MicroRNA-101 suppresses liver fibrosis by targeting the TGFβ signalling pathway

The role of noncoding RNAs in regulating epithelial responses in COPD

Chronic obstructive pulmonary disease (COPD), one of the leading causes of death in the world, is a chronic inflammatory disease of the airways usually caused by long-term exposure to inhaled irritants. Airway epithelial cells (AECs) play a key role in initializing COPD and driving the exacerbation of this disease through the release of various cytokines. This AEC-derived cytokine response is tightly regulated possibly through the regulatory effects of noncoding RNAs (ncRNAs). Although the importance of ncRNAs in pulmonary diseases has been increasingly realized, little is known about the role of ncRNA in the regulation of inflammatory responses in COPD. This review outlines the features of AEC-derived cytokine responses in COPD and how ncRNAs regulate these inflammatory responses.

Effect of miR-182 on hepatic fibrosis induced by Schistosomiasis japonica by targeting FOXO1 through PI3K/AKT signaling pathway

The study aimed to investigate the impact of miR-182 and FOXO1 on S. japonica-induced hepatic fibrosis. Microarray analysis was performed to screen out differential expressed miRNAs and mRNAs. Rat hepatic fibrosis model and human hepatocellular cell line LX-2 were used to study the effect of miR-182 and FOXO1. qRT-PCR and Western blot were used to detect the expression of miR-182, FOXO1 or other fibrosis markers. The targeting relationship between FOXO1 and miR-182 was verified by luciferase reporter assay. Immunohistochemistry or immunofluorescence staining was conducted to detect FOXO1 or α-SMA in rat hepatic tissues. Cell viability and apoptosis were detected by MTT assay and flow cytometry. The expression of PI3K/AKT pathway-related proteins was detected by Western blot. miR-182 was highly expressed in liver fibrosis samples, and FOXO1 expression was negatively correlated with miR-182 expression. After transfection of miR-182, FOXO1 expression was down-regulated, with the results of LX-2 cells proliferation inhibition and apoptosis induction, as well as the aggravation of rat hepatic fibrosis. The expression of p-AKT/AKT and p-S6/S6 was increased, meaning that the PI3K/AKT signal pathway was activated. The results were reversed when treated with Wortmannin (PI3K inhibitor). After transfection of miR-182 inhibitor, FOXO1 expression was up-regulated, LX-2 cell proliferation was inhibited, and apoptosis rate was increased. High-expressed miR-182 and low-expressed FOXO1 promoted proliferation and inhibiting apoptosis on liver fibrosis cells, stimulating the development of S. japonica-induced hepatic fibrosis through feeding back to PI3K/AKT signaling pathway.

Molecular Pathogenesis of Chlamydia Disease Complications: Epithelial-Mesenchymal Transition and Fibrosis

The reproductive system complications of genital chlamydial infection include fallopian tube fibrosis and tubal factor infertility. However, the molecular pathogenesis of these complications remains poorly understood. The induction of pathogenic epithelial-mesenchymal transition (EMT) through microRNA (miRNA) dysregulation was recently proposed as the pathogenic basis of chlamydial complications. Focusing on fibrogenesis, we investigated the hypothesis that chlamydia-induced fibrosis is caused by EMT-driven generation of myofibroblasts, the effector cells of fibrosis that produce excessive extracellular matrix (ECM) proteins. The results revealed that the targets of a major category of altered miRNAs during chlamydial infection are key components of the pathophysiological process of fibrogenesis; these target molecules include collagen types I, III, and IV, transforming growth factor β (TGF-β), TGF-β receptor 1 (TGF-βR1), connective tissue growth factor (CTGF), E-cadherin, SRY-box 7 (SOX7), and NFAT (nuclear factor of activated T cells) kinase dual-specificity tyrosine (Y) phosphorylation-regulated kinase 1a (Dyrk1a). Chlamydial induction of EMT resulted in the generation of α-smooth muscle actin (α-SMA)-positive myofibroblasts that produced ECM proteins, including collagen types I and III and fibronectin. Furthermore, the inhibition of EMT prevented the generation of myofibroblasts and production of ECM proteins during chlamydial infection. These findings may provide useful avenues for targeting EMT or specific components of the EMT pathways as a therapeutic intervention strategy to prevent chlamydia-related complications.

Intrahepatic MicroRNA Profile of Liver Transplant Recipients with Hepatitis C Virus Co-Infected with Human Immunodeficiency Virus

BACKGROUND In patients with human immunodeficiency virus (HIV) and hepatitis C virus (HCV) co-infection, HIV can modulate HCV replication and immune response as well as accelerate liver fibrosis. The role of miRNA in HIV/HCV co-infection is not fully elucidated. The aim of this study was to examine the differential expression of miRNAs in the liver. MATERIAL AND METHODS Thirteen patients who had undergone a liver transplant (7 HCV-infected and 6 HIV/HCV-co-infected patients) were examined using a miRNA array containing 1347 human miRNAs. To confirm the microarray results, data for 20 patients (10 HCV-infected and 10 HIV/HCV-co-infected) were validated using real-time polymerase chain reaction probing for miR101b, miR149, and miR200c. This miRNA was selected based on microarray results and its biological significance in liver fibrosis. RESULTS Microarray analysis revealed 22 miRNAs that were differentially expressed in the HIV/HCV-co-infected group compared to the HCV-infected group (p<0.05). The expression of miR-101b and miR149 was significantly decreased in the HIV/HCV-co-infected group compared to that in the HCV-infected group (miR101b, 0.103±0.09 vs. 0.0157±0.0093, p=0.007; miR149, 0.152±0.159 vs. 0.0192±0.015, p=0.025). CONCLUSIONS HIV/HCV co-infection may promote liver fibrosis by modulating miRNA expression.

miR-185 Inhibits Fibrogenic Activation of Hepatic Stellate Cells and Prevents Liver Fibrosis

Recent studies have shown the effect of microRNAs on HSC activation and transformation, which is essential for the pathogenesis of liver fibrosis. In our study, we explored the role of miR-185 in liver fibrosis. Plasma miR-185 was detected in hepatitis B virus-related liver fibrosis patients (S2/3, n = 10) by Illumina HiSeq sequencing, and healthy volunteers were selected (n = 8) as the control group. We found that the plasma miR-185 level in fibrosis patients was significantly downregulated. CCl₄-induced fibrosis tissues in mouse livers and TGF-β1-activated HSCs also presented downregulated miR-185 concomitant with an increased expression of RHEB and RICTOR. To explore the correlations, LX-2 cells were transiently transfected with miR-185 mimics. The expression levels of α-SMA, collagen I, and collagen III were decreased as well as RHEB and RICTOR. Inhibition of endogenous miR-185 increased fibrogenic activity. Furthermore, dual-luciferase reporter assays indicated that miR-185 inhibited the expression of RHEB and RICTOR by directly targeting their 3' UTRs. Moreover, silencing RHEB and RICTOR suppressed α-SMA and collagen expression levels. In conclusion, miR-185 prevents liver fibrogenesis by inhibiting HSC activation via inhibition of RHEB and RICTOR. These results provide new insights into the mechanisms behind the anti-fibrotic effect of miR-185.

MiR-142-3p blocks TGF-β-induced activation of hepatic stellate cells through targeting TGFβRI

AIM

To understand the contribution of miR-142-3p in the activation of hepatic stellate cells (HSCs) and liver fibrosis, and the underlying mechanism.

MATERIALS AND METHODS

We detected microRNAs expression profiles in quiescent and activated HSCs by microRNA-array, and performed qRT-PCR to validate these data in HSCs and plasma of cirrhosis patients. In vitro, the 3rd-5th passage HSCs was transfected with mir-142-3p mimics or stimulated with TGF β. The markers of HSCs activation (i.e. FN and α-SMA) were examined by qRT-PCR and western blotting, and cell viability was detected by MTT, colony formation assays respectively.

KEY FINDING

In our study, we identified miR-142-3p as a novel regulator of HSCs activation and indicator of hepatic cirrhosis. We found that miR-142-3p was significantly reduced in activated HSCs, while TGFβRI was distinctly up-regulated in activated HSCs. Ectopic expression of miR-142-3p in activated HSCs inhibited cell viability as well as cell growth, and blocked HSCs activation, concomitant with decreased transdifferentiation markers (i.e. FN and α-SMA). Further, we confirmed that miR-142-3p was reduced upon TGF-β exposure, while diminishing TGF-β-Smad signaling pathway in turn by reducing TGFβRI expression in HSCs. Besides, the plasma level of miR-142-3p declined significantly in patients with hepatic cirrhosis.

SIGNIFICANCE

In conclusion, we demonstrated that miR-142-3p repressed TGF-β-Smad signaling pathway to prevent HSCs activation through directly targeting TGFβRI in HSCs.

Lentivirus-mediated over-expression of let-7b microRNA suppresses hepatic fibrosis in the mouse infected with Schistosoma japonicum

Transforming growth factor-β (TGF-β) signaling pathway is documented to participate in liver fibrosis via multifactorial mechanisms. microRNA Let-7b (Let-7b) has been proved to alleviate cell fibrosis through regulating TGF-β receptor I (TβRI), but whether it is involved in Schistosomiasis liver fibrosis (SLF) has not been determined. In the present, SLF mice model was used to investigate Let-7b's function and mechanism in SLF. We found that hepatic let-7b expression was continuously declined in SLF, accompanied by the induction of TGF-β pathway molecules (TGF-β1, TβRI), profibrogenic mediators (α-SMA, colla I), and Th1/Th2 cells response factors (IFN-γ, IL-4). When recombinant Lentivirus of let-7b (Lenti-let-7b) was transfected into S. japonicum-infected mice, the mice hepatic fibrosis was distinctly ameliorated, and TGF-β1, TβRI, α-SMA, and colla I expressions were remarkly decreased, mice serum IL-4 and IFN-γ levels were reduced. Similarly, over-expression of let-7b down-regulated the expression of TβRI in THP-1 cells transfected with let-7b mimics, while TβRI was up-regulated after treated with let-7b inhibitor. These findings suggested that let-7b is a negative regulator to SLF through downregulating TβRI, and inhibits Th1 and Th2 type cell immune response. This provides a novel potential therapeutic strategy for SFL prevention.

NEAT1 accelerates the progression of liver fibrosis via regulation of microRNA-122 and Kruppel-like factor 6

Long non-coding RNAs (lncRNAs) have been reported to be involved in many important biological processes including proliferation, apoptosis, differentiation, and survival. Recently, nuclear paraspeckle assembly transcript 1 (NEAT1), a novel lncRNA, serves as a crucial regulator in tumors. However, the biological role of NEAT1 in liver fibrosis is largely unknown. In this study, the role of NEAT1 was explored in primary mouse hepatic stellate cells (HSCs) and carbon tetrachloride (CCl₄)-induced mouse liver fibrosis models. We found that NEAT1 expression was significantly increased in CCl₄-induced mice and activated HSCs. Loss of NEAT1 suppressed liver fibrosis in vivo and in vitro. Conversely, NEAT1 overexpression accelerated HSC activation, including increased cell proliferation and collagen expression. Further studies indicated that the microRNA-122 (miR-122)-Kruppel-like factor 6 (KLF6) axis was involved in the effects of NEAT1 on HSC activation. The effects of NEAT1 on HSC activation were almost blocked down by miR-122 mimics or KLF6 knockdown. Interestingly, both NEAT1 and KLF6 are targets of miR-122. In addition, miR-122 led to a significant reduction in NEAT1 level while NEAT1 overexpression resulted in the suppression of miR-122 expression. Pull-down assay confirmed a direct interaction between miR-122 and NEAT1. NEAT1 contributes to HSC activation via the miR-122-KLF6 axis. In human fibrotic liver samples, increased NEAT1 levels positively correlated with liver fibrosis markers. In conclusion, we disclose a novel NEAT1-miR-122-KLF6 signaling cascade and its implication in liver fibrosis.

KEY MESSAGES

NEAT1 was significantly increased in CCl₄-induced mice and activated HSCs. Loss of NEAT1 suppressed liver fibrosis in vivo and in vitro. KLF6 and miR-122 were required for the effects of NEAT1 on HSC activation. NEAT1 contributes to HSC activation via competitively binding miR-122. We disclose a novel NEAT1-miR-122-KLF6 signaling cascade.

Bioinformatic analysis of microRNA-mRNA expression profiles of bladder tissue induced by bladder outlet obstruction in a rat model

Various microRNAs (miRNAs) have previously been demonstrated to exhibit an association with the process of bladder remodeling, induced by bladder outlet obstruction (BOO). However, little is known about miRNA and gene expression profiles and the molecular mechanism underlying bladder pathophysiological alterations. The present study used bioinformatic analysis technology to examine the altered miRNA and mRNA expression profiles of bladder tissue in a rat model of BOO and validate the involved signaling pathways. The gene expression profile data was downloaded from Gene Expression Omnibus (GEO), and the differentially expressed genes (DEGs) and differentially expressed miRNAs (DEMs) were screened. Potential target genes of DEMs were predicted. The target genes and DEGs were used for further gene ontology (GO) analysis followed by Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis using the Database for Annotation, Visualization and Integrated Discovery. The present study additionally constructed a DEM‑DEG interaction network. A total of 9 DEMs (3 upregulated and 6 downregulated) were identified; 664 DEGs were screened. KEGG analysis revealed that the DEGs were involved in the regulation of the actin cytoske-leton, extracellular matrix (ECM) remodeling, cell adhesion and the cell cycle. Additionally, KEGG classification indicated that these genes were important in angiogenesis, and in the p53 and transforming growth factor‑β signaling pathways. Notably, rno‑miRNA (miR)‑26b and rno‑miR‑101b were the two larger nodes of the 7 obstruction‑associated DEMs and interacted with 32 and 27 DEGs, respectively. On removal of obstruction, few DEMs were present; however, 370 genes exhibited the opposite expression trend. The majority of pathways enriched for the DEGs were identified and were associated with ECM‑receptor interaction and focal adhesion. In the DEM‑DEG regulatory network, miR‑495, miR‑494 and their target genes were significantly differentially expressed. The present study demonstrated that miRNAs and genes may be potential biomarkers of bladder remodeling induced by BOO, and additionally provided novel insights into the molecular mechanisms underlying this disorder.

MicroRNA-146a-5p attenuates liver fibrosis by suppressing profibrogenic effects of TGFβ1 and lipopolysaccharide

Liver fibrosis is characterized by proliferation and activation of hepatic stellate cells (HSCs). Transforming growth factor-β1 (TGFβ1) is crucial for liver fibrogenesis, and gut-derived endotoxin (LPS) also plays an important role in liver fibrogenesis. In the present study, we found that microRNA-146a-5p (miR-146a-5p) could regulate TGFβ1/Smad and LPS/NF-κB/Bambi pathways to attenuate liver fibrosis. Downregulated miR-146a-5p and upregulated level of LPS were found in liver of CCl4-treated rats. On cellular level, expression of miR-146a-5p is reduced during primary rat HSCs naturally activation and changed in response to TGFβ1 and/or LPS stimulation in primary rat HSCs and human HSC line LX-2. Further overexpression of miR-146a-5p suppresses proliferation and activation of HSCs. The underlying mechanism involved that miR-146a-5p directly suppresses profibrogenic effects of TGFβ1 by down-regulating the expression of Smad4 and phosphorylation of Smad2. Moreover, miR-146a-5p indirectly suppresses TGFβ1/Smad pathway by targeting IL-1 receptor-associated kinase 1 (IRAK1) and TNF receptor associated factor-6 (TRAF6), two major components of LPS/NF-κB/Bambi pathway, to reduce inhibition of TGFβ pseudoreceptor Bambi. These results indicate that miR-146a-5p abrogate hepatic fibrosis by suppressing both TGFβ/Smad and LPS/NF-κB/Bambi signaling pathway in HSCs and suggest that miR-146a-5p is a potential therapeutic target for liver fibrosis.

MicroRNA-101 attenuates pulmonary fibrosis by inhibiting fibroblast proliferation and activation

Aberrant proliferation and activation of lung fibroblasts contribute to the initiation and progression of idiopathic pulmonary fibrosis (IPF). However, the mechanisms responsible for the proliferation and activation of fibroblasts are not fully understood. The objective of this study was to investigate the role of miR-101 in the proliferation and activation of lung fibroblasts. miR-101 expression was determined in lung tissues from patients with IPF and mice with bleomycin-induced pulmonary fibrosis. The regulation of miR-101 and cellular signaling was investigated in pulmonary fibroblasts in vitro The role of miR-101 in pulmonary fibrosis in vivo was studied using adenovirus-mediated gene transfer in mice. The expression of miR-101 was down-regulated in fibrotic lungs from patients with IPF and bleomycin-treated mice. The down-regulation of miR-101 occurred via the E26 transformation-specific (ETS) transcription factor. miR-101 suppressed the WNT5a-induced proliferation of lung fibroblasts by inhibiting NFATc2 signaling via targeting Frizzled receptor 4/6 and the TGF-β-induced activation of lung fibroblasts by inhibition of SMAD2/3 signaling via targeting the TGF-β receptor 1. Adenovirus-mediated miR-101 gene transfer in the mouse lung attenuated bleomycin-induced lung fibrosis and improved lung function. Our data suggest that miR-101 is an anti-fibrotic microRNA and a potential therapeutic target for pulmonary fibrosis.

DNA Methyltransferases Modulate Hepatogenic Lineage Plasticity of Mesenchymal Stromal Cells

The irreversibility of developmental processes in mammalian cells has been challenged by rising evidence that de-differentiation of hepatocytes occurs in adult liver. However, whether reversibility exists in mesenchymal stromal cell (MSC)-derived hepatocytes (dHeps) remains elusive. In this study, we find that hepatogenic differentiation (HD) of MSCs is a reversible process and is modulated by DNA methyltransferases (DNMTs). DNMTs are regulated by transforming growth factor β1 (TGFβ1), which in turn controls hepatogenic differentiation and de-differentiation. In addition, a stepwise reduction in TGFβ1 concentrations in culture media increases DNMT1 and decreases DNMT3 in primary hepatocytes (Heps) and confers Heps with multi-differentiation potentials similarly to MSCs. Hepatic lineage reversibility of MSCs and lineage conversion of Heps are regulated by DNMTs in response to TGFβ1. This previously unrecognized TGFβ1-DNMTs-MSC-HD axis may further increase the understanding the normal and pathological processes in the liver, as well as functions of MSCs after transplantation to treat liver diseases.

TGF-β-induced hepatocyte lincRNA-p21 contributes to liver fibrosis in mice

Hepatocyte death, as well as the following inflammatory and fibrogenic signaling cascades, is the key trigger of liver fibrosis. Here, we isolated hepatocytes from CCl₄-induced fibrotic liver and found that hepatocyte lincRNA-p21 significantly increased during liver fibrosis. The increase of hepatocyte lincRNA-p21 was associated with the loss of miR-30, which can inhibit TGF-β signaling by targeting KLF11. We revealed that lincRNA-p21 modulated miR-30 availability by acting as a competing endogenous RNA (ceRNA). The physiological significance of this interaction is highlighted by the feedback loop, in which lincRNA-p21 works as a downstream effector of the TGF-β signaling to strengthen TGF-β signaling and mediate its role in promoting liver fibrosis by interacting with miR-30. In vivo results showed that knockdown of hepatocyte lincRNA-p21 greatly reduced CCl₄-induced liver fibrosis and inflammation, whereas ectopic expression of miR-30 in hepatocyte exhibited the similar results. Mechanistic studies further revealed that inhibition of miR-30 impaired the effects of lincRNA-p21 on liver fibrosis. Additionally, lincRNA-p21 promoted hepatocyte apoptosis in vitro and in vivo, whereas the proliferation rate of hepatocyte was suppressed by lincRNA-p21. The pleiotropic roles of hepatocyte lincRNA-p21 suggest that it may represent an unknown paradigm in liver fibrosis and serve as a potential target for therapy.

Dysregulation of miRNA Expression in Cancer Associated Fibroblasts (CAFs) and Its Consequences on the Tumor Microenvironment

The tumor microenvironment, including cancer-associated fibroblasts (CAF), has developed as an important target for understanding tumor progression, clinical prognosis and treatment responses of cancer. Cancer cells appear to transform normal fibroblasts (NF) into CAFs involving direct cell-cell communication and epigenetic regulations. This review summarizes the current understanding on miR involvement in cancer cell—tumor environment/stroma communication, transformation of NFs into CAFs, their involved targets and signaling pathways in these interactions; and clinical relevance of CAF-related miR expression profiles. There is evidence that miRs have very similar roles in activating hepatic (HSC) and pancreatic stellate cells (PSC) as part of precancerous fibrotic diseases. In summary, deregulated miRs affect various intracellular functional complexes, such as transcriptional factors, extracellular matrix, cytoskeleton, EMT/MET regulation, soluble factors, tyrosine kinase and G-protein signaling, apoptosis and cell cycle & differentiation, but also formation and composition of the extracellular microenvironment. These processes result in the clinical appearance of desmoplasia involving CAFs and fibrosis characterized by deregulated stellate cells. In addition, modulated release of soluble factors can act as (auto)activating feedback loop for transition of NFs into their pathological counterparts. Furthermore, epigenetic communication between CAFs and cancer cells may confer to cancer specific functional readouts and transition of NF. MiR related epigenetic regulation with many similarities should be considered as key factor in development of cancer and fibrosis specific environment.

MiR-130a-3p attenuates activation and induces apoptosis of hepatic stellate cells in nonalcoholic fibrosing steatohepatitis by directly targeting TGFBR1 and TGFBR2

Nonalcoholic fibrosing steatohepatitis is a uniform process that occurs throughout nonalcoholic fatty liver disease (NAFLD). MicroRNAs (miRNAs) have been shown to be involved in the biological processes, but the role and molecular mechanism of miRNAs in NAFLD are not entirely clear. In this study, we observed a significant reduction in the expression of miR-130a-3p in livers of a mouse model with fibrosis induced by a methionine–choline-deficient diet, of NAFLD patients, and in activated hepatic stellate cells (HSCs). A dual-luciferase activity assay confirmed that transforming growth factor-beta receptors (TGFBRs) 1 and 2 were both the target genes of miR-130a-3p. The hepatic expression of TGFBR1 and TGFBR2 was significantly increased. Moreover, the overexpression of miR-130a-3p in HSCs inhibited HSC activation and proliferation, concomitant with the decreased expression of TGFBR1, TGFBR2, Smad2, Smad3, matrix metalloproteinase-2 (MMP-2), MMP-9, type I collagen (Col-1), and Col-4. In addition, the overexpression of miR-130a-3p promoted HSC apoptosis by inducing the expression of caspase-dependent apoptosis genes. Transfection with si-TGFBR1 and si-TGFBR2 revealed effects on HSC function that were consistent with those of miR-130a-3p. TGFBR1 and TGFBR2 rescued the miR-130a-3p-mediated reductions in the mRNA and protein expression levels of Smad2, Smad3, Col-1, and Col-4. In conclusion, our findings suggest that miR-130a-3p might play a critical role in negatively regulating HSC activation and proliferation in the progression of nonalcoholic fibrosing steatohepatitis by directly targeting TGFBR1 and TGFBR2 via the TGF-β/SMAD signaling pathway.

Knockdown of miR-23, miR-27, and miR-24 Alters Fetal Liver Development and Blocks Fibrosis in Mice

MicroRNAs (miRNAs) regulate cell fate selection and cellular differentiation. miRNAs of the miR23b polycistron (miR-23b, miR-27b, and miR-24) target components of the TGF-β signaling pathway and affect murine bile ductular and hepatocyte cell fate selection in vitro. Here we show that miR-23b polycistron miRNAs directly target murine Smad4, which is required for TGF-β signaling. Injection of antagomirs against these miRNAs directly into E16.5 murine fetuses caused increased cytokeratin expression in sinusoids and primitive ductular elements throughout the parenchyma of newborn mice. Similar antagomir injection in newborn mice increased bile ductular differentiation in the liver periphery and reduced hepatocyte proliferation. Antagomir injection in newborn Alb/TGF-β1 transgenic mice that develop fibrosis inhibited the development of fibrosis, and injection of older mice caused the resolution of existing fibrosis. Furthermore, murine stellate cell activation, including ColA1 and ACTA2 expression, is regulated by miR-23b cluster miRNAs. In summary, knockdown of miR-23b cluster miRNAs in fetal and newborn liver promotes bile duct differentiation and can block or revert TGF-β-induced liver fibrosis that is dependent on stellate cell activation. These data may find practical application in the highly needed development of therapies for the treatment of fibrosis.

MicroRNAs regulate hepatic fibrosis via TGF-β/Smad pathway

Studies have shown that transforming growth factor-β (TGF-β) is one of the most important factors to promote hepatic fibrosis (HF), and the TGF-β/Smad pathway is a major signaling pathway involved in HF. Abnormal expression of microRNAs (miRNAs) has a key role in the development of HF. In recent years, studies suggest that regulating miRNAs may affect the TGF-β/Smad pathway. This paper discusses the TGF-β/Smad pathway and the related miRNAs that are associated with HF.

Latest advances in understanding of relationship between microRNAs and hepatic fibrosis

Studies have shown the expression of microRNAs (miRNAs) in hepatic fibrosis. MiRNAs are important in regulating hepatic fibrosis, and have a close relationship with the occurrence, development, diagnosis and treatment of hepatic fibrosis. This article reviews the latest advances in the understanding of the relationship between miRNAs and hepatic fibrosis.

MicroRNAs-mediated epithelial-mesenchymal transition in fibrotic diseases

MicroRNAs (miRNAs), a large family of small and highly conserved non-coding RNAs, regulate gene expression through translational repression or mRNA degradation. Aberrant expression of miRNAs underlies a spectrum of diseases including organ fibrosis. Recent evidence suggests that miRNAs contribute to organ fibrosis through mediating epithelial-mesenchymal transition (EMT). Alleviation of EMT has been proposed as a promising strategy against fibrotic diseases given the key role of EMT in fibrosis. miRNAs impact the expression of specific ligands, receptors, and signaling pathways, thus modulating EMT and consequently influencing fibrosis. This review summarizes the current knowledge concerning how miRNAs regulate EMT and highlights the specific roles that miRNAs-regulated EMT plays in fibrotic diseases as diverse as pulmonary fibrosis, hepatic fibrosis, renal fibrosis and cardiac fibrosis. It is desirable that a more comprehensive understanding of the functions of miRNAs-regulated EMT will facilitate the development of novel diagnostic and therapeutic strategies for various debilitating organ fibrosis.

Comparative analysis of hepatic miRNA levels in male marathon mice reveals a link between obesity and endurance exercise capacities

Dummerstorf marathon mice (DUhTP) are characterized by increased accretion of peripheral body fat with fast mobilization in response to mild physical activity if running wheels were included in their home cages. The obese phenotype coincides with elevated hepatic lipogenesis if compared to unselected controls. We now asked, if microRNA (miRNA) species present in the liver may contribute to the obese phenotype of DUhTP mice and if miRNAs respond to mild physical activity in our mouse model. Total RNA was extracted from livers of sedentary or physically active marathon mice and controls and analyzed by array hybridization or real-time PCR using locked nucleic acid probes. Pathway analysis of altered miRNA concentrations identified fatty acid biosynthesis as the most important target for the effects of miRNAs in the liver. A miRNA signature consisting of miR-21, 27, 33, 122, and 143 was present at higher abundance (p < 0.01) in the liver of sedentary or active DUhTP mice indicating involvement of miRNAs with hepatic lipogenesis. Furthermore, in protein lysates from the liver of DUhTP mice, significantly reduced concentrations of total and phosphorylated AKT and lower levels of phosphorylated AMPK were found (p < 0.05). Our results indicate active involvement of miRNAs in the control of hepatic energy metabolism and discuss effects on signal transduction as a potentially direct effect of miR-143 in the liver of DUhTP mice.

miR-706 inhibits the oxidative stress-induced activation of PKCα/TAOK1 in liver fibrogenesis

Oxidative stress induces the activation of liver fibrogenic cells (myofibroblasts), thus promoting the expression of fibrosis-related genes, leading to hepatic fibrogenesis. MicroRNAs (miRNAs) are a new class of small RNAs ~18–25 nucleotides in length involved in post-transcriptional regulation of gene expression. Wound-healing and remodeling processes in liver fibrosis have been associated with changes in hepatic miRNA expression. However, the role of miR-706 in liver fibrogenesis is currently unknown. In the present study, we show that miR-706 is abundantly expressed in hepatocytes. Moreover, oxidative stress leads to a significant downregulation of miR-706, and the further reintroduction of miR-706 inhibits oxidative stress-induced expression of fibrosis-related markers such as α-SMA. Subsequent studies revealed that miR-706 directly inhibits PKCα and TAOK1 expression via binding to the 3′-untranslated region, preventing epithelial mesenchymal transition. In vivo studies showed that intravenous injection of miR-706 agomir successfully increases hepatic miR-706 and decreases α-SMA, PKCα, and TAOK1 protein levels in livers of carbon tetrachloride (CCl₄)-treated mice. In summary, this study reveals a protective role for miR-706 by blocking the oxidative stress-induced activation of PKCα/TAOK1. Our results further identify a major implication for miR-706 in preventing hepatic fibrogenesis and suggest that miR-706 may be a suitable molecular target for anti-fibrosis therapy.

Diosmin attenuates radiation-induced hepatic fibrosis by boosting PPAR-γ expression and hampering miR-17-5p-activated canonical Wnt-β-catenin signaling

BACKGROUND

Liver fibrosis is one of the major complications from upper right quadrant radiotherapy. MicroRNA-17-5p (miR-17-5p) is hypothesized to act as a regulator of hepatic stellate cell (HSCs) activation by activation of the canonical Wnt-β-catenin pathway. Diosmin (Dios), a citrus bioflavonoid, is known to possess potent antioxidant, anti-inflammatory, and anti-apoptotic properties.

PURPOSE

To explore the molecular mechanisms that underlie radiation-induced liver fibrosis, and to evaluate the possible influence of Dios on the miR-17-5p-Wnt-β-catenin signaling axis during fibrogenesis provoked by irradiation (IRR) in rats. Also, the effect of Dios on hepatic peroxisome proliferator activated receptor-γ (PPAR-γ) expression as a regulator for HSC activation was considered.

METHODS

We administered 100 mg·(kg body mass)^-1·day^-1 (per oral) of Dios were administered to IRR-exposed rats (overall dose of 12 Gy on 6 fractions of 2 Gy each) for 6 successive weeks.

RESULTS

Data analysis revealed that Dios treatment mitigated oxidative stress, enhanced antioxidant defenses, alleviated hepatic inflammatory responses, abrogated pro-fibrogenic cytokines, and stimulated PPAR-γ expression. Dios treatment repressed the miR-17-5p activated Wnt-β-catenin signaling induced by IRR. Moreover, Dios treatment restored the normal hepatic architecture and reversed pathological alterations induced by IRR.

CONCLUSION

We hypothesize that the stimulation of PPAR-γ expression and interference with miR-17-5p activated Wnt-β-catenin signaling mediates the antifibrotic properties of Dios.

MicroRNA-17-5p-activated Wnt/β-catenin pathway contributes to the progression of liver fibrosis

Aberrant Wnt/β-catenin pathway contributes to the development of liver fibrosis. MicroRNAs (MiRNAs) are found to act as regulators of the activation of hepatic stellate cell (HSC) in liver fibrosis. However, whether miRNAs activate Wnt/β-catenin pathway in activated HSCs during liver fibrosis is largely unknown. In this study, we found that Salvianolic acid B (Sal B) treatment significantly inhibited liver fibrosis in CCl₄-treated rats, HSC-T6 cells and rat primary HSCs, resulting in the suppression of type I collagen and alpha-smooth muscle actin. Also, Sal B suppressed HSC activation and cell proliferation in vitro. Interestingly, Sal B treatment induced the inactivation of Wnt/β-catenin pathway, with an increase in P-β-catenin and Wnt inhibitory factor 1 (WIF1). We demonstrated that the anti-fibrotic effects caused by Sal B were, at least in part, via WIF1. Moreover, our study revealed that miR-17-5p was reduced in vivo and in vitro after Sal B treatment. As confirmed by luciferase activity assays, WIF1 was a direct target of miR-17-5p. Notably, the suppression of HSCs induced by Sal B was almost inhibited by miR-17-5p mimics. Collectively, we demonstrated that miR-17-5p activates Wnt/β-catenin pathway to result in HSC activation through inhibiting WIF1 expression.

MALAT1 functions as a competing endogenous RNA to mediate Rac1 expression by sequestering miR-101b in liver fibrosis

Emerging evidence shows that Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) plays a pivotal role in cell proliferation, migration, and invasion in tumors. However, the biological role and underlying mechanism of MALAT1 in liver fibrosis remains undefined. In this study, up-regulation of MALAT1 was observed in fibrotic liver tissues and in activated hepatic stellate cells (HSCs). In addition, depletion of MALAT1 inhibited the activation of HSCs in vitro and attenuated collagen deposits in vivo. Our results demonstrated that MALAT1 expression is negatively correlated with microRNA-101b (miR-101b) expression. Furthermore, there was a negative feedback loop between the levels of MALAT1 and miR-101b. Luciferase reporter assay indicated that MALAT1 and RAS-related C3 botulinum substrate 1 (Rac1) are targets of miR-101b. We uncovered that MALAT1 regulates Rac1 expression through miR-101b as a competing endogenous RNA (ceRNA), thereby influencing the proliferation, cell cycle and activation of primary HSCs. Collectively, The ceRNA regulatory network may prompt a better understanding of liver fibrogenesis and contribute to a novel therapeutic strategy for liver fibrosis.

Identification of a Novel lincRNA-p21-miR-181b-PTEN Signaling Cascade in Liver Fibrosis

Previously, we found that long intergenic noncoding RNA-p21 (lincRNA-p21) inhibits hepatic stellate cell (HSC) activation and liver fibrosis via p21. However, the underlying mechanism of the antifibrotic role of lincRNA-p21 in liver fibrosis remains largely unknown. Here, we found that lincRNA-p21 expression was significantly downregulated during liver fibrosis. In LX-2 cells, the reduction of lincRNA-p21 induced by TGF-β1 was in a dose- and time-dependent manner. lincRNA-p21 expression was reduced in liver tissues from patients with liver cirrhosis when compared with that of healthy controls. Notably, lincRNA-p21 overexpression contributed to the suppression of HSC activation. lincRNA-p21 suppressed HSC proliferation and induced a significant reduction in α-SMA and type I collagen. All these effects induced by lincRNA-p21 were blocked down by the loss of PTEN, suggesting that lincRNA-p21 suppressed HSC activation via PTEN. Further study demonstrated that microRNA-181b (miR-181b) was involved in the effects of lincRNA-p21 on HSC activation. The effects of lincRNA-p21 on PTEN expression and HSC activation were inhibited by miR-181b mimics. We demonstrated that lincRNA-p21 enhanced PTEN expression by competitively binding miR-181b. In conclusion, our results disclose a novel lincRNA-p21-miR-181b-PTEN signaling cascade in liver fibrosis and suggest lincRNA-p21 as a promising molecular target for antifibrosis therapy.

miR-1273g-3p modulates activation and apoptosis of hepatic stellate cells by directly targeting PTEN in HCV-related liver fibrosis

MicroRNA (miRNA) play a pivotal role in the development of liver fibrosis. However, the functions of miRNA in hepatitis C virus (HCV)-related liver fibrosis remain unclear. In this study, we systematically analyzed the microarray data of the serum miRNA in patients with HCV-induced hepatic fibrosis. Among 41 dysregulated miRNA, miR-1273g-3p was the most significantly upregulated miRNA and correlated with the stage of liver fibrosis. Overexpression of miR-1273g-3p could inhibit translation of PTEN, increase the expression of α-SMA, Col1A1, and reduce apoptosis in HSCs. Hence, we conclude that miR-1273g-3p might affect the activation and apoptosis of HSCs by directly targeting PTEN in HCV-related liver fibrosis.

MicroRNAs in liver fibrosis: Focusing on the interaction with hedgehog signaling

Liver fibrosis is a repair process in response to damage in the liver; however, severe and chronic injury promotes the accumulation of fibrous matrix, destroying the normal functions and architecture of liver. Hepatic stellate cells (HSCs) are quiescent in normal livers, but in damaged livers, they transdifferentiate into myofibroblastic HSCs, which produce extracellular matrix proteins. Hedgehog (Hh) signaling orchestrates tissue reconstruction in damaged livers and contributes to liver fibrogenesis by regulating HSC activation. MicroRNAs (miRNAs), endogenous small non-coding RNAs interfering with RNA post-transcriptionally, regulate various cellular processes in healthy organisms. The dysregulation of miRNAs is closely associated with diseases, including liver diseases. Thus, miRNAs are good targets in the diagnosis and treatment of various diseases, including liver fibrosis; however, the regulatory mechanisms of miRNAs that interact with Hh signaling in liver fibrosis remain unclear. We review growing evidence showing the association of miRNAs with Hh signaling. Recent studies suggest that Hh-regulating miRNAs induce inactivation of HSCs, leading to decreased hepatic fibrosis. Although miRNA-delivery systems and further knowledge of interacting miRNAs with Hh signaling need to be improved for the clinical usage of miRNAs, recent findings indicate that the miRNAs regulating Hh signaling are promising therapeutic agents for treating liver fibrosis.

Slug-upregulated miR-221 promotes breast cancer progression through suppressing E-cadherin expression

It is generally regarded that E-cadherin is downregulated during tumorigenesis via Snail/Slug-mediated E-cadherin transcriptional reduction. However, this transcriptional suppressive mechanism cannot explain the failure of producing E-cadherin protein in metastatic breast cancer cells after overexpressing E-cadherin mRNA. Here we reveal a novel mechanism that E-cadherin is post-transcriptionally regulated by Slug-promoted miR-221, which serves as an additional blocker for E-cadherin expression in metastatic tumor cells. Profiling the predicted E-cadherin-targeting miRNAs in breast cancer tissues and cells showed that miR-221 was abundantly expressed in breast tumor and metastatic MDA-MB-231 cells and its level was significantly higher in breast tumor or MDA-MB-231 cells than in distal non-tumor tissue and low-metastatic MCF-7 cells, respectively. MiR-221, which level inversely correlated with E-cadherin level in breast cancer cells, targeted E-cadherin mRNA open reading frame (ORF) and suppressed E-cadherin protein expression. Depleting or increasing miR-221 level in breast cancer cells induced or decreased E-cadherin protein level, leading to suppressing or promoting tumor cell progression, respectively. Moreover, miR-221 was specifically upregulated by Slug but not Snail. TGF-β treatment enhanced Slug activity and thus increased miR-221 level in MCF-7 cells. In summary, our results provide the first evidence that Slug-upregulated miR-221 promotes breast cancer progression via reducing E-cadherin expression.

TGF-β: the master regulator of fibrosis

Transforming growth factor-β (TGF-β) is the primary factor that drives fibrosis in most, if not all, forms of chronic kidney disease (CKD). Inhibition of the TGF-β isoform, TGF-β1, or its downstream signalling pathways substantially limits renal fibrosis in a wide range of disease models whereas overexpression of TGF-β1 induces renal fibrosis. TGF-β1 can induce renal fibrosis via activation of both canonical (Smad-based) and non-canonical (non-Smad-based) signalling pathways, which result in activation of myofibroblasts, excessive production of extracellular matrix (ECM) and inhibition of ECM degradation. The role of Smad proteins in the regulation of fibrosis is complex, with competing profibrotic and antifibrotic actions (including in the regulation of mesenchymal transitioning), and with complex interplay between TGF-β/Smads and other signalling pathways. Studies over the past 5 years have identified additional mechanisms that regulate the action of TGF-β1/Smad signalling in fibrosis, including short and long noncoding RNA molecules and epigenetic modifications of DNA and histone proteins. Although direct targeting of TGF-β1 is unlikely to yield a viable antifibrotic therapy due to the involvement of TGF-β1 in other processes, greater understanding of the various pathways by which TGF-β1 controls fibrosis has identified alternative targets for the development of novel therapeutics to halt this most damaging process in CKD.

MicroRNA-215 Regulates Fibroblast Function: Insights from a Human Fibrotic Disease

MicroRNAs are implicated in the regulation of gene expression via various mechanisms in health and disease, including fibrotic processes. Pterygium is an ocular surface condition characterized by abnormal fibroblast proliferation and matrix deposition. We aimed to investigate the role of microRNAs in pterygium and understand the relevant cellular and molecular mechanisms. To achieve this objective, a combination of approaches using surgically excised paired human pterygium and conjunctival tissues as well as cultured primary fibroblast cells from tissue explants were evaluated. Fibroblast dysfunction has been shown to play a central role in pterygium pathology. Here we show that miR-215, among a few others, was down-regulated (2-fold) in pterygium compared to control, and this was consistent in microarray, real-time PCR and fluorescent in-situ hybridization. The effects of increased miR-215 were investigated by adding exogenous miR-215 to fibroblasts, and this showed a decrease in cell proliferation but no significant apoptosis compared to control. Further cell cycle analysis showed that miR-215 depressed progression of cells at G1/S as well as G2/M. A few cell cycle related transcripts were downregulated (2.2-4.5-fold) on addition of miR-215: Mcm3, Dicer1, Cdc25A, Ick, Trip13 and Mcm10. Theoretic binding energies were used to predict miR-215 binding targets and luciferase reporter studies confirmed Mcm10 and Cdc25A as direct targets. In summary, mir-215 could play a role in inhibiting fibroblast proliferation in ocular surface conjunctiva. Dampening of this mir-215 could result in increased fibroblast cell cycling and proliferation, with possibly increased fibroblastic production of matrix, inducing pterygium formation.

Identification of a novel TGF-β-miR-122-fibronectin 1/serum response factor signaling cascade and its implication in hepatic fibrogenesis

Transforming growth factor-β (TGF-β) is a potent cytokine that promotes the development of fibrogenic cells, stimulates the expression of fibrosis-related genes, and consequently results in hepatic fibrogenesis. The involvement of miRNAs in this process remains largely unknown. We showed that miR-122 was substantially expressed in hepatic stellate cells (HSCs) and fibroblasts, the major sources of fibrogenic cells in liver tissues. Notably, exposure to TGF-β led to significant downregulation of miR-122. Furthermore, reintroduction of miR-122 suppressed TGF-β-induced expression of fibrosis-related genes, including alpha smooth muscle actin (α-SMA), fibronectin 1 (FN1) and α1 type I collagen (COL1A1), in HSCs and fibroblasts. Subsequent mechanism investigations revealed that miR-122 directly inhibited FN1 expression by binding to its 3′-untranslated region and indirectly reduced the transcription of α-SMA and COL1A1 by inhibiting the expression of serum response factor (SRF), a key transcription factor that mediated the activation of fibrogenic cells. Further in vivo studies disclosed that intravenous injection of miR-122-expressing lentivirus successfully increased miR-122 level and reduced the amount of collagen fibrils, FN1 and SRF in the livers of CCl₄-treated mice. These findings disclose a novel TGF-β-miR-122-FN1/SRF signaling cascade and its implication in hepatic fibrogenesis, and suggest miR-122 as a promising molecular target for anti-fibrosis therapy.

MicroRNA-378 limits activation of hepatic stellate cells and liver fibrosis by suppressing Gli3 expression

Hedgehog (Hh) signalling regulates hepatic fibrogenesis. MicroRNAs (miRNAs) mediate various cellular processes; however, their role in liver fibrosis is unclear. Here we investigate regulation of miRNAs in chronically damaged fibrotic liver. MiRNA profiling shows that expression of miR-378 family members (miR-378a-3p, miR-378b and miR-378d) declines in carbon tetrachloride (CCl₄)-treated compared with corn-oil-treated mice. Overexpression of miR-378a-3p, directly targeting Gli3 in activated hepatic stellate cells (HSCs), reduces expression of Gli3 and profibrotic genes but induces gfap, the inactivation marker of HSCs, in CCl₄-treated liver. Smo blocks transcriptional expression of miR-378a-3p by activating the p65 subunit of nuclear factor-κB (NF-κB). The hepatic level of miR-378a-3p is inversely correlated with the expression of Gli3 in tumour and non-tumour tissues in human hepatocellular carcinoma. Our results demonstrate that miR-378a-3p suppresses activation of HSCs by targeting Gli3 and its expression is regulated by Smo-dependent NF-κB signalling, suggesting miR-378a-3p has therapeutic potential for liver fibrosis.

Liver fibrosis is a pathogenic driver of many liver diseases, so understanding its regulation might open the door to new therapies. Here the authors perform a screen for miRNA candidates and identify that miR-378 inhibits liver fibrosis in mice by interfering with Hedgehog signalling in hepatic stellate cells.

Hepatic Stellate Cells and microRNAs in Pathogenesis of Liver Fibrosis

microRNAs (miRNAs) are small non-coding RNAs that regulate gene expression by either blocking translation or inducing degradation of target mRNA. miRNAs play essential roles in diverse biological and pathological processes, including development of hepatic fibrosis. Hepatic stellate cells (HSCs) play a central role in development of hepatic fibrosis and there are intricate regulatory effects of miRNAs on their activation, proliferation, collagen production, migration, and apoptosis. There are multiple differentially expressed miRNAs in activated HSCs, and in this review we aim to summarize current data on miRNAs that participate in the development of hepatic fibrosis. Based on this review, miRNAs may serve as biomarkers for diagnosis of liver disease, as well as markers of disease progression. Most importantly, dysregulated miRNAs may potentially be targeted by novel therapies to treat and reverse progression of hepatic fibrosis.

miRNA for diagnosis and clinical implications of human hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most prevalent malignancies, as a result of being asymptomatic at early stage, subsequent late clinical confirmation and poor prognosis. It is urgent to search more accurate biomarkers for diagnosing early HCC and predicting prognosis. Many factors participate in liver carcinogenesis, including dysregulation of miRNA. miRNA were endogenously expressed non-coding single-stranded small RNA with 19-25 nucleotides. Accumulating evidences have showed that miRNA from circulation and solitary tumors may be useful to classify the differentiation degree and stages of HCC, detect the hepatitis B/C virus-related HCC, and predict the survival rate after surgical resection or orthotopic liver transplantation. In this review, we summarize dysregulated miRNA, their roles in diagnosis and clinical implications of HCC.

Na/K-ATPase signaling regulates collagen synthesis through microRNA-29b-3p in cardiac fibroblasts

Chronic kidney disease (CKD) is accompanied by cardiac fibrosis, hypertrophy, and dysfunction, which are commonly referred to as uremic cardiomyopathy. Our previous studies found that Na/K-ATPase ligands or 5/6th partial nephrectomy (PNx) induces cardiac fibrosis in rats and mice. The current study used in vitro and in vivo models to explore novel roles for microRNA in this mechanism of cardiac fibrosis formation. To accomplish this, we performed microRNA profiling with RT-qPCR based arrays on cardiac tissue from rats subjected to marinobufagenin (MBG) infusion or PNx. The analysis showed that a series of fibrosis-related microRNAs were dysregulated. Among the dysregulated microRNAs, microRNA (miR)-29b-3p, which directly targets mRNA of collagen, was consistently reduced in both PNx and MBG-infused animals. In vitro experiments demonstrated that treatment of primary cultures of adult rat cardiac fibroblasts with Na/K-ATPase ligands induced significant increases in the fibrosis marker, collagen protein, and mRNA expression compared with controls, whereas miR-29b-3p expression decreased >50%. Transfection of miR-29b-3p mimics into cardiac fibroblasts inhibited cardiotonic steroids-induced collagen synthesis. Moreover, a specific Na/K-ATPase signaling antagonist, pNaKtide, prevented ouabain-induced increases in collagen synthesis and decreases in miR-29b-3p expression in these cells. In conclusion, these data are the first to indicate that signaling through Na/K-ATPase regulates miRNAs and specifically, miR-29b-3p expression both in vivo and in vitro. Additionally, these data indicate that miR-29b-3p expression plays an important role in the formation of cardiac fibrosis in CKD.

MiR-146a-5p suppresses activation and proliferation of hepatic stellate cells in nonalcoholic fibrosing steatohepatitis through directly targeting Wnt1 and Wnt5a

Nonalcoholic fibrosing steatohepatitis is a uniform process throughout nonalcoholic fatty liver disease (NAFLD). MicroRNAs (miRNAs) have been suggested to modulate cellular processes in liver diseases. However, the functional role of miRNAs in nonalcoholic fibrosing steatohepatitis is largely unclear. In this study, we systematically analyzed the hepatic miRNAs by microarray analysis in nonalcoholic fibrosing steatohepatitis in C57BL/6J mice induced by methionine-choline deficient (MCD) diet. We identified 19 up-regulated and 18 down-regulated miRNAs in liver with fibrosis. Among these dysregulated miRNAs, miR-146a-5p was the most significant down-regulated miRNA. Luciferase activity assay confirmed that Wnt1 and Wnt5a were both the target genes of miR-146a-5p. Hepatic miR-146a-5p was down-regulated in fibrosing steatohepatitis, but its target genes Wnt1 and Wnt5a and their consequent effectors α-SMA and Col-1 were significantly up-regulated. In addition, miR-146a-5p was downregulated, whilst Wnt1 and Wnt5a were up-regulated in the activated primary hepatic stellate cells (HSCs) compared to the quiescent primary HSCs. Overexpression of miR-146a-5p in HSCs inhibited HSC activation and proliferation, which concomitant with the decreased expressions of Wnt1, Wnt5a, α-SMA and Col-1. In conclusion, miR-146a-5p suppresses activation and proliferation of HSCs in the progress of nonalcoholic fibrosing steatohepatitis through targeting Wnt1 and Wnt5a and consequent effectors α-SMA and Col-1.

Non-coding RNA-mediated epigenetic regulation of liver fibrosis

Hepatic stellate cells (HSC) activation plays a key role in liver fibrosis. Numerous studies have indicated that non-coding RNAs (ncRNAs) control liver fibrosis and fibroblasts proliferation. Greater knowledge of the role of the ncRNAs-mediated epigenetic mechanism in liver fibrosis could improve understanding of the liver fibrosis pathogenesis. The aim of this review is to describe the present knowledge about the ncRNAs significantly participating in liver fibrosis and HSC activation, and look ahead on new perspectives of ncRNAs-mediated epigenetic mechanism research. Moreover, we will discuss examples of non-coding RNAs that interact with histone modification or DNA methylation to regulate gene expression in liver fibrosis. Diverse classes of ncRNAs, ranging from microRNAs (miRs) to long non-coding RNAs (LncRNAs), have emerged as key regulators of several important aspects of function, including cell proliferation, activation, etc. In addition, recent advances suggest the important role of ncRNAs transcripts in epigenetic gene regulation. Targeting the miRs and LncRNAs can be a promising direction in liver fibrosis treatment. We discuss new perspectives of miRs and LncRNAs in liver fibrosis and HSC activation, mainly including interaction with histone modification or DNA methylation to regulate gene expression. These epigenetic mechanisms form powerful ncRNAs surveillance systems that may represent new targets for liver fibrosis therapeutic intervention.

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.

Loss of MicroRNA-101 Promotes Epithelial to Mesenchymal Transition in Hepatocytes

Epithelial-to-mesenchymal transition (EMT) has been implicated in embryonic development and various pathological events. However, the involvement of microRNA in the process of EMT remains to be fully defined in hepatocyte. ZEB1 is a well-known transcriptional repressor of E-cadherin and plays a major role in triggering EMT during organ fibrosis and cancer cell metastasis. Computational microRNA target predictions detect a conserved sequence matching to miR-101 in the 3'UTR of ZEB1 mRNA. Our results confirm that miR-101 suppresses ZEB1 expression by targeting the predicted site of ZEB1 3'UTR. Subsequent investigations show that miR-101 is significantly downregulated in the cultured hepatocytes undergoing EMT and in the hepatocytes isolated from fibrotic liver. Along with the loss of miR-101, the ZEB1 expression increases simultaneously in hepatocytes. In addition, miR-101 levels in HCC cell lines are negatively associated with the ZEB1 productions and the metastatic potentials of tumor cells. Mechanistically, we demonstrate that miR-101 significantly inhibits the TGF-β1-induced EMT in hepatocytes, whereas inhibition of miR-101 promotes the EMT process as indicated by the changes of morphology, cell migration, and the expression profiles of EMT markers. In the fibrotic liver, ectopic expression of miR-101 can significantly downregulate ZEB1 in the hepatocyte and thereby reduces the mesenchymal marker expression. Moreover, miR-101 significantly inhibits the proliferation and migration of HCC cell. Our results demonstrate that miR-101 regulates HCC cell phenotype by upregulating the epithelial marker genes and suppressing the mesenchymal ones.

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.

miR-30c and miR-193 are a part of the TGF-β-dependent regulatory network controlling extracellular matrix genes in liver fibrosis

OBJECTIVE

MicroRNAs (miRNAs) have recently emerged as novel regulators in liver fibrosis. miR-30c and miR-193 are involved in fibrotic remodeling processes and cancer development, respectively. This study aimed to explore the role of miR-30c and miR-193 in liver fibrosis.

METHODS

The regulation of miRNAs in carbon tetrachloride-induced liver fibrosis was analyzed by microarray. Expression patterns of miR-193 and miR-30c were further confirmed in fibrotic liver samples obtained from two murine models of hepatic fibrosis and human tissues. On a functional level, miRNA levels were analyzed in the context of transforming growth factor (TGF-β) mediated activation of hepatic stellate cells (HSCs). Finally, predicted targets were assessed for their roles in fibrosis by transfecting murine HSCs with miRNA mimics.

RESULTS

Microarray analysis in murine fibrotic livers revealed a panel of 44 dysregulated miRNAs. In addition to previously established miRNAs known to be regulated in liver fibrosis in a TGF-β-dependent manner (e.g., miR-29, miR-133), miR-193 and miR-30c were observed to be specifically downregulated not only in experimental hepatofibrogenesis but also in human liver fibrosis, while they showed a reciprocal expression pattern after recovery from liver fibrosis. Functional experiments confirmed the TGF-β-dependent downregulation of these respective new miRNAs in HSCs. Finally, we identified TGF-β2 and SNAIL1, important regulators of extracellular matrix, as potential target genes of miR-193 and miR-30 in liver fibrosis.

CONCLUSION

These results suggest that miR-30 and miR-193 are members of a network of miRNAs modifying the TGF-β-dependent regulation of extracellular matrix-related genes in HSCs in the manifestation and resolution of liver fibrosis.

The role of miRNAs in stress-responsive hepatic stellate cells during liver fibrosis

The progression of liver fibrosis and cirrhosis is associated with the persistence of an injury causing agent, leading to changes in the extracellular environment and a disruption of the cellular homeostasis of liver resident cells. Recruitment of inflammatory cells, apoptosis of hepatocytes, and changes in liver microvasculature are some examples of changing cellular environment that lead to the induction of stress responses in nearby cells. During liver fibrosis, the major stresses include hypoxia, oxidative stress, and endoplasmic reticulum stress. When hepatic stellate cells (HSCs) are subjected to such stress, they modulate fibrosis progression by induction of their activation toward a myofibroblastic phenotype, or by undergoing apoptosis, and thus helping fibrosis resolution. It is widely accepted that microRNAs are import regulators of gene expression, both during normal cellular homeostasis, as well as in pathologic conditions. MicroRNAs are short RNA sequences that regulate the gene expression by mRNA destabilization and inhibition of mRNA translation. Specific microRNAs have been identified to play a role in the activation process of HSCs on the one hand and in stress-responsive pathways on the other hand in other cell types (Table 2). However, so far there are no reports for the involvement of miRNAs in the different stress responses linked to HSC activation. Here, we review briefly the major stress response pathways and propose several miRNAs to be regulated by these stress responsive pathways in activating HSCs, and discuss their potential specific pro-or anti-fibrotic characteristics.

The let-7g microRNA promotes follicular granulosa cell apoptosis by targeting transforming growth factor-β type 1 receptor

The intronic microRNA let-7g controls cell differentiation and proliferation during angiogenesis and oncogenesis. Here, we demonstrate that let-7g regulates granulosa cell (GC) apoptosis and follicular atresia in the pig ovary. Bioinformatics analyses and luciferase reporter assays showed that transforming growth factor-β type 1 receptor (TGFBR1) is a let-7g target. Overexpression of let-7g induced apoptosis of porcine GCs in vitro and repressed the mRNA and protein levels of TGFBR1, as well as the level of phosphorylated SMAD3 (p-SMAD3) protein. RNA interference-mediated knockdown of TGFBR1 and inhibitor LY2157299-mediated blocking of TGFBR1 significantly increased the rate of apoptosis of GCs and Caspase-3 activity. In addition, treatment of porcine GCs with TGF-β1 reduced the level of let-7g and increased the levels of the TGFBR1 mRNA and proteins significantly. Overall, these results demonstrate that let-7g regulates the apoptosis of GCs in the pig ovary by targeting TGFBR1 and down-regulating the TGF-β signaling pathway.

MicroRNA-17-5p activates hepatic stellate cells through targeting of Smad7

A considerable amount of research has focused on the roles of microRNAs (miRNA) in the pathophysiology of liver fibrosis in view of their regulatory effects on hepatic stellate cell (HSC) functions, including proliferation, differentiation, and apoptosis. Recently, miR-17-5p was shown to promote cell proliferation and migration in liver. Transforming growth factor-β1 (TGF-β1) has been characterized as the master fibrogenic cytokine that stimulates HSC activation and promotes progression of liver fibrosis. The issue of whether miR-17-5p plays a role in TGF-β1-induced hepatic fibrogenesis remains to be established. In this study, we demonstrated a dose-/time-dependent increase in miR-17-5p expression in TGF-β1-treated HSCs. Enhanced miR-17-5p expression was additionally observed in CCl4-induced rat liver fibrosis. Inhibition of miR-17-5p led to suppression of HSC proliferation induced by TGF-β1 without affecting cellular apoptosis. Notably, miR-17-5p was significantly associated with TGF-β1-induced expression of type I collagen and α-SMA in HSC. Furthermore, Smad7, a negative regulator of the TGF-β/Smad pathway, was confirmed as a direct target of miR-17-5p. Serum miR-17-5p levels were significantly higher in patients with cirrhosis, compared to healthy controls. Our results collectively indicate that miR-17-5p promotes HSC proliferation and activation, at least in part, via reduction of Smad7, supporting its potential utility as a novel therapeutic target for liver fibrosis.

Sodium Tanshinone IIA Sulfonate Ameliorates Bladder Fibrosis in a Rat Model of Partial Bladder Outlet Obstruction by Inhibiting the TGF-β/Smad Pathway Activation

Transforming growth factor (TGF)-β1 is known to play a pivotal role in a diverse range of biological systems including modulation of fibrosis in several organs. The precise role of TGF-β/Smad signaling in the progression of bladder fibrosis secondary to partial bladder outlet obstruction (PBOO) is yet to be conclusively. Using a rat PBOO model, we investigated TGF-β1 expression and exaimined whether sodium tanshinone IIA sulfonate (STS) could inhibit TGF-β/Smad signaling pathway activation and ameliorate bladder fibrosis. Forty-eight female Sprague-Dawley rats were randomly divided into three groups: sham operation group (n = 16), PBOO operation without STS treatment group (n = 16) and PBOO operation with STS treatment group (n = 16). Thirty-two rats underwent the operative procedure to create PBOO and subsequently received intraperitoneal injections of STS (10 mg/kg/d; n = 16) or vehicle (n = 16) two days after the surgery. Sham surgery was conducted on 16 rats, which received intraperitoneal vehicle injection two days later. In each of the three groups, an equal number of rats were sacrificed at weeks 4 and 8 after the PBOO or sham operation. The TGF-β/Smad signaling pathway was analyzed using western blotting, immunohistochemical staining and reverse transcriptase polymerase chain reaction (RT-PCR). One-way analysis of variance was conducted to draw statistical inferences. At 4 and 8 weeks, the expression of TGF-β1 and phosphorylated Smad2 and Smad3 in STS-treated PBOO rats was significantly lower than in the PBOO rats not treated with STS. Alpha smooth muscle actin (α-SMA), collagen I and collagen III expression at 4 and 8 weeks post PBOO was lower in STS-treated PBOO rats when compared to that in PBOO rats not treated with STS. Our findings indicate that STS ameliorates bladder fibrosis by inhibiting TGF-β/Smad signaling pathway activation, and may prove to be a potential therapeutic measure for preventing bladder fibrosis secondary to PBOO operation.

miR-330-3p controls cell proliferation by targeting early growth response 2 in non-small-cell lung cancer

Non-small-cell lung cancer (NSCLC) is one of the most common lung cancers, and microRNAs (miRNAs) have been reported to play essential roles in NSCLC. Recent studies have indicated that miR-330-3p expression is up-regulated in NSCLC samples and in tissues of NSCLC brain metastasis. In this study, up-regulation of miR-330-3p expression was confirmed in NSCLC and 20 NSCLC patient samples. Furthermore, miR-330-3p was over-expressed in NSCLC cell lines A549 and H23, and the promotive function of miR-330-3p was investigated in regulating NSCLC cell proliferation and cell cycle distribution. To identify potential target genes of miR-330-3p in NSCLC, the miRNA target prediction databases were used. Luciferase activity assay and real-time RT-PCR analysis confirmed that miR-330-3p is negatively correlated with the expression of early growth response 2 (EGR2). Moreover, it was also found that EGR2 mRNA contains two potential binding sites for miR-330-3p. Knock-down of EGR2 with siRNA was demonstrated to have a similar effect as the over-expression of miR-330-3p in NSCLC cell lines. Taken together, our results show that EGR2 is a target of miR-330-3p.

MicroRNA-101 overexpression by IL-6 and TNF-α inhibits cholesterol efflux by suppressing ATP-binding cassette transporter A1 expression

BACKGROUND

MicroRNAs play key roles in regulating cholesterol homeostasis. Here, we investigated the role of microRNA-101 (miR-101) in regulating ATP-binding cassette transporter A1 (ABCA1) expression and cholesterol efflux under non-inflammatory and inflammatory conditions in human THP-1-derived macrophages and HepG2 hepatoblastoma cells.

METHODS

The cell lines were transfected with one of four lentiviral vectors: miR-101, miR-101 control, anti-miR-101, or anti-miR-101 control. A luciferase reporter assay was used to examine miR-101 binding to the 3' untranslated region (UTR) of ABCA1. Western blotting was conducted to assess ABCA1 protein expression. Cells were loaded with BODIPY-cholesterol and stained with oil red O to assess cholesterol efflux.

RESULTS

The luciferase activity assay revealed that wild-type miR-101 binding at site 2 significantly repressed ABCA1 3' UTR activity, suggesting that miR-101 directly targets the ABCA1 mRNA at site 2. In both cell lines, Western blotting revealed that miR-101 expression negatively regulates ABCA1 protein expression and significantly suppresses cholesterol efflux to ApoA1 under both low-density lipoprotein (LDL) and non-LDL conditions, which was confirmed by pronounced lipid inclusions visible by oil red O staining. In HepG2 cells, both IL-6 and TNF-α treatments produced significant miR-101 overexpression; however, in THP-1-derived macrophages, only IL-6 treatment produced significant miR-101 overexpression. Anti-mir-101 transfection under both IL-6 and TNF-α treatment conditions led to ABCA1 upregulation, indicating that miR-101 expression represses ABCA1 expression under inflammatory conditions.

CONCLUSIONS

miR-101 promotes intracellular cholesterol retention under inflammatory conditions through suppressing ABCA1 expression and suggests that the miR-101-ABCA1 axis may play an intermediary role in the development of NAFLD and vascular atherosclerosis.

Upregulation of microRNA-126 in hepatic stellate cells may affect pathogenesis of liver fibrosis through the NF-κB pathway

Hepatic fibrosis, which results from chronic liver disease, currently lacks effective treatment. MicroRNAs, a group of small noncoding RNA molecules, have been observed to play an essential role in liver diseases, including hepatic fibrosis. In this study, we described the regulation of nuclear factor kappa B (NF-κB) inhibitor alpha (IκBα) and its possible signaling pathway by miR-126 in human hepatic stellate cell (HSC) line LX-2. The 3'-untranslated region (3'-UTR) of IκBα combined with miR-126 was analyzed by using a dual-luciferase reporter assay. Furthermore, the effects of miR-126 on IκBα mRNA and protein and NF-κB protein expression were assessed by real-time quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) and western blot analysis in the human HSC LX-2 cell line transfected with miR-126 mimic or inhibitor. Moreover, to understand the molecular mechanism of miR-126 in promoting liver fibrosis through NF-κB signaling pathway, the NF-κB downstream signaling factors expression such as transforming growth factor (TGF)-β1 and collagen I mRNA were detected by real-time qRT-PCR. We identified that IκBα is a potential target gene of miR-126, by directly targeting its 3'-UTR. Endogenous miR-126 and exogenous miR-126 mimic inhibited IκBα expression. Moreover, overexpression of miR-126 reduced total and the cytoplasm IκBα protein expression and increased total and cytoblast NF-κB protein expression of LX-2. Conversely, knockdown of miR-126 could inhibit NF-κB activation by upregulation of IκBα protein expression. Further, miR-126 promoted TNF-a-induced TGF-β1 and collagen I mRNA expression in LX-2 cells. miR-126 may play an important role in hepatic fibrosis by downregulating the expression of IκBα partly through the NF-κB signaling pathway.