title: Tyrosine kinase activity of epidermal growth factor receptor is regulated by GM3 binding through carbohydrate to carbohydrate interactions.
abstract: Epidermal growth factor receptor (EGFR), an N-glycosylated transmembrane protein with an intracellular kinase domain, undergoes dimerization by ligand binding resulting in activation of the kinase domain and phosphorylation. Ganglioside GM3 containing sialyllactose inhibits the tyrosine kinase activity of EGFR through carbohydrate to carbohydrate interactions (CCI) between N-glycans with GlcNAc termini on EGFR and oligosaccharides on GM3. In this study, we provide further evidence for CCI between EGFR and GM3. (i) In vitro and in situ, the inhibitory effect of GM3 on EGFR tyrosine kinase was much higher in A431 cells upon exposure of the GlcNAc termini of the N-glycans to glycosidase treatment (neuraminidase and beta-galactosidase) than in untreated A431 cells. Furthermore, the GM3-mediated inhibition was abrogated by co-incubation with N-glycan containing terminal GlcNAc. (ii) In situ, inhibition of EGFR phosphorylation by GM3 was not observed in alpha-mannosidase IB (ManIB)-knocked down A431 cells that accumulate high mannose-type N-glycans. (iii) EGFR binding to GM3 was enhanced in glycosidase-treated cells that accumulated GlcNAc termini, whereas GM3 did not bind to EGFR from ManIB-knocked down cells that accumulated high mannose-type N-glycans. These results indicate that GM3-mediated inhibition of EGFR phosphorylation is caused by interaction of GM3 with GlcNAc-terminated N-glycan on EGFR.
authors.affiliation: Health Technology Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Takamatsu, Kagawa 761-0395, Japan.
authors.forename: Nagako
authors.initials: N
authors.lastname: Kawashima
authors.forename: Seon-Joo
authors.initials: SJ
authors.lastname: Yoon
authors.forename: Kohji
authors.initials: K
authors.lastname: Itoh
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Nakayama
mesh_terms: D000117:Acetylglucosamine / Q000378:metabolism / Q000494:pharmacology; D045744:Cell Line, Tumor; D066246:ErbB Receptors / Q000235:genetics / Q000378:metabolism*; D005679:G(M3) Ganglioside / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D010766:Phosphorylation / Q000187:drug effects / Q000502:physiology; D011485:Protein Binding / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000502:physiology
chemical_list: D005679:G(M3) Ganglioside; C512478:EGFR protein, human; D066246:ErbB Receptors; D000117:Acetylglucosamine