The roles of lncRNA in hepatic fibrosis

LncRNA MALAT1 Knockdown Alleviates Fibrogenic Response in Human Endometrial Stromal Cells Via the miR-22-3p/TGFβR1/Smad2/3 Pathway

Intrauterine adhesion (IUA) resulting from irreversible fibrotic repair of endometrium is the main cause of secondary infertility in women, and current therapeutic approaches to IUA are limited. Increasing evidence has suggested the important role of competitive endogenous RNA (ceRNA) in IUA pathologies. This study aimed to investigate the long noncoding RNA (lncRNA) metastasis associated lung adenocarcinoma transcript 1 (MALAT1)-associated ceRNA in IUA development. We harvested endometrial tissues from patients with or without IUA and extracted endometrial stromal cells (ESCs) from normal endometrial tissues. Transforming growth factor β1 (TGF-β1) was used to induce fibrosis in ESCs. The expression of transforming growth factor β receptor 1 (TGFβR1), α-smooth muscle actin, phosphorylated suppressor of mother against decapentaplegic (p-Smad)2/3, collagen type I alpha 1, MALAT1, and microRNA (miR)-22-3p in endometrial tissues and ESCs was measured by reverse transcription quantitative polymerase chain reaction (RT-qPCR) or western blotting. Pearson's correlation analysis was conducted to assess the correlation between miR-22-3p expression or TGFβR1 and MALAT1 expression in endometrial tissues. The expression of TGFβR1 in ESCs was also evaluated by immunofluorescence staining. The location of MALAT1 was examined by fluorescence in situ hybridization. Luciferase reporter assays were performed to verify the binding relationship between MALAT1 or TGFβR1 and miR-22-3p. Cell viability was assessed via cell counting kit-8 assays. Our findings revealed that lncRNA MALAT1 and TGFβR1 were upregulated while miR-22-3p was downregulated in IUA endometrial tissues or TGF-β1-stimulated ESCs, and lncRNA MALAT1 expression was negatively correlated with miR-22-3p expression while being positively correlated with TGFβR1 expression in IUA endometrial tissues. Additionally, lncRNA MALAT1 was mainly located in the cytoplasm of ESCs and directly targeted miR-22-3p to regulate TGFβR1 expression. Moreover, knockdown of lncRNA MALAT1 exerted anti-fibrotic effects on ESCs by targeting miR-22-3p, and miR-22-3p overexpression inhibited the fibrosis of ESCs by binding to TGFβR1 3'untranslated region. Collectively, lncRNA MALAT1 promotes endometrial fibrosis by sponging miR-22-3p to regulate TGFβR1 and Smad2/3, and inhibition of MALAT1 may represent a promising therapeutic option for suppressing endometrial fibrosis.

Long non-coding RNA H19 mediates the miR-29b/transforming growth factor-β1/Drosophila mothers against decapentaplegic 3 signalling pathway to promote bladder fibrosis in diabetic rats

PURPOSE

Diabetic bladder fibrosis is a common comorbidity. Altered expression of some long non-coding RNAs (LncRNAs) has been associated with bladder fibrosis. LncRNA H19 has been reported to regulate bladder cancer through miR-29b. However, the action mechanism of LncRNA H19 in bladder fibrosis is unclear.

METHODS

In vitro, human bladder smooth muscle cells (HBSMCs) were cultured with transforming growth factor-β1 (TGF-β1) for 48 h to construct cell model of bladder fibrosis. HBSMCs were then transfected with si-LncRNA H19, si-NC, miR-29b-mimic, mimic-NC, or miR-29b-inhibitor. In vivo, Sprague-Dawley (SD) rats were given a high-sucrose-high-fat (HSHF) diet for 4 weeks and injected with streptozotocin (STZ, 50 mg/kg) to induce bladder fibrosis model in diabetic rats, followed by injection of lentiviral particles knocking down LncRNA H19 expression, empty vector, or miR-29b-inhibitor, respectively.

RESULTS

LncRNA H19 was up-regulated in TGF-β1-induced HBSMC fibrosis and STZ-induced diabetic rat bladder fibrosis, whereas miR-29b was down-regulated. si-LncRNA H19 reduced blood glucose levels and improved histopathological damage of bladder tissue in rats. In addition, si-LncRNA H19 or miR-29b-mimic increased the expression of E-cadherin, but decreased the expression of N-cadherin, vimentin, fibronectin (FN) in bladder tissues, and HBSMCs. si-LncRNA H19 reduced TGF-β1/p-drosophila mothers against decapentaplegic 3 (Smad3) protein in HBSMCs and in rat bladder tissues, while miR-29b-inhibitor reversed the effect of si-LncRNA H19.

CONCLUSION

This study indicated that LncRNA H19 may inhibit bladder fibrosis in diabetic rats by targeting miR-29b via the TGF-β1/Smad3 signalling pathway.

The impact of ICOSL/ICOS pathway-regulated long non-coding RNAs on liver fibrosis in mice infected with Schistosoma japonicum

BACKGROUND

The primary pathogenic mechanism of schistosomiasis-associated liver fibrosis involves the deposition of schistosome eggs, leading to the formation of liver egg granulomas and subsequent liver fibrosis. Hepatic stellate cells are abnormally activated, resulting in excessive collagen deposition and fibrosis development. While specific long non-coding RNAs (lncRNAs) have been associated with fibrotic processes, their roles in schistosomiasis-associated liver fibrosis remain unclear.

METHODS

Our previous research indicated that downregulating the ICOSL/ICOS could partially alleviate liver fibrosis. In this study, we established a schistosomiasis infection model in C57BL/6 and ICOSL knockout (KO) mice, and the liver pathology changes were observed at various weeks postinfection (wpi) using hematoxylin and eosin and Masson's trichrome staining. Within the first 4 wpi, no significant liver abnormalities were observed. However, mice exhibited evident egg granulomas and fibrosis in their livers at 7 wpi. Notably, ICOSL-KO mice had significantly smaller pathological variations compared with simultaneously infected C57BL/6 mice. To investigate the impact of lncRNAs on schistosomiasis-associated liver fibrosis, quantitative real-time polymerase chain reaction (RT-qPCR) was used to monitor the dynamic changes of lncRNAs in hepatic stellate cells of infected mice.

RESULTS

The results demonstrated that lncRNA-H19, -MALAT1, -PVT1, -P21 and -GAS5 all participated in liver fibrosis formation after schistosome infection. In addition, ICOSL-KO mice exhibited significantly inhibited expression of lncRNA-H19, -MALAT1 and -PVT1 after 7 wpi. In contrast, they showed enhanced expression of lncRNA-P21 and -GAS5 compared with C57BL/6 mice, influencing liver fibrosis development. Furthermore, small interfering RNA transfection (siRNA) in JS-1 cells in vitro confirmed that lncRNA-H19, -MALAT1, and -PVT1 promoted liver fibrosis, whereas lncRNA-P21 and -GAS5 had the opposite effect on key fibrotic molecules, including α- smooth muscle actin and collagen I expression.

CONCLUSIONS

This study uncovers that ICOSL/ICOS may play a role in activating hepatic stellate cells and promoting liver fibrosis in mice infected with Schistosoma japonicum by dynamically regulating the expression of specific lncRNAs. These findings offer potential therapeutic targets for schistosomiasis-associated liver fibrosis.

Identification of functional genes in liver fibrosis based on bioinformatics analysis of a lncRNA-mediated ceRNA network

BACKGROUND

Liver fibrosis is a major global healths problem; nevertheless, its molecular mechanism are not completely clear. This study aimed to build a lncRNA-miRNA-mRNA network, identify potentially related lncRNAs, and explore the pathogenesis of liver fibrosis.

MATERIALS AND METHODS

We used the Gene Expression Omnibus databases and bioinformatics analysis to identify differentially expressed genes (DEGs) between liver fibrosis and normal tissues. The ceRNA network was constructed according to the interactions between DElncRNA, miRNA, and DEmRNA. Then, these DEGs were identified using functional enrichment analysis, and a protein-protein interaction (PPI) network was established. The critical lncRNAs were verified using the quantitative real-time polymerase chain reaction (qRT-PCR).

RESULTS

The ceRNA network was composed of three lncRNAs, five miRNAs, and 93 mRNAs. Gene Ontology functional enrichment analysis revealed significant enhancement in cell components, molecular function, and biological process. Kyoto Encyclopedia of Genes and Genomes pathway analysis revealed pathways associated with transcriptional misregulation in cancer, including the Rap1 signaling pathway, proteoglycans in cancer, mineral absorption, HTLV-l infection, and central carbon metabolism in cancer. According to the PPI network and the GSE84044 database, seven hub genes associated with liver fibrosis were identified. In addition, qRT-PCR revealed that lncRNA AC100861 (lncRNA TNFRSF10A-DT) was explicitly decreased in liver fibrosis tissues and activated hepatic stellate cells.

CONCLUSIONS

In summary, this study preliminarily found that lncRNA TNFRSF10A-DT may be a biomarker for the diagnosis and outcome of liver fibrosis. We uncovered a novel lncRNA-mediated ceRNA regulatory mechanism in the pathogenesis of liver fibrosis.

TUG1 protects against ferroptosis of hepatic stellate cells by upregulating PDK4-mediated glycolysis

The induction of ferroptosis in hepatic stellate cells (HSCs) has shown promise in reversing liver fibrosis. And ferroptosis has been confirmed to be associated with glycolysis. The objective of this study is to determine whether ferroptosis inhibition in HSCs, induced by elevation of recombinant pyruvate dehydrogenase kinase isozyme 4 (PDK4)-mediated glycolysis, could mediate the pathogenesis of liver fibrosis. Liver fibrosis was induced using CCl4, the level of which was assessed through histochemical staining. Lentivirus was used to modulate the expression of specific genes. And underlying mechanisms were explored using primary HSCs extracted from normal mice. The results confirmed that Taurine up-regulated gene 1 (TUG1) expression was upregulated in liver fibrotic tissues and HSCs, showing a positive correlation with fibrosis. In addition, TUG1 attenuated ferroptosis in HSCs by promoting PDK4-mediated glycolysis, thereby promoting the progression of liver fibrosis. Moreover, TUG1 was observed to impact HSCs activation, exacerbating liver fibrosis to some extent. In conclusion, our study revealed that TUG1 expression was elevated in mouse models of liver fibrosis and activated HSCs, which inhibited ferroptosis in HSCs through PDK4-mediated glycolysis. This finding may open up a new therapeutic strategy for liver fibrosis.

Transcriptional regulation of Glis2 in hepatic fibrosis

The role of Gli-similar 2 (Glis2) in hepatic fibrosis (HF) is controversial. In this study, we focused on the functional and molecular mechanisms involved in the Glis2-mediated activation of hepatic stellate cells (HSCs)-a milestone event leading to HF. The expression levels of Glis2 mRNA and protein were significantly decreased in the liver tissues of patients with severe HF and in mouse fibrotic liver tissues as well as HSCs activated by TGFβ1. Functional studies indicated that upregulated Glis2 significantly inhibited HSC activation and alleviated BDL-induced HF in mice. Downregulation of Glis2 was found to correlate significantly with DNA methylation of the Glis2 promoter mediated by methyltransferase 1 (DNMT1), which restricted the binding of hepatic nuclear factor 1-α (HNF1-α), a liver-specific transcription factor, to Glis2 promoters. In addition, the enrichment of DNMT1 in the Glis2 promoter region was mediated by metastasis-associated lung adenocarcinoma transcriptor-1 (MALAT1) lncRNA, leading to transcriptional silencing of Glis2 and activation of HSCs. In conclusion, our findings reveal that the upregulation of Glis2 can maintain the resting state of HSCs. The decreased expression of Glis2 under pathological conditions may lead to the occurrence and development of HF with the expression silencing of DNA methylation mediated by MALAT1 and DNMT1.

Huangqi Decoction, a compound Chinese herbal medicine, inhibits the proliferation and activation of hepatic stellate cells by regulating the long noncoding RNA-C18orf26-1/microRNA-663a/transforming growth factor-β axis

OBJECTIVE

Huangqi Decoction (HQD), a classical traditional Chinese medicine formula, has been used as a valid treatment for alleviating liver fibrosis; however, the underlying molecular mechanism is still unknown. Although our previous studies showed that microRNA-663a (miR-663a) suppresses the proliferation and activation of hepatic stellate cells (HSCs) and the transforming growth factor-β/small mothers against decapentaplegic (TGF-β/Smad) pathway, whether long noncoding RNAs (lncRNAs) are involved in HSC activation via the miR-663a/TGF-β/Smad signaling pathway has not yet reported. The present study aimed to investigate the roles of lncRNA lnc-C18orf26-1 in the activation of HSCs and the mechanism by which HQD inhibits hepatic fibrosis.

METHODS

The expression levels of lnc-C18orf26-1, miR-663a and related genes were measured by quantitative reverse transcription-polymerase chain reaction. HSCs were transfected with the miR-663a mimic or inhibitor and lnc-C18orf26-1 small interfering RNAs. The water-soluble tetrazolium salt-1 assay was used to assess the proliferation rate of HSCs. Changes in lncRNA expression were evaluated in miR-663a-overexpressing HSCs by using microarray to identify miR-663a-regulated lncRNAs. RNA hybrid was used to predict the potential miR-663a binding sites on lncRNAs. Luciferase reporter assays further confirmed the interaction between miR-663a and the lncRNA. The expression levels of collagen α-2(I) chain (COL1A2), α-smooth muscle actin (α-SMA) and TGF-β/Smad signaling pathway-related proteins were determined using Western blotting.

RESULTS

Lnc-C18orf26-1 was upregulated in TGF-β1-activated HSCs and competitively bound to miR-663a. Knockdown of lnc-C18orf26-1 inhibited HSC proliferation and activation, downregulated TGF-β1-stimulated α-SMA and COL1A2 expression, and inhibited the TGF-β1/Smad signaling pathway. HQD suppressed the proliferation and activation of HSCs. HQD increased miR-663a expression and decreased lnc-C18orf26-1 expression in HSCs. Further studies showed that HQD inhibited the expression of COL1A2, α-SMA, TGF-β1, TGF-β type I receptor (TGF-βRI) and phosphorylated Smad2 (p-Smad2) in HSCs, and these effects were reversed by miR-663a inhibitor treatment.

CONCLUSION

Our study identified lnc-C18orf26-1 and miR-663a as promising therapeutic targets for hepatic fibrosis. HQD inhibits HSC proliferation and activation at least partially by regulating the lnc-C18orf26-1/miR-663a/TGF-β1/TGF-βRI/p-Smad2 axis.

Whole-transcriptome sequencing revealed differentially expressed mRNAs and non-coding RNAs played crucial roles in NiONPs-induced liver fibrosis

Nickel oxide nanoparticles (NiONPs) induced liver fibrosis, while its mechanisms associated with transcriptome remained unclear. This study aimed to investigate the roles of differentially expressed (DE) messenger RNAs (mRNAs) and non-coding RNAs (ncRNAs) in NiONPs-induced liver fibrosis, and further confirm whether JNK/c-Jun pathway enriched by the DE RNAs was involved in the regulation of the disease. A liver fibrosis rat model was established by intratracheal perfusion of NiONPs twice a week for 9 weeks. Whole-transcriptome sequencing was applied to obtain expression profiles of mRNAs, long non-coding RNAs (lncRNAs), microRNAs (miRNAs), and circular RNAs (circRNAs) in the model rat and control liver tissues. Comparing the RNA expression profiles of the model and control liver tissues, we identified 324 DE mRNAs, 129 DE lncRNAs, 24 DE miRNAs and 33 DE circRNAs, and the potential interactions among them were revealed by constructing two co-expression networks, including lncRNA-miRNA-mRNA and circRNA-miRNA-mRNA networks. Using RT-qPCR, we verified the sequencing results of some RNAs in the networks and obtained similar expression profiles, indicating our sequencing results were reliable and referable. Through Gene Ontology (GO) annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, we predicted the biological functions and signaling pathways potentially related to NiONPs-induced liver fibrosis, such as "positive regulation of JNK cascade", "inflammatory response", "transcription factor binding", and MAPK, Wnt, PI3K-Akt signaling pathways. JNK/c-Jun pathway, a subclass of MAPK signal, was selected for further investigation because it was significantly enriched by fibrosis-related DE genes and activated in animal models. In vitro, we detected the cytotoxicity of NiONPs on LX-2 cells and treated the cells with 5 μg/ml NiONPs for 12 h. The results showed NiONPs induced the up-regulated protein expression of fibrotic factors collagen-1a1 (Col-1a1) and matrix metalloproteinas2 (MMP2) and JNK/c-Jun pathway activation. While these effects were reversed after JNK/c-Jun pathway was blocked by SP600125 (JNK pathway inhibitor), indicating the pathway was involved in NiONPs-induced excessive collagen formation. In conclusion, our results revealed the DE mRNAs and ncRNAs played crucial roles in NiONPs-induced liver fibrosis, and JNK/c-Jun pathway mediated the development of the disease.

Salvianolic acid B suppresses hepatic stellate cell activation and liver fibrosis by inhibiting the NF-κB signaling pathway via miR-6499-3p/LncRNA-ROR

BACKGROUND

Long non-coding RNA (LncRNAs) have been reported to play an important role in liver fibrosis and are closely associated with hepatic stellate cell (HSC) activation. We previously found that salvianolic acid B (Sal B) improves liver fibrosis by regulating the NF-κB signaling pathway. However, whether the LncRNA, regulator of reprogramming (LncRNA-ROR) plays a role in Sal B-mediated anti-fibrosis effects via the NF-κB signaling pathway remain unclear.

PURPOSE

This study aimed to evaluate the effects of Sal B on HSC activation and liver fibrosis and investigate its mechanism from the perspective of LncRNA-ROR-mediated NF-κB signaling pathways.

METHODS

LX-2 and T6 cell lines were cultured. Animal models of liver fibrosis were established using CCl4 in male BALB/c mice. Primary HSCs were isolated from mice and cultured. Serum biochemical and liver histological analyses were performed to evaluate the effects of Sal B on liver fibrosis. The index of HSC activation and the expression of LncRNA-ROR, microRNAs (miRNAs), and inflammatory factors were determined by quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR) or immunofluorescence staining. Cell proliferation was measured by a Cell Counting Kit-8 (CCK-8). NF-κB signaling-associated protein levels were assessed using western blotting or immunofluorescence staining. A luciferase reporter assay was used to detect transcription activity.

RESULTS

In this study, a lower level of LncRNA-ROR was found during Sal B attenuating HSC activation in HSCs. Mechanistically, Sal B impeded the NF-κB signaling pathway to inhibit HSC proliferation and activation by downregulating LncRNA-ROR. Additionally, Sal B upregulated miR-6499-3p to target LncRNA-ROR for degradation. Functionally, Sal B treatment ameliorated CCl4-induced liver fibrosis in mice by inhibiting HSC activation.

CONCLUSION

Sal B suppresses HSC activation and liver fibrosis via regulation of miR-6499-3p/LncRNA-ROR-mediated NF-κB signaling pathway. These results reveal a new molecular mechanism of Sal B on liver fibrosis from the insight of LncRNAs.

mRNA and lncRNA expression profiles of liver tissues in children with biliary atresia

Progressive liver fibrosis is the most common phenotype in biliary atresia (BA). A number of pathways contribute to the fibrosis process so comprehensive understanding the mechanisms of liver fibrosis in BA will pave the way to improve patient's outcome after operation. In this study, the differentially expressed profiles of mRNAs and long non-coding RNAs from BA and choledochal cyst (CC) liver tissues were investigated and analyzed, which may provide potential clues to clarify hepatofibrosis mechanism in BA. A total of two BA and two CC liver tissue specimens were collected, the expression level of mRNAs and lncRNAs was detected by RNA sequencing. Differentially expressed mRNAs (DEmRNAs) were functionally annotated and protein-protein interaction networks (PPI) was established to predict the biological roles and interactive relationships. Differentially expressed lncRNAs (DElncRNAs) nearby targeted DEmRNA network and DElncRNA-DEmRNA co-expression network were constructed to further explore the roles of DElncRNAs in BA pathogenesis. The expression profiles of significant DEmRNAs were validated in Gene Expression Omnibus database. A total of 2,086 DEmRNAs and 184 DElncRNAs between BA and CC liver tissues were obtained. DEmRNAs were enriched in 521 Gene Ontology terms and 71 Kyoto Encyclopedia of Genes and Genomes terms which were mainly biological processes and metabolic pathways related to immune response and inflammatory response. A total of five hub proteins (TYRO protein tyrosine kinase binding protein, C-X-C motif chemokine ligand 8, pleckstrin, Toll-like receptor 8 and C-C motif chemokine receptor 5) were found in the PPI networks. A total of 31 DElncRNA-nearby-targeted DEmRNA pairs and 2,337 DElncRNA-DEmRNA co-expression pairs were obtained. The expression of DEmRNAs obtained from RNA sequencing were verified in GSE46960 dataset, generally. The present study identified key genes and lncRNAs participated in BA associated liver fibrosis, which may present a new avenue for understanding the patho-mechanism for hepatic fibrosis in BA.

Function of the Long Noncoding RNAs in Hepatocellular Carcinoma: Classification, Molecular Mechanisms, and Significant Therapeutic Potentials

Hepatocellular carcinoma (HCC) is the most common and serious type of primary liver cancer. HCC patients have a high death rate and poor prognosis due to the lack of clear signs and inadequate treatment interventions. However, the molecular pathways that underpin HCC pathogenesis remain unclear. Long non-coding RNAs (lncRNAs), a new type of RNAs, have been found to play important roles in HCC. LncRNAs have the ability to influence gene expression and protein activity. Dysregulation of lncRNAs has been linked to a growing number of liver disorders, including HCC. As a result, improved understanding of lncRNAs could lead to new insights into HCC etiology, as well as new approaches for the early detection and treatment of HCC. The latest results with respect to the role of lncRNAs in controlling multiple pathways of HCC were summarized in this study. The processes by which lncRNAs influence HCC advancement by interacting with chromatin, RNAs, and proteins at the epigenetic, transcriptional, and post-transcriptional levels were examined. This critical review also highlights recent breakthroughs in lncRNA signaling pathways in HCC progression, shedding light on the potential applications of lncRNAs for HCC diagnosis and therapy.

The Mouse Anxa6/miR-9-5p/Anxa2 Axis Modulates TGF-β1-induced Mouse Hepatic Stellate Cell (mHSC) Activation and CCl4-caused Liver Fibrosis

Chronic liver disease such as hepatic fibrosis is a major cause of morbidity and mortality and has been related to high individual risk of hepatocellular carcinoma (HCC). Hepatic stellate cells (HSCs) activation is a central event of hepatic fibrosis progression. In this study, the up-regulation of lncRNA ANXA2P2 (mouse Anxa6) was found in liver fibrosis. Within CCl₄-caused liver fibrosis murine model, Anxa6 knockdown partially ameliorated CCl₄-induced hepatic fibrosis and blocked the PI3K/Akt signaling activation. In TGF-β1-stimulated HSCs, Anxa6 knockdown partially inhibited TGF-β1-induced HSC activation and blocked the PI3K/Akt signaling activation. Mouse Anxa6 downstream mmu-miR-9-5p directly targeted Anxa2; Anxa6 negatively regulated mmu-miR-9-5p, and mmu-miR-9-5p negatively regulated mouse Anxa2. In TGF-β1-stimulated HSCs, miR-9-5p inhibitor promoted TGF-β1-induced HSC activation and PI3K/Akt signaling activation, whereas Anxa2 knockdown exerted opposite effects; Anxa2 knockdown significantly attenuated miR-9-5p inhibitor effects upon TGF-β1-stimulated HSCs. In conclusion, lncRNA ANXA2P2 (mouse Anxa6) expression is up-regulated in hepatic fibrosis and exerts pro-fibrotic effects on CCl₄-caused liver fibrosis model mice and TGF-β1-stimulated HSCs. The mouse Anxa6/miR-9-5p/Anxa2 axis and the PI3K/Akt pathway might participate in the functions of lncRNA ANXA2P2 (mouse Anxa6) on hepatic fibrosis.

lncRNA NONRATT013819.2 promotes transforming growth factor-β1-induced myofibroblastic transition of hepatic stellate cells by miR24-3p/lox

Long noncoding RNAs (lncRNAs) are key regulators of hepatic stellate cells (HSCs), yet the role of upregulated lncRNA-NONRATT013819.2 in activated HSCs remains uncertain. In this study, the effects of NONRATT013819.2 on proliferation, apoptosis, migration, and contraction of transforming growth factor (TGF)-β1-induced HSCs were investigated. The mechanisms of NONRATT013819.2 on the activated HSCs were explored by loss-of-function of NONRATT013819.2 and gain-of-function of the target gene. Here, TGF-β1 treatment resulted in a gradual increase in the expression of cytoskeleton markers (collagen, α-SMA, and TIMP1), NONRATT013819.2, miR24-3p, and lysyl oxidase (Lox) over time in HSCs. NONRATT013819.2 acted as a sponge of miR24-3p to competitively abolish the inhibition of the lox gene in HSCs. Silencing of NONRATT013819.2 suppressed the expression of cytoskeleton markers, proliferation, and the proportion of cells that entered the S-phase, and promoted apoptosis in TGF-β1-activated HSCs. These effects were reversed when lox overexpression was introduced simultaneously. Similarly, silencing of NONRATT013819.2 also blocked ECM reconstruction, while recused by lox overexpression in TGF-β1-activated HSCs. In conclusion, upregulation of NONRATT013819.2 promotes the myofibroblastic transition by competitively binding miR24-3p to release lox in HSCs. Therefore, targeted therapy of NONRATT013819.2 may have the potential for liver fibrosis.

The Long Noncoding RNA LINC00963 Inhibits Corneal Fibrosis Scar Formation by Targeting miR-143-3p

Corneal fibrosis is a complication of severe corneal injury, one of the major causes of vision loss. The formation of myofibroblasts has emerged as a key stimulative factor of corneal fibrosis. In the current study, we focused on the role of LINC00963 in regulating corneal fibrosis. Transforming growth factor β1 (TGF-β1) was used to induce human corneal stromal cells differentiating into corneal myofibroblasts, and the significant increase of α-smooth muscle actin (α-SMA) was verified by quantitative real-time PCR (qRT-PCR), western blot, and immunofluorescence, respectively. LINC00963 was identified to be one-half decreased compared with nonstimulated human corneal stromal cells, indicating that it might play a role in corneal fibrosis. Interestingly, overexpression of LINC00963 resulted in decreased formation of myofibroblasts indicating that it might exhibit an inhibiting effect. Moreover, bioinformatics tool was applied to predict the downstream target of LINC00963. We investigated that LINC00963 suppressed α-SMA induced by TGF-β1 in corneal fibroblasts, at least in part, by downregulating the expression of miR-143-3p. In addition, either LINC00963 promotion or miR-143-3p inhibition could significantly decrease myofibroblast contractility and collagen I and III secretion, which are the key to contribute to corneal fibrosis. Taken together, our study identified LINC00963 as a promising therapeutic target.

Role of long non-coding RNA-adducin 3 antisense RNA1 in liver fibrosis of biliary atresia

Biliary atresia (BA) is a devastating liver disease in neonates. Liver fibrosis is regarded as a universal and prominent feature of BA. Studies have revealed that long non-coding RNAs (lncRNAs) regulate cellular processes during the development of liver fibrosis in BA. Long non-coding RNA-adducin 3 antisense RNA1 (lnc-ADD3-AS1) has been shown to increase susceptibility to BA. However, the role of lnc-ADD3-AS1 in liver fibrosis in BA remains unclear. Here, we investigated the role of lnc-ADD3-AS1 in the proliferation, migration, and apoptosis of the immortalized human hepatic stellate cell (HSC) line, LX-2. We successfully overexpressed and silenced lnc-ADD3-AS1 in LX-2 cells using adenovirus vectors and evaluated the proliferation of transfected cells using the Cell Counting Kit-8 (CCK8) assay. Cell apoptosis was detected using annexin V-fluorescein isothiocyanate (FITC)/propidium iodide (PI) double staining and flow cytometry. We then analyzed cell migration by performing wound-scratch and transwell migration assays. Our results show that lnc-ADD3-AS1 significantly promoted LX-2 cell proliferation and attenuated apoptosis. More importantly, lncRNA-ADD3-AS1 significantly accelerated the migration of LX-2 cells. Our data indicated that lncRNA-ADD3-AS1 plays a role in the pathogenesis of liver fibrosis in patients with BA and may serve as a potential diagnostic marker for monitoring liver fibrosis in BA or as a therapeutic target for the disease.

Dasatinib ameliorates thioacetamide-induced liver fibrosis: modulation of miR-378 and miR-17 and their linked Wnt/β-catenin and TGF-β/smads pathways

Hepatic stellate cells activation (HSCs) plays a crucial role in the pathogenesis of liver fibrosis. Specific microRNAs have been suggested to affect the activation of HSCs via various signalling pathways including TGF-β/smads and Wnt/β-catenin pathways. Dasatinib is a multitarget inhibitor of many tyrosine kinases has recently studied for its anti-fibrotic effects in a variety of fibrous diseases. This study investigated the role of modulation of miRNA-378 and miRNA-17 in the pathogenesis of liver fibrosis through altering Wnt/β-catenin and TGF-β/smads pathways and evaluated the beneficial effect of the tyrosine kinase inhibitor, dasatinib, in thioacetamide-induced liver fibrosis model in mice. Treatment with dasatinib down-regulated miRNA-17 expression, leading to the restoration of WiF-1 and smad-7 which cause the inhibition of both Wnt/β-catenin and TGF-β/smads signalling. In addition, it upregulated miRNA-378 leading to the decrease of Wnt-10 which contributes to the suppression of activated HSCs.

The Roles and Mechanisms of lncRNAs in Liver Fibrosis

Long non-coding RNAs (lncRNAs) can potentially regulate all aspects of cellular activity including differentiation and development, metabolism, proliferation, apoptosis, and activation, and benefited from advances in transcriptomic and genomic research techniques and database management technologies, its functions and mechanisms in physiological and pathological states have been widely reported. Liver fibrosis is typically characterized by a reversible wound healing response, often accompanied by an excessive accumulation of extracellular matrix. In recent years, a range of lncRNAs have been investigated and found to be involved in several cellular-level regulatory processes as competing endogenous RNAs (ceRNAs) that play an important role in the development of liver fibrosis. A variety of lncRNAs have also been shown to contribute to the altered cell cycle, proliferation profile associated with the accelerated development of liver fibrosis. This review aims to discuss the functions and mechanisms of lncRNAs in the development and regression of liver fibrosis, to explore the major lncRNAs involved in the signaling pathways regulating liver fibrosis, to elucidate the mechanisms mediated by lncRNA dysregulation and to provide new diagnostic and therapeutic strategies for liver fibrosis.

Long non‑coding RNA MBI‑52 inhibits the development of liver fibrosis by regulating the microRNA‑466g/SMAD4 signaling pathway

Liver fibrosis is a wound healing response triggered by liver injury. In severe cases, it may develop into liver cirrhosis, liver cancer and liver failure. Long non-coding RNAs (lncRNAs) play key roles in the development of liver fibrosis. The present study aimed to investigate the role of lncRNA-MBI-52 (lnc-MBI-52) in the progression of liver fibrosis. Carbon tetrachloride (CCl₄)-induced injury was performed to establish a mouse liver fibrosis model, and exogenous transforming growth factor-β1 was used to establish a hepatic stellate cell (HSC) activation model. Reverse transcription-quantitative PCR and western blot analyses were performed to detect mRNA and protein expression, respectively. RNA pull-down assay was performed to assess the interaction between microRNA (miR)-466g and lnc-MBI-52 or SMAD4. Dual-luciferase reporter assay was performed to verify the target of miR-466g. lnc-MBI-52 was overexpressed in CCl₄-induced mouse liver fibrosis models and activated HSCs. lnc-MBI-52 knockdown suppressed liver fibrosis in vitro. Moreover, knockdown of lnc-MBI-52 downregulated α-smooth muscle actin and collagen type I expression. In addition, lnc-MBI-52 and SMAD4 were identified as targets of miR-466g. The effects of lnc-MBI-52 on HSC activation were reversed following transfection with miR-466g mimics or SMAD4 knockdown. lnc-MBI-52 miR-466g significantly decreased lnc-MBI-52 expression, while overexpression of lnc-MBI-52 suppressed miR-466g expression. The results of the RNA pull-down assay confirmed the interaction between miR-466g and lnc-MBI-52. Taken together, lnc-MBI-52 induced liver fibrosis by regulating the miR-466g/SMAD4 axis, which may provide a new possible strategy for liver fibrosis.

Noncoding RNAs Interactions in Hepatic Stellate Cells during Hepatic Fibrosis

Hepatic fibrosis is a reversible wound healing process following liver injury. Although this process is necessary for maintaining liver integrity, severe excessive extracellular matrix accumulation (ECM) could lead to permanent scar formation and destroy the liver structure. The activation of hepatic stellate cells (HSCs) is a key event in hepatic fibrosis. Previous studies show that most antifibrotic therapies focus on the apoptosis of HSCs and the prevention of HSC activation. Noncoding RNAs (ncRNAs) play a substantial role in HSC activation and are likely to be biomarkers or therapeutic targets for the treatment of hepatic fibrosis. This review summarizes and discusses the previously reported ncRNAs, including the microRNAs, long noncoding RNAs, and circular RNAs, highlighting their regulatory roles and interactions in the signaling pathways that regulate HSC activation in hepatic fibrosis.

LncRNA MEG3 reverses CCl4-induced liver fibrosis by targeting NLRC5

Liver fibrosis is a persistent pathological repair of chronic liver injury, which is characterized by excessive deposition of collagen-dominated extracellular matrix (ECM). It is well known that hepatic fibrosis can be reversed in the absence of etiology. Studies have shown that long non-coding RNA (Lnc RNA) maternally expressed gene3 (MEG3) has strong effects on the activation of hepatic stellata cells (HSCs). However, the function of MEG3 in the reversal of liver fibrosis has not been studied. In this experiment, we studied the content expression, function, and part of the potential mechanism of MEG3 in reversing liver fibrosis. In in vivo and in vitro models, we found that MEG3 was down-regulated during the formation of liver fibrosis, while it was up-regulated during the reversal of liver fibrosis. Then, it was found that the silencing of MEG3 could gradually restore the activity of the inactivated LX-2 cells, Overexpression of MEG3 can inhibit the activation of LX-2 cells, accelerate the reversal of liver fibrosis. Through catRAPID analysis, it was found that NLR family CARD domain containing 5 (NLRC5) may be a target of MEG3. We found that, after MEG3 silencing, NLRC5 expression was upregulated in LX-2 cells in the reverse phase, while, after MEG3 overexpression, NLRC5 expression was decreased. Further, we verified that MEG3 can target NLRC5 through RNA pull down experiment. Therefore, MEG3 may inhibit the activation of hepatic stellate cells by targeting NLRC5, thus accelerating the reversal of hepatic fibrosis.

Lnc-CPLC promotes the progression of colorectal cancer via regulating ZBTB34 by competitively binding miR-4319

Long noncoding RNAs (lncRNAs) have been considered as regulatory molecules that play crucial roles in diverse biological processes, including the regulation of tumor progression. However, in colorectal cancer (CRC), due to the complex regulatory relationships involved in lncRNAs, the details of the specific mechanism still need to be elucidated. To discover the key regulatory role of lncRNA in CRC, we used bioinformatics analysis methods for preliminary screening. Through the combination of in vitro and in vivo verification, we further comprehensively analyzed the specific regulation of the key gene and the related key lncRNA in CRC. We found that ZBTB34 and lnc-CPLC (CRC progression-associated lncRNA) had a strong correlation, which plays a key role in the regulation of CRC. Furthermore, by exerting the "sponge" function, lnc-CPLC could bind to miR4319 and release its binding to the 3'UTR of ZBTB34 mRNA. Our results reveal the mechanism of the lnc-CPLC/miR-4319/ZBTB34 signal axis in CRC and provide evidence for elucidating the complex molecular mechanisms in tumors.

MALAT1 promotes liver fibrosis by sponging miR‑181a and activating TLR4‑NF‑κB signaling

The aim of the present study was to investigate whether long non-coding RNA metastasis associated lung adenocarcinoma transcript 1 (MALAT1) could modulate activation and inflammation of hepatic stellate cell (HSCs) via regulation of a microRNA (miR)-181a-toll like receptor (TLR)4/nuclear factor (NF)-κB axis, thereby contributing to the development of liver fibrosis. A total of 151 patients with liver fibrosis were recruited, and the serum levels of alanine transaminase, aspartate aminotransferase and albumin were determined. Transforming growth factor (TGF)-β1 and LPS were used to activate and induce inflammation in the human HSC cell line LX2. MALAT1 was knocked using small interfering RNA or overexpressed, and an inhibitor and mimic of miR-181a-5p were used to examine the effect of MALAT1 and miR-181a-5p on the activation and inflammation of LX2 cells. Both MALAT1 and miR-181a-5p expression performed well in their ability to differentiate patients with liver fibrosis from healthy volunteers, and MALAT1 expression was associated with the severity of liver fibrosis. The expression levels of TLR4 and NF-κB were increased after stimulation with LPS or TGF-β1, but MALAT1 knockdown or miR-181a-5p mimic transfection abrogated this increase. Moreover, the TGF-β1-induced increase in viability, proliferation, migration, adhesion and collagen production, and the LPS-induced inflammation of LX2 cells were all reversed after MALAT1 knockdown or transfection with miR-181a-5p mimic. The MALAT1/miR-181a-5p axis was involved in regulating collagen production and inflammation by activating TLR4/NF-κB signaling, which may be conducive to liver fibrosis treatment in the future.

Identification of differentially expressed long noncoding RNAs and pathways in liver tissues from rats with hepatic fibrosis

To identify long non-coding RNAs (lncRNAs) and their potential roles in hepatic fibrosis in rat liver issues induced by CCl4, lncRNAs and genes were analyzed in fibrotic rat liver tissues by RNA sequencing and verified by quantitative reverse transcription polymerase chain reaction (qRT-PCR). Differentially expressed (DE) lncRNAs (DE-lncRNAs) and genes were subjected to bioinformatics analysis and used to construct a co-expression network. We identified 10 novel DE-lncRNAs that were downregulated during the hepatic fibrosis process. The cis target gene of DE-lncRNA, XLOC118358, was Met, and the cis target gene of the other nine DE-lncRNAs, XLOC004600, XLOC004605, XLOC004610, XLOC004611, XLOC004568, XLOC004580 XLOC004598, XLOC004601, and XLOC004602 was Nox4. The results of construction of a pathway-DEG co-expression network show that lncRNA-Met and lncRNAs-Nox4 were involved in oxidation-reduction processes and PI3K/Akt signaling pathway. Our results identified 10 DE-lncRNAs related to hepatic fibrosis, and the potential roles of DE-lncRNAs and target genes in hepatic fibrosis might provide new therapeutic strategies for hepatic fibrosis.

Hepatic stellate cells role in the course of metabolic disorders development - A molecular overview

Fibrosis is characterized by an abnormal accumulation of extracellular matrix (ECM) constituents in the liver parenchyma that lead to hepatic cirrhosis. After liver injury, the hepatic stellate cells (HSCs) undergo a response called "activation", transforming the cells into proliferative, fibrogenic and contractile myofibroblasts, representing the main collagen-producing cells in the injured tissue. Activated HSCs are considered as pro-inflammatory cells producing cytokines and several hepatomatogens; they are additionally involved in the recruitment of Kupffer cells, circulating monocytes and macrophages through the production of chemokines. Moreover, HSC have been proposed as being involved in the development of insulin resistance mainly mediated by their inflammatory properties, which undeniably links their activation to the development of diabetes and Non-alcoholic fatty liver disease. In addition, when the liver is injured, a complex interaction between hepatocytes and HSCs occurs, inducing mitochondrial dysfunction, which contributes to the accumulation of fats in hepatocytes that trigger to liver lipotoxicity. These mechanisms underlying the activation of HSC suggest their major role in the development of metabolic disorders. It turns out that several molecules including MicroRNAs and proteins have the ability to inhibit the activation and the proliferation of HSCs, which makes them interesting therapeutic targets for the subsequent management of metabolic conditions. This review focuses on the mechanisms and molecular pathways underlying the initiation and onset of metabolic disorders following HSCs activation, as well as on molecular therapeutic targets, which could limit their fibrogenic transdifferentiation and therefore improve the liver condition in the course of metabolic imbalance.

Circular RNA as An Epigenetic Regulator in Chronic Liver Diseases

Circular RNA (circRNA) is a type of non-coding RNA characterized by a covalently closed continuous loop. CircRNA is generated by pre-mRNA through back-splicing and is probably cleared up by extracellular vesicles. CircRNAs play a pivotal role in the epigenetic regulation of gene expression at transcriptional and post-transcriptional levels. Recently, circRNAs have been demonstrated to be involved in the regulation of liver homeostasis and diseases. However, the epigenetic role and underlying mechanisms of circRNAs in chronic liver diseases remain unclear. This review discussed the role of circRNAs in non-neoplastic chronic liver diseases, including alcoholic liver disease (ALD), metabolic-associated fatty liver disease (MAFLD), viral hepatitis, liver injury and regeneration, liver cirrhosis, and autoimmune liver disease. The review also highlighted that further efforts are urgently needed to develop circRNAs as novel diagnostics and therapeutics for chronic liver diseases.

Identification of plasma lncRNA-ATB levels in hepatitis B virus-related cirrhosis and non-cirrhotic chronic hepatitis B patients

Long non-coding RNA-ATB (LncRNA-ATB) which is activated by transforming growth factor-β (TGF-β), is a key regulator of TGF-β signaling pathway. TGF-β plays an important role in various pathogenic processes, from inflammation and fibrosis to cirrhosis and cancer. In this study, we evaluated the plasma levels of lncRNA-ATB in patients with hepatitis B virus (HBV)-related cirrhosis and non-cirrhotic patients with chronic hepatitis B (CHB) and investigated the clinical values. Plasma samples were collected from 44 HBV-related cirrhosis patients, 45 non-cirrhotic CHB and 75 healthy controls. Briefly, after total RNA extraction and cDNA synthesis, quantitative real-time PCR (qPCR) was performed to detect plasma lncRNA-ATB levels. Results show the plasma levels of lncRNA-ATB in HBV-related cirrhosis patients were significantly higher in comparison to healthy controls (Fold change=2.60, p value=0.04). Also, we determined plasma levels of lncRNA-ATB as a specific biomarker of HBV-related cirrhosis (AUC=0.65, p value=0.03, Sensitivity 61.36%; Specificity 70.00%). In addition to, we investigated the plasma levels of lncRNA-ATB in non-cirrhotic CHB patients were significantly lower than healthy controls (Fold change= 0.33, p value=0.01). We also indicated plasma lncRNA-ATB levels were as a sensitive biomarker for diagnosis of non-cirrhotic CHB patients compared with healthy (AUC=0.66, p value=0.00, Sensitivity 71.11%; Specificity 57.78%). According to our results, circulating lncRNA-ATB has good specificity for diagnosing hepatitis B virus (HBV)-related cirrhosis and good sensitivity for diagnosis of non-cirrhotic chronic hepatitis B (CHB) patients.

lncRNA PAPPA-AS1 Induces the Development of Hypertrophic Scar by Upregulating TLR4 through Interacting with TAF15

Hypertrophic scar (HTS) is a complicated pathological process induced mainly by burns and wounds, with abnormal proliferation of fibroblasts and the transformation of fibroblasts to myofibroblasts. PAPPA-AS1, a differentially expressed long noncoding RNA (lncRNA) in the HTS tissues, attracted our interests in its potential role and mechanism in the development and process of HTS. In the present study, the regulatory effect of lncRNA PAPPA-AS1 on the Toll-like receptor 4 (TLR4) signal pathway, as well as the molecular mechanism, was investigated. Bioinformatics analysis was utilized to screen the differentially expressed lncRNAs in HTS tissues. PAPPA-AS1 was significantly upregulated in both HTS tissues and hypertrophic scar fibroblast (HTsFb) cells. The expression levels of TLR4, MyD88, TGF-β1, collagen I, collagen III, and α-SMA were greatly elevated in HTsFb cells. By knocking down PAPPA-AS1, the proliferation of HTsFb cells, TLR4, and TGF-β1 signal pathway and the expression of fibrosis markers both in HTsFb cells and HTS tissues were suppressed. It was accompanied by the alleviated pathological state in the HTS tissues, which were significantly reversed by cotransfecting with the pcDNA3.1-TLR4 vector. Positive correlation and interaction were observed between PAPPA-AS1 and TAF15 and between TAF15 and the promoter of TLR4, respectively. In conclusion, lncRNA PAPPA-AS1 might induce the development of HTS by upregulating TLR4 through interacting with TAF15.

Global analysis of expression, maturation and subcellular localization of mouse liver transcriptome identifies novel sex-biased and TCPOBOP-responsive long non-coding RNAs

BACKGROUND

While nuclear transcription and RNA processing and localization are well established for protein coding genes (PCGs), these processes are poorly understood for long non-coding (lnc)RNAs. Here, we characterize global patterns of transcript expression, maturation and localization for mouse liver RNA, including more than 15,000 lncRNAs. PolyA-selected liver RNA was isolated and sequenced from four subcellular fractions (chromatin, nucleoplasm, total nucleus, and cytoplasm), and from the chromatin-bound fraction without polyA selection.

RESULTS

Transcript processing, determined from normalized intronic to exonic sequence read density ratios, progressively increased for PCG transcripts in going from the chromatin-bound fraction to the nucleoplasm and then on to the cytoplasm. Transcript maturation was similar for lncRNAs in the chromatin fraction, but was significantly lower in the nucleoplasm and cytoplasm. LncRNA transcripts were 11-fold more likely to be significantly enriched in the nucleus than cytoplasm, and 100-fold more likely to be significantly chromatin-bound than nucleoplasmic. Sequencing chromatin-bound RNA greatly increased the sensitivity for detecting lowly expressed lncRNAs and enabled us to discover and localize hundreds of novel regulated liver lncRNAs, including lncRNAs showing sex-biased expression or responsiveness to TCPOBOP a xenobiotic agonist ligand of constitutive androstane receptor (Nr1i3).

CONCLUSIONS

Integration of our findings with prior studies and lncRNA annotations identified candidate regulatory lncRNAs for a variety of hepatic functions based on gene co-localization within topologically associating domains or transcription divergent or antisense to PCGs associated with pathways linked to hepatic physiology and disease.

LncRNA Neat1 expedites the progression of liver fibrosis in mice through targeting miR-148a-3p and miR-22-3p to upregulate Cyth3

Liver fibrosis is a common response to chronic liver injury, ultimately leading to cirrhosis. The activation of hepatic stellate cells (HSCs) plays a dominant role in liver fibrosis. The regulatory roles of long noncoding RNAs (lncRNAs) in multiple human diseases have been observed. This study was dedicated to investigating the regulatory effects of the lncRNA nuclear paraspeckle assembly transcript 1 (Neat1) on liver fibrosis and HSC activation. Upregulation of Neat1 and cytohesin 3 (Cyth3) and downregulation of miR-148a-3p and miR-22-3p were observed in mouse fibrotic liver tissues. Knockdown of Neat1 or Cyth3 attenuated liver fibrosis and collagen deposition in vivo and the activation of HSCs in vitro. An miR-148a-3p and miR-22-3p inhibitor facilitated HSC activation and collagen fiber expression. Neat1 directly targeted miR-148a-3p and miR-22-3p to modulate Cyth3 expression. Knockdown of Neat1 inhibited Cyth3 expression via the competing endogenous RNA (ceRNA) mechanism of sponging miR-148a-3p and miR-22-3p to regulate liver fibrosis and HSC activation. The ceRNA regulatory network may promote a better understanding of liver fibrogenesis, contribute to an original agreement of liver fibrosis etiopathogenesis and provide insights into the development of a novel domain of lncRNA-directed therapy against liver fibrosis.

Downregulated long non-coding RNA LINC01093 in liver fibrosis promotes hepatocyte apoptosis via increasing ubiquitination of SIRT1

The apoptosis of hepatocytes contributes to the activation of hepatic stellate cells (HSCs), thus promoting the accumulation of extracellular matrix proteins and aggravating liver fibrosis. Silent information regulator 1 (SIRT1) is an anti-fibrotic protein whose downregulation induces hepatocyte apoptosis. This study aims to identify whether SIRT1 is regulated by long non-coding RNA LINC01093 and explore its underlying mechanisms. Liver fibrosis was induced in mice using CCl4, and the differential expressions of several fibrosis-related long noncoding RNAs were detected in liver tissues. The effect of LINC01093 on cell apoptosis and viability of hepatocytes were investigated after LINC01093 overexpression or knockdown using flow cytometry and MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay. The anti-fibrotic effect of LINC01093 overexpression was observed in vivo. LncRNA LINC01093 is downregulated in CCl4-induced liver tissues and TGF-β1-stimulated hepatocytes. Downregulated LINC01093 promoted cell apoptosis and inhibited cell viability of hepatocytes. The co-culture between LINC01093-knockdown hepatocytes and HSCs increased the expressions of pro-fibrotic proteins. Downregulated LINC01093 promoted hepatocyte apoptosis via promoting degradation and ubiquitination of SIRT1 under TGF-β1 stimulation. The injection of LINC01093-overexpressing vectors alleviated liver fibrosis in vivo. In liver fibrosis, the downregulated LINC01093 promoted hepatocyte apoptosis, which is mediated by increasing the degradation and ubiquitination of SIRT1.

Role of long non‑coding RNAs and related epigenetic mechanisms in liver fibrosis (Review)

Liver fibrosis is one of the major liver pathologies affecting patients worldwide. It results from an improper tissue repair process following liver injury or inflammation. If left untreated, it ultimately leads to liver cirrhosis and liver failure. Long non‑coding RNAs (lncRNAs) have been implicated in a wide variety of diseases. They can regulate gene expression and modulate signaling. Some of the lncRNAs promote, while others inhibit liver fibrosis. Similarly, other epigenetic processes, such as methylation and acetylation regulate gene transcription and can modulate gene expression. Notably, there are several regulatory associations of lncRNAs with other epigenetic processes. A major mechanism of action of long non‑coding RNAs is to competitively bind to their target microRNAs (miRNAs or miRs), which in turn affects miRNA availability and bioactivity. In the present review, the role of lncRNAs and related epigenetic processes contributing to liver fibrosis is discussed. Finally, various potential therapeutic approaches targeting lncRNAs and related epigenetic processes, which are being considered as possible future treatment targets for liver fibrosis are identified.

Effect of long non‑coding RNA AK021443 on promoting hepatic fibrosis in vitro

Long non‑coding (lnc)RNAs serves an important role in the occurrence and development of hepatic fibrosis. lncRNA AK021443 is highly expressed in hepatocellular carcinoma (HCC) and promotes HCC cell proliferation, invasion and migration. The present study aimed to investigate the effect of AK021443 on hepatic fibrosis. AK021443 was overexpressed in the human LX‑2 hepatic stellate cell (HSC) line using a plasmid to observe its effect on hepatic fibrosis in vitro. A Cell Counting Kit‑8 assay was performed to assess cell proliferation, whereas cell cycle distribution and related proteins were analyzed via flow cytometry and western blotting, respectively. The protein expression levels of epithelial‑mesenchymal transition (EMT)‑associated and extracellular matrix (ECM) proteins were also analyzed via western blotting. Immunofluorescence was conducted to observe the generation of collagen1, and the activity of inflammatory factors and reactive oxygen species (ROS) was also analyzed. Compared with the pcDNA group, AK021443 overexpression significantly promoted cell proliferation, enhanced the transition of cells from G₁ to S phase and increased the expression of cyclin‑dependent kinase 2 and cyclin D1, but reduced the p21 protein expression levels. In addition, EMT capabilities, ECM deposition and the generation of collagen1 were increased by AK021443 overexpression compared with the pcDNA group. Moreover, AK021443 overexpression significantly increased the release of inflammatory cytokines, including TGF‑β, interleukin‑1β, platelet derived growth factor, epidermal growth factor and ROS, compared with the pcDNA group. In conclusion, the present study suggested that AK021443 overexpression increased HSC proliferation, activation and the proinflammatory response, indicating the potential role of AK02144 in aggravating hepatic fibrosis.

Circular RNA circPSD3 alleviates hepatic fibrogenesis by regulating the miR-92b-3p/Smad7 axis

Recently, circular RNAs (circRNAs) have been frequently reported to be involved in hepatocellular carcinoma (HCC) development and progression. However, the role of circRNAs in hepatic fibrosis (HF) is still unclear. Our previous high-throughput screen revealed changes in many circRNAs in mice with carbon tetrachloride (CCl₄)-induced HF. For instance, the expression of circPSD3, a circRNA derived from the Pleckstrin and Sec7 domain-containing 3 (PSD3) gene, was considerably downregulated in primary hepatic stellate cells (HSCs) and liver tissues of mice with CCl₄-induced HF compared to those in the vehicle group. In vivo overexpression of circPSD3 using AAV8-circPSD3 arrested the deterioration of CCl₄-induced HF as indicated by reduced serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) content, liver hydroxyproline level, collagen deposition, and pro-fibrogenic gene and pro-inflammatory cytokine levels. Moreover, in vitro loss-of-function and gain-of-function analyses suggested that circPSD3 inhibited the activation and proliferation of HSCs. Mechanistically, circPSD3 served as a sponge for miR-92b-3p, subsequently promoting the expression of Smad7. In conclusion, our present findings reveal a novel mechanism by which circPSD3 alleviates hepatic fibrogenesis by targeting the miR-92b-3p/Smad7 axis, and they also indicate that circPSD3 may serve as a potential biomarker for HF.

LncRNA NEAT1 promotes proliferation, migration, invasion and epithelial-mesenchymal transition process in TGF-β2-stimulated lens epithelial cells through regulating the miR-486-5p/SMAD4 axis

Background

Abnormal proliferation, metastasis and epithelial-mesenchymal transformation (EMT) of lens epithelial cells (LECs) are direct factors of posterior capsular opacification (PCO). Nuclear enriched abundant transcript 1 (NEAT1) has been shown to promote cell proliferation, metastasis and EMT, but whether it affects the progression of PCO is unclear.

Methods

The expression of NEAT1, microRNA-486-5p (miR-486-5p) and Drosophila mothers against decapentaplegic 4 (SMAD4) was determined using quantitative real-time polymerase chain reaction (qRT-PCR). The proliferation of cells was measured via 3-(4, 5-dimethyl-2 thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide (MTT) assay. Transwell assay was employed to detect the migration and invasion of cells. The levels of EMT marker proteins, SMAD4 protein and transforming growth factor-β (TGF-β)/SMAD signaling pathway-related proteins were assessed by western blot (WB) analysis. Further, the relationship between miR-486-5p and NEAT1 or SMAD4 was confirmed by dual-luciferase reporter assay, RNA immunoprecipitation (RIP) assay and biotin-labeled RNA pull-down assay.

Results

NEAT1 is upregulated and miR-486-5p is downregulated in the posterior capsular tissues of PCO patients and TGF-β2-induced LECs. Interference of NEAT1 reverses the promoting effect of TGF-β2 on the proliferation, migration, invasion and EMT of LECs. MiR-486-5p can be sponged by NEAT1, and its inhibitor reverses the suppression effect of NEAT1 silencing on the progression of TGF-β2-induced LECs. SMAD4 functions as a target of miR-486-5p, and its overexpression recovers the inhibition effect of miR-486-5p overexpression on the progression of TGF-β2-induced LECs. The activity of the TGF-β/SMAD signaling pathway is regulated by the NEAT1/miR-486-5p/SMAD4 axis.

Conclusion

Our study shows that NEAT1 has a positive effect on the progression of PCO and is expected to become a new target for PCO treatment.

The pro-apoptosis and pro-inflammation role of LncRNA HIF1A-AS1 in Coxsackievirus B3-induced myocarditis via targeting miR-138

Background

Cardiomyocyte apoptosis and inflammation induced by Coxsackievirus B3 (CVB3) are key pathogenetic mechanisms in viral myocarditis. Alterations in microRNAs and lncRNAs are associated with cardiac remodeling. However, whether the microRNA and lncRNA interact to regulate cardiomyocyte apoptosis and inflammation is unknown.

Methods

BALB/c mice were infected with CVB3 to generate acute viral myocarditis model. The expression levels of lncRNA HIF1A-AS1 and miR-138 were examined in mouse myocardium and primary cardiomyocytes with CVB3 infection. We then knocked down HIF1A-AS1 by siRNA and upregulated miR-138 by microRNA mimics in cardiomyocytes.

Results

The expression of lncRNA HIF1A-AS1was significantly increased in CVB3-induced myocardium and cardiomyocytes. As documented by flow cytometry, silencing of HIF1A-AS1 alleviated late apoptosis (5.1%±2.8% vs. 17.2%±4.2%, P<0.01) and ROS production (68.73%±2.78% vs. 90.40%±2.86%, P<0.01) compared to their levels in cardiomyocytes transfected with control siRNA. The content of proinflammatory cytokines was substantially decreased by HIF1A-AS1 siRNA. Furthermore, we identified that HIF1A-AS1 bound to miR-138 and significantly suppressed miR-138 expression. Blocking HIF1A-AS1 attenuated IκBα phosphorylation and NF-κB activity, while cotransfection with miR-138 mimics markedly reversed its effect.

Conclusions

In conclusion, lncRNA HIF1A-AS1 promotes NF-κB signaling and subsequently aggravates cardiomyocyte apoptosis and inflammation via targeting miR-138.

Emerging role of lncRNAs in renal fibrosis

Fibrosis is the final common pathological feature of a wide variety of chronic kidney disease (CKD). However, an understanding of the mechanisms underlying the development of renal fibrosis remains challenging and controversial. As the current focus of molecular research, noncoding RNAs (ncRNAs), mainly microRNAs (miRNAs), long noncoding RNAs (lncRNAs) and circular noncoding RNAs (circRNAs), have powerful and abundant biological functions, which essentially makes them mediators of the physiological and pathological processes of various system diseases. The role of ncRNAs in renal fibrosis has also received great attention in recent years, but most research has mainly focused on miRNAs. In fact, although a large number of studies of lncRNAs have emerged recently, the role these molecules play in renal fibrosis haven't been fully understood till now. Thus, this review discusses the discovery of lncRNAs and their biological functions in different types of renal fibrosis, as well as the imminent applications of these findings in clinical use. Undoubtedly, in the future, further understanding of the function of all types of lncRNAs will reveal large breakthroughs in the treatment of renal fibrosis.

hsa_circ_0004018 suppresses the progression of liver fibrosis through regulating the hsa-miR-660-3p/TEP1 axis

Efforts have been made in the prevention and treatment of liver fibrosis. The inhibition or depletion of the hepatic stellate cells (HSCs) has been considered as a potential approach. Recently, there are numbers of studies about the role of the circular RNA in the disease progression. However, the role of circular RNA in the regulation of HSCs and the progression of liver fibrosis remained elusive. In this study, we constructed a CCl4-induced liver fibrosis mouse model and overexpressed hsa_circ_0004018 in HSCs. Then, salvianolic acid B was used to treat HSCs in vitro. We found that hsa_circ_0004018 is downregulated in liver fibrogenesis. Luciferase reporter assay was performed to verify the interaction of hsa_circ_0004018, hsa-miR-660-3p and TEP1. It showed that hsa_circ_0004018 may act as a sponge of hsa-miR-660-3p, which can target and downregulate the expression of TEP1. hsa_circ_0004018 expressing lentivirus was used to investigate the in-vivo function of hsa_circ_0004018 in CCl4-induced liver fibrosis mice. We also reveal that the hsa_circ_0004018/hsa-miR-660-3p/TEP1 axis contributes to the proliferation and activation of HSCs. In addition, the overexpression of hsa_circ_0004018 alleviated the progression of liver fibrosis. In conclusion, our study highlights hsa_circ_0004018 as a potential biomarker and therapeutic target for liver fibrosis.

LncRNA SNHG7 promotes cardiac remodeling by upregulating ROCK1 via sponging miR-34-5p

Previous studies have shown that lncRNA small nuclear RNA host gene 7 (lncRNA SNHG7) played an important role in cancer progression. However, the role of lncRNA SNHG7 in cardiac fibrosis is still poorly understood. In this study, the results of quantitative real time polymerase chain reaction (qRT-PCR) analysis showed that lncRNA SNHG7 was over expressed in the infarcted and peri-infarcted area in the left ventricle after MI in mice. Western blot analysis showed that knockdown of SNHG7 decreased the expression of collagen type 1 (Col1)and α-smooth muscle actin (α-SMA). Echocardiographic study suggested that inhibition of SNHG7 improved cardiac function after MI in mice. Luciferase assay indicated SNHG7 could act as a competing endogenous RNA (ceRNA) by sponging miR-34-5p. The MTT cell proliferation assay and 5-ethynyl-2’-deoxyuridine (EdU) labelling assay revealed that co-transfection of SNHG7 and miR-34-5p inhibited cell viability and proliferation of cardiac fibroblasts (CF). All the results indicated that lncRNA SNHG7 could promote cardiac fibrosis via targeting miR-34-5p through acting as a ceRNA in mice after MI. Silencing of SNHG7 could attenuate deposition of collagens and improve cardiac function. miR-34-5p could suppress the fibrogenesis of CF by targeting ROCK1 and abolish SNHG7-induced CF proliferation and fibroblast-to-myofibroblast transition.

lncRNA ZFAS1 promotes lung fibroblast-to-myofibroblast transition and ferroptosis via functioning as a ceRNA through miR-150-5p/SLC38A1 axis

Pulmonary fibrosis (PF) is a lethal fibrotic lung disease. The role of lncRNAs in multiple diseases has been confirmed, but the role and mechanism of lncRNA zinc finger antisense 1 (ZFAS1) in the progression of PF need to be elucidated further. Here, we found that lncRNA ZFAS1 was upregulated in bleomycin (BLM)-induced PF rats lung tissues and transforming growth factor-β1 (TGF-β1)-treated HFL1 cells, and positively correlated with the expression of solute carrier family 38 member 1 (SLC38A1), which is an important regulator of lipid peroxidation. Moreover, knockdown of lncRNA ZFAS1 significantly alleviated TGF-β1-induced fibroblast activation, inflammation and lipid peroxidation. In vivo experiments showed that inhibition of lncRNA ZFAS1 abolished BLM-induced lipid peroxidation and PF development. Mechanistically, silencing of lncRNA ZFAS1 attenuated ferroptosis and PF progression by lncRNA ZFAS1 acting as a competing endogenous RNA (ceRNA) and sponging miR-150-5p to downregulate SLC38A1 expression. Collectively, our studies demonstrated the role of the lncRNA ZFAS1/miR-150-5p/SLC38A1 axis in the progression of PF, and may provide a new biomarker for the treatment of PF patients.

Expression of the Long Noncoding RNA GAS5 Correlates with Liver Fibrosis in Patients with Nonalcoholic Fatty Liver Disease

BACKGROUND

Advanced liver fibrosis is the most important prognostic factor in nonalcoholic fatty liver disease (NAFLD). The long noncoding RNA (lncRNA), growth arrest-specific transcript 5 (GAS5), is associated with the inhibition of liver fibrogenesis, and its levels are decreased in cirrhotic liver.

METHODS

We analyzed 51 patients with NAFLD, the diagnosis of which was confirmed by liver biopsy. Expression of GAS5 in both the liver and plasma of the patients was analyzed using a quantitative real-time polymerase chain reaction according to the fibrosis stage.

RESULTS

Plasma GAS5 expression was significantly higher in patients with advanced fibrosis than in those without. As the fibrosis progressed, GAS5 expression in plasma increased, with the exception of that in cirrhotic livers. Plasma levels of GAS5 were lower in patients with cirrhosis than in those with advanced fibrosis.

CONCLUSION

Elevated circulating levels of the lncRNA GAS5 are associated with the progression of liver fibrosis prior to the development of cirrhosis.

LncRNAs Act as a Link between Chronic Liver Disease and Hepatocellular Carcinoma

Long non-coding RNAs (lncRNAs) are emerging as important contributors to the biological processes underlying the pathophysiology of various human diseases, including hepatocellular carcinoma (HCC). However, the involvement of these molecules in chronic liver diseases, such as nonalcoholic fatty liver disease (NAFLD) and viral hepatitis, has only recently been considered in scientific research. While extensive studies on the pathogenesis of the development of HCC from hepatic fibrosis have been conducted, their regulatory molecular mechanisms are still only partially understood. The underlying mechanisms related to lncRNAs leading to HCC from chronic liver diseases and cirrhosis have not yet been entirely elucidated. Therefore, elucidating the functional roles of lncRNAs in chronic liver disease and HCC can contribute to a better understanding of the molecular mechanisms, and may help in developing novel diagnostic biomarkers and therapeutic targets for HCC, as well as in preventing the progression of chronic liver disease to HCC. Here, we comprehensively review and briefly summarize some lncRNAs that participate in both hepatic fibrosis and HCC.

The Roles and Mechanisms of lncRNAs in Liver Fibrosis

Many studies have revealed that circulating long noncoding RNAs (lncRNAs) regulate gene and protein expression in the process of hepatic fibrosis. Liver fibrosis is a reversible wound healing response followed by excessive extracellular matrix accumulation. In the development of liver fibrosis, some lncRNAs regulate diverse cellular processes by acting as competing endogenous RNAs (ceRNAs) and binding proteins. Previous investigations demonstrated that overexpression of lncRNAs such as H19, maternally expressed gene 3 (MEG3), growth arrest-specific transcript 5 (GAS5), Gm5091, NR_002155.1, and HIF 1alpha-antisense RNA 1 (HIF1A-AS1) can inhibit the progression of liver fibrosis. Furthermore, the upregulation of several lncRNAs [e.g., nuclear paraspeckle assembly transcript 1 (NEAT1), hox transcript antisense RNA (Hotair), and liver-enriched fibrosis-associated lncRNA1 (lnc-LFAR1)] has been reported to promote liver fibrosis. This review will focus on the functions and mechanisms of lncRNAs, the lncRNA transcriptome profile of liver fibrosis, and the main lncRNAs involved in the signalling pathways that regulate hepatic fibrosis. This review provides insight into the screening of therapeutic and diagnostic markers of liver fibrosis.

Long non-coding RNA HOTAIR drives EZH2-dependent myofibroblast activation in systemic sclerosis through miRNA 34a-dependent activation of NOTCH

Background

Systemic sclerosis (SSc) is characterised by autoimmune activation, tissue and vascular fibrosis in the skin and internal organs. Tissue fibrosis is driven by myofibroblasts, that are known to maintain their phenotype in vitro, which is associated with epigenetically driven trimethylation of lysine 27 of histone 3 (H3K27me3).

Methods

Full-thickness skin biopsies were surgically obtained from the forearms of 12 adult patients with SSc of recent onset. Fibroblasts were isolated and cultured in monolayers and protein and RNA extracted. HOX transcript antisense RNA (HOTAIR) was expressed in healthy dermal fibroblasts by lentiviral induction employing a vector containing the specific sequence. Gamma secretase inhibitors were employed to block Notch signalling. Enhancer of zeste 2 (EZH2) was blocked with GSK126 inhibitor.

Results

SSc myofibroblasts in vitro and SSc skin biopsies in vivo display high levels of HOTAIR, a scaffold long non-coding RNA known to direct the histone methyltransferase EZH2 to induce H3K27me3 in specific target genes. Overexpression of HOTAIR in dermal fibroblasts induced EZH2-dependent increase in collagen and α-SMA expression in vitro, as well as repression of miRNA-34A expression and consequent NOTCH pathway activation. Consistent with these findings, we show that SSc dermal fibroblast display decreased levels of miRNA-34a in vitro. Further, EZH2 inhibition rescued miRNA-34a levels and mitigated the profibrotic phenotype of both SSc and HOTAIR overexpressing fibroblasts in vitro.

Conclusions

Our data indicate that the EZH2-dependent epigenetic phenotype of myofibroblasts is driven by HOTAIR and is linked to miRNA-34a repression-dependent activation of NOTCH signalling.

TGF-β in Hepatic Stellate Cell Activation and Liver Fibrogenesis-Updated 2019

Liver fibrosis is an advanced liver disease condition, which could progress to cirrhosis and hepatocellular carcinoma. To date, there is no direct approved antifibrotic therapy, and current treatment is mainly the removal of the causative factor. Transforming growth factor (TGF)-β is a master profibrogenic cytokine and a promising target to treat fibrosis. However, TGF-β has broad biological functions and its inhibition induces non-desirable side effects, which override therapeutic benefits. Therefore, understanding the pleiotropic effects of TGF-β and its upstream and downstream regulatory mechanisms will help to design better TGF-β based therapeutics. Here, we summarize recent discoveries and milestones on the TGF-β signaling pathway related to liver fibrosis and hepatic stellate cell (HSC) activation, emphasizing research of the last five years. This comprises impact of TGF-β on liver fibrogenesis related biological processes, such as senescence, metabolism, reactive oxygen species generation, epigenetics, circadian rhythm, epithelial mesenchymal transition, and endothelial-mesenchymal transition. We also describe the influence of the microenvironment on the response of HSC to TGF-β. Finally, we discuss new approaches to target the TGF-β pathway, name current clinical trials, and explain promises and drawbacks that deserve to be adequately addressed.

Significance of expression of lncRNA-ATB in serum of patients with cholestatic liver disease

BACKGROUND

Cholestatic liver disease (CSLD) refers to a collection of liver diseases that can cause cholestasis. The etiology of CSLD is complex, the pathogenesis needs to be elucidated, and there is still a lack of effective treatment. Over the past decade, there has been a deep understanding of many aspects of CSLD, which provides more effective means for its accurate diagnosis and treatment. However, many problems are still pending, and further research is urgently needed.

AIM

To observe the difference of serum lncRNA-ATB levels between patients with intrahepatic cholestasis and normal people, and to explore the correlation between the changes of serum lncRNA-ATB and disease condition and prognosis in patients with intrahepatic cholestasis.

METHODS

Seventy-five patients with intrahepatic cholestasis of different etiologies and 30 healthy controls were included. The expression of lncRNA-ATB in serum samples of the above subjects was detected by qRT-PCR. The levels of lncRNA-ATB between normal controls and patients with cholestasis and between patients with different degrees of cholestasis were analyzed. Linear correlation analysis was used to analyze the correlation between the changes of lncRNA-ATB and clinical biochemical indicators, and receiver operating characteristic curve analysis was performed to analyze the clinical significance of the changes of lncRNA-ATB in judging the condition of intrahepatic cholestasis.

RESULTS

Compared with the healthy control group, lncRNA-ATB increased significantly in the serum of patients with intrahepatic cholestasis (P < 0.05). There was no significant difference in the expression of lncRNA-ATB between patients with cholestatic liver disease caused by different etiologies and and between patients with different courses of cholestasis (P > 0.05). Serum lncRNA-ATB decreased with the aggravation of cholestasis (P < 0.001). There was a negative correlation between lncRNA-ATB and total bile acid (r = -0.627, P < 0.001). The area under the curve of lncRNA-ATB in the diagnosis of cholestasis liver disease was 0.856 (95%CI: 0.809-0.904, P < 0.001), with a sensitivity of 81.42% and specificity of 73.45%.

CONCLUSION

The level of lncRNA-ATB in serum of patients with intrahepatic cholestasis liver disease is significantly increased, and it decreases with the aggravation of cholestasis. The expression level of LncRNA-ATB is expected to be a biomarker for judging the condition and prognosis of patients with intrahepatic cholestasis.

Long Noncoding RNA LL35/Falcor Regulates Expression of Transcription Factor Foxa2 in Hepatocytes in Normal and Fibrotic Mouse Liver

Long noncoding RNAs (lncRNA) play important roles in the regulation of transcription, splicing, translation, and other processes in the cell. Human and mouse lncRNA (DEANR1 and LL35/Falcor, respectively) located in the genomic environment in close proximity to the Foxa2 transcription factor were discovered earlier. In this work, tissue-specific expression of LL35/Falcor lncRNA has been shown in mouse liver and lungs. The use of antisense oligonucleotides allowed us to achieve LL35/Falcor lncRNA downregulation by 90%. As a result, the level of Foxa2 mRNA and protein dropped, which confirms the involvement of LL35/Falcor lncRNA in the regulation of transcription factor Foxa2. We have shown a decrease in the expression of LL35 lncRNA in liver fibrosis, which correlates with the previously published data for mRNA Foxa2. Thus, lncRNA LL35 regulates Foxa2 expression in the liver not only in normal conditions, but also during development of fibrosis, which allows one to consider lncRNA a biomarker of this pathological process.