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Antibody inhibition of synaptosomal protein of 25 kDa (SNAP-25) and syntaxin 1 reduces rapid exocytosis in insulin-secreting cells.

Vikman, Jenny LU ; Ma, Xiaosong LU ; Hockerman, Gregory H ; Rorsman, Patrik LU and Eliasson, Lena LU orcid (2006) In Journal of Molecular Endocrinology 36(3). p.503-515
Abstract
SNARE-proteins (soluble NSF-attachment protein receptor) are important for Ca2+-dependent exocytosis. We have used capacitance measurements and confocal imaging to dissect the role of synaptosomal protein of 25 kDa (SNAP-25) and syntaxin 1 in rapid exocytosis in insulin-secreting pancreatic ß-cells. Following immunoneutralization of syntaxin 1 and SNAP-25, exocytosis was strongly reduced and associated with a marked reduction in the size of the readily releasable pool (RRP) by 65% and 86% in the presence of the anti-SNAP-25 and anti-syntaxin 1 antibodies respectively. The size of the immediately releasable pool (IRP), a subset of RRP in close association with the voltage-dependent Ca2+-channels, was reduced to an equal extent. The... (More)
SNARE-proteins (soluble NSF-attachment protein receptor) are important for Ca2+-dependent exocytosis. We have used capacitance measurements and confocal imaging to dissect the role of synaptosomal protein of 25 kDa (SNAP-25) and syntaxin 1 in rapid exocytosis in insulin-secreting pancreatic ß-cells. Following immunoneutralization of syntaxin 1 and SNAP-25, exocytosis was strongly reduced and associated with a marked reduction in the size of the readily releasable pool (RRP) by 65% and 86% in the presence of the anti-SNAP-25 and anti-syntaxin 1 antibodies respectively. The size of the immediately releasable pool (IRP), a subset of RRP in close association with the voltage-dependent Ca2+-channels, was reduced to an equal extent. The reduction in IRP correlated with slowed release kinetics and the time constant ({tau}) increased from a control value of 16 to 36 ms and 51 ms after inclusion of anti-SNAP-25 and anti-syntaxin 1 antibodies respectively in the pipette solution. We further show that SNAP-25 and syntaxin 1 aggregate in clusters along the plasma membrane. The size of these clusters was estimated to be ~300 nm and every ß-cell contained ~400 SNAP-25/syntaxin 1 clusters. Whereas the inhibitory action of the anti-syntaxin 1 antibody on exocytosis could be attributed almost entirely to suppression of the voltage-dependent Ca2+-current (–40%), the effect of the anti-SNAP-25 antibody was not mediated by decreased Ca2+-entry and is more likely due to a direct interference with the exocytotic machinery. Our data are consistent with the concept that both syntaxin 1 and SNAP-25 are required for rapid exocytosis in ß-cells. (Less)
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author
; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Molecular Endocrinology
volume
36
issue
3
pages
503 - 515
publisher
Society for Endocrinology
external identifiers
  • wos:000238316400009
  • scopus:33745182916
ISSN
1479-6813
DOI
10.1677/jme.1.01978
language
English
LU publication?
yes
id
cc9381e6-31f0-4591-bc09-2acb7829c1f1 (old id 156586)
date added to LUP
2016-04-01 16:59:51
date last changed
2021-10-06 02:29:32
@article{cc9381e6-31f0-4591-bc09-2acb7829c1f1,
  abstract     = {SNARE-proteins (soluble NSF-attachment protein receptor) are important for Ca2+-dependent exocytosis. We have used capacitance measurements and confocal imaging to dissect the role of synaptosomal protein of 25 kDa (SNAP-25) and syntaxin 1 in rapid exocytosis in insulin-secreting pancreatic ß-cells. Following immunoneutralization of syntaxin 1 and SNAP-25, exocytosis was strongly reduced and associated with a marked reduction in the size of the readily releasable pool (RRP) by 65% and 86% in the presence of the anti-SNAP-25 and anti-syntaxin 1 antibodies respectively. The size of the immediately releasable pool (IRP), a subset of RRP in close association with the voltage-dependent Ca2+-channels, was reduced to an equal extent. The reduction in IRP correlated with slowed release kinetics and the time constant ({tau}) increased from a control value of 16 to 36 ms and 51 ms after inclusion of anti-SNAP-25 and anti-syntaxin 1 antibodies respectively in the pipette solution. We further show that SNAP-25 and syntaxin 1 aggregate in clusters along the plasma membrane. The size of these clusters was estimated to be ~300 nm and every ß-cell contained ~400 SNAP-25/syntaxin 1 clusters. Whereas the inhibitory action of the anti-syntaxin 1 antibody on exocytosis could be attributed almost entirely to suppression of the voltage-dependent Ca2+-current (–40%), the effect of the anti-SNAP-25 antibody was not mediated by decreased Ca2+-entry and is more likely due to a direct interference with the exocytotic machinery. Our data are consistent with the concept that both syntaxin 1 and SNAP-25 are required for rapid exocytosis in ß-cells.},
  author       = {Vikman, Jenny and Ma, Xiaosong and Hockerman, Gregory H and Rorsman, Patrik and Eliasson, Lena},
  issn         = {1479-6813},
  language     = {eng},
  number       = {3},
  pages        = {503--515},
  publisher    = {Society for Endocrinology},
  series       = {Journal of Molecular Endocrinology},
  title        = {Antibody inhibition of synaptosomal protein of 25 kDa (SNAP-25) and syntaxin 1 reduces rapid exocytosis in insulin-secreting cells.},
  url          = {http://dx.doi.org/10.1677/jme.1.01978},
  doi          = {10.1677/jme.1.01978},
  volume       = {36},
  year         = {2006},
}