Focal adhesion remodeling is crucial for glucose-stimulated insulin secretion and involves activation of focal adhesion kinase and paxillin.
Author(s)
Rondas, D
Tomas, A
Halban, PA
Type
Journal Article
Abstract
OBJECTIVE: Actin cytoskeleton remodeling is known to be involved in glucose-stimulated insulin secretion (GSIS). We have observed glucose-stimulated changes at the β-cell basal membrane similar to focal adhesion remodeling in cell migration. This led us to study the role of two key focal adhesion proteins, focal adhesion kinase (FAK) and paxillin, in GSIS. RESEARCH DESIGN AND METHODS: All studies were performed using rat primary β-cells or isolated islets. Protein phosphorylation and subcellular localization were determined by Western blotting and confocal immunofluorescence, respectively. Insulin was measured by radioimmunoassay. Both siRNA and pharmacological approaches were used to assess the role of FAK and paxillin in glucose-stimulated focal adhesion remodeling and insulin secretion. RESULTS: Glucose stimulation of β-cells in monolayer significantly increased phosphorylation of FAK and paxillin as well as cell surface area. This coincided with the appearance at the basal membrane of numerous shorter actin filopodial extensions, containing not only phosphorylated paxillin, FAK, and extracellular signal-related kinase 1/2 but also two SNARE proteins, synaptosomal-associated protein 25 and syntaxin 1, indicating involvement in exocytosis. SR7037 completely inhibited this sequence of events, indicating the requirement of increased cytosolic Ca²(+). Furthermore, knockdown of paxillin significantly decreased GSIS, as did inhibition of glucose-induced FAK phosphorylation by compound Y15. Key findings were confirmed in β-cells within the natural setting of islets. CONCLUSIONS: Glucose-stimulated remodeling of focal adhesions and phosphorylation of FAK and paxillin are involved in full development of GSIS, indicating a previously unknown role for focal adhesion remodeling in pancreatic β-cell function.
Date Issued
2011-04-01
Start Page
1146
End Page
1157
Journal / Book Title
Diabetes
Volume
60
Issue
4
Copyright Statement
2011 by the American Diabetes Association. Readers may use this article as
long as the work is properly cited, the use is educational and not for profit, and the work is not altered. See http://creativecommons.org/licenses/by-nc-nd/3.0/ for details
long as the work is properly cited, the use is educational and not for profit, and the work is not altered. See http://creativecommons.org/licenses/by-nc-nd/3.0/ for details
Identifier
http://www.ncbi.nlm.nih.gov/pubmed/21357465
db10-0946
Subjects
Animals
Blotting, Western
Cells, Cultured
Electrophoresis, Polyacrylamide Gel
Flavonoids
Fluorescent Antibody Technique
Focal Adhesion Protein-Tyrosine Kinases
Focal Adhesions
Glucose
In Vitro Techniques
Insulin
Microscopy, Confocal
Mitogen-Activated Protein Kinase 1
Mitogen-Activated Protein Kinase 3
Paxillin
Phosphorylation
RNA Interference
Rats
Endocrinology & Metabolism
11 Medical And Health Sciences
Publication Status
Published
Coverage Spatial
United States