1. Small Molecule Antagonizes Autoinhibition and Activates AMP-activated Protein Kinase in Cells.
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Tao Pang, Zhen-Shan Zhang, Min Gu, Bei-Ying Qiu, Li-Fang Yu, Peng-Rong Cao, Wei Shao, Ming-Bo Su, Jing-Ya Li, Fa-Jun Nan, and Jia Lit
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BIOCHEMISTRY , *PROTEIN kinases , *CELLS , *DIABETES , *OBESITY , *PHOSPHORYLATION - Abstract
AMP-activated protein kinase (AMPK) serves as an energy sensor and is considered a promising drug target for treatment of type II diabetes and obesity. A previous report has shown that mammalian AMPK al catalytic subunit including autoinhibitory domain was inactive. To test the hypothesis that small molecules can activate AMPK through antagonizing the autoinhibition in a subunits, we screened a chemical library with inactive human a1394 (αl, residues 1-394) and found a novel small-molecule activator, PT1, which dose-dependently activated AMPK α1394, α1335, α2398, and even heterotrimer α1β1γ1. Based on PT1-docked AMPK α1 subunit structure model and different mutations, we found PT1 might interact with Glu-96 and Lys156 residues near the autoinhibitory domain and directly relieve autoinhibition. Further studies using L6 myotubes showed that the phosphorylation of AMPK and its downstream substrate, acetyl-CoA carboxylase, were dose-dependently and time-dependently increased by PT1 without an increase in cellular AMP:ATP ratio. Moreover, in HeLa cells deficient in LKB1, PT1 enhanced AMPK phosphorylation, which can be inhibited by the calcium/calmodulin-dependent protein kinase kinases inhibitor STO-609 and AMPK inhibitor compound C. PT1 also lowered hepatic lipid content in a dose-dependent manner through AMPK activation in HepG2 cells, and this effect was diminished by compound C. Taken together, these data indicate that this small-molecule activator may directly activate AMPK via antagonizing the autoinhibition in vitro and in cells. This compound highlights the effort to discover novel AMPK activators and can be a useful tool for elucidating the mechanism responsible for conformational change and autoinhibitory regulation of AMPK. [ABSTRACT FROM AUTHOR]
- Published
- 2008
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