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| 2. |
- Chasapis, Christos T., et al.
(author)
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Implications of the mitochondrial interactome of mammalian thioredoxin 2 for normal cellular function and disease
- 2019
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In: Free Radical Biology & Medicine. - : Elsevier. - 0891-5849 .- 1873-4596. ; 137, s. 59-73
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Journal article (peer-reviewed)abstract
- Multiple thioredoxin isoforms exist in all living cells. To explore the possible functions of mammalian mitochondrial thioredoxin 2 (Trx2), an interactome of mouse Trx2 was initially created using (i) a monothiol mouse Trx2 species for capturing protein partners from different organs and (ii) yeast two hybrid screens on human liver and rat brain cDNA libraries. The resulting interactome consisted of 195 proteins (Trx2 included) plus the mitochondrial 16S RNA. 48 of these proteins were classified as mitochondrial (MitoCarta2.0 human inventory). In a second step, the mouse interactome was combined with the current four-membered mitochondrial sub-network of human Trx2 (BioGRID) to give a 53-membered human Trx2 mitochondrial interactome (52 interactor proteins plus the mitochondrial 16S RNA). Although thioredoxins are thiol-employing disulfide oxidoreductases, approximately half of the detected interactions were not due to covalent disulfide bonds. This finding reinstates the extended role of thioredoxins as moderators of protein function by specific non-covalent, protein-protein interactions. Analysis of the mitochondrial interactome suggested that human Trx2 was involved potentially in mitochondrial integrity, formation of iron sulfur clusters, detoxification of aldehydes, mitoribosome assembly and protein synthesis, protein folding, ADP ribosylation, amino acid and lipid metabolism, glycolysis, the TCA cycle and the electron transport chain. The oxidoreductase functions of Trx2 were verified by its detected interactions with mitochondrial peroxiredoxins and methionine sulfoxide reductase. Parkinsons disease, triosephosphate isomerase deficiency, combined oxidative phosphorylation deficiency, and lactate dehydrogenase b deficiency are some of the diseases where the proposed mitochondrial network of Trx2 may be implicated.
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| 3. |
- Cunnea, Paula M, et al.
(author)
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ERdj5, an endoplasmic reticulum (ER)-resident protein containing DnaJ and thioredoxin domains, is expressed in secretory cells or following ER stress.
- 2003
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In: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 278:2, s. 1059-66
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Journal article (peer-reviewed)abstract
- A complex array of chaperones and enzymes reside in the endoplasmic reticulum (ER) to assist the folding and assembly of and the disulfide bond formation in nascent secretory proteins. Here we characterize a novel human putative ER co-chaperone (ERdj5) containing domains resembling DnaJ, protein-disulfide isomerase, and thioredoxin domains. Homologs of ERdj5 have been found in Caenorhabditis elegans and Mus musculus. In vitro experiments demonstrated that ERdj5 interacts via its DnaJ domain with BiP in an ATP-dependent manner. ERdj5 is a ubiquitous protein localized in the ER and is particularly abundant in secretory cells. Its transcription is induced during ER stress, suggesting potential roles for ERdj5 in protein folding and translocation across the ER membrane.
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| 4. |
- Damdimopoulos, Anastasios E., et al.
(author)
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An alternative splicing variant of the selenoprotein thioredoxin reductase is a modulator of estrogen signaling
- 2004
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In: Journal of Biological Chemistry. - : American Society for Biochemistry and Molecular Biology. - 0021-9258 .- 1083-351X. ; 279:37, s. 38721-38729
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Journal article (peer-reviewed)abstract
- The selenoprotein thioredoxin reductase (TrxR1) is an integral part of the thioredoxin system. It serves to transfer electrons from NADPH to thioredoxin leading to its reduction. Interestingly, recent work has indicated that thioredoxin reductase can regulate the activity of transcription factors such as p53, hypoxia-inducible factor, and AP-1. Here, we describe that an alternative splicing variant of thioredoxin reductase (TrxR1b) containing an LXXLL peptide motif, is implicated in direct binding to nuclear receptors. In vitro interaction studies revealed direct interaction of the TrxR1b with the estrogen receptors alpha and beta. Confocal microscopy analysis showed nuclear colocalization of the TrxR1b with both estrogen receptor alpha and beta in estradiol-17beta-treated cells. Transcriptional studies demonstrated that TrxR1b can affect estrogen-dependent gene activation differentially at classical estrogen response elements as compared with AP-1 response elements. Based on these results, we propose a model where thioredoxin reductase directly influences the estrogen receptor-coactivator complex assembly on non-classical estrogen response elements such as AP-1. In summary, our results suggest that TrxR1b is an important modulator of estrogen signaling.
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| 5. |
- Damdimopoulos, Anastasios E., et al.
(author)
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Human mitochondrial thioredoxin. Involvement in mitochondrial membrane potential and cell death
- 2002
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In: Journal of Biological Chemistry. - : American Society for Biochemistry and Molecular Biology. - 0021-9258 .- 1083-351X. ; 277:36, s. 33249-33257
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Journal article (peer-reviewed)abstract
- Thioredoxins (Trx) are a class of small multifunctional redox-active proteins found in all organisms. Recently, we reported the cloning of a mitochondrial thioredoxin, Trx2, from rat heart. To investigate the biological role of Trx2 we have isolated the human homologue, hTrx2, and generated HEK-293 cells overexpressing Trx2 (HEK-Trx2). Here, we show that HEK-Trx2 cells are more resistant toward etoposide. In addition, HEK-Trx2 are more sensitive toward rotenone, an inhibitor of complex I of the respiratory chain. Finally, overexpression of Trx2 confers an increase in mitochondrial membrane potential, DeltaPsi(m). Treatment with oligomycin could both reverse the effect of rotenone and decrease the membrane potential suggesting that Trx2 interferes with the activity of ATP synthase. Taken together, these results suggest that Trx2 interacts with specific components of the mitochondrial respiratory chain and plays an important role in the regulation of the mitochondrial membrane potential.
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| 6. |
- Jiménez, Alberto, et al.
(author)
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Cloning, expression and characterization of mouse spermatid specific thioredoxin-1 gene and protein
- 2002
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In: Molecular human reproduction. - : Oxford University Press. - 1360-9947 .- 1460-2407. ; 8:8, s. 710-718
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Journal article (peer-reviewed)abstract
- Thioredoxins are proteins that participate in different cellular processes via redox-mediated reactions. For humans, we have recently described two novel members of this family that display a male germ cell specific expression pattern, named spermatid specific thioredoxin (Sptrx-1 and Sptrx-2 respectively). We report here the cloning and characterization of the mouse Sptrx-1 gene and protein, which are similar to those described for the human orthologue. The mouse Sptrx-1 open reading frame encodes for a protein of 462 aa composed of an N-terminal repetitive domain of a 15 residue motif followed by a C-terminal domain typical of thioredoxins. The mouse Sptrx-1 gene sequence is interrupted by only one intron of 525 bp located in the 5'-UTR, and using fluorescence in-situ hybridization we have mapped its chromosomal location to 17E1.2-1.3. Northern blot analysis identified the testis as the only tissue expressing mouse Sptrx-1 mRNA, and by in-situ hybridization we found a strong labelling in the testicular seminiferous tubules, mostly in the round spermatids. Affinity purified antibodies against human Sptrx-1 crossreacted well with the mouse protein confirming its expression in seminiferous tubules at the later stages of spermiogenesis. Recombinant mouse Sptrx-1 displayed protein disulphide reducing activity in an enzymatic assay coupled to NADPH and thioredoxin reductase. The availability of the mouse Sptrx-1 gene sequence is the first step towards the generation of knock-out mice, whose characterization will provide significant information regarding the in-vivo function of Sptrx-1 and its possible implication in several sperm anomalies.
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| 7. |
- Miranda-Vizuete, Antonio, et al.
(author)
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cDNA cloning, expression and chromosomal localization of the mouse mitochondrial thioredoxin reductase gene(1)
- 1999
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In: Biochimica et Biophysica Acta. - : Elsevier. - 0006-3002 .- 1878-2434. ; 1447:1, s. 113-118
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Journal article (peer-reviewed)abstract
- Cytosolic thioredoxin (Trx) and thioredoxin reductase (TrxR) comprise a ubiquitous system that uses the reducing power of NADPH to act as a general disulfide reductase system as well as a potent antioxidant system. Human and rat mitochondria contain a complete thioredoxin system different from the one present in the cytosol. The mitochondrial system is involved in the oxidative stress protection through a mitochondrial thioredoxin-dependent peroxidase. We report here the cDNA cloning and chromosomal localization of the mouse mitochondrial thioredoxin reductase gene (TrxR2). The mouse TrxR2 cDNA encodes for a putative protein of 527 amino acid residues with a calculated molecular mass of 57 kDa, that displays high homology with the human and rat counterparts. The N-terminus of the protein displays typical features of a mitochondrial targeting sequence with absence of acidic residues and abundance of basic residues. Mouse TrxR2 also contains a stop codon in frame at the C-terminus of the protein, necessary for the incorporation of selenocysteine that is required for enzymatic activity. The typical stem-loop structure (SECIS element) that drives the incorporation of selenocysteine is identified in the 3'-UTR. Northern analysis of the mouse TrxR2 mRNA shows a similar pattern of expression with the human homologue, with higher expression in liver, heart and kidney. Finally, we have assigned the mouse TrxR2 gene to chromosome 16 mapping at 11.2 cM from the centromer and linked to the catechol-o-methyltransferase (comt) gene.
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| 8. |
- Miranda-Vizuete, Antonio, et al.
(author)
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Characterization of Sptrx, a novel member of the thioredoxin family specifically expressed in human spermatozoa
- 2001
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In: Journal of Biological Chemistry. - : American Society for Biochemistry and Molecular Biology. - 0021-9258 .- 1083-351X. ; 276:34, s. 31567-31574
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Journal article (peer-reviewed)abstract
- Thioredoxins (Trx) are small ubiquitous proteins that participate in different cellular processes via redox-mediated reactions. We report here the identification and characterization of a novel member of the thioredoxin family in humans, named Sptrx (sperm-specific trx), the first with a tissue-specific distribution, located exclusively in spermatozoa. Sptrx open reading frame encodes for a protein of 486 amino acids composed of two clear domains: an N-terminal domain consisting of 23 highly conserved repetitions of a 15-residue motif and a C-terminal domain typical of thioredoxins. Northern analysis and in situ hybridization shows that Sptrx mRNA is only expressed in human testis, specifically in round and elongating spermatids. Immunostaining of human testis sections identified Sptrx protein in spermatids, while immunofluorescence and immunogold electron microscopy analysis demonstrated Sptrx localization in the cytoplasmic droplet of ejaculated sperm. Sptrx appears to have a multimeric structure in native conditions and is able to reduce insulin disulfide bonds in the presence of NADPH and thioredoxin reductase. During mammalian spermiogenesis in testis seminiferous tubules and later maturation in epididymis, extensive reorganization of disulfide bonds is required to stabilize cytoskeletal sperm structures. However, the molecular mechanisms that control these processes are not known. The identification of Sptrx with an expression pattern restricted to the postmeiotic phase of spermatogenesis, when the sperm tail is organized, suggests that Sptrx might be an important factor in regulating critical steps of human spermiogenesis.
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| 9. |
- Miranda-Vizuete, Antonio, et al.
(author)
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Genomic structure and chromosomal localization of human thioredoxin-like protein gene (txl)
- 2000
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In: Mitochondrial DNA. - : Informa Healthcare. - 1940-1736 .- 1940-1744. ; 10:6, s. 419-424
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Journal article (peer-reviewed)abstract
- Human thioredoxin-like protein (txl) is a novel member of the expanding thioredoxin superfamily whose main characteristic is the presence, after the thioredoxin domain, of a C-terminal extension of 184 residues with no homology with any other protein in the databases. Txl is a cytosolic ubiquitously expressed protein and it has been copurified with a kinase of the STE20 family, which is proteolytically activated by caspases in apoptosis. However, no cellular function has yet been assigned to this protein. In the present study we report the genomic organization of the txl gene which encompasses approximately 36 kb organized in eight exons ranging from 96 bp to 303 bp. In contrast, intron sizes are much bigger ranging from 1.5 kb to 12 kb. Chromosomal localization of txl gene revealed that it maps at position 18q21, a region frequently affected in different human tumours. Furthermore, we have identified the putative homologues of txl in both Drosophila melanogaster and Caenorhabditis elegans that display much closer homology to the known thioredoxins than the human txl protein. Indeed, critical residues for optimal thioredoxin activity are present in both Drosophila and Caenorhabditis txl but absent in the human protein suggesting that txl might have evolved to carry out a function different from the general disulfide reductase typical of thioredoxins.
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| 10. |
- Miranda-Vizuete, Antonio, et al.
(author)
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Identification of a novel thioredoxin-1 pseudogene on human chromosome 10
- 2000
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In: Mitochondrial DNA. - : Informa Healthcare. - 1940-1736 .- 1940-1744. ; 10:6, s. 411-414
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Journal article (peer-reviewed)abstract
- Thioredoxin (Trx) is a small, ubiquitous protein of 12 kDa that acts as general dithiol-disulfide oxidoreductase via its conserved redox active site Trp-Cys-Gly-Pro-Cys which is located in a protrusion of the protein (Holmgren 1985). Mammalian cells contain two forms of thioredoxin: Trx1, a cytosolic enzyme able to translocate to the nucleus under certain stimuli and be secreted from the cells thus displaying cytokine-like properties and Trx2, a mitochondrial enzyme (Tagaya et al. 1989; Spyrou et al 1997). While many functions have been described for Trx1 for example antioxidant enzyme, modulator of transcription factors, electron donor for enzymes like ribonucleotide reductase and PAPS reductase, etc. (see introduction Spyrou et al. 1997), only an antioxidant function has been assigned to Trx2. Trx2 acts as a reductant of a mitochondrial thioredoxin-dependent peroxidase which protects cells against hydrogen peroxide treatment (Araki et al. 1999). Human Trx1 gene maps at chromosome 9q31 and several bands hybridize with a Trx1 probe in Southern blots suggesting the existence of Trx1 derived sequences in the human genome (Heppell-Parton et al. 1995; Kaghad et al. 1994). As only one active Trx1 gene has been described, the other hybridizing bands might correspond to different inactive pseudogenes (Kaghad et al. 1994), but only one Trx1 pseudogene has been described so far (GenBank accession number: AF146023 (Tonissen and Wells 1991)). We report here the sequence of a second Trx1 retrotranscribed pseudogene and propose the nomenclature wTrx1-1 and wTrx1-2.
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