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

First published online 20 February 2007
doi: 10.1242/jcs.03406

This Article Figures Only Full Text Full Text (PDF) Supplementary Material All Versions of this Article: jcs.03406v1 120/6/973    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 Handley, M. T. W. Articles by Burgoyne, R. D. Search for Related Content PubMed PubMed Citation Articles by Handley, M. T. W. Articles by Burgoyne, R. D. Social Bookmarking                         What's this?

Differential dynamics of Rab3A and Rab27A on secretory granules

The Physiological Laboratory, School of Biomedical Sciences, University of Liverpool, Crown Street, Liverpool, L69 3BX, UK

^* Author for correspondence (e-mail: burgoyne{at}liv.ac.uk)

Accepted 12 January 2007

We have assessed the dynamics of the association of Rab3A and Rab27A with secretory granules at various stages of their life in PC12 cells. Endogenous Rab3A colocalised with the secretory granule marker secretogranin II (SGII) and expressed EGFP-Rab3A and ECFP-Rab27A colocalised with one another. The extent of colocalisation between EGFP-Rab3A or EGFP-Rab27 and SGII increased after longer times post transfection suggesting that these Rab proteins are preferentially recruited to newly synthesised granules. Following the release of immature secretory granules from the trans-Golgi network, Rab3A and Rab27A became associated with the immature granules after a lag period of around 20 minutes. Rab dynamics on granules were analysed in fluorescence recovery after photobleaching (FRAP) experiments. The recovery profile of EGFP-Rab27A was comparable to that of ppANF-EGFP, whereas the recovery profile of EGFP-Rab3A was significantly faster, indicating that Rab3A but not Rab27A might be rapidly exchanged between granules and cytosol. Inhibition of heat-shock protein 90 with 10 µM geldanamycin did not affect the exchange process or regulated exocytosis. Rab dynamics during stimulation with 300 µM ATP were analysed in live cells. Loss of granular ppANF-EGFP fluorescence was seen at the cell periphery after stimulation but only limited changes in EGFP-Rab3A and EGFP-Rab27A fluorescence was observed, indicating that the Rab proteins do not immediately dissociate or disperse on stimulation. The data suggest potentially distinct roles for Rab3A and Rab27A and we suggest that the finding that young secretory granules have a higher capacity for binding Rab3A and Rab27A is functionally important for preferential exocytosis from these granules.

Key words: Rab proteins, GTPases, Exocytosis, Secretion, Secretory vesicle

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

This article has been cited by other articles:

				S. L. Edwards, N. K. Charlie, J. E. Richmond, J. Hegermann, S. Eimer, and K. G. Miller Impaired dense core vesicle maturation in Caenorhabditis elegans mutants lacking Rab2 J. Cell Biol., September 21, 2009; 186(6): 881 - 895. [Abstract] [Full Text] [PDF]

				M. T. Branham, M. A. Bustos, G. A. De Blas, H. Rehmann, V. E. P. Zarelli, C. L. Trevino, A. Darszon, L. S. Mayorga, and C. N. Tomes Epac Activates the Small G Proteins Rap1 and Rab3A to Achieve Exocytosis J. Biol. Chem., September 11, 2009; 284(37): 24825 - 24839. [Abstract] [Full Text] [PDF]

				T. D. Nightingale, K. Pattni, A. N. Hume, M. C. Seabra, and D. F. Cutler Rab27a and MyRIP regulate the amount and multimeric state of VWF released from endothelial cells Blood, May 14, 2009; 113(20): 5010 - 5018. [Abstract] [Full Text] [PDF]

				J. J. Park and Y. P. Loh Minireview: How Peptide Hormone Vesicles Are Transported to the Secretion Site for Exocytosis Mol. Endocrinol., December 1, 2008; 22(12): 2583 - 2595. [Abstract] [Full Text] [PDF]