Cyclin-dependent kinase 6 phosphorylates NF-κB P65 at serine 536 and contributes to the regulation of inflammatory gene expression

PLoS One. 2012;7(12):e51847. doi: 10.1371/journal.pone.0051847. Epub 2012 Dec 26.

Abstract

Nuclear factor kappa-B (NF-κB) activates multiple genes with overlapping roles in cell proliferation, inflammation and cancer. Using an unbiased approach we identified human CDK6 as a novel kinase phosphorylating NF-κB p65 at serine 536. Purified and reconstituted CDK6/cyclin complexes phosphorylated p65 in vitro and in transfected cells. The physiological role of CDK6 for basal as well as cytokine-induced p65 phosphorylation or NF-κB activation was revealed upon RNAi-mediated suppression of CDK6. Inhibition of CDK6 catalytic activity by PD332991 suppressed activation of NF-κB and TNF-induced gene expression. In complex with a constitutively active viral cyclin CDK6 stimulated NF-κB p65-mediated transcription in a target gene specific manner and this effect was partially dependent on its ability to phosphorylate p65 at serine 536. Tumor formation in thymi and spleens of v-cyclin transgenic mice correlated with increased levels of p65 Ser536 phosphorylation, increased expression of CDK6 and upregulaton of the NF-κB target cyclin D3. These results suggest that aberrant CDK6 expression or activation that is frequently observed in human tumors can contribute through NF-κB to chronic inflammation and neoplasia.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis
  • Cell Nucleus / genetics
  • Cell Nucleus / metabolism
  • Cell Proliferation
  • Cyclin-Dependent Kinase 6 / antagonists & inhibitors
  • Cyclin-Dependent Kinase 6 / genetics
  • Cyclin-Dependent Kinase 6 / metabolism*
  • Gene Expression Regulation, Neoplastic*
  • HeLa Cells
  • Humans
  • I-kappa B Proteins / metabolism
  • Immunoblotting
  • Inflammation / genetics*
  • Inflammation / metabolism
  • Inflammation / pathology
  • Lymphocytes / metabolism
  • Lymphocytes / pathology
  • Mice
  • Mice, Transgenic
  • NF-kappa B / genetics
  • NF-kappa B / metabolism*
  • Phosphorylation
  • RNA, Small Interfering / genetics
  • Serine / chemistry
  • Serine / genetics
  • Serine / metabolism*
  • Splenic Neoplasms / genetics*
  • Splenic Neoplasms / metabolism
  • Splenic Neoplasms / pathology
  • Tandem Mass Spectrometry
  • Thymus Neoplasms / genetics*
  • Thymus Neoplasms / metabolism
  • Thymus Neoplasms / pathology
  • Tumor Necrosis Factor-alpha / pharmacology

Substances

  • I-kappa B Proteins
  • NF-kappa B
  • RNA, Small Interfering
  • Tumor Necrosis Factor-alpha
  • Serine
  • Cyclin-Dependent Kinase 6

Grant support

This work was supported by grants from the Deutsche Forschungsgemeinschaft Kr1143/7-1, TRR81 (B2), Na292/9-1, SFB854 (TP4). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.