Gelsolin associates with the N terminus of syntaxin 4 to regulate insulin granule exocytosis

Michael A. Kalwat, Dean A. Wiseman, Wei Luo, Zhanxiang Wang, Debbie C. Thurmond

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

The plasma membrane soluble N-ethylmaleimide-sensitive factor attachment receptor (SNARE) protein syntaxin (Syn)4 is required for biphasic insulin secretion, although how it regulates each phase remains unclear. In a screen to identify new Syn4-interacting factors, the calcium-activated F-actin-severing protein gelsolin was revealed. Gelsolin has been previously implicated as a positive effector of insulin secretion, although a molecular mechanism to underlie this function is lacking. Toward this, our in vitro binding studies showed the Syn4-gelsolin interaction to be direct and mediated by the N-terminal Ha domain (amino acid residues 39-70) of Syn4. Syn4-gelsolin complexes formed under basal conditions and dissociated upon acute glucose or KCl stimulation; nifedipine blocked dissociation. The dissociating action of secretagogues could be mimicked by expression of the N-terminal Ha domain of Syn4 fused to green fluorescent protein (GFP) (GFP-39-70). Furthermore, GFP-39-70 expression in isolated mouse islet and clonal MIN6 β-cells initiated insulin release in the absence of appropriate stimuli. Consistent with this, the inhibitory GFP-39-70 peptide also initiated Syn4 activation in the absence of stimuli. Moreover, although MIN6 β-cells expressing the GFP-39-70 peptide maintained normal calcium influx in response to KCl, KCl-stimulated insulin secretion and the triggering pathway of insulin secretion were significantly impaired. Taken together, these data support a mechanistic model for gelsolin's role in insulin exocytosis: gelsolin clamps unsolicited soluble N-ethylmaleimide-sensitive factor attachment receptor (SNARE)-regulated exocytosis through direct association with Syn4 in the absence of appropriate stimuli, which is relieved upon stimulus-induced calcium influx to activate gelsolin and induce its dissociation from Syn4 to facilitate insulin exocytosis.

Original languageEnglish
Pages (from-to)128-141
Number of pages14
JournalMolecular Endocrinology
Volume26
Issue number1
DOIs
StatePublished - Jan 2012

Fingerprint

Gelsolin
Qa-SNARE Proteins
Exocytosis
Green Fluorescent Proteins
Insulin
N-Ethylmaleimide-Sensitive Proteins
Calcium
Biphasic Insulins
Peptides
Secretory Pathway
Nifedipine
Actins
Membrane Proteins
Cell Membrane
Amino Acids
Glucose

ASJC Scopus subject areas

  • Molecular Biology
  • Endocrinology

Cite this

Gelsolin associates with the N terminus of syntaxin 4 to regulate insulin granule exocytosis. / Kalwat, Michael A.; Wiseman, Dean A.; Luo, Wei; Wang, Zhanxiang; Thurmond, Debbie C.

In: Molecular Endocrinology, Vol. 26, No. 1, 01.2012, p. 128-141.

Research output: Contribution to journalArticle

Kalwat, Michael A. ; Wiseman, Dean A. ; Luo, Wei ; Wang, Zhanxiang ; Thurmond, Debbie C. / Gelsolin associates with the N terminus of syntaxin 4 to regulate insulin granule exocytosis. In: Molecular Endocrinology. 2012 ; Vol. 26, No. 1. pp. 128-141.
@article{10ef41f07da14f68a85706d53f502774,
title = "Gelsolin associates with the N terminus of syntaxin 4 to regulate insulin granule exocytosis",
abstract = "The plasma membrane soluble N-ethylmaleimide-sensitive factor attachment receptor (SNARE) protein syntaxin (Syn)4 is required for biphasic insulin secretion, although how it regulates each phase remains unclear. In a screen to identify new Syn4-interacting factors, the calcium-activated F-actin-severing protein gelsolin was revealed. Gelsolin has been previously implicated as a positive effector of insulin secretion, although a molecular mechanism to underlie this function is lacking. Toward this, our in vitro binding studies showed the Syn4-gelsolin interaction to be direct and mediated by the N-terminal Ha domain (amino acid residues 39-70) of Syn4. Syn4-gelsolin complexes formed under basal conditions and dissociated upon acute glucose or KCl stimulation; nifedipine blocked dissociation. The dissociating action of secretagogues could be mimicked by expression of the N-terminal Ha domain of Syn4 fused to green fluorescent protein (GFP) (GFP-39-70). Furthermore, GFP-39-70 expression in isolated mouse islet and clonal MIN6 β-cells initiated insulin release in the absence of appropriate stimuli. Consistent with this, the inhibitory GFP-39-70 peptide also initiated Syn4 activation in the absence of stimuli. Moreover, although MIN6 β-cells expressing the GFP-39-70 peptide maintained normal calcium influx in response to KCl, KCl-stimulated insulin secretion and the triggering pathway of insulin secretion were significantly impaired. Taken together, these data support a mechanistic model for gelsolin's role in insulin exocytosis: gelsolin clamps unsolicited soluble N-ethylmaleimide-sensitive factor attachment receptor (SNARE)-regulated exocytosis through direct association with Syn4 in the absence of appropriate stimuli, which is relieved upon stimulus-induced calcium influx to activate gelsolin and induce its dissociation from Syn4 to facilitate insulin exocytosis.",
author = "Kalwat, {Michael A.} and Wiseman, {Dean A.} and Wei Luo and Zhanxiang Wang and Thurmond, {Debbie C.}",
year = "2012",
month = "1",
doi = "10.1210/me.2011-1112",
language = "English",
volume = "26",
pages = "128--141",
journal = "Molecular Endocrinology",
issn = "0888-8809",
publisher = "The Endocrine Society",
number = "1",

}

TY - JOUR

T1 - Gelsolin associates with the N terminus of syntaxin 4 to regulate insulin granule exocytosis

AU - Kalwat, Michael A.

AU - Wiseman, Dean A.

AU - Luo, Wei

AU - Wang, Zhanxiang

AU - Thurmond, Debbie C.

PY - 2012/1

Y1 - 2012/1

N2 - The plasma membrane soluble N-ethylmaleimide-sensitive factor attachment receptor (SNARE) protein syntaxin (Syn)4 is required for biphasic insulin secretion, although how it regulates each phase remains unclear. In a screen to identify new Syn4-interacting factors, the calcium-activated F-actin-severing protein gelsolin was revealed. Gelsolin has been previously implicated as a positive effector of insulin secretion, although a molecular mechanism to underlie this function is lacking. Toward this, our in vitro binding studies showed the Syn4-gelsolin interaction to be direct and mediated by the N-terminal Ha domain (amino acid residues 39-70) of Syn4. Syn4-gelsolin complexes formed under basal conditions and dissociated upon acute glucose or KCl stimulation; nifedipine blocked dissociation. The dissociating action of secretagogues could be mimicked by expression of the N-terminal Ha domain of Syn4 fused to green fluorescent protein (GFP) (GFP-39-70). Furthermore, GFP-39-70 expression in isolated mouse islet and clonal MIN6 β-cells initiated insulin release in the absence of appropriate stimuli. Consistent with this, the inhibitory GFP-39-70 peptide also initiated Syn4 activation in the absence of stimuli. Moreover, although MIN6 β-cells expressing the GFP-39-70 peptide maintained normal calcium influx in response to KCl, KCl-stimulated insulin secretion and the triggering pathway of insulin secretion were significantly impaired. Taken together, these data support a mechanistic model for gelsolin's role in insulin exocytosis: gelsolin clamps unsolicited soluble N-ethylmaleimide-sensitive factor attachment receptor (SNARE)-regulated exocytosis through direct association with Syn4 in the absence of appropriate stimuli, which is relieved upon stimulus-induced calcium influx to activate gelsolin and induce its dissociation from Syn4 to facilitate insulin exocytosis.

AB - The plasma membrane soluble N-ethylmaleimide-sensitive factor attachment receptor (SNARE) protein syntaxin (Syn)4 is required for biphasic insulin secretion, although how it regulates each phase remains unclear. In a screen to identify new Syn4-interacting factors, the calcium-activated F-actin-severing protein gelsolin was revealed. Gelsolin has been previously implicated as a positive effector of insulin secretion, although a molecular mechanism to underlie this function is lacking. Toward this, our in vitro binding studies showed the Syn4-gelsolin interaction to be direct and mediated by the N-terminal Ha domain (amino acid residues 39-70) of Syn4. Syn4-gelsolin complexes formed under basal conditions and dissociated upon acute glucose or KCl stimulation; nifedipine blocked dissociation. The dissociating action of secretagogues could be mimicked by expression of the N-terminal Ha domain of Syn4 fused to green fluorescent protein (GFP) (GFP-39-70). Furthermore, GFP-39-70 expression in isolated mouse islet and clonal MIN6 β-cells initiated insulin release in the absence of appropriate stimuli. Consistent with this, the inhibitory GFP-39-70 peptide also initiated Syn4 activation in the absence of stimuli. Moreover, although MIN6 β-cells expressing the GFP-39-70 peptide maintained normal calcium influx in response to KCl, KCl-stimulated insulin secretion and the triggering pathway of insulin secretion were significantly impaired. Taken together, these data support a mechanistic model for gelsolin's role in insulin exocytosis: gelsolin clamps unsolicited soluble N-ethylmaleimide-sensitive factor attachment receptor (SNARE)-regulated exocytosis through direct association with Syn4 in the absence of appropriate stimuli, which is relieved upon stimulus-induced calcium influx to activate gelsolin and induce its dissociation from Syn4 to facilitate insulin exocytosis.

UR - http://www.scopus.com/inward/record.url?scp=84855213751&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84855213751&partnerID=8YFLogxK

U2 - 10.1210/me.2011-1112

DO - 10.1210/me.2011-1112

M3 - Article

C2 - 22108804

AN - SCOPUS:84855213751

VL - 26

SP - 128

EP - 141

JO - Molecular Endocrinology

JF - Molecular Endocrinology

SN - 0888-8809

IS - 1

ER -