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Downregulation of the Wnt antagonist Dkk2 links loss of Sept4 and myofibroblastic transformation of hepatic stellate cells

ABSTRACT: Background/Aims: Sept4, a subunit of the septin cytoskeleton specifically expressed in quiescent hepatic stellate cells (HSCs), is downregulated through transdifferentiation to fibrogenic and contractile myofibroblastic cells. Since Sept4−/− mice are prone to liver fibrosis, we examined the unknown molecular network underlying liver fibrosis by probing the association between loss of Sept4 and accelerated transdifferentiation of HSCs. Methods: We compared the transcriptomes of Sept4+/+ and Sept4−/− HSCs by differential DNA microarray analysis and quantitative RT-PCR. Based on reduced dickkopf2 (Dkk2) gene expression in Sept4−/− HSCs, we tested whether supplementing Dkk2 could suppress myofibroblastic transformation of Sept4−/− HSCs. We used a lymphoid enhancer-binding factor/transcription factor-luciferase reporter assay to test whether Dkk2 can exert anti-fibrotic effects by interfering with the canonical Wnt pathway. Results: We observed consistent upregulation of Dkk2 in primary cultured HSCs and in a carbon tetrachloride hepatitis model in mice, which decreased with loss of Sept4. Supplementing Dkk2 suppressed the induction of pro-fibrotic genes (α-smooth muscle actin and 2 collagen genes) and induced an anti-fibrotic gene (Smad7) in Sept4−/− HSCs. In human liver specimens with inflammation and fibrosis, Dkk2 immunoreactivity appeared to be positively correlated with the degree of fibrotic changes. Conclusions: Pro-fibrotic transformation of HSCs through the loss of Sept4 is partly due to reduced expression of Dkk2 and its homologues, and the resulting disinhibition of the canonical Wnt pathway.

ORGANISM(S): Mus musculus

PROVIDER: GSE24588 | GEO | 2012/06/03

SECONDARY ACCESSION(S): PRJNA132373

REPOSITORIES: GEO

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Downregulation of the Wnt antagonist Dkk2 links loss of Sept4 and myofibroblastic transformation of hepatic stellate cells

Project description:Background/Aims: Sept4, a subunit of the septin cytoskeleton specifically expressed in quiescent hepatic stellate cells (HSCs), is downregulated through transdifferentiation to fibrogenic and contractile myofibroblastic cells. Since Sept4?/? mice are prone to liver fibrosis, we examined the unknown molecular network underlying liver fibrosis by probing the association between loss of Sept4 and accelerated transdifferentiation of HSCs. Methods: We compared the transcriptomes of Sept4+/+ and Sept4?/? HSCs by differential DNA microarray analysis and quantitative RT-PCR. Based on reduced dickkopf2 (Dkk2) gene expression in Sept4?/? HSCs, we tested whether supplementing Dkk2 could suppress myofibroblastic transformation of Sept4?/? HSCs. We used a lymphoid enhancer-binding factor/transcription factor-luciferase reporter assay to test whether Dkk2 can exert anti-fibrotic effects by interfering with the canonical Wnt pathway. Results: We observed consistent upregulation of Dkk2 in primary cultured HSCs and in a carbon tetrachloride hepatitis model in mice, which decreased with loss of Sept4. Supplementing Dkk2 suppressed the induction of pro-fibrotic genes (?-smooth muscle actin and 2 collagen genes) and induced an anti-fibrotic gene (Smad7) in Sept4?/? HSCs. In human liver specimens with inflammation and fibrosis, Dkk2 immunoreactivity appeared to be positively correlated with the degree of fibrotic changes. Conclusions: Pro-fibrotic transformation of HSCs through the loss of Sept4 is partly due to reduced expression of Dkk2 and its homologues, and the resulting disinhibition of the canonical Wnt pathway. We induced Liver Cirrhosis to SEPT4-KO or wild type mouse by CCl4, and examined mRNA expression profiling in hepatic stellate cell of these mouse.

2012-06-02 | E-GEOD-24588 | biostudies-arrayexpress

Investigation of hepatic stellate cell proteomics during activa-tion with fetal bovine serum

Project description:Hepatic stellate cells (HSCs) are the major driving factor in liver fibrosis. Upon liver inflammation caused by alcohol abuse and/or a fatty liver, HSCs transform from a quiescent- into a proliferating, fibrotic phenotype. We study this transformation termed “activation”, using state of the art TIMS-TOF mass spectrometry proteomics, as well as phenotype analysis of the immortalized LX-2 HSC cell line. In our work we employ a simple, yet reliable model of HSC activation via an in-crease in growth media serum concentration (serum activation). Protein network analysis of ac-tivated LX 2 cells reveals an increase in the production of ribosomal proteins and proteins related to migration. Interestingly, we could also observe a decrease in the expression of lipogenic pro-teins and a loss of cytosolic lipid droplets during activation. Especially the downregulation of proteins associated with cholesterol biosynthesis might be a promising target for further study. This work provides an update on HSC activation characteristics using contemporary proteomic and bioinformatic analysis and presents an accessible model for HSC activation.

2022-02-14 | PXD029121 | Pride

A master cistromic circuit governing hepatic fibrogenesis [ChIP-seq]

Project description:Liver fibrosis is a reversible wound-healing response to liver injury and hepatic stellate cells (HSCs) are central cellular players that mediate hepatic fibrogenesis. However, the molecular mechanisms that govern this process remain unclear. Here, we reveal a novel cistromic circuit in HSCs comprising the vitamin D receptor (VDR) and SMAD transcription factors that restrains the intensity of hepatic fibrogenesis. Ligand-activated VDR suppresses TGFβ1-induced pro-fibrotic gene expression in HSCs. Administration of a vitamin D analogue, calcipotriol, diminishes the fibrotic response in a mouse model of liver fibrosis, while VDR knockout mice spontaneous develop extensive hepatic fibrosis by age 6 months. Using ChIP-Seq, we find that the anti-fibrotic properties of VDR are due to crosstalk with SMAD, mediated by their co-occupancy of DNA-binding sites on pro-fibrotic genes. Specifically, SMAD binding potentiates local chromatin accessibility to enhance VDR recruitment at the same cis-regulatory elements, which reciprocally antagonizes the interaction between SMAD3 and chromatin and limits the assembly of transcriptional activation complexes at fibrotic genes, a process that is enhanced by the presence of VDR agonists. These results not only establish this coordinated VDR/SMAD cistromic circuit as a master regulator of hepatic fibrogenesis, but also support VDR as a potential drug target to ameliorate liver fibrosis. Identification of VDR, SMAD3 and H3 binding sites in human stellate LX2 cells that were pre-treated with calcipotriol (100nM) for 16 hrs (where calcipotriol treatment is indicated) followed by incubation of calcipotriol (100nM) or TGFβ1 (1ng/ml) for another 4 hours (where indicated).

2013-04-29 | E-GEOD-38103 | biostudies-arrayexpress

Glycolysis in hepatic stellate cells coordinates fibrogenic extracellular vesicle release in a spatial manner to amplify liver fibrosis

Project description:Liver fibrosis is characterized by the activation of hepatic stellate cells (HSCs) and the release of fibrogenic nano-sized extracellular vesicles (EVs). Activated HSCs increase their glucose metabolism via glycolysis to satisfy high energy demands. Nevertheless, the mechanism of how glycolysis in HSCs coordinates fibrosis amplification in the fibrogenic zones in the liver is elusive and is the scope of this study. Single cell RNA sequencing (scRNAseq) and bulk RNAseq demonstrated that several glycolysis enzymes, including hexokinase 2 (HK2), were upregulated in activated HSCs. HSC-selective glycolysis-deficient mice (HK2ΔHSC) showed abrogated CCl4-mediated fibrosis as compared to littermate controls (HK2fl/fl). Spatial transcriptomics revealed an upregulation of several EV-related pathways in the fibrotic pericentral zone during liver fibrosis in control HK2fl/fl mice. However, glycolysis-deficient HK2ΔHSC mice showed downregulation of these EV-related pathways in the pericentral zone. Consistently, induction of glycolysis in HSCs in vitro, either by glucose or platelet-derived growth factor B (PDGF), upregulated the expression of several extracellular vesicle (EV)-related genes, including RAB31. Glycolysis in HSCs epigenetically enhanced RAB31 expression through histone-3 lysine-9 acetylation (H3K9ac) on the promoter region, leading to increased EV release. Functionally, glycolysis-dependent EVs were enriched with fibrogenic molecules and increased the expression of fibrotic markers in recipient HSCs. Finally, EVs derived from glycolysis-deficient HK2ΔHSC mice abrogated liver fibrosis amplification as compared to EVs derived from littermate control HK2fl/fl mice. In summary, glycolysis in HSCs amplifies liver fibrosis by promoting fibrogenic EV release in the pericentral fibrotic regions in the liver.

2024-03-20 | GSE259363 | GEO

LIX1L stabilization of CCL20 promotes fibrosis

Project description:Expression of LIX1L is increased in fibrotic livers and associated with liver fibrosis stage. We investigated whether increased LIX1L expression promotes Hepatic stellate cells (HSCs) activation and liver fibrosis progression by interacting with Chemokine signaling pathway.

2019-06-22 | GSE133121 | GEO

Parathyroid Hormone Receptor-1 Signaling Aggravates Hepatic Fibrosis through Upregulating cAMP Response Element Binding Protein-Like 2 (human)

Project description:Background & Aims Parathyroid hormone receptor-1 (PTH1R) is a class B G protein-coupled receptor central to skeletal development, bone turnover, and calcium homeostasis. However, the role of PTH1R signaling in liver fibrosis is largely unknown. Here, the role of PTH1R signaling in the activation of hepatic stellate cells (HSCs) and hepatic fibrosis was examined. Approach & Results PTH1R was highly expressed in activated HSCs and fibrotic liver by using human liver specimens or carbon tetrachloride (CCl4)-treated or methionine and choline-deficient diet (MCD)-fed C57/BL6 mice. The mRNA level of hepatic PTH1R was positively correlated to α-smooth muscle actin (α-SMA) in patients with liver cirrhosis. Mice with HSCs-specific PTH1R deletion were protected from CCl4, MCD, or western diet plus low-dose CCl4-induced liver fibrosis. Conversely, parathyroid hormone (PTH) aggravated liver fibrosis in CCl4-treated mice. Mouse primary HSCs and LX2 cell lines were used for in vitro experiments. Molecular analyses by luciferase reporter assays and chromatin-immunoprecipitation assays in combination with mRNA sequencing in HSCs revealed that cAMP response element-binding protein-like 2 (Crebl2), a novel regulator in HSCs treated by PTH that interacted with Mothers against decapentaplegic homolog 3 (SMAD3) and increased the transcription of transforming growth factor β (TGFβ) in activating HSCs and collagen deposition. In agreement, HSCs-specific Crebl2 deletion ameliorated PTH-induced liver fibrosis in CCl4-treated mice. Conclusions In both mouse and human models, we found that PTH1R was highly expressed in activated HSCs and fibrotic liver. PTH1R signaling regulated collagen production in the HSCs via Crebl2/SMAD3/TGFβ regulatory circuits. Blockade of PTH1R signaling in HSCs might help mitigate the development of liver fibrosis.

2023-03-29 | GSE227902 | GEO

Parathyroid Hormone Receptor-1 Signaling Aggravates Hepatic Fibrosis through Upregulating cAMP Response Element Binding Protein-Like 2 (mouse)

2023-03-29 | GSE227901 | GEO

Super-Enhancer-mediated Control of Liver Fibrosis by BET Bromodomain Proteins

Project description:Here, we investigate the role of enhancers in myofibroblasts, a cell type that dominates the pathogenesis and progression of tissue fibrosis. We reveal that bromodomain and extra-terminal family members (BETs), an important group of epigenetic readers, are critical for super-enhancer-mediated pro-fibrotic gene expression in hepatic stellate cells (HSCs, lipid-containing liver-specific pericytes), upon activation during liver fibrogenesis give rise to myofibroblasts2-4. We observe significantly enriched localization of BETs to hundreds of super-enhancers associated with genes involved in multiple pro-fibrotic pathways. This unique loading pattern consequentially serves as a molecular mechanism by which BETs modulate pro-fibrotic gene expression in myofibroblasts. Strikingly, suppression of BET-enhancer interaction using small-molecule inhibitors such as JQ1 dramatically blocks activation of HSCs into myofibroblasts and significantly compromises the proliferation of activated HSCs. Identification of BRD2, BRD3, BRD4, PolII, PolIIs2p and PolIIs5p binding sites in human stellate LX2 cells that were treated with DMSO (0.1%) or JQ1 (500nM) for 16 hrs.

2015-12-11 | E-GEOD-58680 | biostudies-arrayexpress

Genome wide mapping of long noncoding (lnc) RNAs in hepatic stellate cells

Project description:Hepatic stellate cells are the primary cell type responsible for development of fibrosis in chronic liver disease. We used directional RNA sequencing (RNA-seq) and chromatin immunoprecipitation and sequencing (ChIP-seq) to identify the lncRNAs expressed in human HSCs. We also identified the lncRNAs that change in expression with differentiation of nonfibrotic quiescent HSCs into fibrotic HSC myofibroblasts and those that are regulated by TGF-beta signaling. ChIP-seq was also performed to identify DNA regions occupied by H3K27ac to define super-enhancers in HSC myofibroblasts. This study identified lncRNAs expressed HSCs that may regulate fibrosis. Analysis of genome-wide lncRNA expression using RNA-seq and ChiP-seq in human HSCs under four different conditions

2016-03-23 | E-GEOD-68108 | biostudies-arrayexpress

A master cistromic circuit governing hepatic fibrogenesis [ChIP-seq]

2013-04-29 | GSE38103 | GEO

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