title: Coregulated ataxia telangiectasia-mutated and casein kinase sites modulate cAMP-response element-binding protein-coactivator interactions in response to DNA damage.
abstract: The cyclic AMP-response element-binding protein (CREB) is a bZIP family transcription factor implicated as an oncoprotein and neuron survival factor. CREB is activated in response to cellular stimuli, including cAMP and Ca(2+), via phosphorylation of Ser-133, which promotes interaction between the kinase-inducible domain (KID) of CREB and the KID-interacting domain of CREB-binding protein (CBP). We previously demonstrated that the interaction between CREB and CBP is inhibited by DNA-damaging stimuli through a mechanism whereby CREB is phosphorylated by the ataxia telangiectasia-mutated (ATM) protein kinase. We now show that the ATM phosphorylation sites in CREB are functionally intertwined with a cluster of coregulated casein kinase (CK) sites. We demonstrate that DNA damage-induced phosphorylation of CREB occurs in three steps. The initial event in the CREB phosphorylation cascade is the phosphorylation of Ser-111, which is carried out by CK1 and CK2 under basal conditions and by ATM in response to ionizing radiation. The phosphorylation of Ser-111 triggers the CK2-dependent phosphorylation of Ser-108 and the CK1-dependent phosphorylation of Ser-114 and Ser-117. The phosphorylation of Ser-114 and Ser-117 by CK1 then renders CREB permissive for ATM-dependent phosphorylation on Ser-121. Mutation of Ser-121 alone abrogates ionizing radiation-dependent repression of CREB-CBP complexes, which can be recapitulated using a CK1 inhibitor. Our findings outline a complex mechanism of CREB phosphorylation in which coregulated ATM and CK sites control CREB transactivation potential by modulating its CBP-binding affinity. The coregulated ATM and CK sites identified in CREB may constitute a signaling motif that is common to other DNA damage-regulated substrates.
authors.affiliation: Molecular and Cellular Pharmacology Program, Department of Pharmacology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53706.
authors.forename: Naval P
authors.initials: NP
authors.lastname: Shanware
authors.forename: Anthony T
authors.initials: AT
authors.lastname: Trinh
authors.forename: Leah M
authors.initials: LM
authors.lastname: Williams
authors.forename: Randal S
authors.initials: RS
authors.lastname: Tibbetts
mesh_terms: D000818:Animals; D064007:Ataxia Telangiectasia Mutated Proteins; D001665:Binding Sites; D050882:CREB-Binding Protein / Q000378:metabolism; D047389:Casein Kinase I / Q000378:metabolism; D047390:Casein Kinase II / Q000378:metabolism; D047388:Casein Kinases / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002460:Cell Line; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism*; D004249:DNA Damage; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006801:Humans; D051379:Mice; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D015533:Transcriptional Activation; D014162:Transfection; D025521:Tumor Suppressor Proteins / Q000378:metabolism*
chemical_list: D018797:Cell Cycle Proteins; D017362:Cyclic AMP Response Element-Binding Protein; D004268:DNA-Binding Proteins; D025521:Tumor Suppressor Proteins; D050882:CREB-Binding Protein; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C576325:Atm protein, mouse; D047389:Casein Kinase I; D047390:Casein Kinase II; D047388:Casein Kinases; D017346:Protein Serine-Threonine Kinases