A nucleosomal function for IkappaB kinase-alpha in NF-kappaB-dependent gene expression.
NF-kappaB is a principal transcriptional regulator of diverse cytokine-mediated processes and is tightly controlled by the IkappaB kinase complex (IKK-alpha/beta/gamma). IKK-beta and IKK-gamma are critical for cytokine-induced NF-kappaB function, whereas IKK-alpha is thought to be involved in other regulatory pathways. However, recent data suggest a role for IKK-alpha in NF-kappaB-dependent gene expression in response to cytokine treatment. Here we demonstrate nuclear accumulation of IKK-alpha after cytokine exposure, suggesting a nuclear function for this protein. Consistent with this, chromatin immunoprecipitation (ChIP) assays reveal that IKK-alpha was recruited to the promoter regions of NF-kappaB-regulated genes on stimulation with tumour-necrosis factor-alpha. Notably, NF-kappaB-regulated gene expression is suppressed by the loss of IKK-alpha and this correlates with a complete loss of gene-specific phosphorylation of histone H3 on serine 10, a modification previously associated with positive gene expression. Furthermore, we show that IKK-alpha can directly phosphorylate histone H3 in vitro, suggesting a new substrate for this kinase. We propose that IKK-alpha is an essential regulator of NF-kappaB-dependent gene expression through control of promoter-associated histone phosphorylation after cytokine exposure. These findings provide additional insight into the role of the IKK complex in NF-kappaB-regulated gene expression.
Anest
Vasiliki
V
Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599, USA.
Hanson
Julie L
JL
Cogswell
Patricia C
PC
Steinbrecher
Kris A
KA
Strahl
Brian D
BD
Baldwin
Albert S
AS
D000818:Animals; D005347:Fibroblasts; D017353:Gene Deletion; D005786:Gene Expression Regulation / Q000187:drug effects; D006657:Histones / Q000378:metabolism; D051550:I-kappa B Kinase; D020672:I-kappa B Proteins / Q000235:genetics; D015850:Interleukin-6 / Q000235:genetics; D051379:Mice; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009707:Nucleosomes / Q000187:drug effects / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D011401:Promoter Regions, Genetic / Q000235:genetics; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D006657:Histones; D020672:I-kappa B Proteins; D015850:Interleukin-6; D016328:NF-kappa B; C000606205:Nfkbia protein, mouse; D009707:Nucleosomes; D012333:RNA, Messenger; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha; D000072000:NF-KappaB Inhibitor alpha; D017346:Protein Serine-Threonine Kinases; C496564:Chuk protein, mouse; D051550:I-kappa B Kinase; C496562:Ikbkb protein, mouse; C496566:Ikbke protein, mouse