title: Direct regulation of CREB transcriptional activity by ATM in response to genotoxic stress.
abstract: Ataxia-telangiectasia (A-T) is a syndrome of cancer susceptibility, immune dysfunction, and neurodegeneration that is caused by mutations in the A-T-mutated (ATM) gene. ATM has been implicated as a critical regulator of cellular responses to DNA damage, including the activation of cell cycle checkpoints and induction of apoptosis. Although defective cell cycle-checkpoint regulation and associated genomic instability presumably contribute to cancer susceptibility in A-T, the mechanism of neurodegeneration in A-T is not well understood. In addition, although ATM is required for the induction of the p53 transcriptional program in response to DNA damage, the identities of the relevant transcription factors that mediate ATM-dependent changes in gene expression remain largely undetermined. In this article, we describe a signal transduction pathway linking ATM directly to the Ca(2+)/cAMP response element-binding protein, CREB, a transcription factor that regulates cell growth, homeostasis, and survival. ATM phosphorylated CREB in vitro and in vivo in response to ionizing radiation (IR) and H(2)O(2) on a stress-inducible domain. IR-induced phosphorylation of CREB correlated with a decrease in CREB transactivation potential and reduced interaction between CREB and its transcriptional coactivator, CREB-binding protein (CBP). A CREB mutant containing Ala substitutions at ATM phosphorylation sites displayed enhanced transactivation potential, resistance to inhibition by IR, and increased binding to CBP. We propose that ATM-mediated phosphorylation of CREB in response to DNA damage modulates CREB-dependent gene expression and that dysregulation of the ATM-CREB pathway may contribute to neurodegeneration in A-T.
authors.affiliation: Molecular and Cellular Pharmacology Program, Department of Pharmacology, University of Wisconsin, Madison, WI 53706, USA.
authors.forename: Yuling
authors.initials: Y
authors.lastname: Shi
authors.forename: Sujatha L
authors.initials: SL
authors.lastname: Venkataraman
authors.forename: Gerald E
authors.initials: GE
authors.lastname: Dodson
authors.forename: Angela M
authors.initials: AM
authors.lastname: Mabb
authors.forename: Scott
authors.initials: S
authors.lastname: LeBlanc
authors.forename: Randal S
authors.initials: RS
authors.lastname: Tibbetts
mesh_terms: D000595:Amino Acid Sequence; D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins; D002460:Cell Line; D017362:Cyclic AMP Response Element-Binding Protein / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D004268:DNA-Binding Proteins; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007259:Infrared Rays; D008969:Molecular Sequence Data; D009153:Mutagens / Q000494:pharmacology*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000502:physiology*; D014158:Transcription, Genetic / Q000502:physiology*; D025521:Tumor Suppressor Proteins
chemical_list: D018797:Cell Cycle Proteins; D017362:Cyclic AMP Response Element-Binding Protein; D004268:DNA-Binding Proteins; D009153:Mutagens; D025521:Tumor Suppressor Proteins; D006861:Hydrogen Peroxide; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases