Oxidation of Ikappa Balpha at methionine 45 is one cause of taurine chloramine-induced inhibition of NF-kappa B activation.
A band shift of IkappaBalpha was observed in Western blots with Jurkat cells treated with 1 mm taurine chloramine (TauCl) for 1 h. TauCl treatment inhibited tumor necrosis factor alpha (TNFalpha)-initiated nuclear factor kappaB (NF-kappaB) activation. TauCl did not inhibit either the upstream of IkappaB kinase (IKK) activation or IKK itself but did inhibit NF-kappaB activation induced by IKK overexpression. Deletion experiments showed that a TauCl modification site causing the band shift of IkappaBalpha is Met45. High performance liquid chromatography and mass spectrometry analyses of a small peptide containing Met45 revealed that TauCl oxidizes Met45. A mutant of IkappaBalpha whose Met45 was converted to alanine did not generate a band shift upon TauCl treatment and degraded in response to TNFalpha stimulation. However, a reporter assay revealed that NF-kappaB-dependent luciferase expression was not fully recovered in cells transfected with this mutant. These results indicate that Met45 oxidation of IkappaBalpha is a molecular mechanism underlying the TauCl-induced inhibition of NF-kappaB activation. A similar band shift was observed when HL-60 cells expressing myeloperoxidase were treated with 100 microm hydrogen peroxide for 5 min. When rat neutrophils were incubated with bacteria, intracellular taurine decreased interleukin-8 production. Therefore, taurine may help suppress excessive inflammatory reaction in neutrophils.
Kanayama
Atsuhiro
A
Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo, Tokyo 113-8657, Japan.
Inoue
Jun-Ichiro
J
Sugita-Konishi
Yoshioko
Y
Shimizu
Makoto
M
Miyamoto
Yusei
Y
D019943:Amino Acid Substitution; D002460:Cell Line; D002851:Chromatography, High Pressure Liquid; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D017930:Genes, Reporter; D006801:Humans; D020672:I-kappa B Proteins; D016209:Interleukin-8 / Q000378:metabolism; D019169:Jurkat Cells; D007700:Kinetics; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D013058:Mass Spectrometry; D008715:Methionine; D016297:Mutagenesis, Site-Directed; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015345:Oligonucleotide Probes; D010084:Oxidation-Reduction; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D013654:Taurine / Q000031:analogs & derivatives / Q000494:pharmacology*
D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D020672:I-kappa B Proteins; D016209:Interleukin-8; D016328:NF-kappa B; C000606204:NFKBIA protein, human; C000606206:Nfkbia protein, rat; D015345:Oligonucleotide Probes; D011994:Recombinant Proteins; D000072000:NF-KappaB Inhibitor alpha; D013654:Taurine; C043410:N-chlorotaurine; D008715:Methionine; D008156:Luciferases