RESUMO
Objective The objective of this study was to assess the impact of systemic lupus erythematosus (SLE) on patients and carers. Methods Adults with SLE and carers of SLE patients completed a UK-specific online survey covering many aspects of the disease. Surveys were developed in collaboration with an NHS lupus unit and a lupus patient organization. Results A total of 121 patients and 31 carers completed the surveys. Of the 70% of patients initially misdiagnosed with another condition, 59% received treatment for the misdiagnosis. Fatigue was the most debilitating symptom, experienced daily by 79% of patients. The proportion of patients not reporting flares to healthcare providers varied with flare severity: mild flares (43%), moderate flares (15%) and severe flares (5%). Most patients (89%) reported reduced ability to socialize, and 76% had changed employment; of these, 52% stopped working completely. Over one-half (52%) of carers in paid employment missed time from work, and 55% of carers reported a worsened financial status. Most carers (87%) experienced interference with social activities. Conclusion SLE is commonly misdiagnosed and has a considerable impact on the physical, social and financial status of patients and carers. Increased awareness of the disease among healthcare providers and employers of patients and their carers is needed.
Assuntos
Cuidadores/estatística & dados numéricos , Efeitos Psicossociais da Doença , Fadiga/epidemiologia , Lúpus Eritematoso Sistêmico/fisiopatologia , Adolescente , Adulto , Idoso , Estudos Transversais , Erros de Diagnóstico/estatística & dados numéricos , Emprego/estatística & dados numéricos , Fadiga/etiologia , Feminino , Humanos , Internet , Lúpus Eritematoso Sistêmico/complicações , Lúpus Eritematoso Sistêmico/diagnóstico , Masculino , Pessoa de Meia-Idade , Qualidade de Vida , Índice de Gravidade de Doença , Inquéritos e Questionários , Reino Unido , Adulto JovemRESUMO
BACKGROUND: Health-related quality of life (HRQoL) from diagnosis until end of treatment for children with acute lymphoblastic leukaemia was investigated, examining effects of age, gender, risk-stratified treatment regimen, and therapy intensity (one vs. two 'delayed intensifications' [DIs]). METHOD: In a multi-centre prospective study, parents reported their child's generic and disease-specific HRQoL and their own care-giving burden at five time points. From 1,428 eligible patients, 874 parents completed questionnaires at least once during treatment. RESULTS: At each time point, generic HRQoL was significantly lower than equivalent norm scores for healthy children. HRQoL decreased significantly at the start of treatment, before recovering gradually (but remained below pre-treatment levels). Parents reported that older children worried more about side effects and their appearance, but showed less procedural anxiety than younger children. Concern for appearance was greater among girls than boys. Compared to Regimen B (i.e. additional doxorubicin during induction and additional cyclophosphamide and cytarabine during consolidation chemotherapy), patients receiving Regimen A had fewer problems with pain and nausea. There were no statistically significant differences in HRQoL by number of DI blocks received. INTERPRETATION: HRQoL is compromised at all stages of treatment, and is partly dependent on age. The findings increase understanding of the impact of therapy on children's HRQoL and parental care-giving burden, and will contribute to the design of future trials.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamento farmacológico , Qualidade de Vida , Adolescente , Adulto , Criança , Pré-Escolar , Quimioterapia de Consolidação , Ciclofosfamida/administração & dosagem , Citarabina/administração & dosagem , Doxorrubicina/administração & dosagem , Feminino , Seguimentos , Humanos , Lactente , Masculino , Prognóstico , Estudos Prospectivos , Inquéritos e Questionários , Adulto JovemRESUMO
Biotinidase deficiency is an autosomal recessive inherited disorder that is characterized by neurological and cutaneous symptoms. Biotinidase-deficient children cannot recycle endogenous biotin, an essential water-soluble B vitamin. Biotin is covalently attached to epsilon-amino groups of lysyl residues of four carboxylases. These carboxylases are subsequently degraded to biocytin (biotin-epsilon-lysine). Biotinidase cleaves biocytin to biotin and lysine, thereby completing the biotin cycle. The symptoms of biotinidase deficiency can be resolved or prevented by treatment with biotin. Therefore, it is important that biotinidase deficiency is diagnosed early so that permanent neurological damage can be prevented. Many states and countries currently perform newborn screening for biotinidase deficiency. We have recently isolated and characterized the cDNA for normal human biotinidase and localized the gene to chromosome 3p25 (ref. 9). We have now identified the first mutation that causes profound biotinidase deficiency. It occurs in a distinct region of the gene that encodes the putative signal peptide. Fifty percent of symptomatic children studied have a 7-bp deletion coupled with a 3-bp insertion in at least one of their alleles of the biotinidase gene. This mutation appears to be a common cause of biotinidase deficiency in symptomatic children.
Assuntos
Amidoidrolases/genética , Alelos , Amidoidrolases/deficiência , Sequência de Bases , Biotina/metabolismo , Biotinidase , Criança , Análise Mutacional de DNA , Feminino , Genes , Humanos , Recém-Nascido , Masculino , Dados de Sequência Molecular , Mutação , Linhagem , Reação em Cadeia da Polimerase , Polimorfismo Conformacional de Fita SimplesRESUMO
BACKGROUND: The public transit is a built environment with high occupant density across the globe, and identifying factors shaping public transit air microbiomes will help design strategies to minimize the transmission of pathogens. However, the majority of microbiome works dedicated to the public transit air are limited to amplicon sequencing, and our knowledge regarding the functional potentials and the repertoire of resistance genes (i.e. resistome) is limited. Furthermore, current air microbiome investigations on public transit systems are focused on single cities, and a multi-city assessment of the public transit air microbiome will allow a greater understanding of whether and how broad environmental, building, and anthropogenic factors shape the public transit air microbiome in an international scale. Therefore, in this study, the public transit air microbiomes and resistomes of six cities across three continents (Denver, Hong Kong, London, New York City, Oslo, Stockholm) were characterized. RESULTS: City was the sole factor associated with public transit air microbiome differences, with diverse taxa identified as drivers for geography-associated functional potentials, concomitant with geographical differences in species- and strain-level inferred growth profiles. Related bacterial strains differed among cities in genes encoding resistance, transposase, and other functions. Sourcetracking estimated that human skin, soil, and wastewater were major presumptive resistome sources of public transit air, and adjacent public transit surfaces may also be considered presumptive sources. Large proportions of detected resistance genes were co-located with mobile genetic elements including plasmids. Biosynthetic gene clusters and city-unique coding sequences were found in the metagenome-assembled genomes. CONCLUSIONS: Overall, geographical specificity transcends multiple aspects of the public transit air microbiome, and future efforts on a global scale are warranted to increase our understanding of factors shaping the microbiome of this unique built environment.
Assuntos
Microbiota , Bactérias/genética , Geografia , Hong Kong , Humanos , Metagenoma/genética , Microbiota/genéticaRESUMO
CBA/J mice are resistant to Leishmania major infection but are permissive to L. amazonensis infection. In addition, CBA/J macrophages control L. major but not L. amazonensis infection in vitro. Phagocytosis by macrophages is known to determine the outcome of Leishmania infection. Pattern recognition receptors (PRR) adorning antigen presenting cell surfaces are known to coordinate the link between innate and adaptive immunity. The macrophage receptor with collagenous structure (MARCO) is a PRR that is preferably expressed by macrophages and is capable of binding Gram-positive and Gram-negative bacteria. No research on the role of MARCO in Leishmania-macrophage interactions has been reported. Here, we demonstrate, for the first time, that MARCO expression by CBA/J macrophages is increased in response to both in vitro and in vivo L. major infections, but not to L. amazonensis infection. In addition, a specific anti-MARCO monoclonal antibody reduced L. major infection of macrophages by 30%-40% in vitro. The draining lymph nodes of anti-MARCO-treated mice displayed a reduced presence of immunolabelled parasite and parasite antigens, as well as a reduced inflammatory response. These results support the hypothesis that MARCO has a role in macrophage infection by L. major in vitro as well as in vivo.
Assuntos
Leishmania major/imunologia , Leishmaniose/imunologia , Leishmaniose/metabolismo , Macrófagos Peritoneais/imunologia , Receptores Imunológicos/biossíntese , Animais , Anticorpos Antiprotozoários/imunologia , Anticorpos Antiprotozoários/metabolismo , Imunidade Inata , Leishmania major/metabolismo , Leishmania mexicana/imunologia , Leishmania mexicana/metabolismo , Leishmaniose/parasitologia , Leishmaniose/patologia , Linfonodos/imunologia , Linfonodos/patologia , Macrófagos Peritoneais/metabolismo , Camundongos , Camundongos Endogâmicos CBA , Receptores Imunológicos/genética , Receptores Imunológicos/imunologia , Receptores Depuradores/biossíntese , Receptores Depuradores/genética , Receptores Depuradores/imunologia , Ativação Transcricional , Regulação para CimaRESUMO
AIMS: To determine the occurrence of the human pathogen, Vibrio vulnificus, in south Texas coastal waters. METHODS AND RESULTS: Coastal waters were sampled monthly between August 2006 and July 2007. Water temperature, dissolved oxygen, pH, salinity, conductivity and turbidity were measured during each sampling event. Culture-based techniques utilizing Vibrio vulnificus agar (VVA) and membrane-Enterococcus indoxyl-beta-D-glucoside agar (mEI) were used to assess the occurrence and levels of V. vulnificus and the faecal contamination indicator group, enterococci, respectively. Vibrio vulnificus isolates were confirmed using colony-blot hybridization with the species-specific VVAP probe. Vibrio vulnificus was isolated at all sites throughout the year even when the water temperature dropped to 9.71 degrees C. Significant correlations were found between concentrations of V. vulnificus and the abiotic factors, water temperature (P = 0.002) and dissolved oxygen (P = 0.028), as well as between concentrations of V. vulnificus and enterococci (P < 0.001). CONCLUSIONS: This study demonstrated the year-round presence of V. vulnificus in coastal waters of south Texas. SIGNIFICANCE AND IMPACT OF THE STUDY: These findings indicate that the potential for human exposure to the pathogen, V. vulnificus, exists throughout the year. It also suggests that routinely monitored data might be used to predict the occurrence of the pathogen.
Assuntos
Água do Mar/microbiologia , Vibrio vulnificus/isolamento & purificação , Praias , Contagem de Colônia Microbiana , Enterococcaceae/isolamento & purificação , Humanos , Água do Mar/análise , Temperatura , TexasRESUMO
Variant surface glycoprotein (VSG) genes of African trypanosomes are expressed when they are inserted into one of several telomere-linked expression sites. We cloned and characterized an 11-kilobase (kb) DNA fragment located upstream of an expressed VSG gene. A DNA sequence of 1.8 kb that is located immediately upstream of the inserted VSG gene contains sequences homologous to the 76-base-pair repeats described as being upstream of VSG genes in Trypanosoma brucei (D. A. Campbell, M. P. Van Bree, and J. C. Boothroyd, Nucleic Acids Res. 12:2759-2774). There are no such sequences elsewhere in the 11-kb cloned region. Southern blot analysis using probes from the cloned region revealed multiple unlinked copies of the same or very similar regions. At least three of these are located near telomeres, and two have been shown to be used for the expression of known Trypanosoma equiperdum VSG genes. Like VSG genes, the upstream sequences themselves can be duplicated and deleted. The choice of expression site to be used by a duplicated VSG gene is nonrandom; the site used for expression of the parental VSG gene is strongly favored for use in the daughter variant. Furthermore, even when the parental expression site is not used, the VSG gene occupying it is replaced. Thus, an active expression site is a preferential target for gene conversion in the next variation event.
Assuntos
Clonagem Molecular , Regulação da Expressão Gênica , Glicoproteínas/genética , Trypanosoma/genética , Animais , Antígenos de Protozoários/genética , Sequência de Bases , Enzimas de Restrição do DNA/metabolismo , Epitopos/genética , Ligação Genética , Sequências Repetitivas de Ácido Nucleico , Glicoproteínas Variantes de Superfície de TrypanosomaRESUMO
Antigenic variation in Trypanosoma equiperdum is associated with the sequential expression of variant surface glycoprotein (VSG) genes in a process which involves gene duplication and transposition events. In this paper we present evidence that the genomic environment of the VSG-1 basic copy gene, the template for duplicated, expression-linked VSG-1 genes, differs in every trypanosome clone examined. This variation is thus independent of the expression of the VSG-1 gene, and it also appears to be restricted to the 3' genomic environment. It is also demonstrated that the DNA located 3' to the VSG-1 basic copy gene is moderately sensitive to digestion when the nuclei of either expressor or non-expressor trypanosomes are treated with DNase I.
Assuntos
DNA/análise , Glicoproteínas/genética , Trypanosoma/genética , Animais , Enzimas de Restrição do DNA/metabolismo , Desoxirribonuclease BamHI , Desoxirribonuclease EcoRI , Desoxirribonuclease I , Endodesoxirribonucleases/metabolismo , Regulação da Expressão Gênica , Glicoproteínas Variantes de Superfície de TrypanosomaRESUMO
BACKGROUND: Results of previous randomised trials have shown that interventions that lower LDL cholesterol concentrations can significantly reduce the incidence of coronary heart disease (CHD) and other major vascular events in a wide range of individuals. But each separate trial has limited power to assess particular outcomes or particular categories of participant. METHODS: A prospective meta-analysis of data from 90,056 individuals in 14 randomised trials of statins was done. Weighted estimates were obtained of effects on different clinical outcomes per 1.0 mmol/L reduction in LDL cholesterol. FINDINGS: During a mean of 5 years, there were 8186 deaths, 14,348 individuals had major vascular events, and 5103 developed cancer. Mean LDL cholesterol differences at 1 year ranged from 0.35 mmol/L to 1.77 mmol/L (mean 1.09) in these trials. There was a 12% proportional reduction in all-cause mortality per mmol/L reduction in LDL cholesterol (rate ratio [RR] 0.88, 95% CI 0.84-0.91; p<0.0001). This reflected a 19% reduction in coronary mortality (0.81, 0.76-0.85; p<0.0001), and non-significant reductions in non-coronary vascular mortality (0.93, 0.83-1.03; p=0.2) and non-vascular mortality (0.95, 0.90-1.01; p=0.1). There were corresponding reductions in myocardial infarction or coronary death (0.77, 0.74-0.80; p<0.0001), in the need for coronary revascularisation (0.76, 0.73-0.80; p<0.0001), in fatal or non-fatal stroke (0.83, 0.78-0.88; p<0.0001), and, combining these, of 21% in any such major vascular event (0.79, 0.77-0.81; p<0.0001). The proportional reduction in major vascular events differed significantly (p<0.0001) according to the absolute reduction in LDL cholesterol achieved, but not otherwise. These benefits were significant within the first year, but were greater in subsequent years. Taking all years together, the overall reduction of about one fifth per mmol/L LDL cholesterol reduction translated into 48 (95% CI 39-57) fewer participants having major vascular events per 1000 among those with pre-existing CHD at baseline, compared with 25 (19-31) per 1000 among participants with no such history. There was no evidence that statins increased the incidence of cancer overall (1.00, 0.95-1.06; p=0.9) or at any particular site. INTERPRETATION: Statin therapy can safely reduce the 5-year incidence of major coronary events, coronary revascularisation, and stroke by about one fifth per mmol/L reduction in LDL cholesterol, largely irrespective of the initial lipid profile or other presenting characteristics. The absolute benefit relates chiefly to an individual's absolute risk of such events and to the absolute reduction in LDL cholesterol achieved. These findings reinforce the need to consider prolonged statin treatment with substantial LDL cholesterol reductions in all patients at high risk of any type of major vascular event.
Assuntos
LDL-Colesterol/sangue , Inibidores de Hidroximetilglutaril-CoA Redutases/uso terapêutico , Hipercolesterolemia/tratamento farmacológico , Causas de Morte , Doença das Coronárias/mortalidade , Doença das Coronárias/prevenção & controle , Humanos , Inibidores de Hidroximetilglutaril-CoA Redutases/efeitos adversos , Infarto do Miocárdio/mortalidade , Ensaios Clínicos Controlados Aleatórios como Assunto , Fatores de Risco , Acidente Vascular Cerebral/mortalidade , Acidente Vascular Cerebral/prevenção & controle , Resultado do TratamentoRESUMO
A patient with a long history of arthritis developed pneumonia. Two weeks into her hospital course, the patient developed effusions in her knee and wrist that yielded cultures positive for Mycoplasma pneumoniae. To our knowledge, this is the third reported case of M pneumoniae isolation from a joint and the first report of isolation of M pneumoniae from two joints in a patient without hypogammaglobulinemia. The evidence suggests that in individuals with atypical pneumonia and joint effusions, M pneumoniae should be considered as a source of infection.
Assuntos
Artrite/microbiologia , Mycoplasma pneumoniae/isolamento & purificação , Pneumonia por Mycoplasma/microbiologia , Líquido Sinovial/microbiologia , Feminino , Humanos , Articulação do Joelho , Pessoa de Meia-Idade , Articulação do PunhoRESUMO
Variable surface glycoprotein (VSG) genes in African trypanosomes are often activated by the duplicative transposition of a silent basic copy (BC) gene into an unlinked telomerically located expression site, producing an active expression-linked copy (ELC) of that gene. However, some BC genes that are already linked to a telomere are activated without apparent duplication or transposition. We have recently shown that an active VSG ELC can be inactivated in situ, apparently without rearrangement. To explain these observations it has been suggested that VSG genes that are associated with chromosome telomeres are activated by chromosome end exchanges that occur at a considerable distance upstream from the genes themselves and place them cis to a unique VSG expression element. In an attempt to test this model we derived five VSG-1 expressing variants from BoTat-2, a VSG-2 expressing variant of Trypanosoma equiperdum which carries an inactive residual VSG-1 ELC (R-ELC) as well as the active VSG-2 ELC near unlinked chromosome telomeres. We examined the fates of the VSG-2 ELC and the VSG-1 R-ELC in these variants. All five had maintained the VSG-1 R-ELC; three in a reactivated form and two in an inactive state. The latter two variants carried new, active VSG-1 ELCs: one in the site that had previously contained the VSG-2 ELC and one in a previously unidentified site. The VSG-2 ELC was lost in all five of the variants. The results are not consistent with the simple chromosome end exchange model, which predicts that the VSG-2 ELC would be inactivated but not deleted when the VSG-1 R-ELC was reactivated.
Assuntos
Antígenos de Protozoários/genética , Antígenos de Superfície/genética , Glicoproteínas/genética , Trypanosoma/genética , Animais , Deleção Cromossômica , Mapeamento Cromossômico , Regulação da Expressão Gênica , Proteínas de Membrana/genética , Glicoproteínas Variantes de Superfície de TrypanosomaRESUMO
Although Pneumocystis carinii is the most common opportunistic pathogen infecting individuals with AIDS, very little is known of the basic biology of the organism. We have examined the ribosomal RNA (rRNA) and the DNA encoding it (rDNA) in P. carinii in an attempt to clarify its taxonomic position and to begin to study its genetic processes. Electrophoretic analysis showed that the sizes of the P. carinii rRNAs are quite similar to the sizes of the corresponding rRNAs from Saccharomyces cerevisiae. Direct sequence analysis of approx. 60% of the 18S small subunit-rRNA (Ss-rRNA) confirmed that its sequence is similar to that of yeast-like fungi and that a putative group-I intron previously observed in the 18S rDNA is, in fact, excised from the mature rRNA. PCR analysis of the intron in P. carinii genomic DNA showed that each of the multiple rDNA genes bears the group-I intron and in vitro transcripts of the intron autocatalytically excise from the rRNA primary transcript in the presence of GTP. Finally, analogues of GTP inhibit the self-splicing reaction, indicating that the guanosine-binding site of the intron closely resembles that of other well-characterized group-I introns. Since no group-I introns have been found in higher eukaryotes, this self-splicing process represents a viable target for chemotherapy of P. carinii pneumonia (PCP).
Assuntos
Íntrons , Pneumocystis/genética , Splicing de RNA , RNA Ribossômico/genética , Transcrição Gênica , Antifúngicos/farmacologia , Sequência de Bases , Ligação Competitiva , Clonagem Molecular , DNA Fúngico , Guanosina/metabolismo , Dados de Sequência Molecular , Conformação de Ácido Nucleico , Reação em Cadeia da Polimerase , RNA Fúngico/química , RNA Fúngico/genética , RNA Ribossômico 18S/genética , RNA Ribossômico 5,8S/genética , RNA Ribossômico 5S/genéticaRESUMO
Trypanosome mRNA is processed to maturity in a novel trans-splicing reaction during which a 35-nucleotide (nt) spliced leader (SL) is joined to the 5' ends of most structural gene transcripts. We have examined this process in Trypanosoma cruzi, the causative agent of Chagas' disease in Central and South America. In this communication, we characterize the genes encoding the SL (SL gene) in five different strains of T. cruzi by hybridization analysis and show that the genome of each of these strains contains numerous tandemly repeated copies of the SL gene. We demonstrate that the SL genes show remarkable intrastrain homogeneity, but significant interstrain heterogeneity. We have cloned and sequenced one of the SL repeats from T. cruzi strain CL and used synthetic oligodeoxyribonucleotides designed to hybridize to SL gene transcripts in Northern analyses of T. cruzi RNA to identify an approx. 110-nt putative SL primary transcript (SL-RNA). The 5' end of the SL-RNA was mapped to the first nt of the SL by primer extension analyses. The sequence of the 110-nt SL-RNA was used to generate a predicted secondary structure, and this structure compared favorably to the predicted secondary structures of SL transcripts of other trypanosomatids.
Assuntos
Splicing de RNA , RNA Mensageiro/genética , Trypanosoma cruzi/genética , Animais , Sequência de Bases , Caenorhabditis/genética , Genes , Dados de Sequência Molecular , Conformação de Ácido Nucleico , RNA Mensageiro/metabolismo , Sequências Repetitivas de Ácido Nucleico , Homologia de Sequência do Ácido Nucleico , Especificidade da Espécie , Trypanosoma/genética , Trypanosoma cruzi/crescimento & desenvolvimentoRESUMO
A putative promoter element responsible for transcription of the spliced leader (SL) gene of Trypanosoma cruzi was identified by overlapping deletion and linker scanning analyses of the upstream flanking sequences using the bacterial chloramphenicol acetyltransferase (CAT) gene as a reporter in transient transfections of cultured epimastigotes. Deletion or substitution of a proximal sequence element (PSE) between positions -53 and -40 relative to the transcription start point eliminated CAT gene expression. Comparison of SL genes from several strains of T. cruzi revealed two alternative sequence patterns for the putative SL PSE, both composed of a short run of purines followed by a run of pyrimidines. Moreover, an examination of these sequences supports the subdivision of T. cruzi isolates into two divergent groups. Double-stranded oligonucleotides containing the sequence of the PSE exhibited specific gel mobility shifts after incubation with T. cruzi nuclear extracts, suggesting that a transcription factor binds this site. Finally, experiments designed to increase the level of CAT expression from the SL promoter suggest that it is not a strong promoter in cultured T. cruzi epimastigotes.
Assuntos
Genes de Protozoários , Regiões Promotoras Genéticas , Splicing de RNA , Transcrição Gênica , Trypanosoma cruzi/genética , Animais , Sequência de Bases , DNA de Protozoário , Dados de Sequência Molecular , RNA Mensageiro/genética , RNA de Protozoário/genética , Fatores de Transcrição , Trypanosomatina/genéticaRESUMO
The increasing success of intensive consolidation chemotherapy (CCT) as an alternative to bone marrow transplant (BMT) in acute myeloid leukaemia (AML) necessitates comparison of the impact on quality of life (QoL) of these two treatment modalities. Most QoL studies following BMT involve small patient numbers and provide ambivalent results. The present study examines QoL in a large number of patients 1 year from the end of treatment within the United Kingdom Medical Research Council (UK MRC) AML10 trial of BMT versus CCT. Allogeneic-BMT (Allo-BMT) was observed to have an adverse impact on most QoL dimensions compared with Autologous-BMT (A-BMT) and CCT. More patients receiving BMT had mouth dryness problems and worse sexual and social relationships, professional and leisure activities than CCT patients. QoL in A-BMT patients was less impacted than Allo-BMT. Intention-to-treat analysis showed similar results. These results indicate that a reconsideration of treatment strategies is warranted, and that further, good prospective studies are needed to evaluate more clearly the effects of these treatments in long-term survivors.
Assuntos
Transplante de Medula Óssea/efeitos adversos , Leucemia Mieloide Aguda/terapia , Qualidade de Vida , Adolescente , Adulto , Idoso , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Transtornos Cognitivos/etiologia , Efeitos Psicossociais da Doença , Fadiga/etiologia , Feminino , Doença Enxerto-Hospedeiro/etiologia , Humanos , Masculino , Pessoa de Meia-Idade , Inquéritos e Questionários , Transplante HomólogoRESUMO
We have constructed a plasmid vector system into which a segment of the Trypanosoma cruzi gene encoding the spliced leader (SL) has been inserted to drive expression of a downstream gene encoding bacterial chloramphenicol acetyltransferase (CAT). We used this construct to establish conditions that permit reproducible transfection of cultured T. cruzi epimastigotes where transfection was mediated by electroporation and measured by assaying expression of CAT. CAT activity was detected only in T. cruzi lysates from cells transfected with constructs containing a properly oriented SL gene; constructs in which the gene was inserted in reverse orientation did not express CAT. The optimal electric field strength, cell density and DNA concentration for efficient transfection were established. This and similar systems will permit genetic dissection of this parasite.
Assuntos
DNA de Protozoário/genética , Expressão Gênica , Transfecção , Trypanosoma cruzi/genética , Animais , Cloranfenicol O-Acetiltransferase/biossíntese , Cloranfenicol O-Acetiltransferase/genética , Vetores Genéticos , Plasmídeos , Regiões Promotoras GenéticasRESUMO
We have previously identified a major proximal sequence element (PSE) responsible for transcription of the spliced leader (SL) gene from Trypanosoma cruzi strain CL, and showed that the sequence encompassing this PSE exhibits approximately 30% divergence between two major groups of T. cruzi isolates, but strong conservation within the groups. In this report, we show that the SL RNA gene promoter from the CL strain (group I) is efficiently expressed only in T. cruzi isolates from group I. Similarly, the sequence of the approximately 643 bp promoter region of the T. cruzi rRNA is strongly conserved within, but diverged approximately 20% between, the two groups. Reporter constructs driven by the rRNA promoter sequences from group I strains are strongly expressed after electroporation into other group I strains, but not expressed in group II strains. In contrast, constructs bearing rRNA promoter sequences from group II strains are active in strains from both groups. Phylogenetic analyses performed with both the rRNA and the SL RNA gene promoter sequences yielded similar trees, and these trees strongly reinforce the partitioning of known T. cruzi into two major groups that parallel the observed functional specificity of the promoters. Given the well-documented species specific pattern of both rRNA promoters and PSEs in higher eukaryotes, these results suggest an ancient evolutionary divergence among organisms currently classified as T. cruzi.
Assuntos
Genes de Protozoários/genética , Conformação de Ácido Nucleico , Regiões Promotoras Genéticas/fisiologia , RNA Mensageiro/química , RNA Mensageiro/fisiologia , RNA Ribossômico/química , RNA Ribossômico/genética , Trypanosoma cruzi/genética , Animais , Sequência de Bases , Evolução Molecular , Dados de Sequência Molecular , Filogenia , Regiões Promotoras Genéticas/genética , Splicing de RNA , RNA Mensageiro/genética , RNA Ribossômico/fisiologia , Análise de Sequência de DNA , Homologia de Sequência do Ácido Nucleico , Trypanosoma cruzi/química , Trypanosoma cruzi/classificaçãoRESUMO
Nuclear mRNAs in trypanosomatids are generated by trans-splicing. Although trans-splicing resembles cis-splicing in many ways and most of the U RNA participants have been characterized, relatively few involved proteins have been identified. Herein, we employed a yeast three-hybrid system to identify a protein, XB1, which binds to the Trypanosoma cruzi SL RNA. XB1 is a approximately 45 kDa protein which is homologous to the essential pre-mRNA-splicing factor PRP31p from Saccharomyces cerevisiae. Gel shift assays and UV cross-linking experiments with recombinant XB1 confirmed that this T. cruzi protein binds the SL RNA in vitro. The binding site of XB1 on the SL RNA was mapped to stem-loop II by deletion of the SL RNA 'bait' in the three-hybrid system. Finally, UV cross-linking SL RNA with S100 extract indicated native XB1 protein and SL RNA interaction in T. cruzi extract.
Assuntos
RNA Líder para Processamento/metabolismo , Proteínas de Ligação a RNA/química , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/metabolismo , Trans-Splicing , Trypanosoma cruzi/metabolismo , Sequência de Aminoácidos , Animais , Sequência de Bases , Dados de Sequência Molecular , Proteínas de Protozoários/química , Proteínas de Protozoários/genética , Proteínas de Protozoários/metabolismo , RNA de Protozoário/genética , RNA de Protozoário/metabolismo , RNA Líder para Processamento/genética , Análise de Sequência de DNA , Ativação Transcricional , Trypanosoma cruzi/genética , Trypanosoma cruzi/crescimento & desenvolvimento , Técnicas do Sistema de Duplo-HíbridoRESUMO
In trypanosomatids, the spliced leader RNA, or SL RNA, donates its 5' 39 nucleotides to mature nuclear mRNAs in a process termed trans-splicing. We have previously characterized the SL RNA gene from Trypanosoma cruzi and identified its transcription promoter, including a 14 nt proximal sequence element, or PSE, that binds a putative transcription factor and activates transcription of the gene. Herein, we describe establishment of a yeast one-hybrid system using the 14 nt PSE as bait, and use this system to select T. cruzi cDNAs encoding a putative transcription factor that activates transcription of the SL RNA gene. The cDNA was selected from a normalized library and encodes an approximately 45 kDa putative PSE promoter-binding protein, PPB1. PPB1 in vitro translated or overexpressed in and isolated from transformed E. coli, showed PSE-specific binding activity by electrophoretic mobility shift assays. Finally, overexpression of PPB1 in T. cruzi led to increased expression of the SL RNA gene as well as reporter genes in episomal constructs under the control of the SL RNA gene promoter. These observations suggest that PPB1 is a transcription factor that plays an important role in SL RNA gene expression.
Assuntos
Proteínas de Ligação a DNA/metabolismo , Regulação da Expressão Gênica , RNA Líder para Processamento/metabolismo , Fatores de Transcrição/metabolismo , Trypanosoma cruzi/genética , Trypanosoma cruzi/metabolismo , Sequência de Aminoácidos , Animais , Sequência de Bases , DNA Complementar , Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/genética , Dados de Sequência Molecular , Regiões Promotoras Genéticas , Proteínas de Protozoários/genética , Proteínas de Protozoários/metabolismo , RNA Líder para Processamento/genética , Fatores de Transcrição/química , Fatores de Transcrição/genética , Transcrição Gênica , Trypanosoma cruzi/crescimento & desenvolvimento , Técnicas do Sistema de Duplo-HíbridoRESUMO
Plasmid constructs containing a putative Trypanosoma cruzi rRNA promoter and transcription start point upstream from the bacterial chloramphenicol acetyltransferase (CAT) reporter gene were transfected into cultured T. cruzi epimastigotes to verify the presence of a promoter activity. Constructs bearing the putative promoter and a 3' trans-splicing acceptor site in the proper orientation yielded approx. two orders of magnitude greater CAT expression than that previously observed with the T. cruzi spliced leader (SL) gene promoter. In contrast, similar constructs lacking the known 3' splice site yielded reduced but readily measurable expression suggesting that sequences near the promoter may function as cryptic 3' splice sites. A repeated sequence upstream from the putative basal rRNA promoter in a position analogous to rRNA gene enhancer elements in other eukaryotes did not enhance expression from the T. cruzi rRNA promoter. Finally, these constructs were functional in some but not all T. cruzi isolates, and were inactive in other kinetoplastid species, suggesting that the T. cruzi rRNA promoter may have a limited host range.