title: Identification of Glypican3 as a novel GLUT4-binding protein.
abstract: Insulin stimulates glucose uptake in fat and muscle primarily by stimulating the translocation of vesicles containing facilitative glucose transporters, GLUT4, from intracellular compartments to the plasma membrane. Although cell surface externalization of GLUT4 is critical for glucose transport, the mechanism regulating cell surface GLUT4 remains unknown. Using a yeast two-hybrid screening system, we have screened GLUT4-binding proteins, and identified a novel glycosyl phosphatidyl inositol (GPI)-linked proteoglycan, Glypican3 (GPC3). We confirmed their interaction using immunoprecipitation and a GST pull-down assay. We also revealed that GPC3 and GLUT4 to co-localized at the plasma membrane, using immunofluorescent microscopy. Furthermore, we observed that glucose uptake in GPC3-overexpressing adipocytes was increased by 30% as compared to control cells. These findings suggest that GPC3 may play roles in glucose transport through GLUT4.
authors.affiliation: Division of Endocrinology, Metabolism, Hematological Sciences and Therapeutics, Department of Bio-Signal Analysis, Yamaguchi University Graduate School of Medicine, 1-1-1 Minami-Kogushi, Ube, Yamaguchi, Japan.
authors.forename: Akihiko
authors.initials: A
authors.lastname: Taguchi
authors.forename: Masahiro
authors.initials: M
authors.lastname: Emoto
authors.forename: Shigeru
authors.initials: S
authors.lastname: Okuya
authors.forename: Naofumi
authors.initials: N
authors.lastname: Fukuda
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Nakamori
authors.forename: Mutsuko
authors.initials: M
authors.lastname: Miyazaki
authors.forename: Sachiko
authors.initials: S
authors.lastname: Miyamoto
authors.forename: Katsuya
authors.initials: K
authors.lastname: Tanabe
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Aburatani
authors.forename: Yoshitomo
authors.initials: Y
authors.lastname: Oka
authors.forename: Yukio
authors.initials: Y
authors.lastname: Tanizawa
mesh_terms: D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D005947:Glucose / Q000378:metabolism*; D051275:Glucose Transporter Type 4 / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D053673:Glypicans / Q000032:analysis / Q000302:isolation & purification / Q000378:metabolism*; D006801:Humans; D047468:Immunoprecipitation; D007328:Insulin / Q000378:metabolism / Q000494:pharmacology; D051379:Mice; D051381:Rats; D020798:Two-Hybrid System Techniques
chemical_list: D051275:Glucose Transporter Type 4; D053673:Glypicans; D007328:Insulin; D005947:Glucose