title: Cerebellar neurons possess a vesicular compartment structurally and functionally similar to Glut4-storage vesicles from peripheral insulin-sensitive tissues.
abstract: The insulin-sensitive isoform of the glucose transporting protein, Glut4, is expressed in fat as well as in skeletal and cardiac muscle and is responsible for the effect of insulin on blood glucose clearance. Recent studies have revealed that Glut4 is also expressed in the brain, although the intracellular compartmentalization and regulation of Glut4 in neurons remains unknown. Using sucrose gradient centrifugation, immunoadsorption and immunofluorescence staining, we have shown that Glut4 in the cerebellum is localized in intracellular vesicles that have the sedimentation coefficient, the buoyant density, and the protein composition similar to the insulin-responsive Glut4-storage vesicles from fat and skeletal muscle cells. In cultured cerebellar neurons, insulin stimulates glucose uptake and causes translocation of Glut4 to the cell surface. Using 18FDG (18fluoro-2-deoxyglucose) positron emission tomography, we found that physical exercise acutely increases glucose uptake in the cerebellum in vivo. Prolonged physical exercise increases expression of the Glut4 protein in the cerebellum. Our results suggest that neurons have a novel type of translocation-competent vesicular compartment which is regulated by insulin and physical exercise similar to Glut4-storage vesicles in peripheral insulin target tissues.
authors.affiliation: Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118, USA.
authors.forename: Kyriaki
authors.initials: K
authors.lastname: Bakirtzi
authors.forename: Gabriel
authors.initials: G
authors.lastname: Belfort
authors.forename: Ignacio
authors.initials: I
authors.lastname: Lopez-Coviella
authors.forename: Darshini
authors.initials: D
authors.lastname: Kuruppu
authors.forename: Lei
authors.initials: L
authors.lastname: Cao
authors.forename: E Dale
authors.initials: ED
authors.lastname: Abel
authors.forename: Anna-Liisa
authors.initials: AL
authors.lastname: Brownell
authors.forename: Konstantin V
authors.initials: KV
authors.lastname: Kandror
mesh_terms: D000273:Adipose Tissue / Q000737:chemistry / Q000166:cytology / Q000378:metabolism; D000818:Animals; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D051275:Glucose Transporter Type 4 / Q000502:physiology*; D007328:Insulin / Q000502:physiology*; D051379:Mice; D018482:Muscle, Skeletal / Q000166:cytology / Q000378:metabolism / Q000502:physiology; D009474:Neurons / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D021381:Protein Transport / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013572:Synaptic Vesicles / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*
chemical_list: D051275:Glucose Transporter Type 4; D007328:Insulin; C495693:Slc2a4 protein, mouse