ABSTRACT
Nucleotide excision repair (NER) acts repairing damages in DNA, such as lesions caused by cisplatin. Xeroderma Pigmentosum complementation group C (XPC) protein is involved in recognition of global genome DNA damages during NER (GG-NER) and it has been studied in different organisms due to its importance in other cellular processes. In this work, we studied NER proteins in Trypanosoma cruzi and Trypanosoma evansi, parasites of humans and animals respectively. We performed three-dimensional models of XPC proteins from T. cruzi and T. evansi and observed few structural differences between these proteins. In our tests, insertion of XPC gene from T. evansi (TevXPC) in T. cruzi resulted in slower cell growth under normal conditions. After cisplatin treatment, T. cruzi overexpressing its own XPC gene (TcXPC) was able to recover cell division rates faster than T. cruzi expressing TevXPC gene. Based on these tests, it is suggested that TevXPC (being an exogenous protein in T. cruzi) interferes negatively in cellular processes where TcXPC (the endogenous protein) is involved. This probably occurred due interaction of TevXPC with some endogenous molecules or proteins from T. cruzi but incapacity of interaction with others. This reinforces the importance of correctly XPC functioning within the cell.
O reparo por excisão de nucleotídeos (NER) atua reparando danos no DNA, como lesões causadas por cisplatina. A proteína Xeroderma Pigmentosum complementation group C (XPC) está envolvida no reconhecimento de danos pela via de reparação global do genoma pelo NER (GG-NER) e tem sido estudada em diferentes organismos devido à sua importância em outros processos celulares. Neste trabalho, estudamos proteínas do NER em Trypanosoma cruzi e Trypanosoma evansi, parasitos de humanos e animais, respectivamente. Modelos tridimensionais das proteínas XPC de T. cruzi e T. evansi foram feitos e observou-se poucas diferenças estruturais entre estas proteínas. Durante testes, a inserção do gene XPC de T. evansi (TevXPC) em T. cruzi resultou em crescimento celular mais lento em condições normais. Após o tratamento com cisplatina, T. cruzi superexpressando seu próprio gene XPC (TcXPC) foi capaz de recuperar as taxas de divisão celular mais rapidamente do que T. cruzi expressando o gene TevXPC. Com base nesses testes, sugere-se que TevXPC (sendo uma proteína exógena em T. cruzi) interfere negativamente nos processos celulares em que TcXPC (a proteína endógena) está envolvida. Isso provavelmente ocorreu pois TevXPC é capaz de interagir com algumas moléculas ou proteínas endógenas de T. cruzi, mas é incapaz de interagir com outras. Isso reforça a importância do correto funcionamento de XPC dentro da célula.
Subject(s)
Animals , Crosses, Genetic , DNA Damage , Gene Expression , Trypanosoma cruzi/geneticsABSTRACT
Abstract Nucleotide excision repair (NER) acts repairing damages in DNA, such as lesions caused by cisplatin. Xeroderma Pigmentosum complementation group C (XPC) protein is involved in recognition of global genome DNA damages during NER (GG-NER) and it has been studied in different organisms due to its importance in other cellular processes. In this work, we studied NER proteins in Trypanosoma cruzi and Trypanosoma evansi, parasites of humans and animals respectively. We performed three-dimensional models of XPC proteins from T. cruzi and T. evansi and observed few structural differences between these proteins. In our tests, insertion of XPC gene from T. evansi (TevXPC) in T. cruzi resulted in slower cell growth under normal conditions. After cisplatin treatment, T. cruzi overexpressing its own XPC gene (TcXPC) was able to recover cell division rates faster than T. cruzi expressing TevXPC gene. Based on these tests, it is suggested that TevXPC (being an exogenous protein in T. cruzi) interferes negatively in cellular processes where TcXPC (the endogenous protein) is involved. This probably occurred due interaction of TevXPC with some endogenous molecules or proteins from T.cruzi but incapacity of interaction with others. This reinforces the importance of correctly XPC functioning within the cell.
Resumo O reparo por excisão de nucleotídeos (NER) atua reparando danos no DNA, como lesões causadas por cisplatina. A proteína Xeroderma Pigmentosum complementation group C (XPC) está envolvida no reconhecimento de danos pela via de reparação global do genoma pelo NER (GG-NER) e tem sido estudada em diferentes organismos devido à sua importância em outros processos celulares. Neste trabalho, estudamos proteínas do NER em Trypanosoma cruzi e Trypanosoma evansi, parasitos de humanos e animais, respectivamente. Modelos tridimensionais das proteínas XPC de T. cruzi e T. evansi foram feitos e observou-se poucas diferenças estruturais entre estas proteínas. Durante testes, a inserção do gene XPC de T. evansi (TevXPC) em T. cruzi resultou em crescimento celular mais lento em condições normais. Após o tratamento com cisplatina, T. cruzi superexpressando seu próprio gene XPC (TcXPC) foi capaz de recuperar as taxas de divisão celular mais rapidamente do que T. cruzi expressando o gene TevXPC. Com base nesses testes, sugere-se que TevXPC (sendo uma proteína exógena em T. cruzi) interfere negativamente nos processos celulares em que TcXPC (a proteína endógena) está envolvida. Isso provavelmente ocorreu pois TevXPC é capaz de interagir com algumas moléculas ou proteínas endógenas de T.cruzi, mas é incapaz de interagir com outras. Isso reforça a importância do correto funcionamento de XPC dentro da célula.
ABSTRACT
Abstract Nucleotide excision repair (NER) acts repairing damages in DNA, such as lesions caused by cisplatin. Xeroderma Pigmentosum complementation group C (XPC) protein is involved in recognition of global genome DNA damages during NER (GG-NER) and it has been studied in different organisms due to its importance in other cellular processes. In this work, we studied NER proteins in Trypanosoma cruzi and Trypanosoma evansi, parasites of humans and animals respectively. We performed three-dimensional models of XPC proteins from T. cruzi and T. evansi and observed few structural differences between these proteins. In our tests, insertion of XPC gene from T. evansi (TevXPC) in T. cruzi resulted in slower cell growth under normal conditions. After cisplatin treatment, T. cruzi overexpressing its own XPC gene (TcXPC) was able to recover cell division rates faster than T. cruzi expressing TevXPC gene. Based on these tests, it is suggested that TevXPC (being an exogenous protein in T. cruzi) interferes negatively in cellular processes where TcXPC (the endogenous protein) is involved. This probably occurred due interaction of TevXPC with some endogenous molecules or proteins from T.cruzi but incapacity of interaction with others. This reinforces the importance of correctly XPC functioning within the cell.
Resumo O reparo por excisão de nucleotídeos (NER) atua reparando danos no DNA, como lesões causadas por cisplatina. A proteína Xeroderma Pigmentosum complementation group C (XPC) está envolvida no reconhecimento de danos pela via de reparação global do genoma pelo NER (GG-NER) e tem sido estudada em diferentes organismos devido à sua importância em outros processos celulares. Neste trabalho, estudamos proteínas do NER em Trypanosoma cruzi e Trypanosoma evansi, parasitos de humanos e animais, respectivamente. Modelos tridimensionais das proteínas XPC de T. cruzi e T. evansi foram feitos e observou-se poucas diferenças estruturais entre estas proteínas. Durante testes, a inserção do gene XPC de T. evansi (TevXPC) em T. cruzi resultou em crescimento celular mais lento em condições normais. Após o tratamento com cisplatina, T. cruzi superexpressando seu próprio gene XPC (TcXPC) foi capaz de recuperar as taxas de divisão celular mais rapidamente do que T. cruzi expressando o gene TevXPC. Com base nesses testes, sugere-se que TevXPC (sendo uma proteína exógena em T. cruzi) interfere negativamente nos processos celulares em que TcXPC (a proteína endógena) está envolvida. Isso provavelmente ocorreu pois TevXPC é capaz de interagir com algumas moléculas ou proteínas endógenas de T.cruzi, mas é incapaz de interagir com outras. Isso reforça a importância do correto funcionamento de XPC dentro da célula.
Subject(s)
Humans , Animals , Trypanosoma cruzi/genetics , Xeroderma Pigmentosum , DNA Damage/genetics , Computational Biology , DNA-Binding Proteins/genetics , DNA-Binding Proteins/metabolism , DNA Repair/geneticsABSTRACT
Nucleotide excision repair (NER) acts repairing damages in DNA, such as lesions caused by cisplatin. Xeroderma Pigmentosum complementation group C (XPC) protein is involved in recognition of global genome DNA damages during NER (GG-NER) and it has been studied in different organisms due to its importance in other cellular processes. In this work, we studied NER proteins in Trypanosoma cruzi and Trypanosoma evansi, parasites of humans and animals respectively. We performed three-dimensional models of XPC proteins from T. cruzi and T. evansi and observed few structural differences between these proteins. In our tests, insertion of XPC gene from T. evansi (TevXPC) in T. cruzi resulted in slower cell growth under normal conditions. After cisplatin treatment, T. cruzi overexpressing its own XPC gene (TcXPC) was able to recover cell division rates faster than T. cruzi expressing TevXPC gene. Based on these tests, it is suggested that TevXPC (being an exogenous protein in T. cruzi) interferes negatively in cellular processes where TcXPC (the endogenous protein) is involved. This probably occurred due interaction of TevXPC with some endogenous molecules or proteins from T.cruzi but incapacity of interaction with others. This reinforces the importance of correctly XPC functioning within the cell.
Subject(s)
Trypanosoma cruzi , Xeroderma Pigmentosum , Animals , Computational Biology , DNA Damage/genetics , DNA Repair/genetics , DNA-Binding Proteins/genetics , DNA-Binding Proteins/metabolism , Humans , Trypanosoma cruzi/geneticsABSTRACT
Rheumatoid arthritis (RA), psoriatic arthritis (PsA), and ankylosing spondylitis (AS) are inflammatory diseases with different bone remodeling patterns. Fibroblast-like synoviocytes (FLS) are cells involved in the transition from an acute and reparable phase to a chronic and persistent stage in these diseases. The distinction of joint phenotypes involves inflammatory cytokines such as tumor necrosis factor alpha (TNF-α), interleukin (IL)-17, and IL-22 directly or through key signaling pathways such as Wnt. To evaluate the role of FLS as the source of Wnt antagonists (sFRP3/FRZB and Dkk1) in the synovia, levels of TNF- α, IL-17, IL-22, Dkk1, and sFRP3 were measured by ELISA directly in the synovial fluid of patients with RA, PsA, or AS. Dkk1 and sFRP3 were also measured in the FLS culture supernatants after different inflammatory stimulus. sFRP3 and Dkk1 are constitutively expressed by FLS. IL-22 and sFRP3 were positively correlated (r=0.76; P<0.01) in synovial fluid. The stimulation of FLS with IL-22, but not TNF-alpha and IL-17, increased the production of sFRP3. No stimulus altered the basal expression of Dkk1. These results showed, for the first time, the ability of IL-22 to increase the expression of sFRP3/FRZB by human FLS in both in vitro and ex vivo models. This finding linked IL-22 to local inhibition of Wnt signaling and possibly to blockade of osteogenesis. Furthermore, FLS presented as a source of this inhibitor in synovial fluid, assigning to this cell a bone injury mechanism.
Subject(s)
Interleukins/metabolism , Synoviocytes , Adult , Cells, Cultured , Female , Fibroblasts , Humans , Male , Middle Aged , Synovial Membrane , Tumor Necrosis Factor-alpha , Interleukin-22ABSTRACT
Rheumatoid arthritis (RA), psoriatic arthritis (PsA), and ankylosing spondylitis (AS) are inflammatory diseases with different bone remodeling patterns. Fibroblast-like synoviocytes (FLS) are cells involved in the transition from an acute and reparable phase to a chronic and persistent stage in these diseases. The distinction of joint phenotypes involves inflammatory cytokines such as tumor necrosis factor alpha (TNF-α), interleukin (IL)-17, and IL-22 directly or through key signaling pathways such as Wnt. To evaluate the role of FLS as the source of Wnt antagonists (sFRP3/FRZB and Dkk1) in the synovia, levels of TNF- α, IL-17, IL-22, Dkk1, and sFRP3 were measured by ELISA directly in the synovial fluid of patients with RA, PsA, or AS. Dkk1 and sFRP3 were also measured in the FLS culture supernatants after different inflammatory stimulus. sFRP3 and Dkk1 are constitutively expressed by FLS. IL-22 and sFRP3 were positively correlated (r=0.76; P<0.01) in synovial fluid. The stimulation of FLS with IL-22, but not TNF-alpha and IL-17, increased the production of sFRP3. No stimulus altered the basal expression of Dkk1. These results showed, for the first time, the ability of IL-22 to increase the expression of sFRP3/FRZB by human FLS in both in vitro and ex vivo models. This finding linked IL-22 to local inhibition of Wnt signaling and possibly to blockade of osteogenesis. Furthermore, FLS presented as a source of this inhibitor in synovial fluid, assigning to this cell a bone injury mechanism.
Subject(s)
Humans , Male , Female , Adult , Middle Aged , Interleukins/metabolism , Synoviocytes , Synovial Membrane , Cells, Cultured , Tumor Necrosis Factor-alpha , FibroblastsABSTRACT
Genomes are affected by a wide range of damage, which has resulted in the evolution of a number of widely conserved DNA repair pathways. Most of these repair reactions have been described in the African trypanosome Trypanosoma brucei, which is a genetically tractable eukaryotic microbe and important human and animal parasite, but little work has considered how the DNA damage response operates throughout the T. brucei life cycle. Using quantitative PCR we have assessed damage induction and repair in both the nuclear and mitochondrial genomes of the parasite. We show differing kinetics of repair for three forms of DNA damage, and dramatic differences in repair between replicative life cycle forms found in the testse fly midgut and the mammal. We find that mammal-infective T. brucei cells repair oxidative and crosslink-induced DNA damage more efficiently than tsetse-infective cells and, moreover, very distinct patterns of induction and repair of DNA alkylating damage in the two life cycle forms. We also reveal robust repair of DNA lesions in the highly unusual T. brucei mitochondrial genome (the kinetoplast). By examining mutants we show that nuclear alkylation damage is repaired by the concerted action of two repair pathways, and that Rad51 acts in kinetoplast repair. Finally, we correlate repair with cell cycle arrest and cell growth, revealing that induced DNA damage has strikingly differing effects on the two life cycle stages, with distinct timing of alkylation-induced cell cycle arrest and higher levels of damage induced death in mammal-infective cells. Our data reveal that T. brucei regulates the DNA damage response during its life cycle, a capacity that may be shared by many microbial pathogens that exist in variant environments during growth and transmission.
Subject(s)
DNA Damage , Trypanosoma brucei brucei/growth & development , Trypanosoma brucei brucei/genetics , Alkylation , Cell Cycle Checkpoints/genetics , DNA Adducts/metabolism , DNA Repair , DNA, Protozoan/genetics , DNA, Protozoan/metabolism , Oxidative Stress/genetics , Rad51 Recombinase/metabolism , Trypanosoma brucei brucei/cytology , Trypanosoma brucei brucei/metabolismABSTRACT
WHAT IS KNOWN AND OBJECTIVE: Malaria is a potentially severe disease, widespread in tropical and subtropical areas. Apart from parasite drug resistance, which receives the largest share of attention, several factors directly influence the response to antimalarial treatment such as incorrect doses, adverse drug events, lack of adherence to treatment, drug quality and drug-drug interactions. Pharmacotherapy follow-up can be used to monitor and improve the effectiveness of treatment, prevent drug-related problems and ensure patient safety. The aim of this study was to describe the results of the implementation of pharmacotherapy follow-up of patients with malaria seen at a reference centre for malaria diagnosis and treatment (CPD-Mal) located in the city of Rio de Janeiro, an area without malaria transmission. METHODS: A descriptive study was conducted from January 2009 to September 2013 at the Instituto Nacional de Infectologia Evandro Chagas (INI) of the Fundação Oswaldo Cruz (Fiocruz). All malaria patients enrolled in the study were treated according to the Brazilian Malaria Therapy Guidelines. Data collected during pharmacotherapy follow-up were recorded in a standardized form. The variables included were age, gender, comorbidities, antimalarials and concomitant medications used, adverse drug reactions (ADR), clinical and parasitological cure times, and treatment outcomes classified as success, recurrence (recrudescence or relapse); and lost to follow-up. The ADR were classified by severity (DAIDS-NIH), organ system affected (WHO-ART) and likelihood to be caused by drugs (Naranjo scale). RESULTS AND DISCUSSION: One hundred thirteen cases of malaria were included. Patients were aged between 13 and 66 years and the majority of them (75.2%) were male. Ninety-four ADR were observed, most classified as mild (85.1%), related to disorders of the gastrointestinal system (63.8%), such as nausea and vomiting, and assessed as "possibly" caused by the antimalarial drugs (91.5%). The majority of clinical (90.9%) and parasitological (87.1%) cure occurred less than 72 hours after treatment initiation. Pharmacotherapy follow-up of malaria treatment by surveillance activities is therefore important regarding information about treatment outcomes as well as patient safety, resulting in better patient care and reducing the chance of relapses. The results underscore its use as a tool for monitoring adherence and drug resistance outside an endemic area. WHAT IS NEW AND CONCLUSION: Pharmacotherapy follow-up should be considered a useful malaria surveillance tool that can be developed by reference centres for comprehensive health care assistance and monitoring of therapeutic resistance.
Subject(s)
Antimalarials/therapeutic use , Malaria/drug therapy , Adolescent , Adult , Antimalarials/adverse effects , Brazil , Child , Drug Resistance , Drug-Related Side Effects and Adverse Reactions/etiology , Female , Follow-Up Studies , Humans , Male , Middle Aged , Recurrence , Travel Medicine/methods , Treatment Outcome , Young AdultABSTRACT
Trypanosoma cruzi genetic diversity was investigated in 25 isolates (vectors and humans) from the semiarid zone of the State of Rio Grande do Norte, Brazil. Molecular markers (3' region of the 24Salpha rRNA; mitochondrial cytochrome oxidase subunit 2 (COII) gene; spliced leader intergenic region (SL-IR) gene; allelic size microsatellite polymorphism) identified 56% TcIII (100% Panstrongyluslutzi; 50% Triatomabrasiliensis); 40% TcII (91.7% humans; 50% T. brasiliensis) and 4% TcI (human). Microsatellite analysis revealed monoclonal and heterozygous patterns on one or more microsatellite loci in 64% of T. cruzi isolates (92.3% triatomines; 33.3% humans) and 36% putative polyclonal populations (66.7% humans; 7.7% triatomines) by loci SCLE10, SCLE11, TcTAT20, TcAAAT6, all belonging to TcII. Identical T. cruzi polyclonal profiles (88.9%) were detected, mostly from humans. The adaptative natural plasticity of TcII and TcIII and their potential for maintaining human infection in T. brasiliensis were confirmed. Intraspecific and phylogenetic T. cruzi diversity in the sylvatic and domestic transmission cycles in this specific region will provide exclusive control strategies.
Subject(s)
Chagas Disease/parasitology , Genetic Variation , Triatoma/parasitology , Trypanosoma cruzi/classification , Trypanosoma cruzi/genetics , Animals , Brazil , Cluster Analysis , DNA, Protozoan/genetics , Genotype , Humans , Microsatellite Repeats , Trypanosoma cruzi/isolation & purificationABSTRACT
In an effort to unify the nomenclature of Trypanosoma cruzi, the causative agent of Chagas disease, an updated system was agreed upon at the Second Satellite Meeting. A consensus was reached that T. cruzi strains should be referred to by six discrete typing units (T. cruzi I-VI). The goal of a unified nomenclature is to improve communication within the scientific community involved in T. cruzi research. The justification and implications will be presented in a subsequent detailed report.
Subject(s)
Terminology as Topic , Trypanosoma cruzi/classification , AnimalsABSTRACT
Nucleotide excision repair (NER) acts on a broad spectrum of large lesions, while base excision repair removes individual modified bases. Although both processes have been well studied in human cells, novel genes involved in these DNA repair pathways have been described. Using a heterologous complementation approach, we identified a fetal human cDNA that complemented two Escherichia coli mutants that are defective in 3-methyl adenine glycosylase and in three endonucleases, all of which are enzymes with important roles in base excision repair. The central cDNA open reading frame complemented NER mutant strains and promoted an increase in survival rate of bacteria exposed to UV light. The corresponding protein was able to restore nucleotide-excision-repair activity when added to a cell extract from Chinese hamster ovary cells deficient in the ERCC1 protein, an enzyme known to promote incision at the 5' end of the lesion during NER. In contrast, that protein was not able to complement XPG Chinese hamster ovary cells deficient in the 3' incision step of NER. These data indicate a new human repair gene, which we named HC1; it is involved in the recognition of two kinds of DNA lesions and it contributes to the 5' DNA incision step in NER.
Subject(s)
DNA Repair/genetics , DNA-Binding Proteins/genetics , Amino Acid Sequence , Animals , Base Sequence , CHO Cells , Cricetinae , Cricetulus , DNA Damage , DNA, Complementary/genetics , DNA, Complementary/metabolism , Escherichia coli/genetics , Escherichia coli/metabolism , Genetic Complementation Test , Humans , Molecular Sequence DataABSTRACT
DNA polymerase kappa (Pol kappa) is a low-fidelity polymerase that has the ability to bypass several types of lesions. The biological role of this enzyme, a member of the DinB subfamily of Y-family DNA polymerases, has remained elusive. In this report, we studied one of the two copies of Pol kappa from the protozoan Trypanosoma cruzi (TcPol kappa). The role of this TcPol kappa copy was investigated by analysing its subcellular localization, its activities in vitro, and performing experiments with parasites that overexpress this polymerase. The TcPOLK sequence has the N-terminal extension which is present only in eukaryotic DinB members, but its C-terminal region is more similar to prokaryotic and archaeal counterparts since it lacks C(2)HC motifs and PCNA interaction domain. Our results indicate that in contrast to its previously described orthologues, this polymerase is localized to mitochondria. The overexpression of TcPOLK increases T. cruzi resistance to hydrogen peroxide, and in vitro polymerization assays revealed that TcPol kappa efficiently bypasses 8-oxoguanine lesions. Remarkably, our results also demonstrate that the DinB subfamily of polymerases can participate in homologous recombination, based on our findings that TcPol kappa increases T. cruzi resistance to high doses of gamma irradiation and zeocin and can catalyse DNA synthesis within recombination intermediates.
Subject(s)
DNA Replication , DNA-Directed DNA Polymerase/metabolism , Guanine/analogs & derivatives , Mitochondria/genetics , Protozoan Proteins/metabolism , Trypanosoma cruzi/genetics , Amino Acid Sequence , Animals , DNA Damage , DNA, Protozoan/genetics , DNA-Directed DNA Polymerase/genetics , Guanine/metabolism , Hydrogen Peroxide/pharmacology , Molecular Sequence Data , Oxidative Stress , Protozoan Proteins/genetics , Recombination, Genetic , Trypanosoma cruzi/drug effects , Trypanosoma cruzi/metabolismABSTRACT
Different strains of Trypanosoma cruzi were transfected with an expression vector that allows the integration of green fluorescent protein (GFP) and red fluorescent protein (RFP) genes into the beta-tubulin locus by homologous recombination. The sites of integration of the GFP and RFP markers were determined by pulse-field gel electrophoresis and Southern blot analyses. Cloned cell lines selected from transfected epimastigote populations maintained high levels of fluorescent protein expression even after 6 months of in vitro culture of epimastigotes in the absence of drug selection. Fluorescent trypomastigotes and amastigotes were observed within Vero cells in culture as well as in hearts and diaphragms of infected mice. The infectivity of the GFP- and RFP-expressing parasites in tissue culture cells was comparable to wild type populations. Furthermore, GFP- and RFP-expressing parasites were able to produce similar levels of parasitemia in mice compared with wild type parasites. Cell cultures infected simultaneously with two cloned cell lines from the same parasite strain, each one expressing a distinct fluorescent marker, showed that at least two different parasites are able to infect the same cell. Double-infected cells were also detected when GFP- and RFP-expressing parasites were derived from strains belonging to two distinct T. cruzi lineages. These results show the usefulness of parasites expressing GFP and RFP for the study of various aspects of T. cruzi infection including the mechanisms of cell invasion, genetic exchange among parasites and the differential tissue distribution in animal models of Chagas disease.
Subject(s)
Chagas Disease/parasitology , Green Fluorescent Proteins/genetics , Luminescent Proteins/genetics , Trypanosoma cruzi/genetics , Animals , Chlorocebus aethiops , Electrophoresis, Polyacrylamide Gel , Flow Cytometry , Gene Expression , Humans , Immunoblotting/methods , Interferon-gamma/genetics , Mice , Mice, Knockout , Microscopy, Confocal , Models, Animal , Parasitology/methods , Transfection/methods , Vero Cells , Red Fluorescent ProteinABSTRACT
Although different DNA polymerases have distinct functions and substrate affinities, their general mechanism of action is similar. Thus, they can all be studied using the same technical principle, the primer extension assay employing radioactive tags. Even though fluorescence has been used routinely for many years for DNA sequencing, it has not been used in the in vitro primer extension assay. The use of fluorescence labels has obvious advantages over radioactivity, including safety, speed and ease of manipulation. In the present study, we demonstrated the potential of non-radioactive in vitro primer extension for DNA polymerase studies. By using an M13 tag in the substrate, we can use the same fluorescent M13 primer to study different substrate sequences. This technique allows quantification of the DNA polymerase activity of the Klenow fragment using different templates and under different conditions with similar sensitivity to the radioactive assay.
Subject(s)
DNA Polymerase I/metabolism , DNA Primers/metabolism , Escherichia coli/enzymology , Fluorescein/metabolism , Sequence Analysis, DNA , Automation , Hydrogen-Ion ConcentrationABSTRACT
Chagas' disease, caused by the protozoan Trypanosoma cruzi, is a major cause of cardiovascular disability in countries where it is endemic. Damage to the heart microvasculature has been proposed to be an important factor in the pathogenesis of heart dysfunction. Endothelin-1 (ET-1) is a potent vasoconstrictor and exerts its effects via specific ET A and ET B receptors. A few studies have suggested a role for ET-1 and its receptors in the pathogenesis of Chagas' disease. We investigated the effects of treatment with bosentan, an ET A/ET B receptor antagonist, on the course of T. cruzi infection (Y strain) in C57Bl/6 mice. Treatment with bosentan (100 mg kg-1 day-1) was given per os starting day 0 after infection until sacrifice. Bosentan significantly increased myocardial inflammation, with no effects on parasitemia. Although the total number of nests was similar, a lower number of intact amastigote nests was found in the heart of bosentan-treated animals. Bosentan failed to affect the infection-associated increase in the cardiac levels of the cytokines IFN-g and TNF-a and the chemokines CCL2/MCP-1, CCL3/MIP-1a and CCL5/RANTES. In vitro, pre-incubation with ET-1 (0.1 microM) 4 h before infection enhanced the uptake of the parasites by peritoneal macrophages, and this effect was abrogated when macrophages were pre-treated with bosentan (1 microM) 15 min before incubation with ET-1. However, ET-1 did not alter killing of intracellular parasites after 48 h of in vitro infection. Our data suggest that bosentan-treated mice have a delay in controlling parasitism which is compensated for exacerbated inflammation. Infection is eventually controlled in these animals and lethality is unchanged, demonstrating that ET-1 plays a minor role in the protection against acute murine T. cruzi infection.
Subject(s)
Chagas Cardiomyopathy/metabolism , Endothelin Receptor Antagonists , Endothelin-1/physiology , Parasitemia/metabolism , Sulfonamides/pharmacology , Trypanosoma cruzi/drug effects , Acute Disease , Animals , Bosentan , Chagas Cardiomyopathy/drug therapy , Chagas Cardiomyopathy/parasitology , Cytokines/analysis , Disease Models, Animal , Male , Mice , Mice, Inbred C57BL , Parasitemia/drug therapy , Parasitemia/immunologyABSTRACT
Chagas' disease, caused by the protozoan Trypanosoma cruzi, is a major cause of cardiovascular disability in countries where it is endemic. Damage to the heart microvasculature has been proposed to be an important factor in the pathogenesis of heart dysfunction. Endothelin-1 (ET-1) is a potent vasoconstrictor and exerts its effects via specific ET A and ET B receptors. A few studies have suggested a role for ET-1 and its receptors in the pathogenesis of Chagas' disease. We investigated the effects of treatment with bosentan, an ET A/ET B receptor antagonist, on the course of T. cruzi infection (Y strain) in C57Bl/6 mice. Treatment with bosentan (100 mg kg-1 day-1) was given per os starting day 0 after infection until sacrifice. Bosentan significantly increased myocardial inflammation, with no effects on parasitemia. Although the total number of nests was similar, a lower number of intact amastigote nests was found in the heart of bosentan-treated animals. Bosentan failed to affect the infection-associated increase in the cardiac levels of the cytokines IFN-g and TNF-a and the chemokines CCL2/MCP-1, CCL3/MIP-1a and CCL5/RANTES. In vitro, pre-incubation with ET-1 (0.1 æM) 4 h before infection enhanced the uptake of the parasites by peritoneal macrophages, and this effect was abrogated when macrophages were pre-treated with bosentan (1 æM) 15 min before incubation with ET-1. However, ET-1 did not alter killing of intracellular parasites after 48 h of in vitro infection. Our data suggest that bosentan-treated mice have a delay in controlling parasitism which is compensated for exacerbated inflammation. Infection is eventually controlled in these animals and lethality is unchanged, demonstrating that ET-1 plays a minor role in the protection against acute murine T. cruzi infection.
Subject(s)
Animals , Male , Mice , Chagas Cardiomyopathy/metabolism , Endothelin-1/physiology , Parasitemia/metabolism , Receptors, Endothelin/antagonists & inhibitors , Sulfonamides/pharmacology , Trypanosoma cruzi/physiology , Acute Disease , Chagas Cardiomyopathy/parasitology , Chagas Cardiomyopathy/pathology , Cytokines/analysis , Disease Models, Animal , Parasitemia/immunology , Trypanosoma cruzi/isolation & purificationABSTRACT
The low-fidelity DNA polymerases thought to be specialized in DNA damage processing are frequently misregulated in cancers. We show here that DNA polymerase kappa (polkappa), prone to replicate across oxidative and aromatic adducts and known to function in nucleotide excision repair (NER), is downregulated in colorectal tumour biopsies. Contrary to the replicative poldelta and polalpha, for which only activating domains were described, we identified an upstream 465-bp-long repressor region in the promoter of POLK. We also found an activating 237-bp region that includes stimulating protein-1 (SP1) and cyclic AMP-responsive element (CRE)-binding sites. Mutations at one CRE-binding site led to a dramatic 80% decrease in promoter activity. Alterations of the SP1-binding site also affected, to a lesser extent, the transcription. Gel shift assays confirmed the role played by CRE/SP1 recognition sequences. Moreover, ectopic expression of SP1 or CRE-binding protein (CREB) protein favoured polkappa transcription. Finally, we found that polkappa downexpression in colorectal biopsies correlated with a decreased level of CREB and SP1 transcripts. This work shows that the promoter of POLK is cis-controlled and suggests that silencing of CREB and SP1 proteins could contribute to downregulation of this repair polymerase in colorectal tumours.
Subject(s)
Colorectal Neoplasms/enzymology , Colorectal Neoplasms/genetics , DNA-Directed DNA Polymerase/metabolism , Down-Regulation , Gene Expression Regulation, Neoplastic , Promoter Regions, Genetic/genetics , Acetylation , Biopsy , Colorectal Neoplasms/pathology , DNA/metabolism , DNA-Binding Proteins/genetics , DNA-Binding Proteins/metabolism , DNA-Directed DNA Polymerase/genetics , Humans , Middle Aged , Mutation/genetics , RNA, Messenger/genetics , Regulatory Sequences, Nucleic Acid , Transcription, Genetic/geneticsABSTRACT
Although different DNA polymerases have distinct functions and substrate affinities, their general mechanism of action is similar. Thus, they can all be studied using the same technical principle, the primer extension assay employing radioactive tags. Even though fluorescence has been used routinely for many years for DNA sequencing, it has not been used in the in vitro primer extension assay. The use of fluorescence labels has obvious advantages over radioactivity, including safety, speed and ease of manipulation. In the present study, we demonstrated the potential of non-radioactive in vitro primer extension for DNA polymerase studies. By using an M13 tag in the substrate, we can use the same fluorescent M13 primer to study different substrate sequences. This technique allows quantification of the DNA polymerase activity of the Klenow fragment using different templates and under different conditions with similar sensitivity to the radioactive assay.
Subject(s)
Sequence Analysis, DNA , DNA Polymerase I/metabolism , Escherichia coli/enzymology , Fluorescein/metabolism , DNA Primers/metabolism , Automation , Hydrogen-Ion ConcentrationABSTRACT
The rat model of hypertension induced by prolonged treatment with Nomega-nitro-L-arginine methyl ester (L-NAME) has been extensively used. However, the effects on cardiac autonomic innervation are unknown. Here, the cardiac sympathetic innervation is analyzed in parallel with myocardial lesions and leukocyte infiltration during L-NAME (40 mg/Kg body weight/day, orally) treatment. The occurrence of cardiomyocyte hypertrophy, a controversial matter, is also addressed. Degenerating cardiomyocytes and focal inflammation occurred one day after treatment. Inflammatory lesions became gradually more frequent until day 7. At day 14 fibroblast-like cells were outstanding. Interstitial and perivascular connective tissue increased from day 28 on. In the left ventricle, cardiomyocyte hypertrophy occurred only around the damaged area during the first 14 days. After 28 days, it became more widespread. In the right ventricle, the hypertrophic cardiomyocytes were restricted to damaged areas. Significant reduction of the noradrenergic nerve terminals occurred from day 3 to 28. The area occupied by ED1+ (hematogenous) macrophages increased until day 7, and dropped to control levels by day 10. ED2+ (resident) macrophages increased from day 3 to 7 and remained higher than control values up to day 77. Animals receiving both L- NAME and aminoguanidine (AG), an inducible nitric oxide synthase (iNOS) inhibitor (65 mg/Kg body weight/day, orally), showed significant decrease in the nitrite serum levels, sympathetic denervation and macrophage infiltration at day 7. No denervation was detectable at day 14 of double treatment, using subcutaneous AG. Our findings favor a role for ED1+ macrophages and iNOS in the hypertension-induced denervation process.
Subject(s)
Enzyme Inhibitors/toxicity , Heart/innervation , Hypertension/chemically induced , Macrophages/pathology , NG-Nitroarginine Methyl Ester/toxicity , Sympathectomy, Chemical , Sympathetic Nervous System/drug effects , Animals , Drug Therapy, Combination , Guanidines/pharmacology , Hemodynamics/drug effects , Hypertension/pathology , Macrophages/metabolism , Male , Myocytes, Cardiac/drug effects , Myocytes, Cardiac/metabolism , Myocytes, Cardiac/pathology , Nitric Oxide Synthase Type II/antagonists & inhibitors , Nitrites/blood , Rats , Rats, Sprague-Dawley , Sympathetic Nervous System/pathologyABSTRACT
Although Chagas' disease is known to provoke severe acute myositis, information on muscle regeneration is missing. The current paper shows that during T. cruzi infection in rats, skeletal muscle parasitism and the consequent inflammatory process are higher in muscle with a high proportion of type-I myofibres (soleus and diaphragm). Immunohistochemistry showed an acute inflammatory process characterized by ED1+ and ED2+ macrophages, CD8+ lymphocytes, and NK cells. Parasite-nest rupture provoked segmental degeneration of myofibres followed by regeneration. These phenomena were observed at both light and transmission electron microscopy levels. Myofibre regeneration involved activation of satellite cells assessed by the expression of MyoD, a muscle-specific transcription factor. Ultrastructural evidence of fusion of myoblast-like cells with the intact segment of degenerating fibres has been provided. At the chronic phase no signs of fibrosis were found, but sparse and small inflammatory foci were found. Our results argue against the relevant participation of autoimmunity phenomena in both acute and chronic phases and furnish a new view for explaining histopathological findings in human patient muscles.
