Structural basis of AMPK regulation by small molecule activators

Abstract

AMP-activated protein kinase (AMPK) plays a major role in regulating cellular energy balance by sensing and responding to increases in AMP/ADP concentration relative to ATP. Binding of AMP causes allosteric activation of the enzyme and binding of either AMP or ADP promotes and maintains the phosphorylation of threonine 172 within the activation loop of the kinase. AMPK has attracted widespread interest as a potential therapeutic target for metabolic diseases including type 2 diabetes and, more recently, cancer. A number of direct AMPK activators have been reported as having beneficial effects in treating metabolic diseases, but there has been no structural basis for activator binding to AMPK. Here we present the crystal structure of human AMPK in complex with a small molecule activator that binds at a site between the kinase domain and the carbohydrate-binding module, stabilising the interaction between these two components. The nature of the activator-binding pocket suggests the involvement of an additional, as yet unidentified, metabolite in the physiological regulation of AMPK. Importantly, the structure offers new opportunities for the design of small molecule activators of AMPK for treatment of metabolic disorders.

Adipocyte-specific deletion of Ip6k1 reduces diet-induced obesity by enhancing AMPK-mediated thermogenesis

“…Accordingly, active research is ongoing to identify small-molecule activators of AMPK (82,83). However, to our knowledge, physiological small-molecule activators of AMPK, other than AMP, are not known.…”

Antifungal drug itraconazole targets VDAC1 to modulate the AMPK/mTOR signaling axis in endothelial cells

“…A769662 is a direct and specific activator of AMPK, which binds in the interface between the AMPK α-and β-subunits and allosterically activates the complex (32). We therefore tested A769662 in HUVEC and found that it inhibited proliferation with an IC 50 of 73 μM (±8.34; SEM) (SI Appendix, Fig.…”

Adenosine Monophosphate–Activated Kinase and Its Key Role in Catabolism: Structure, Regulation, Biological Activity, and Pharmacological Activation

“…Only AMP binding at CBS site 3 is shown (marked as AMP-3). Reprinted with permission from Macmillan Publishers Ltd: [Nature] (Xiao et al, 2013), (http://creativecommons.org/licenses/by/3.0/legalcode). (B) The a-subunit is a 550 amino acid long catalytic subunit and is composed of the kinase domain, a-linker region, the C-terminal b/g-subunit interacting domain (a-CTD), and a nuclear export signal.…”

“…Additionally, this region is also involved in the interaction of the a-subunit kinase domain with the regulatory fragment, which consists of the C-terminal domains of the a-and b-subunits and all domains of the g-subunit (Momcilovic et al, 2008;Xiao et al, 2011Xiao et al, , 2013. More recently, the CBM region was also shown to be involved in protecting AMPK from cellular phosphatases (Xiao et al, 2013), such as human protein phosphatase-2ca (PP2Ca) (Davies et al, 1995). In fact, the CBM region binds to the N-lobe of the kinase domain and is also connected to the regulatory fragment (Xiao et al, 2013).…”

“…More recently, the CBM region was also shown to be involved in protecting AMPK from cellular phosphatases (Xiao et al, 2013), such as human protein phosphatase-2ca (PP2Ca) (Davies et al, 1995). In fact, the CBM region binds to the N-lobe of the kinase domain and is also connected to the regulatory fragment (Xiao et al, 2013). It has been suggested that an AMPK activator, namely, compound 991, promotes the interaction between the kinase and CBM region to protect active AMPK against dephosphorylation (Xiao et al, 2013).…”