Small molecule antagonizes autoinhibition and activates AMP-activated protein kinase in cells.
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 alpha1 catalytic subunit including autoinhibitory domain was inactive. To test the hypothesis that small molecules can activate AMPK through antagonizing the autoinhibition in alpha subunits, we screened a chemical library with inactive human alpha1(394) (alpha1, residues 1-394) and found a novel small-molecule activator, PT1, which dose-dependently activated AMPK alpha1(394), alpha1(335), alpha2(398), and even heterotrimer alpha1beta1gamma1. Based on PT1-docked AMPK alpha1 subunit structure model and different mutations, we found PT1 might interact with Glu-96 and Lys-156 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 with-out 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.
Pang
Tao
T
National Center for Drug Screening, Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences and Roche R&D Center (China) Ltd., Shanghai 201203, China.
Zhang
Zhen-Shan
ZS
Gu
Min
M
Qiu
Bei-Ying
BY
Yu
Li-Fang
LF
Cao
Peng-Rong
PR
Shao
Wei
W
Su
Ming-Bo
MB
Li
Jing-Ya
JY
Nan
Fa-Jun
FJ
Li
Jia
J
D000091162:AMP-Activated Protein Kinase Kinases; D055372:AMP-Activated Protein Kinases; D000103:Acetyl-CoA Carboxylase / Q000037:antagonists & inhibitors / Q000378:metabolism; D000249:Adenosine Monophosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D001562:Benzimidazoles / Q000737:chemistry / Q000494:pharmacology; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy / Q000201:enzymology; D004734:Energy Metabolism / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D020536:Enzyme Activators / Q000737:chemistry / Q000494:pharmacology*; D006367:HeLa Cells; D006801:Humans; D009097:Multienzyme Complexes / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D032446:Myoblasts / Q000201:enzymology; D053644:Naphthalimides / Q000737:chemistry / Q000494:pharmacology; D009765:Obesity / Q000188:drug therapy / Q000201:enzymology; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D020836:Protein Structure, Quaternary / Q000187:drug effects; D011720:Pyrazoles / Q000737:chemistry / Q000494:pharmacology; D011743:Pyrimidines / Q000737:chemistry / Q000494:pharmacology; D013997:Time Factors
D001562:Benzimidazoles; D020536:Enzyme Activators; D009097:Multienzyme Complexes; D053644:Naphthalimides; D011720:Pyrazoles; D011743:Pyrimidines; C458525:STO 609; C516138:dorsomorphin; D000249:Adenosine Monophosphate; D000255:Adenosine Triphosphate; C526181:PRKAA2 protein, human; D017346:Protein Serine-Threonine Kinases; C109790:STK11 protein, human; D000091162:AMP-Activated Protein Kinase Kinases; D055372:AMP-Activated Protein Kinases; C526180:PRKAA1 protein, human; D000103:Acetyl-CoA Carboxylase