Metabolic Regulation of the Pancreatic Beta-Cell ATP-Sensitive K+ Channel

A Pas de Deux

  1. Andrei Tarasov,
  2. Julien Dusonchet and
  3. Frances Ashcroft
  1. University Laboratory of Physiology, University of Oxford, Oxford, U.K
  1. Address correspondence and reprint requests to Frances M. Ashcroft, University Laboratory of Physiology, Parks Rd., Oxford OX1 3PT, U.K. E-mail: frances.ashcroft{at}physiol.ox.ac.uk

Abstract

Closure of ATP-sensitive K+ channels (KATP channels) is a key step in glucose-stimulated insulin secretion. The precise mechanism(s) by which glucose metabolism regulates KATP channel activity, however, remains controversial. It is widely believed that the principal determinants are the intracellular concentrations of the metabolic ligands, ATP and ADP, which have opposing actions on KATP channels, with ATP closing and MgADP opening the channel. However, the sensitivity of the channel to these nucleotides in the intact cell, and their relative contribution to the regulation of channel activity, remains unclear. The precise role of phosphoinositides and long-chain acyl-CoA esters, which are capable of modulating the channel ATP sensitivity, is also uncertain. Furthermore, it is still a matter of debate whether it is changes in the concentration of ATP, of MgADP, or of other agents, which couples glucose metabolism to KATP channel activity. In this article, we review current knowledge of the metabolic regulation of the KATP channel and provide evidence that MgADP (or MgATP hydrolysis), acting at the regulatory subunit of the channel, shifts the ATP concentration-response curve into a range in which the channel pore can respond to dynamic changes in cytosolic ATP. This metabolic pas de deux orchestrates the pivotal role of ATP in metabolic regulation of the KATP channel.

Footnotes

  • A.T. and J.D. contributed equally to this work.

    This article is based on a presentation at a symposium. The symposium and the publication of this article were made possible by an unrestricted educational grant from Servier.

    • Accepted May 26, 2004.
    • Received March 17, 2004.
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