title: Conserved and distinct modes of CREB/ATF transcription factor regulation by PP2A/B56gamma and genotoxic stress.
abstract: Activating transcription factor 1 (ATF1) and the closely related proteins CREB (cyclic AMP resonse element binding protein) and CREM (cyclic AMP response element modulator) constitute a subfamily of bZIP transcription factors that play critical roles in the regulation of cellular growth, metabolism, and survival. Previous studies demonstrated that CREB is phosphorylated on a cluster of conserved Ser residues, including Ser-111 and Ser-121, in response to DNA damage through the coordinated actions of the ataxia-telangiectasia-mutated (ATM) protein kinase and casein kinases 1 and 2 (CK1/2). Here, we show that DNA damage-induced phosphorylation by ATM is a general feature of CREB and ATF1. ATF1 harbors a conserved ATM/CK cluster that is constitutively and stoichiometrically phosphorylated by CK1 and CK2 in asynchronously growing cells. Exposure to DNA damage further induced ATF1 phosphorylation on Ser-51 by ATM in a manner that required prior phosphorylation of the upstream CK residues. Hyperphosphorylated ATF1 showed a 4-fold reduced affinity for CREB-binding protein. We further show that PP2A, in conjunction with its targeting subunit B56gamma, antagonized ATM and CK1/2-dependent phosphorylation of CREB and ATF1 in cellulo. Finally, we show that CK sites in CREB are phosphorylated during cellular growth and that phosphorylation of these residues reduces the threshold of DNA damage required for ATM-dependent phosphorylation of the inhibitory Ser-121 residue. These studies define overlapping and distinct modes of CREB and ATF1 regulation by phosphorylation that may ensure concerted changes in gene expression mediated by these factors.
authors: Department of Pharmacology, Program in Molecular and Cellular Pharmacology and Molecular and Environmental and Toxicology Center, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA.
authors: Naval P
authors: NP
authors: Shanware
authors: Lihong
authors: L
authors: Zhan
authors: John A
authors: JA
authors: Hutchinson
authors: Sang Hwa
authors: SH
authors: Kim
authors: Leah M
authors: LM
authors: Williams
authors: Randal S
authors: RS
authors: Tibbetts
mesh_terms: D051697:Activating Transcription Factor 1 / Q000737:chemistry / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D064007:Ataxia Telangiectasia Mutated Proteins; D050882:CREB-Binding Protein / Q000737:chemistry / Q000378:metabolism; D047389:Casein Kinase I / Q000378:metabolism; D047390:Casein Kinase II / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D049109:Cell Proliferation; D017124:Conserved Sequence; D017077:Culture Media, Conditioned / Q000494:pharmacology; D017362:Cyclic AMP Response Element-Binding Protein / Q000737:chemistry / Q000378:metabolism*; D004249:DNA Damage; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D019143:Evolution, Molecular; D015971:Gene Expression Regulation, Enzymologic; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D010766:Phosphorylation / Q000187:drug effects / Q000528:radiation effects; D054648:Protein Phosphatase 2 / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012694:Serine / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D051697:Activating Transcription Factor 1; D018797:Cell Cycle Proteins; D017077:Culture Media, Conditioned; D017362:Cyclic AMP Response Element-Binding Protein; D004268:DNA-Binding Proteins; D012333:RNA, Messenger; D025521:Tumor Suppressor Proteins; D012694:Serine; 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; D017346:Protein Serine-Threonine Kinases; D054648:Protein Phosphatase 2