title: Identification of a selenium-dependent glutathione peroxidase in the blood-sucking insect Rhodnius prolixus.
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.
authors.affiliation: 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.
authors.forename: Felipe A
authors.initials: FA
authors.lastname: Dias
authors.affiliation: 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.
authors.forename: Ana C P
authors.initials: AC
authors.lastname: Gandara
authors.affiliation: 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.
authors.forename: Hugo D
authors.initials: HD
authors.lastname: Perdomo
authors.affiliation: 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.
authors.forename: Renata S
authors.initials: RS
authors.lastname: Gonçalves
authors.affiliation: 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.
authors.forename: Carolina R
authors.initials: CR
authors.lastname: Oliveira
authors.affiliation: Laboratório de Bioquímica de Vetores de Doenças, Departamento de Bioquímica, Instituto de Química, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Raquel L L
authors.initials: RL
authors.lastname: Oliveira
authors.affiliation: Departamento de Nutrição Básica e Experimental, Instituto de Nutrição, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors.forename: Marta
authors.initials: M
authors.lastname: Citelli
authors.affiliation: 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.
authors.forename: Carla R
authors.initials: CR
authors.lastname: Polycarpo
authors.affiliation: Bioinformatics and Genomics Programme, Centre for Genomic Regulation, Dr. Aiguader 88, 08003 Barcelona, Spain; Universitat Pompeu Fabra (UPF), 08003 Barcelona, Spain.
authors.forename: Didac
authors.initials: D
authors.lastname: Santesmasses
authors.affiliation: 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.
authors.forename: Marco
authors.initials: M
authors.lastname: Mariotti
authors.affiliation: Bioinformatics and Genomics Programme, Centre for Genomic Regulation, Dr. Aiguader 88, 08003 Barcelona, Spain.
authors.forename: Roderic
authors.initials: R
authors.lastname: Guigó
authors.affiliation: 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.
authors.forename: Gloria R
authors.initials: GR
authors.lastname: Braz
authors.affiliation: Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Av. IPN 2508, Zacatenco, Mexico City, Mexico.
authors.forename: Fanis
authors.initials: F
authors.lastname: Missirlis
authors.affiliation: 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. Electronic address: pedro@bioqmed.ufrj.br.
authors.forename: Pedro L
authors.initials: PL
authors.lastname: Oliveira
mesh_terms: D000818:Animals; D005260:Female; D005979:Glutathione Peroxidase / Q000737:chemistry* / Q000235:genetics*; D008658:Inactivation, Metabolic / Q000235:genetics; D018978:Molting; D010802:Phylogeny; D034622:RNA Interference; D011817:Rabbits; D012239:Rhodnius / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development; D012643:Selenium / Q000737:chemistry*; D017279:Selenocysteine / Q000737:chemistry
chemical_list: D017279:Selenocysteine; D005979:Glutathione Peroxidase; D012643:Selenium
keywords: Drosophila melanogaster; Insect; Rhodnius prolixus; Selenium-dependent glutathione peroxidase