+1 Recommend
0 collections
      • Record: found
      • Abstract: found
      • Article: not found

      Vesicular inhibitory amino acid transporter is present in glucagon-containing secretory granules in alphaTC6 cells, mouse clonal alpha-cells, and alpha-cells of islets of Langerhans.


      pharmacokinetics, metabolism, Amino Acid Transport Systems, Animals, COS Cells, Carrier Proteins, analysis, Clone Cells, Fluorescent Antibody Technique, Glucagon, Islets of Langerhans, chemistry, cytology, Adenosine Triphosphate, Male, Membrane Transport Proteins, Mice, PC12 Cells, Rats, Rats, Wistar, Secretory Vesicles, Vesicular Glutamate Transport Protein 2, Vesicular Inhibitory Amino Acid Transport Proteins, Vesicular Transport Proteins, gamma-Aminobutyric Acid

      Read this article at

          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.


          Islets of Langerhans contain gamma-aminobutyrate (GABA) and may use it as an intercellular transmitter. In beta-cells, GABA is stored in synaptic-like microvesicles and secreted through Ca(2+)-dependent exocytosis. Vesicular inhibitory amino acid transporter (VIAAT), which is responsible for the storage of GABA and glycine in neuronal synaptic vesicles, is believed to be responsible for the storage and secretion of GABA in beta-cells. However, a recent study by Chessler et al. indicated that VIAAT is expressed in the mantle region of islets. In the present study, we investigated the precise localization of VIAAT in rat islets of Langerhans and clonal islet cells and found that it is present in alpha-cells, a minor population of F-cells and alphaTC6 cells, and clonal alpha-cells but not in beta-cells, delta-cells, or MIN6 m9-cells (clonal beta-cells). Combined biochemical, immunohistochemical, and electronmicroscopical evidence indicated that VIAAT is specifically localized with glucagon-containing secretory granules in alpha-cells. ATP-dependent uptake of radiolabeled GABA, which is energetically coupled with a vacuolar proton pump, was detected in digitonin-permeabilized alphaTC6 cells as well as in MIN6 m9 cells. These results demonstrate that functional neuronal VIAAT is present in glucagon-containing secretory granules in alpha-cells and suggest that the ATP-dependent GABA transporter in beta-cells is at least immunologically distinct from VIAAT. Because glucagon-containing secretory granules also contain vesicular glutamate transporter and store L-glutamate, as demonstrated by Hayashi et al., the present results suggest more complex features of the GABAergic phenotype of islets than previously supposed.

          Related collections

          Author and article information



          Comment on this article