Mechanism and cellular actions of the potent AMPK inhibitor BAY-3827

Inhibition of AMP-activated protein kinase (AMPK) is increasingly being explored for its therapeutic potential in some diseases, including certain types of cancers. However, AMPK-inhibitory tool compounds have largely been limited to compound C/dorsomorphin and SBI-0206965, both of which display numerous off-target effects and blocking AMPK-independent metabolic processes. Here we describe molecular insights and cellular actions/utility of a recently identified potent AMPK inhibitor BAY-3827. Sequence analysis of highly/lowly-inhibited kinases by BAY-3827, based on in vitro kinase selectivity profiling, predicted key conserved residues involved in the compound-inhibitory effect. A co-crystal structure of the AMPK kinase domain (KD)-BAY-3827 complex resolved at 2.5 Å in comparison with previously reported KD-inhibitor structures, revealed an overlapping binding site in the ATP-binding pocket and common αC helix-out conformations. We identified distinct features of BAY-3827-bound structure which involve a disulfide bridge between αD helix Cys106 and activation loop residue Cys174. This may help to stabilize AMPK conformation upon BAY-3827 binding, where the position of activation loop Asn162 leads the DFG motif Phe158 to adopt a conformation facing the C-terminal kinase lobe displacing His137, leading to a broken regulatory spine and an inactive kinase state. BAY-3827 at 2.5-5 μM, but not structurally resembling inactive BAY-974, fully blocked AMPK activator (MK-8722)-mediated phosphorylation of ACC1 and inhibition of lipogenesis in hepatocytes. Unbiased transcriptome analysis in MK-8722-treated wild-type and AMPK-null hepatocytes revealed that >30% of MK-8722-stimulated AMPK-dependent genes could be downregulated by 5 μM BAY-3827. Based on its greater selectivity and potency substantiated by comprehensive molecular/cellular investigations. BAY-3827 is a powerful tool to delineate AMPK functions.