galectin3

Galectin-3 is a member of the galectin family of beta-galactoside–binding lectins. It is encoded by the LGALS3 gene in humans and is also known as Mac-2. Galectin-3 is a chimera-type galectin with a C-terminal carbohydrate recognition domain and an N-terminal domain that promotes oligomerization. It lacks a classical signal peptide, allowing it to be secreted by non-classical pathways and to function outside cells as well as inside.

Galectin-3 is widely expressed in many tissues and cell types, including macrophages, epithelial cells, fibroblasts, and endothelial cells. The protein binds to beta-galactoside-containing glycoconjugates and can cross-link glycoproteins, influencing cell adhesion, migration, and signaling. Its carbohydrate recognition domain interacts with various glycans in a calcium-independent manner, and the N-terminal domain enables multimerization that enhances lattice formation with ligands in the extracellular matrix.

Functionally, galectin-3 participates in immune regulation, inflammation, tissue repair, and fibrosis. It modulates macrophage activation, T-cell apoptosis, neutrophil function, and cytokine production, and it can influence tumor biology by affecting cell proliferation, survival, angiogenesis, and metastasis. Intracellularly, it participates in anti-apoptotic signaling and subcellular processes, while extracellularly it shapes cell–cell and cell–matrix interactions.

Clinical significance includes its utility as a biomarker in cardiovascular disease and fibrosis; elevated galectin-3 levels are associated with prognosis in heart failure and liver fibrosis. Therapeutically, galectin-3 inhibitors have been explored in clinical trials, with agents such as belapectin (GR-MD-02) studied for fibrotic diseases and cancer-related contexts.