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:Background & aimsAutophagy plays a crucial role in hepatic homeostasis and its deregulation has been associated with chronic liver disease. However, the effect of autophagy on the release of fibrogenic extracellular vesicles (EVs) by platelet-derived growth factor (PDGF)-stimulated hepatic stellate cells (HSCs) remains unknown. Herein, we aimed to elucidate the role of autophagy, specifically relating to fibrogenic EV release, in fibrosis.MethodsIn vitro experiments were conducted in primary human and murine HSCs as well as LX2 cells. Small EVs were purified by differential ultracentrifugation. Carbon tetrachloride (CCl4) or bile duct ligation (BDL) were used to induce fibrosis in our mouse model. Liver lysates from patients with cirrhosis or healthy controls were compared by RNA sequencing.ResultsIn vitro, PDGF and its downstream molecule SHP2 (Src homology 2-containing protein tyrosine phosphatase 2) inhibited autophagy and increased HSC-derived EV release. We used this PDGF/SHP2 model to further investigate how autophagy affects fibrogenic EV release. RNA sequencing identified an mTOR (mammalian target of rapamycin) signaling molecule that was regulated by SHP2 and PDGF. Disruption of mTOR signaling abolished PDGF-dependent EV release. Activation of mTOR signaling induced the release of multivesicular body-derived exosomes (by inhibiting autophagy) and microvesicles (by activating ROCK1 signaling). These mTOR-dependent EVs promoted in vitro HSC migration. To assess the importance of this mechanism in vivo, SHP2 was selectively deleted in HSCs, which attenuated CCl4- or BDL-induced liver fibrosis. Furthermore, in the CCl4 model, mice receiving circulating EVs derived from mice with HSC-specific Shp2 deletion had less fibrosis than mice receiving EVs from control mice. Correspondingly, SHP2 was upregulated in patients with liver cirrhosis.ConclusionThese results demonstrate that autophagy in HSCs attenuates liver fibrosis by inhibiting the release of fibrogenic EVs.Lay summaryDuring liver fibrosis and cirrhosis, activated hepatic stellate cells (HSCs) are the key cell type responsible for fibrotic tissue deposition. Recently, we demonstrated that activated HSCs release nano-sized vesicles enriched with fibrogenic proteins. In the current study, we unveil the mechanism by which these fibrogenic vesicles are released, moving a step closer to the long-term goal of therapeutically targeting this process.

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ASPP2 Inhibits the Profibrotic Effects of Transforming Growth Factor-?1 in Hepatic Stellate Cells by Reducing Autophagy.

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ASPP2 Inhibits the Profibrotic Effects of Transforming Growth Factor-β1 in Hepatic Stellate Cells by Reducing Autophagy.

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