Project description:Background & Aims: Rapid induction of beta-PDGF receptor (beta-PDGFR) is a core feature of hepatic stellate cell activation, the hallmark of liver fibrogenesis. However, biological consequences of the induction are not well characterized. We aimed to determine the involvement of beta-PDGFR-mediated molecular pathway activation on hepatic stellate cells in liver injury, fibrogenesis, and carcinogenesis in vivo. Methods: Loss and constitutive activation of beta-PDGFR were assessed in mouse models with either a stellate cell-specific beta-PDGFR knockout or the expression of an autoactivating mutation respectively. Liver injury and fibrosis were induced in two mechanistically distinct models: carbontetrachloride (CCl4) treatment and ligation of the common bile duct. Hepatocarcinogenesis with underlying liver injury/fibrosis was assessed by a single dose of diethylnitrosamine (DEN) followed by repeated injections of CCl4. Genome-wide expression profiling was performed isolated stellate cells from these models to determine deregulated pathways. Results: Depletion of beta-PDGFR in hepatic stellate cells led to decreased histological liver injury, serum transaminases, collagen alpha 1(I) and alpha smooth muscle actin expression, and collagen deposition. Stellate cell proliferation was significantly reduced after acute hepatic injury in vivo. In contrast, autoactivation of beta-PDGFR in stellate cells accelerated liver fibrosis, most prominently after 6 weeks of CCl4 induced injury. There was no difference in development of DEN-induced pre-neoplastic loci according to the status of beta-PDGFR. Conclusions: Depletion of beta-PDGFR in hepatic stellate cells attenuated the development of liver injury, fibrosis, and stellate cell proliferation in multiple animal models, whereas the constitutive activation of beta-PDGFR enhanced fibrosis. However, manipulation of beta-PDGFR alone did not reduce development of dysplastic nodules. These findings indicate that titration of receptor beta-PDGFR expression on stellate cells parallels fibrosis and injury, but may not impact the development of hepatic neoplasia alone. Hepatic stellate cells were isolated from liver of beta-PDGFR-wild-type or knockout mice, and treated with beta-PDGF ligand or vehicle control.

Project description:Background: Increased Galectin 3-binding protein (Lgals3bp) serum levels have been used to assess hepatic fibrosis stages and the severity of hepatocellular carcinoma (HCC). Considering the crucial role of transforming growth factor-β1 (TGF-β1) in the emergence of these diseases, the present study tested the hypothesis that Lgals3bp regulates the TGF-β1 signaling pathway. Methods: The expression levels of Lgals3bp and TGF-β1 were analyzed in patients with non-alcoholic steatohepatitis (NASH) and HCC. Multiple omics techniques, such as RNA-sequencing, transposase-accessible chromatin-sequencing assay, and liquid chromatography-tandem mass spectrometry proteomics, were used to identify the regulatory mechanisms for the Lgals3bp-TGF-β1 axis. Moreover, the effects of altered TGF-β1 signaling in chronic inflammatory conditions were investigated in conditional Lgals3bp-knockin and Lgals3bp-knockout mice. Results: In patients with NASH and HCC, the levels of Lgals3bp and TGF-β1 exhibited positive correlations. Stimulation of Lgals3bp by the inflammatory cytokine interferon α in HCC cells or ectopic overexpression of Lgals3bp in hepatocytes promoted the expression levels of TGFB1. Aggravated fibrosis was observed in the livers of hepatocyte-specific Lgals3bp knock-in mice, with increased TGF-β1 levels. Lgals3bp directly bound to and assembled integrin αV, an integral mediator required for releasing active TGF-β1 from extracellular latent complex with the rearranged F-actin cytoskeleton. The released TGF-β1 activated JunB transcription factor, which in turn promoted the TGF-β1 positive feedback loop. Lgals3bp deletion in the hepatocytes downregulated TGF-β1 signaling and CCl4 induced fibrosis. Finally, Lgals3bp depletion hindered hepatocarcinogenesis by limiting the availability of fibrogenic TGF-β1. Conclusion: Lgals3bp plays a crucial role in hepatic fibrosis and carcinogenesis by controlling the TGF-β1 signaling pathway, making it a promising therapeutic target in TGF-β1-related diseases.

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TGF-β1/p65/MAT2A: a novel pathway involved in the regulation of intracellular SAM and liver fibrogenesis - Part1

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TGF-β1/p65/MAT2A pathway regulates liver fibrogenesis via intracellular SAM.

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