The stimulatory action of tolbutamide on Ca2+-dependent exocytosis in pancreatic beta cells is mediated by a 65-kDa mdr-like P-glycoprotein
Barg, Sebastian LU ; Renström, Erik LU ; Berggren, P O ; Bertorello, A ; Bokvist, K ; Braun, M ; Eliasson, Lena LU
; Holmes, W E
; Kohler, M
and Rorsman, Patrik
LU
, et al.
(1999)
In Proceedings of the National Academy of Sciences
96(10).
p.5539-5544
- Abstract
- Intracellular application of the sulfonylurea tolbutamide during whole-cell patch-clamp recordings stimulated exocytosis >5-fold when applied at a cytoplasmic Ca2+ concentration of 0.17 microM. This effect was not detectable in the complete absence of cytoplasmic Ca2+ and when exocytosis was elicited by guanosine 5'-O-(3-thiotriphosphate) (GTPgammaS). The stimulatory action could be antagonized by the sulfonamide diazoxide, by the Cl--channel blocker 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS), by intracellular application of the antibody JSB1 [originally raised against a 170-kDa multidrug resistance (mdr) protein], and by tamoxifen (an inhibitor of the mdr- and volume-regulated Cl- channels). Immunocytochemistry and... (More)
- Intracellular application of the sulfonylurea tolbutamide during whole-cell patch-clamp recordings stimulated exocytosis >5-fold when applied at a cytoplasmic Ca2+ concentration of 0.17 microM. This effect was not detectable in the complete absence of cytoplasmic Ca2+ and when exocytosis was elicited by guanosine 5'-O-(3-thiotriphosphate) (GTPgammaS). The stimulatory action could be antagonized by the sulfonamide diazoxide, by the Cl--channel blocker 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS), by intracellular application of the antibody JSB1 [originally raised against a 170-kDa multidrug resistance (mdr) protein], and by tamoxifen (an inhibitor of the mdr- and volume-regulated Cl- channels). Immunocytochemistry and Western blot analyses revealed that JSB1 recognizes a 65-kDa protein in the secretory granules. This protein exhibited no detectable binding of sulfonylureas and is distinct from the 140-kDa sulfonylurea high-affinity sulfonylurea receptors also present in the granules. We conclude that (i) tolbutamide stimulates Ca2+-dependent exocytosis secondary to its binding to a 140-kDa high-affinity sulfonylurea receptor in the secretory granules; and (ii) a granular 65-kDa mdr-like protein mediates the action. The processes thus initiated culminate in the activation of a granular Cl- conductance. We speculate that the activation of granular Cl- fluxes promotes exocytosis (possibly by providing the energy required for membrane fusion) by inducing water uptake and an increased intragranular hydrostatic pressure. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/1114680
- author
- Barg, Sebastian
LU
; Renström, Erik
LU
; Berggren, P O
; Bertorello, A
; Bokvist, K
; Braun, M
; Eliasson, Lena
LU
; Holmes, W E
; Kohler, M
and Rorsman, Patrik
LU
, et al. (More)
- Barg, Sebastian
LU
; Renström, Erik
LU
; Berggren, P O
; Bertorello, A
; Bokvist, K
; Braun, M
; Eliasson, Lena
LU
; Holmes, W E
; Kohler, M
; Rorsman, Patrik
LU
and Thevenod, F
(Less)
- organization
- publishing date
- 1999
- type
- Contribution to journal
- publication status
- published
- subject
- in
- Proceedings of the National Academy of Sciences
- volume
- 96
- issue
- 10
- pages
- 5539 - 5544
- publisher
- National Academy of Sciences
- external identifiers
-
- pmid:10318919
- ISSN
- 1091-6490
- language
- English
- LU publication?
- yes
- id
- d26fa69a-a280-4c3d-a301-e479248b8227 (old id 1114680)
- alternative location
- http://www.pnas.org/content/96/10/5539.full
- date added to LUP
- 2016-04-01 11:32:58
- date last changed
- 2019-03-08 02:45:38
@article{d26fa69a-a280-4c3d-a301-e479248b8227,
abstract = {{Intracellular application of the sulfonylurea tolbutamide during whole-cell patch-clamp recordings stimulated exocytosis >5-fold when applied at a cytoplasmic Ca2+ concentration of 0.17 microM. This effect was not detectable in the complete absence of cytoplasmic Ca2+ and when exocytosis was elicited by guanosine 5'-O-(3-thiotriphosphate) (GTPgammaS). The stimulatory action could be antagonized by the sulfonamide diazoxide, by the Cl--channel blocker 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS), by intracellular application of the antibody JSB1 [originally raised against a 170-kDa multidrug resistance (mdr) protein], and by tamoxifen (an inhibitor of the mdr- and volume-regulated Cl- channels). Immunocytochemistry and Western blot analyses revealed that JSB1 recognizes a 65-kDa protein in the secretory granules. This protein exhibited no detectable binding of sulfonylureas and is distinct from the 140-kDa sulfonylurea high-affinity sulfonylurea receptors also present in the granules. We conclude that (i) tolbutamide stimulates Ca2+-dependent exocytosis secondary to its binding to a 140-kDa high-affinity sulfonylurea receptor in the secretory granules; and (ii) a granular 65-kDa mdr-like protein mediates the action. The processes thus initiated culminate in the activation of a granular Cl- conductance. We speculate that the activation of granular Cl- fluxes promotes exocytosis (possibly by providing the energy required for membrane fusion) by inducing water uptake and an increased intragranular hydrostatic pressure.}},
author = {{Barg, Sebastian and Renström, Erik and Berggren, P O and Bertorello, A and Bokvist, K and Braun, M and Eliasson, Lena and Holmes, W E and Kohler, M and Rorsman, Patrik and Thevenod, F}},
issn = {{1091-6490}},
language = {{eng}},
number = {{10}},
pages = {{5539--5544}},
publisher = {{National Academy of Sciences}},
series = {{Proceedings of the National Academy of Sciences}},
title = {{The stimulatory action of tolbutamide on Ca2+-dependent exocytosis in pancreatic beta cells is mediated by a 65-kDa mdr-like P-glycoprotein}},
url = {{http://www.pnas.org/content/96/10/5539.full}},
volume = {{96}},
year = {{1999}},
}