Subcellular distribution and function of Rab3A, B, C, and D isoforms in insulin-secreting cells

Details

Serval ID
serval:BIB_DB4A9DF5CE28
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Subcellular distribution and function of Rab3A, B, C, and D isoforms in insulin-secreting cells
Journal
Molecular Endocrinology
Author(s)
Iezzi  M., Escher  G., Meda  P., Charollais  A., Baldini  G., Darchen  F., Wollheim  C. B., Regazzi  R.
ISSN
0888-8809 (Print)
Publication state
Published
Issued date
02/1999
Volume
13
Number
2
Pages
202-12
Notes
Journal Article
Research Support, Non-U.S. Gov't --- Old month value: Feb
Abstract
Insulin-secreting cells express four GTPases of the Rab3 family. After separation of extracts of INS-1 cells on a sucrose density gradient, the bulk of the A, B, and C isoforms was recovered in the fractions enriched in insulin-containing secretory granules. Rab3D was also mainly associated with secretory granules, but a fraction of this isoform was localized on lighter organelles. Analyses by confocal microscopy of immunostained HIT-T15 cells transfected with epitope-tagged constructs confirmed the distribution of the Rab3 isoforms. Transfection of HIT-T15 cells with GTPase-deficient mutants of the Rab3 isoforms decreased nutrient-induced insulin release to different degrees (D>B>A>>C), while overexpression of Rab3 wild types had minor or no effects. Expression of the same Rab3 mutants in PC12 cells provoked an inhibition of K+-stimulated secretion of dense core vesicles, indicating that, in beta-cells and neuroendocrine cells, the four Rab3 isoforms play a similar role in exocytosis. A Rab3A/C chimera in which the carboxyterminal domain of A was replaced with the corresponding region of C inhibited insulin secretion as Rab3A. In contrast, a Rab3C/A chimera containing the amino-terminal domain of C was less potent and reduced exocytosis as Rab3C. This suggests that the degree of inhibition obtained after transfection of the Rab3 isoforms is determined by differences in the variable amino-terminal region.
Keywords
Animals Blotting, Western Cells, Cultured Centrifugation, Density Gradient Cytoplasmic Granules/secretion Densitometry Enzyme-Linked Immunosorbent Assay Exocytosis GTP-Binding Proteins/*metabolism Humans Image Processing, Computer-Assisted Insulin/*secretion Islets of Langerhans/cytology/*secretion Microscopy, Fluorescence Mutagenesis, Site-Directed PC12 Cells Rats Recombinant Fusion Proteins/metabolism Transfection rab3 GTP-Binding Proteins
Pubmed
Web of science
Open Access
Yes
Create date
24/01/2008 14:30
Last modification date
20/08/2019 16:00
Usage data