Sedanolide ameliorates hydrogen peroxide-induced apoptotic cell death via activation of KEAP1-NRF2 pathway
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PROVIDER: PRJNA1028497 | ENA |
REPOSITORIES: ENA
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Project description:Sedanolide is a bioactive compound with anti-inflammatory and antitumor activities. Although it has been recently suggested that sedanolide activates the nuclear factor E2-related factor 2 (NRF2) pathway, there is little research on its effects on cellular resistance to oxidative stress. The objective of the present study was to investigate the function of sedanolide in suppressing hydrogen peroxide (H2O2)-induced oxidative damage and the underlying molecular mechanisms in human hepatoblastoma cell line HepG2 cells. We found that sedanolide activated the antioxidant response element (ARE)-dependent transcription mediated by the nuclear translocation of NRF2. Pathway enrichment analysis of RNA sequencing data revealed that sedanolide upregulated the transcription of antioxidant enzymes involved in the NRF2 pathway and glutathione metabolism. Then, we further investigated whether sedanolide exerts cytoprotective effects against H2O2-induced cell death. We showed that sedanolide significantly attenuated cytosolic and mitochondrial reactive oxygen species (ROS) generation induced by exposure to H2O2. Furthermore, we demonstrated that pretreatment with sedanolide conferred a significant cytoprotective effect against H2O2-induced cell death by preventing the decrease of the mitochondrial membrane potential and the increase of caspase-3/7 activity. Our study demonstrated that sedanolide enhanced cellular resistance to oxidative damage via the activation of the Keich-like ECH-associated protein 1 (KEAP1)–NRF2 pathway.
2023-11-29 | GSE245428 | GEO
Project description:Keap1 overexpressed and Nrf2 depleted CL1-5 cells were used to identify genes regulated by Keap1/Nrf2 axis-dependent gene regulations We used microarrays to detail the global programme of gene expression underlying metastasis and identified distinct classes of Keap1/Nrf2-regulated genes during this process. CL1-5 cells stably expressed Keap1 expressing construct and Nrf2-specific shRNA were analyzed compared to control cells
2015-03-04 | E-GEOD-66473 | biostudies-arrayexpress
Project description:Nrf2 is a transcription factor playing an essential role in stress response. A knowledge of the significance of Nrf2 in cell function has not, as yet, reached out beyond transactivation of gene expression. This paper shows that GDF-15 and SDF-1-induced angiogenesis strongly depends on Nrf2 presence, but is not related to its transcriptional activity. We propose, that Nrf2 serves as a protein restraining Keap1, its known transcriptional repressor. Deficiency of Nrf2 protein available for Keap1 leads to overabundance of RhoGAP1, the protein regulating Cdc42 activity, and impairs podosome assembly, thereby indisposing actin rearrangements, preventing migration and angiogenesis. These activities can be rescued by concomitant deletion of RhoGAP1 or Keap1. We suggest that a new Nrf2 function of a Keap1 scavenger implies revising the established murine model of Nrf2 deficiency as a transcriptional knock out (tKO) mouse. The N-terminal fragment of Nrf2, containing Neh2 domain binding Keap1, is present in these animals. Thus, regarding the function of Nrf2 as a protein sequestering Keap1, both published and unpublished data on Nrf2-Keap1 duet may gain new interpretation.
2018-11-28 | PXD009161 | Pride
Project description:Cancer-derived loss-of-function mutations in the KEAP1 tumor suppressor gene stabilize the NRF2 transcription factor, resulting in a pro-survival gene expression program that alters cellular metabolism and neutralizes oxidative stress. In a previous study of KEAP1 mutations observed in lung cancer, we classified 40% of the mutations as ‘superbinders’ (superbinders). These mutants bind and ubiquitylate NRF2 but do not promote NRF2 degradation. Here, we further investigated the molecular mechanism(s) driving the superbinder phenotype. BioID-based quantitative proteomic analysis of the R320Q and R470C superbinder mutations revealed increased co-complexed NRF2 without significant alteration to other KEAP1-associated proteins, including CUL3, VCP, and several ubiquitin receptors within the proteasome lid. Dynamic simulation modeling and limited proteolysis analyses suggest that superbinder mutations stabilize residues in KEAP1 that contact NRF2. In cells, KEAP1 R320Q and R470C mutants co-localize with NRF2, p62/SQSTM1 and polyubiquitin in spherical clusters that rapidly fuse and dissolve; KEAP1-NRF2 localization to these clusters requires p62. Expression of R320Q and R470C in lung cancer cells provided resistance to the reactive oxygen species-inducing drug bleomycin. We present a model wherein superbinder mutations alter the conformational dynamics of the KEAP1-NRF2 complex to alter the cycling of KEAP1 between open and closed conformations, thus inhibiting NRF2 degradation.
2018-11-07 | PXD008411 | Pride
Project description:Keap1 overexpressed and Nrf2 depleted CL1-5 cells were used to identify genes regulated by Keap1/Nrf2 axis-dependent gene regulations We used microarrays to detail the global programme of gene expression underlying metastasis and identified distinct classes of Keap1/Nrf2-regulated genes during this process.
2015-03-04 | GSE66473 | GEO
Project description:The activation of the transcription factor NF-E2-related factor 2 (Nrf2) maintains cellular homeostasis in response to oxidative stress by the regulation of multiple cytoprotective genes. Without stressors the activity of Nrf2 is inhibited by its interaction with the kelch-like ECH-associated protein 1 (Keap1). Here, we describe RA839, a small molecule that binds non-covalently to the Nrf2-interacting kelch domain of Keap1 with a Kd of approximately 6 µM, as demonstrated by X-ray co-crystallization and isothermal titration calorimetry. Whole-genome DNA arrays showed that at 10 µM RA839 significantly regulated 105 genes in bone marrow-derived macrophages. Canonical pathway mapping of these genes revealed an activation of pathways linked with Nrf2 signalling. These pathways were also activated after the activation of Nrf2 by the silencing of Keap1 expression. RA839 regulated only two genes in Nrf2 knockout macrophages. Similar to the activation of Nrf2 by either silencing of Keap1 expression or by the reactive compound CDDO-Me, RA839 prevented the induction of both inducible nitric oxide synthase expression and nitric oxide release in response to lipopolysaccharides in macrophages. In mice RA839 acutely induced Nrf2-target gene expression in liver. RA839 is a selective inhibitor of the Keap1/Nrf2 interaction and a useful tool compound to study the biology of Nrf2. Gene expression profile of bone marrow derived murine macrophages (BMDM) from Nrf2+/+ or Nrf2-/- mice treated with RA838, siKeap1-1 or siKeap1-2 were compared to untreated DMSO control or siControl. Four biological replicates were used for each sample group.
2015-10-31 | E-GEOD-71695 | biostudies-arrayexpress
Project description:Genetic versus chemoprotective activation of Nrf2 signaling: overlapping yet distinct hepatic gene expression profiles between Keap1 knockout and triterpenoid treated mice; Loss of Nrf2 signaling increases susceptibility to acute toxicity, inflammation, and carcinogenesis in mice due to the inability to mount adaptive responses. By contrast, disruption of Keap1 (a cytoplasmic modifier of Nrf2 turnover) protects against these stresses in mice; although dominant negative mutations in Keap1 have been identified recently in some human cancers. Global characterization of Nrf2 activation is important to exploit this pathway for chemoprevention in healthy, yet at-risk individuals and also to elucidate the consequences of hijacking the pathway in Keap1-mutant human cancers. This analysis also enables a global characterization of the pharmacodynamic action of CDDO-Im at a low dose that is relevant to chemoprevention. Experiment Overall Design: Liver-targeted conditional Keap1-null (CKO) mice provide a model of genetic activation of Nrf2 signaling. By coupling global gene expression analysis of CKO mice with analysis of pharmacologic activation using the synthetic oleanane triterpenoid CDDO-Im, we are able to gain insight into pathways affected by Nrf2 activation. CDDO-Im is an extremely potent activator of Nrf2 signaling. CKO mice were used to identify genes modulated by genetic activation of Nrf2 signaling. The CKO response was compared to hepatic global gene expression changes in wild-type mice treated with CDDO-Im at a maximal Nrf2 activating dose. n=3/group, male 9 week old mice were used. Mice were treated with a single dose of vehicle (10% Cremophor-EL, 10% DMSO, and PBS) or 30 umol CDDO-Im/kg body weight by gavage and sacrificed 6 h later.
2009-05-11 | E-GEOD-15633 | biostudies-arrayexpress
Project description:Clinical evidence has revealed that high-level activation of NRF2 caused by somatic mutations in NRF2 is frequently detected in esophageal squamous cell carcinoma (ESCC), whereas that by somatic mutations in KEAP1, a negative regulator of NRF2, is not. Here, we challenged to generate a mouse model of NRF2-activated ESCC using the cancer-derived NRF2L30F mutation and cancer-driver mutant Trp53R172H. Concomitant expression of NRF2L30F and Trp53R172H induced proliferation of squamous cell epithelia and resulted in NRF2-activated ESCC-like lesions. In contrast, while squamous cell-specific deletion of KEAP1 induced similar NRF2 hyper-activation, the loss-of-KEAP1 combined with Trp53R172H did not elicit the proliferation and formation of ESCC-like lesions. Instead, KEAP1-deleted cells disappeared from the esophageal epithelium over time by cell competition. These findings provide insights into the observation that somatic mutations are more frequently observed in NRF2 than in KEAP1, and the mouse model developed here will be instrumental in elucidating the mechanistic basis leading to NRF2-activated ESCC.
2024-03-22 | GSE255927 | GEO
Project description:Background & Aims: Inflammation in chronic liver diseases induces oxidative stress and thus may contribute to progression of liver injury, fibrosis, and carcinogenesis. The KEAP1/NRF2 axis is a major regulator of cellular redox balance. In the present study, we investigated whether the KEAP1/NRF2 system is involved in liver disease progression in human and mice. Methods: The clinical relevance of oxidative stress was investigated in a well-characterized cohort of NAFLD patients (n=63) by liver RNA sequencing and correlated with histological and clinical parameters. For functional analysis hepatocyte-specific NEMO knock-out (NEMO∆hepa) mice were crossed with hepatocyte-specific KEAP1 knock-out (KEAP1∆hepa) mice. Results: Immunohistochemical analysis of human liver sections showed increased oxidative stress and high NRF2 expression in patients with chronic liver disease. RNA sequencing of liver samples in a human pediatric NAFLD cohort revealed a significant increase of NRF2 activation correlating with the grade of inflammation, but not with the grade of steatosis, which could be confirmed in a second adult NASH cohort. In mice, microarray analysis revealed that KEAP1 deletion induces NRF2 target genes involved in glutathione metabolism and xenobiotic stress (e.g., Nqo1). Furthermore, deficiency of one of the most important antioxidants, glutathione (GSH), in NEMO∆hepa livers was rescued after deleting KEAP1. As a consequence, NEMO∆hepa/KEAP1∆hepa livers showed reduced apoptosis compared to NEMO∆hepa livers as well as a dramatic downregulation of genes involved in cell cycle regulation and DNA replication. Consequently, NEMO∆hepa/KEAP1∆hepa compared to NEMOΔhepa livers displayed decreased fibrogenesis, lower tumor incidence, reduced tumor number, and decreased tumor size. Conclusions: NRF2 activation in NASH patients correlates with the grade of inflammation, but not steatosis. Functional analysis in mice demonstrated that NRF2 activation in chronic liver disease is protective by ameliorating fibrogenesis, initiation and progression of hepatocellular carcinogenesis.
2021-05-26 | GSE156838 | GEO
Project description:O-GlcNAcylation is an essential, nutrient-sensitive post-translational modification, but its biochemical and phenotypic effects remain incompletely understood. To address this knowledge gap, we investigated the global transcriptional response to perturbations in O-GlcNAcylation. Unexpectedly, many transcriptional effects of O-GlcNAc transferase (OGT) inhibition were due to the activation of NRF2, the master regulator of redox stress tolerance. Moreover, we found that a signature of low OGT activity strongly correlates with NRF2 activation in multiple tumor expression datasets. Guided by this information, we identified KEAP1 (also known as KLHL19), the primary negative regulator of NRF2, as a direct substrate of OGT. We show that O-GlcNAcylation of KEAP1 at serine 104 is required for the efficient ubiquitination and degradation of NRF2. Interestingly, O-GlcNAc levels and NRF2 activation co-vary in response to glucose fluctuations, indicating that KEAP1 O-GlcNAcylation links nutrient sensing to downstream stress resistance. Our results reveal a novel regulatory connection between nutrient-sensitive glycosylation and NRF2 signaling, and provide a blueprint for future approaches to discover functionally important O-GlcNAcylation events on other KLHL family proteins in various experimental and disease contexts.
2017-06-26 | GSE81740 | GEO