The University of Southampton
University of Southampton Institutional Repository

Plasma membrane electron transport in pancreatic ?-cells is mediated in part by NQO1

Plasma membrane electron transport in pancreatic ?-cells is mediated in part by NQO1
Plasma membrane electron transport in pancreatic ?-cells is mediated in part by NQO1
Plasma membrane electron transport (PMET), a cytosolic/plasma membrane analog of mitochondrial electron transport, is a ubiquitous system of cytosolic and plasma membrane oxidoreductases that oxidizes cytosolic NADH and NADPH and passes electrons to extracellular targets. While PMET has been shown to play an important role in a variety of cell types, no studies exist to evaluate its function in insulin-secreting cells. Here we demonstrate the presence of robust PMET activity in primary islets and clonal ?-cells, as assessed by the reduction of the plasma membrane-impermeable dyes WST-1 and ferricyanide. Because the degree of metabolic function of ?-cells (reflected by the level of insulin output) increases in a glucose-dependent manner between 4 and 10 mM glucose, PMET was evaluated under these conditions. PMET activity was present at 4 mM glucose and was further stimulated at 10 mM glucose. PMET activity at 10 mM glucose was inhibited by the application of the flavoprotein inhibitor diphenylene iodonium and various antioxidants. Overexpression of cytosolic NAD(P)H-quinone oxidoreductase (NQO1) increased PMET activity in the presence of 10 mM glucose while inhibition of NQO1 by its inhibitor dicoumarol abolished this activity. Mitochondrial inhibitors rotenone, antimycin A, and potassium cyanide elevated PMET activity. Regardless of glucose levels, PMET activity was greatly enhanced by the application of aminooxyacetate, an inhibitor of the malate-aspartate shuttle. We propose a model for the role of PMET as a regulator of glycolytic flux and an important component of the metabolic machinery in ?-cells.

0193-1849
E105-E112
Gray, Joshua P.
87bb062f-a135-4f9b-9b65-02ade9a7fece
Eisen, Timothy
65b0bba2-91d6-4b6e-acf4-6fbe5062f9a8
Cline, Gary W.
46e297fd-92fe-4853-a5c9-b4bdb5ad5952
Smith, Peter J.S.
003de469-9420-4f12-8f0e-8e8d76d28d6c
Heart, Emma
f8b99fd2-026e-43cd-9db6-67edd6d18c98
Gray, Joshua P.
87bb062f-a135-4f9b-9b65-02ade9a7fece
Eisen, Timothy
65b0bba2-91d6-4b6e-acf4-6fbe5062f9a8
Cline, Gary W.
46e297fd-92fe-4853-a5c9-b4bdb5ad5952
Smith, Peter J.S.
003de469-9420-4f12-8f0e-8e8d76d28d6c
Heart, Emma
f8b99fd2-026e-43cd-9db6-67edd6d18c98

Gray, Joshua P., Eisen, Timothy, Cline, Gary W., Smith, Peter J.S. and Heart, Emma (2011) Plasma membrane electron transport in pancreatic ?-cells is mediated in part by NQO1. American Journal of Physiology: Endocrinology and Metabolism, 301, E105-E112. (doi:10.1152/ajpendo.00673.2010). (PMID:21505151)

Record type: Article

Abstract

Plasma membrane electron transport (PMET), a cytosolic/plasma membrane analog of mitochondrial electron transport, is a ubiquitous system of cytosolic and plasma membrane oxidoreductases that oxidizes cytosolic NADH and NADPH and passes electrons to extracellular targets. While PMET has been shown to play an important role in a variety of cell types, no studies exist to evaluate its function in insulin-secreting cells. Here we demonstrate the presence of robust PMET activity in primary islets and clonal ?-cells, as assessed by the reduction of the plasma membrane-impermeable dyes WST-1 and ferricyanide. Because the degree of metabolic function of ?-cells (reflected by the level of insulin output) increases in a glucose-dependent manner between 4 and 10 mM glucose, PMET was evaluated under these conditions. PMET activity was present at 4 mM glucose and was further stimulated at 10 mM glucose. PMET activity at 10 mM glucose was inhibited by the application of the flavoprotein inhibitor diphenylene iodonium and various antioxidants. Overexpression of cytosolic NAD(P)H-quinone oxidoreductase (NQO1) increased PMET activity in the presence of 10 mM glucose while inhibition of NQO1 by its inhibitor dicoumarol abolished this activity. Mitochondrial inhibitors rotenone, antimycin A, and potassium cyanide elevated PMET activity. Regardless of glucose levels, PMET activity was greatly enhanced by the application of aminooxyacetate, an inhibitor of the malate-aspartate shuttle. We propose a model for the role of PMET as a regulator of glycolytic flux and an important component of the metabolic machinery in ?-cells.

This record has no associated files available for download.

More information

e-pub ahead of print date: April 2011
Published date: July 2011
Organisations: Faculty of Natural and Environmental Sciences

Identifiers

Local EPrints ID: 201165
URI: http://eprints.soton.ac.uk/id/eprint/201165
ISSN: 0193-1849
PURE UUID: e046ff8e-3b89-4440-92d1-6402cf84382d
ORCID for Peter J.S. Smith: ORCID iD orcid.org/0000-0003-4400-6853

Catalogue record

Date deposited: 28 Oct 2011 10:47
Last modified: 15 Mar 2024 03:39

Export record

Altmetrics

Contributors

Author: Joshua P. Gray
Author: Timothy Eisen
Author: Gary W. Cline
Author: Emma Heart

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×