Galectin Lattice Regulates Nutrition Sensor Functions in Pancreatic β Cells

Abstract

Recently, it has been elucidated that the lattice structure formed by complexes of galectins and N-glycans regulates expression and function of plasmalemmal glycoproteins, which is important for maintaining various homeostatic systems. We have previously revealed that the failure of N-glycosylation abolishes lattice formation and induces aberrant membrane sub-domain distribution of Glucose transporter 2 (GLUT2) in pancreatic β cells that consequently attenuates the cellular glucose uptake function. This results in the impairment of insulin secretion in pancreatic β cells in the disease process of diabetes. Although the biological significance of the formation of the galectin lattice is well recognized, the molecular regulatory mechanism of the localization and function of plasmalemmal glycoproteins has not been clarified. To address the question, we analyzed the component proteins of the galectin lattice complexes on pancreatic β cell surface and found that the lattice complexes were composed of Cationic amino acid transporter 3 (CAT3), Teneurin-3, Myosin-4, Actin, α-Tubulin, and GLUT2 at least. These results indicated that the galectin lattice forms clusters of plasmalemmal glycoproteins through galectin-N-glycan bindings and further suggested the presence of the common mechanism among the functional regulation of nutrition sensors in the insulin secretion of pancreatic β cells.