Pleiotropic Potential of Dehydroxymethylepoxyquinomicin for NF-κB Suppression via Reactive Oxygen Species and Unfolded Protein Response

Nakajima, Shotaro; Kato, Hironori; Gu, Liya; Takahashi, Shuhei; Johno, Hisashi; Umezawa, Kazuo; Kitamura, Masanori

doi:10.4049/jimmunol.1300155

Cited by 11 publications

(6 citation statements)

References 82 publications

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“…15) cDNAs for monocyte chemoattractant protein 1 (MCP-1) 16) were used to prepare radio-labeled probes. The expression of glyceraldehyde 3-phosphate dehydrogenase (GAPDH) was used as a loading control.…”

Section: Methodsmentioning

confidence: 99%

“…15) Briefly, cells were lysed in Radio-Immunoprecipitation Assay (RIPA) buffer (25 mM TrisHCl [pH 7.5], 150 mM sodium chloride (NaCl), 1% Triton-X, 1% sodium dodecyl sulfate (SDS), 50 mM sodium fluoride (NaF), 20 mM N-ethylmaleimide and 1 mM sodium orthovanadate (Na 3 VO 4 )) with protease inhibitor cocktail (Nacalai Tesque, Kyoto, Japan), and cell lysates were then mixed with sample buffer containing dithiothreitol and bromophenol blue.…”

Section: Methodsmentioning

confidence: 99%

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eIF2α-Independent Inhibition of TNF-α-Triggered NF-κB Activation by Salubrinal

Nakajima

Chi

Gao

et al. 2015

Biological & Pharmaceutical Bulletin

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Salubrinal is a selective inhibitor of cellular complexes that dephosphorylate eukaryotic translation initiation factor 2α (eIF2α). In previous reports, salubrinal was shown to have the potential to inhibit the activation of nuclear factor-κB (NF-κB) by several stimuli. However, the effects of salubrinal on NF-κB signaling are largely unknown. In this study, we investigated whether and how salubrinal affects NF-κB activation induced by tumor necrosis factor (TNF)-α and interleukin (IL)-1β. We found that salubrinal selectively blocked TNF-α-but not IL-1β-induced activation of NF-κB. This inhibitory effect occurred upstream of transforming growth factor (TGF)-β-activated kinase 1 (TAK1). Further experiments revealed that salubrinal blocked TNF-α-triggered NF-κB activation independent of its action on eIF2α because knockdown of eIF2α by small interfering RNA (siRNA) did not reverse the inhibitory effect of salubrinal on NF-κB. Moreover, guanabenz, a selective inhibitor of the regulatory subunit of protein phosphatase (PP) 1, also preferentially inhibited TNF-α-triggered activation of NF-κB. These findings raise the possibility that salubrinal may selectively block TNF-α-triggered activation of the NF-κB pathway through inhibition of the PP1 complex.Key words salubrinal; nuclear factor-κB; eukaryotic translation initiation factor 2α; protein phosphatase (PP) 1; guanabenz Salubrinal is a small molecule that inhibits the dephosphorylation of eukaryotic translation initiation factor 2α (eIF2α) through the suppression of protein phosphatase (PP) 1 catalytic subunits, resulting in sustained phosphorylation of eIF2α on Ser51. Through this effect, salubrinal protects cells from endoplasmic reticulum (ER) stress-mediated apoptosis.1) It has been shown that salubrinal influences several signaling pathways involved in apoptosis, autophagy and bone homeostasis.2-4) The nuclear factor-κB (NF-κB) pathway is also a target of salubrinal. Recently, Huang et al. reported that salubrinal protected against β-amyloid-triggered neuronal cell death and microglial activation through the suppression of NF-κB activation. 5) Moreover, Hamamura et al. suggested that salubrinal reduced the inflammatory cytokine-driven expression of matrix metalloproteinase 13 via blockade of the p38 mitogen-activated protein kinase pathway and the NF-κB pathway.6) Currently, however, the mechanism by which salubrinal regulates NF-κB remains largely unknown.The Rel/NF-κB family consists of five different members, namely, p50, p52, p65 (RelA), RelB and c-Rel, and functions as a transcription factor through the formation of homo-or heterodimers.7) NF-κB plays crucial roles in the regulation of inflammation, immune responses and apoptosis. 8) In unstimulated cells, NF-κB is retained in the cytoplasm through binding to inhibitors of NF-κB (IκBs). However, in response to several stimuli such as inflammatory cytokines, oxidative stress, ultraviolet light and bacterial components, IκB kinase (IKK) complex including IKKα, IKKβ and IKKγ (also called NF-κB essential modu...

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

eIF2α-Independent Inhibition of TNF-α-Triggered NF-κB Activation by Salubrinal

Nakajima

Chi

Gao

et al. 2015

Biological & Pharmaceutical Bulletin

Self Cite

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“…In human renal tubular cells (HK-2), ER stress increases oxidative stress and reduces anti-oxidant enzymes by reducing micro-RNA (miR)-205 expression [91]. Likewise in rat renal tubular cells (NRK-52E) Dehydroxymethylepoxyquinomicin (DHMEQ, an NF-κB inhibitor), increases ROS, which rapidly induce all three arms of the UPR [92]. Thus ROS activate the UPR [82,92] and depending on the cellular context and conditions the UPR can either negatively [90] or positively regulate generation of ROS [91].…”

Section: Renal Cell Systemsmentioning

confidence: 99%

Endoplasmic Reticulum Stress in the Diabetic Kidney, the Good, the Bad and the Ugly

Cunard

2015

JCM

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Diabetic kidney disease is the leading worldwide cause of end stage kidney disease and a growing public health challenge. The diabetic kidney is exposed to many environmental stressors and each cell type has developed intricate signaling systems designed to restore optimal cellular function. The unfolded protein response (UPR) is a homeostatic pathway that regulates endoplasmic reticulum (ER) membrane structure and secretory function. Studies suggest that the UPR is activated in the diabetic kidney to restore normal ER function and viability. However, when the cell is continuously stressed in an environment that lies outside of its normal physiological range, then the UPR is known as the ER stress response. The UPR reduces protein synthesis, augments the ER folding capacity and downregulates mRNA expression of genes by multiple pathways. Aberrant activation of ER stress can also induce inflammation and cellular apoptosis, and modify signaling of protective processes such as autophagy and mTORC activation. The following review will discuss our current understanding of ER stress in the diabetic kidney and explore novel means of modulating ER stress and its interacting signaling cascades with the overall goal of identifying therapeutic strategies that will improve outcomes in diabetic nephropathy.

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“…Another explanation is based on the duration of ROS production. Accordingly, sustained ROS generation can inhibit NF-κB activity even though ROS can activate NF-κB initially [42].…”

Section: Discussionmentioning

confidence: 99%

Differential oxidative and pro-apoptotic response of cancer and normal cells to an anti-inflammatory agent CLEFMA

Awasthi

Sahoo

2021

Preprint

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Selective killing of cancer cells by chemotherapy has been an age old challenge, but certain unique features of cancer cells allow discriminatory response between cancer and normal cells. The objectives of this study was to investigate pro-oxidant and apoptotic effects of CLEFMA, an anti-inflammatory compound with anticancer activity, in lung cancer cells versus normal lung fibroblasts and to establish its maximum tolerated dose (MTD) in mice. We found that CLEFMA preferentially induced reactive oxygen species (ROS)-mediated apoptosis in H441, H1650 and H226 cancer cells, but spared normal CCL151 and MRC9 fibroblasts. Immunoblotting studies revealed that CLEFMA-induced apoptosis is associated with p53 phosphorylation in cancer cells which was not observed in CLEFMA treated normal fibroblasts. CLEFMA showed no effect on NF-κB p-65 expression in the normal lung fibroblasts, whereas its translocation to nucleus was inhibited in cancer cells. Furthermore, CLEFMA treatment also inhibited the DNA-binding activity of NF-κB p65 in H441cancer cells, but not in normal CCL151 cells. Preclinical toxicology studies in CD31 mice showed that CLEFMA was not toxic when injected daily for 7 days or injected weekly for 4 weeks. Based on survival data, MTD of CLEFMA was estimated as 30 mg/kg bodyweight. We conclude that CLEFMA exploits the biochemical differences in cancer and normal cells and selectively induces ROS in cancer cells. Secondly, CLEFMA can be safely administered in vivo because its known dose necessary for in vivo efficacy as anti-inflammatory and anti-tumor agent (0.4 mg/kg) is 75 times lower than its MTD.

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Pleiotropic Potential of Dehydroxymethylepoxyquinomicin for NF-κB Suppression via Reactive Oxygen Species and Unfolded Protein Response

Cited by 11 publications

References 82 publications

eIF2α-Independent Inhibition of TNF-α-Triggered NF-κB Activation by Salubrinal

eIF2α-Independent Inhibition of TNF-α-Triggered NF-κB Activation by Salubrinal

Endoplasmic Reticulum Stress in the Diabetic Kidney, the Good, the Bad and the Ugly

Differential oxidative and pro-apoptotic response of cancer and normal cells to an anti-inflammatory agent CLEFMA

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