title: Bisecting GlcNAc residues on laminin-332 down-regulate galectin-3-dependent keratinocyte motility.
abstract: Laminin-332 (Lm332; formerly laminin-5) is a basement membrane protein in the skin, which promotes cell motility in wound healing and cancer invasion. In a previous study, we reported that the introduction of bisecting GlcNAc into Lm332 (GnT-III-Lm332), catalyzed by N-acetylglucosaminyltransferase III (GnT-III), reduced cell migration (Kariya, Y., Kato, R., Itoh, S., Fukuda, T., Shibukawa, Y., Sanzen, N., Sekiguchi, K., Wada, Y., Kawasaki, N., and Gu, J. (2008) J. Biol. Chem. 283, 33036-33045). However, the underlying molecular mechanism by which GnT-III-Lm332 suppresses the normal biological functions of Lm332 remains to be elucidated. In this study, we show that galectin-3, which is a beta-galactoside-binding protein, strongly bound to unmodified Lm332 but not to GnT-III-Lm332 and that binding of galectin-3 was completely blocked by lactose. Exogenous galectin-3 significantly enhanced keratinocyte cell motility on control Lm332 but not on GnT-III-Lm332. A functional blocking antibody against galectin-3 inhibited Lm332-induced alpha3beta1 and alpha6beta4 integrin clustering and focal contact formation. Co-immunoprecipitation revealed that galectin-3 associated with both beta4 integrin and epidermal growth factor receptor, thereby cross-linking the two molecules. The associations were inhibited by either the presence of lactose or expression of GnT-III. Moreover, galectin-3 consistently enhanced ERK activation. Taken together, the results of this study are the first to clearly identify the molecular mechanism responsible for the inhibitory effects of GnT-III on extracellular matrix-integrin-meditated cell adhesion, migration, and signal transduction. The findings presented herein shed light on the importance of N-glycosylation-mediated supramolecular complex formation on the cell surface.
authors: Division of Regulatory Glycobiology, Institute of Molecular Biomembrane and Glycobiology, Tohoku Pharmaceutical University, Sendai, Miyagi 981-8558, Japan.
authors: Yoshinobu
authors: Y
authors: Kariya
authors: Chihiro
authors: C
authors: Kawamura
authors: Toshiki
authors: T
authors: Tabei
authors: Jianguo
authors: J
authors: Gu
mesh_terms: D000117:Acetylglucosamine / Q000737:chemistry*; D002448:Cell Adhesion; D002465:Cell Movement; D015536:Down-Regulation; D004789:Enzyme Activation; D066246:ErbB Receptors / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D037502:Galectin 3 / Q000378:metabolism*; D006801:Humans; D039201:Integrin alpha3beta1 / Q000378:metabolism; D039161:Integrin alpha6beta4 / Q000378:metabolism; D015603:Keratinocytes / Q000166:cytology*; D007797:Laminin / Q000737:chemistry*; D017351:N-Acetylglucosaminyltransferases / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D037502:Galectin 3; D039201:Integrin alpha3beta1; D039161:Integrin alpha6beta4; D007797:Laminin; D017351:N-Acetylglucosaminyltransferases; C054599:beta-1,4-mannosyl-glycoprotein beta-1,4-N-acetylglucosaminyltransferase; D066246:ErbB Receptors; D048049:Extracellular Signal-Regulated MAP Kinases; D000117:Acetylglucosamine