Glycogen synthase kinase 3 phosphorylates Jun family members in vitro and negatively regulates their transactivating potential in intact cells.
Expression of immediate-early genes involving the 12-O-tetradecanoyl phorbol 13-acetate (TPA)-responsive element (TRE) is modulated by post-translational modification of pre-existing activator protein 1 (AP-1) constituents. One of the components of AP-1, c-Jun, has been shown to be phosphorylated by glycogen synthase kinase 3 (GSK-3) in vitro in a region proximal to the DNA-binding domain, resulting in decreased DNA binding. Here, we have used transient transfection to show that AP-1 activity is inhibitable by coexpression of GSK-3 in intact cells. Furthermore, we show that the c-Jun-related proteins JunD and JunB are subject to similar regulation by GSK-3 in intact cells. Comparison of tryptic phosphopeptide maps of the three Jun proteins incubated with GSK-3 in vitro with maps of the same proteins immunoprecipitated from 32P-labelled cells indicates similar sites of phosphorylation. Together, these data support the hypothesis that GSK-3 is an important regulator of AP-1 activity in vivo.
Ludwig Institute for Cancer Research, London, UK.
E
E
Nikolakaki
P J
PJ
Coffer
R
R
Hemelsoet
J R
JR
Woodgett
L H
LH
Defize
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002460:Cell Line; D002522:Chlorocebus aethiops; D038341:Glycogen Synthase Kinases; D066298:In Vitro Techniques; D051379:Mice; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D015533:Transcriptional Activation
D010455:Peptides; D010750:Phosphoproteins; D016755:Proto-Oncogene Proteins c-jun; D011994:Recombinant Proteins; D011494:Protein Kinases; D038341:Glycogen Synthase Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases