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Madhwani KR, Sayied S, Ogata CH, Hogan CA, Lentini JM, Mallik M, Dumouchel JL, Storkebaum E, Fu D, O’Connor-Giles KM. tRNA modification enzyme-dependent redox homeostasis regulates synapse formation and memory. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.14.566895. [PMID: 38014328 PMCID: PMC10680711 DOI: 10.1101/2023.11.14.566895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Post-transcriptional modification of RNA regulates gene expression at multiple levels. ALKBH8 is a tRNA modifying enzyme that methylates wobble uridines in specific tRNAs to modulate translation. Through methylation of tRNA-selenocysteine, ALKBH8 promotes selenoprotein synthesis and regulates redox homeostasis. Pathogenic variants in ALKBH8 have been linked to intellectual disability disorders in the human population, but the role of ALKBH8 in the nervous system is unknown. Through in vivo studies in Drosophila, we show that ALKBH8 controls oxidative stress in the brain to restrain synaptic growth and support learning and memory. ALKBH8 null animals lack wobble uridine methylation and exhibit a global reduction in protein synthesis, including a specific decrease in selenoprotein levels. Loss of ALKBH8 or independent disruption of selenoprotein synthesis results in ectopic synapse formation. Genetic expression of antioxidant enzymes fully suppresses synaptic overgrowth in ALKBH8 null animals, confirming oxidative stress as the underlying cause of dysregulation. ALKBH8 animals also exhibit associative learning and memory impairments that are reversed by pharmacological antioxidant treatment. Together, these findings demonstrate the critical role of tRNA modification in redox homeostasis in the nervous system and reveal antioxidants as a potential therapy for ALKBH8-associated intellectual disability.
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Affiliation(s)
| | - Shanzeh Sayied
- Department of Neuroscience, Brown University, Providence, RI, USA
| | | | - Caley A. Hogan
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI, USA
| | - Jenna M. Lentini
- Department of Biology, Center for RNA Biology, University of Rochester, Rochester, NY, USA
| | - Moushami Mallik
- Molecular Neurobiology Laboratory, Donders Institute for Brain, Cognition, and Behaviour, Radboud University, Nijmegen, NL
| | | | - Erik Storkebaum
- Molecular Neurobiology Laboratory, Donders Institute for Brain, Cognition, and Behaviour, Radboud University, Nijmegen, NL
| | - Dragony Fu
- Department of Biology, Center for RNA Biology, University of Rochester, Rochester, NY, USA
| | - Kate M. O’Connor-Giles
- Department of Neuroscience, Brown University, Providence, RI, USA
- Carney Institute for Brain Sciences, Brown University, Providence, RI, USA
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2
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Serrão VHB, Silva IR, da Silva MTA, Scortecci JF, de Freitas Fernandes A, Thiemann OH. The unique tRNASec and its role in selenocysteine biosynthesis. Amino Acids 2018; 50:1145-1167. [DOI: 10.1007/s00726-018-2595-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Accepted: 05/26/2018] [Indexed: 12/26/2022]
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3
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Dias FA, Gandara ACP, Perdomo HD, Gonçalves RS, Oliveira CR, Oliveira RLL, Citelli M, Polycarpo CR, Santesmasses D, Mariotti M, Guigó R, Braz GR, Missirlis F, Oliveira PL. Identification of a selenium-dependent glutathione peroxidase in the blood-sucking insect Rhodnius prolixus. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2016; 69:105-114. [PMID: 26392061 DOI: 10.1016/j.ibmb.2015.08.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Revised: 08/27/2015] [Accepted: 08/31/2015] [Indexed: 06/05/2023]
Abstract
The selenium-dependent glutathione peroxidase (SeGPx) is a well-studied enzyme that detoxifies organic and hydrogen peroxides and provides cells or extracellular fluids with a key antioxidant function. The presence of a SeGPx has not been unequivocally demonstrated in insects. In the present work, we identified the gene and studied the function of a Rhodnius prolixus SeGPx (RpSeGPx). The RpSeGPx mRNA presents the UGA codon that encodes the active site selenocysteine (Sec) and a corresponding Sec insertion sequence (SECIS) in the 3' UTR region. The encoded protein includes a signal peptide, which is consistent with the high levels of GPx enzymatic activity in the insect's hemolymph, and clusters phylogenetically with the extracellular mammalian GPx03. This result contrasts with all other known insect GPxs, which use a cysteine residue instead of Sec and cluster with the mammalian phospholipid hydroperoxide GPx04. RpSeGPx is widely expressed in insect organs, with higher expression levels in the fat body. RNA interference (RNAi) was used to reduce RpSeGPx gene expression and GPx activity in the hemolymph. Adult females were apparently unaffected by RpSeGPx RNAi, whereas first instar nymphs showed a three-day delay in ecdysis. Silencing of RpSeGPx did not alter the gene expression of the antioxidant enzymes catalase, xanthine dehydrogenase and a cysteine-GPx, but it reduced the levels of the dual oxidase and NADPH oxidase 5 transcripts that encode for enzymes releasing extracellular hydrogen peroxide/superoxide. Collectively, our data suggest that RpSeGPx functions in the regulation of extracellular (hemolymph) redox homeostasis of R. prolixus.
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Affiliation(s)
- Felipe A Dias
- Laboratório de Bioquímica de Artrópodes Hematófagos, Instituto de Bioquímica Médica, Programa de Biologia Molecular e Biotecnologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Ana C P Gandara
- Laboratório de Bioquímica de Artrópodes Hematófagos, Instituto de Bioquímica Médica, Programa de Biologia Molecular e Biotecnologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Hugo D Perdomo
- Laboratório de Bioquímica de Artrópodes Hematófagos, Instituto de Bioquímica Médica, Programa de Biologia Molecular e Biotecnologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Renata S Gonçalves
- Laboratório de Bioquímica de Artrópodes Hematófagos, Instituto de Bioquímica Médica, Programa de Biologia Molecular e Biotecnologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Carolina R Oliveira
- Laboratório de Bioquímica de Artrópodes Hematófagos, Instituto de Bioquímica Médica, Programa de Biologia Molecular e Biotecnologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Raquel L L Oliveira
- Laboratório de Bioquímica de Vetores de Doenças, Departamento de Bioquímica, Instituto de Química, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Marta Citelli
- Departamento de Nutrição Básica e Experimental, Instituto de Nutrição, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Carla R Polycarpo
- Laboratório de Bioquímica de Artrópodes Hematófagos, Instituto de Bioquímica Médica, Programa de Biologia Molecular e Biotecnologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil; Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular (INCT-EM), Brazil
| | - Didac Santesmasses
- Bioinformatics and Genomics Programme, Centre for Genomic Regulation, Dr. Aiguader 88, 08003 Barcelona, Spain; Universitat Pompeu Fabra (UPF), 08003 Barcelona, Spain
| | - Marco Mariotti
- Bioinformatics and Genomics Programme, Centre for Genomic Regulation, Dr. Aiguader 88, 08003 Barcelona, Spain; Department of Medicine, Division of Genetics, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Roderic Guigó
- Bioinformatics and Genomics Programme, Centre for Genomic Regulation, Dr. Aiguader 88, 08003 Barcelona, Spain
| | - Gloria R Braz
- Laboratório de Bioquímica de Vetores de Doenças, Departamento de Bioquímica, Instituto de Química, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil; Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular (INCT-EM), Brazil
| | - Fanis Missirlis
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Av. IPN 2508, Zacatenco, Mexico City, Mexico
| | - Pedro L Oliveira
- Laboratório de Bioquímica de Artrópodes Hematófagos, Instituto de Bioquímica Médica, Programa de Biologia Molecular e Biotecnologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil; Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular (INCT-EM), Brazil.
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4
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Abstract
Recent identification of new selenocysteine-containing proteins has revealed relationships between the two trace elements selenium (Se) and iodine and the hormone network. Several selenoproteins participate in the protection of thyrocytes from damage by H(2)O(2) produced for thyroid hormone biosynthesis. Iodothyronine deiodinases are selenoproteins contributing to systemic or local thyroid hormone homeostasis. The Se content in endocrine tissues (thyroid, adrenals, pituitary, testes, ovary) is higher than in many other organs. Nutritional Se depletion results in retention, whereas Se repletion is followed by a rapid accumulation of Se in endocrine tissues, reproductive organs, and the brain. Selenoproteins such as thioredoxin reductases constitute the link between the Se metabolism and the regulation of transcription by redox sensitive ligand-modulated nuclear hormone receptors. Hormones and growth factors regulate the expression of selenoproteins and, conversely, Se supply modulates hormone actions. Selenoproteins are involved in bone metabolism as well as functions of the endocrine pancreas and adrenal glands. Furthermore, spermatogenesis depends on adequate Se supply, whereas Se excess may impair ovarian function. Comparative analysis of the genomes of several life forms reveals that higher mammals contain a limited number of identical genes encoding newly detected selenocysteine-containing proteins.
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Affiliation(s)
- J Köhrle
- Institut für Experimentelle Endokrinologie, Charité, Humboldt Universität zu Berlin, Schumannstrasse 20/21, D-10098 Berlin, Germany.
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Jameson RR, Diamond AM. A regulatory role for Sec tRNA[Ser]Sec in selenoprotein synthesis. RNA (NEW YORK, N.Y.) 2004; 10:1142-1152. [PMID: 15208449 PMCID: PMC1370604 DOI: 10.1261/rna.7370104] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2004] [Accepted: 04/20/2004] [Indexed: 05/24/2023]
Abstract
Selenium is biologically active through the functions of selenoproteins that contain the amino acid selenocysteine. This amino acid is translated in response to in-frame UGA codons in mRNAs that include a SECIS element in its 3' untranslated region, and this process requires a unique tRNA, referred to as tRNA([Ser]Sec). The translation of UGA as selenocysteine, rather than its use as a termination signal, is a candidate restriction point for the regulation of selenoprotein synthesis by selenium. A specialized reporter construct was used that permits the evaluation of SECIS-directed UGA translation to examine mechanisms of the regulation of selenoprotein translation. Using SECIS elements from five different selenoprotein mRNAs, UGA translation was quantified in response to selenium supplementation and alterations in tRNA([Ser]Sec) levels and isoform distributions. Although each of the evaluated SECIS elements exhibited differences in their baseline activities, each was stimulated to a similar extent by increased selenium or tRNA([Ser]Sec) levels and was inhibited by diminished levels of the methylated isoform of tRNA([Ser]Sec) achieved using a dominant-negative acting mutant tRNA([Ser]Sec). tRNA([Ser]Sec) was found to be limiting for UGA translation under conditions of high selenoprotein mRNA in both a transient reporter assay and in cells with elevated GPx-1 mRNA. This and data indicating increased amounts of the methylated isoform of tRNA([Ser]Sec) during selenoprotein translation indicate that it is this isoform that is translationally active and that selenium-induced tRNA methylation is a mechanism of regulation of the synthesis of selenoproteins.
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Affiliation(s)
- Ruth R Jameson
- Department of Human Nutrition, University of Illinois at Chicago, 1919 West Taylor Street, MC517, Chicago, IL 60612, USA
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6
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Rao M, Carlson BA, Novoselov SV, Weeks DP, Gladyshev VN, Hatfield DL. Chlamydomonas reinhardtii selenocysteine tRNA[Ser]Sec. RNA (NEW YORK, N.Y.) 2003; 9:923-30. [PMID: 12869703 PMCID: PMC1370458 DOI: 10.1261/rna.5510503] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2003] [Accepted: 05/07/2003] [Indexed: 05/19/2023]
Abstract
Eukaryotic selenocysteine (Sec) protein insertion machinery was thought to be restricted to animals, but the occurrence of both Sec-containing proteins and the Sec insertion system was recently found in Chlamydomonas reinhardtii, a member of the plant kingdom. Herein, we used RT-PCR to determine the sequence of C. reinhardtii Sec tRNA[Ser]Sec, the first non-animal eukaryotic Sec tRNA[Ser]Sec sequence. Like its animal counterpart, it is 90 nucleotides in length, is aminoacylated with serine by seryl-tRNA synthetase, and decodes specifically UGA. Evolutionary analyses of known Sec tRNAs identify the C. reinhardtii form as the most diverged eukaryotic Sec tRNA[Ser]Sec and reveal a common origin for this tRNA in bacteria, archaea, and eukaryotes.
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Affiliation(s)
- Mahadev Rao
- Section on the Molecular Biology of Selenium, Basic Research Laboratory, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
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7
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MESH Headings
- Animals
- Base Sequence
- Cattle
- Chromatography, Liquid
- Escherichia coli/genetics
- Escherichia coli/metabolism
- Gene Expression
- HL-60 Cells
- Humans
- In Vitro Techniques
- Liver/metabolism
- Models, Molecular
- Molecular Sequence Data
- Nucleic Acid Conformation
- Protein Biosynthesis
- Proteins/genetics
- RNA, Bacterial/chemistry
- RNA, Bacterial/genetics
- RNA, Transfer, Amino Acid-Specific/chemistry
- RNA, Transfer, Amino Acid-Specific/genetics
- RNA, Transfer, Amino Acid-Specific/isolation & purification
- Selenocysteine/genetics
- Selenocysteine/metabolism
- Selenoproteins
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Affiliation(s)
- Bradley A Carlson
- Section on Molecular Biology of Selenium, Basic Research Laboratory, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
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8
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Morey M, Serras F, Baguñà J, Hafen E, Corominas M. Modulation of the Ras/MAPK signalling pathway by the redox function of selenoproteins in Drosophila melanogaster. Dev Biol 2001; 238:145-56. [PMID: 11784000 DOI: 10.1006/dbio.2001.0389] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Modulation of reactive oxygen species (ROS) plays a key role in signal transduction pathways. Selenoproteins act controlling the redox balance of the cell. We have studied how the alteration of the redox balance caused by patufet (selD(ptuf)), a null mutation in the Drosophila melanogaster selenophosphate synthetase 1 (sps1) gene, which codes for the SelD enzyme of the selenoprotein biosynthesis, affects the Ras/MAPK signalling pathway. The selD(ptuf) mutation dominantly suppresses the phenotypes in the eye and the wing caused by hyperactivation of the Ras/MAPK cassette and the activated forms of the Drosophila EGF receptor (DER) and Sevenless (Sev) receptor tyrosine kinases (RTKs), which signal in the eye and wing, respectively. No dominant interaction is observed with sensitized conditions in the Wnt, Notch, Insulin-Pi3K, and DPP signalling pathways. Our current hypothesis is that selenoproteins selectively modulate the Ras/MAPK signalling pathway through their antioxidant function. This is further supported by the fact that a selenoprotein-independent increase in ROS caused by the catalase amorphic Cat(n1) allele also reduces Ras/MAPK signalling. Here, we present the first evidence for the role of intracellular redox environment in signalling pathways in Drosophila as a whole organism.
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Affiliation(s)
- M Morey
- Departament de Genètica, Facultat de Biologia, Universitat de Barcelona, Diagonal 645, Barcelona, 08028, Spain
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9
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Castellano S, Morozova N, Morey M, Berry MJ, Serras F, Corominas M, Guigó R. In silico identification of novel selenoproteins in the Drosophila melanogaster genome. EMBO Rep 2001; 2:697-702. [PMID: 11493597 PMCID: PMC1083988 DOI: 10.1093/embo-reports/kve151] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
In selenoproteins, incorporation of the amino acid selenocysteine is specified by the UGA codon, usually a stop signal. The alternative decoding of UGA is conferred by an mRNA structure, the SECIS element, located in the 3'-untranslated region of the selenoprotein mRNA. Because of the non-standard use of the UGA codon, current computational gene prediction methods are unable to identify selenoproteins in the sequence of the eukaryotic genomes. Here we describe a method to predict selenoproteins in genomic sequences, which relies on the prediction of SECIS elements in coordination with the prediction of genes in which the strong codon bias characteristic of protein coding regions extends beyond a TGA codon interrupting the open reading frame. We applied the method to the Drosophila melanogaster genome, and predicted four potential selenoprotein genes. One of them belongs to a known family of selenoproteins, and we have tested experimentally two other predictions with positive results. Finally, we have characterized the expression pattern of these two novel selenoprotein genes.
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Affiliation(s)
- S Castellano
- Grup de Recerca en Informàtica Biomèdica, Institut Municipal d'Investigació Mèdica, Universitat Pompeu Fabra, Dr. Aiguader 80, 08003 Barcelona, Spain
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10
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Martin-Romero FJ, Kryukov GV, Lobanov AV, Carlson BA, Lee BJ, Gladyshev VN, Hatfield DL. Selenium metabolism in Drosophila: selenoproteins, selenoprotein mRNA expression, fertility, and mortality. J Biol Chem 2001; 276:29798-804. [PMID: 11389138 DOI: 10.1074/jbc.m100422200] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Selenocysteine is a rare amino acid in protein that is encoded by UGA with the requirement of a downstream mRNA stem-loop structure, the selenocysteine insertion sequence element. To detect selenoproteins in Drosophila, the entire genome was analyzed with a novel program that searches for selenocysteine insertion sequence elements, followed by selenoprotein gene signature analyses. This computational screen and subsequent metabolic labeling with (75)Se and characterization of selenoprotein mRNA expression resulted in identification of three selenoproteins: selenophosphate synthetase 2 and novel G-rich and BthD selenoproteins that had no homology to known proteins. To assess a biological role for these proteins, a simple chemically defined medium that supports growth of adult Drosophila and requires selenium supplementation for optimal survival was devised. Flies survived on this medium supplemented with 10(-8) to 10(-6) m selenium or on the commonly used yeast-based complete medium at about twice the rate as those on a medium without selenium or with >10(-6) m selenium. This effect correlated with changes in selenoprotein mRNA expression. The number of eggs laid by Drosophila was reduced approximately in half in the chemically defined medium compared with the same medium supplemented with selenium. The data provide evidence that dietary selenium deficiency shortens, while supplementation of the diet with selenium normalizes the Drosophila life span by a process that may involve the newly identified selenoproteins.
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Affiliation(s)
- F J Martin-Romero
- Section on the Molecular Biology of Selenium, Basic Research Laboratory, NCI, National Institutes of Health, Bethesda, Maryland 20892, USA
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