RESUMO
Taenia solium can cause human taeniasis and/or cysticercosis. The latter can in some instances cause human neurocysticercosis which is considered a priority in disease-control strategies and the prevention of mental health problems. Glutathione transferases are crucial for the establishment and long-term survival of T. solium; therefore, we structurally analyzed the 24-kDa glutathione transferase gene (Ts24gst) of T. solium and biochemically characterized its product. The gene promoter showed potential binding sites for transcription factors and xenobiotic regulatory elements. The gene consists of a transcription start site, four exons split by three introns, and a polyadenylation site. The gene architecture is conserved in cestodes. Recombinant Ts24GST (rTs24GST) was active and dimeric. Anti-rTs24GST serum showed slight cross-reactivity with human sigma-class GST. A 3D model of Ts24GST enabled identification of putative residues involved in interactions of the G-site with GSH and of the H-site with CDNB and prostaglandin D2. Furthermore, rTs24GST showed optimal activity at 45 °C and pH 9, as well as high structural stability in a wide range of temperatures and pHs. These results contribute to the better understanding of this parasite and the efforts directed to fight taeniasis/cysticercosis.
Assuntos
Glutationa Transferase , Taenia solium , Taenia solium/genética , Taenia solium/enzimologia , Animais , Glutationa Transferase/genética , Glutationa Transferase/metabolismo , Glutationa Transferase/química , Humanos , Modelos Moleculares , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Proteínas Recombinantes/química , Regiões Promotoras Genéticas/genéticaRESUMO
Glutathione transferase enzymes (GSTs) are believed to be a major detoxification system in helminth parasites and have been associated with immunomodulation of the host response. Echinococcus granulosus sensu lato (s.l.) is a cestode parasite known to express at least five different GSTs, but no Omega-class enzymes have been reported in this parasite or in any other cestode. Herein we report the identification of a new member of the GST superfamily in E. granulosus s.l., which is phylogenetically related to the Omega-class: EgrGSTO. Through mass spectrometry, we showed that the 237 amino acids protein EgrGSTO is expressed by the parasite. Moreover, we identified homologues of EgrGSTO in other eight members of the Taeniidae family, including E. canadensis, E. multilocularis, E. oligarthrus, Hydatigera taeniaeformis, Taenia asiatica, T. multiceps, T. saginata and T. solium. A manual sequence inspection and rational modification yielded eight Taeniidae's GSTO sequences, each one encoding for a 237 aa polypeptide showing 80.2% overall identity. To the best of our knowledge, this is the first description of genes encoding for Omega-class GSTs in worms belonging to the Taeniidae family -that at least in E. granulosus s.l. is expressed as a protein- suggesting the gene encodes for a functional protein.
Assuntos
Echinococcus granulosus , Parasitos , Taenia , Animais , Glutationa Transferase/química , Echinococcus granulosus/genética , Parasitos/metabolismoRESUMO
Investigations of the effect of antioxidants on idiopathic Parkinson's disease have been unsuccessful because the preclinical models used to propose these clinical studies do not accurately represent the neurodegenerative process of the disease. Treatment with certain exogenous neurotoxins induces massive and extremely rapid degeneration; for example, MPTP causes severe Parkinsonism in just three days, while the degenerative process of idiopathic Parkinson´s disease proceeds over many years. The endogenous neurotoxin aminochrome seems to be a good alternative target since it is formed in the nigrostriatal system neurons where the degenerative process occurs. Aminochrome induces all the mechanisms reported to be involved in the degenerative processes of idiopathic Parkinson's disease. The presence of neuromelanin-containing dopaminergic neurons in the postmortem brain of healthy elderly people suggests that neuromelanin synthesis is a normal and harmless process despite the fact that it requires oxidation of dopamine to three ortho-quinones that are potentially toxic, especially aminochrome. The apparent contradiction that neuromelanin synthesis is harmless, despite its formation via neurotoxic ortho-quinones, can be explained by the protective roles of DT-diaphorase and glutathione transferase GSTM2-2 as well as the neuroprotective role of astrocytes secreting exosomes loaded with GSTM2-2. Increasing the expression of DT-diaphorase and GSTM2-2 may be a therapeutic goal to prevent the degeneration of new neuromelanin-containing dopaminergic neurons. Several phytochemicals that induce DT-diaphorase have been discovered and, therefore, an interesting question is whether these phytochemical KEAP1/NRF2 activators can inhibit or decrease aminochrome-induced neurotoxicity.
RESUMO
Glutathione transferases (GSTs) perform catalytic and non-catalytic activities, mostly involved in stress-response and cell detoxification. Helminth parasites express several GSTs of multiple classes that are involved in the neutralization of potentially harmful oxidants, and in the inactivation or removal of xenobiotics. Additionally, GSTs participate in immunomodulatory processes that facilitate the parasite establishment and survival within its host. In Echinococcus granulosus sensu lato (s.l.) -the cestode parasite responsible for cystic echinococcosis- only one Mu-class GST has been reported. In the present work, by using bioinformatic and proteomic approaches we searched for novel Mu-class GSTs potentially involved in the parasite oxidative-stress metabolism. In the genome of E. granulosus s.l., 6 GST-related sequences were found to constitute a strongly conserved phylogenetical clade with Mu-class members. Among them, 5 displayed conserved gene structure (exon/intron), as well as specific residues and motifs characteristic of Mu-class enzymes. By proteomic analysis, 3 Mu-GSTs were identified to be expressed in the protoscolex parasite stage, 2 of them being firstly described as Mu-class GSTs here. The existence of more than one productive Mu-GST gene expands the parasite xenobiotic phase II metabolism, which might have beneficial roles on E. granulosus s.l. ability to successfully infect its host.
Assuntos
Equinococose , Echinococcus granulosus , Parasitos , Animais , Equinococose/parasitologia , Echinococcus granulosus/genética , Glutationa Transferase/genética , Glutationa Transferase/metabolismo , Parasitos/metabolismo , ProteômicaRESUMO
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.
RESUMO
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.
RESUMO
Neurocysticercosis caused by Taenia solium larvae is a neglected disease that persists in several countries, including Mexico, and causes a high disability-adjusted life year burden. Neuroimaging tools such as computed tomography and magnetic resonance imaging are the most efficient for its detection, but low availability and high costs in most endemic regions limit their use. Serological methods such as lentil lectin-purified glycoprotein enzyme-linked immunoelectrotransfer blot antibody detection and monoclonal antibody-based enzyme-linked immunosorbent assays for HP10 antigen detection have been useful in supporting the diagnosis of this disease. We evaluated three T. solium recombinant antigens: glutathione transferase of 26 kDa (Ts26GST); thioredoxin-1 (TsTrx-1), and endophilin B1 (TsMEndoB1) by EITB. These are antigenic proteins antigenic, abundant in excretion/secretion products of the parasite, and do not cross-react with homologous host proteins. Ts26GST and TsTrx-1 showed sensitivity of 79 and 88%, specificity of 86 and 97%, PPV of 83 and 97% and NPV of 82 and 91%, respectively, for neurocysticercosis diagnosis. The recombinant antigens allowed the diagnosis of 70% (Ts26GST) and 80% (TsTrx-1) of patients having only one cysticercus. Further studies on specific regions of these proteins could improve T. solium diagnostics.
Assuntos
Neurocisticercose , Taenia solium , Animais , Anticorpos Anti-Helmínticos , Antígenos de Helmintos/genética , Ensaio de Imunoadsorção Enzimática/métodos , Glutationa Transferase/genética , Humanos , Neurocisticercose/diagnóstico , Neurocisticercose/parasitologia , Sensibilidade e Especificidade , Taenia solium/genética , Tiorredoxinas/genéticaRESUMO
Human Papillomavirus (HPV) is the most important risk factor for cervical cancer, although not the only one. The allelic polymorphism of enzymes acting on carcinogen metabolism has shown to influence the risk of both intraepithelial lesions and cervical carcinogenesis. Several studies found an association between GSTM1/GSTT1 null genotypes and risk of cancer. This research aimed to review studies addressing the relationship between GSTT1 and GSTM1 and HPV infection in women, with or without cervical pathologies. A database search was conducted in four databases - PubMed, LILACS, SciELO, and Virtual Health Library - using the following descriptors: Glutathione transferase, HPV, and Genetic polymorphism. In total, we found 319 studies. After screening titles and abstracts, 27 articles were selected for full-text read, among which 20 were excluded and 7 were included in the review. No study has exclusively approached the relationship between the virus and GSTM1/GSTT1 variants. However, studies investigating the association between single nucleotide polymorphisms (SNPs) and cervical lesions or cancer found a probable relationship between them and infections with high-risk oncogenic subtypes. Although inconclusive, GSTT1 null alleles were more common in women with more aggressive HPV than GSTM1.
Assuntos
Glutationa Transferase/genética , Papillomaviridae , Infecções por Papillomavirus/genética , Polimorfismo de Nucleotídeo Único , Alelos , Feminino , Predisposição Genética para Doença/genética , Humanos , Infecções por Papillomavirus/complicações , Infecções por Papillomavirus/virologia , Fatores de Risco , Neoplasias do Colo do Útero/epidemiologia , Neoplasias do Colo do Útero/etiologia , Neoplasias do Colo do Útero/genéticaRESUMO
Insect diapause shares many biochemical features with other states of metabolic depression, including the suppression of global metabolism, reorganization of metabolic pathways and improved stress resistance. However, little is known about the biochemical changes associated with the diapause phenotype in tropical insects. To investigate biochemical adaptations associated with tropical diapause, we measured the activities of metabolic and antioxidant enzymes, as well as glutathione levels, in the sunflower caterpillar Chlosyne lacinia at different times after initiation of diapause (<1, 20, 40, 60, and 120 days) and after arousal from diapause. Biochemical changes occurred early in diapausing animals, between the first 24 h and 20 days of diapause. Diapausing animals had reduced oxidative capacity associated with a decrease in the activities of peroxide-decomposing antioxidant enzymes. There was no sign of redox imbalance either during diapause or after recovery from diapause. Noteworthy, glutathione transferase and isocitrate dehydrogenase-NADP+ activities sharply increased in diapausing animals and stand out as diapause-associated proteins. The upregulation of these two enzymes ultimately indicate the occurrence of Preparation for Oxidative Stress in the tropical diapause of C. lacinia.