Glucose and cAMP regulate the L-type pyruvate kinase gene by phosphorylation/dephosphorylation of the carbohydrate response element binding protein.
Recently we purified and identified a previously uncharacterized transcription factor from rat liver binding to the carbohydrate responsive element of the L-type pyruvate kinase (L-PK) gene. This factor was named carbohydrate responsive element binding protein (ChREBP). ChREBP, essential for L-PK gene transcription, is activated by high glucose and inhibited by cAMP. Here, we demonstrated that (i) nuclear localization signal and basic helix-loop-helix/leucine-zipper domains of ChREBP were essential for the transcription, and (ii) these domains were the targets of regulation by cAMP and glucose. Among three cAMP-dependent protein kinase phosphorylation sites, Ser(196) and Thr(666) were the target sites. Phosphorylation of the former resulted in inactivation of nuclear import, and that of the latter resulted in loss of the DNA-binding activity and L-PK transcription. On the other hand, glucose activated the nuclear import by dephosphorylation of Ser(196) in the cytoplasm and also stimulated the DNA-binding activity by dephosphorylation of Thr(666) in the nucleus. These results thus reveal mechanisms for regulation of ChREBP and the L-PK transcription by excess carbohydrate and cAMP.
Kawaguchi
T
T
Department of Biochemistry, Dallas Veterans Affairs Medical Center and University of Texas Southwestern Medical Center at Dallas, 4500 South Lancaster Road, Dallas, TX 75223, USA.
Takenoshita
M
M
Kabashima
T
T
Uyeda
K
K
D000595:Amino Acid Sequence; D000818:Animals; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D001665:Binding Sites; D003994:Bucladesine / Q000494:pharmacology; D002193:Cantharidin / Q000494:pharmacology; D050260:Carbohydrate Metabolism; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic; D005947:Glucose / Q000378:metabolism*; D018257:Helix-Loop-Helix Motifs; D007546:Isoquinolines / Q000494:pharmacology; D016350:Leucine Zippers; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors / Q000378:metabolism; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors; D011770:Pyruvate Kinase / Q000235:genetics*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020218:Response Elements; D012694:Serine / Q000235:genetics / Q000378:metabolism; D013347:Subcellular Fractions; D013449:Sulfonamides; D013912:Threonine / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D007546:Isoquinolines; C442825:Mlxipl protein, rat; D047428:Protein Kinase Inhibitors; D013449:Sulfonamides; D014157:Transcription Factors; D013912:Threonine; D012694:Serine; D003994:Bucladesine; D004247:DNA; D000242:Cyclic AMP; D011770:Pyruvate Kinase; D017868:Cyclic AMP-Dependent Protein Kinases; D010749:Phosphoprotein Phosphatases; D002193:Cantharidin; D005947:Glucose; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide