Specification of the NF-kappaB transcriptional response by p65 phosphorylation and TNF-induced nuclear translocation of IKK epsilon.
Here we investigated the regulation of NF-κB activity by post-translational modifications upon reconstitution of NF-κB p65-deficient cells with the wild-type protein or phosphorylation-defect mutants. Analysis of NF-κB target gene expression showed that p65 phosphorylations alone or in combination function to direct transcription in a highly target gene-specific fashion, a finding discussed here as the NF-κB barcode hypothesis. High-resolution microscopy and surface rendering revealed serine 536 phosphorylated p65 predominantly in the cytosol, while serine 468 phosphorylated p65 mainly localized in nuclear speckles. TNF stimulation resulted in the translocation of the cytosolic p65 kinase IKKε to the nucleus and also to promyelocytic leukemia (PML) nuclear bodies. This inducible IKKε translocation was dependent on p65 phosphorylation and was prevented by the oncogenic PML-RARα fusion protein. Chromatin immunoprecipitation experiments revealed the inducible association of IKKε to the control regions of several NF-κB target genes. In the nucleus, the kinase contributes to the expression of a subset of NF-κB-regulated genes, thus revealing a novel role of IKKε for the control of nuclear NF-κB activity.
Moreno
Rita
R
Institute of Biochemistry, Medical Faculty, Friedrichstrasse 24, Justus-Liebig-University, 35392 Giessen, Germany.
Sobotzik
Jürgen-Markus
JM
Schultz
Christian
C
Schmitz
M Lienhard
ML
D021581:Active Transport, Cell Nucleus / Q000187:drug effects; D000818:Animals; D002467:Cell Nucleus / Q000201:enzymology* / Q000235:genetics; D002478:Cells, Cultured; D002843:Chromatin / Q000201:enzymology; D005786:Gene Expression Regulation; D006367:HeLa Cells; D006801:Humans; D051550:I-kappa B Kinase / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D009154:Mutation; D010766:Phosphorylation; D051996:Transcription Factor RelA / Q000032:analysis / Q000378:metabolism*; D014158:Transcription, Genetic; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D002843:Chromatin; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha; D051550:I-kappa B Kinase