Transcriptomic analysis of a gut epithelial cell line after the depletion of selenoprotein Glutathione peroxidase 4
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE40287 | GEO | 2013/01/01
SECONDARY ACCESSION(S): PRJNA173416
REPOSITORIES: GEO
Similar Datasets
Project description:GPx4 is an important antioxidant gene that is derived from selenium. A ploymorphism in GPx4 has been associated with increased risk of colorectal and prostate cancer. This experiment decsribes the effect of change in GPx4 expression in human intestinal epithelial cell line (Caco-2).Depletion of GPx4 expression led to changes in mitochondrial pathways including oxidative phosphorylation and ubiquinone biosynthesis pathway and genes involved in apoptosis regulation Total RNA obtained from Caco-2 cells following treatment for 72hrs with GPx4 specific siRNA, or a scrambled siRNA control at 60 and 120pmol concentrations.
2013-01-01 | E-GEOD-40287 | biostudies-arrayexpress
Project description:Breast cancer (BC) is one of the most common cancers in women. Evidence suggests that genetic variation in antioxidant enzymes could influence BC risk, but to date the relationship between selenoproteins and BC risk remains unclear. In this report, a study population including 975 Danish cases and 975 controls matched for age and hormone replacement therapy (HRT) use was genotyped for five functional single nucleotide polymorphisms (SNPs) in SEPP1, GPX1, GPX4 and the antioxidant enzyme SOD2 genes. The influence of genetic polymorphisms on breast cancer risk was assessed using conditional logistic regression. Additionally pre-diagnosis erythrocyte GPx (eGPx) activity was measured in a sub-group of the population. A 60% reduction in risk of developing overall BC and ductal BC was observed in women who were homozygous Thr carriers for SEPP1 rs3877899. Additionally, Leu carriers for GPX1 Pro198Leu polymorphism (rs1050450) were at ?2 fold increased risk of developing a non-ductal BC. Pre-diagnosis eGPx activity was found to depend on genotype for rs713041 (GPX4), rs3877899 (SEPP1), and rs1050450 (GPX1) and on HRT use. Moreover, depending on genotype and HRT use, eGPx activity was significantly lower in women who developed BC later in life compared with controls. Furthermore, GPx1 protein levels increased in human breast adenocarcinoma MCF7 cells exposed to ?-estradiol and sodium selenite.In conclusion, our data provide evidence that SNPs in SEPP1 and GPX1 modulate risk of BC and that eGPx activity is modified by SNPs in SEPP1, GPX4 and GPX1 and by estrogens. Our data thus suggest a role of selenoproteins in BC development.
| S-EPMC3769272 | biostudies-literature
Project description:The selenoprotein glutathione peroxidase 4 (GPX4) is one of the main antioxidant mediators in the human body. Its central function involves the reduction of complex hydroperoxides into their respective alcohols often using reduced Glutathione (GSH) as a reducing agent. GPX4 has become a hotspot therapeutic target in biomedical research following its characterization as a chief regulator of ferroptosis, and its subsequent recognition as a specific pharmacological target for the treatment of an extensive variety of human diseases including cancers and neurodegenerative disorders. Several recent studies have provided insights into how GPX4 is distinguished from the rest of the glutathione peroxidase family, the unique biochemical properties of GPX4, how GPX4 is related to lipid peroxidation and ferroptosis, and how the enzyme may be modulated as a potential therapeutic target. This current report aims to review the literature underlying all these insights and present an up-to-date perspective on the current understanding of GPX4 as a potential therapeutic target.
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Project description:Essentially, all patients diagnosed with ovarian cancer (OC) are treated with platinum (Pt); however, Pt resistance (Pt-R) rapidly develops. We show OC cells resistant to Pt increase intracellular cholesterol by increasing expression of the high-density lipoprotein (HDL) receptor, scavenger receptor class B type 1 (SR-B1). Expression of SR-B1 was associated with chemoresistance in OC cells and tumors. SR-B1 blockade using synthetic cholesterol-poor HDL-like nanoparticles (HDL NPs) diminished cholesterol uptake leading to cell death of Pt-R OC cells in vitro and suppressed Pt-R OC tumor growth in vivo. Reduced cholesterol accumulation in Pt-R OC cells induced lipid oxidative stress through reduction of glutathione peroxidase 4 (GPx4) expression leading to ferroptosis. Reduction of GPx4 expression in OC cells re-sensitized Pt-R cells to Pt by reducing cholesterol uptake and enhancing the accumulation of lipid reactive oxygen species (L-ROS). Mechanistically, GPx4 knockdown in OC cells was associated with reduced expression of the histone acetyltransferase EP300, leading to reduced H3K27 acetylation around the SREBP2 promoter suppressing its expression. As SREBP2 regulates SR-B1 transcription, these data demonstrate chemoresistance and cancer cell survival under high ROS burden obligates high GPx4 and SR-B1 expression through SREBP2. Targeting SR-B1 to modulate cholesterol uptake inhibits this axis and causes ferroptosis in vitro and in vivo in Pt-R OC.
2024-06-01 | GSE234404 | GEO
Project description:Selenoprotein P is a hepatokine which is essential for maintaining systemic selenium homeostasis and is used as serum biomarker for the selenium status in humans. In addition to selenium, also copper homeostasis is mainly regulated by the liver coordinating systemic distribution of copper bound to ceruloplasmin or excreting surplus copper into the bile. Circulating selenium and copper concentrations are most often negatively correlating, e.g. during aging copper levels are increasing while selenium levels are decreasing. Based on these results, we addressed the question of how both trace elements interfere with each other using the liver-derived cell line HepG2. We observed that copper treatment resulted in a substantial increase of intracellular selenium concentrations. In parallel, extracellular SELENOP concentrations were drastically reduced while SELENOP accumulated within the cells. The same observation was made when using primary murine hepatocytes. Indeed, SELENOP was one of the proteins most strongly downregulated by copper in an untargeted secretome approach. Accumulation of hepatic copper is a characteristic of Wilson’s disease. Accordingly, SELENOP levels were decreasing in the serum of LPP rats, a model of Wilson’s disease starting at disease onset. Also, Wilson’s disease patients showed reduced serum SELENOP concentrations when circulating copper concentrations were low. This positive correlation between copper and ceruloplasmin and SELENOP was also observed in a GWAS analysis of EPIC-Potsdam samples identifying SNP rs11708215 as a modulating factor. Our data indicate that under conditions of a suboptimal selenium supply combined with a high copper intake a functional selenium deficit can become even worse because peripheral tissues such as the brain depend on SELENOP for their selenium supply.
2023-07-20 | PXD036300 | Pride
Project description:Oxidative stress and mitochondrial dysfunction are known to contribute to the pathogenesis of Parkinson's disease. Dopaminergic neurons may be more sensitive to these stressors because they contain dopamine (DA), a molecule that oxidizes to the electrophilic dopamine quinone (DAQ) which can covalently bind nucleophilic amino acid residues such as cysteine. The identification of proteins that are sensitive to covalent modification and functional alteration by DAQ is of great interest. We have hypothesized that selenoproteins, which contain a highly nucleophilic selenocysteine residue and often play vital roles in the maintenance of neuronal viability, are likely targets for the DAQ. Here we report the findings of our studies on the effect of DA oxidation and DAQ on the mitochondrial antioxidant selenoprotein glutathione peroxidase 4 (GPx4). Purified GPx4 could be covalently modified by DAQ, and the addition of DAQ to rat testes lysate resulted in dose-dependent decreases in GPx4 activity and monomeric protein levels. Exposing intact rat brain mitochondria to DAQ resulted in similar decreases in GPx4 activity and monomeric protein levels as well as detection of multiple forms of DA-conjugated GPx4 protein. Evidence of both GPx4 degradation and polymerization was observed following DAQ exposure. Finally, we observed a dose-dependent loss of mitochondrial GPx4 in differentiated PC12 cells treated with dopamine. Our findings suggest that a decrease in mitochondrial GPx4 monomer and a functional loss of activity may be a contributing factor to the vulnerability of dopaminergic neurons in Parkinson's disease.
| S-EPMC4043454 | biostudies-literature
Project description:Plasma glutathione peroxidase (GPx-3) is a selenocysteine-containing extracellular antioxidant protein that catalyzes the reduction of hydrogen peroxide and lipid hydroperoxides. Selenoprotein expression involves the alternate recognition of a UGA codon as a selenocysteine codon and requires signals in the 3'-untranslated region (UTR), including a selenocysteine insertion sequence (SECIS), as well as specific translational cofactors. To ascertain regulatory determinants of GPx-3 expression and function, we generated recombinant GPx-3 (rGPX-3) constructs with various 3'-UTR, as well as a Sec73Cys mutant. In transfected Cos7 cells, the Sec73Cys mutant was expressed at higher levels than the wild type rGPx-3, although the wild type rGPx-3 had higher specific activity, similar to plasma purified GPx-3. A 3'-UTR with only the SECIS was insufficient for wild type rGPx-3 protein expression. Selenocompound supplementation and co-transfection with SECIS binding protein 2 increased wild type rGPx-3 expression. These results demonstrate the importance of translational mechanisms in GPx-3 expression.
| S-EPMC2693281 | biostudies-literature
Project description:Selenoproteins are a small family of proteins containing the trace element selenium in form of the rare amino acid selenocysteine (Sec), which is decoded by the UGA codon. In humans, a number of pathogenic mutations in genes encoding distinct selenoproteins or selenoprotein biosynthesis factors have been identified. Pathogenic mutations in selenocysteine synthase (SEPSECS), which catalyzes the last step in Sec-tRNA[Ser]Sec biosynthesis, were reported in children suffering from progressive cerebello-cerebral atrophy. To understand the underlying mechanisms of SEPSECS mutations, we generated a novel mouse model recapitulating the respective human pathogenic Y334C mutation in the murine Sepsecs gene (SepsecsY334C). Unlike in patients, homozygous mutant pups died perinatally with signs of cardio-respiratory failure. Perinatal death is reminiscent of the Sedaghatian spondylometaphyseal dysplasia disorder in humans, which is caused by inactivating mutations of the gene encoding the selenoprotein and key ferroptosis regulator glutathione peroxidase 4 (GPX4). Protein expression levels of distinct selenoproteins in SepsecsY334C/Y334C mice were found to be generally reduced in brain and isolated cortical neurons, while transcriptomics analysis uncovered an upregulation of NRF2-regulated genes. Crossbreeding of SepsecsY334C/Y334C mice with mice harboring a targeted mutation of the catalytically active site Sec to Cys in GPX4 surprisingly rescued perinatal death of SepsecsY334C/Y334C mice, showing that the cardio-respiratory defects of Sepsecs-mutant mice were caused by the lack of GPX4. Like in SepsecsY334C/Y334C mice, selenoprotein expression levels remained low and NRF2-regulated genes remained highly expressed in these compound mutant mice, indicating that selenium-independent GPX4, along with a sustained antioxidant response are sufficient to compensate for dysfunctional Sec-tRNA[Ser]Sec biosynthesis. Our findings imply that children with mutations in SEPSECS or GPX4 may benefit from treatments partially compensating for impaired GPX4 activity.
2021-11-24 | GSE181852 | GEO
Project description:Selenium-binding protein (SBP) 1 is present in reduced levels in several cancer types as compared with normal tissues, and lower levels are associated with poor clinical prognosis. Another selenium-containing protein, glutathione peroxidase 1 (GPX1), has been associated with cancer risk and development. The interaction between these representatives of different classes of selenoproteins was investigated. Increasing SBP1 levels in either human colorectal or breast cancer cells by transfection of an expression construct resulted in the reduction of GPX1 enzyme activity. Increased expression of GPX1 in the same cell types resulted in the transcriptional and translational repression of SBP1, as evidenced by the reduction of SBP1 messenger RNA and protein and the inhibition of transcription measured using an SBP1 reporter construct. The opposing effects of SBP1 and GPX1 on each other were also observed when GPX1 was increased by supplementing the media of these tissue culture cells with selenium, and the effect of selenium on SBP1 was shown to be GPX1 dependent. Decreasing or increasing GPX1 levels in colonic epithelial cells of mice fed a selenium-deficient, -adequate or -supplemented diet resulted in the opposing effect on SBP1 levels. These data are explained in part by the demonstration that SBP1 and GPX1 form a physical association, as determined by coimmunoprecipitation and fluorescence resonance energy transfer assay. The results presented establish an interaction between two distinct selenium-containing proteins that may enhance the understanding of the mechanisms by which selenium and selenoproteins affect carcinogenesis in humans.
| S-EPMC2915633 | biostudies-literature
Project description:We previously reported a depletion of murine regenerating islet-derived protein 2 (REG2) in pancreatic islets of glutathione peroxidase-1 (Gpx1) overexpressing (OE) mice. The present study was to explore if and how the REG2 depletion contributed to an augmented glucose stimulated insulin secretion (GSIS) in OE islets. After we verified a consistent depletion (90%, p < 0.05) of REG2 mRNA, transcript, and protein in OE islets compared with wild-type (WT) controls, we treated cultured and perifused OE islets (70 islets/sample) with REG2 (1 μg/ml or ml · min) and observed 30-40% (p < 0.05) inhibitions of GSIS by REG2. Subsequently, we obtained evidences of co-immunoprecipitation, cell surface ligand binding, and co-immunofluorescence for a ligand-receptor binding between REG2 and transmembrane, L-type voltage-dependent Ca2+ channel (CaV1.2) in beta TC3 cells. Mutating the C-type lectin binding domain of REG2 or deglycosylating CaV1.2 removed the inhibition of REG2 on GSIS and(or) the putative binding between the two proteins. Treating cultured OE and perifused WT islets with REG2 (1 μg/ml or ml · min) decreased (p < 0.05) Ca2+ influx triggered by glucose or KCl. An intraperitoneal (ip) injection of REG2 (2 μg/g) to OE mice (6-month old, n = 10) decreased their plasma insulin concentration (46%, p < 0.05) and elevated their plasma glucose concentration (25%, p < 0.05) over a 60 min period after glucose challenge (ip, 1 g/kg). In conclusion, our study identifies REG2 as a novel regulator of Ca2+ influx and insulin secretion, and reveals a new cascade of GPX1/REG2/CaV1.2 to explain how REG2 depletion in OE islets could decrease its binding to CaV1.2, resulting in uninhibited Ca2+ influx and augmented GSIS. These findings create new links to bridge redox biology, tissue regeneration, and insulin secretion.
| S-EPMC9463454 | biostudies-literature