Use of Cells Expressing γ Subunit Variants to Identify Diverse Mechanisms of AMPK Activation

Abstract

SummaryA wide variety of agents activate AMPK, but in many cases the mechanisms remain unclear. We generated isogenic cell lines stably expressing AMPK complexes containing AMP-sensitive (wild-type, WT) or AMP-insensitive (R531G) γ2 variants. Mitochondrial poisons such as oligomycin and dinitrophenol only activated AMPK in WT cells, as did AICAR, 2-deoxyglucose, hydrogen peroxide, metformin, phenformin, galegine, troglitazone, phenobarbital, resveratrol, and berberine. Excluding AICAR, all of these also inhibited cellular energy metabolism, shown by increases in ADP:ATP ratio and/or by decreases in cellular oxygen uptake measured using an extracellular flux analyzer. By contrast, A769662, the Ca2+ ionophore, A23187, osmotic stress, and quercetin activated both variants to varying extents. A23187 and osmotic stress also increased cytoplasmic Ca2+, and their effects were inhibited by STO609, a CaMKK inhibitor. Our approaches distinguish at least six different mechanisms for AMPK activation and confirm that the widely used antidiabetic drug metformin activates AMPK by inhibiting mitochondrial respiration.

Commonly used fertility drugs, a diet supplement, and stress force AMPK-dependent block of stemness and development in cultured mammalian embryos

“…The following food groups and food extracts have high AMPKactivating capacity: resveratrol (red grape skin extract) [114][115][116][117][118], nootkatone (grapefruit extract) [119], ajoene (garlic extract) [120], BDIM (cruciferous vegetable extract) [19,121], and many others [122]. Medicines activate AMPK including Asa [16], Met [35], phenformin [123,124], rosiglitazone, and phenobarbital [125,126], and there may be others.…”

Pentamethylquercetin generates beneficial effects in monosodium glutamate-induced obese mice and C2C12 myotubes by activating AMP-activated protein kinase

“…As a structural analogue of PMQ, quercetin was able to inhibit mitochondrial F0F1-ATPase activity and increase the AMP:ATP ratio, further activating AMPK [46]. Another study showed that quercetin activated AMPK by AMP-dependent and AMP-independent mechanisms [47]. Additionally, quercetin has been shown to activate AMPK via activation of reactive oxygen species generation and inositol-requiring enzyme 1α (IRE1α) RNase [48,49].…”

Role of Deleted in Breast Cancer 1 (DBC1) Protein in SIRT1 Deacetylase Activation Induced by Protein Kinase A and AMP-activated Protein Kinase

“…Therefore, we tested whether short treatments (1-2 h) with AMPK activators can induce an increase in SIRT1 activity without changes in the intracellular levels of NAD ϩ . To test our hypothesis, we used several AMPK activators: A769662 (52), AICAR (53), and oligomycin (54). We found that a short incubation of A549 cells with all these AMPK activators promoted SIRT1 activation (Fig.…”