HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Online-Only Appendix Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Tsuboi, T. Articles by Rutter, G. A. Search for Related Content PubMed PubMed Citation Articles by Tsuboi, T. Articles by Rutter, G. A. Social Bookmarking                What's this?

Sustained Exposure to High Glucose Concentrations Modifies Glucose Signaling and the Mechanics of Secretory Vesicle Fusion in Primary Rat Pancreatic ß-Cells

From the Department of Biochemistry, Henry Wellcome Laboratories for Integrated Cell Signalling, School of Medical Sciences, University Walk, University of Bristol, Bristol, U.K

Address correspondence and reprint requests to Professor Guy A. Rutter, Department of Biochemistry, School of Medical Sciences, University of Bristol, University Walk, Bristol, BS8 1TD, U.K. E-mail: g.a.rutter{at}bristol.ac.uk

Abbreviations: [Ca²⁺]_i, intracellular free Ca²⁺ concentration; EGFP, enhanced GFP; GFP, green fluorescent protein; KRB, Krebs-Ringer buffer; mRFP, monomeric red fluorescent protein; NPY, neuropeptide Y; phogrin, phosphatase on the granule of insulinoma; PPI, preproinsulin; TIRF, total internal reflection fluorescence; Venus, pH-insensitive yellow fluorescent protein

The mechanism(s) by which chronic hyperglycemia impairs glucose-stimulated insulin secretion is poorly defined. Here, we compare the "nanomechanics" of single exocytotic events in primary rat pancreatic ß-cells cultured for 48 h at optimal (10 mmol/l) or elevated (30 mmol/l) glucose concentrations. Cargo release was imaged by total internal reflection fluorescence microscopy of lumen-targeted probes (neuropeptide Y [NPY]-pH–insensitive yellow fluorescent protein [NPY-Venus] or NPY–monomeric red fluorescent protein), while the fate of the vesicle membrane was reported simultaneously with phosphatase-on-the-granule-of-insulinoma–enhanced green fluorescent protein. Under all conditions studied, exocytosis proceeded via a "cavity recapture" mechanism in which the vesicle and plasma membranes fused transiently. While essentially complete release of NPY-Venus was observed in 24 ± 1% of glucose-stimulated exocytotic events in cells maintained at 10 mmol/l glucose, this value was reduced reversibly to 5 ± 2% of events by culture at 30 mmol/l glucose, in line with decreases in Glut2 and glucokinase gene expression, and attenuated glucose-stimulated increases in NADPH and intracellular [Ca²⁺]. Since vesicle release in response to cell depolarization with KCl was not affected by culture at 30 mmol/l glucose, we conclude that hyperglycemia causes the abnormal termination of individual insulin release events principally by inhibiting glucose signaling.

CiteULike    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				C. S. Olofsson, S. Collins, M. Bengtsson, L. Eliasson, A. Salehi, K. Shimomura, A. Tarasov, C. Holm, F. Ashcroft, and P. Rorsman Long-Term Exposure to Glucose and Lipids Inhibits Glucose-Induced Insulin Secretion Downstream of Granule Fusion With Plasma Membrane Diabetes, July 1, 2007; 56(7): 1888 - 1897. [Abstract] [Full Text] [PDF]

				J. Chen, P. B. Jeppesen, I. Nordentoft, and K. Hermansen Stevioside improves pancreatic beta-cell function during glucotoxicity via regulation of acetyl-CoA carboxylase Am J Physiol Endocrinol Metab, June 1, 2007; 292(6): E1906 - E1916. [Abstract] [Full Text] [PDF]

				P. E. MacDonald and P. Rorsman The Ins and Outs of Secretion from Pancreatic {beta}-Cells: Control of Single-Vesicle Exo- and Endocytosis Physiology, April 1, 2007; 22(2): 113 - 121. [Abstract] [Full Text] [PDF]

				L. E. Parton, P. J. McMillen, Y. Shen, E. Docherty, E. Sharpe, F. Diraison, C. P. Briscoe, and G. A. Rutter Limited role for SREBP-1c in defective glucose-induced insulin secretion from Zucker diabetic fatty rat islets: a functional and gene profiling analysis Am J Physiol Endocrinol Metab, November 1, 2006; 291(5): E982 - E994. [Abstract] [Full Text] [PDF]

				G. Harb and G. S Korbutt Effect of prolonged in vitro exposure to high glucose on neonatal porcine pancreatic islets. J. Endocrinol., October 1, 2006; 191(1): 37 - 44. [Abstract] [Full Text] [PDF]

				G. A. Rutter and E. V. Hill Insulin Vesicle Release: Walk, Kiss, Pause ... Then Run Physiology, June 1, 2006; 21(3): 189 - 196. [Abstract] [Full Text] [PDF]