Sensor Systems of KEAP1 Uniquely Detecting Oxidative and Electrophilic Stresses Separately In Vivo
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PROVIDER: PRJNA1159162 | ENA |
REPOSITORIES: ENA
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Project description:In the KEAP1-NRF2 stress response system, KEAP1 acts as a sensor for oxidative and electrophilic stresses through formation of S-S bond and C-S bond, respectively. Of the many questions left related to the sensor activity, following three appear important; whether these KEAP1 sensor systems are operating in vivo, whether oxidative and electrophilic stresses are sensed by the similar or distinct systems, and how KEAP1 equips highly sensitive mechanisms detecting oxidative and electrophilic stresses in vivo. To address these questions, we conducted a series of analyses utilizing KEAP1-cysteine substitution mutant mice, conditional selenocysteine-tRNA (Trsp) knockout mice, and human cohort whole genome sequence (WGS) data. The Trsp-knockout provokes severe deficiency of selenoproteins and compensatory activation of NRF2. However, mice lacking homozygously a pair of critical oxidative stress sensor cysteine residues of KEAP1 fail to activate NRF2 in the Trsp-knockout livers. Secondly, this study provides evidence for the differential utilization of KEAP1 sensors for oxidative and electrophilic stresses in vivo. Thirdly, theoretical calculations show that the KEAP1 dimer equips quite sensitive sensor machinery in which modification of a single molecule of KEAP1 within the dimer is sufficient to affect the activity. WGS examinations of rare variants identified seven non-synonymous variants in the oxidative stress sensors in human KEAP1, while no variant was found in electrophilic sensor cysteine residues, supporting the fail-safe nature of the KEAP1 oxidative stress sensor activity. These results provide valuable information for our understanding how mammals respond to oxidative and electrophilic stresses efficiently.
2024-10-09 | GSE276818 | GEO
Project description:KEAP1, a cytoplasmic repressor of the oxidative stress responsive transcription factor NRF2, senses the presence of electrophilic agents by modification of its sensor cysteine residues. In addition to xenobiotics, several reactive metabolites have been shown to covalently modify key cysteines on KEAP1, although the full repertoire of these molecules and their respective modifications remains undefined. Here, we report the discovery of sAKZ692, a small molecule identified by high throughput screening that stimulates NRF2 transcriptional activity in cells by inhibiting the glycolytic enzyme pyruvate kinase. sAKZ692 treatment promotes the buildup of glyceraldehyde 3-phosphate, a metabolite which leads to S-lactate modification of cysteine sensor residues of KEAP1, resulting in NRF2 dependent transcription. This work identifies a novel posttranslational modification of cysteine derived from a reactive central carbon metabolite and helps further define the complex relationship between metabolism and the oxidative stress sensing machinery of the cell.
2023-05-01 | GSE230577 | GEO
Project description:The Keap1-Nrf2 system is the major regulatory pathway of cytoprotective gene expression against oxidative and/or electrophilic stresses. Keap1 acts as a stress sensor protein in this system. While Keap1 constitutively suppresses Nrf2 activity under unstressed conditions, oxidants or electrophiles provoke the repression of Keap1 activity, inducing the Nrf2 activation. However, the precise molecular mechanisms behind the liberation of Nrf2 from Keap1 repression in the presence of stress remain to be elucidated. We hypothesized that oxidative and electrophilic stresses induce the nuclear accumulation of Nrf2 by affecting the Keap1-mediated rapid turnover of Nrf2, since such accumulation was diminished by the protein synthesis inhibitor cycloheximide. While both the Cys273 and Cys288 residues of Keap1 are required for suppressing Nrf2 nuclear accumulation, treatment of cells with electrophiles or mutation of these cysteine residues to alanine did not affect the association of Keap1 with Nrf2 either in vivo or in vitro. Rather, these treatments impaired the Keap1-mediated proteasomal degradation of Nrf2. These results support the contention that Nrf2 protein synthesized de novo after exposure to stress accumulates in the nucleus by bypassing the Keap1 gate and that the sensory mechanism of oxidative and electrophilic stresses is closely linked to the degradation mechanism of Nrf2.
| S-EPMC1317630 | biostudies-literature
Project description:KEAP1 overexpressed and NRF2 siRNA knockdown A549 NSCLC cells were used to identify downstream genes of NRF2 pathway separately and by combinatorial analysis. We used triplicate microarrays of transfected A549 cells with mKeap1-GFP for overexpression, siRNAs targeting NRF2 for knockdown and siGFP as control respectively. As a result, we identified several genes which are involved in cancer metabolic functions in these cells. We used microarrays to identify the gene downregulated in both KEAP1 overexpressed and NRF2 siRNA knockdown A549 NSCLC cells and found a subset of downregulated genes which are involved in metabolic functions.
2017-08-02 | GSE94393 | GEO
Project description:We investigated how selective mutation in STK11 or KEAP1 alters the transcriptional profile of cancer cells, and how the transcriptional profile of co-mutant cells might uniquely affect cancer-related pathways including control of proliferative potential, metabolic homeostasis, and cell death. We performed bulk RNAseq on none, single or double mutation of these genes in single cell knockout clones (n=3 per group) from both H358 and H292 cell lines.
2020-11-12 | E-MTAB-9724 | biostudies-arrayexpress
Project description:To compare hepatic gene expression in conditional Keap1 knockout (Alb-Cre:Keap1(flox/-)) and genetic control mice. Disruption of Keap1-mediated repression of Nrf2 signaling was expected to result in increased expression of Nrf2-regulated genes. Keywords: comparative expression profiling
2008-05-01 | GSE11287 | GEO
Project description:We analyzed the esophagus of Keap1 conditional knockout mice. In these mice, there were both Keap1-normal and Keap1-deleted cells in the esophageal epithelium. To compare the gene expression of these cells, we conducted single-cell RNA-seq for the mice esophagus.
2023-02-19 | GSE197558 | 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:This SuperSeries is composed of the following subset Series: GSE30645: Expression analysis of the singlet oxygen resistant 1 (sor1) mutant GSE30646: Response of Chlamydomonas reinhardtii to different oxidative and electrophilic stress conditions Refer to individual Series
2011-07-14 | E-GEOD-30648 | biostudies-arrayexpress
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