| 1. |
- Birgersson, Madeleine, et al.
(author)
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ERβ in Granulosa Cell Tumors and Its Clinical Potential
- 2023
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In: Endocrinology. - : The Endocrine Society. - 0013-7227 .- 1945-7170. ; 164:6
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Research review (peer-reviewed)abstract
- Granulosa cell tumors (GCTs) are rare ovarian tumors comprising an adult and a juvenile subtype. They have a generally good prognosis, but the survival rate drastically declines in patients with late-stage or recurring tumors. Due to the rarity of GCTs, the tumor type is largely understudied and lacks a specific treatment strategy. Estrogen receptor beta (ERβ/ESR2) has been found to be highly expressed in GCTs, which could be of therapeutic importance since it can be targeted with small molecules. However, its role in GCTs is not known. In this review, we summarize the current knowledge about the action of ERβ in the ovary and discuss its prospective role in GCTs.
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| 2. |
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| 3. |
- Brundin, Peik M.A., et al.
(author)
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Blood hormones and torque teno virus in peripheral blood mononuclear cells
- 2020
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In: Heliyon. - : Elsevier. - 2405-8440. ; 6:11
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Journal article (peer-reviewed)abstract
- Men and women respond differently to infectious diseases. Women show less morbidity and mortality, partially due to the differences in sex hormone levels which can influence the immune response. Torque teno virus (TTV) is non-pathogenic and ubiquitously present in serum from a large proportion (up to 90%) of adult humans with virus levels correlating with the status of the host immune response. The source of TTV replication is unknown, but T-lymphocytes have been proposed. In this study we investigated the presence and levels of TTV in peripheral blood mononuclear cells (PBMCs) in premenopausal (pre-MP) women, post-menopausal (post-MP) women, and men, and determined their serum sex hormone levels. Of the examined subjects (n = 27), we found presence of TTV in PMBC from 17.6% pre-MP (n = 17), 25.0% post-MP (n = 4) and 50.0% men (n = 6). The levels of TTV/μg DNA were lower among TTV-positive men and post-MP women compared to pre-MP women. All the positive pre-MP women were either anovulatory, hypothyroid, or both. In addition, the TTV-positive pre-MP women had significantly lower progesterone levels compared to TTV-negative pre-MP women. Although our study was performed on a limited number of subjects, the data suggests that TTV in PBMC is associated with an anovulatory menstrual cycle with low progesterone levels, and possibly with male sex.
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| 4. |
- Brundin, Peik M. A., 1975-
(author)
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Sex differences in immune response and sex hormone receptor expression in healthy individuals and during viral infection
- 2021
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Doctoral thesis (other academic/artistic)abstract
- There is sex-bias in morbidity and mortality from infectious diseases. Infections kill more men than women and several studies have pointed out differences in the immune system as a reason. The sex hormones estrogen, progesterone and testosterone all shape the effect of the immune response on multiple levels. Women at fertile age have been suggested to have higher proinflammatory responses from inflammatory stimuli compared to men and post-menopausal women, which has been ascribed to their higher estrogen levels. This could possibly lead to a more active pathogen response but may also result in a detrimental immunopathology to infections or development of autoimmune reaction.The overall aim of this thesis is to study the contribution of sex hormones and sex hormone receptors (SHR) to sex differences in immune response. We focus on peripheral blood mononuclear cells (PBMCs) to study such relationships in healthy individuals, as well as in individuals with asymptomatic Torque Teno Virus infection, and individuals with acute Puumala virus infection.In Paper I, we investigated expression of SHR and immune response genes in PBMC from healthy premenopausal (pre-MP) women during the menstrual cycle. The expression levels were estimated using a qPCR Array (Taqman low-density array, TLDA). SHR expression did not change significantly during the menstrual cycle, but several key immune regulatory genes were significantly more expressed during the ovulatory and mid luteal phase. Further, we separated PBMC into cell subsets (CD4+ T-cells, CD8+ T-cells, CD56+ NK-cells, CD14+ monocytes and CD19+ B-cells) and analyzed the expression through qPCR of estrogen receptors (ERs), ERα, ERβ1 (wildtype) and the isoform ERβ2. For the first time and unexpectedly, we demonstrate that the isoform ERβ2 was more abundant than wildtype ERβ1. The data from this paper provides new knowledge on the contribution of the menstrual cycle on immune response.In Paper II, we explored the use of Torque Teno Virus as a secondary functional immune marker in men and women. Expression of viral TTV DNA in PBMCs was estimated using a qPCR kit from Argene (R-gene) and analyzed in relation to serum sex hormone levels. The results showed that 50% of the men, 25% the post-MP women, and 18% of the pre-MP women were TTV+. Interestingly, all pre-MP women that were TTV+ had hormonal aberrances and were either anovulatory and/or hypothyroid. TTV+ pre-MP women also had significantly lower progesterone levels than TTV- pre-MP women. This paper indicates that the prevalence of TTV in PBMC differs between men, pre-MP and post-MP women. Furthermore, hormonal aberrances (at least in pre-MP women) will lead to increased prevalence of TTV.In Paper III we investigated the expression of ERα, ERβ1 and ERβ2 in PBMC from patients with Nephropathia epidemica, the viral zoonotic disease caused by Puumala virus, a Hanta virus known to affect more men than women. Expression of ERs in PBMCs and clinical laboratory results during the acute and convalescent phases were analyzed using a principal component analysis (PCA). The results show differences in ER expression and support previous findings that men and women have a different clinical pictureIn conclusion, the results in this thesis reveal distinct patterns of immune response related to sex hormone levels, SHR expression and the phases of the menstrual cycle supporting that there a link between sex hormone levels and immune responses. Further, we show that the ER isoform ERβ2 is more abundant in PBMCs than what was previously described. The data in this thesis adds to the knowledge to the sex differences in immune response and exemplifies the importance of taking these differences into account in the clinic.
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| 5. |
- Brundin, Peik M., et al.
(author)
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Expression of Sex Hormone Receptor and Immune Response Genes in Peripheral Blood Mononuclear Cells During the Menstrual Cycle
- 2021
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In: Frontiers in Endocrinology. - : Frontiers Media S.A.. - 1664-2392. ; 12
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Journal article (peer-reviewed)abstract
- Sex hormones are known to interact with the immune system on multiple levels but information on the types of sex hormone receptors (SHR) and their expression levels in immune cells is scarce. Estrogen, testosterone and progesterone are all considered to interact with the immune system through their respective cell receptors (ERα and ERβ including the splice variant ERβ2, AR and PGR). In this study expression levels of SHR genes in peripheral blood mononuclear cells (PBMCs) and cell subsets (CD4+ and CD8+ T-cells, CD56+ NK-cells, CD14+ monocytes and CD19+ B-cells) were analyzed using standard manual qPCR or a qPCR array (TLDA). Nine healthy individuals including men (n = 2), premenopausal (Pre-MP, n = 5) and postmenopausal (post-MP, n = 2) women were sampled for PBMCs which were separated to cell subsets using FACS. Ten Pre-MP women were longitudinally sampled for total PBMCs at different phases of the menstrual cycle. We found that ERα was most abundant and, unexpectedly, that ERβ2 was the dominant ERβ variant in several FACS sorted cell subsets. In total PBMCs, SHR (ERα, ERβ1, ERβ2, and AR) expression did not fluctuate according to the phase of the menstrual cycle and PGR was not expressed. However, several immune response genes (GATA3, IFNG, IL1B, LTA, NFKB1, PDCD1, STAT3, STAT5A, TBX21, TGFB1, TNFA) were more expressed during the ovulatory and mid-luteal phases. Sex hormone levels did not correlate significantly with gene expression of SHR or immune response genes, but sex hormone-binding globulin (SHBG), a steroid hormone transporting protein, was positively correlated to expression of ERβ1 gene. This study provides new insights in the distribution of ERs in immune cells. Furthermore, expression patterns of several immune response genes differ significantly between phases of the menstrual cycle, supporting a role for sex hormones in the immune response.
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| 6. |
- Latorre-Leal, María, et al.
(author)
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CYP46A1-mediated cholesterol turnover induces sex-specific changes in cognition and counteracts memory loss in ovariectomized mice
- 2024
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In: Science advances. - 2375-2548. ; 10:4
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Journal article (peer-reviewed)abstract
- The brain-specific enzyme CYP46A1 controls cholesterol turnover by converting cholesterol into 24S-hydroxycholesterol (24OH). Dysregulation of brain cholesterol turnover and reduced CYP46A1 levels are observed in Alzheimer's disease (AD). In this study, we report that CYP46A1 overexpression in aged female mice leads to enhanced estrogen signaling in the hippocampus and improved cognitive functions. In contrast, age-matched CYP46A1 overexpressing males show anxiety-like behavior, worsened memory, and elevated levels of 5α-dihydrotestosterone in the hippocampus. We report that, in neurons, 24OH contributes to these divergent effects by activating sex hormone signaling, including estrogen receptors. CYP46A1 overexpression in female mice protects from memory impairments induced by ovariectomy while having no effects in gonadectomized males. Last, we measured cerebrospinal fluid levels of 24OH in a clinical cohort of patients with AD and found that 24OH negatively correlates with neurodegeneration markers only in women. We suggest that CYP46A1 activation is a valuable pharmacological target for enhancing estrogen signaling in women at risk of developing neurodegenerative diseases.
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| 7. |
- Lupu, Diana, et al.
(author)
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Fluoxetine Affects Differentiation of Midbrain Dopaminergic Neurons In Vitro
- 2018
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In: Molecular Pharmacology. - New York : American Society for Pharmacology and Experimental Therapeutics. - 0026-895X .- 1521-0111. ; 94:4, s. 1220-1231
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Journal article (peer-reviewed)abstract
- Recent meta-analyses found an association between prenatal exposure to the antidepressant fluoxetine (FLX) and an increased risk of autism in children. This developmental disorder has been related to dysfunctions in the brains' rewards circuitry, which, in turn, has been linked to dysfunctions in dopaminergic (DA) signaling. The present study investigated if FLX affects processes involved in dopaminergic neuronal differentiation. Mouse neuronal precursors were differentiated into midbrain dopaminergic precursor cells (mDPCs) and concomitantly exposed to clinically relevant doses of FLX. Subsequently, dopaminergic precursors were evaluated for expression of differentiation and stemness markers using quantitative polymerase chain reaction. FLX treatment led to increases in early regional specification markers orthodenticle homeobox 2 (Otx2) and homeobox engrailed-1 and -2 (En1 and En2). On the other hand, two transcription factors essential for midbrain dopaminergic (mDA) neurogenesis, LIM homeobox transcription factor 1 alpha (Lmx1a) and paired-like homeodomain transcription factor 3 (Pitx3) were downregulated by FLX treatment. The stemness marker nestin (Nes) was increased, whereas the neuronal differentiation marker beta 3-tubulin (Tubb3) decreased. Additionally, we observed that FLX modulates the expression of several genes associated with autism spectrum disorder and downregulates the estrogen receptors (ERs) alpha and beta. Further investigations using ER beta knockout (BERKO) mDPCs showed that FLX had no or even opposite effects on several of the genes analyzed. These findings suggest that FLX affects differentiation of the dopaminergic system by increasing production of dopaminergic precursors, yet decreasing their maturation, partly via interference with the estrogen system.
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| 8. |
- Madeja, Zbigniew, et al.
(author)
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The role of thioredoxin reductase activity in selenium-induced cytotoxicity
- 2005
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In: Biochemical Pharmacology. - : Elsevier. - 0006-2952 .- 1356-1839. ; 69:12, s. 1765-1772
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Journal article (peer-reviewed)abstract
- The selenoprotein thioredoxin reductase is a key enzyme in selenium metabolism, reducing selenium compounds and thereby providing selenide to synthesis of all selenoproteins. We evaluated the importance of active TrxR1 in selenium-induced cytotoxicity using transfected TrxR1 over-expressing stable Human Embryo Kidney (HEK-293) cells and modulation of activity by pretreatment with low concentration of selenite. Treatment with sodium selenite induced cytotoxity in a dose-dependent manner in both TrxR1 over-expressing and control cells. However, TrxR1 over-expressing cells, which were preincubated for 72h with 0.1 microM selenite, were significantly more resistant to selenite cytotoxicity than control cells. To demonstrate the early effects of selenite on behaviour of HEK-293 cells, we also investigated the influence of this compound on cell motility. We observed inhibition of cell motility by 50 microM selenite immediately after administration. Moreover, TrxR1 over-expressing cells preincubated with a low concentration of selenite were more resistant to the inhibitory effect of 50 microM selenite than those not preincubated. It was also observed that the TrxR over-expressing cells showed higher TrxR1 activity than control cells and the preincubation of over-expressing cells with 0.1 microM selenite induced further significant increase in the activity of TrxR1. On the other hand, we demonstrated that TrxR1 over-expressing cells showed decreased glutathione peroxidase activity compared to control cells. These data strongly suggest that TrxR1 may be a crucial enzyme responsible for cell resistance against selenium cytotoxicity.
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| 9. |
- Nalvarte, Ivan
(author)
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Functional characterization of cytosolic and mitochondrial thioredoxin reductases
- 2006
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Doctoral thesis (other academic/artistic)abstract
- Mammalian thioredoxin reductases (TrxRs) are homodimeric selenoproteins belonging to the nucleotide oxidoreductase family. They contain a C-terminal penultimate selenocysteine residue, which is kept reduced by the N-terminal redox active site, CVNVGC, of the adjacent subunit. The low pKa, of the selenocysteine residue, in combination with its Cterminal accessibility, gives TrxRs broad substrate specificity. The main substrates of TrxRs are thioredoxins (Trxs), which are reduced using NADPH as an electron donor. Trx can then act as a general protein-disulfide reductase and reduce a variety of substrates. This constitutes the thioredoxin system. Apart from the classical cytosolic thioredoxin system, there exists a complete thioredoxin system exclusively in mitochondria with its own thioredoxin (Trx2) and thioredoxin reductase (TrxR2). In this thesis, we describe the functional characterization of the cytosolic and mitochondrial thioredoxin reductases. It has been suggested that there exists a link between selenium and vitamin E in the protection against lipid membrane peroxidation. Here, we present evidence that TrxR1 is a major reducer of ubiquinone, a regenerator of vitamin E. This reduction is entirely selenium dependent, and puts forward TrxR1 as an important enzyme in the antioxidant defence of lipid membranes. Furthermore, we show that cell lines overexpressing TrxR2 have a higher viability than control cells upon complex III inhibition. This effect may be ascribed to the reduction of cytochrome c by TrxR2, since this would allow electrons to bypass complex III via TrxR2. Indeed, we demonstrate that TrxR2 is a potent reducer of cytochrome c. In addition, we show that cells overexpressing TrxRs have a surprising elevated expression of markers associated with differentiation, compared to control cells. This effect is evident for both the classic cytosolic form, TrxR1a, and its cytosolic splice variant TrxR1b. Expression of TrxR1a and TrxR1b apparently preceds the expression of the genes associated with differentiation, suggesting TrxRs to be involved in the early onset of differentiation. Furthermore, some genes are oppositely regulated by TrxR1a and TrxR1b, implying attentiveness in future TrxR1 gene silencing experiments. In summary, the results presented in this thesis give better understanding of the functions of TrxRs. Our work illustrates the diverse roles of TrxRs, from mediators of redox homeostasis in distinct cellular compartments to their implications in gene expression pathways. The role of TrxRs in these redox regulatory mechanisms are far from resolved and, as reflected in this thesis, much more work is needed in this field of research.
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| 10. |
- Nalvarte, Ivan, et al.
(author)
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Human mitochondrial thioredoxin reductase reduces cytochrome c and confers resistance to complex III inhibition
- 2004
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In: Free Radical Biology & Medicine. - : Elsevier. - 0891-5849 .- 1873-4596. ; 36:10, s. 1270-1278
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Journal article (peer-reviewed)abstract
- The ubiquitously expressed mammalian thioredoxin reductases are selenoproteins that together with NADPH regenerate active reduced thioredoxins and are involved in diverse actions mediated by redox control. Two main forms of mammalian thioredoxin reductases have been isolated, one cytosolic (TrxR1) and one present in mitochondria (TrxR2). Although the principal target for TrxRs is thioredoxin, the cytosolic form can regenerate several important antioxidants such as ascorbic acid, lipoic acid, and ubiquinone. In this study we demonstrate that cytochrome c is a substrate for both TrxR1 and TrxR2. In addition, cells overexpressing TrxR2 are more resistant to impairment of complex III in the mitochondrial respiratory chain upon both antimycin A and myxothiazol treatments, suggesting a complex III bypassing function of TrxR2. Furthermore, we show that cytochrome c is reduced by TrxR2 in vitro, not only by using NADPH as an electron donor but also by using NADH, pointing at TrxR2 as an important redox protein on complex III impairment. These findings may be valuable in understanding respiratory disorders in mitochondrial diseases.
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| 11. |
- Nalvarte, Ivan, et al.
(author)
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Overexpression of enzymatically active human cytosolic and mitochondrial thioredoxin reductase in HEK-293 cells : Effect on cell growth and differentiation
- 2004
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In: Journal of Biological Chemistry. - : American Society for Biochemistry and Molecular Biology. - 0021-9258 .- 1083-351X. ; 279:52, s. 54510-54517
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Journal article (peer-reviewed)abstract
- The mammalian thioredoxin reductases (TrxR) are selenoproteins containing a catalytically active selenocysteine residue (Sec) and are important enzymes in cellular redox control. The cotranslational incorporation of Sec, necessary for activity, is governed by a stem-loop structure in the 3'-untranslated region of the mRNA and demands adequate selenium availability. The complicated translation machinery required for Sec incorporation is a major obstacle in isolating mammalian cell lines stably overexpressing selenoproteins. In this work we report on the development and characterization of stably transfected human embryonic kidney 293 cells that overexpress enzymatically active selenocysteine-containing cytosolic TrxR1 or mitochondrial TrxR2. We demonstrate that the overexpression of selenium-containing TrxR1 results in lower expression and activity of the endogenous selenoprotein glutathione peroxidase and that the activity of overexpressed TrxRs, rather than the protein amount, can be increased by selenium supplementation in the cell growth media. We also found that the TrxR-overexpressing cells grew slower over a wide range of selenium concentrations, which was an effect apparently not related to increased apoptosis nor to fatally altered intracellular levels of reactive oxygen species. Most surprisingly, the TrxR1- or TrxR2-overexpressing cells also induced novel expression of the epithelial markers CK18, CK-Cam5.2, and BerEP4, suggestive of a stimulation of cellular differentiation.
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| 12. |
- Nalvarte, Ivan, et al.
(author)
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The expression and activity of thioredoxin reductase 1 splice variants v1 and v2 regulate the expression of genes associated with differentiation and adhesion
- 2015
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In: Bioscience Reports. - : PORTLAND PRESS LTD. - 0144-8463 .- 1573-4935. ; 35:e00269
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Journal article (peer-reviewed)abstract
- The mammalian redox-active selenoprotein thioredoxin reductase (TrxR1) is a main player in redox homoeostasis. It transfers electrons from NADPH to a large variety of substrates, particularly to those containing redox-active cysteines. Previously, we reported that the classical form of cytosolic TrxR1 (TXNRD1_v1), when overexpressed in human embryonic kidney cells (HEK-293), prompted the cells to undergo differentiation [Nalvarte et al. (2004) J. Biol. Chem. 279, 54510-54517]. In the present study, we show that several genes associated with differentiation and adhesion are differentially expressed in HEK-293 cells stably overexpressing TXNRD1_v1 compared with cells expressing its splice variant TXNRD1_v2. Overexpression of these two splice forms resulted in distinctive effects on various aspects of cellular functions including gene regulation patterns, alteration of growth rate, migration and morphology and susceptibility to selenium-induced toxicity. Furthermore, differentiation of the neuroblastoma cell line SH-SY5Y induced by all-trans retinoic acid (ATRA) increased both TXNRD1_v1 and TXNRD1_v2 expressions along with several of the identified genes associated with differentiation and adhesion. Selenium supplementation in the SH-SY5Y cells also induced a differentiated morphology and changed expression of the adhesion protein fibronectin 1 and the differentiation marker cadherin 11, as well as different temporal expression of the studied TXNRD1 variants. These data suggest that both TXNRD1_v1 and TXNRD1_v2 have distinct roles in differentiation, possibly by altering the expression of the genes associated with differentiation, and further emphasize the importance in distinguishing each unique action of different TrxR1 splice forms, especially when studying the gene silencing or knockout of TrxR1.
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| 13. |
- Nordman, Tomas, et al.
(author)
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Regeneration of the antioxidant ubiquinol by lipoamide dehydrogenase, thioredoxin reductase and glutathione reductase
- 2003
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In: Biofactors. - : IOS Press. - 0951-6433 .- 1872-8081. ; 18:1-4, s. 45-50
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Journal article (peer-reviewed)abstract
- Ubiquinol is a powerful antioxidant, which is oxidized in action and needs to be replaced or regenerated to be capable of a sustained effort. This article summarises current knowledge of extramitochondrial reduction of ubiquinone by three flavoenzymes, i.e. lipoamide dehydrogenase, glutathione reductase and thioredoxin reductase, belonging to the same pyridine nucleotide-disulfide oxidoreductase family. These three enzymes are the most efficient extramitochondrial ubiquinone reductases so far described. The reduction of ubiquinone by lipoamide dehydrogenase and glutathione reductase is potently stimulated by zinc and the highest rate of reduction is achieved at acidic pH and the rates are equal with either NADPH or NADH as co-factors. The most efficient ubiquinone reductases are mammalian cytosolic thioredoxin reductases, which are selenoenzymes with a number of biological functions. Reduction of ubiquinone by thioredoxin reductase is in contrast to the other two enzymes investigated, inhibited by zinc and shows a sharp physiological pH optimum at pH 7.5. Furthermore, the reaction is selenium dependent as revealed from experiments using truncated and mutant forms of the enzyme and also in a cellular context by selenium treatment of transfected thioredoxin reductase overexpressing stable cell lines. The reduction of ubiquinone by the three enzymes offers a multifunctional system for extramitochondrial regeneration of an important antioxidant.
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| 14. |
- Segura-Aguilar, Juan, et al.
(author)
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Astrocytes protect dopaminergic neurons against aminochrome neurotoxicity
- 2022
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In: Neural Regeneration Research. - : Medknow. - 1673-5374 .- 1876-7958. ; 17:9, s. 1861-1866
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Research review (peer-reviewed)abstract
- Astrocytes protect neurons by modulating neuronal function and survival. Astrocytes support neurons in several ways. They provide energy through the astrocyte-neuron lactate shuttle, protect neurons from excitotoxicity, and internalize neuronal lipid droplets to degrade fatty acids for neuronal metabolic and synaptic support, as well as by their high capacity for glutamate uptake and the conversion of glutamate to glutamine. A recent reported astrocyte system for protection of dopamine neurons against the neurotoxic products of dopamine, such as aminochrome and other o-quinones, were generated under neuromelanin synthesis by oxidizing dopamine catechol structure. Astrocytes secrete glutathione transferase M2-2 through exosomes that transport this enzyme into dopaminergic neurons to protect these neurons against aminochrome neurotoxicity. The role of this new astrocyte protective mechanism in Parkinson´s disease is discussed.
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| 15. |
- Segura-Aguilar, Juan, et al.
(author)
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Neuroprotection against Aminochrome Neurotoxicity : Glutathione Transferase M2-2 and DT-Diaphorase
- 2022
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In: Antioxidants. - : MDPI AG. - 2076-3921. ; 11:2
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Journal article (peer-reviewed)abstract
- Glutathione is an important antioxidant that plays a crucial role in the cellular protection against oxidative stress and detoxification of electrophilic mutagens, and carcinogens. Glutathione transferases are enzymes catalyzing glutathione-dependent reactions that lead to inactivation and conjugation of toxic compounds, processes followed by subsequent excretion of the detoxified products. Degeneration and loss of neuromelanin-containing dopaminergic neurons in the nigrostriatal neurons generally involves oxidative stress, neuroinflammation, alpha-synuclein aggregation to neurotoxic oligomers, mitochondrial dysfunction, protein degradation dysfunction, and endoplasmic reticulum stress. However, it is still unclear what triggers these neurodegenerative processes. It has been reported that aminochrome may elicit all of these mechanisms and, interestingly, aminochrome is formed inside neuromelanin-containing dopaminergic neurons during neuromelanin synthesis. Aminochrome is a neurotoxic ortho-quinone formed in neuromelanin synthesis. However, it seems paradoxical that the neurotoxin aminochrome is generated during neuromelanin synthesis, even though healthy seniors have these neurons intact when they die. The explanation of this paradox is the existence of protective tools against aminochrome neurotoxicity composed of the enzymes DT-diaphorase, expressed in these neurons, and glutathione transferase M2-2, expressed in astrocytes. Recently, it has been reported that dopaminergic neurons can be protected by glutathione transferase M2-2 from astrocytes, which secrete exosomes containing the protective enzyme.
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| 16. |
- Sroka, Jolanta, et al.
(author)
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Overexpression of thioredoxin reductase 1 inhibits migration of HEK-293 cells
- 2007
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In: Biology of the Cell. - : John Wiley & Sons. - 0248-4900 .- 1768-322X. ; 99:12, s. 677-687
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Journal article (peer-reviewed)abstract
- BACKGROUND INFORMATION:TrxR (thioredoxin reductase), in addition to protecting against oxidative stress, plays a role in the redox regulation of intracellular signalling pathways controlling, among others, cell proliferation and apoptosis. The aim of the present study was to determine whether TrxR1 is involved in the regulation of cell migration.RESULTS:Stably transfected HEK-293 (human embryonic kidney) cells which overexpress cytosolic TrxR1 (HEK-TrxR15 and HEK-TrxR11 cells) were used in the present study. We found that the stimulation of cell motility induced by PKC (protein kinase C) activators, PMA and DPhT (diphenyltin), was inhibited significantly in the HEK-TrxR15 and HEK-TrxR11 cells compared with control cells. The overexpression of TrxR1 also inhibited characteristic morphological changes and reorganization of the F-actin cytoskeleton induced by PMA and DPhT. In addition, the selective activation of PKCdelta by DPhT was inhibited in cells that overexpressed cytosolic TrxR1. Furthermore, rottlerin, a selective inhibitor of PKCdelta, and PKCdelta siRNA (small interfering RNA), suppressed the morphological changes induced by DPhT in the control cells.CONCLUSIONS:The overexpression of TrxR1 inhibits migration of HEK-293 cells stimulated with PMA and DPhT. Moreover, our observations suggest that this effect is mediated by the inhibition of PKCdelta activation.
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| 17. |
- Valdes, Raúl, et al.
(author)
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Cellular Trafficking of Glutathione Transferase M2-2 Between U373MG and SHSY-S7 Cells is Mediated by Exosomes
- 2021
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In: Neurotoxicity research. - : Springer Science and Business Media LLC. - 1029-8428 .- 1476-3524. ; 39:2, s. 182-190
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Journal article (peer-reviewed)abstract
- The enzyme glutathione transferase M2-2, expressed in human astrocytes, increases its expression in the presence of aminochrome and catalyzes the conjugation of aminochrome, preventing its toxic effects. Secretion of the enzyme glutathione transferase M2-2 from U373MG cells, used as a cellular model for astrocytes, has been reported, and the enzyme is taken up by neuroblastoma SYSH-S7 cells and provide protection against aminochrome. The present study provides evidence that glutathione transferase M2-2 is released in exosomes from U373MG cells, thereby providing a means for intercellular transport of the enzyme. With particular relevance to Parkinson disease and other degenerative conditions, we propose a new mechanism by which astrocytes may protect dopaminergic neurons against the endogenous neurotoxin aminochrome.
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| 18. |
- Xia, Ling, et al.
(author)
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The mammalian cytosolic selenoenzyme thioredoxin reductase reduces ubiquinone. A novel mechanism for defense against oxidative stress
- 2003
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In: Journal of Biological Chemistry. - : American Society for Biochemistry and Molecular Biology. - 0021-9258 .- 1083-351X. ; 278:4, s. 2141-2146
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Journal article (peer-reviewed)abstract
- The selenoprotein thioredoxin reductase (TrxR1) is an essential antioxidant enzyme known to reduce many compounds in addition to thioredoxin, its principle protein substrate. Here we found that TrxR1 reduced ubiquinone-10 and thereby regenerated the antioxidant ubiquinol-10 (Q10), which is important for protection against lipid and protein peroxidation. The reduction was time- and dose-dependent, with an apparent K(m) of 22 microm and a maximal rate of about 12 nmol of reduced Q10 per milligram of TrxR1 per minute. TrxR1 reduced ubiquinone maximally at a physiological pH of 7.5 at similar rates using either NADPH or NADH as cofactors. The reduction of Q10 by mammalian TrxR1 was selenium dependent as revealed by comparison with Escherichia coli TrxR or selenium-deprived mutant and truncated mammalian TrxR forms. In addition, the rate of reduction of ubiquinone was significantly higher in homogenates from human embryo kidney 293 cells stably overexpressing thioredoxin reductase and was induced along with increasing cytosolic TrxR activity after the addition of selenite to the culture medium. These data demonstrate that the selenoenzyme thioredoxin reductase is an important selenium-dependent ubiquinone reductase and can explain how selenium and ubiquinone, by a combined action, may protect the cell from oxidative damage.
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