Functional consequence of targeting protein kinase B/Akt to GLUT4 vesicles.
We have investigated the role of protein kinase B (Akt) in the insulin-stimulated translocation of vesicles containing the insulin-responsive isoform of glucose transporter (GLUT4) to the plasma membrane of adipocytes. Previous reports have suggested that protein kinase B can bind to intracellular GLUT4 vesicles in an insulin-dependent manner, but the functional consequence of this translocation is not known. In this study we have artificially targeted constitutively active and kinase-inactive mutants of protein kinase B to intracellular GLUT4 vesicles by fusing them with the N-terminus of GLUT4 itself. We examined the effect of these mutants on the insulin-dependent translocation of the insulin-responsive amino peptidase IRAP (a bona fide GLUT4-vesicle-resident protein). A kinase-inactive protein kinase B targeted to GLUT4 vesicles was an extremely effective dominant-negative inhibitor of insulin-stimulated IRAP translocation to the plasma membrane. By contrast, a kinase-inactive protein kinase B expressed in the cytoplasm did not have an effect. The results suggest that protein kinase B has an important functional role at, or in the vicinity of, GLUT4 vesicles in the insulin-dependent translocation of those vesicles to the plasma membrane of adipocytes.
Ducluzeau
Pierre-Henri
PH
Department of Biochemistry, School of Medical Sciences, University of Bristol, UK.
Fletcher
Laura M
LM
Welsh
Gavin I
GI
Tavaré
Jeremy M
JM
D016475:3T3 Cells; D017667:Adipocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D000626:Aminopeptidases / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D000818:Animals; D015415:Biomarkers; D002451:Cell Compartmentation / Q000187:drug effects / Q000235:genetics; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D010122:Cystinyl Aminopeptidase; D004268:DNA-Binding Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D051275:Glucose Transporter Type 4; D007328:Insulin / Q000378:metabolism* / Q000494:pharmacology; D051379:Mice; D009004:Monosaccharide Transport Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D009124:Muscle Proteins; D009154:Mutation / Q000187:drug effects / Q000235:genetics; D017346:Protein Serine-Threonine Kinases; D017434:Protein Structure, Tertiary / Q000187:drug effects / Q000502:physiology; D021381:Protein Transport / Q000187:drug effects / Q000502:physiology*; D011518:Proto-Oncogene Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D011993:Recombinant Fusion Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D022161:Transport Vesicles / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure
D015415:Biomarkers; D004268:DNA-Binding Proteins; D051275:Glucose Transporter Type 4; D007328:Insulin; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; D011518:Proto-Oncogene Proteins; D011993:Recombinant Fusion Proteins; C495693:Slc2a4 protein, mouse; D014157:Transcription Factors; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D000626:Aminopeptidases; D010122:Cystinyl Aminopeptidase; C105964:leucyl-cystinyl aminopeptidase; D005947:Glucose