Concurrent regulation of AMP-activated protein kinase and SIRT1 in mammalian cells.
Level 5 - mechanism / opinion, no new human data
In vitro laboratory study in a cell line (bench research)
PubMed 19071085 · doi:10.1016/j.bbrc.2008.11.130
What was done
Researchers investigated the relationship between AMP-activated protein kinase (AMPK) activity and SIRT1 in human hepatoma (HepG2) cells. Cells were treated with high (25 mM) versus physiological (5 mM) glucose for 6 hours, pyruvate (0.1 and 1 mM) for 2 hours, or the putative SIRT1 activators resveratrol and quercetin. Outcomes measured were AMPK (Thr 172) and acetyl-CoA carboxylase (ACC, Ser 79) phosphorylation, SIRT1 abundance and activity, lactate release, and AMP/ATP ratios.
What was found
Incubation with 25 mM versus 5 mM glucose reduced AMPK (Thr 172) and ACC (Ser 79) phosphorylation, increased lactate release, and decreased SIRT1 abundance and activity. Pyruvate (0.1 and 1 mM) increased AMPK phosphorylation and SIRT1 abundance and activity. Resveratrol and quercetin also increased AMPK phosphorylation. None of the treatments (high/low glucose, pyruvate, or resveratrol) significantly altered cellular AMP/ATP ratios. The abstract reports directional changes without numeric values or effect sizes.
Why it matters
This study provides evidence that nutrient-sensing pathways involving AMPK and SIRT1 co-vary in response to glucose and pyruvate in liver-derived cells, pointing toward redox state rather than adenine nucleotide energy charge as a shared regulator.
Limits
The study is restricted to an in vitro immortalized cell model (HepG2 hepatoma), which may not accurately reflect normal hepatic tissue or in vivo human physiology. The abstract provides no specific quantitative values, sample sizes, or error bounds, and the exact directional causality between SIRT1 and AMPK was not established.
Cited by
- supports Quercetin activates AMPK, an enzyme in longevity pathways.