The role of AMPK and mTOR in nutrient sensing in pancreatic beta-cells.

Published

Journal Article

The AMP-activated protein kinase (AMPK) is a central regulator of the energy status of the cell, based on its unique ability to respond directly to fluctuations in the ratio of AMP:ATP. Because glucose and amino acids stimulate insulin release from pancreatic beta-cells by the regulation of metabolic intermediates, AMPK represents an attractive candidate for control of beta-cell function. Here, we show that inhibition of AMPK in beta-cells by high glucose inversely correlates with activation of the mammalian Target of Rapamycin (mTOR) pathway, another cellular sensor for nutritional conditions. Forced activation of AMPK by AICAR, phenformin, or oligomycin significantly blocked phosphorylation of p70S6K, a downstream target of mTOR, in response to the combination of glucose and amino acids. Amino acids also suppressed the activity of AMPK, and this at a minimum required the presence of leucine and glutamine. It is unlikely that the ability of AMPK to sense both glucose and amino acids plays a role in regulation of insulin secretion, as inhibition of AMPK by amino acids did not influence insulin secretion. Moreover, activation of AMPK by AICAR or phenformin did not antagonize glucose-stimulated insulin secretion, and insulin secretion was also unaffected in response to suppression of AMPK activity by expression of a dominant negative AMPK construct (K45R). Taken together, these results suggest that the inhibition of AMPK activity by glucose and amino acids might be an important component of the mechanism for nutrient-stimulated mTOR activity but not insulin secretion in the beta-cell.

Full Text

Duke Authors

Cited Authors

  • Gleason, CE; Lu, D; Witters, LA; Newgard, CB; Birnbaum, MJ

Published Date

  • April 6, 2007

Published In

Volume / Issue

  • 282 / 14

Start / End Page

  • 10341 - 10351

PubMed ID

  • 17287212

Pubmed Central ID

  • 17287212

International Standard Serial Number (ISSN)

  • 0021-9258

Digital Object Identifier (DOI)

  • 10.1074/jbc.M610631200

Language

  • eng

Conference Location

  • United States