animal models to human patients. Moreover, we review some of the new molecular mechanisms involved in the pathogenesis of pulmonary hypertension, including non-coding RNAs and the application of 'omics' data to understand this pathology, hoping that these new approaches will provide insights to guide the way to personalized diagnosis and treatment.

Bone marrow niche crosses paths with BMPs: a road to protection and persistence in CML

Chronic myeloid leukaemia (CML) is a paradigm of precision medicine, being one of the first cancers to be treated with targeted therapy. This has revolutionised CML therapy and patient outcome, with high survival rates. However, this now means an ever-increasing number of patients are living with the disease on life-long tyrosine kinase inhibitor (TKI) therapy, with most patients anticipated to have near normal life expectancy. Unfortunately, in a significant number of patients, TKIs are not curative. This low-level disease persistence suggests that despite a molecularly targeted therapeutic approach, there are BCR-ABL1-independent mechanisms exploited to sustain the survival of a small cell population of leukaemic stem cells (LSCs). In CML, LSCs display many features akin to haemopoietic stem cells, namely quiescence, self-renewal and the ability to produce mature progeny, this all occurs through intrinsic and extrinsic signals within the specialised microenvironment of the bone marrow (BM) niche. One important avenue of investigation in CML is how the disease highjacks the BM, thereby remodelling this microenvironment to create a niche, which enables LSC persistence and resistance to TKI treatment. In this review, we explore how changes in growth factor levels, in particular, the bone morphogenetic proteins (BMPs) and pro-inflammatory cytokines, impact on cell behaviour, extracellular matrix deposition and bone remodelling in CML. We also discuss the challenges in targeting LSCs and the potential of dual targeting using combination therapies against BMP receptors and BCR-ABL1.

Precision medicine: The future of diagnostic approach to pulmonary hypertension?

Pulmonary hypertension (PH) is a common finding that can result from many different pathological conditions. Depending on the etiology, treatment may be quite different, but early diagnosis and correct classification of PH is difficult. With an aging population and recently suggested decreased pulmonary arterial pressure threshold defining PH, we are facing even more diagnostic uncertainties. A new approach to patients' phenotyping is needed. Here we present available data and future perspectives on employing an in-depth analysis of the omics cascade to allow an earlier and more reliable diagnosis and classification of PH. Indeed, with the help of super-fast computing, it became possible to simultaneously consider the levels of thousands of potential biomarkers to find patterns specific for clinically suspected disease. The omics cascade is an invaluable source of information. However, while the genome can be perceived as providing possibilities, transcriptome-as carving them this is metabolome that may tell us 'what is really going on' in an individual living organism. Metabolomics research requires blinded search for characteristic patterns of discreet changes in the levels of detectable metabolites. Since as many as 40,000 various substances are produced as a 'side effect of staying alive', metabolite profiling can be compared to fishing up for organized signals in a universe of chaos. Although difficult, such search for metabolic patterns that might lead to replacing the term biomarker by metabolic fingerprinting in the area of pulmonary circulation has already begun.

Hypoxia Promotes Vascular Smooth Muscle Cell Proliferation through microRNA-Mediated Suppression of Cyclin-Dependent Kinase Inhibitors

Regulation of vascular smooth muscle cell (VSMC) proliferation is essential to maintain vascular homeostasis. Hypoxia induces abnormal proliferation of VSMCs and causes vascular proliferative disorders, such as pulmonary hypertension and atherosclerosis. As several cyclin/cyclin-dependent kinase (CDK) complexes and CDK inhibitors (CKIs) control cell proliferation, in this study, we investigated CKIs involved in the hypoxia-induced proliferation process of human primary pulmonary artery smooth muscle cells to understand the underlying molecular mechanism. We demonstrated that p15, p16, and p21 are downregulated in pulmonary artery smooth muscle cells when exposed to hypoxia. In addition, we identified novel hypoxia-induced microRNAs (hypoxamiRs) including miR-497, miR-1268a, and miR-665 that are upregulated under hypoxia and post-transcriptionally regulate p15, p16, and p21 genes, respectively, by directly targeting their 3'UTRs. These miRNAs promoted the proliferation of VSMCs, and their inhibition decreased VSMC proliferation even in hypoxic conditions. Overall, this study revealed that miRNA-mediated regulatory mechanism of CKIs is essential for hypoxia-induced proliferation of VSMCs. These findings provide insights for a better understanding of the pathogenesis of vascular proliferative disorders.

Analysis of lncRNA-miRNA-mRNA Interactions in Hyper-proliferative Human Pulmonary Arterial Smooth Muscle Cells

We previously reported enhanced proliferation of smooth muscle cells on the combined exposure of HIV proteins and cocaine leading to the development of HIV-pulmonary arterial hypertension. Here, we attempt to comprehensively understand the interactions between long noncoding RNAs (lncRNAs), mRNAs and micro-RNAs (miRNAs) to determine their role in smooth muscle hyperplasia. Differential expression of lncRNAs, mRNAs and miRNAs were obtained by microarray and small-RNA sequencing from HPASMCs treated with and without cocaine and/or HIV-Tat. LncRNA to mRNA associations were conjectured by analyzing their genomic proximity and by interrogating their association to vascular diseases and cancer co-expression patterns reported in the relevant databases. Neuro-active ligand receptor signaling, Ras signaling and PI3-Akt pathway were among the top pathways enriched in either differentially expressed mRNAs or mRNAs associated to lncRNAs. HPASMC with combined exposure to cocaine and Tat (C + T) vs control identified the following top lncRNA-mRNA pairs, ENST00000495536-HOXB13, T216482-CBL, ENST00000602736-GDF7, and, TCONS_00020413-RND1. Many of the down-regulated miRNAs in the HPASMCs treated with C + T were found to be anti-proliferative and targets of up-regulated lncRNAs targeting up-regulated mRNAs, including down-regulation of miR-185, -491 and up-regulation of corresponding ENST00000585387. Specific knock down of the selected lncRNAs highlighted the importance of non-coding RNAs in smooth muscle hyperplasia.

MiR-125a-5p ameliorates monocrotaline-induced pulmonary arterial hypertension by targeting the TGF-β1 and IL-6/STAT3 signaling pathways

Pulmonary vascular remodeling due to excessive proliferation and resistance to apoptosis of pulmonary artery smooth muscle cells (PASMCs) is the hallmark feature of pulmonary arterial hypertension (PAH). Recent evidence suggests that miR-125a-5p plays a role in a rat model of monocrotaline-induced PAH (MCT-PAH); however, the underlying mechanism is currently unknown. Here, we examined the expression profile of miR-125a-5p in MCT-PAH rats and investigated the putative therapeutic effect of miR-125a-5p using the miR-125a-5p agomir. In addition, the miR-125a-5p agomir or antagomir was transfected into rat PASMCs, and proliferation and apoptosis were measured. Activity of the miR-125a-5p target STAT3 was measured using a luciferase reporter assay, and the expression of downstream molecules was measured using RT–qPCR and/or western blot analysis. Importantly, inducing miR-125a-5p expression in vivo slowed the progression of MCT-PAH by reducing systolic pulmonary arterial pressure, the Fulton index, and pulmonary vascular remodeling. Moreover, overexpressing miR-125a-5p inhibited the proliferation and promoted the apoptosis of PASMCs. In addition, stimulating PASMCs with TGF-β1 or IL-6 upregulated miR-125a-5p expression, whereas overexpressing miR-125a-5p reduced TGF-β1 and IL-6 production, as well as the expression of their downstream targets STAT3 and Smad2/3; in contrast, downregulating miR-125a-5p increased TGF-β1 and IL-6 production. Finally, a dual-luciferase reporter assay revealed that miR-125a-5p targets the 3′-UTR of STAT3, suppressing the downstream molecules PCNA, Bcl-2, and Survivin. Taken together, these findings suggest that miR-125a-5p ameliorates MCT-PAH in rats, has a negative feedback regulation with TGF-β1 and IL-6, and regulates the proliferation and apoptosis of PASMCs by directly targeting STAT3.

A study in rats suggests that the small RNA molecule miR-125a-5p is a promising therapeutic target for treating pulmonary arterial hypertension (PAH). This type of high blood pressure is due to the narrowing of arteries that carry blood from the heart to the lungs and at present has no cure. Jieyan Shen at Shanghai Jiao Tong University, China, and colleagues found that PAH lowers the levels of miR-125a-5p in rat pulmonary arteries and that administration of miR-125a-5p as an early preventative treatment reduced disease progression. miR-125a-5p slowed the proliferation of pulmonary artery smooth muscle cells and triggered cell death by directly interacting with a gene expression regulator and reducing the production of certain pro-inflammatory signaling molecules. Targeting miR-125a-5p’s mechanism of action could represent a new treatment approach for this chronic, life-changing disease.

Mitochondrial dysfunction and pulmonary hypertension: cause, effect, or both

Pulmonary hypertension describes a heterogeneous disease defined by increased pulmonary artery pressures, and progressive increase in pulmonary vascular resistance due to pathologic remodeling of the pulmonary vasculature involving pulmonary endothelial cells, pericytes, and smooth muscle cells. This process occurs under various conditions, and although these populations vary, the clinical manifestations are the same: progressive dyspnea, increases in right ventricular (RV) afterload and dysfunction, RV-pulmonary artery uncoupling, and right-sided heart failure with systemic circulatory collapse. The overall estimated 5-yr survival rate is 72% in highly functioning patients, and as low as 28% for those presenting with advanced symptoms. Metabolic theories have been suggested as underlying the pathogenesis of pulmonary hypertension with growing evidence of the role of mitochondrial dysfunction involving the major proteins of the electron transport chain, redox-related enzymes, regulators of the proton gradient and calcium homeostasis, regulators of apoptosis, and mitophagy. There remain more studies needed to characterize mitochondrial dysfunction leading to impaired vascular relaxation, increase proliferation, and failure of regulatory mechanisms. The effects on endothelial cells and resulting interactions with their microenvironment remain uncharted territory for future discovery. Additionally, on the basis of observations that the "plexigenic lesions" of pulmonary hypertension resemble the unregulated proliferation of tumor cells, similarities between cancer pathobiology and pulmonary hypertension have been drawn, suggesting interactions between mitochondria and angiogenesis. Recently, mitochondria targeting has become feasible, which may yield new therapeutic strategies. We present a state-of-the-art review of the role of mitochondria in both the pathobiology of pulmonary hypertension and potential therapeutic targets in pulmonary vascular processes.

Microarray Analysis and Detection of MicroRNAs Associated with Chronic Thromboembolic Pulmonary Hypertension

The aim of this study was to understand the importance of chronic thromboembolic pulmonary hypertension- (CTEPH-) associated microRNAs (miRNAs). miRNAs differentially expressed in CTEPH samples compared with control samples were identified, and the target genes were predicted. The target genes of the key differentially expressed miRNAs were analyzed, and functional enrichment analyses were carried out. Finally, the miRNAs were detected using RT-PCR. Among the downregulated miRNAs, MiR-3148 regulated the most target genes and was significantly enriched in pathways in cancer, glioma, and ErbB signaling pathway. Furthermore, the number of target genes coregulated by miR-3148 and other miRNAs was the most. AR (androgen receptor), a target gene of hsa-miR-3148, was enriched in pathways in cancer. PRKCA (Protein Kinase C Alpha), also a target gene of hsa-miR-3148, was enriched in 15 of 16 KEGG pathways, such as pathways in cancer, glioma, and ErbB signaling pathway. In addition, the RT-PCR results showed that the expression of hsa-miR-3148 in CTEPH samples was significantly lower than that in control samples (P < 0.01). MiR-3148 may play an important role in the development of CTEPH. The key mechanisms for this miRNA may be hsa-miR-3148-AR-pathways in cancer or hsa-miR-3148-PRKCA-pathways in cancer/glioma/ErbB signaling pathway.

MicroRNA-138 and MicroRNA-25 Down-regulate Mitochondrial Calcium Uniporter, Causing the Pulmonary Arterial Hypertension Cancer Phenotype

RATIONALE

Pulmonary arterial hypertension (PAH) is an obstructive vasculopathy characterized by excessive pulmonary artery smooth muscle cell (PASMC) proliferation, migration, and apoptosis resistance. This cancer-like phenotype is promoted by increased cytosolic calcium ([Ca²⁺]_cyto), aerobic glycolysis, and mitochondrial fission.

OBJECTIVES

To determine how changes in mitochondrial calcium uniporter (MCU) complex (MCUC) function influence mitochondrial dynamics and contribute to PAH's cancer-like phenotype.

METHODS

PASMCs were isolated from patients with PAH and healthy control subjects and assessed for expression of MCUC subunits. Manipulation of the pore-forming subunit, MCU, in PASMCs was achieved through small interfering RNA knockdown or MCU plasmid-mediated up-regulation, as well as through modulation of the upstream microRNAs (miRs) miR-138 and miR-25. In vivo, nebulized anti-miRs were administered to rats with monocrotaline-induced PAH.

MEASUREMENTS AND MAIN RESULTS

Impaired MCUC function, resulting from down-regulation of MCU and up-regulation of an inhibitory subunit, mitochondrial calcium uptake protein 1, is central to PAH's pathogenesis. MCUC dysfunction decreases intramitochondrial calcium ([Ca²⁺]_mito), inhibiting pyruvate dehydrogenase activity and glucose oxidation, while increasing [Ca²⁺]_cyto, promoting proliferation, migration, and fission. In PAH PASMCs, increasing MCU decreases cell migration, proliferation, and apoptosis resistance by lowering [Ca²⁺]_cyto, raising [Ca²⁺]_mito, and inhibiting fission. In normal PASMCs, MCUC inhibition recapitulates the PAH phenotype. In PAH, elevated miRs (notably miR-138) down-regulate MCU directly and also by decreasing MCU's transcriptional regulator cAMP response element-binding protein 1. Nebulized anti-miRs against miR-25 and miR-138 restore MCU expression, reduce cell proliferation, and regress established PAH in the monocrotaline model.

CONCLUSIONS

These results highlight miR-mediated MCUC dysfunction as a unifying mechanism in PAH that can be therapeutically targeted.

MiR-125a regulates mitochondrial homeostasis through targeting mitofusin 1 to control hypoxic pulmonary vascular remodeling

Abnormal pulmonary arterial smooth muscle cells (PASMCs) proliferation is an important pathological process in hypoxic pulmonary arterial hypertension. Mitochondrial dynamics and quality control have a central role in the maintenance of the cell proliferation-apoptosis balance. However, the molecular mechanism is still unknown. We used hypoxic animal models, cell biology, and molecular biology to determine the effect of mitofusin 1 (Mfn1) on hypoxia-mediated PASMCs mitochondrial homeostasis. We found that Mfn1 expression was increased in hypoxia, which was crucial for hypoxia-induced mitochondrial dysfunction and smooth muscle cell proliferation as well as hypoxia-stimulated cell-cycle transition from the G₀/G₁ phase to S phase. Subsequently, we studied the role of microRNAs in mitochondrial function associated with PASMC proliferation under hypoxic conditions. The promotive effect of Mfn1 on pulmonary vascular remodeling was alleviated in the presence of miR-125a agomir, and miR-125a antagomir mimicked the hypoxic damage effects to mitochondrial homeostasis. Moreover, in vivo and in vitro treatment with miR-125a agomir protected the pulmonary vessels from mitochondrial dysfunction and abnormal remodeling. In the present study, we determined that mitochondrial homeostasis, particularly Mfn1, played an important role in PASMCs proliferation. MiR-125a, an important underlying factor, which inhibited Mfn1 expression and decreased PASMCs disordered growth during hypoxia. These results provide a theoretical basis for the prevention and treatment of pulmonary vascular remodeling.

KEY MESSAGES

Hypoxia leads to upregulation of mitofusin 1 (Mfn1) both in vivo and in vitro. Mfn1 is involved in hypoxia-induced PASMCs proliferation. Mfn1-mediated mitochondrial homeostasis is regulated by miR-125a. MiR-125a plays a role in PASMCs oxidative phosphorylation and glycolysis.

Aquaporin 1 controls the functional phenotype of pulmonary smooth muscle cells in hypoxia-induced pulmonary hypertension

Vascular remodelling in hypoxia-induced pulmonary hypertension (PH) is driven by excessive proliferation and migration of endothelial and smooth muscle cells. The expression of aquaporin 1 (AQP1), an integral membrane water channel protein involved in the control of these processes, is tightly regulated by oxygen levels. The role of AQP1 in the pathogenesis of PH, however, has not been directly addressed so far. This study was designed to characterize expression and function of AQP1 in pulmonary vascular cells from human arteries and in the mouse model of hypoxia-induced PH. Exposure of human pulmonary vascular cells to hypoxia significantly induced the expression of AQP1. Similarly, levels of AQP1 were found to be upregulated in lungs of mice with hypoxia-induced PH. The functional role of AQP1 was further tested in human pulmonary artery smooth muscle cells demonstrating that depletion of AQP1 reduced proliferation, the migratory potential, and, conversely, increased apoptosis of these cells. This effect was associated with higher expression of the tumour suppressor gene p53. Using the mouse model of hypoxia-induced PH, application of GapmeR inhibitors targeting AQP1 abated the hypoxia-induced upregulation of AQP1 and, of note, reversed PH by decreasing both right ventricular pressure and hypertrophy back to the levels of control mice. Our data suggest an important functional role of AQP1 in the pathobiology of hypoxia-induced PH. These results offer novel insights in our pathogenetic understanding of the disease and propose AQP1 as potential therapeutic in vivo target.

Discerning functional hierarchies of microRNAs in pulmonary hypertension

Pulmonary hypertension (PH) is a multifaceted vascular disease where development and severity are determined by both genetic and environmental factors. Over the past decade, there has been an acceleration of the discovery of molecular effectors that mediate PH pathogenesis, including large numbers of microRNA molecules that are expressed in pulmonary vascular cell types and exert system-wide regulatory functions in all aspects of vascular health and disease. Due to the inherent pleiotropy, overlap, and redundancy of these molecules, it has been challenging to define their integrated effects on overall disease manifestation. In this review, we summarize our current understanding of the roles of microRNAs in PH with an emphasis on potential methods to discern the hierarchical motifs governing their multifunctional and interconnected activities. Deciphering this higher order of regulatory structure will be crucial for overcoming the challenges of developing these molecules as biomarkers or therapeutic targets, in isolation or combination.

Analysis of hypoxia-induced noncoding RNAs reveals metastasis-associated lung adenocarcinoma transcript 1 as an important regulator of vascular smooth muscle cell proliferation

Vascular remodeling, a pathogenic hallmark in pulmonary hypertension, is mainly driven by a dysbalance between proliferation and apoptosis of human pulmonary artery smooth muscle cells. It has previously been shown that microRNAs are involved in the pathogenesis of pulmonary hypertension. However, the role of long noncoding RNAs has not been evaluated. long noncoding RNA expression was quantified in human pulmonary artery smooth muscle cells using PCR arrays and quantitative PCR. Knockdown of genes was performed by transfection of siRNA or GapmeR. Proliferation and migration were measured using BrdU incorporation and wound healing assays. The mouse model of hypoxia-induced PH was used to determine the physiological meaning of identified long noncoding RNAs. The expression of 84 selected long noncoding RNAs was assessed in hypoxic human pulmonary artery smooth muscle cells and the levels of metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) were significantly increased. Depletion of hypoxia-inducible factor 1α abolished the hypoxia-induced upregulation of metastasis-associated lung adenocarcinoma transcript 1 expression. Silencing of MALAT1 significantly decreased proliferation and migration of human pulmonary artery smooth muscle cells. In vivo, MALAT1 expression was significantly increased in lungs of hypoxic mice. Of note, targeting of MALAT1 by GapmeR ameliorated heart hypertrophy in mice with pulmonary hypertension. This is the first report on functional characterization of MALAT1 in the pulmonary vasculature. Our data provide evidence that MALAT1 expression is significantly increased by hypoxia, probably by hypoxia-inducible factor 1α. Intervention experiments confirmed that MALAT1 regulates the proliferative phenotype of smooth muscle cells and silencing of MALAT1 reduced heart hypertrophy in mice with pulmonary hypertension. These data indicate a potential role of MALAT1 in the pathogenesis of pulmonary hypertension. Impact statement Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is a long noncoding RNA that mediates several biological processes. In the context of vascular biology, MALAT1 has been shown to be inducible by hypoxia and to control cell proliferation. These processes are of major importance for the pathophysiology of hypoxia-induced pulmonary hypertension (PH). Until now, the physiological role of MALAT1 in PH remains unclear. By using smooth muscle cells and by employing an established PH mouse model, we provide evidence that hypoxia induces MALAT1 expression. Moreover, depletion of MALAT1 inhibited migration and proliferation of smooth muscle cells, probably by the induction of cyclin-dependent kinase inhibitors. Of note, MALAT1 was significantly increased in mice exposed to hypoxia and silencing of MALAT1 ameliorated heart hypertrophy in mice with hypoxia-induced PH. Since vascular remodeling and right heart failure as a consequence of pulmonary pressure overload is a major problem in PH, these data have implications for our pathogenetic understanding.

MicroRNA-125a-5p alleviates the deleterious effects of ox-LDL on multiple functions of human brain microvessel endothelial cells

MicroRNA-125a-5p (miR-125a-5p) could participate in the pathogenesis of vascular diseases. In this study, we investigated the role of miR-125a-5p in oxidized low-density lipoprotein (ox-LDL)-induced functional changes in human brain microvessel endothelial cells (HBMEC). The reactive oxygen species (ROS) production, nitric oxide (NO) generation, senescence, apoptosis, and functions of HBMEC were analyzed. For mechanism study, the epidermal growth factor receptor (EGFR)/extracellular signal-regulated protein kinase (ERK)/p38 mitogen-activated protein kinase (p38 MAPK) pathway and phosphatidylinositol-3-kinase (PI3K)/serine/threonine kinase (Akt)/endothelial nitric oxide synthase (eNOS) pathway were analyzed. Results showed the following: 1) Expression of miR-125a-5p was reduced in ox-LDL-treated HBMEC. 2) Overexpression of miR-125a-5p protected HBMEC from ox-LDL-induced apoptosis, senescence, ROS production, and NO reduction. 3) Overexpression of miR-125a-5p increased HBMEC proliferation, migration, and tube formation, while decreasing HBMEC adhesion to leukocytes, as well as counteracting the effects of ox-LDL on those functions. 4) The levels of EGFR/ERK/p38 MAPK pathway, PI3K/Akt/eNOS pathway, cleaved caspase-3, and adherent molecular ICAM-1 and VCAM-1 were associated with the effects of ox-LDL on these HBMEC functions. In conclusion, miR-125a-5p could counteract the effects of ox-LDL on various HBMEC functions via regulating the EGFR/ERK/p38 MAPK and PI3K/Akt/eNOS pathways and cleaved caspase-3, ICAM-1, and VCAM-1 expression.

MicroRNA let-7g inhibited hypoxia-induced proliferation of PASMCs via G0/G1 cell cycle arrest by targeting c-myc

AIMS

Pulmonary hypertension (PH) is a proliferative disorder characterized by enhanced proliferation and suppressed apoptosis of intrapulmonary vascular smooth muscle cells. Recently, network-based bioinformatics have identified let-7 family, a tumor suppressive microRNA, regulate multiple interacting targets relevant to PH. However, the role of let-7 in vascular homeostasis in PH remains unknown. Thus, we wanted to investigate the role of let-7 in hypoxia-induced PASMCs proliferation and the underlying mechanism in hypoxic pulmonary hypertension (HPH).

MAIN METHODS

The male Sprague-Dawley (SD) rats were exposed to hypoxia (10% O₂) for 21days to induce HPH. The expression of let-7 was determined by quantitative real-time polymerase chain reaction (qRT-PCR) and in situ hybridization. Primary rat PASMCs were exposed to hypoxia (3% O₂). MTS and EDU were performed to evaluate PASMCs proliferation. The mRNA and protein expression of c-myc, Bmi-1 and p16 were determined by qRT-PCR and Western blotting, respectively. The functions of let-7g on PASMCs proliferation, c-myc, Bmi-1 and p16 expression were assessed by let-7g mimic and inhibitor transfection.

KEY FINDINGS

Among let-7 family members, only let-7b and let-7g were significantly down-regulated in remodeled pulmonary artery in HPH rats. Furthermore, only let-7g level was decreased in hypoxic PASMCs. Either hypoxia or let-7g inhibitor stimulated proliferation of PASMCs, let-7g mimic inhibited hypoxia-induced PASMCs proliferation. C-myc was the target of let-7g in PASMCs. Transfect of let-7g mimic inhibited hypoxia-induced c-myc, Bmi-1 up-regulation and p16 down-regulation, which ultimately controls cell cycle progression.

SIGNIFICANCE

Loss of inhibition on c-myc-Bmi-1-p16 signaling pathway by let-7g may lead to PASMCs proliferation and vascular remodeling in HPH.

A Survey of Strategies to Modulate the Bone Morphogenetic Protein Signaling Pathway: Current and Future Perspectives

Bone morphogenetic proteins (BMPs) constitute the largest subdivision of the TGF-β family of ligands and are unequivocally involved in regulating stem cell behavior. Appropriate regulation of canonical BMP signaling is critical for the development and homeostasis of numerous human organ systems, as aberrations in the BMP pathway or its regulation are increasingly associated with diverse human pathologies. In this review, we provide a wide-perspective on strategies that increase or decrease BMP signaling. We briefly outline the current FDA-approved approaches, highlight emerging next-generation technologies, and postulate prospective avenues for future investigation. We also detail how activating other pathways may indirectly modulate BMP signaling, with a particular emphasis on the relationship between the BMP and Activin/TGF-β pathways.