Dataset Information

Disruption of IkappaB kinase (IKK)-mediated RelA serine 536 phosphorylation sensitizes human multiple myeloma cells to histone deacetylase (HDAC) inhibitors.

ABSTRACT: Post-translational modifications of RelA play an important role in regulation of NF-?B activation. We previously demonstrated that in malignant hematopoietic cells, histone deacetylase inhibitors (HDACIs) induced RelA hyperacetylation and NF-?B activation, attenuating lethality. We now present evidence that I?B kinase (IKK) ?-mediated RelA Ser-536 phosphorylation plays a significant functional role in promoting RelA acetylation, inducing NF-?B activation, and limiting HDACI lethality in human multiple myeloma (MM) cells. Immunoblot profiling revealed that although basal RelA phosphorylation varied in MM cells, Ser-536 phosphorylation correlated with IKK activity. Exposure to the pan-HDACIs vorinostat or LBH-589 induced phosphorylation of IKK?/? (Ser-180/Ser-181) and RelA (Ser-536) in MM cells, including cells expressing an I?B? "super-repressor," accompanied by increased RelA nuclear translocation, acetylation, DNA binding, and transactivation activity. These events were substantially blocked by either pan-IKK or IKK?-selective inhibitors, resulting in marked apoptosis. Consistent with these events, inhibitory peptides targeting either the NF-?B essential modulator (NEMO) binding domain for IKK complex formation or RelA phosphorylation sites also significantly increased HDACI lethality. Moreover, IKK? knockdown by shRNA prevented Ser-536 phosphorylation and significantly enhanced HDACI susceptibility. Finally, introduction of a nonphosphorylatable RelA mutant S536A, which failed to undergo acetylation in response to HDACIs, impaired NF-?B activation and increased cell death. These findings indicate that HDACIs induce Ser-536 phosphorylation of the NF-?B subunit RelA through an IKK?-dependent mechanism, an action that is functionally involved in activation of the cytoprotective NF-?B signaling cascade primarily through facilitation of RelA acetylation rather than nuclear translocation.

SUBMITTER: Dai Y

PROVIDER: S-EPMC3190767 | biostudies-literature | 2011 Sep

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Disruption of IkappaB kinase (IKK)-mediated RelA serine 536 phosphorylation sensitizes human multiple myeloma cells to histone deacetylase (HDAC) inhibitors.

Dai Yun Y Chen Shuang S Wang Li L Pei Xin-Yan XY Funk Vanessa L VL Kramer Lora B LB Dent Paul P Grant Steven S

The Journal of biological chemistry 20110804 39

Post-translational modifications of RelA play an important role in regulation of NF-κB activation. We previously demonstrated that in malignant hematopoietic cells, histone deacetylase inhibitors (HDACIs) induced RelA hyperacetylation and NF-κB activation, attenuating lethality. We now present evidence that IκB kinase (IKK) β-mediated RelA Ser-536 phosphorylation plays a significant functional role in promoting RelA acetylation, inducing NF-κB activation, and limiting HDACI lethality in human mu ...[more]

PMID: 21816815

Similar Datasets

Project description:ObjectiveKlotho is an antiaging hormone present in the kidney that extends the lifespan, regulates kidney function, and modulates cellular responses to oxidative stress. We investigated whether Klotho levels and signaling modulate inflammation in diabetic kidneys.Research design and methodsRenal Klotho expression was determined by quantitative real-time PCR and immunoblot analysis. Primary mouse tubular epithelial cells were treated with methylglyoxalated albumin, and Klotho expression and inflammatory cytokines were measured. Nuclear factor (NF)-?B activation was assessed by treating human embryonic kidney (HEK) 293 and HK-2 cells with tumor necrosis factor (TNF)-? in the presence or absence of Klotho, followed by immunoblot analysis to evaluate inhibitor of ?B (I?B)? degradation, I?B kinase (IKK) and p38 activation, RelA nuclear translocation, and phosphorylation. A chromatin immunoprecipitation assay was performed to analyze the effects of Klotho signaling on interleukin-8 and monocyte chemoattractant protein-1 promoter recruitment of RelA and RelA serine (Ser)(536).ResultsRenal Klotho mRNA and protein were significantly decreased in db/db mice, and a similar decline was observed in the primary cultures of mouse tubule epithelial cells treated with methylglyoxal-modified albumin. The exogenous addition of soluble Klotho or overexpression of membranous Klotho in tissue culture suppressed NF-?B activation and subsequent production of inflammatory cytokines in response to TNF-? stimulation. Klotho specifically inhibited RelA Ser(536) phosphorylation as well as promoter DNA binding of this phosphorylated form of RelA without affecting IKK-mediated I?B? degradation, total RelA nuclear translocation, and total RelA DNA binding.ConclusionsThese findings suggest that Klotho serves as an anti-inflammatory modulator, negatively regulating the production of NF-?B-linked inflammatory proteins via a mechanism that involves phosphorylation of Ser(536) in the transactivation domain of RelA.

Dataset Information

Disruption of IkappaB kinase (IKK)-mediated RelA serine 536 phosphorylation sensitizes human multiple myeloma cells to histone deacetylase (HDAC) inhibitors.

Publications

Disruption of IkappaB kinase (IKK)-mediated RelA serine 536 phosphorylation sensitizes human multiple myeloma cells to histone deacetylase (HDAC) inhibitors.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets