title: Phosphorylation of p105 PEST sequence via a redox-insensitive pathway up-regulates processing of p50 NF-kappaB.
abstract: The p105 Rel protein has dual functions; it is the precursor of the p5O subunit of NF-kappaB, and it acts as an IkappaB-like inhibitor to retain other Rel subunits in the cytoplasm. We have investigated the posttranslational regulation of p105 following activation of Jurkat T cells and find that a rapid and sustained phosphorylation of p105 is induced. The inducible phosphorylation occurs on multiple serines in the C-terminal-most 150 amino acids of the molecule, a region rich in Pro, Glu, Ser, and Thr residues. Phosphorylation of p105 in Jurkat cells treated with phorbol 12-myristate 13-acetate/ionomycin or with okadaic acid, another activator of NF-kappaB, is correlated with an increase in proteolytic processing to p5O. Intact PEST sequences are required for the phorbol 12-myristate 13-acetate/ionomycin-induced p105 processing, as a 68-amino acid C-terminal deletion abolishes the response to stimulation. When compounds that block Ikappa B alpha phosphorylation and degradation were tested, the serine protease inhibitors L-1-tosylamido-2-phenylethyl chloromethyl ketone and 1-chloro-3-tosyl-amido-7-amino-2-heptanone blocked inducible p105 phosphorylation, but the antioxidants pyrrolidine dithiocarbamate and butylated hydroxyanisol did not. Thus, while regulation of the p105 IkappaB resembles that of lkappaBa, involving inducible serine phosphorylation and proteolysis of the inhibitory ankyrin repeat domain, it depends on a different, redox-insensitive, signaling pathway.
authors.affiliation: Unité de Biologie Moléculaire de l'Expression Génique, Institut Pasteur, Paris, France.
authors.forename: M L
authors.initials: ML
authors.lastname: MacKichan
authors.forename: F
authors.initials: F
authors.lastname: Logeat
authors.forename: A
authors.initials: A
authors.lastname: Israël
mesh_terms: D000595:Amino Acid Sequence; D000975:Antioxidants / Q000494:pharmacology; D002460:Cell Line; D004988:Ethers, Cyclic / Q000494:pharmacology; D006801:Humans; D015759:Ionomycin / Q000494:pharmacology; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D052002:NF-kappa B p50 Subunit; D019319:Okadaic Acid; D010084:Oxidation-Reduction; D010766:Phosphorylation; D011498:Protein Precursors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D011518:Proto-Oncogene Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020569:Proto-Oncogene Proteins c-rel; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology; D015398:Signal Transduction; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D015854:Up-Regulation
chemical_list: D000975:Antioxidants; D004988:Ethers, Cyclic; D016328:NF-kappa B; D052002:NF-kappa B p50 Subunit; D011498:Protein Precursors; D011518:Proto-Oncogene Proteins; D020569:Proto-Oncogene Proteins c-rel; D015842:Serine Proteinase Inhibitors; C093394:TONSL protein, human; D019319:Okadaic Acid; D015759:Ionomycin; D013755:Tetradecanoylphorbol Acetate