VAMP-2 and cellubrevin are expressed in pancreatic beta-cells and are essential for Ca(2+)-but not for GTP gamma S-induced insulin secretion.
EMBO J
; 14(12): 2723-30, 1995 Jun 15.
Article
en En
| MEDLINE
| ID: mdl-7796801
VAMP proteins are important components of the machinery controlling docking and/or fusion of secretory vesicles with their target membrane. We investigated the expression of VAMP proteins in pancreatic beta-cells and their implication in the exocytosis of insulin. cDNA cloning revealed that VAMP-2 and cellubrevin, but not VAMP-1, are expressed in rat pancreatic islets and that their sequence is identical to that isolated from rat brain. Pancreatic beta-cells contain secretory granules that store and secrete insulin as well as synaptic-like microvesicles carrying gamma-aminobutyric acid. After subcellular fractionation on continuous sucrose gradients, VAMP-2 and cellubrevin were found to be associated with both types of secretory vesicle. The association of VAMP-2 with insulin-containing granules was confirmed by confocal microscopy of primary cultures of rat pancreatic beta-cells. Pretreatment of streptolysin-O permeabilized insulin-secreting cells with tetanus and botulinum B neurotoxins selectively cleaved VAMP-2 and cellubrevin and abolished Ca(2+)-induced insulin release (IC50 approximately 15 nM). By contrast, the pretreatment with tetanus and botulinum B neurotoxins did not prevent GTP gamma S-stimulated insulin secretion. Taken together, our results show that pancreatic beta-cells express VAMP-2 and cellubrevin and that one or both of these proteins selectively control Ca(2+)-mediated insulin secretion.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Calcio
/
Islotes Pancreáticos
/
Insulina
/
Proteínas de la Membrana
/
Proteínas del Tejido Nervioso
Límite:
Animals
Idioma:
En
Revista:
EMBO J
Año:
1995
Tipo del documento:
Article
País de afiliación:
Suiza
Pais de publicación:
Reino Unido