Identification of Glypican3 as a novel GLUT4-binding protein.
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.
Taguchi
Akihiko
A
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.
Emoto
Masahiro
M
Okuya
Shigeru
S
Fukuda
Naofumi
N
Nakamori
Yoshitaka
Y
Miyazaki
Mutsuko
M
Miyamoto
Sachiko
S
Tanabe
Katsuya
K
Aburatani
Hiroyuki
H
Oka
Yoshitomo
Y
Tanizawa
Yukio
Y
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
D051275:Glucose Transporter Type 4; D053673:Glypicans; D007328:Insulin; D005947:Glucose