Regulation of Insulin Secretion by Phosphatidylinositol-4,5-Bisphosphate
File(s)
Accepted version
Author(s)
Tomas, A
Yermen, B
Regazzi, R
Pessin, JE
Halban, PA
Type
Journal Article
Abstract
The role of PIP(2) in pancreatic beta cell function was examined here using the beta cell line MIN6B1. Blocking PIP(2) with PH-PLC-GFP or PIP5KIgamma RNAi did not impact on glucose-stimulated secretion although susceptibility to apoptosis was increased. Over-expression of PIP5KIgamma improved cell survival and inhibited secretion with accumulation of endocytic vacuoles containing F-actin, PIP(2), transferrin receptor, caveolin 1, Arf6 and the insulin granule membrane protein phogrin but not insulin. Expression of constitutively active Arf6 Q67L also resulted in vacuole formation and inhibition of secretion, which was reversed by PH-PLC-GFP co-expression. PIP(2) co-localized with gelsolin and F-actin, and gelsolin co-expression partially reversed the secretory defect of PIP5KIgamma-over-expressing cells. RhoA/ROCK inhibition increased actin depolymerization and secretion, which was prevented by over-expressing PIP5KIgamma, while blocking PIP(2) reduced constitutively active RhoA V14-induced F-actin polymerization. In conclusion, although PIP(2) plays a pro-survival role in MIN6B1 cells, excessive PIP(2) production because of PIP5KIgamma over-expression inhibits secretion because of both a defective Arf6/PIP5KIgamma-dependent endocytic recycling of secretory membrane and secretory membrane components such as phogrin and the RhoA/ROCK/PIP5KIgamma-dependent perturbation of F-actin cytoskeleton remodelling.
Date Issued
2009-09-28
Date Acceptance
2009-09-25
Citation
Traffic, 2009, 11 (1), pp.123-137
ISSN
1600-0854
Publisher
Wiley
Start Page
123
End Page
137
Journal / Book Title
Traffic
Volume
11
Issue
1
Copyright Statement
© 2009 John Wiley & Sons A/S
Subjects
Animals
Apoptosis
Blotting, Western
Cell Culture Techniques
Cell Line
Cell Survival
Electrophoresis, Polyacrylamide Gel
Endocytosis
Glucose
In Situ Nick-End Labeling
Insulin
Insulin-Secreting Cells
Mice
Microscopy, Confocal
Microscopy, Fluorescence
Phosphatidylinositol 4,5-Diphosphate
Phosphotransferases (Alcohol Group Acceptor)
Protein Transport
Vacuoles
Developmental Biology
0601 Biochemistry And Cell Biology
Publication Status
Published