6b2e
Structure of full length human AMPK (a2b2g1) in complex with a small molecule activator SC4.
Structural highlights
FunctionAAPK2_HUMAN Catalytic subunit of AMP-activated protein kinase (AMPK), an energy sensor protein kinase that plays a key role in regulating cellular energy metabolism. In response to reduction of intracellular ATP levels, AMPK activates energy-producing pathways and inhibits energy-consuming processes: inhibits protein, carbohydrate and lipid biosynthesis, as well as cell growth and proliferation. AMPK acts via direct phosphorylation of metabolic enzymes, and by longer-term effects via phosphorylation of transcription regulators. Also acts as a regulator of cellular polarity by remodeling the actin cytoskeleton; probably by indirectly activating myosin. Regulates lipid synthesis by phosphorylating and inactivating lipid metabolic enzymes such as ACACA, ACACB, GYS1, HMGCR and LIPE; regulates fatty acid and cholesterol synthesis by phosphorylating acetyl-CoA carboxylase (ACACA and ACACB) and hormone-sensitive lipase (LIPE) enzymes, respectively. Regulates insulin-signaling and glycolysis by phosphorylating IRS1, PFKFB2 and PFKFB3. AMPK stimulates glucose uptake in muscle by increasing the translocation of the glucose transporter SLC2A4/GLUT4 to the plasma membrane, possibly by mediating phosphorylation of TBC1D4/AS160. Regulates transcription and chromatin structure by phosphorylating transcription regulators involved in energy metabolism such as CRTC2/TORC2, FOXO3, histone H2B, HDAC5, MEF2C, MLXIPL/ChREBP, EP300, HNF4A, p53/TP53, SREBF1, SREBF2 and PPARGC1A. Acts as a key regulator of glucose homeostasis in liver by phosphorylating CRTC2/TORC2, leading to CRTC2/TORC2 sequestration in the cytoplasm. In response to stress, phosphorylates 'Ser-36' of histone H2B (H2BS36ph), leading to promote transcription. Acts as a key regulator of cell growth and proliferation by phosphorylating TSC2, RPTOR and ATG1: in response to nutrient limitation, negatively regulates the mTORC1 complex by phosphorylating RPTOR component of the mTORC1 complex and by phosphorylating and activating TSC2. In response to nutrient limitation, promotes autophagy by phosphorylating and activating ULK1. AMPK also acts as a regulator of circadian rhythm by mediating phosphorylation of CRY1, leading to destabilize it. May regulate the Wnt signaling pathway by phosphorylating CTNNB1, leading to stabilize it. Also phosphorylates CFTR, EEF2K, KLC1, NOS3 and SLC12A1.[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] Publication Abstract from PubMedThe AMP-activated protein kinase (AMPK) alphabetagamma heterotrimer regulates cellular energy homeostasis with tissue-specific isoform distribution. Small-molecule activation of skeletal muscle alpha2beta2 AMPK complexes may prove a valuable treatment strategy for type 2 diabetes and insulin resistance. Herein, we report the small-molecule SC4 is a potent, direct AMPK activator that preferentially activates alpha2 complexes and stimulates skeletal muscle glucose uptake. In parallel with the term secretagog, we propose "importagog" to define a substance that induces or augments cellular uptake of another substance. Three-dimensional structures of the glucose importagog SC4 bound to activated alpha2beta2gamma1 and alpha2beta1gamma1 complexes reveal binding determinants, in particular a key interaction between the SC4 imidazopyridine 4'-nitrogen and beta2-Asp111, which provide a design paradigm for beta2-AMPK therapeutics. The alpha2beta2gamma1/SC4 structure reveals an interaction between a beta2 N-terminal alpha helix and the alpha2 autoinhibitory domain. Our results provide a structure-function guide to accelerate development of potent, but importantly tissue-specific, beta2-AMPK therapeutics. Structural Determinants for Small-Molecule Activation of Skeletal Muscle AMPK alpha2beta2gamma1 by the Glucose Importagog SC4.,Ngoei KRW, Langendorf CG, Ling NXY, Hoque A, Varghese S, Camerino MA, Walker SR, Bozikis YE, Dite TA, Ovens AJ, Smiles WJ, Jacobs R, Huang H, Parker MW, Scott JW, Rider MH, Foitzik RC, Kemp BE, Baell JB, Oakhill JS Cell Chem Biol. 2018 Apr 12. pii: S2451-9456(18)30110-7. doi:, 10.1016/j.chembiol.2018.03.008. PMID:29657085[13] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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