Specification of the NF-kappaB transcriptional response by p65 phosphorylation and TNF-induced nuclear translocation of IKK epsilon.

ABSTRACT: Here we investigated the regulation of NF-?B activity by post-translational modifications upon reconstitution of NF-?B p65-deficient cells with the wild-type protein or phosphorylation-defect mutants. Analysis of NF-?B 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-?B 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 IKK? to the nucleus and also to promyelocytic leukemia (PML) nuclear bodies. This inducible IKK? translocation was dependent on p65 phosphorylation and was prevented by the oncogenic PML-RAR? fusion protein. Chromatin immunoprecipitation experiments revealed the inducible association of IKK? to the control regions of several NF-?B target genes. In the nucleus, the kinase contributes to the expression of a subset of NF-?B-regulated genes, thus revealing a novel role of IKK? for the control of nuclear NF-?B activity.

SUBMITTER: Moreno R 

PROVIDER: S-EPMC2952868 | biostudies-other | 2010 Oct

REPOSITORIES: biostudies-other