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.

Project description:Venkatraman2012 - Interplay between PLS and TSP1 in TGF-β1 activation The interplay between PLS (Plasmin) and TSP1 (Thrombospondin-1) in TGF-β1 (Transforming growth factor-β1)is shown using mathematical modelling and in vitro experimentents. This model is described in the article: Plasmin triggers a switch-like decrease in thrombospondin-dependent activation of TGF-β1. Venkatraman L, Chia SM, Narmada BC, White JK, Bhowmick SS, Forbes Dewey C Jr, So PT, Tucker-Kellogg L, Yu H. Biophys J. 2012 Sep 5;103(5):1060-8. Abstract: Transforming growth factor-β1 (TGF-β1) is a potent regulator of extracellular matrix production, wound healing, differentiation, and immune response, and is implicated in the progression of fibrotic diseases and cancer. Extracellular activation of TGF-β1 from its latent form provides spatiotemporal control over TGF-β1 signaling, but the current understanding of TGF-β1 activation does not emphasize cross talk between activators. Plasmin (PLS) and thrombospondin-1 (TSP1) have been studied individually as activators of TGF-β1, and in this work we used a systems-level approach with mathematical modeling and in vitro experiments to study the interplay between PLS and TSP1 in TGF-β1 activation. Simulations and steady-state analysis predicted a switch-like bistable transition between two levels of active TGF-β1, with an inverse correlation between PLS and TSP1. In particular, the model predicted that increasing PLS breaks a TSP1-TGF-β1 positive feedback loop and causes an unexpected net decrease in TGF-β1 activation. To test these predictions in vitro, we treated rat hepatocytes and hepatic stellate cells with PLS, which caused proteolytic cleavage of TSP1 and decreased activation of TGF-β1. The TGF-β1 activation levels showed a cooperative dose response, and a test of hysteresis in the cocultured cells validated that TGF-β1 activation is bistable. We conclude that switch-like behavior arises from natural competition between two distinct modes of TGF-β1 activation: a TSP1-mediated mode of high activation and a PLS-mediated mode of low activation. This switch suggests an explanation for the unexpected effects of the plasminogen activation system on TGF-β1 in fibrotic diseases in vivo, as well as novel prognostic and therapeutic approaches for diseases with TGF-β dysregulation. This model is hosted on BioModels Database and identified by: MODEL1303130000 . To cite BioModels Database, please use: BioModels Database: An enhanced, curated and annotated resource for published quantitative kinetic models . To the extent possible under law, all copyright and related or neighbouring rights to this encoded model have been dedicated to the public domain worldwide. Please refer to CC0 Public Domain Dedication for more information.

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A novel non-canonical signaling pathway mediates TGF-β1-induced glucocorticoid insensitivity in epithelial cells

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