SIRT1 modulation of the acetylation status, cytosolic localization, and activity of LKB1. Possible role in AMP-activated protein kinase activation

J Biol Chem. 2008 Oct 10;283(41):27628-35. doi: 10.1074/jbc.M805711200. Epub 2008 Aug 7.

Abstract

SIRT1, a histone/protein deacetylase, and AMP-activated protein kinase (AMPK) are key enzymes responsible for longevity and energy homeostasis. We examined whether a mechanistic connection exists between these molecules that involves the major AMPK kinase LKB1. Initial studies demonstrated that LKB1 is acetylated in cultured (HEK293T) cells, mouse white adipose tissue, and rat liver. In the 293T cells, SIRT1 overexpression diminished lysine acetylation of LKB1 and concurrently increased its activity, cytoplasmic/nuclear ratio, and association with the LKB1 activator STRAD. In contrast, short hairpin RNA for SIRT1, where studied, had opposite effects on these parameters. Mass spectrometric analysis established that acetylation of LKB1 occurs on multiple, but specific, lysine residues; however, only mutation of lysine 48 to arginine, which mimics deacetylation, reproduced all of the effects of activated SIRT1. SIRT1 also affected downstream targets of LKB1. Thus its overexpression increased AMPK and acetyl-CoA carboxylase phosphorylation, and conversely, RNA interference-mediated SIRT1 knockdown reduced AMPK phosphorylation and that of another LKB1 target MARK1. Consistent with the results in cultured cells, total LKB1 lysine acetylation was decreased by 60% in the liver of 48-h starved rats compared with starved-refed rats, and this was associated with modest but significant increases in both LKB1 and AMPK activities. These results suggest that LKB1 deacetylation is regulated by SIRT1 and that this in turn influences its intracellular localization, association with STRAD, kinase activity, and ability to activate AMPK.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetylation
  • Active Transport, Cell Nucleus / genetics
  • Adaptor Proteins, Vesicular Transport / genetics
  • Adaptor Proteins, Vesicular Transport / metabolism*
  • Animals
  • Cell Line, Tumor
  • Cell Nucleus / enzymology*
  • Cell Nucleus / genetics
  • Cyclic AMP-Dependent Protein Kinases / genetics
  • Cyclic AMP-Dependent Protein Kinases / metabolism*
  • Cytosol / enzymology*
  • Enzyme Activation / genetics
  • Humans
  • Liver / enzymology
  • Mice
  • Protein-Serine-Threonine Kinases / genetics
  • Protein-Serine-Threonine Kinases / metabolism*
  • RNA Interference
  • Rats
  • Rats, Sprague-Dawley
  • Sirtuin 1
  • Sirtuins / genetics
  • Sirtuins / metabolism*
  • Starvation / enzymology
  • Starvation / genetics

Substances

  • Adaptor Proteins, Vesicular Transport
  • STRAD protein, human
  • MARK1 protein, human
  • STK11 protein, human
  • Protein-Serine-Threonine Kinases
  • Stk11 protein, rat
  • Cyclic AMP-Dependent Protein Kinases
  • SIRT1 protein, human
  • Sirt1 protein, rat
  • Sirtuin 1
  • Sirtuins