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MicroRNA biogenesis and RNA-induced gene silencing. Transcription of primary micro RNA (Pri-miRNA) from miRNA genes is followed by cleavage to precursor mRNA (Pre-miRNA) by the Drosha nuclear RNase III. The Pre-miRNA is then exported to the cytoplasm by exportin via nuclear pore. In the cytoplasm, Pre-miRNA is further processed by RNase activity of Dicer to the mature micro RNA duplex. The duplex loads onto Argonaut ribonucleases in the RISC complex and separates. One of the mature miRNA strands (red strand) mediates small interfering RNA silencing by degrading the target mRNA or interfering with translation. The outcome of RISC formation varies with the degree of complementarity of the seed sequence of miRNA and 3’ untranslated regions (UTR) of the target mRNA.
Source publication
During normal lung development and in lung diseases structural cells in the lungs adapt to permit changes in lung function. Fibroblasts, myofibroblasts, smooth muscle, epithelial cells, and various progenitor cells can all undergo phenotypic modulation. In the pulmonary vasculature occlusive vascular lesions that occur in severe pulmonary arterial...
Contexts in source publication
Context 1
... biogenesis and the mechanisms of miRNA-induced gene silencing have been well described, and the basic steps appear to be highly conserved among various cell types. The current consensus on biogenesis is illustrated in Figure 1, and the interested reader is directed to recent reviews of the topic for more detailed description of the process. [14,15] Many miRNA genes are hosted within other genes distributed throughout mammalian genomes. ...Context 2
... tRNA, 5S rRNA and small nuclear RNA genes. Primary miRNA transcripts are capped and polyadenylated then cropped to a ~70 nucleotide precursor (Pre-miRNA) by the nuclear ribonuclease Drosha. After export from the nucleus a cytoplasmic RNase (Dicer) cleaves the loop structure of the pre-miRNA yielding a mature 21~24 nucleotide miRNA duplex (Fig. 1). These processing steps are necessary for proper smooth muscle development based on studies of smooth-muscle restricted knockout of Dicer in mice. Knocking out Dicer is known to inhibit blood vessel maturation and intestinal tract development. [17,18] MiRNA processing is also under control of functionally important extracellular ...Context 3
... proteins including Argonaut family members Ago-1 and Ago-2. The mature dsRNA duplex loads into RNA-induced silencing complexes (RISCs) that mediate posttranscriptional silencing by reducing mRNA stability or by translational block depending on the degree of complementarity of the miRNA seed sequence (nucleotides 2-8) with the target sequence ( Fig. 1). MiRNA tends to be cleaved by Ago-2 when complementarity is perfect, although this is not universally true. The transcript can then be further modified by uridinylation and decapping, and then completely degraded by exonuclease cleavage. When complementarity is imperfect a variety of miRNA/mRNA/RISC structures can form that block ...Citations
... In the present study, the molecular mechanisms underlying the appearance of structural and functional changes and inflammatory processes associated with cardiopulmonary disease were also explored. Recent studies indicated that miRNAs may play a crucial role in the genetic regulation and development of the pathological changes that underlie PAH, including the proliferation, migration, activation of endothelial cells, SMCs, and of fibroblasts, as well as the inflammatory processes [33,78]. Based on these data, we examined the expression of a panel of six miRNAs, including miRNA-124, miRNA-145, miRNA-204, miRNA-210, miRNA-21, and miRNA-214, known to be involved in PAH pathogenesis. ...
Background
Pulmonary hypertension (PH) is a complex multifactorial vascular pathology characterized by an increased pulmonary arterial pressure, vasoconstriction, remodelling of the pulmonary vasculature, thrombosis in situ and inflammation associated with right-side heart failure. Herein, we explored the potential beneficial effects of treatment with siRNA AP-1 on pulmonary arterial hypertension (PAH), right ventricular dysfunction along with perivascular and interstitial fibrosis in pulmonary artery-PA, right ventricle-RV and lung in an experimental animal model of monocrotaline (MCT)-induced PAH.
Methods
Golden Syrian hamsters were divided into: (1) C group-healthy animals taken as control; (2) MCT group obtained by a single subcutaneous injection of 60 mg/kg MCT at the beginning of the experiment; (3) MCT-siRNA AP-1 group received a one-time subcutaneous dose of MCT and subcutaneous injections containing 100 nM siRNA AP-1, every two weeks. All animal groups received water and standard chow ad libitum for 12 weeks.
Results
In comparison with the MCT group, siRNA AP-1 treatment had significant beneficial effects on investigated tissues contributing to: (1) a reduction in TGF-β1/ET-1/IL-1β/TNF-α plasma concentrations; (2) a reduced level of cytosolic ROS production in PA, RV and lung and notable improvements regarding the ultrastructure of these tissues; a decrease of inflammatory and fibrotic marker expressions in PA (COL1A/Fibronectin/Vimentin/α-SMA/CTGF/Calponin/MMP-9), RV and lung (COL1A/CTGF/Fibronectin/α-SMA/F-actin/OB-cadherin) and an increase of endothelial marker expressions (CD31/VE-cadherin) in PA; (4) structural and functional recoveries of the PA [reduced Vel, restored vascular reactivity (NA contraction, ACh relaxation)] and RV (enlarged internal cavity diameter in diastole, increased TAPSE and PRVOFs) associated with a decrease in systolic and diastolic blood pressure, and heart rate; (5) a reduced protein expression profile of AP-1S3/ pFAK/FAK/pERK/ERK and a significant decrease in the expression levels of miRNA-145, miRNA-210, miRNA-21, and miRNA-214 along with an increase of miRNA-124 and miRNA-204.
Conclusions
The siRNA AP-1-based therapy led to an improvement of pulmonary arterial and right ventricular function accompanied by a regression of perivascular and interstitial fibrosis in PA, RV and lung and a down-regulation of key inflammatory and fibrotic markers in MCT-treated hamsters.
... Recent studies indicated that miRNAs may play a crucial role in the genetic regulation and development of the pathological changes that underlie PAH, including the proliferation, migration, activation of endothelial cells, SMCs, and of broblasts, as well as the in ammatory processes [75,76]. Based on these data, we examined the expression of a panel of six miRNAs, including miRNA-124, miRNA-145, miRNA-204, miRNA-210, miRNA-21, and miRNA-214, known to be involved in PAH pathogenesis. ...
Background
Pulmonary hypertension (PH) is a complex multifactorial vascular pathology characterized by an increased pulmonary arterial pressure, vasoconstriction, remodelling of the pulmonary vasculature, thrombosis in situ and inflammation associated with right-side heart failure. Herein, we explored the potential beneficial effects of treatment with siRNA AP-1 on pulmonary arterial hypertension (PAH), right ventricular dysfunction along with perivascular and interstitial fibrosis in pulmonary artery-PA, right ventricle-RV and lung in an experimental animal model of monocrotaline (MCT)-induced PAH.
Methods
Golden Syrian hamsters were divided into: (1) C group-healthy animals taken as control; (2) MCT group obtained by a single subcutaneous injection of 60 mg/kg MCT at the beginning of the experiment; (3) MCT-siRNA AP-1 group received a one-time subcutaneous dose of MCT and subcutaneous injections containing 100nM siRNA AP-1, every two weeks. All animal groups received water and standard chow ad libitum for 12 weeks.
Results
In comparison with the MCT group, siRNA AP-1 treatment had significant beneficial effects on investigated tissues contributing to: (1) a reduction in TGF-β1/ET-1/IL-1β/TNF-α plasma concentrations; (2) a reduced level of cytosolic ROS production in PA, RV and lung and notable improvements regarding the ultrastructure of these tissues; a decrease of inflammatory and fibrotic marker expressions in PA (COL1A/Fibronectin/Vimentin/α-SMA/CTGF/Calponin/MMP-9), RV and lung (COL1A/CTGF/Fibronectin/α-SMA/F-actin/OB-cadherin) and an increase of endothelial marker expressions (CD31/VE-cadherin) in PA; (4) structural and functional recoveries of the PA (reduced Vel, restored vascular reactivity (NA contraction, ACh relaxation)) and RV (enlarged internal cavity diameter in diastole, increased TAPSE and PRVOFs) associated with a decrease in systolic and diastolic blood pressure, and heart rate; (5) a reduced protein expression profile of AP-1S3/ pFAK/FAK/pERK/ERK and a significant decrease in the expression levels of miRNA-145, miRNA-210, miRNA-21, and miRNA-214 along with an increase of miRNA-124 and miRNA-204.
Conclusions
The siRNA AP-1-based therapy led to an improvement of pulmonary arterial and right ventricular function accompanied by a regression of perivascular and interstitial fibrosis in PA, RV and lung and a down-regulation of key inflammatory and fibrotic markers in MCT-treated hamsters.
... Defining which microRNAs control which sets of proteins in normal lung development and function and in lung diseases is a very active area of research. Dysregulation of microRNA expression and function has been described in lung cancer [56], idiopathic pulmonary fibrosis [57,58], cystic fibrosis [59,60], pulmonary hypertension [61], and bronchopulmonary dysplasia [62,63]. Expression of microRNAs becomes dysregulated (either up or down) causing abnormal expression of target genes. ...
Asthma is a chronic inflammatory obstructive lung disease that is stratified into endotypes. Th2 high asthma is due to an imbalance of Th1/Th2 signaling leading to abnormally high levels of Th2 cytokines, IL-4, IL-5, and IL-13 and in some cases a reduction in type I interferons. Some asthmatics express Th2 low, Th1/Th17 high phenotypes with or without eosinophilia. Most asthmatics with Th2 high phenotype respond to beta-adrenergic agonists, muscarinic antagonists, and inhaled corticosteroids. However, 5–10% of asthmatics are not well controlled by these therapies despite significant advances in lung immunology and the pathogenesis of severe asthma. This problem is being addressed by developing novel classes of anti-inflammatory agents. Numerous studies have established efficacy of targeting pro-inflammatory microRNAs in mouse models of mild/moderate and severe asthma. Current approaches employ microRNA mimics and antagonists designed for use in vivo. Chemically modified oligonucleotides have enhanced stability in blood, increased cell permeability, and optimized target specificity. Delivery to lung tissue limits clinical applications, but it is a tractable problem. Future studies need to define the most effective microRNA targets and effective delivery systems. Successful oligonucleotide drug candidates must have adequate lung cell uptake, high target specificity, and efficacy with tolerable off-target effects.
... In the last decades, more than 1000 miRNAs have been found in human cells; some of these miRNAs are highly tissue-specific expression, whereas others are identified as house-keeping functional molecules [17][18][19]. MiR-21 (Fig. 1B), a miRNA overexpressed in almost all types of human malignancy, is involved in multifarious cancer-associated processes, including proliferation, invasion, and metastasis [20][21][22]. A growing number of evidence suggests that miR-21 as an "oncomir" in oncogenesis, which is up-regulation in most detected cancers, including breast, colorectal, pancreatic and glioblastoma cancer [23][24][25]. ...
MiR-21, a non-coding miRNA with 22 nucleotides, plays an important part in the proliferation, invasion, and metastasis of tumor cells. The present study demonstrates that isomers of chiral ruthenium(II) complexes with alkynes (Λ-1 and Δ-1) were synthesized by Songogashira coupling reaction by using microwave-assisted synthetic technology. The isomers can recognize and stabilize miR-21, with the Λ-isomer showing a stronger binding capacity than the Δ-isomer. Further studies showed that both isomers can be uptaken by MDA-MB-231 cells and enriched in the nucleus. Treatment with the Λ-/Δ-isomer downregulated the expression of miR-21. In a word, the development of chiral ruthenium(II) complexes act as potential inhibitors against tumor cells by recognizing, stabilizing, and regulating the expression of miR-21.
... MicroRNAs (miRNAs) are a class of small noncoding RNAs (18-25 nucleotides) that posttranscriptionally regulate the expression of target genes and regulate a variety of cellular processes 21,22 . In general, miRNAs bind to complementary sequences in the 3′ untranslated regions (3′UTR) of target mRNAs, which may lead to target mRNA degradation and/or translational repression 21,22 . ...
Polo-like kinase 1 (Plk1) has been implicated in mitosis, cytokinesis, and proliferation. The mechanisms that regulate Plk1 expression remain to be elucidated. It is reported that miR-100 targets Plk1 in certain cancer cells. Here, treatment with miR-100 did not affect Plk1 protein expression in human airway smooth muscle cells. In contrast, treatment with miR-509 inhibited the expression of Plk1 in airway smooth muscle cells. Exposure to miR-509 inhibitor enhanced Plk1 expression in cells. Introduction of miR-509 reduced luciferase activity of a Plk1 3'UTR reporter. Mutation of miR-509 targeting sequence in Plk1 3'UTR resisted the reduction of the luciferase activity. Furthermore, miR-509 inhibited the PDGF-induced phosphorylation of MEK1/2 and ERK1/2, and cell proliferation without affecting the expression of c-Abl, a tyrosine kinase implicated in cell proliferation. Moreover, we unexpectedly found that vimentin filaments contacted paxillin-positive focal adhesions. miR-509 exposure inhibited vimentin phosphorylation at Ser-56, vimentin network reorganization, focal adhesion formation, and cell migration. The effects of miR-509 on ERK1/2 and vimentin were diminished in RNAi-resistant Plk1 expressing cells treated with miR-509. Taken together, these findings unveil previously unknown mechanisms that miR-509 regulates ERK1/2 and proliferation by targeting Plk1. miR-509 controls vimentin cytoskeleton reorganization, focal adhesion assembly, and cell migration through Plk1.
... They are endogenously expressed in animals, plants, and viruses and have an ability to bind to the 3′-untranslated regions (3′-UTR) of the targeted mRNAs. This interaction prevents protein production by suppressing protein synthesis and/or by initiating mRNA degradation [6,7]. Here, we briefly discuss the canonical mechanism by which miRNAs are processed to their final functional form. ...
MicroRNAs (miRNAs) are small noncoding RNAs that play an integral role in regulating gene expression. Increasing evidence supports the important role of miRNAs in the development and progression of pulmonary arterial hypertension (PAH). The function of miRNAs can also be efficiently and specifically regulated using a number of therapeutic strategies, supporting their potential as targets for the treatment of PAH. In this chapter we briefly describe the biogenesis of miRNAs, summarize our current knowledge of the role of various miRNAs in the pathogenic mechanisms of PAH, introduce strategies of targeting miRNAs to treat the disease, review the preclinical results and potential for using miRNAs for treatment of PAH in in vivo models, and finally discuss the current challenges facing the field to deliver miRNA-targeting therapeutics specifically and efficiently to patients.
... miRNAs negatively regulate the expression of their target genes through translational repression or mRNA degradation (54). Recent studies have provided compelling evidence that miRNAs regulate pulmonary vascular remodeling by controlling endothelial cell (EC) and smooth muscle cell differentiation and proliferation (48,49,51,52,(55)(56)(57). The potential role of miRNAs as master regulators of cell differentiation in physiological and pathological processes in the lung has been reviewed recently (58)(59)(60). However, the precise posttranscriptional mechanisms by which PPARg activation regulates SCD-PH have not been defined. ...
Pulmonary hypertension (PH), a serious complication of sickle cell disease (SCD), causes significant morbidity and mortality. While recent study determined that hemin release during hemolysis triggers endothelial dysfunction in SCD, the pathogenesis of SCD-PH remains incompletely defined. This study examines peroxisome proliferator-activated receptor gamma (PPARγ) regulation in SCD-PH and endothelial dysfunction. PH and right ventricular hypertrophy (RVH) were studied in Townes humanized sickle cell (SS) and littermate control (AA) mice. In parallel studies, SS or AA mice were gavaged with the PPARγ agonist, rosiglitazone (RSG, 10 mg/kg/d) or vehicle for 10 days. In vitro, human pulmonary artery endothelial cells (HPAECs) were treated with vehicle or hemin for 72 hours, and selected HPAECs were treated with RSG. SS mice developed PH and RVH associated with reduced lung levels of PPARγ and increased levels of miR-27a, v-ets avian erythroblastosis virus E26 oncogene homolog 1 (ETS1), endothelin-1 (ET-1), and markers of endothelial dysfunction (platelet/endothelial cell adhesion molecule 1, PECAM1 and E selectin, E-SEL). HPAEC treated with hemin had increased ETS1, miR-27a, ET-1, and endothelial dysfunction and decreased PPARγ levels. These derangements were attenuated by ETS1 knockdown, inhibition of miR-27a, or PPARγ overexpression. In SS mouse lung or in hemin-treated HPAECs, activation of PPARγ with RSG attenuated reductions in PPARγ and increases in miR-27a, ET-1, and markers of endothelial dysfunction. In SCD-PH pathogenesis, ETS1 stimulates increases in miR-27a levels that reduce PPARγ and increase ET-1 and endothelial dysfunction. PPARγ activation attenuated SCD-associated signaling derangements suggesting a novel therapeutic approach to attenuate SCD-PH pathogenesis.
... MicroRNAs (miR) are also involved in fine-tuning the expression of KLF4 and ELK1. For example, miR-143 downregulates ELK1 (15,24,25) and miR-145 and miR-1 reduces KLF4 (15,24,25,46). Since G6PD inhibition increases PKG activity and H 2 O 2 that stimulates miR production (2,11), we postulated that PKG and miR contribute to increase G6PD inhibitioninduced expression of VSMC marker/contractile phenotype proteins. ...
... MicroRNAs (miR) are also involved in fine-tuning the expression of KLF4 and ELK1. For example, miR-143 downregulates ELK1 (15,24,25) and miR-145 and miR-1 reduces KLF4 (15,24,25,46). Since G6PD inhibition increases PKG activity and H 2 O 2 that stimulates miR production (2,11), we postulated that PKG and miR contribute to increase G6PD inhibitioninduced expression of VSMC marker/contractile phenotype proteins. ...
Homeostatic control of vascular smooth muscle cell (VSMC) differentiation is critical for contractile activity and regulation of blood flow. Recently, we reported that pre-contracted blood vessels are relaxed and the phenotype of VSMC is regulated from a synthetic to contractile state by glucose-6-phosphate dehydrogenase (G6PD) inhibition. In the current study, we investigated whether the increase in the expression of VSMC contractile proteins by inhibition and knockdown of G6PD is mediated through a protein kinase G (PKG)-dependent pathway and whether it regulates blood pressure. We found that the expression of VSMC-restricted contractile proteins, myocardin (MYOCD), and miR-1 and miR-143 are increased by G6PD inhibition or knockdown. Importantly, RNA-sequence analysis of aortic tissue from G6PD-deficient mice revealed uniform increases in VSMC-restricted genes, particularly those regulated by the MYOCD-serum response factor (SRF) switch. Conversely, expression of Krüppel-like factor 4 (KLF4) is decreased by G6PD inhibition. Interestingly, the G6PD inhibition-induced expression of miR-1 and contractile proteins was blocked by Rp-β-phenyl-1,N2-etheno-8-bromo-guanosine-3',5'-cyclic monophosphorothioate, a PKG inhibitor. On the other hand, MYOCD and miR-143 levels are increased by G6PD inhibition through a PKG-independent manner. Furthermore, blood pressure was lower in the G6PD-deficient as compared to wild-type mice. Therefore, our results suggest that the expression of VSMC contractile proteins induced by G6PD inhibition occurs via PKG1α-dependent and -independent pathways.
... MicroRNAs (miRs) are a class of small noncoding RNAs that regulate gene expression by either inhibiting mRNA translation or promoting mRNA degradation (8,29). The miR profile is altered in various left heart cardiomyopathies compared with nonfailing hearts (8,14,66). ...
... RV remodeling in response to increased afterload is a complex process that involves 1) changes in expression of cytoskeletal proteins in cardiac myocytes, 2) increase in cardiomyocyte size, and 3) proliferation of noncardiomyocytes in the myocardium (12,13,58). Emerging studies suggest that miRs play a critical role in regulating expression of proteins that are involved in gene regulation, cell proliferation, and cell apoptosis (8,29). Accordingly, using an unbiased quantitative miR microarray analysis, we found that the miRs that increase cardiac fibrosis and hypertrophy found only three miRs (miR-208b, miR-31a-3p, and miR-31a-5p) that were elevated in the LV of PAH rats. ...
Heart failure, a major cause of morbidity and mortality in patients with pulmonary arterial hypertension (PAH), is an outcome of complex biochemical processes. In this study, we determined changes in microRNAs (miRs) in the right and left ventricles of normal and PAH rats. Using an unbiased quantitative miR microarray analysis, we found 1) miR-21-5p, miR-31-5 and 3p, miR-140-5 and 3p, miR-208b-3p, miR-221-3p, miR-222-3p, miR-702-3p, and miR-1298 were upregulated (>2-fold; P < 0.05) in the right ventricle (RV) of PAH compared with normal rats; 2) miR-31-5 and 3p, and miR-208b-3p were upregulated (>2-fold; P < 0.05) in the left ventricle plus septum (LV+S) of PAH compared with normal rats; 3) miR-187-5p, miR-208a-3p, and miR-877 were downregulated (>2-fold; P < 0.05) in the RV of PAH compared with normal rats; and 4) no miRs were up- or downregulated with >2-fold in LV+S compared with RV of PAH and normal. Upregulation of miR-140 and miR-31 in the hypertrophic RV was further confirmed by quantitative PCR. Interestingly, compared with control rats, expression of mitofusin-1 (MFN1), a mitochondrial fusion protein that regulates apoptosis, and which is a direct target of miR-140, was reduced in the RV relative to LV+S of PAH rats. We found a correlation between increased miR-140 and decreased MFN1 expression in the hypertrophic RV. Our results also demonstrated that upregulation of miR-140 and downregulation of MFN1 correlated with increased RV systolic pressure and hypertrophy. These results suggest that miR-140 and MFN1 play a role in the pathogenesis of PAH-associated RV dysfunction.
Listen to this article's corresponding podcast at http://ajpheart.podbean.com/e/mir140-and-right-heart-hypertrophy/ .
... 155,156 Altered expression of miRNAs could result in a dysregulated expression of their target genes, consequently causing or exacerbating several pathological conditions, including cardiovascular diseases and PH. 157,158 Several miRNAs, including miR-21, miR-204, and miR-328, Figure 3. Hypothetical scheme of production and effects of oxidized fatty acids. In the oxidized fatty acid pathway (purple arrows) linoleic acid (LA) and arachidonic acid (AA) in the cytoplasm (shown with an asterisk to indicate the starting point) are enzymatically cleaved through lipoxygenases (LOXs) into hydroperoxyeicosatetraenoid acids (HPETEs) and hydroperoxyoctadecadienoic acids (HPODEs) that are further oxidized into hydroxyeicosatetraenoic acids (HETEs) and hydroxyoctadecadienoic acids (HODEs). ...
Pulmonary arterial hypertension (PAH) is a multifactorial disease characterized by interplay of many cellular, molecular, and genetic events that lead to excessive proliferation of pulmonary cells, including smooth muscle and endothelial cells; inflammation; and extracellular matrix remodeling. Abnormal vascular changes and structural remodeling associated with PAH culminate in vasoconstriction and obstruction of pulmonary arteries, contributing to increased pulmonary vascular resistance, pulmonary hypertension, and right ventricular failure. The complex molecular mechanisms involved in the pathobiology of PAH are the limiting factors in the development of potential therapeutic interventions for PAH. Over the years, our group and others have demonstrated the critical implication of lipids in the pathogenesis of PAH. This review specifically focuses on the current understanding of the role of oxidized lipids, lipid metabolism, peroxidation, and oxidative stress in the progression of PAH. This review also discusses the relevance of apolipoprotein A-I mimetic peptides and microRNA-193, which are known to regulate the levels of oxidized lipids, as potential therapeutics in PAH.
