title: D4476, a cell-permeant inhibitor of CK1, suppresses the site-specific phosphorylation and nuclear exclusion of FOXO1a.
abstract: The protein kinase CK1 phosphorylates serine residues that are located close to another phosphoserine in the consensus pSer-Xaa-Xaa-Ser. This specificity generates regions in its target proteins containing two or more neighbouring phosphoserine residues, termed here multisite phosphorylation domains (MPDs). In this paper, we demonstrate that D4476 is a potent and rather selective inhibitor of CK1 in vitro and in cells. In H4IIE hepatoma cells, D4476 specifically inhibits the phosphorylation of endogenous forkhead box transcription factor O1a (FOXO1a) on Ser322 and Ser325 within its MPD, without affecting the phosphorylation of other sites. Our results indicate that these residues are targeted by CK1 in vivo and that the CK1-mediated phosphorylation of the MPD is required for accelerated nuclear exclusion of FOXO1a in response to IGF-1 and insulin. D4476 is much more potent and specific than IC261 or CKI-7, and is therefore the most useful CK1 inhibitor currently available for identifying physiological substrates of CK1.
authors.affiliation: MRC Protein Phosphorylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK. g.rena@dundee.ac.uk
authors.forename: Graham
authors.initials: G
authors.lastname: Rena
authors.forename: Jenny
authors.initials: J
authors.lastname: Bain
authors.forename: Matthew
authors.initials: M
authors.lastname: Elliott
authors.forename: Philip
authors.initials: P
authors.lastname: Cohen
mesh_terms: D001549:Benzamides / Q000378:metabolism / Q000494:pharmacology*; D047389:Casein Kinase I / Q000378:metabolism*; D002478:Cells, Cultured; D016895:Culture Media, Serum-Free; D004268:DNA-Binding Proteins / Q000378:metabolism*; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors; D006801:Humans; D007093:Imidazoles / Q000378:metabolism / Q000494:pharmacology*; D047468:Immunoprecipitation; D010766:Phosphorylation; D012694:Serine / Q000737:chemistry; D013379:Substrate Specificity; D014157:Transcription Factors / Q000378:metabolism*; D014407:Tumor Cells, Cultured
chemical_list: C493177:4-(4-(2,3-dihydrobenzo(1,4)dioxin-6-yl)-5-pyridin-2-yl-1H-imidazol-2-yl)benzamide; D001549:Benzamides; D016895:Culture Media, Serum-Free; D004268:DNA-Binding Proteins; C085126:FOXO1 protein, human; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors; D007093:Imidazoles; D014157:Transcription Factors; D012694:Serine; D047389:Casein Kinase I