NF-κB mediated miR-26a regulation in cardiac fibrosis

Serum miR-21 and miR-26a Levels Negatively Correlate with Severity of Cirrhosis in Patients with Chronic Hepatitis B

BACKGROUND AND OBJECTIVE

Accurately evaluating the severity of liver cirrhosis is essential for clinical decision making and disease management. This study aimed to evaluate the value of circulating levels of microRNA (miR)-26a and miR-21 as novel noninvasive biomarkers in detecting severity of cirrhosis in patients with chronic hepatitis B.

METHODS

Thirty patients with clinically diagnosed chronic hepatitis B-related cirrhosis and 30 healthy individuals were selected. The serum levels of miR-26a and miR-21 were quantified by qRT-PCR. Receiver operating characteristic curve analysis was performed to evaluate the sensitivity and specificity of the miRNAs for detecting the severity of cirrhosis.

RESULTS

Serum miR-26a and miR-21 levels were found to be significantly downregulated in patients with severe cirrhosis scored at Child-Pugh class C in comparison to healthy controls (miR-26a p<0.01, and miR-21 p<0.001, respectively). The circulating miR-26a and miR-21 levels in patients were positively correlated with serum albumin concentration but negatively correlated with serum total bilirubin concentration and prothrombin time. Receiver operating characteristic curve analysis revealed that both serum miR-26a and miR-21 levels were associated with a high diagnostic accuracy for patients with cirrhosis scored at Child-Pugh class C (miR-26a Cut-off fold change at ≤0.4, Sensitivity: 84.62%, Specificity: 89.36%, P<0.0001; miR-21 Cut-off fold change at ≤0.6, Sensitivity: 84.62%, Specificity: 78.72%, P<0.0001).

CONCLUSION

Our results indicate that the circulating levels of miR-26a and miR-21 are closely related to the extent of liver decompensation, and the decreased levels are capable of discriminating patients with cirrhosis at Child-Pugh class C from the whole cirrhosis cases.

Angiotensin II Signal Transduction: An Update on Mechanisms of Physiology and Pathophysiology

The renin-angiotensin-aldosterone system plays crucial roles in cardiovascular physiology and pathophysiology. However, many of the signaling mechanisms have been unclear. The angiotensin II (ANG II) type 1 receptor (AT₁R) is believed to mediate most functions of ANG II in the system. AT₁R utilizes various signal transduction cascades causing hypertension, cardiovascular remodeling, and end organ damage. Moreover, functional cross-talk between AT₁R signaling pathways and other signaling pathways have been recognized. Accumulating evidence reveals the complexity of ANG II signal transduction in pathophysiology of the vasculature, heart, kidney, and brain, as well as several pathophysiological features, including inflammation, metabolic dysfunction, and aging. In this review, we provide a comprehensive update of the ANG II receptor signaling events and their functional significances for potential translation into therapeutic strategies. AT₁R remains central to the system in mediating physiological and pathophysiological functions of ANG II, and participation of specific signaling pathways becomes much clearer. There are still certain limitations and many controversies, and several noteworthy new concepts require further support. However, it is expected that rigorous translational research of the ANG II signaling pathways including those in large animals and humans will contribute to establishing effective new therapies against various diseases.

Cardiac fibrosis: new insights into the pathogenesis

Cardiac fibrosis is defined as the imbalance of extracellular matrix (ECM) production and degradation, thus contributing to cardiac dysfunction in many cardiac pathophysiologic conditions. This review discusses specific markers and origin of cardiac fibroblasts (CFs), and the underlying mechanism involved in the development of cardiac fibrosis. Currently, there are no CFs-specific molecular markers. Most studies use co-labelling with panels of antibodies that can recognize CFs. Origin of fibroblasts is heterogeneous. After fibrotic stimuli, the levels of myocardial pro-fibrotic growth factors and cytokines are increased. These pro-fibrotic growth factors and cytokines bind to its receptors and then trigger the activation of signaling pathway and transcriptional factors via Smad-dependent or Smad independent-manners. These fibrosis-related transcriptional factors regulate gene expression that are involved in the fibrosis to amplify the fibrotic response. Understanding the mechanisms responsible for initiation, progression, and amplification of cardiac fibrosis are of great clinical significance to find drugs that can prevent the progression of cardiac fibrosis.

Onset and Progression of Human Osteoarthritis-Can Growth Factors, Inflammatory Cytokines, or Differential miRNA Expression Concomitantly Induce Proliferation, ECM Degradation, and Inflammation in Articular Cartilage?

Osteoarthritis (OA) is a degenerative whole joint disease, for which no preventative or therapeutic biological interventions are available. This is likely due to the fact that OA pathogenesis includes several signaling pathways, whose interactions remain unclear, especially at disease onset. Early OA is characterized by three key events: a rarely considered early phase of proliferation of cartilage-resident cells, in contrast to well-established increased synthesis, and degradation of extracellular matrix components and inflammation, associated with OA progression. We focused on the question, which of these key events are regulated by growth factors, inflammatory cytokines, and/or miRNA abundance. Collectively, we elucidated a specific sequence of the OA key events that are described best as a very early phase of proliferation of human articular cartilage (AC) cells and concomitant anabolic/catabolic effects that are accompanied by incipient pro-inflammatory effects. Many of the reviewed factors appeared able to induce one or two key events. Only one factor, fibroblast growth factor 2 (FGF2), is capable of concomitantly inducing all key events. Moreover, AC cell proliferation cannot be induced and, in fact, is suppressed by inflammatory signaling, suggesting that inflammatory signaling cannot be the sole inductor of all early OA key events, especially at disease onset.

At the heart of programming: the role of micro-RNAs

Epidemiological and experimental observations tend to prove that environment, lifestyle or nutritional challenges influence heart functions together with genetic factors. Furthermore, when occurring during sensitive windows of heart development, these environmental challenges can induce an 'altered programming' of heart development and shape the future heart disease risk. In the etiology of heart diseases driven by environmental challenges, epigenetics has been highlighted as an underlying mechanism, constituting a bridge between environment and heart health. In particular, micro-RNAs which are involved in each step of heart development and functions seem to play a crucial role in the unfavorable programming of heart diseases. This review describes the latest advances in micro-RNA research in heart diseases driven by early exposure to challenges and discusses the use of micro-RNAs as potential targets in the reversal of the pathophysiology.

MicroRNA-135a inhibits cardiac fibrosis induced by isoproterenol via TRPM7 channel

BACKGROUND

Cardiac fibrosis is a crucial factor of heart failure. It has been reported that several microRNAs (miRNAs, miRs) were involved in cardiac fibrosis, however, the role and possible regulatory mechanism of microRNA-135a (miR-135a) in cardiac fibrosis have not been investigated. Here, we explored the regulation mechanism of miR-135a on cardiac fibrosis.

METHODS AND RESULTS

In vitro, cardiac fibroblasts (CFs) from neonatal rats were treated by isoproterenol (ISO) at the final concentration of 10 μM for 24 h and miR-135a expression was decreased obviously. A miR-135a mimic inhibited CFs proliferation and differentiation by down-regulating transient receptor potential melastatin 7 (TRPM7) expression and current, whose effects were reversed by either the addition of miR-135a mimic or silencing TRPM7. In vivo, adult SD rat cardiac fibrosis was induced by subcutaneous administration of ISO (5 mg/kg/day) for 10 days. The expression of Collagen I, α-smooth muscle actin (α-SMA) and TRPM7 were up-regulated while miR-135a was down-regulated. In summary, our results illustrated that TRPM7 channel played an essential role in regulating fibrosis and that miR-135a protected against ISO-induced cardiac fibrosis via TRPM7 channel.

CONCLUSION

MiR-135a inhibits cardiac fibrosis via miR-135a- TRPM7-collagen production pathway.

MicroRNA-30c suppresses the pro-fibrogenic effects of cardiac fibroblasts induced by TGF-β1 and prevents atrial fibrosis by targeting TGFβRII

Atrial fibrosis serves as an important contributor to atrial fibrillation (AF). Recent data have suggested that microRNA-30c (miR-30c) is involved in fibrotic remodelling and cancer development, but the specific role of miR-30c in atrial fibrosis remains unclear. The purpose of this study was to investigate the role of miR-30c in atrial fibrosis and its underlying mechanisms through in vivo and in vitro experiments. Our results indicate that miR-30c is significantly down-regulated in the rat abdominal aortic constriction (AAC) model and in the cellular model of fibrosis induced by transforming growth factor-β1 (TGF-β1). Overexpression of miR-30c in cardiac fibroblasts (CFs) markedly inhibits CF proliferation, differentiation, migration and collagen production, whereas decrease in miR-30c leads to the opposite results. Moreover, we identified TGFβRII as a target of miR-30c. Finally, transferring adeno-associated virus 9 (AAV9)-miR-30c into the inferior vena cava of rats attenuated fibrosis in the left atrium following AAC. These data indicate that miR-30c attenuates atrial fibrosis via inhibition of CF proliferation, differentiation, migration and collagen production by targeting TGFβRII, suggesting that miR-30c might be a novel potential therapeutic target for preventing atrial fibrosis.

Cardioprotection of CAPE-oNO2 against myocardial ischemia/reperfusion induced ROS generation via regulating the SIRT1/eNOS/NF-κB pathway in vivo and in vitro

Caffeic acid phenethyl ester (CAPE) could ameliorate myocardial ischemia/reperfusion injury (MIRI) by various mechanisms, but there hadn’t been any reports on that CAPE could regulate silent information regulator 1 (SIRT1) and endothelial nitric oxide synthase (eNOS) to exert cardioprotective effect. The present study aimed to investigate the cardioprotective potential of caffeic acid o-nitro phenethyl ester (CAPE-oNO₂) on MIRI and the possible mechanism based on the positive control of CAPE. The SD rats were subjected to left coronary artery ischemia /reperfusion (IR) and the H9c2 cell cultured in hypoxia/reoxygenation (HR) to induce the MIRI model. Prior to the procedure, vehicle, CAPE or CAPE-oNO₂ were treated in the absence or presence of a SIRT1 inhibitor nicotinamide (NAM) and an eNOS inhibitor Nω-nitro-L-arginine methyl ester (L-NAME). In vivo, CAPE and CAPE-oNO₂ conferred a cardioprotective effect as shown by reduced myocardial infarct size, cardiac marker enzymes and structural abnormalities. From immunohistochemical and sirius red staining, above two compounds ameliorated the TNF-α release and collagen deposition of IR rat hearts. They could agitate SIRT1 and eNOS expression, and consequently enhance NO release and suppress NF-κB signaling, to reduce the malondialdehyde content and cell necrosis. In vitro, they could inhibit HR-induced H9c2 cell apoptosis and ROS generation by activating SIRT1/eNOS pathway and inhabiting NF-κB expression. Emphatically, CAPE-oNO₂ presented the stronger cardioprotection than CAPE both in vivo and in vitro. However, NAM and L-NAME eliminated the CAPE-oNO₂-mediated cardioprotection by restraining SIRT1 and eNOS expression, respectively. It suggested that CAPE-oNO₂ ameliorated MIRI by suppressing the oxidative stress, inflammatory response, fibrosis and necrocytosis via the SIRT1/eNOS/NF-κB pathway.

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CAPE-oNO₂ exerting cardioprotective potential was firstly synthesized.

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IR-induced ROS increase aggravates inflammation, fibrosis and necrocytosis.

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The SIRT1/eNOS/NF-κB pathway is contributed to MIRI both in vivo and in vitro.

MicroRNA-130a, a Potential Antifibrotic Target in Cardiac Fibrosis

Background

Cardiac fibrosis occurs because of disruption of the extracellular matrix network leading to myocardial dysfunction. Angiotensin II has been implicated in the development of cardiac fibrosis. Recently, microRNAs have been identified as an attractive target for therapeutic intervention in cardiac pathologies; however, the underlying mechanism of microRNAs in cardiac fibrosis remains unclear. MicroRNA‐130a (miR‐130a) has been shown to participate in angiogenesis and cardiac arrhythmia; however, its role in cardiac fibrosis is unknown.

Methods and Results

In this study, we found that miR‐130a was significantly upregulated in angiotensin II‐infused mice. The in vivo inhibition of miR‐130a by locked nucleic acid– based anti‐miR‐130a in mice significantly reduced angiotensin II‐induced cardiac fibrosis. Upregulation of miR‐130a was confirmed in failing human hearts. Overexpressing miR‐130a in cardiac fibroblasts promoted profibrotic gene expression and myofibroblasts differentiation, and the inhibition of miR‐130a reversed the processes. Using the constitutive and dominant negative constructs of peroxisome proliferator‐activated receptor γ 3‐′untranslated region (UTR), data revealed that the protective mechanism was associated with restoration of peroxisome proliferator‐activated receptor γ level leading to the inhibition of angiotensin II‐induced cardiac fibrosis.

Conclusions

Our findings provide evidence that miR‐130a plays a critical role in cardiac fibrosis by directly targeting peroxisome proliferator‐activated receptor γ. We conclude that inhibition of miR‐130a would be a promising strategy for the treatment of cardiac fibrosis.

Biomarkers in patients with myocardial fibrosis

Myocardial fibrosis is observed in many cardiovascular diseases including hypertension, heart failure and cardiomyopathy. Myocardial fibrosis has been proved to be reversible and treatable only under timely intervention, which makes early detection and assessment of fibrosis crucial. Aside from tissue biopsy as the gold standard for the diagnosis of myocardial fibrosis, circulating biomarkers have been adopted as noninvasive assessment of this lesion. Dysregulated collagen deposition is thought to be the major cause of myocardial fibrosis. Collagens, procollagens, TGF-β, TIMP, galectin-3, and microRNAs are thought to be indicators of myocardial fibrosis. In this review, we summarize the molecules that are frequently used as biomarkers in diagnosis of cardiac fibrosis. Mechanisms of fibrosis that they take part in are also introduced.

MicroRNA as a Therapeutic Target in Cardiac Remodeling

MicroRNAs (miRNAs) are small RNA molecules that contain 18–25 nucleotides. The alterations in their expression level play crucial role in the development of many disorders including heart diseases. Myocardial remodeling is the final pathological consequence of a variety of myocardial diseases. miRNAs have central role in regulating pathogenesis of myocardial remodeling by modulating cardiac hypertrophy, cardiomyocytes injury, cardiac fibrosis, angiogenesis, and inflammatory response through multiple mechanisms. The balancing and tight regulation of different miRNAs is a key to drive the cellular events towards functional recovery and any fall in this leads to detrimental effect on cardiac function following various insults. In this review, we discuss the impact of alterations of miRNAs expression on cardiac hypertrophy, cardiomyocytes injury, cardiac fibrosis, angiogenesis, and inflammatory response. We have also described the targets (receptors, signaling molecules, transcription factors, etc.) of miRNAs on which they act to promote or attenuate cardiac remodeling processes in different type cells of cardiac tissues.

Exosomes, DAMPs and miRNA: Features of Stress Physiology and Immune Homeostasis

Psychological/physical stressors and local tissue damage increase inflammatory proteins in tissues and blood in humans and animals, in the absence of pathogenic disease. Stress-evoked cytokine/chemokine responses, or sterile inflammation, can facilitate host survival and/or negatively affect health, depending on context. Recent evidence supports the hypothesis that systemic stress-evoked sterile inflammation is initiated by the sympathetic nervous system, resulting in the elevation of exosome-associated immunostimulatory endogenous danger/damage associated molecular patterns (DAMPs) and a reduction in immunoinhibitory miRNA, which are carried in the circulation to tissues throughout the body. We propose that sterile inflammation should be considered an elemental feature of the stress response and that circulating exosomes transporting immunomodulatory signals, may play a role fundamental role in immune homeostasis.

Arjunolic acid, a peroxisome proliferator-activated receptor α agonist, regresses cardiac fibrosis by inhibiting non-canonical TGF-β signaling

Cardiac hypertrophy and associated heart fibrosis remain a major cause of death worldwide. Phytochemicals have gained attention as alternative therapeutics for managing cardiovascular diseases. These include the extract from the plant Terminalia arjuna, which is a popular cardioprotectant and may prevent or slow progression of pathological hypertrophy to heart failure. Here, we investigated the mode of action of a principal bioactive T. arjuna compound, arjunolic acid (AA), in ameliorating hemodynamic load-induced cardiac fibrosis and identified its intracellular target. Our data revealed that AA significantly represses collagen expression and improves cardiac function during hypertrophy. We found that AA binds to and stabilizes the ligand-binding domain of peroxisome proliferator-activated receptor α (PPARα) and increases its expression during cardiac hypertrophy. PPARα knockdown during AA treatment in hypertrophy samples, including angiotensin II-treated adult cardiac fibroblasts and renal artery-ligated rat heart, suggests that AA-driven cardioprotection primarily arises from PPARα agonism. Moreover, AA-induced PPARα up-regulation leads to repression of TGF-β signaling, specifically by inhibiting TGF-β-activated kinase1 (TAK1) phosphorylation. We observed that PPARα directly interacts with TAK1, predominantly via PPARα N-terminal transactivation domain (AF-1) thereby masking the TAK1 kinase domain. The AA-induced PPARα-bound TAK1 level thereby shows inverse correlation with the phosphorylation level of TAK1 and subsequent reduction in p38 MAPK and NF-κBp65 activation, ultimately culminating in amelioration of excess collagen synthesis in cardiac hypertrophy. In conclusion, our findings unravel the mechanism of AA action in regressing hypertrophy-associated cardiac fibrosis by assigning a role of AA as a PPARα agonist that inactivates non-canonical TGF-β signaling.

Influenza A virus-induced downregulation of miR-26a contributes to reduced IFNα/β production

Innate immunity provides immediate defense against viral infection. Influenza A virus (IAV) is able to get past the first line of defense. Elucidation of the molecular interaction between influenza factors and the newly recognized host players in the innate response might help in our understanding of the root causes of virulence and pathogenicity of IAV. In this study, we show that expression of miR-26a leads to a significant inhibition of IAV replication. miR-26a does not directly target IAV genome. Instead, miR-26a activates the type I interferon (IFN) signaling pathway and promotes the production of IFN-stimulated genes, thus suppressing viral replication. Furthermore, ubiquitin-specific protease 3 (USP3), a negative regulator of type I IFN pathway, is targeted by miR-26a upon IAV challenge. However, miR-26a is significantly downregulated during IAV infection. Thus, downregulation of miR-26a is a new strategy evolved by IAV to counteract cellular antiviral responses. Our findings indicate that delivery of miR-26a may be a potential strategy for anti-IAV therapies.

Ankyrin Repeat Domain 1 Protein: A Functionally Pleiotropic Protein with Cardiac Biomarker Potential

The ankyrin repeat domain 1 (ANKRD1) protein is a cardiac-specific stress-response protein that is part of the muscle ankyrin repeat protein family. ANKRD1 is functionally pleiotropic, playing pivotal roles in transcriptional regulation, sarcomere assembly and mechano-sensing in the heart. Importantly, cardiac ANKRD1 has been shown to be highly induced in various cardiomyopathies and in heart failure, although it is still unclear what impact this may have on the pathophysiology of heart failure. This review aims at highlighting the known properties, functions and regulation of ANKRD1, with focus on the underlying mechanisms that may be involved. The current views on the actions of ANKRD1 in cardiovascular disease and its utility as a candidate cardiac biomarker with diagnostic and/or prognostic potential are also discussed. More studies of ANKRD1 are warranted to obtain deeper functional insights into this molecule to allow assessment of its potential clinical applications as a diagnostic or prognostic marker and/or as a possible therapeutic target.

Sexual dimorphism in the fetal cardiac response to maternal nutrient restriction

Poor maternal nutrition causes intrauterine growth restriction (IUGR); however, its effects on fetal cardiac development are unclear. We have developed a baboon model of moderate maternal undernutrition, leading to IUGR. We hypothesized that the IUGR affects fetal cardiac structure and metabolism. Six control pregnant baboons ate ad-libitum (CTRL)) or 70% CTRL from 0.16 of gestation (G). Fetuses were euthanized at C-section at 0.9G under general anesthesia. Male but not female IUGR fetuses showed left ventricular fibrosis inversely correlated with birth weight. Expression of extracellular matrix protein TSP-1 was increased (p<0.05) in male IUGR. Expression of cardiac fibrotic markers TGFβ, SMAD3 and ALK-1 were downregulated in male IUGRs with no difference in females. Autophagy was present in male IUGR evidenced by upregulation of ATG7 expression and lipidation LC3B. Global miRNA expression profiling revealed 56 annotated and novel cardiac miRNAs exclusively dysregulated in female IUGR, and 38 cardiac miRNAs were exclusively dysregulated in males (p<0.05). Fifteen (CTRL) and 23 (IUGR) miRNAs, were differentially expressed between males and females (p<0.05) suggesting sexual dimorphism, which can be at least partially explained by differential expression of upstream transcription factors (e.g. HNF4α, and NFκB p50). Lipidomics analysis of fetal cardiac tissue exhibited a net increase in diacylglycerol and plasmalogens and a decrease in triglycerides and phosphatidylcholines. In summary, IUGR resulting from decreased maternal nutrition is associated with sex-dependent dysregulations in cardiac structure, miRNA expression, and lipid metabolism. If these changes persist postnatally, they may program offspring for higher later life cardiac risk.

MicroRNA-26a and -26b inhibit lens fibrosis and cataract by negatively regulating Jagged-1/Notch signaling pathway

Fibrosis is a chronic process involving development and progression of multiple diseases in various organs and is responsible for almost half of all known deaths. Epithelial–mesenchymal transition (EMT) is the vital process in organ fibrosis. Lens is an elegant biological tool to investigate the fibrosis process because of its unique biological properties. Using gain- and loss-of-function assays, and different lens fibrosis models, here we demonstrated that microRNA (miR)-26a and miR-26b, members of the miR-26 family have key roles in EMT and fibrosis. They can significantly inhibit proliferation, migration, EMT of lens epithelial cells and lens fibrosis in vitro and in vivo. Interestingly, we revealed that the mechanisms of anti-EMT effects of miR-26a and -26b are via directly targeting Jagged-1 and suppressing Jagged-1/Notch signaling. Furthermore, we provided in vitro and in vivo evidence that Jagged-1/Notch signaling is activated in TGFβ2-stimulated EMT, and blockade of Notch signaling can reverse lens epithelial cells (LECs) EMT and lens fibrosis. Given the general involvement of EMT in most fibrotic diseases, cancer metastasis and recurrence, miR-26 family and Notch pathway may have therapeutic uses in treating fibrotic diseases and cancers.

Sphingosine 1-Phosphate Receptors: Do They Have a Therapeutic Potential in Cardiac Fibrosis?

Sphingosine 1-phosphate (S1P) is a bioactive lipid that is characterized by a peculiar mechanism of action. In fact, S1P, which is produced inside the cell, can act as an intracellular mediator, whereas after its export outside the cell, it can act as ligand of specific G-protein coupled receptors, which were initially named endothelial differentiation gene (Edg) and eventually renamed sphingosine 1-phosphate receptors (S1PRs). Among the five S1PR subtypes, S1PR1, S1PR2 and S1PR3 isoforms show broad tissue gene expression, while S1PR4 is primarily expressed in immune system cells, and S1PR5 is expressed in the central nervous system. There is accumulating evidence for the important role of S1P as a mediator of many processes, such as angiogenesis, carcinogenesis and immunity, and, ultimately, fibrosis. After a tissue injury, the imbalance between the production of extracellular matrix (ECM) and its degradation, which occurs due to chronic inflammatory conditions, leads to an accumulation of ECM and, consequential, organ dysfunction. In these pathological conditions, many factors have been described to act as pro- and anti-fibrotic agents, including S1P. This bioactive lipid exhibits both pro- and anti-fibrotic effects, depending on its site of action. In this review, after a brief description of sphingolipid metabolism and signaling, we emphasize the involvement of the S1P/S1PR axis and the downstream signaling pathways in the development of fibrosis. The current knowledge of the therapeutic potential of S1PR subtype modulators in the treatment of the cardiac functions and fibrinogenesis are also examined.

Curcumin induces G2/M arrest, apoptosis, NF-κB inhibition, and expression of differentiation genes in thyroid carcinoma cells

PURPOSE

The therapy of unresectable advanced thyroid carcinomas shows unfavorable outcome. Constitutive nuclear factor-κB (NF-κB) activation in thyroid carcinomas frequently contributes to therapeutic resistance; the radioiodine therapy often fails due to the loss of differentiated functions in advanced thyroid carcinomas. Curcumin is known for its anticancer properties in a series of cancers, but only few studies have focused on thyroid cancer. Our aim was to evaluate curcumin's molecular mechanisms and to estimate if curcumin could be a new therapeutic option in advanced thyroid cancer.

METHODS

Human thyroid cancer cell lines TPC-1 (papillary), FTC-133 (follicular), and BHT-101 (anaplastic) were treated with curcumin. Using real-time PCR analysis, we investigated microRNA (miRNA) and mRNA expression levels. Cell cycle, Annexin V/PI staining, and caspase-3 activity analysis were performed to detect apoptosis. NF-κB p65 activity and cell proliferation were analyzed using appropriate ELISA-based colorimetric assay kits.

RESULTS

Treatment with 50 μM curcumin significantly increased the mRNA expression of the differentiation genes thyroglobulin (TG) and sodium iodide symporter (NIS) in all three cell lines and induced inhibition of cell proliferation, apoptosis, and decrease of NF-κB p65 activity. The miRNA expression analyses showed a significant deregulation of miRNA-200c, -21, -let7c, -26a, and -125b, known to regulate cell differentiation and tumor progression. Curcumin arrested cell growth at the G2/M phase.

CONCLUSIONS

Curcumin increases the expression of redifferentiation markers and induces G2/M arrest, apoptosis, and downregulation of NF-κB activity in thyroid carcinoma cells. Thus, curcumin appears to be a promising agent to overcome resistance to the conventional cancer therapy.

Identification of a reference gene for the quantification of mRNA and miRNA expression during skin wound healing

AIM

Wound healing is a coordinated process to restore tissue homeostasis and reestablish the protective barrier of the skin. miRNAs may modulate the expression of target genes to contribute to repair processes, but due to the complexity of the tissue it is challenging to quantify gene expression during the distinct phases of wound repair. Here, we aimed to identify a common reference gene to quantify changes in miRNA and mRNA expression during skin wound healing.

METHODS

Quantitative real-time PCR and bioinformatic analysis tools were used to identify suitable reference genes during skin repair and their reliability was tested by studying the expression of mRNAs and miRNAs.

RESULTS

Morphological assessment of wounds showed that the injury model recapitulates the distinct phases of skin repair. Non-degraded RNA could be isolated from skin and wounds and used to study the expression of non-coding small nuclear RNAs during wound healing. Among those, RNU6B was most constantly expressed during skin repair. Using this reference gene we could confirm the transient upregulation of IL-1β and PTPRC/CD45 during the early phase as well as the increased expression of collagen type I at later stages of repair and validate the differential expression of miR-204, miR-205, and miR-31 in skin wounds. In contrast to Gapdh the normalization to multiple reference genes gave a similar outcome.

CONCLUSION

RNU6B is an accurate alternative normalizer to quantify mRNA and miRNA expression during the distinct phases of skin wound healing when analysis of multiple reference genes is not feasible.

The role of microRNAs in heart failure

MicroRNAs are small non-coding RNA molecules that regulate gene expression by inhibiting mRNA translation and/or inducing mRNA degradation. In the past decade, many in vitro and in vivo studies have explored the involvement of microRNAs in various cardiovascular diseases. In this paper, studies focused upon the target genes and functionality of miRNAs in the pathophysiological processes of heart failure are reviewed. The selected miRNAs are categorized according to the biological relevance of their target genes in relation to four cardiovascular pathologies, namely angiogenesis, cardiac hypertrophy, fibrosis and apoptosis. This review illustrates the involvement of miRNAs in different biological signaling pathways and provides an overview of current understanding of the roles of miRNAs in cardiovascular health and diseases. This article is part of a Special Issue entitled: Genetic and epigenetic control of heart failure - edited by Jun Ren & Megan Yingmei Zhang.

The coordinated roles of miR-26a and miR-30c in regulating TGFβ1-induced epithelial-to-mesenchymal transition in diabetic nephropathy

MicroRNAs (miRNAs) play vital roles in the development of diabetic nephropathy. Here, we compared the protective efficacies of miR-26a and miR-30c in renal tubular epithelial cells (NRK-52E) and determined whether they demonstrated additive effects in the attenuation of renal fibrosis. TGFβ1 suppressed miR-26a and miR-30c expression but up-regulated pro-fibrotic markers in NRK-52E cells, and these changes were also found in the kidney cortex of 40-week-old diabetic Otsuka Long-Evans Tokushima fatty (OLETF) rats. Bioinformatic analyses and luciferase assays further demonstrated that both miR-26a and miR-30c targeted connective tissue growth factor (CTGF); additionally, Snail family zinc finger 1 (Snail1), a potent epithelial-to-mesenchymal transition (EMT) inducer, was targeted by miR-30c. Overexpression of miR-26a and miR-30c coordinately decreased CTGF protein levels and subsequently ameliorated TGFβ1-induced EMT in NRK-52E cells. Co-silencing of miR-26a and miR-30c exhibited the opposite effect. Moreover, miR-26a and miR-30c co-silenced CTGF to decrease ERK1/2 and p38 MAPK activation. Furthermore, miR-26a was up-regulated in urinary extracellular vesicles of diabetic nephropathy patients. Our study provides evidence for the cooperative roles of miR-26a and miR-30c in the pathogenesis of diabetic nephropathy, and the co-targeting of miR-26a and miR-30c could provide a new direction for diabetic nephropathy treatment.

Emerging drugs and therapeutics for systemic sclerosis

INTRODUCTION

Treatment of systemic sclerosis (SSc) is challenging despite advances in medical therapeutics for other rheumatologic diseases. Significant disease modifying therapy is lacking for most patients with SSc, due to the heterogeneous multisystem nature of SSc and its complex pathophysiology. The emergence of organ based management strategies has provided guidance in patient care as well as research and drug development. Areas covered: Design and development of new compounds focused on the underlying fibrotic disease processes have been sparse. Therefore, organ based strategies with targeted approaches have been directed towards the most devastating and life threatening features of systemic sclerosis. These include pulmonary arterial hypertension, interstitial lung disease, peripheral vasculopathy and skin thickening. In this context, new treatment regimens using older drugs as well as discovery of novel compounds based on recent insights of the disease pathophysiology are discussed. Expert opinion: Systemic sclerosis is a heterogeneous rare disease that carries a high burden of morbidity and mortality. Organ based management strategies have improved the natural history of systemic sclerosis using targeted interventions or strategies, particularly vascular features. However, more research is required to better understand disease mechanisms, including an ultimate unifying pathway that explains the multisystem nature of systemic sclerosis.

The role of miRNAs in cardiovascular disease risk factors

Coronary artery disease and atherosclerosis are complex pathologies that develop over time due to genetic and environmental factors. Differential expression of miRNAs has been identified in patients with coronary artery disease and atherosclerosis, however, their association with cardiovascular disease risk factors, including hyperlipidemia, hypertension, obesity, diabetes, lack of physical activity and smoking, remains unclear. This review examines the role of miRNAs as either biomarkers or potential contributors to the pathophysiology of these aforementioned risk factors. It is intended to provide an overview of the published literature which describes alterations in miRNA levels in both human and animal studies of cardiovascular risk factors and when known, the possible mechanism by which these miRNAs may exert either beneficial or deleterious effects. The intent of this review is engage clinical, translational, and basic scientists to design future collaborative studies to further elucidate the potential role of miRNAs in cardiovascular diseases.

MicroRNAs in idiopathic pulmonary fibrosis: involvement in pathogenesis and potential use in diagnosis and therapeutics

MicroRNAs (miRNAs) are a class of phylogenetically conserved, non-coding short RNAs, 19-22 nt in length which suppress protein expression through base-pairing with the 3'-untranslated region of target mRNAs. miRNAs have been found to participate in cell proliferation, differentiation and apoptosis. Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, and high lethality fibrotic lung disease for which currently there is no effective treatment. Some miRNAs have been reported to be involved in the pathogenesis of pulmonary fibrosis. In this review, we discuss the role of miRNAs in the pathogenesis, diagnosis and treatment of IPF.

Mechanical stretch regulates microRNA expression profile via NF-κB activation in C2C12 myoblasts

MicroRNAs (miRNAs/miRs) and nuclear factor (NF)-κB activation are involved in mechanical stretch-induced skeletal muscle regeneration. However, there are a small number of miRNAs that have been reported to be associated with NF‑κB activation during mechanical stretch-induced myogenesis. In the present study, C2C12 myoblasts underwent cyclic mechanical stretch in vitro, to explore the relationship between miRNA expression and NF‑κB activation during stretch-mediated myoblast proliferation. The results revealed that 10% deformation, 0.125 Hz cyclic mechanical stretch could promote myoblast proliferation. The miRNA expression profile was subsequently altered; miR‑500, ‑1934, ‑31, ‑378, ‑331 and ‑5097 were downregulated, whereas miR‑1941 was upregulated. These miRNAs were all involved in stretch‑mediated myoblast proliferation. Notably, the expression of these miRNAs was reversed following treatment of 0.125 Hz mechanically stretched C2C12 cells with NF‑κB inhibitors, which was accompanied by C2C12 cell growth suppression. Therefore, the present study is the first, to the best of our knowledge, to demonstrate that the NF‑κB‑dependent miRNA profile is associated with mechanical stretch-induced myoblast proliferation.

Crucial Role of miR-433 in Regulating Cardiac Fibrosis

Dysregulation of microRNAs has been implicated in many cardiovascular diseases including fibrosis. Here we report that miR-433 was consistently elevated in three models of heart disease with prominent cardiac fibrosis, and was enriched in fibroblasts compared to cardiomyocytes. Forced expression of miR-433 in neonatal rat cardiac fibroblasts increased proliferation and their differentiation into myofibroblasts as determined by EdU incorporation, α-SMA staining, and expression levels of fibrosis-associated genes. Conversely, inhibition of miR-433 exhibited opposite results. AZIN1 and JNK1 were identified as two target genes of miR-433. Decreased level of AZIN1 activated TGF-β1 while down-regulation of JNK1 resulted in activation of ERK and p38 kinase leading to Smad3 activation and ultimately cardiac fibrosis. Importantly, systemic neutralization of miR-433 or adeno-associated virus 9 (AAV9)-mediated cardiac transfer of a miR-433 sponge attenuated cardiac fibrosis and ventricular dysfunction following myocardial infarction. Thus, our work suggests that miR-433 is a potential target for amelioration of cardiac fibrosis.

Plasma miR-26a as a Diagnostic Biomarker Regulates Cytokine Expression in Systemic Juvenile Idiopathic Arthritis

Objective.

We sought to identify specific microRNA (miRNA) for systemic juvenile idiopathic arthritis (sJIA) and to determine the involvement of these miRNA in regulating the expression of cytokines.

Methods.

Microarray profiling was performed to identify differentially expressed miRNA in sJIA plasma. Levels of candidate miRNA and mRNA were assessed by real-time PCR, and cytokines were measured by ELISA. Dual-luciferase reporter assay was used to validate the direct interaction between miR-26a and interleukin 6 (IL-6).

Results.

Forty-eight miRNA were differentially expressed in the plasma of patients with sJIA compared with healthy controls (HC). Five miRNA were selected for further validation. The expression level of miR-26a was exclusively elevated in the plasma of patients with sJIA as compared with 4 rheumatic diseases and 2 subtypes of JIA (oligoarticular and polyarticular). The levels of IL-6, IL-1β, and tumor necrosis factor-α in the plasma of patients with sJIA were increased, and only IL-6 presented a positive correlation with miR-26a (r = 0.539, p < 0.0001). After stimulation with IL-6, miR-26a expression was upregulated in THP-1 cells, while the supernatant level of IL-6 was downregulated by transfection of miR-26a mimics. Consistently, direct target relationship between miR-26a and IL-6 was confirmed.

Conclusion.

This study demonstrates that miR-26a is expressed specifically and highly in sJIA plasma and suggests that miR-26a may regulate the levels of cytokines in sJIA. Our findings highlight miR-26a as a potential biomarker for the diagnosis as well as differential diagnosis of sJIA.

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.

Identification of cardiomyopathy associated circulating miRNA biomarkers in patients with muscular dystrophy using a complementary cardiovascular magnetic resonance and plasma profiling approach

BACKGROUND

Duchenne and Becker muscular dystrophy (DMD and BMD) are X-chromosomal recessive neuromuscular disorders that are caused by mutations in the dystrophin gene and characterized by cardiac involvement. Circulating microRNAs (miRNAs) have been proposed as diagnostic biomarkers for various cardiovascular diseases. However, circulating miRNAs reflecting the presence and/or disease severity of cardiac involvement in DMD/BMD patients have not been described so far.

METHODS

Sixty-three male patients with known MD and 26 age-matched healthy male controls were prospectively enrolled. All MD patients and controls underwent comprehensive cardiovascular magnetic resonance (CMR) studies as well as venous blood sampling on the same day.

RESULTS

An impaired left ventricular (LV) systolic function (defined as LV-EF <55 %) was detected in 29 (46 %) and presence of late gadolinium enhancement (LGE) indicative of myocardial fibrosis in 48 (76 %) MD patients with an exclusively non-ischemic pattern. Whereas no significant differences were observed for the 27 selected circulating miRNAs in MD patients with abnormal CMR findings (comprising structural and/or functional impairments) compared to those with completely normal CMR studies, a significant up-regulation of three miRNAs was observed in LGE-positive MD patients compared to LGE-negative ones: miR-222 (1.8-fold, p = 0.035), miR-26a (2.1-fold, p = 0.03) and miR-378a-5p (2.4-fold, p = 0.026). A signature of these three miRNAs (miR-26a, miR-222 and miR-378a-5p) resulted in an area under the curve (AUC) value of 0.74 for the diagnosis of LGE-positive MD patients. In a multivariable model, three independent predictors for LGE presence were identified comprising not only clinical and laboratory markers (LV-EF: OR 0.47, 95 % CI 0.24-0.89, p = 0.021 and elevated hs-Trop: OR 2559, 95 % CI 2.97-22.04*10(5), p = 0.023) but also the circulating miR-222 (OR 938, 95 % CI 938.46, 3.56-24.73*10(4), p = 0.016).

CONCLUSIONS

Up-regulation of circulating miRNAs miR-222, miR-26a and miR-378a-5p indicates the presence of myocardial scars in MD patients. Plasma miR-222 appears to be a promising novel biomarker reflecting structural - but not functional - cardiac alterations in MD patients.

miR-19a, -19b, and -26b Mediate CTGF Expression and Pulmonary Fibroblast Differentiation

Although microRNA (miRNA) dysregulation with intracellular signaling cascade disruption has been demonstrated in the pathophysiology of pulmonary fibrosis, the relationship between miRNAs and intracellular signaling cascades in pulmonary fibrosis remains unclear. Using the human embryonic lung fibroblast cell line WI-38, we observed endothelin-1 (ET-1)- and thrombin-induced expression of the differentiation markers α-smooth muscle actin (α-SMA) and vimentin along with increased connective tissue growth factor (CTGF) protein expression. Decreased CTGF protein expression by CTGF siRNA significantly blocked ET-1- and thrombin-induced α-SMA and vimentin expression in WI-38 cells. Activation of the mitogen-activated protein kinases (MAPKs) extracellular signal-regulated kinase ERK, c-Jun N-terminal kinase (JNK), and p38 contributed to ET-1- and thrombin-induced CTGF, α-SMA, and vimentin expression in WI-38 cells. TargetScan Human, miRanda, and PicTar prediction algorithms were used to predict miRNAs with binding sites in the 3' untranslated region (UTR) of CTGF mRNA. miR-19a, -19b, and -26b were candidate miRNAs of CTGF. Direct binding of the candidate miRNAs to the 3'-UTR of CTGF mRNA was verified through luciferase assay by using SV40-promoter-IRES-driven luciferase containing the 3'-UTR of CTGF mRNA as a reporter plasmid. ET-1 and thrombin reduced candidate miRNA levels. Candidate miRNA overexpression significantly suppressed ET-1- and thrombin-induced CTGF expression and reduced α-SMA and vimentin expression in the WI-38 cells. Furthermore, candidate miRNA levels were decreased in the lung tissues of mice with bleomycin-induced pulmonary fibrosis, and intratracheal application of miR-19a, -19b, and 26b reduced the pulmonary fibrotic severity induced by bleomycin. This study is the first to demonstrate crosstalk between MAPK activation and reduction in miR-19a, -19b, and -26b expression leading to lung fibroblast differentiation. J. Cell. Physiol. 231: 2236-2248, 2016. © 2016 Wiley Periodicals, Inc.

Comparative transcriptome profiling of the injured zebrafish and mouse hearts identifies miRNA-dependent repair pathways

Aims

The adult mammalian heart has poor regenerative capacity. In contrast, the zebrafish heart retains a robust capacity for regeneration into adulthood. These distinct responses are consequences of a differential utilization of evolutionary-conserved gene regulatory networks in the damaged heart. To systematically identify miRNA-dependent networks controlling cardiac repair following injury, we performed comparative gene and miRNA profiling of the cardiac transcriptome in adult mice and zebrafish.

Methods and results

Using an integrated approach, we show that 45 miRNA-dependent networks, involved in critical biological pathways, are differentially modulated in the injured zebrafish vs. mouse hearts. We study, more particularly, the miR-26a-dependent response. Therefore, miR-26a is down-regulated in the fish heart after injury, whereas its expression remains constant in the mouse heart. Targets of miR-26a involve activators of the cell cycle and Ezh2, a component of the polycomb repressive complex 2 (PRC2). Importantly, PRC2 exerts repressive functions on negative regulators of the cell cycle. In cultured neonatal cardiomyocytes, inhibition of miR-26a stimulates, therefore, cardiomyocyte proliferation. Accordingly, miR-26a knockdown prolongs the proliferative window of cardiomyocytes in the post-natal mouse heart.

Conclusions

This novel strategy identifies a series of miRNAs and associated pathways, in particular miR-26a, which represent attractive therapeutic targets for inducing repair in the injured heart.

Noncoding RNA as regulators of cardiac fibrosis: current insight and the road ahead

Cardiac fibrosis is an important pathological feature of cardiac remodeling in heart diseases. The molecular mechanisms of cardiac fibrosis are unknown. Genomic analyses estimated that many noncoding DNA regions generate noncoding RNAs (ncRNAs). ncRNAs have emerged as key molecular players in the regulation of gene expression in different biological processes. Recent studies have started to reveal the importance of ncRNAs in heart development and suggest also an involvement in cardiac fibrosis. These molecules are emerging as important regulators of cellular process. Here, we review particularly focuses on the involvement of two large families of ncRNAs, namely microRNAs (miRNAs) and long noncoding RNAs (LncRNAs) in the regulation of cardiac fibrosis. Furthermore, we review the functions and role of ncRNAs in cardiac biology and discuss these reports and the therapeutic potential of ncRNAs for cardiac fibrosis associated with fibroblast activation and proliferation.

Effect of miR-29a inhibition on ventricular hypertrophy induced by pressure overload

To investigate whether inhibition of miR-29a functioning prevents the hypertension-induced ventricular hypertrophy and fibrosis. Patients diagnosed with hypertension and left ventricular hypertrophy were recruited for the study. Serum levels of miR-29a were determined by RT-PCR. Levels of serum matrix metalloproteinase-9 (MMP-9), collagen type I and III (PINP and PIIINP) were determined by double-antibody enzyme-linked immunosorbent assay. Mouse model of transverse aortic constriction (TAC) was established. 7 days after surgery, TAC mice were injected intraperitoneally with antagomir miR-29a or vehicle once a day for 3 days. After 4 weeks of surgery, animals were sacrificed and cross-sections of the hearts were stained and evaluated for hypertrophy and fibrosis. The expression of the protein markers of hypertrophy and fibrosis was determined by immunoblotting. The serum level of miR-29a in hypertensive patients with left ventricular hypertrophy was significantly higher than those in patients with hypertension alone (p < 0.05). The levels of serum miR-29a were positively correlated with those of PINP, PIIINP, and MMP-9 (r = 0.58, 0.45, 0.66, respectively, p < 0.05). In mouse model of pressure overload, the antagomir miR-29a was found to significantly suppress the hypertrophy of cardiomyocytes and the expression of ANP and β-MHC, the hypertrophy indices. Also, the ventricular fibrosis and expression of the marker proteins were blocked in antagomir treated mice. The inhibition of miR-29a was found to be effective in improving the ventricular remodeling and hypertrophy caused by pressure overload.

RNA sequencing reveals a depletion of collagen targeting microRNAs in Dupuytren's disease

Background

Dupuytren’s disease is an inherited disorder in which patients develop fibrotic contractures of the hand. Current treatment strategies include surgical excision or enzymatic digestion of fibrotic tissue. MicroRNAs, which are key posttranscriptional regulators of genes expression, have been shown to play an important regulatory role in disorders of fibrosis. Therefore in this investigation, we apply high throughput next generation RNA sequencing strategies to characterize microRNA expression in diseased and healthy palmar fascia to elucidate molecular mechanisms responsible for pathogenic fibrosis.

Methods

We applied high throughput RNA sequencing techniques to quantify the expression of all known human microRNAs in Dupuytren’s and control palmar fascia. MicroRNAs that were differentially expressed between diseased and healthy tissue samples were used for computational target prediction using the bioinformatics tool ComiR. Molecular pathways that were predicted to be differentially expressed based on computational analysis were validated by performing RT-qPCR on RNA extracted from diseased and non-diseased palmar fascia biopsies.

Results

A comparison of microRNAs expressed in Dupuytren’s fascia and control fascia identified 74 microRNAs with a 2-fold enrichment in Dupuytren’s tissue, and 32 microRNAs with enrichment in control fascia. Computational target prediction for differentially expressed microRNAs indicated preferential targeting of collagens and extracellular matrix related proteins in control palmar fascia. RT-qPCR confirmed the decreased expression of microRNA targeted collagens in control palmar fascia tissues.

Discussion

Control palmar fascia show decreased expression of mRNAs encoding collagens that are preferentially targeted by microRNAs enriched in non-diseased fascia. Thus alterations in microRNA regulatory networks may play an important role in driving the pathogenic fibrosis seen in Dupuytren’s disease via direct regulatory effects on extracellular matrix protein synthesis.

Conclusion

Dupuytren’s fascia and healthy palmar fascia can be distinguished by unique microRNA profiles, which are predicted to preferentially target collagens and other extracellular matrix proteins.

Electronic supplementary material

The online version of this article (doi:10.1186/s12920-015-0135-8) contains supplementary material, which is available to authorized users.

Cardiovascular and Cerebrovascular Disease Associated microRNAs Are Dysregulated in Placental Tissues Affected with Gestational Hypertension, Preeclampsia and Intrauterine Growth Restriction

Aims

To demonstrate that pregnancy-related complications are associated with alterations in cardiovascular and cerebrovascular microRNA expression. Gene expression of 32 microRNAs (miR-1-3p, miR-16-5p, miR-17-5p, miR-20a-5p, miR-20b-5p, miR-21-5p, miR-23a-3p, miR-24-3p, miR-26a-5p, miR-29a-3p, miR-33a-5p, miR-92a-3p, miR-100-5p, miR-103a-3p, miR-122-5p, miR-125b-5p, miR-126-3p, miR-130b-3p, miR-133a-3p, miR-143-3p, miR-145-5p, miR-146a-5p, miR-155-5p, miR-181a-5p, miR-195-5p, miR-199a-5p, miR-208a-3p, miR-210-3p, miR-221-3p, miR-342-3p, miR-499a-5p, and miR-574-3p) was assessed in placental tissues, compared between groups (35 gestational hypertension, 80 preeclampsia, 35 intrauterine growth restriction and 20 normal pregnancies) and correlated with the severity of the disease with respect to clinical signs, delivery date, and Doppler ultrasound parameters. Initially, selection and validation of endogenous controls for microRNA expression studies in placental tissues affected by pregnancy-related complications have been carried out.

Results

The expression profile of microRNAs was different between pregnancy-related complications and controls. The up-regulation of miR-499a-5p was a common phenomenon shared between gestational hypertension, preeclampsia, and intrauterine growth restriction. Preeclamptic pregnancies delivering after 34 weeks of gestation and IUGR with abnormal values of flow rate in the umbilical artery demonstrated up-regulation of miR-1-3b. Preeclampsia and IUGR requiring termination of gestation before 34 weeks of gestation were associated with down-regulation of miR-26a-5p, miR-103a-3p and miR-145-5p. On the other hand, some of microRNAs (miR-16-5p, miR-100-5p, miR-122-5p, miR-125b-5p, miR-126-3p, miR-143-3p, miR-195-5p, miR-199a-5p, miR-221-3p, miR-342-3p, and miR-574-3p) were only down-regulated or showed a trend to down-regulation just in intrauterine growth restriction pregnancies requiring the delivery before 34 weeks of gestation.

Conclusion

Epigenetic changes induced by pregnancy-related complications in placental tissue may cause later onset of cardiovascular and cerebrovascular diseases in offspring.

MicroRNA-26a inhibits TGF-β-induced extracellular matrix protein expression in podocytes by targeting CTGF and is downregulated in diabetic nephropathy

AIMS/HYPOTHESIS

The accumulation of extracellular matrix (ECM) is a characteristic of diabetic nephropathy, and is partially caused by profibrotic proteins TGF-β and connective tissue growth factor (CTGF). We aimed to identify microRNAs (miRNAs) targeting CTGF on podocytes in diabetic nephropathy.

METHODS

We investigated miRNAs targeting CTGF on podocytes with miRNA array analysis and identified a candidate miRNA, miR-26a. Using overexpression and silencing of miR-26a in cultured podocytes, we examined changes of ECM and its host genes. We further investigated glomerular miR-26a expression in humans and in mouse models of diabetic nephropathy.

RESULTS

miR-26a, which was downregulated by TGF-β1, was expressed in glomerular cells including podocytes and in tubules by in situ hybridisation. Glomerular miR-26a expression was downregulated by 70% in streptozotocin-induced diabetic mice. Transfection of miR-26a mimics in cultured human podocytes decreased the CTGF protein level by 50%, and directly inhibited CTGF expression in podocytes, as demonstrated by a reporter assay with the 3'-untranslated region of the CTGF gene. This effect was abolished by a mutant plasmid. miR-26a mimics also inhibited TGF-β1-induced collagen expression, SMAD-binding activity and expression of its host genes CTDSP2 and CTDSPL. Knockdown of CTDSP2 and CTDSPL increased collagen expression in TGF-β-stimulated podocytes, suggesting that host genes also regulate TGF-β/SMAD signalling. Finally, we observed a positive correlation between microdissected glomerular miR-26a expression levels and estimated GFR in patients with diabetic nephropathy.

CONCLUSIONS/INTERPRETATION

The downregulation of miR-26a is involved in the progression of diabetic nephropathy both in humans and in mice through enhanced TGF-β/CTGF signalling.

High glucose enhances microRNA-26a to activate mTORC1 for mesangial cell hypertrophy and matrix protein expression

High glucose milieu inhibits PTEN expression to activate Akt kinase and induces glomerular mesangial cell hypertrophy and matrix protein expression in diabetic nephropathy. Specific mechanism by which high glucose inhibits PTEN expression is not clear. We found that high glucose increased the expression of the microRNA-26a (miR-26a) in mesangial cells. Using a sensor plasmid with 3'UTR-driven luciferase, we showed PTEN as a target of miR-26a in response to high glucose. Overexpression of miR-26a reduced the PTEN protein levels resulting in increased Akt kinase activity similar to high glucose treatment. In contrast, anti-miR-26a reversed high glucose-induced suppression of PTEN with concomitant inhibition of Akt kinase activity. Akt-mediated phosphorylation of tuberin and PRAS40 regulates mTORC1, which is necessary for mesangial cell hypertrophy and matrix protein expression. Inhibition of high glucose-induced miR-26a blocked phosphorylation of tuberin and PRAS40, which lead to suppression of phosphorylation of S6 kinase and 4EBP-1, two substrates of mTORC1. Furthermore, we show that expression of miR-26a induced mesangial cell hypertrophy and increased fibronectin and collagen I (α2) expression similar to that observed with the cells incubated with high glucose. Anti-miR-26a inhibited these phenomena in response to high glucose. Together our results provide the first evidence for the involvement of miR-26a in high glucose-induced mesangial cell hypertrophy and matrix protein expression. These data indicate the potential therapeutic utility of anti-miR-26a for the complications of diabetic kidney disease.

Reciprocal inhibition between miR-26a and NF-κB regulates obesity-related chronic inflammation in chondrocytes

miR-26a suppresses proinflammatory cytokine production via inactivating NF-κB, whereas NF-κB inhibits miR-26a production through binding to miR-26a promoter. We identified a reciprocal inhibition between miR-26a and NF-κB in obesity-related chondrocytes, providing a potential mechanism linking obesity to osteoarthritis.

Obesity is causally linked to osteoarthritis (OA), with the mechanism being not fully elucidated. miRNAs (miRs) are pivotal regulators of various diseases in multiple tissues, including inflammation in the chondrocytes. In the present study, we for the first time identified the expression of miR-26a in mouse chondrocytes. Decreased level of miR-26a was correlated to increased chronic inflammation in the chondrocytes and circulation in obese mouse model. Mechanistically, we demonstrated that miR-26a attenuated saturated free fatty acid-induced activation of NF-κB (p65) and production of proinflammatory cytokines in chondrocytes. Meanwhile, NF-κB (p65) also suppressed miR-26a production by directly binding to a predicted NF-κB binding element in the promoter region of miR-26a. Finally, we observed a negative correlation between NF-κB and miR-26a in human patients with osteoarthritis. Thus, we identified a reciprocal inhibition between miR-26a and NF-κB downstream of non-esterified fatty acid (NEFA) signalling in obesity-related chondrocytes. Our findings provide a potential mechanism linking obesity to cartilage inflammation.

Psoralen derivatives as inhibitors of NF-κB interaction: the critical role of the furan ring

Simplified analogues of previously reported NF-κB interaction inhibitors, lacking the furan moiety, were synthesized and evaluated by performing experiments based on electrophoretic mobility shift assay (EMSA). The synthetic modifications led to simpler coumarin derivatives with lower activity allowing to better understand the minimal structural requirement for the binding to NF-κB.

MicroRNA-26a regulates RANKL-induced osteoclast formation

Osteoclasts are unique cells responsible for the resorption of bone matrix. MicroRNAs (miRNAs) are involved in the regulation of a wide range of physiological processes. Here, we examined the role of miR-26a in RANKL-induced osteoclastogenesis. The expression of miR-26a was up-regulated by RANKL at the late stage of osteoclastogenesis. Ectopic expression of an miR-26a mimic in osteoclast precursor cells attenuated osteoclast formation, actin-ring formation, and bone resorption by suppressing the expression of connective tissue growth factor/CCN family 2 (CTGF/CCN2), which can promote osteoclast formation via up-regulation of dendritic cell-specific transmembrane protein (DC-STAMP). On the other hand, overexpression of miR-26a inhibitor enhanced RANKL-induced osteoclast formation and function as well as CTGF expression. In addition, the inhibitory effect of miR-26a on osteoclast formation and function was prevented by treatment with recombinant CTGF. Collectively, our results suggest that miR-26a modulates osteoclast formation and function through the regulation of CTGF.

MicroRNA regulatory networks in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, and fatal scarring lung disease of unknown etiology, characterized by changes in microRNA expression. Activation of transforming growth factor (TGF-β) is a key event in the development of IPF. Recent reports have also identified epigenetic modification as an important player in the pathogenesis of IPF. In this review, we summarize the main results of studies that address the role of microRNAs in IPF and highlight the synergistic actions of these microRNAs in regulating TGF-β, the primary fibrogenic mediator. We outline epigenetic regulation of microRNAs by methylation. Functional studies identify microRNAs that alter proliferative and migratory properties of fibroblasts, and induce phenotypic changes in epithelial cells consistent with epithelial-mesenchymal transition. Though these studies were performed in isolation, we identify multiple co-operative actions after assembling the results into a network. Construction of such networks will help identify disease-propelling hubs that can be targeted for therapeutic purposes.