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D4476, a cell‐permeant inhibitor of CK1, suppresses the site‐specific phosphorylation and nuclear exclusion of FOXO1a
Author(s) -
Rena Graham,
Bain Jenny,
Elliott Matthew,
Cohen Philip
Publication year - 2004
Publication title -
embo reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.584
H-Index - 184
eISSN - 1469-3178
pISSN - 1469-221X
DOI - 10.1038/sj.embor.7400048
Subject(s) - phosphoserine , phosphorylation , casein kinase 1 , serine , chemistry , in vitro , nuclear transport , kinase , microbiology and biotechnology , protein phosphorylation , biochemistry , protein kinase a , biology , cell nucleus , cytoplasm
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.