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Am J Physiol Gastrointest Liver Physiol 298: G101-G106, 2010. First published November 5, 2009; doi: 10.1152/ajpgi.00220.2009.--Activation of hepatic stellate cells (HSC) results in their proliferation and in the secretion of extracellular matrix (ECM) proteins, which leads to hepatic fibrosis, microRNAs (miRNAs) have been shown to regulate various cell functions, such as proliferation, differentiation, and apoptosis. Hence, we have analyzed the miRNAs that were differentially expressed in HSC isolated from sham-operated and bile duct-ligated rats. Expression of two miRNAs, miRNA-150 and miRNA-194, was reduced in HSC isolated from fibrotic rats compared with sham-operated animals. These two miRNAs were overexpressed in LX-2 cells, and their ability to inhibit cell proliferation, the expression of smooth muscle [alpha]-actin (SMA), a marker for activation, and collagen type I, a marker for ECM secretion, was determined. Overexpression of these two miRNAs resulted in a significant inhibition of proliferation (P < 0.05) and reduced SMA and collagen I levels compared with either untreated cells or nonspecific miRNA-expressing cells. Next, the protein targets of these two miRNAs were found using bioinformatics approaches. C-myb was found to be a target for miRNA-150, and rac 1 was found to be one of the targets for miRNA-194. Therefore, we studied the expression of these two proteins by overexpressing these two miRNAs in LX-2 cells and found that overexpression of miRNA-150 and miRNA-194 resulted in a significant inhibition of c-myb and rac 1 expression, respectively. We conclude that both miRNA-150 and miRNA-194 inhibit HSC activation and ECM production, at least in part, via inhibition of c-myb and rac 1 expression. c-myb; microRNA-150; microRNA-194; rac 1

Background: MicroRNAs (miRNAs) have emerged as novel genetic regulators of cell functions such as proliferation, apoptosis and cancer. Aims: The aim of this study was to evaluate the role of a specific miRNA in modulating hepatic cell functions. Methods: C57Bl/6 mice were administered anti-fas receptor antibodies to induce liver cell apoptosis. miRNAs were purified from the liver tissue and evaluated using an miRNA microarray. The role of miRNA-491_5p, which was overexpressed in the model, in modulating hepatic cell functions was evaluated. miRNA-491_5p was overexpressed in Hep G2 cells, followed by the addition of tumour necrosis factor (TNF)-α, and induction of apoptosis as well as genes involved in apoptosis pathways were evaluated. The effect of miRNA-491_5p target genes on apoptosis was also analysed by inhibiting their expression by siRNA-induced gene silencing. Results: Upregulation of miRNA-491_5p was found in a high-dose anti-fas receptor antibody group. Overexpression of microRNA-491_5p sensitized Hep G2 cells for TNF-α-induced apoptosis, and also caused an inhibition of α-fetoprotein, (AFP), heat shock protein-90 (hsp-90) and nuclear factor-κB (NF-κB). Overexpression of miRNA-491_5p or inhibition of AFP and hsp-90 resulted in an increased apoptosis in TNF-α-treated Hep G2 cells. Conclusions: One of the miRNAs that is associated with the acute liver injury mouse model, miRNA-491_5p, sensitizes Hep G2 cells for TNF-α-induced apoptosis, at least in part, by inhibiting AFP, hsp-90 and NF-κB. [ABSTRACT FROM AUTHOR]

Hepatitis B Virus is a ds-DNA Virus, responsible for hepatocellular carcinoma (HCC), liver cirrhosis, fibrosis and a large number of mortality worldwide. HBV modulates many cellular factors for its replication and survival in host cell. Reactive oxygen species (ROS) theatre produced in the host cells during HBV infection was considered to inhibit the cellular antioxidants and Sirt-1 expression. However, the exact molecular mechanisms involved in the ROS-induced HBV replication has been not known. HepG2.2.15 cells (Hep G2 cells expressing HBV genome stably) werewere treated with the NAC (20 μm) and Sirt-1 inhibitor Butyrate (5mM) overnight. Western blotting was performed for the proteins Sirt-1, HBx, p-akt, akt, pmTOR, mTOR, Beclin-1, LC- 3, ATG5, and ?-actin using specific primary antibodies, followed by secondary antibodies and subsequent detection using ECL reagent. Analysis of ROS was performed using the H2-DCFDA in fluoresce microscopy. Autophagy assay was done using the Cyto-ID autophagy detection kit. Determination of the HBsAg was performed by ELISA and HBV-DNA was analysed using the Real-Time PCR method. HBV infection increased the ROS production and formation of autophagic bodies were observed in the cells. Addition of the NAC (antioxidant) inhabited both the autophagy and ROS production in HepG2.2.1.5 cells via modulation of the Beclin-1, LC-3 and ATG-5 expression. HBV transfection also induced the Sirt-1 expression which was inhibited by the addition of the butyrate and sirt-1 Si-RNA. Inhibition of the Sirt-1 expression by butyrate or Si-RNA inhibited the viral replication and HBV-induced autophagy. Furthermore, inhibition of Sirt-1 also lead to over-expression of the Actylated-P53, which in turn inhibited the cell proliferation in HBV-infected cells. In this present study we have shown that HBV infection Leads to the over-expression of Sirt- 1, which was be inhibited by butyrate treatment. These data may provide a possibility for the use of butyrate in therapeutic applications. [ABSTRACT FROM AUTHOR]

Introduction and Objectives: Metabolic dysfunction-associated steatotic liver disease (MASLD) is one of the primary causes of chronic liver disease and may lead to liver cirrhosis and hepatocellular carcinoma. Recent reports suggested that DEAD-box RNA helicase (DDX3) acts as a sensor of free fat accumulation and may modulate the pathogenesis via miRNAs. Hence, we hypothesized that DDX3 might modulate MASLD progression via miRNA-141-mediated inhibition of Sirt-1 and autophagy., Materials and Methods: RNA and total protein were isolated from free fatty acid-treated HepG2 cells or CDAA-fed C57BL/6 mice (6 mice per group) for 6, 18, 32, or 54 weeks. The cells were transfected with DDX3 or miR-141 or siRNA to DDX3, and Western blots for autophagy markers were performed., Results: The FFAs induced the DDX3 and miRNA-141 expression, while downregulating Sirt-1, beclin-1, Atg7, and LC3-II. Overexpression of DDX3 resulted in increased miRNA-141. Overexpression of DDX3 or miRNA-141 downregulated Sirt-1 expression and autophagy marker proteins, while these effects were reversed with siRNA to DDX3. The expression of both DDX3 and miRNA-141 was significantly increased, while autophagy markers were downregulated in CDAA-fed mice., Conclusions: These results confirmed that FFA-induced DDX3 induced the expression of miRNA-141, which in turn targeted Sirt-1 and decreased autophagy., Competing Interests: Declaration of interests None., (Copyright © 2024 Fundación Clínica Médica Sur, A.C. Published by Elsevier España, S.L.U. All rights reserved.)

Background: MicroRNAs (miRNAs) have emerged as novel genetic regulators of cell functions such as proliferation, apoptosis and cancer., Aims: The aim of this study was to evaluate the role of a specific miRNA in modulating hepatic cell functions., Methods: C57Bl/6 mice were administered anti-fas receptor antibodies to induce liver cell apoptosis. miRNAs were purified from the liver tissue and evaluated using an miRNA microarray. The role of miRNA-491&#95;5p, which was overexpressed in the model, in modulating hepatic cell functions was evaluated. miRNA-491&#95;5p was overexpressed in Hep G2 cells, followed by the addition of tumour necrosis factor (TNF)-alpha, and induction of apoptosis as well as genes involved in apoptosis pathways were evaluated. The effect of miRNA-491&#95;5p target genes on apoptosis was also analysed by inhibiting their expression by siRNA-induced gene silencing., Results: Upregulation of miRNA-491&#95;5p was found in a high-dose anti-fas receptor antibody group. Overexpression of microRNA-491&#95;5p sensitized Hep G2 cells for TNF-alpha-induced apoptosis, and also caused an inhibition of alpha-fetoprotein, (AFP), heat shock protein-90 (hsp-90) and nuclear factor-kappaB (NF-kappaB). Overexpression of miRNA-491&#95;5p or inhibition of AFP and hsp-90 resulted in an increased apoptosis in TNF-alpha-treated Hep G2 cells., Conclusions: One of the miRNAs that is associated with the acute liver injury mouse model, miRNA-491&#95;5p, sensitizes Hep G2 cells for TNF-alpha-induced apoptosis, at least in part, by inhibiting AFP, hsp-90 and NF-kappaB.