Defining the mechanism of galectin-3–mediated TGF-β1 activation and its role in lung fibrosis

Calver, Jessica F.; Parmar, Nimesh R.; Harris, Gemma; Lithgo, Ryan M.; Stylianou, Panayiota; Zetterberg, Fredrik R.; Gooptu, Bibek; Mackinnon, Alison C.; Carr, Stephen B.; Borthwick, Lee A.; Scott, David J.; Stewart, Iain D.; Slack, Robert J.; Jenkins, R. Gisli; John, Alison E.

Abstract

Integrin-mediated activation of the profibrotic mediator transforming growth factor-β1 (TGF-β1), plays a critical role in idiopathic pulmonary fibrosis (IPF) pathogenesis. Galectin-3 is believed to contribute to the pathological wound healing seen in IPF, although its mechanism of action is not precisely defined. We hypothesized that galectin-3 potentiates TGF-β1 activation and/or signaling in the lung to promote fibrogenesis. We show that galectin-3 induces TGF-β1 activation in human lung fibroblasts (HLFs) and specifically that extracellular galectin-3 promotes oleoyl-L-α-lysophosphatidic acid sodium salt–induced integrin-mediated TGF-β1 activation. Surface plasmon resonance analysis confirmed that galectin-3 binds to αv integrins, αvβ1, αvβ5, and αvβ6, and to the TGFβRII subunit in a glycosylation-dependent manner. This binding is heterogeneous and not a 1:1 binding stoichiometry. Binding interactions were blocked by small molecule inhibitors of galectin-3, which target the carbohydrate recognition domain. Galectin-3 binding to β1 integrin was validated in vitro by coimmunoprecipitation in HLFs. Proximity ligation assays indicated that galectin-3 and β1 integrin colocalize closely (≤40 nm) on the cell surface and that colocalization is increased by TGF-β1 treatment and blocked by galectin-3 inhibitors. In the absence of TGF-β1 stimulation, colocalization was detectable only in HLFs from IPF patients, suggesting the proteins are inherently more closely associated in the disease state. Galectin-3 inhibitor treatment of precision cut lung slices from IPF patients’ reduced Col1a1, TIMP1, and hyaluronan secretion to a similar degree as TGF-β type I receptor inhibitor. These data suggest that galectin-3 promotes TGF-β1 signaling and may induce fibrogenesis by interacting directly with components of the TGF-β1 signaling cascade.

Citation

Calver, J. F., Parmar, N. R., Harris, G., Lithgo, R. M., Stylianou, P., Zetterberg, F. R., Gooptu, B., Mackinnon, A. C., Carr, S. B., Borthwick, L. A., Scott, D. J., Stewart, I. D., Slack, R. J., Jenkins, R. G., & John, A. E. (2024). Defining the mechanism of galectin-3–mediated TGF-β1 activation and its role in lung fibrosis. Journal of Biological Chemistry, 300(6), Article 107300. https://doi.org/10.1016/j.jbc.2024.107300

• Journal Article Type: Article
• Acceptance Date: Apr 11, 2024
• Online Publication Date: Apr 17, 2024
• Publication Date: Jun 1, 2024
• Deposit Date: Mar 7, 2025
• Publicly Available Date: Mar 11, 2025
• Journal: Journal of Biological Chemistry
• Print ISSN: 0021-9258
• Electronic ISSN: 1083-351X
• Publisher: American Society for Biochemistry and Molecular Biology
• Peer Reviewed: Peer Reviewed
• Volume: 300
• Issue: 6
• Article Number: 107300
• DOI: https://doi.org/10.1016/j.jbc.2024.107300
• Keywords: pulmonary fibrosis, fibroblast, transforming growth factor beta (TGF-β), integrin, galectin
• Public URL: https://nottingham-repository.worktribe.com/output/34093486
• Publisher URL: https://www.jbc.org/article/S0021-9258(24)01801-5/fulltext
• Additional Information: This article is maintained by: Elsevier; Article Title: Defining the mechanism of galectin-3–mediated TGF-β1 activation and its role in lung fibrosis; Journal Title: Journal of Biological Chemistry; CrossRef DOI link to publisher maintained version: https://doi.org/10.1016/j.jbc.2024.107300; Content Type: article; Copyright: © 2024 The Authors. Published by Elsevier Inc on behalf of American Society for Biochemistry and Molecular Biology.