title: Mice with AS160/TBC1D4-Thr649Ala knockin mutation are glucose intolerant with reduced insulin sensitivity and altered GLUT4 trafficking.
abstract: AS160 has emerged as a key player in insulin-mediated glucose transport through controlling GLUT4 trafficking, which is thought to be regulated by insulin-stimulated phosphorylation of sites including the 14-3-3 binding phospho-Thr649 (equivalent to Thr642 in human AS160). To define physiological roles of AS160-Thr649 phosphorylation and 14-3-3 binding in glucose homeostasis, we substituted this residue by a nonphosphorylatable alanine by knockin mutation in mice. The mutant protein was expressed at normal levels, while insulin-stimulated AS160 binding to 14-3-3s was abolished in homozygous knockin mice. These animals displayed impaired glucose disposal and insulin sensitivity, which were associated with decreased glucose uptake in vivo. Insulin-stimulated glucose transport and cell surface GLUT4 content were reduced in isolated muscles, but not in adipocytes. These results provide genetic evidence that insulin-induced AS160-Thr649 phosphorylation and/or its binding to 14-3-3 play an important role in regulating whole-body glucose homeostasis, at least in part through regulating GLUT4 trafficking in muscle.
authors.affiliation: MRC Protein Phosphorylation Unit, College of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland, UK. s.chen@dundee.ac.uk
authors.forename: Shuai
authors.initials: S
authors.lastname: Chen
authors.forename: David H
authors.initials: DH
authors.lastname: Wasserman
authors.forename: Carol
authors.initials: C
authors.lastname: MacKintosh
authors.forename: Kei
authors.initials: K
authors.lastname: Sakamoto
mesh_terms: D048948:14-3-3 Proteins / Q000378:metabolism; D017667:Adipocytes / Q000378:metabolism; D000818:Animals; D001692:Biological Transport; D001786:Blood Glucose / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D005260:Female; D020690:GTPase-Activating Proteins / Q000235:genetics* / Q000378:metabolism; D055879:Gene Knock-In Techniques; D005947:Glucose / Q000008:administration & dosage / Q000493:pharmacokinetics; D005951:Glucose Tolerance Test; D051275:Glucose Transporter Type 4 / Q000378:metabolism*; D066298:In Vitro Techniques; D007328:Insulin / Q000097:blood / Q000378:metabolism / Q000494:pharmacology*; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D018482:Muscle, Skeletal / Q000378:metabolism; D009154:Mutation; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding; D021381:Protein Transport
chemical_list: D048948:14-3-3 Proteins; D001786:Blood Glucose; D020690:GTPase-Activating Proteins; D051275:Glucose Transporter Type 4; D007328:Insulin; C495693:Slc2a4 protein, mouse; C505647:Tbc1d4 protein, mouse; D005947:Glucose