Poster - #VH-52762 - Keywords: Galectin-3, O-GlcNAcylation, HBP

O-GlcNAcylation Regulates Galectin-3 Lattice Assembly by Integrating Galectin-3 Synthesis, Non-canonical Secretion, and Recycling

Mana Mohan Mukherjee, and John A. Hanover*
Cell Biochemistry Section, Laboratory of Cell and Molecular Biology, National Institute of Diabetes Digestive and Kidney Disease (NIDDK), NIH, Bethesda, MD, USA 20892

ABSTRACT:
Galectin-3, a β-galactoside-binding lectin, forms extracellular lattices that regulate membrane receptor dynamics and signal transduction. While galectin-3 secretion and surface presentation are known to be non-canonical, the upstream regulatory mechanisms that coordinate its trafficking and function are largely unknown. Here, we identify O-GlcNAcylation as a central metabolic sensor modulating galectin-3 trafficking and secretion and influencing its intracellular fate and extracellular function. We show that O-GlcNAc cycling modulates galectin-3 protein levels by influencing transcriptional output and post-translational stability. Furthermore, O-GlcNAcylation governs non-classical secretion of galectin-3 via a Golgi-bypass route and controls its recycling from the cell surface through endosomal compartments. Perturbation of O-GlcNAc transferase or hydrolase activity disrupts galectin-3 surface localization and impairs lattice formation, leading to altered receptor retention and signaling dynamics. Specifically, OGA deletion in mice or embryonic fibroblast cells elevates global O-GlcNAcylation. This results in transcriptional repression of galectin-3 mRNA, as determined by qPCR, along with reduction in intracellular galectin-3, confirmed through western blotting and confocal imaging. Additionally, ELISA analysis from the cell culture supernatant revealed a significant decrease in its extracellular secreted galectin-3. These findings identify O-GlcNAcylation as a master integrator of galectin-3 synthesis, secretion, and trafficking, revealing a nutrient-sensitive mechanism that couples cellular metabolism to lectin-mediated extracellular architecture. The widespread use of galectin-3 as a biomarker for human disease highlights the need for a more complete understanding of the role of O-GlcNAc in modulating galectin-3 expression and secretion.