MicroRNA-200a controls Nrf2 activation by target Keap1 in hepatic stellate cell proliferation and fibrosis

Antifibrotic potential of reserpine (alkaloid) targeting Keap1/Nrf2; oxidative stress pathway in CCl4-induced liver fibrosis

The death rate due to liver cancer approaches 2 million annually, the majority is attributed to fibrosis. Currently, there is no efficient, safe, non-toxic, and anti-fibrotic drug available, suggesting room for better drug discovery. The current study aims to evaluate the anti-fibrotic role of reserpine, an alkaloid plant compound against CCl4-induced liver fibrosis. In-silico docking analysis showed the interaction of reserpine with keap1 protein with the binding energy -9.0 kcal/mol. In-vitro, biochemical analysis, anti-oxidative indexes, and inflammatory cytokines analysis were performed in HepG2 cells. The non-toxic nature of the compound (<100 μg/ml) was evaluated through MTT assay in HepG2 and Vero cell lines. The antifibrotic potential of the reserpine compound (dose of 0.5 mg/kg) was assessed in CCl4-administered C57BL/6J mice models. Hematoxylin & Eosin and Masson staining were performed to study the morphological changes of liver tissues. Immune histochemistry (IHC) analysis was performed to evaluate the effect of reserpine on the liver fibrosis marker. The biochemical assay indicated a significant decrease in ALT, AST, and MDA levels and increased catalase enzyme post-6-week reserpine treatment in mice models. Gene expression analysis revealed that the reserpine targets oxidative stress Keap1/Nrf2 pathway and down-regulated Keap1 expression by 5-fold and up-regulated Nrf2 and Nqo1 expression by 6 and 4.5-fold respectively showing its antioxidant response. It suppressed the expression of Cyp2e1 by 2.2-fold, illustrating the compound's ability to block lipid peroxidation. Histological and immunostaining exhibited improved hepatocyte morphology and reduced collagen deposition in liver tissues due to reserpine. Reserpine treatment lowered the fibrotic markers α-SMA and Col-1 by 1.3 and 1.5 folds respectively as compared to the control group and increased the expression of miR-200a and miR-29b by 15.5 and 8.2 folds (p < 0.05) while decreased miR-128-1-5p expression by 5-fold. A comprehensive In-silico, In-vitro, and In-vivo analysis revealed that reserpine has a strong anti-fibrotic effect against the CCl4-induced liver fibrosis in C57BL/6J mice model by targeting the Keap1/Nrf2 pathway.

Cutting-edge insights into liver fibrosis: advanced therapeutic strategies and future perspectives using engineered mesenchymal stem cell-derived exosomes

Liver fibrosis is still a serious health concern worldwide, and there is increasing interest in mesenchymal stem cells (MSCs) with tremendous potential for treating this disease because of their regenerative and paracrine effects. Recently, many researches have focused on using the released exosomes (EXOs) from stem cells to treat liver fibrosis rather than using parent stem cells themselves. MSC-derived EXOs (MSC-EXOs) have demonstrated favourable outcomes similar to cell treatment in terms of regenerative, immunomodulatory, anti-apoptotic, anti-oxidant, anti-necroptotic, anti-inflammatory and anti-fibrotic actions in several models of liver fibrosis. EXOs are superior to their parent cells in several terms, including lower immunogenicity and risk of tumour formation. However, maintaining the stability and efficacy of EXOs after in vivo transplantation remains a major challenge in their clinical applicability. Therefore, several strategies have been applied in EXOs engineering, such as parental cell modification or modifying EXOs directly to achieve optimum performance of EXOs in treating liver fibrosis. Herein, we discuss the underlying mechanisms of liver fibrosis with an overview of the available therapies, among them EXOs. We also summarise the recent developments in improving the effectiveness of EXOs with the advantages and limitations of these approaches in terms of the upcoming clinical applications.

miR-8-3p regulates the antioxidant response and apoptosis in white shrimp, Litopenaeus vannamei under ammonia-N stress

Exposure to excess ammonia-N (NH3/NH4+) in aquaculture can disrupt physiological function in shrimp leading to enhanced oxidative stress and apoptosis, but little is known concerning the post-transcriptional regulation mechanism. In this study, the first miR-200 family member in crustacean was identified and characterized from Litopenaeus vannamei (designed as Lva-miR-8-3p). Lva-miR-8-3p was highly expressed in eyestalks, brainganglion, and gills. The expression of Lva-miR-8-3p in gills significantly decreased after ammonia-N stress, and Lva-miR-8-3p was confirmed to target IKKβ 3'UTR for negatively regulating IKKβ/NF-κB pathway. Overexpression of miR-8-3p promoted the hemolymph ammonia-N accumulation, total hemocyte count (THC) decrease, and gills tissue damage, thus resulting in a decreased survival rate of ammonia-exposed shrimp. Besides, Lva-miR-8-3p silencing could enhance the antioxidant enzymes activities and reduce the oxidative damage, whereas overexpression of Lva-miR-8-3p exerted the opposite effects. Furthermore, Lva-miR-8-3p overexpression was found to aggravate ammonia-N induced apoptosis in gills. In primarily cultured hemocytes, the cell viability decreased, the ROS content and caspase-3 activity increased after agomiR-8-3p transfection, while antagomiR-8-3p transfection caused the opposite change except the cell viability. These findings indicate that Lva-miR-8-3p acts as a post-transcriptional regulator in ammonia-N induced antioxidant response and apoptosis by negatively regulating IKKβ/NF-κB pathway.

Comparative analysis of miRNAs and mRNAs in large yellow croaker head kidney cells (LYCK) provided novel insights into the redox regulation of fish

Reactive oxygen species (ROS) over-production and oxidative stress resulted from climate change and environmental pollution seriously endangered global fish populations and healthy development of marine aquaculture. Peroxiredoxins (Prxs), a highly conserved family of thiol-specific antioxidants, can mitigate ROS and protect cells from oxidative stress. We previously demonstrated that large yellow croaker PrxIV (LcPrxIV) could not only regulate the pro-inflammatory responses, but also scavenge ROS. However, the underlying mechanism how LcPrxIV regulated immune response and redox homeostasis remains unknown. MicroRNAs (miRNAs) are non-coding RNAs that play important roles in the regulation of various biological processes. In this study, mRNA and miRNA expression profiles from LYCK-pcDNA3.1 and LYCK-PrxIV cells, with or without oxidative stress stimulated by H2O2 were evaluated using high-throughput sequencing. A series of differentially expressed miRNAs (DEMs) and differentially expressed genes (DEGs), as well as DEM-DEG pairs were identified from each two-group comparison, respectively. GO and KEGG functional analyses indicated that most significant DEGs were associated with signaling pathways related to oxidative stress and immune response. Subsequent DEM-DEG interaction analysis revealed that miR-731 and miR-1388 may be involved in both redox regulation and immune response via synergistic effect with LcPrxIV. Interestingly, miR-731 could regulate the expression of different down-stream DEGs under different stimulations of LcPrxIV over-expression, H2O2, or both. Moreover, miR-731 could cause the DEG, γ-glutamyl hydrolase (GGH), to be expressed in opposite ways under different stimulations. On the other hand, the expression of miR-1388 could be negatively or positively regulated under the stimulation of LcPrxIV over-expression with or without oxidative stress, thus regulating gene expression of different mRNAs. Based on these results, we speculate that LcPrxIV may participate in immune response or redox regulation by regulating the expression of different down-stream genes through controlling the expression level of a certain miRNA or by regulating the varieties of expressed miRNAs.

A novel crosstalk between Nrf2 and Smad2/3 bridged by two nuanced Keap1 isoforms with their divergent effects on these distinct family transcription factors

The Keap1-Nrf2 signalling to transcriptionally regulate antioxidant response element (ARE)-driven target genes has been accepted as key redox-sensitive pathway governing a vast variety of cellular stresses during healthy survival and disease development. Herein, we identified two nuanced isoforms α and β of Keap1 in HepG2 cells, arising from its first and another in-frame translation starting codons, respectively. In identifying those differential expression genes monitored by Keap1α and/or Keap1β, an unusual interaction of Keap1 with Smad2/3 was discovered by parsing transcriptome sequencing, Keap1-interacting protein profiling and relevant immunoprecipitation data. Further examination validated that Smad2/3 enable physical interaction with Keap1, as well as its isoforms α and β, by both EDGETSD and DLG motifs in the linker regions between their MH1 and MH2 domains, such that the stability of Smad2/3 and transcriptional activity are enhanced with their prolonged half-lives and relevant signalling responses from the cytoplasmic to nuclear compartments. The activation of Smad2/3 by Keap1, Keap1α or Keap1β was much likely contributable to a coordinative or another competitive effect of Nrf2, particularly in distinct Keap1-based cellular responses to its cognate growth factor (i.e. TGF-β1) or redox stress (e.g. stimulated by tBHQ and DTT). Overall, this discovery presents a novel functional bridge crossing the Keap1-Nrf2 redox signalling and the TGF-β1-Smad2/3 pathways so as to coordinately regulate the healthy growth and development.

Mechanisms of Yajieshaba in the treatment of liver fibrosis through the Keap1-Nrf2 signaling pathway

Yajieshaba (YJSB), a traditional Dai medicine formula containing botanical drugs, is commonly employed in Yunnan due to its significant therapeutic effects on liver protection. Consequently, to determine the efficacy of YJSB and the mechanism of action of Kelch-like ECH-associated protein 1 (Keap1)-nuclear factor erythroid 2-related factor 2 (Nrf2) pathway against liver fibrosis. We wanted to see if YJSB could treat CCl₄-induced liver fibrosis by regulating the Keap1-Nrf2 signaling pathway. YJSB significantly improved liver function biochemical indices, liver fibrosis quadruple, hydroxyproline (Hyp), and transforming growth factor-β1 (TGF-β1) levels. The staining results demonstrated that the degree of liver fibrosis was significantly reduced. YJSB reduced the content of malondialdehyde (MDA) and elevated the content of superoxide dismutase (SOD) in the liver, exhibiting antioxidant effects; meanwhile, it regulated the expression of Keap1-Nrf2 pathway protein, increased the expression of NAD(P)H: Quinone oxidoreductase (NQO1), Heme Oxygenase 1 (HO-1), Glutamate cysteine ligase modifier subunit (GCLM), and Glutamate cysteine ligase catalytic subunit (GCLC) expression in the liver decreased while Nrf2 expression increased. Fluorescence immunoassay studies demonstrated that YJSB promoted the trans-nuclearization of Nrf2. YJSB possesses anti-liver fibrosis pharmacological effects that improve liver function and effectively counteract CCl₄-induced liver fibrosis damage. The mechanism of action might be related to the regulation of protein expression of the Keap1-Nrf2 pathway, increasing the ability of the body to resist oxidative stress and reduce oxidative stress injury.

Modulatory effect of rupatadine on mesenchymal stem cell-derived exosomes in hepatic fibrosis in rats: A potential role for miR-200a

AIMS

Mesenchymal stem cell-derived exosomes (MSC-EXOs) have emerged as a promising approach in regenerative medicine for management of different diseases. However, the maintenance of their efficacy after in vivo transplantation is still a major concern. The present investigation aimed to assess the modulatory effect of rupatadine (RUP) on MSC-EXOs in diethylnitrosamine (DEN)-induced liver fibrosis (LF), and to explore the possible underlying mechanism.

MAIN METHODS

LF was induced in rats by i.p. injection of DEN (100 mg/kg) once per week for 6 successive weeks. Rats were then treated with RUP (4 mg/kg/day, p.o.) for 4 weeks with or without a single i.v. administration of MSC-EXOs. At the end of the experiment, animals were euthanized and serum and liver were separated for biochemical, and histological measurements.

KEY FINDINGS

The combined MSC-EXOs/RUP therapy provided an additional improvement towards inhibition of DEN-induced LF compared to MSC-EXOs group alone. These outcomes could be mediated through antioxidant, anti-inflammatory, and anti-fibrotic effects of RUP which created a more favorable environment for MSC-EXOs homing, and action. This in turn would enhance more effectively miR-200a expression which reduced oxidative stress, inflammation, necroptosis pathway, and subsequently fibrosis as revealed by turning off TGF-β1/α-SMA expression, and hedgehog axis.

SIGNIFICANCE

The present findings reveal that RUP enhanced the anti-fibrotic efficacy of MSC-EXOs when used as a combined therapy. This was revealed through attenuation of PAF/RIPK3/MLKL/HMGB1, and TGF-β1/hedgehog signaling pathways with a significant role for miR-200a.

Neuroprotective Capability of Narcissoside in 6-OHDA-Exposed Parkinson's Disease Models through Enhancing the MiR200a/Nrf-2/GSH Axis and Mediating MAPK/Akt Associated Signaling Pathway

We assessed the antioxidant potential of narcissoside from Sambucus nigra flowers (elderflowers) in Parkinson's disease models in vitro and in vivo. The results showed that narcissoside lessened the 6-hydroxydopamine (6-OHDA)-induced increase in reactive oxygen species (ROS) and apoptosis in SH-SY5Y cells. In the 6-OHDA-exposed Caenorhabditis elegans model, narcissoside reduced degeneration of dopaminergic neurons and ROS generation, and also improved dopamine-related food-sensitive behavior and shortened lifespan. Moreover, NCS increased total glutathione (GSH) by increasing the expression of the catalytic subunit and modifier subunit of γ-glutamylcysteine ligase in cells and nematodes. Treatment with a GSH inhibitor partially abolished the anti-apoptotic ability of narcissoside. Furthermore, narcissoside diminished the 6-OHDA-induced phosphorylation of JNK and p38, while rising activities of ERK and Akt in resisting apoptosis. The antioxidant response element (ARE)-luciferase reporter activity analysis and electromobility gel shift assay showed that narcissoside promotes the transcriptional activity mediated by Nrf2. Finally, we found that narcissoside augmented the expression of miR200a, a translational inhibitor of the Nrf2 repressor protein Keap1. Downregulation of Nrf2 and miR200a by RNAi and anti-miR200a, respectively, reversed the neuroprotective ability of narcissoside. In summary, narcissoside can enhance the miR200a/Nrf2/GSH antioxidant pathway, alleviate 6-OHDA-induced apoptosis, and has the neuroprotective potential.

An Axis between the Long Non-Coding RNA HOXA11-AS and NQOs Enhances Metastatic Ability in Oral Squamous Cell Carcinoma

Long non-coding RNAs (lncRNAs) play critical roles in human cancers. HOXA11 anti-sense RNA (HOXA11-AS) is an lncRNA belonging to the homeobox (HOX) gene cluster that promotes liver metastasis in human colon cancer. However, its role and mechanism of action in human oral squamous cell carcinoma (OSCC) are unclear. In this study, we investigated HOXA11-AS expression and function in human OSCC tissues and cell lines, as well as a mouse model of OSCC. Our analyses showed that HOXA11-AS expression in human OSCC cases correlates with lymph node metastasis, nicotinamide adenine dinucleotide (NAD)(P)H: quinone oxidoreductase 1 (NQO1) upregulation, and dihydronicotinamide riboside (NRH): quinone oxidoreductase 2 (NQO2) downregulation. Using the human OSCC cell lines HSC3 and HSC4, we demonstrate that HOXA11-AS promotes NQO1 expression by sponging microRNA-494. In contrast, HOXA11-AS recruits zeste homolog 2 (EZH2) to the NQO2 promoter to suppress its expression via the trimethylation of H3K27. The upregulation of NQO1 enzymatic activity by HOXA11-AS results in the consumption of flavin adenine dinucleotide (FAD), which reduces FAD-requiring glyceraldehyde-3-phosphate dehydrogenase (GAPDH) activity and suppresses glycolysis. However, our analyses show that lactic acid fermentation levels are preserved by glutaminolysis due to increased malic enzyme-1 expression, promoting enhanced proliferation, invasion, survival, and drug resistance. In contrast, suppression of NQO2 expression reduces the consumption of NRH via NQO2 enzymatic activity and increases NAD levels, which promotes enhanced stemness and metastatic potential. In mouse tumor models, knockdown of HOXA11-AS markedly suppressed tumor growth and lung metastasis. From these findings, targeting HOXA11-AS may strongly suppress high-grade OSCC by regulating both NQO1 and NQO2.

Roles of NRF2 in Fibrotic Diseases: From Mechanisms to Therapeutic Approaches

Fibrosis is a persistent inflammatory response that causes scarring and tissue sclerosis by stimulating myofibroblasts to create significant quantities of extracellular matrix protein deposits in the tissue. Oxidative stress has also been linked to the development of fibrosis in several studies. The nuclear erythroid 2-related factor 2 (NRF2) transcription factor controls the expression of several detoxification and antioxidant genes. By binding to antioxidant response elements, NRF2 is activated by oxidative or electrophilic stress and promotes its target genes, resulting in a protective effect on cells. NRF2 is essential for cell survival under oxidative stress conditions. This review describes Kelch-like epichlorohydrin-associated protein 1 (KEAP1)/NRF2 signaling mechanisms and presents recent research advances regarding NRF2 and its involvement in primary fibrotic lesions such as pulmonary fibrosis, hepatic fibrosis, myocardial fibrosis, and renal fibrosis. The related antioxidant substances and drugs are described, along with the mechanisms by which KEAP1/NRF2 regulation positively affects the therapeutic response. Finally, the therapeutic prospects and potential value of NRF2 in fibrosis are summarized. Further studies on NRF2 may provide novel therapeutic approaches for fibrosis.

The role of non-coding RNAs in ferroptosis regulation

Ferroptosis is a newly recognized form of cell death that is distinct from apoptosis, necrosis, autophagy in morphology, biochemistry, and heredity. The basic process of ferroptosis involves disordered permeability of plasma membrane, which is caused by abnormal accumulation of lipids and reactive oxygen species (ROS). The regulatory mechanism of ferroptosis is important due to its involvement in tumor progression, neurotoxicity, neurodegenerative diseases, acute renal failure, and ischemia-reperfusion injury. Recent studies have shown that in ferroptosis metabolism, non-coding RNAs (ncRNAs) can interfere with multiple signaling pathways at both the pre-transcriptional and post-transcriptional levels. Despite great progress, current research on the mechanism of ncRNAs and ferroptosis remains insufficient. This review provides an overview of the main mechanisms and targets of ferroptosis and focuses on the mechanisms of non-coding RNA regulation. Analyzing the deficiencies in current research may provide ideas for future studies to investigate.

Developmental Programming: Prenatal Testosterone Excess on Liver and Muscle Coding and Noncoding RNA in Female Sheep

Prenatal testosterone (T)-treated female sheep manifest peripheral insulin resistance, ectopic lipid accumulation, and insulin signaling disruption in liver and muscle. This study investigated transcriptional changes and transcriptome signature of prenatal T excess-induced hepatic and muscle-specific metabolic disruptions. Genome-wide coding and noncoding (nc) RNA expression in liver and muscle from 21-month-old prenatal T-treated (T propionate 100 mg intramuscular twice weekly from days 30-90 of gestation; term: 147 days) and control females were compared. Prenatal T (1) induced differential expression of messenger RNAs (mRNAs) in liver (15 down, 17 up) and muscle (66 down, 176 up) (false discovery rate < 0.05, absolute log2 fold change > 0.5); (2) downregulated mitochondrial pathway genes in liver and muscle; (3) downregulated hepatic lipid catabolism and peroxisome proliferator-activated receptor (PPAR) signaling gene pathways; (4) modulated noncoding RNA (ncRNA) metabolic processes gene pathway in muscle; and (5) downregulated 5 uncharacterized long noncoding RNA (lncRNA) in the muscle but no ncRNA changes in the liver. Correlation analysis showed downregulation of lncRNAs LOC114112974 and LOC105607806 was associated with decreased TPK1, and LOC114113790 with increased ZNF470 expression. Orthogonal projections to latent structures discriminant analysis identified mRNAs HADHA and SLC25A45, and microRNAs MIR154A, MIR25, and MIR487B in the liver and ARIH1 and ITCH and miRNAs MIR369, MIR10A, and MIR10B in muscle as potential biomarkers of prenatal T excess. These findings suggest downregulation of mitochondria, lipid catabolism, and PPAR signaling genes in the liver and dysregulation of mitochondrial and ncRNA gene pathways in muscle are contributors of lipotoxic and insulin-resistant hepatic and muscle phenotype. Gestational T excess programming of metabolic dysfunctions involve tissue-specific ncRNA-modulated transcriptional changes.

Epigenetic Regulation of Hepatic Stellate Cell Activation and Macrophage in Chronic Liver Inflammation

Chronic liver inflammation is a complex pathological process under different stress conditions, and the roles of stellate cells and macrophages in chronic liver inflammation have been widely reported. Moderate liver inflammation can protect the liver from damage and facilitate the recovery of liver injury. However, an inflammatory response that is too intense can result in massive death of hepatocytes, which leads to irreversible damage to the liver parenchyma. Epigenetic regulation plays a key part in liver inflammation. This study reviews the regulation of epigenetics on stellate cells and macrophages to explore the new mechanisms of epigenetics on liver inflammation and provide new ideas for the treatment of liver disease.

Epigenetics and microRNAs in UGT1As

UDP-glucuronosyltransferases (UGTs) are the main phase II drug-metabolizing enzymes mediating the most extensive glucuronidation-binding reaction in the human body. The UGT1A family is involved in more than half of glucuronidation reactions. However, significant differences exist in the distribution of UGT1As in vivo and the expression of UGT1As among individuals, and these differences are related to the occurrence of disease and differences in metabolism. In addition to genetic polymorphisms, there is now interest in the contribution of epigenetics and noncoding RNAs (especially miRNAs) to this differential change. Epigenetics regulates UGT1As pretranscriptionally through DNA methylation and histone modification, and miRNAs are considered the key mechanism of posttranscriptional regulation of UGT1As. Both epigenetic inheritance and miRNAs are involved in the differences in sex expression and in vivo distribution of UGT1As. Moreover, epigenetic changes early in life have been shown to affect gene expression throughout life. Here, we review and summarize the current regulatory role of epigenetics in the UGT1A family and discuss the relationship among epigenetics and UGT1A-related diseases and treatment, with references for future research.

Regulation of Nrf2 signaling pathway in heart failure: Role of extracellular vesicles and non-coding RNAs

The balance between pro- and antioxidant molecules has been established as an important driving force in the pathogenesis of cardiovascular disease. Chronic heart failure is associated with oxidative stress in the myocardium and globally. Redox balance in the heart and brain is controlled, in part, by antioxidant proteins regulated by the transcription factor Nuclear factor erythroid 2-related factor 2 (Nrf2), which is reduced in the heart failure state. Nrf2 can, in turn, be regulated by a variety of mechanisms including circulating microRNAs (miRNAs) encapsulated in extracellular vesicles (EVs) derived from multiple cell types in the heart. Here, we review the role of the Nrf2 and antioxidant enzyme signaling pathway in mediating redox balance in the myocardium and the brain in the heart failure state. This review focuses on Nrf2 and antioxidant protein regulation in the heart and brain by miRNA-enriched EVs in the setting of heart failure. We discuss EV-mediated intra- and inter-organ communications especially, communication between the heart and brain via an EV pathway that mediates cardiac function and sympatho-excitation in heart failure. Importantly, we speculate how engineered EVs with specific miRNAs or antagomirs may be used in a therapeutic manner in heart failure.

Induction of liver fibrosis by CCl4 mediates pathological alterations in the spleen and lymph nodes: The potential therapeutic role of propolis

In an animal models, carbon tetrachloride (CCl4) is a carcinogenic agent that causes liver fibrosis. The current study aims to investigate whether induction in liver-fibrosis by CCl4 in the mouse model could promote the initiation of fibrosis in lymph node and spleen due to sustained increase of inflammatory signals and also aimed to clarify the protective therapeutic effects of propolis. The male mice (BALB/c) were categorized into three experimental sets and each group involved 15 mice. Control group falls into first group; group-II and group-III were injected with CCl4 to induce liver-fibrosis and oral supplementation with propolis was provided in group-III for 4-weeks. A major improvement with hepatic collagen and α-smooth muscle actin (α-SMA) production was aligned with the activation of liver fibrosis from CCl4. Mice treated with CCl4 exhibited collagen deposition towards liver sections, pathological alterations in spleen and lymph node architectures, and a significantly increase the circulation of both T&B cells in secondary lymphoid organs. Mechanically, the secondary lymphoid organs treated with CCl4 in mice exposed a positive growth in α-SMA and collagen expression, increased in proinflammatory cytokine levels and a significant increase in TGF-β, NO and ROS levels. A manifest intensification in the expression of Nrf2, COX-2, and eNOS and upregulation of ASK1 and P38 phosphorylation. Interestingly, addition of propolis-treated CCl4 mice, substantially suppressed deposition of liver collagen, repealed inflammatory signals and resorted CCl4-mediated alterations in signaling cascades, thereby repairing the architectures of the secondary lymphoid organs. Our findings revealed benefits of propolis against fibrotic complications and enhancing secondary lymphoid organ architecture.

Prediction and verification of target of helenalin against hepatic stellate cell activation based on miR-200a-mediated PI3K/Akt and NF-κB pathways

Hepatic stellate cell (HSC) activation is a crucial event in the progress of liver fibrosis. In this study, the target of helenalin was firstly predicted by bioinformatics analysis, and then the prediction was verified by various experiments. HSC-T6 cells were activated by interleukin-1 beta (IL-1β) and then treated with helenalin. Moreover, HSC-T6 cells were transfected with miR-200a mimic or inhibitor, and the effect of helenalin on the miR-200a-mediated PI3K/Akt and NF-κB signaling pathways was investigated. The bioinformatics analysis indicated that miR-200a might regulate the PI3K/Akt pathway, NF-κB activation, Bcl-2 family and Caspases, ultimately affecting cell survival and apoptosis. Interestingly, the molecular docking demonstrated that the target of helenalin might be miR-200a-mediated the PI3K/Akt and NF-κB pathways. Moreover, the experiments showed that helenalin administration led to the inactivation of HSC-T6 cells, as evidenced by the inhibition of cell proliferation, α-SMA expression and collagen production. The mechanism studies showed that helenalin reduced collagen accumulation by restoring the balance of MMPs/TIMPs. Moreover, helenalin markedly suppressed HSC activation by inhibiting the PI3K/Akt pathway and alleviated inflammatory response by blocking the NF-κB signal transduction. Further study indicated that helenalin up-regulated miR-200a expression, thus leading to the inhibition of the PI3K/Akt and NF-κB signaling pathways. In conclusion, helenalin inhibits HSC activation via inhibiting the miR-200a-mediated PI3K/Akt and NF-κB pathways, and it may be developed as a potential medicine for the treatment of liver fibrosis.

MicroRNA-200a represses myocardial infarction-related cell death and inflammation by targeting the Keap1/Nrf2 and β-catenin pathways

BACKGROUND

Acute myocardial infarction (MI) is a main cause of emergency death in the world. MicroRNAs (miRs/miRNAs) are a series of small non-coding RNA molecules, which regulate cardiovascular disorders that involve MI. In this study, we explored the function of miR-200a in MI treatment.

METHODS

We observed down-regulation of miR-200a levels and up-regulation of Keap1 and β-catenin levels in H₂O₂-treated newborn murine ventricular cardiomyocytes (NMVCs) and the infarcted heart tissues of MI mouse models, compared to the non-treated NMVCs and normal heart tissues of healthy mice.

RESULTS

CCK-8 and colony formation assays indicated the reduction in NMVC vitality due to H₂O₂ treatment and the recovery of cell vitality due to miR-200a overexpression, respectively. Flow cytometry with Annexin and PI staining indicated the inhibition of H₂O₂-triggered cell apoptosis through ectopically expressed miR-200a. Western blotting and ELISA analyses that detected pro-inflammatory cell factors [interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α] confirmed that miR-200a prevented H₂O₂-induced NMVC inflammation. Moreover, miR-200a inhibited up-regulation of Keap1 and β-catenin expression in H₂O₂-treated NMVCs by directly binding with the 3'-UTR regions of both Keap1 and β-catenin. Furthermore, overexpression of Keap1 and β-cateninin in H₂O₂-treated NMVCs with recovered miR-200a elevated inflammation and apoptosis, respectively.

CONCLUSION

The results showed that miR-200a expression was inhibited in murine cardiomyocytes due to H₂O₂ stress in MI cardiac tissues and overexpressed miR-200a could protect the cells from death by regulating the Keap1/Nrf2 and β-catenin signal transduction pathways.

Roles of Nrf2 in Liver Diseases: Molecular, Pharmacological, and Epigenetic Aspects

Liver diseases represent a critical health problem with 2 million deaths worldwide per year, mainly due to cirrhosis and its complications. Oxidative stress plays an important role in the development of liver diseases. In order to maintain an adequate homeostasis, there must be a balance between free radicals and antioxidant mediators. Nuclear factor erythroid 2-related factor (Nrf2) and its negative regulator Kelch-like ECH-associated protein 1 (Keap1) comprise a defense mechanism against oxidative stress damage, and growing evidence considers this signaling pathway as a key pharmacological target for the treatment of liver diseases. In this review, we provide detailed and updated evidence regarding Nrf2 and its involvement in the development of the main liver diseases such as alcoholic liver damage, viral hepatitis, steatosis, steatohepatitis, cholestatic damage, and liver cancer. The molecular and cellular mechanisms of Nrf2 cellular signaling are elaborated, along with key and relevant antioxidant drugs, and mechanisms on how Keap1/Nrf2 modulation can positively affect the therapeutic response are described. Finally, exciting recent findings about epigenetic modifications and their link with regulation of Keap1/Nrf2 signaling are outlined.

Beyond repression of Nrf2: An update on Keap1

Nrf2 (NFE2L2 - nuclear factor (erythroid-derived 2)-like 2) is a transcription factor, which is repressed by interaction with a redox-sensitive protein Keap1 (Kelch-like ECH-associated protein 1). Deregulation of Nrf2 transcriptional activity has been described in the pathogenesis of multiple diseases, and the Nrf2/Keap1 axis has emerged as a crucial modulator of cellular homeostasis. Whereas the significance of Nrf2 in the modulation of biological processes has been well established and broadly discussed in detail, the focus on Keap1 rarely goes beyond the regulation of Nrf2 activity and redox sensing. However, recent studies and scrutinized analysis of available data point to Keap1 as an intriguing and potent regulator of cellular function. This review aims to shed more light on Keap1 structure, interactome, regulation and non-canonical functions, thereby enhancing its significance in cell biology. We also intend to highlight the impact of balance between Keap1 and Nrf2 in the maintenance of cellular homeostasis.

MicroRNA-based regulatory mechanisms underlying the synergistic antioxidant action of quercetin and catechin in H2O2-stimulated HepG2 cells: Roles of BACH1 in Nrf2-dependent pathways

The microRNA-based mechanisms underlying the antioxidant action(s) of co-existing flavonoids in response to oxidative stress are of high interest. This study aimed to extend the existing knowledge and provide insights into the potential regulatory network in response to oxidative stress and the co-presence of quercetin and catechin antioxidants, via a preclinical approach using H₂O₂-stimulated HepG2 cells. It was confirmed that BACH1 serves as an essential and direct negative regulator of the Keap1-Nrf2 signaling pathway and the antioxidant synergism between quercetin and catechin. BACH1 promoted reactive oxygen species (ROS) accumulation while inhibiting cell growth, which could be reversed by the synergistic action of let-7a-5p and miR-25-3p in the co-presence of quercetin and catechin. Both let-7a-5p and miR-25-3p could directly regulate the expression and function of BACH1 (e.g. upregulation of the two miRNAs could rescue largely overexpression of BACH1). Although these molecular interactions likely represented only some aspects of the overall regulatory network, this research confirms the feasibility of the combined uses of dietary flavonoids with chemopreventive properties in synergy during multiple-target interactions and multiple-pathway regulation.

miRNAs, oxidative stress, and cancer: A comprehensive and updated review

Oxidative stress refers to elevated levels of intracellular reactive oxygen species (ROS). ROS homeostasis functions as a signaling pathway for normal cell survival and appropriate cell signaling. Chronic inflammation induced by imbalanced levels of ROS contributes to many diseases and different types of cancer. ROS can alter the expression of oncogenes and tumor suppressor genes through epigenetic modifications, transcription factors, and non-coding RNAs. MicroRNAs (miRNAs) are small non-coding RNAs that play a key role in most biological pathways. Each miRNA regulates hundreds of target genes by inhibiting protein translation and/or promoting messenger RNA degradation. In normal conditions, miRNAs play a physiological role in cell proliferation, differentiation, and apoptosis. However, different factors that can dysregulate cell signaling and cellular homeostasis can also affect miRNA expression. The alteration of miRNA expression can work against disturbing factors or mediate their effects. Oxidative stress is one of these factors. Considering the complex interplay between ROS level and miRNA regulation and both of these with cancer development, we review the role of miRNAs in cancer, focusing on their function in oxidative stress.

Upregulation of microRNA-200a in bone marrow mesenchymal stem cells enhances the repair of spinal cord injury in rats by reducing oxidative stress and regulating Keap1/Nrf2 pathway

Spinal cord injury (SCI) is a common disease with high incidence, disability rate and treatment cost. microRNA (miR)-200a is reported to inhibit Keap1 to activate Nrf2 signaling. This study aimed to explore the effects of lentivirus-mediated miR-200a gene-modified bone marrow mesenchymal stem cells (BMSCs) transplantation on the repair of SCI in a rat model. BMSCs were isolated from the bone marrow of Sprague-Dawley rats. MiR-200a targeting to Keap1 was identified by luciferase reporter gene assay. The expressions of Keap1, nuclear factor erythroid 2-related factor 2 (Nrf2), NAD(P)H-dependent quinone oxidoreductase 1 (NQO-1), heme oxygenase-1 (HO-1) and glutamate-cysteine ligase catalytic subunit (GCLC) were detected by Western blotting in SCI rats. The locomotor capacity of the rats was evaluated using the Basso, Beattie, and Bresnahan scale. The levels of malondialdehyde (MDA), activities of superoxide dismutase (SOD), and catalase (CAT) were measured. miR-200a inhibited Keap-1 3' UTR activity in BMSCs. Transplantation of BMSCs with overexpression of miR-200a or si-Keap1 increased locomotor function recovery of rats after SCI, while decreased MDA level, increased SOD, CAT activities, and Nrf2 expression together with its downstream HO-1, NQO1, GCLC protein expressions in SCI rat. These results indicated that overexpressed miR-200a in BMSCs promoted SCI repair, which may be through regulating antioxidative signaling pathway.

Gli3 is a novel downstream target of miR‑200a with an anti‑fibrotic role for progression of liver fibrosis in vivo and in vitro

GLI family zinc finger 3 (Gli3), as the upstream transcriptional activator of hedgehog signaling, has previously been demonstrated to participate in the process of liver fibrosis. The present study aimed to investigate the potential functions of microRNA (miR)‑200a and Gli3 in the progression of liver fibrosis. The expression levels of miR‑200a and Gli3 in cells and tissues were determined by PCR and western blotting; the interaction of Gli3 and miR‑200a was evaluated by bioinformatics analysis and dual‑luciferase reporter assay. miR‑200a was significantly reduced in serum samples from clinical patients, liver tissues of a carbon tetrachloride (CCl4)‑induced rat model and activated LX2 cells. The expression of α‑smooth muscle actin (α‑SMA) and albumin at the mRNA and protein levels was increased and decreased in LX2 cells, respectively. However, the expression levels of α‑SMA and albumin were reversed and Gli3 expression was markedly decreased in LX2 cells when transfected with miR‑200a mimics. In addition, the dual‑-luciferase reporter assay confirmed the target interaction between miR‑200a and Gli3. Finally, following the administration of miR‑200a mimics to CCl4‑induced rats, it was revealed that the alterations of α‑SMA, albumin and Gli3 presented a similar trend to that in LX2 cells with miR‑200a mimics transfection. Taken together, these results indicated that downregulation of miR‑200a might enhance the formation of liver fibrosis, probably by targeting Gli3, and elevated miR‑200a may attenuate the progression of liver fibrosis by suppressing Gli3. These findings suggested that miR‑200a may function as a novel anti‑fibrotic agent in liver fibrosis via inhibition of the expression of Gli3.

miR-26b inhibits isoproterenol-induced cardiac fibrosis via the Keap1/Nrf2 signaling pathway

A critical event in cardiac fibrosis is the transformation of cardiac fibroblasts (CFs) into myofibroblasts. MicroRNAs (miRNAs) have been reported to be critical regulators in the development of cardiac fibrosis. However, the underlying molecular mechanisms of action of miRNA (miR)-26b in cardiac fibrosis have not yet been extensively studied. In the present study, the expression levels of miR-26b were downregulated in isoproterenol (ISO)-treated cardiac tissues and CFs. Moreover, miR-26b overexpression inhibited the cell viability of ISO-treated CFs and decreased the protein levels of collagen I and α-smooth muscle actin (α-SMA). Furthermore, bioinformatics analysis and dual luciferase reporter assays indicated that Kelch-like ECH-associated protein 1 (Keap1) was the target of miR-26b, and that its expression levels were decreased in miR-26b-treated cells. In addition, Keap1 overexpression reversed the inhibitory effects of miR-26b on ISO-induced cardiac fibrosis, as demonstrated by cell viability, and the upregulation of collagen I and α-SMA expression levels. Furthermore, inhibition of Keap1 expression led to the activation of nuclear factor erythroid 2-related factor 2 (Nrf2), which induced the transcriptional activation of antioxidant/detoxifying proteins in order to protect against cardiac fibrosis. Taken together, the data demonstrated that miR-26b attenuated ISO-induced cardiac fibrosis via the Keap-mediated activation of Nrf2.

Oxidative Stress-Responsive MicroRNAs in Heart Injury

Reactive oxygen species (ROS) are important molecules in the living organisms as a part of many signaling pathways. However, if overproduced, they also play a significant role in the development of cardiovascular diseases, such as arrhythmia, cardiomyopathy, ischemia/reperfusion injury (e.g., myocardial infarction and heart transplantation), and heart failure. As a result of oxidative stress action, apoptosis, hypertrophy, and fibrosis may occur. MicroRNAs (miRNAs) represent important endogenous nucleotides that regulate many biological processes, including those involved in heart damage caused by oxidative stress. Oxidative stress can alter the expression level of many miRNAs. These changes in miRNA expression occur mainly via modulation of nuclear factor erythroid 2-related factor 2 (Nrf2), sirtuins, calcineurin/nuclear factor of activated T cell (NFAT), or nuclear factor kappa B (NF-κB) pathways. Up until now, several circulating miRNAs have been reported to be potential biomarkers of ROS-related cardiac diseases, including myocardial infarction, hypertrophy, ischemia/reperfusion, and heart failure, such as miRNA-499, miRNA-199, miRNA-21, miRNA-144, miRNA-208a, miRNA-34a, etc. On the other hand, a lot of studies are aimed at using miRNAs for therapeutic purposes. This review points to the need for studying the role of redox-sensitive miRNAs, to identify more effective biomarkers and develop better therapeutic targets for oxidative-stress-related heart diseases.

Targeting Keap1 by miR-626 protects retinal pigment epithelium cells from oxidative injury by activating Nrf2 signaling

Activation of the NF-E2-related factor 2 (Nrf2) cascade can offer significant protection against oxidative stress in retinal pigment epithelium (RPE) cells. Here, we identified a novel kelch-like ECH-associated protein 1 (Keap1)-targeting microRNA, microRNA-626 (miR-626) that activates Nrf2 signaling. In ARPE-19 cells and primary human RPE cells, ectopic overexpression of miR-626 targeting the 3'-UTR (3'-untranslated region) of Keap1 downregulated its expression, promoting Nrf2 protein stabilization and nuclear translocation, leading to expression of ARE-dependent genes (HO1, NOQ1 and GCLC). Functional studies showed that miR-626 protected RPE cells from hydrogen peroxide (H₂O₂)-induced oxidative injury. Conversely, miR-626 inhibition induced Keap1 upregulation and Nrf2 cascade inhibition, exacerbating oxidative injury in RPE cells. Further studies demonstrated that miR-626 was ineffective in Keap1-knockout or Nrf2-knockout RPE cells. Importantly, miR-626 also activated Keap1-Nrf2 signaling cascade in human lens epithelial cells (HLECs) and primary human retinal ganglion cells (RGCs), providing protection from H₂O₂. At last, we show that plasma miR-626 levels are significantly downregulated in age-related macular degeneration (AMD) patients than those in the healthy donors. We conclude that targeting Keap1 by miR-626 protects RPE cells and other ophthalmic cells from oxidative injury via activation of Nrf2 signaling cascade.

Trehalose suppresses cadmium-activated Nrf2 signaling pathway to protect against spleen injury

Cadmium (Cd), as a kind of ubiquitous and highly toxic heavy metal pollutants, has been known to result in immunotoxicity in animals. As a multifunctional bioactivity disaccharide, trehalose (Tre) is characterized by antioxidative, antiapoptotic, and accelerating autophagy. In this study, Sprague-Dawley (SD) rats were fed with cadmium chloride (CdCl₂) and/or Tre to explore the molecular mechanisms of Tre-protected against spleen injury caused by Cd exposure. Firstly, the results showed that Tre partially recovered splenic pathological changes induced by Cd exposure. Secondly, Tre dramatically declined the level of methane dicarboxylic aldehyde (MDA) and elevated the level of total antioxidant capacity (T-AOC) to weaken oxidative stress caused by Cd exposure in spleen tissue. Moreover, the results showed that Tre significantly suppressed Cd-induced the nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) and up-regulated the protein expression of nuclear Nrf2. Thirdly, Tre remarkably reduced the protein expression of sequestosome 1 (p62/SQSTM1) and microtubule-associated protein light chain 3II (LC-3II) to restore autophagy inhibition induced by Cd exposure. Finally, the results of TUNEL and the expression of apoptosis marker proteins showed that Tre significantly inhibited Cd-induced apoptosis in spleen tissue to exert its protective effects. In summary, the results indicated that Tre modulated Nrf2 signaling pathway, which interacted with apoptosis and autophagy to against Cd-induced spleen injury, providing potential therapeutic strategies for the prevention and treatment of Cd-related immune system diseases.

Nrf2-regulated miR-380-3p Blocks the Translation of Sp3 Protein and Its Mediation of Paraquat-Induced Toxicity in Mouse Neuroblastoma N2a Cells

Laboratorial and epidemiological research has established a relationship between paraquat (PQ) exposure and a risk for Parkinson's disease. Previously, we have investigated the effects of nuclear factor erythroid 2 related factor 2 (Nrf2) and microRNAs in PQ-induced neurotoxicity, addressing the function of miR-380-3p, a microRNA dysregulated by PQ, as well as Nrf2 deficiency. Nrf2 is known to mediate the expression of a variety of genes, including noncoding genes. By chromatin immunoprecipitation, we identified the relationship between Nrf2 and miR-380-3p in transcriptional regulation. qRT-PCR, Western blots, and dual-luciferase reporter gene assay showed that miR-380-3p blocked the translation of the transcription factor specificity protein-3 (Sp3) in the absence of degradation of Sp3 mRNA. Results based on cell counting analysis, annexin v-fluorescein isothiocyanate/propidium iodide double-staining assay, and propidium iodide staining showed that overexpression of miR-380-3p inhibited cell proliferation, increased the apoptotic rate, induced cell cycle arrest, and intensified the toxicity of PQ in mouse neuroblastoma (N2a [Neuro2a]) cells. Knockdown of Sp3 inhibited cell proliferation and eclipsed the alterations induced by miR-380-3p in cell proliferation. Two mediators of apoptosis and cell cycle identified in previous studies as Sp3-regulated, namely cyclin-dependent kinase inhibitor 1 (p21) and calmodulin (CaM), were dysregulated by PQ, but not Sp3 deficiency. In conclusion, Nrf2-regulated miR-380-3p inhibited cell proliferation and enhanced the PQ-induced toxicity in N2a cells potentially by blocking the translation Sp3 mRNA. We conclude that CaM and p21 were involved in PQ-induced toxicity.

"Let my liver rather heat with wine" - a review of hepatic fibrosis pathophysiology and emerging therapeutics

Cirrhosis is characterized by extensive hepatic fibrosis, and it is the 14th leading cause of death worldwide. Numerous contributing conditions have been implicated in its development, including infectious etiologies, medication overdose or adverse effects, ingestible toxins, autoimmunity, hemochromatosis, Wilson’s disease and primary biliary cholangitis to list a few. It is associated with portal hypertension and its stigmata (varices, ascites, hepatic encephalopathy, combined coagulopathy and thrombophilia), and it is a major risk factor for hepatocellular carcinoma. Currently, orthotopic liver transplantation has been the only curative modality to treat cirrhosis, and the scarcity of donors results in many people waiting years for a transplant. Identification of novel targets for pharmacologic therapy through elucidation of key mechanistic components to induce fibrosis reversal is the subject of intense research. Development of robust models of hepatic fibrosis to faithfully characterize the interplay between activated hepatic stellate cells (the principal fibrogenic contributor to fibrosis initiation and perpetuation), hepatocytes and extracellular matrix components has the potential to identify critical components and mechanisms that can be exploited for targeted treatment. In this review, we will highlight key cellular pathways involved in the pathophysiology of fibrosis from extracellular ligands, effectors and receptors, to nuclear receptors, epigenetic mechanisms, energy homeostasis and cytokines. Further, molecular pathways of hepatic stellate cell deactivation are discussed, including apoptosis, senescence and reversal or transdifferentiation to an inactivated state resembling quiescence. Lastly, clinical evidence of fibrosis reversal induced by biologics and small molecules is summarized, current compounds under clinical trials are described and efforts for treatment of hepatic fibrosis with mesenchymal stem cells are highlighted. An enhanced understanding of the rich tapestry of cellular processes identified in the initiation, perpetuation and resolution of hepatic fibrosis, driven principally through phenotypic switching of hepatic stellate cells, should lead to a breakthrough in potential therapeutic modalities.

miR-455-3p Alleviates Hepatic Stellate Cell Activation and Liver Fibrosis by Suppressing HSF1 Expression

Liver fibrosis is a common pathological process of end-stage liver diseases. However, the role of microRNA (miRNA) in liver fibrosis is poorly understood. The activated hepatic stellate cells (HSCs) are the major source of fibrogenic cells and play a central role in liver fibrosis. In this study, we investigated the differential expression of miRNAs in resting and transforming growth factor β1 (TGF-β1) activated HSCs by microarray analysis and found that miR-455-3p was significantly downregulated during HSCs activation. In addition, the reduction of miR-455-3p was correlated with liver fibrosis in mice with carbon tetrachloride (CCl₄), bile duct ligation (BDL), and high-fat diet (HFD)-induced liver fibrosis. Our functional analyses demonstrated that miR-455-3p inhibited expression of profibrotic markers and cell proliferation in HSCs in vitro. Moreover, miR-455-3p regulated heat shock factor 1 (HSF1) expression by binding to the 3′ UTR of its mRNA directly. Overexpression of HSF1 facilitated HSCs activation and proliferation by promoting heat shock protein 47 (Hsp47) expression, leading to activation of the TGF-β/Smad4 signaling pathway. To explore the clinical potential of miR-455-3p, we injected ago-miR-455-3p into mice with CCl₄-, BDL-, and HFD-induced hepatic fibrosis in vivo. The overexpression of miR-455-3p suppressed HSF1 expression and reduced fibrosis marker expression, which resulted in alleviated liver fibrosis in mice. In conclusion, our present study suggests that miR-455-3p inhibits the activation of HSCs through targeting HSF1 involved in the Hsp47/TGF-β/Smad4 signaling pathway. Therefore, miR-455-3p might be a promising therapeutic target for liver fibrosis.

METTL3/m6A/miRNA-873-5p Attenuated Oxidative Stress and Apoptosis in Colistin-Induced Kidney Injury by Modulating Keap1/Nrf2 Pathway

Nephrotoxicity of colistin is the major factor limiting its clinical application. However, the exact mechanism of colistin-induced nephrotoxicity is still elusive. N⁶-Methyladenosine (m⁶A) modification has been implicated in many biological processes, however, its role in colistin-induced nephrotoxicity needs to be elucidated. Mouse renal tubular epithelial cells (mRTECs) were treated with 200 μM colistin with or without METTL3 overexpression. Cells injury, m⁶A assay, oxidative stress and apoptosis were examined. Levels of m⁶A are decreased after colistin treatment in mRTECs. METTL3 is the major factor involved in abnormal m⁶A modification. METTL3 overexpression plays a protective role against colistin-induced oxidative stress and apoptosis. Moreover, METTL3 interacts with the microprocessor protein DGCR8 and positively modulates miR-873-5p mature process in an m⁶A-dependent manner. Further experiments show that miR-873-5p could regulate Keap1-Nrf2 pathway against colistin-induced oxidative stress and apoptosis. These studies revealed an important role of METTL3/m⁶A in colistin-induced nephrotoxicity and provide a new insight on m⁶A modification in drug induced toxicity.

MicroRNA‑200a suppresses migration and invasion and enhances the radiosensitivity of NSCLC cells by inhibiting the HGF/c‑Met signaling pathway

Hepatocyte growth factor (HGF), an activator of the c‑Met signaling pathway, is involved in tumor invasiveness, metastasis and radiotherapy resistance. In the present study, a novel HGF regulatory pathway in lung cancer involving micro-RNAs (miRNAs/miR) is described. Immunohistochemical staining and western blot analyses demonstrated that HGF was upregulated and associated with miR‑200a downregulation in non‑small cell lung cancer (NSCLC) samples compared with normal lung tissues. The association between HGF and miR‑200a was associated with the degree of tumor malignancy and cell migration and invasion. miR‑200a negatively regulated HGF expression by targeting the 3'‑untranslated region of the HGF mRNA. miR‑200a overexpression induced HGF downregulation, decreased NSCLC cell migration and invasion, promoted apoptosis, and decreased cell survival in A549 and H1299 cells in response to ionizing radiation. The present results revealed a previously uncharacterized role of miRNA‑200a in regulating tumor malignancy and radiosensitivity by suppressing HGF expression, a key factor in the HGF/c‑Met pathway.

Ellagic acid ameliorates oxidative stress and insulin resistance in high glucose-treated HepG2 cells via miR-223/keap1-Nrf2 pathway

As a promising new target, miR-233 may regulate oxidative stress by targeting keap1-Nrf2 system to affect the pathological process of liver injury in T2DM. Ellagic acid (EA) is versatile for protecting oxidative stress damage and metabolic disorders. In the present study, we investigated the effect of EA on oxidative stress and insulin resistance in high glucose-induced T2DM HepG2 cells and examined the role of miR-223/keap1-Nrf2 pathway in system. HepG2 cells were incubated in 30 mM of glucose, with or without EA (15 and 30 μM) or metformin (Met, 150 μM) for 12 h. Glucose consumption, phosphorylation of IRS1, Akt and ERK under insulin stimulation, ROS and O₂^- production, MDA level, SOD activity and miR-223 expression, as well as protein levels of keap1, Nrf2, HO-1, SOD1 and SOD2 were analyzed. Furthermore, dual luciferase reporter assay, miR-223 mimic and inhibitor were implemented in cellular studies to explore the possible mechanism. EA upregulated glucose consumption, IRS1, Akt and ERK phosphorylation under insulin stimulation, reduced ROS and O₂^- production and MDA level, and increased SOD activity in high glucose-exposed HepG2 cells. In addition, EA elevated miR-223 expression level, downregulated mRNA and protein levels of keap1, and upregulated Nrf2, HO-1, SOD1 and SOD2 protein levels in this cell model. What's more, dual luciferase reporter assay, miR-223 mimic and inhibitor transfection confirmed that EA activated keap1-Nrf2 system via elevating miR-223. The miR-223, a negative regulator of keap1, represents an attractive therapeutic target in hepatic injury in T2DM. EA ameliorates oxidative stress and insulin resistance via miR-223-mediated keap1-Nrf2 activation in high glucose-induced T2DM HepG2 cells.

Role of microRNAs in alcohol-induced liver disorders and non-alcoholic fatty liver disease

MicroRNAs (miRNAs) are small non-coding RNAs that regulate multiple physiological and pathological functions through the modulation of gene expression at the post-transcriptional level. Accumulating evidence has established a role for miRNAs in the development and pathogenesis of liver disease. Specifically, a large number of studies have assessed the role of miRNAs in alcoholic liver disease (ALD) and non-alcoholic fatty liver disease (NAFLD), two diseases that share common underlying mechanisms and pathological characteristics. The purpose of the current review is to summarize and update the body of literature investigating the role of miRNAs in liver disease. In addition, the potential use of miRNAs as biomarkers and/or therapeutic targets is discussed. Among all miRNAs analyzed, miR-34a, miR-122 and miR-155 are most involved in the pathogenesis of NAFLD. Of note, these three miRNAs have also been implicated in ALD, reinforcing a common disease mechanism between these two entities and the pleiotropic effects of specific miRNAs. Currently, no single miRNA or panel of miRNAs has been identified for the detection of, or staging of ALD or NAFLD. While promising results have been shown in murine models, no therapeutic based-miRNA agents have been developed for use in humans with liver disease.

The Nrf2-Antioxidant Response Element Signaling Pathway Controls Fibrosis and Autoimmunity in Scleroderma

Systemic sclerosis (SSc) is an autoimmune disease with fibrosis of the skin and internal organs and vascular alterations. Dysregulations in the oxidant/antioxidant balance are known to be a major factor in the pathogenesis of the disease. Indeed, reactive oxygen species (ROS) trigger neoepitopes leading to a breach of immune tolerance and autoimmune responses, activate fibroblasts to proliferate and to produce excess of type I collagen. ROS also alter endothelial cells leading to vascular dysfunction. Glutathione (GSH) is the most potent antioxidant system in eukaryotic cells. Numerous studies have reported a defect in GSH in SSc animal models and humans, but the origin of this defect remains unknown. The transcription factor NRF2 is a key player in the antioxidant defense, as it can induce the transcription of antioxidant and cytoprotective genes, including GSH, through its interaction with the antioxidant response elements. In this work, we investigated whether NRF2 could be implicated in the pathogenesis of SSc, and if this pathway could represent a new therapeutic target in this orphan disease with no curative medicine. Skin biopsies from 11 patients and 10 controls were harvested, and skin fibroblasts were extracted. Experimental SSc was induced both in BALB/c and in nrf2^-/- mice by daily intradermal injections of hypochloric acid. In addition, diseased BALB/c mice were treated with an nrf2 agonist, dimethyl fumarate, or placebo. A drop in nrf2 and target genes mRNA levels was observed in skin fibroblasts of SSc patients compared to controls. Moreover, the nrf2 pathway is also downregulated in skins and lungs of SSc mice. In addition, we observed that nrf2^-/- mice have a more severe form of SSc with increased fibrosis and inflammation compared to wild-type SSc mice. Diseased mice treated with the nrf2 agonist dimethyl fumarate (DMF) exhibited reduced fibrosis and immune activation compared to untreated mice. The ex vivo treatment of skin fibroblasts from SSc mice with DMF restores GSH intracellular content, decreases ROS production and cell proliferation. These results suggest that the nrf2 pathway is highly dysregulated in human and SSc mice with deleterious consequences on fibrosis and inflammation and that Nrf2 modulation represents a therapeutic target in SSc.

MicroRNA-942 mediates hepatic stellate cell activation by regulating BAMBI expression in human liver fibrosis

MicroRNA (miRNA)-mediated gene regulation contributes to liver pathophysiology, including hepatic stellate cell (HSC) activation and fibrosis progression. Here, we investigated the role of miR-942 in human liver fibrosis. The expression of miR-942, HSC activation markers, transforming growth factor-beta pseudoreceptor BMP and activin membrane-bound inhibitor (BAMBI), as well as collagen deposition, were investigated in 100 liver specimens from patients with varying degree of hepatitis B virus (HBV)-related fibrosis. Human primary HSCs and the immortalized cell line (LX2 cells) were used for functional studies. We found that miR-942 expression was upregulated in activated HSCs and correlated inversely with BAMBI expression in liver fibrosis progression. Transforming growth factor beta (TGF-β) and lipopolyssacharide (LPS), two major drivers of liver fibrosis and inflammation, induce miR-942 expression in HSCs via Smad2/3 respective NF-κB/p50 binding to the miR-942 promoter. Mechanistically, the induced miR-942 degrades BAMBI mRNA in HSCs, thereby sensitizing the cells for fibrogenic TGF-β signaling and also partly mediates LPS-induced proinflammatory HSC fate. In conclusion, the TGF-β and LPS-induced miR-942 mediates HSC activation through downregulation of BAMBI in human liver fibrosis. Our study provides new insights on the molecular mechanism of HSC activation and fibrosis.

Nrf2 protects stellate cells from Smad-dependent cell activation

Hepatic stellate cells (HSC) orchestrate the deposition of extracellular matrix (ECM) and are the primary effector of liver fibrosis. Several factors, including TGF-β1, PDGF and oxidative stress, have been shown to trigger HSC activation. However, the involvement of cellular defence mechanisms, such as the activation of antioxidant response by Nrf2/Keap1 in the modulation of HSC activation is not known. The aim of this work was to elucidate the role of Nrf2 pathway in HSC trans-differentiation involved in the development of fibrosis. To this end, we repressed Nrf2 and Keap1 expression in HSC with specific siRNAs. We then assessed activation markers, as well as proliferation and migration, in both primary and immortalised human HSCs exposed to Smad inhibitors (SB-431542 hydrate and SB-525334), TGF-β1 and/or PDGF. Our results indicate that knocking down Nrf2 induces HSC activation, as shown by an increase in αSMA-positive cells and by gene expression induction of ECM components (collagens and fibronectin). HSC with reduced Nrf2-levels also showed an increase in migration and a decrease in proliferation. We could also demonstrate that the activation of Nrf2-deficient HSC involves the TGF-β1/Smad pathway, as the activation was successfully inhibited with the two tested Smad inhibitors. Moreover, TGF-β1 elicited a stronger induction of HSC activation markers in Nrf2 deficient cells than in wild type cells. Thus, our data suggest that Nrf2 limits HSCs activation, through the inhibition of the TGF-β1/Smad pathway in HSCs.

MicroRNA-200a induces apoptosis by targeting ZEB2 in alcoholic liver disease

ABSTRAT Alcoholic liver disease (ALD) and its complication continued to be a major health problem throughout the world. Increasing evidence suggests that microRNA (miRNA) that regulate apoptosis, inflammation and lipid metabolism are affected by alcohol in ALD. MiR-200a has emerged as a major regulator in several liver diseases, but its role in ALD has not been elucidated. The aim of this study is to figure out the biological function of miR-200a in ALD and to explore its underlying mechanism. The expression pattern of miR-200a were analyzed in vitro and in vivo, we showed that miR-200a was up-regulated in ALD in AML-12 and primary hepatocyte. We then examined it's effect on cell apoptosis and identified zinc finger E-box binding homeobox 2 (ZEB2; also known as SIP1) as a direct target gene of miR-200a. Furthermore, reintroduction of ZEB2 could reverse the pro-apoptosis of miR-200a on AML-12. Taken together, our study demonstrated that miR-200a regulates the apoptosis of hepatocyte in ALD by directly target ZEB2, both of which could serve as new therapeutic targets for ALD.

Inhibition of autophagy reverses alcohol-induced hepatic stellate cells activation through activation of Nrf2-Keap1-ARE signaling pathway

BACKGROUND

Numerous documents have indicated a critical role of autophagy in alcoholic liver fibrosis (ALF), but few papers have reported its function in hepatic stellate cells (HSCs) activation. The current study aimed to investigate the regulation effect of autophagy in HSCs activation, in further to explore the underlying mechanism involved.

METHODS

HSC-T6 cells were treated with ethanol, 3-MA (autophagy inhibitor) or rapamycin (autophagy inducer), and cells were also transfected with si-Nrf2 or si-Keap1. Moreover, ALF animal model was established and Nrf-2^(-/-), Keap1 ^(-/-) mice were purchased. The level of autophagy, the expression of α-SMA and CoL1A1, and Nrf2 antioxidant response were evaluated in stellate cells and livers.

RESULTS

Ethanol treatment in cultured cells increased autophagy, oxidative stress level and promoted HSCs activation. Inhibition of autophagy reversed alcohol-induced HSCs activation and suppressed HSCs oxidative stress. Nrf2-Keap1-ARE pathway was involved in HSCs activation and oxidative stress regulated by autophagy. In addition, through in vivo study, we found that inhibition of autophagy could alleviate alcoholic fatty liver injury in ALF model mice and Nrf2 signaling was involved in autophagy regulated HSCs activation.

CONCLUSION

These data implicated mechanisms underlying autophagy in regulating the fibrogenic response in HSCs activation.

Hepatic stellate cells as key target in liver fibrosis

Progressive liver fibrosis, induced by chronic viral and metabolic disorders, leads to more than one million deaths annually via development of cirrhosis, although no antifibrotic therapy has been approved to date. Transdifferentiation (or "activation") of hepatic stellate cells is the major cellular source of matrix protein-secreting myofibroblasts, the major driver of liver fibrogenesis. Paracrine signals from injured epithelial cells, fibrotic tissue microenvironment, immune and systemic metabolic dysregulation, enteric dysbiosis, and hepatitis viral products can directly or indirectly induce stellate cell activation. Dysregulated intracellular signaling, epigenetic changes, and cellular stress response represent candidate targets to deactivate stellate cells by inducing reversion to inactivated state, cellular senescence, apoptosis, and/or clearance by immune cells. Cell type- and target-specific pharmacological intervention to therapeutically induce the deactivation will enable more effective and less toxic precision antifibrotic therapies.

MicroRNA-200a activates Nrf2 signaling to protect osteoblasts from dexamethasone

Treatment with dexamethasone in human osteoblasts leads to oxidative stress and cell injures. NF-E2-related factor 2 (Nrf2) is a key anti-oxidant signaling. We want to induce Nrf2 activation via microRNA-mediated silencing its suppressor Keap1. Our results show that microRNA-200a ("miR-200a") expression depleted Keap1, causing Nrf2 protein stabilization in OB-6 osteoblastic cells. Reversely, the miR-200a anti-sense led to Keap1 upregulation and Nrf2 degradation. miR-200a expression activated Nrf2 signaling, which inhibited dexamethasone-induced reactive oxygen species production and OB-6 cell death/apoptosis. Keap1 shRNA also activated Nrf2 and protected OB-6 cells from dexamethasone. Importantly, miR-200a was in-effective in Keap1-silenced (by shRNA) OB-6 cells. In the primary human osteoblasts, Keap1 silence by targeted-shRNA or miR-200a protected cells from dexamethasone. Significantly, miR-200a level was decreased in necrotic femoral head tissues, which was correlated with Keap1 mRNA upregulation. Together, miR-200a expression activates Nrf2 signaling and protects human osteoblasts from dexamethasone.

Nrf2 activation is required for curcumin to induce lipocyte phenotype in hepatic stellate cells

Hepatic fibrosis is a reversible scarring response that commonly occurs with chronic liver injury. During hepatic fibrogenesis, the major effector hepatic stellate cells (HSCs) become activated, featured by disappeared intracellular lipid droplets, decreased retinoid storage, and dysregulated expression of genes associated with lipid and retinoid metabolism. Compelling evidence suggested that recovery of retinoid droplets could inhibit HSC activation, while the precise molecular basis underlying the phenotypical switch still remained unclear. In this study, curcumin increased the abundance of lipid droplets and content of triglyceride in activated HSCs. In addition, curcumin could concentration-dependently regulate genes associated with lipid and retinoid metabolism. Further, consistent results were obtained from in vivo experiments. Curcumin increased Nrf2 expression and nuclear translocation, and its binding activity to DNA, which might be associated with suppression of Kelch-like ECH-associated protein 1 in HSCs. Of interest was that Nrf2 overexpression plasmids, in contract to Nrf2 siRNA, strengthened the effect of curcumin on induction of lipocyte phenotype. In in vivo system, Nrf2 knockdown mediated by Nrf2 shRNA lentivirus not only accelerated the lipid degradation in HSCs but also promoted the progression of CCl₄-induced hepatic fibrosis in mice. Noteworthily, Nrf2 knockdown abolished the protective effect of curcumin. In conclusion, curcumin could induce lipocyte phenotype of activated HSCs via activating Nrf2. Nrf2 could be a target molecule for antifibrotic strategy.

microRNA-455 targets cullin 3 to activate Nrf2 signaling and protect human osteoblasts from hydrogen peroxide

Over-production of hydrogen peroxide (H₂O₂) will lead to human osteoblast dysfunction and apoptosis, causing progression of osteoporosis and osteonecrosis. NF-E2-related factor 2 (Nrf2) is a well-characterized anti-oxidant signaling. Cullin 3 (Cul3) ubiquitin E3 ligase dictates Nrf2 degradation. We demonstrate that microRNA-455 ("miR-455") is a putative Cul3-targeting microRNA. Forced-expression of miR-455 in both hFOB1. 19 osteoblast cell line and primary human osteoblasts induced Cul3 degradation and Nrf2 protein stabilization, which led to subsequent transcription of ARE (anti-oxidant response element)-dependent genes (NQO1, HO1 and GCLC). Cul3 silencing, by expressing miR-455 or targeted-shRNA, protected human osteoblasts from H₂O₂. Reversely, miR-455 anti-sense caused Cul3 accumulation and Nrf2 degradation, which exacerbated H₂O₂ damages in hFOB1. 19 cells. Moreover, forced over-expression of Cul3 in hFOB1. 19 cells silenced Nrf2 and sensitized H₂O₂. Together, we propose that miR-455 activated Nrf2 signaling and protected human osteoblasts from oxidative stress possibly via targeting Cul3.

The roles of microRNA families in hepatic fibrosis

When hepatocytes are damaged severely, a variety of signaling pathways will be triggered by inflammatory factors and cytokines involving in the process of hepatic fibrosis. The microRNA (miRNA) family consists of several miRNAs which have the potential for synergistic regulation of these signaling pathways. However, it is poor to understand the roles of miRNA family as a whole in hepatic fibrosis. Increasing studies have suggested several miRNA families are related with activation of hepatic stellate cells and hepatic fibrosis through cooperatively regulating certain signaling pathways. During the process of hepatic fibrosis, miR-29 family primarily induces cell apoptosis by modulating phosphatidylinositol 3-kinase/AKT signaling pathway and regulates extracellular matrix accumulation. miR-34 family promotes the progression of hepatic fibrosis by inducing activation of hepatic stellate cells, while miR-378 family suppresses the process in Glis dependent manner. miR-15 family mainly promotes cell proliferation and induces apoptosis. The miR-199 family and miR-200 family are responsible for extracellular matrix deposition and the release of pro-fibrotic cytokines. These miRNA family members play pro-fibrotic or anti-fibrotic roles by targeting genes collectively or respectively which involve in hepatic fibrosis related signaling pathways and hepatic stellate cell activation. Thus, good understandings of molecular mechanisms which are based on miRNA families may provide new ideas for the molecular targeted therapy of hepatic fibrosis in the future.

Pro-fibrotic compounds induce stellate cell activation, ECM-remodelling and Nrf2 activation in a human 3D-multicellular model of liver fibrosis

Background & Aims

Currently most liver fibrosis research is performed in vivo, since suitable alternative in vitro systems which are able to recapitulate the cellular events leading to liver fibrosis are lacking. Here we aimed at generating a system containing cells representing the three key players of liver fibrosis (hepatocyte, Kupffer cells and stellate cells) and assess their response to pro-fibrotic compounds such as TGF-β1, methotrexate (MTX) and thioacetamide (TAA).

Methods

Human cell lines representing hepatocytes (HepaRG), Kupffer cell (THP-1 macrophages) and stellate cells (hTERT-HSC) were co-cultured using the InSphero hanging drop technology to generate scaffold-free 3D microtissues, that were treated with pro-fibrotic compounds (TGF-β1, MTX, TAA) for up to 14 days. The response of the microtissues was evaluated by determining the expression of cytokines (TNF-α, TGF-β1 and IL6), the deposition and secretion of ECM proteins and induction of gene expression of fibrosis biomarkers (e.g. αSMA). Induction of Nrf2 and Keap1, as key player of defence mechanism, was also evaluated.

Results

We could demonstrate that the multicellular 3D microtissue cultures could be maintained in a non-activated status, based on the low expression levels of activation markers. Macrophages were activated by stimulation with LPS and hTERT-HSC showed activation by TGF-β1. In addition, MTX and TAA elicited a fibrotic phenotype, as assessed by gene-expression and protein-deposition of ECM proteins such as collagens and fibronectin. An involvement of the antioxidant pathway upon stimulation with pro-fibrotic compounds was also observed.

Conclusion

Here, for the first time, we demonstrate the in vitro recapitulation of key molecular and cellular events leading to liver fibrosis: hepatocellular injury, antioxidant defence response, activation of Kupffer cells and activation of HSC leading to deposition of ECM.

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.