QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online 29 November 2005
doi: 10.1242/jcs.02684

This Article Figures Only Full Text Full Text (PDF) Supplementary Material All Versions of this Article: jcs.02684v1 118/24/5873    most recent 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 Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Hao, M. Articles by Piston, D. W. Search for Related Content PubMed PubMed Citation Articles by Hao, M. Articles by Piston, D. W.

Regulation of two insulin granule populations within the reserve pool by distinct calcium sources

¹ Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN 37232, USA
² Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, TN 37232, USA

^* Author for correspondence (e-mail: dave.piston{at}vanderbilt.edu)

Accepted 9 September 2005

Insulin granule trafficking is a key step of glucose-stimulated insulin secretion from pancreatic ß cells. Using quantitative live cell imaging, we examined insulin granule movements within the reserve pool upon secretory stimulation in ßTC3 cells. For this study, we developed a custom image analysis program that permitted automatic tracking of the individual motions of over 20,000 granules. This analysis of a large sample size enabled us to study micro-populations of granules that were not quantifiable in previous studies. While over 90% of the granules depend on Ca²⁺ efflux from the endoplasmic reticulum for their mobilization, a small and fast-moving population of granules responds to extracellular Ca²⁺ influx after depolarization of the plasma membrane. We show that this differential regulation of the two granule populations is consistent with localized Ca²⁺ signals, and that the cytoskeletal network is involved in both types of granule movement. The fast-moving granules are correlated temporally and spatially to the replacement of the secreted insulin granules, which supports the hypothesis that these granules are responsible for replenishing the readily releasable pool. Our study provides a model by which glucose and other secretory stimuli can regulate the readily releasable pool through the same mechanisms that regulate insulin secretion.

Key words: Insulin, Granules, Calcium, Reserve pool, Pancreatic beta cells

This article has been cited by other articles:

				M. Hao, W. S. Head, S. C. Gunawardana, A. H. Hasty, and D. W. Piston Direct Effect of Cholesterol on Insulin Secretion: A Novel Mechanism for Pancreatic {beta}-Cell Dysfunction Diabetes, September 1, 2007; 56(9): 2328 - 2338. [Abstract] [Full Text] [PDF]

				M. M. Tamkun, K. M. S. O'Connell, and A. S. Rolig A cytoskeletal-based perimeter fence selectively corrals a sub-population of cell surface Kv2.1 channels J. Cell Sci., July 15, 2007; 120(14): 2413 - 2423. [Abstract] [Full Text] [PDF]