Characterization of the role of the Rab GTPase-activating protein AS160 in insulin-regulated GLUT4 trafficking.
Insulin stimulates the translocation of the glucose transporter GLUT4 from intracellular vesicles to the plasma membrane. In the present study we have conducted a comprehensive proteomic analysis of affinity-purified GLUT4 vesicles from 3T3-L1 adipocytes to discover potential regulators of GLUT4 trafficking. In addition to previously identified components of GLUT4 storage vesicles including the insulin-regulated aminopeptidase insulin-regulated aminopeptidase and the vesicle soluble N-ethylmaleimide factor attachment protein (v-SNARE) VAMP2, we have identified three new Rab proteins, Rab10, Rab11, and Rab14, on GLUT4 vesicles. We have also found that the putative Rab GTPase-activating protein AS160 (Akt substrate of 160 kDa) is associated with GLUT4 vesicles in the basal state and dissociates in response to insulin. This association is likely to be mediated by the cytosolic tail of insulin-regulated aminopeptidase, which interacted both in vitro and in vivo with AS160. Consistent with an inhibitory role of AS160 in the basal state, reduced expression of AS160 in adipocytes using short hairpin RNA increased plasma membrane levels of GLUT4 in an insulin-independent manner. These findings support an important role for AS160 in the insulin regulated trafficking of GLUT4.
Larance
Mark
M
Diabetes and Obesity Program, Garvan Institute of Medical Research, Sydney, Australia.
Ramm
Georg
G
Stöckli
Jacqueline
J
van Dam
Ellen M
EM
Winata
Stephanie
S
Wasinger
Valerie
V
Simpson
Fiona
F
Graham
Michael
M
Junutula
Jagath R
JR
Guilhaus
Michael
M
James
David E
DE
D041721:3T3-L1 Cells; D017667:Adipocytes / Q000166:cytology / Q000378:metabolism; D000626:Aminopeptidases / Q000378:metabolism; D000818:Animals; D002460:Cell Line; D006224:Cricetinae; D010122:Cystinyl Aminopeptidase; D005347:Fibroblasts; D020690:GTPase-Activating Proteins / Q000235:genetics / Q000378:metabolism*; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D051275:Glucose Transporter Type 4 / Q000235:genetics / Q000378:metabolism*; D007328:Insulin / Q000494:pharmacology*; D051379:Mice; D021381:Protein Transport / Q000187:drug effects; D034622:RNA Interference; D022142:Secretory Vesicles / Q000378:metabolism
D020690:GTPase-Activating Proteins; D051275:Glucose Transporter Type 4; D007328:Insulin; C505647:Tbc1d4 protein, mouse; D000626:Aminopeptidases; D010122:Cystinyl Aminopeptidase; C105964:leucyl-cystinyl aminopeptidase