AMP-activated protein kinase phosphorylates transcription factors of the CREB family.
AMP-activated protein kinase (AMPK) has been identified as a regulator of gene transcription, increasing mitochondrial proteins of oxidative metabolism as well as hexokinase expression in skeletal muscle. In mice, muscle-specific knockout of LKB1, a component of the upstream kinase of AMPK, prevents contraction- and 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside (AICAR)-induced activation of AMPK in skeletal muscle, and the increase in hexokinase II protein that is normally observed with chronic AICAR activation of AMPK. Since previous reports show a cAMP response element in the promoter region of the hexokinase II gene, we hypothesized that the cAMP-response element (CRE) binding protein (CREB) family of transcription factors could be targets of AMPK. Using radioisotopic kinase assays, we found that recombinant and rat liver and muscle AMPK phosphorylated CREB1 at the same site as cAMP-dependent protein kinase (PKA). AMPK was also found to phosphorylate activating transcription factor 1 (ATF1), CRE modulator (CREM), and CREB-like 2 (CREBL2), but not ATF2. Treatment of HEK-293 cells stably transfected with a CREB-driven luciferase reporter with AICAR increased luciferase activity approximately threefold over a 24-h time course. This increase was blocked with compound C, an AMPK inhibitor. In addition, AICAR-induced activation of AMPK in incubated rat epitrochlearis muscles resulted in an increase in both phospho-acetyl-CoA carboxylase and phospho-CREB. We conclude that CREB and related proteins are direct downstream targets for AMPK and are therefore likely involved in mediating some effects of AMPK on expression of genes having a CRE in their promoters.
Dept. of Physiology and Developmental Biology, 545 WIDB, Brigham Young Univ., Provo, UT 84602, USA.
D M
DM
Thomson
S T
ST
Herway
N
N
Fillmore
H
H
Kim
J D
JD
Brown
J R
JR
Barrow
W W
WW
Winder
D055372:AMP-Activated Protein Kinases; D000103:Acetyl-CoA Carboxylase / Q000378:metabolism; D051697:Activating Transcription Factor 1 / Q000378:metabolism; D000620:Aminoimidazole Carboxamide / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D002460:Cell Line; D051786:Cyclic AMP Response Element Modulator / Q000378:metabolism; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004789:Enzyme Activation; D004790:Enzyme Induction; D017930:Genes, Reporter; D006593:Hexokinase / Q000096:biosynthesis; D006801:Humans; D008099:Liver / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D008156:Luciferases; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D009097:Multienzyme Complexes / Q000037:antagonists & inhibitors / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D011720:Pyrazoles / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D011994:Recombinant Proteins / Q000378:metabolism; D012265:Ribonucleotides / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors; D014162:Transfection
D051697:Activating Transcription Factor 1; C497100:Atf1 protein, mouse; C508137:Creb1 protein, rat; C492004:Creb1 protein, mouse; C497411:Crem protein, mouse; D017362:Cyclic AMP Response Element-Binding Protein; D009097:Multienzyme Complexes; D047428:Protein Kinase Inhibitors; D011720:Pyrazoles; D011743:Pyrimidines; D011994:Recombinant Proteins; D012265:Ribonucleotides; C516138:dorsomorphin; D051786:Cyclic AMP Response Element Modulator; D000620:Aminoimidazole Carboxamide; D008156:Luciferases; D006593:Hexokinase; D017346:Protein Serine-Threonine Kinases; C491654:Stk11 protein, mouse; D017868:Cyclic AMP-Dependent Protein Kinases; D055372:AMP-Activated Protein Kinases; D000103:Acetyl-CoA Carboxylase; C031143:AICA ribonucleotide