Involvement of conventional kinesin in glucose-stimulate secretory granule movements and exocytosis in clonal pancreatic β-cells

Varadi, Aniko; Ainscow, Edward; Allan, Victoria J.; Rutter, Guy A.

Abstract

Recruitment of secretory vesicles to the cell surface is essential for the sustained secretion of insulin in response to glucose. At present, the molecular motors involved in this movement, and the mechanisms whereby they may be regulated, are undefined. To investigate the role of kinesin family members, we labelled densecore vesicles in clonal β-cells using an adenovirally expressed, vesicle-targeted green fluorescent protein (phogrin.EGFP), and employed immunoadsorption to obtain highly purified insulin-containing vesicles. Whereas several kinesin family members were expressed in this cell type, only conventional kinesin heavy chain (KHC) was detected in vesicle preparations. Expression of a dominant-negative KHC motor domain (KHCmut) blocked all vesicular movements with velocity >0.4 μm second-1, which demonstrates that kinesin activity was essential for vesicle motility in live β-cells. Moreover, expression of KHCmut strongly inhibited the sustained, but not acute, stimulation of secretion by glucose. Finally, vesicle movement was stimulated by ATP dose-dependently in permeabilized cells, which suggests that glucose-induced increases in cytosolic [ATP] mediate the effects of the sugar in vivo, by enhancing kinesin activity. These data therefore provide evidence for a novel mechanism whereby glucose may enhance insulin release.

• Journal Article Type: Review
• Publication Date: Nov 1, 2002
• Journal: Journal of Cell Science
• Print ISSN: 0021-9533
• Electronic ISSN: 1477-9137
• Publisher: Company of Biologists
• Peer Reviewed: Peer Reviewed
• Volume: 115
• Issue: 21
• Pages: 4177-4189
• DOI: https://doi.org/10.1242/jcs.00083
• Keywords: kinesin, insulin, exocytosis, glucose, islet, beta cell, pancreas
• Public URL: https://uwe-repository.worktribe.com/output/1075778
• Publisher URL: http://dx.doi.org/10.1242/jcs.00083
• Additional Information: Additional Information : This paper provided the first experimental evidence showing that physical recruitment of insulin vesicles is necessary in the second phase of insulin release. This publication was vital for a successful BBSRC New Investigators Award and a Wellcome Trust Project Grant recently awarded to Aniko Varadi.