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Effect of NFE2L2 silencing on miRNA profile of human aortic endothelial cells (HAECs) in response to GDF-15 and SDF-1

ABSTRACT: 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, and preventing 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 Thus, regarding the function of Nrf2 as a protein sequestering Keap1, both published and unpublished data on Nrf2-Keap1 duet may gain new interpretation.

ORGANISM(S): Homo sapiens

PROVIDER: GSE109312 | GEO | 2019/01/17

REPOSITORIES: GEO

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Project description:ABSTRACT Rationale Premature senescence is conducive to aging and cardiovascular diseases. Nrf2 transcription factor, the master orchestrator of adoptive response to cellular stress, has been implicated in regulation of premature senescence in fibroblasts, neural and mesenchymal stem cells by transactivation of antioxidant gene expression. However, as we show here, human primary endothelial cells (ECs) devoid of Nrf2 and murine Nrf2 transcriptional knockout (tKO) aortas are senescent but do not encounter oxidative stress and damage, what contradicts this mechanism. Moreover, a molecular switch between normal, senescent and apoptotic fate remains unknown. Objective To elucidate the mechanism of Nrf2-related premature senescence of vascular system, to understand why Nrf2 deregulation does not cause oxidative stress exclusionary in ECs and to indicate a molecular switch determining ECs fate. Methods and Results Herein we evidence that ECs deficient in Nrf2 protein, or with limited Nrf2 activity in shear stress conditions, exhibit excessive S-nitrosylation of proteins. It is also a characteristic of Nrf2 tKO murine aortas, as determined by biotin switch assay in situ. Mass spectrometry analysis reveals that NOX4 is S-nitrosylated exclusively in ECs devoid of Nrf2. A functional role of S-nitrosylation is protection of ECs from death by inhibition of NOX4-mediated oxidative damage. As a result Nrf2-deficient ECs preserve oxidative balance but are redirected to premature senescence. The same phenotype is seen in Nrf2 tKO aortas. These effects are mediated by Keap1, a direct binding partner of Nrf2 and repressor of its transcriptional activity, remaining in cytoplasm unrestrained by Nrf2. S-nitrosylation, followed by senescence, can also be triggered in smooth muscle cells (SMCs) by EC-derived paracrine induction of iNOS. Conclusions Collectively, Keap1-dependent S-nitrosylation of NOX4 hampers oxidative detriment in ECs with disturbed Nrf2 signaling and may provide defence in the adjacent aortic cells. Overabundance of unrestrained Keap1 in the cytoplasm determines fate of ECs.

Project description:Nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcription factor that induces a battery of cytoprotective genes in response to oxidative/electrophilic stress. Kelch-like ECH associating protein 1 (Keap1) sequesters Nrf2 in the cytosol. The purpose of this study was to investigate the role of Nrf2 in regulating the mRNA of genes encoding drug metabolizing enzymes and xenobiotic transporters. Microarray analysis was performed in livers of Nrf2-null, wild-type, Keap1-knockdown mice with increased Nrf2 activation, and Keap1-hepatocyte knockout mice with maximum Nrf2 activation. In general, Nrf2 did not have a marked effect on uptake transporters, but the mRNAs of organic anion transporting polypeptide 1a1, sodium taurocholate cotransporting polypeptide, and organic anion transporter 2 were decreased with Nrf2 activation. The effect of Nrf2 on cytochrome P450 (Cyp) genes was minimal, with only Cyp2a5, Cyp2c50, Cyp2c54, and Cyp2g1 increased, and Cyp2u1 decreased with enhanced Nrf2 activation. However, Nrf2 increased mRNA of many other phase-I enzymes, such as aldo-keto reductases, carbonyl reductases, and aldehyde dehydrogenase 1. Many genes involved in phase-II drug metabolism were induced by Nrf2, including glutathione S -transferases, UDP- glucuronosyltransferases, and UDP-glucuronic acid synthesis enzymes. Efflux transporters, such as multidrug resistance-associated proteins, breast cancer resistant protein, as well as ATP-binding cassette g5 and g8 were induced by Nrf2. In conclusion, Nrf2 markedly alters hepatic mRNA of a large number of drug metabolizing enzymes and xenobiotic transporters, and thus Nrf2 plays a central role in xenobiotic metabolism and detoxification. We used microarrays to detail the global programme of gene expression in response to Nrf2 activation and identified distinct classes of up- and down-regulated genes. process. Gene expression in livers of Nrf2-null, WT, Keap1-KD, and Keap1-HKO mice was determined using Affymetrix Mouse 430.20 arrays by the KUMC Microarray Core Facility. Biological cRNA replicates (n=3) of each genotype were hybridized to an individual array.

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Effect of NFE2L2 silencing on miRNA profile of human aortic endothelial cells (HAECs) in response to GDF-15 and SDF-1

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