RESUMO
Transcription termination by RNA polymerase II (RNA Pol II) is linked to RNA 3' end processing by the cleavage and polyadenylation factor (CPF or CPSF). CPF contains endonuclease, poly(A) polymerase, and protein phosphatase activities, which cleave and polyadenylate pre-mRNAs and dephosphorylate RNA Pol II to control transcription. Exactly how the RNA 3' end processing machinery is coupled to transcription remains unclear. Here, we combine in vitro reconstitution, structural studies, and genome-wide analyses to show that yeast CPF physically and functionally interacts with RNA Pol II. Surprisingly, CPF-mediated dephosphorylation promotes the formation of an RNA Pol II stalk-to-stalk homodimer in vitro. This dimer is compatible with transcription but not with the binding of transcription elongation factors. Disruption of the dimerization interface in cells causes transcription defects, including altered RNA Pol II abundance on protein-coding genes, tRNA genes, and intergenic regions. We hypothesize that RNA Pol II dimerization may provide a mechanistic basis for the allosteric model of transcription termination.
Assuntos
RNA Polimerase II , Proteínas de Saccharomyces cerevisiae , RNA Polimerase II/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Estudo de Associação Genômica Ampla , Transcrição Gênica , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Processamento de Terminações 3' de RNA/genéticaRESUMO
Gene expression is controlled in a dynamic and regulated manner to allow for the consistent and steady expression of some proteins as well as the rapidly changing production of other proteins. Transcription initiation has been a major focus of study because it is highly regulated. However, termination of transcription also plays an important role in controlling gene expression. Transcription termination on protein-coding genes is intimately linked with 3' end cleavage and polyadenylation of transcripts, and it generally results in the production of a mature mRNA that is exported from the nucleus. Termination on many non-coding genes can also result in the production of a mature transcript. Termination is dynamically regulated-premature termination and transcription readthrough occur in response to a number of cellular signals, and these can have varied consequences on gene expression. Here, we review eukaryotic transcription termination by RNA polymerase II (RNAPII), focusing on protein-coding genes.
Assuntos
RNA Polimerase II , Transcrição Gênica , RNA Polimerase II/genética , RNA Polimerase II/metabolismo , Poliadenilação , RNA Mensageiro/genética , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Terminação da Transcrição GenéticaRESUMO
During their synthesis in the cell nucleus, most eukaryotic mRNAs undergo a two-step 3'-end processing reaction in which the pre-mRNA is cleaved and released from the transcribing RNA polymerase II and a polyadenosine (poly(A)) tail is added to the newly formed 3'-end. These biochemical reactions might appear simple at first sight (endonucleolytic RNA cleavage and synthesis of a homopolymeric tail), but their catalysis requires a multi-faceted enzymatic machinery, the cleavage and polyadenylation complex (CPAC), which is composed of more than 20 individual protein subunits. The activity of CPAC is further orchestrated by Poly(A) Binding Proteins (PABPs), which decorate the poly(A) tail during its synthesis and guide the mRNA through subsequent gene expression steps. Here, we review the structure, molecular mechanism, and regulation of eukaryotic mRNA 3'-end processing machineries with a focus on the polyadenylation step. We concentrate on the CPAC and PABPs from mammals and the budding yeast, Saccharomyces cerevisiae, because these systems are the best-characterized at present. Comparison of their functions provides valuable insights into the principles of mRNA 3'-end processing.
Assuntos
Poliadenilação , Proteínas de Saccharomyces cerevisiae , Animais , Poliadenilação/genética , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Núcleo Celular/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Mamíferos/genéticaRESUMO
Most eukaryotic messenger RNAs (mRNAs) are processed at their 3' end by the cleavage and polyadenylation specificity factor (CPF/CPSF). CPF mediates the endonucleolytic cleavage of the pre-mRNA and addition of a polyadenosine (poly(A)) tail, which together define the 3' end of the mature transcript. The activation of CPF is highly regulated to maintain the fidelity of RNA processing. Here, using cryo-EM of yeast CPF, we show that the Mpe1 subunit directly contacts the polyadenylation signal sequence in nascent pre-mRNA. The region of Mpe1 that contacts RNA also promotes the activation of CPF endonuclease activity and controls polyadenylation. The Cft2 subunit of CPF antagonizes the RNA-stabilized configuration of Mpe1. In vivo, the depletion or mutation of Mpe1 leads to widespread defects in transcription termination by RNA polymerase II, resulting in transcription interference on neighboring genes. Together, our data suggest that Mpe1 plays a major role in accurate 3' end processing, activating CPF, and ensuring timely transcription termination.
Assuntos
Precursores de RNA , Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae , Fatores de Poliadenilação e Clivagem de mRNA , Sequência de Aminoácidos , Microscopia Crioeletrônica , Poliadenilação , Ligação Proteica , Estrutura Terciária de Proteína , Precursores de RNA/genética , RNA Mensageiro/genética , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Fatores de Poliadenilação e Clivagem de mRNA/genética , Fatores de Poliadenilação e Clivagem de mRNA/metabolismoRESUMO
Cleavage and polyadenylation factor (CPF/CPSF) is a multiprotein complex essential for mRNA 3' end processing in eukaryotes. It contains an endonuclease that cleaves pre-mRNAs, and a polymerase that adds a poly(A) tail onto the cleaved 3' end. Several CPF subunits, including Fip1, contain intrinsically disordered regions (IDRs). IDRs within multiprotein complexes can be flexible, or can become ordered upon interaction with binding partners. Here, we show that yeast Fip1 anchors the poly(A) polymerase Pap1 onto CPF via an interaction with zinc finger 4 of another CPF subunit, Yth1. We also reconstitute a fully recombinant 850-kDa CPF. By incorporating selectively labeled Fip1 into recombinant CPF, we could study the dynamics of Fip1 within the megadalton complex using nuclear magnetic resonance (NMR) spectroscopy. This reveals that a Fip1 IDR that connects the Yth1- and Pap1-binding sites remains highly dynamic within CPF. Together, our data suggest that Fip1 dynamics within the 3' end processing machinery are required to coordinate cleavage and polyadenylation.
Assuntos
Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae , Poliadenilação , Precursores de RNA/metabolismo , RNA Mensageiro/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Fatores de Poliadenilação e Clivagem de mRNA/genética , Fatores de Poliadenilação e Clivagem de mRNA/metabolismoRESUMO
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
RESUMO
The post-genomic era has seen many advances in our understanding of cancer pathways, yet resistance and tumor heterogeneity necessitate multiple approaches to target even monogenic tumors. Here, we combine phenotypic screening with chemical genetics to identify pre-messenger RNA endonuclease cleavage and polyadenylation specificity factor 3 (CPSF3) as the target of JTE-607, a small molecule with previously unknown target. We show that CPSF3 represents a synthetic lethal node in a subset of acute myeloid leukemia (AML) and Ewing's sarcoma cancer cell lines. Inhibition of CPSF3 by JTE-607 alters expression of known downstream effectors in AML and Ewing's sarcoma lines, upregulates apoptosis and causes tumor-selective stasis in mouse xenografts. Mechanistically, it prevents the release of newly synthesized pre-mRNAs, resulting in read-through transcription and the formation of DNA-RNA hybrid R-loop structures. This study implicates pre-mRNA processing, and specifically CPSF3, as a druggable target providing an avenue to therapeutic intervention in cancer.
Assuntos
Fator de Especificidade de Clivagem e Poliadenilação/metabolismo , Leucemia Mieloide Aguda/metabolismo , Precursores de RNA/metabolismo , Sarcoma de Ewing/metabolismo , Animais , Apoptose/efeitos dos fármacos , Sítios de Ligação , Hidrolases de Éster Carboxílico/metabolismo , Linhagem Celular Tumoral , Sobrevivência Celular , Fator de Especificidade de Clivagem e Poliadenilação/genética , Células HEK293 , Humanos , Leucemia Mieloide Aguda/tratamento farmacológico , Masculino , Espectrometria de Massas , Camundongos , Camundongos Endogâmicos C57BL , Transplante de Neoplasias , Fenótipo , Fenilalanina/análogos & derivados , Fenilalanina/farmacologia , Piperazinas/farmacologia , Ligação Proteica , RNA Mensageiro/metabolismo , RNA Interferente Pequeno/metabolismo , Sarcoma de Ewing/tratamento farmacológicoRESUMO
The 3'-ends of eukaryotic pre-mRNAs are processed in the nucleus by a large multiprotein complex, the cleavage and polyadenylation factor (CPF). CPF cleaves RNA, adds a poly(A) tail and signals transcription termination. CPF harbors four enzymatic activities essential for these processes, but how these are coordinated remains poorly understood. Several subunits of CPF, including two protein phosphatases, are also found in the related 'associated with Pta1' (APT) complex, but the relationship between CPF and APT is unclear. Here, we show that the APT complex is physically distinct from CPF. The 21 kDa Syc1 protein is associated only with APT, and not with CPF, and is therefore the defining subunit of APT. Using ChIP-seq, PAR-CLIP and RNA-seq, we show that Syc1/APT has distinct, but possibly overlapping, functions from those of CPF. Syc1/APT plays a more important role in sn/snoRNA production whereas CPF processes the 3'-ends of protein-coding pre-mRNAs. These results define distinct protein machineries for synthesis of mature eukaryotic protein-coding and non-coding RNAs.
Assuntos
Complexos Multiproteicos/metabolismo , RNA não Traduzido/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Transcrição Gênica , Fatores de Poliadenilação e Clivagem de mRNA/metabolismo , Imunoprecipitação da Cromatina , Complexos Multiproteicos/genética , Subunidades Proteicas , RNA Nucleolar Pequeno/genética , RNA Nucleolar Pequeno/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Fatores de Poliadenilação e Clivagem de mRNA/genéticaRESUMO
BACKGROUND: New biomarkers are necessary to improve detection of the risk of infection in heart transplantation. We performed a multicenter study to evaluate humoral immunity profiles that could better enable us to identify heart recipients at risk of severe infections. METHODS: We prospectively analyzed 170 adult heart recipients at 8 centers in Spain. Study points were before transplantation and 7 and 30 days after transplantation. Immune parameters included IgG, IgM, IgA and complement factors C3 and C4, and titers of specific antibody to pneumococcal polysaccharide antigens (anti-PPS) and to cytomegalovirus (CMV). To evaluate potential immunologic mechanisms leading to IgG hypogammaglobulinemia, before heart transplantation we assessed serum B-cell activating factor (BAFF) levels using enzyme-linked immunoassay. The clinical follow-up period lasted 6 months. Clinical outcome was need for intravenous anti-microbials for therapy of infection. RESULTS: During follow-up, 53 patients (31.2%) developed at least 1 severe infection. We confirmed that IgG hypogammaglobulinemia at Day 7 (defined as IgG <600 mg/dl) is a risk factor for infection in general, bacterial infections in particular, and CMV disease. At Day 7 after transplantation, the combination of IgG <600 mg/dl + C3 <80 mg/dl was more strongly associated with the outcome (adjusted odds ratio 7.40; 95% confidence interval 1.48 to 37.03; p = 0.014). We found that quantification of anti-CMV antibody titers and lower anti-PPS antibody concentrations were independent predictors of CMV disease and bacterial infections, respectively. Higher pre-transplant BAFF levels were a risk factor of acute cellular rejection. CONCLUSION: Early immunologic monitoring of humoral immunity profiles proved useful for the identification of heart recipients who are at risk of severe infection.
Assuntos
Infecções por Citomegalovirus/epidemiologia , Transplante de Coração/efeitos adversos , Imunidade Humoral/fisiologia , Imunoglobulinas/sangue , Complicações Pós-Operatórias/diagnóstico , Adulto , Fator Ativador de Células B/sangue , Infecções Bacterianas/epidemiologia , Infecções Bacterianas/fisiopatologia , Biomarcadores/sangue , Estudos de Coortes , Complemento C3/metabolismo , Complemento C4/metabolismo , Infecções por Citomegalovirus/etiologia , Infecções por Citomegalovirus/fisiopatologia , Feminino , Rejeição de Enxerto/imunologia , Transplante de Coração/métodos , Humanos , Imunoglobulinas/imunologia , Incidência , Estimativa de Kaplan-Meier , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Monitorização Imunológica/métodos , Análise Multivariada , Complicações Pós-Operatórias/sangue , Prognóstico , Estudos Prospectivos , Curva ROC , Medição de Risco , Espanha , Viroses/epidemiologia , Viroses/fisiopatologiaRESUMO
During transcription initiation, the TFIIH-kinase Kin28/Cdk7 marks RNA polymerase II (Pol II) by phosphorylating the C-terminal domain (CTD) of its largest subunit. Here we describe a structure-guided chemical approach to covalently and specifically inactivate Kin28 kinase activity in vivo. This method of irreversible inactivation recapitulates both the lethal phenotype and the key molecular signatures that result from genetically disrupting Kin28 function in vivo. Inactivating Kin28 impacts promoter release to differing degrees and reveals a "checkpoint" during the transition to productive elongation. While promoter-proximal pausing is not observed in budding yeast, inhibition of Kin28 attenuates elongation-licensing signals, resulting in Pol II accumulation at the +2 nucleosome and reduced transition to productive elongation. Furthermore, upon inhibition, global stabilization of mRNA masks different degrees of reduction in nascent transcription. This study resolves long-standing controversies on the role of Kin28 in transcription and provides a rational approach to irreversibly inhibit other kinases in vivo.
Assuntos
Quinases Ciclina-Dependentes/metabolismo , Engenharia de Proteínas , Estabilidade de RNA , RNA Fúngico/metabolismo , RNA Mensageiro/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/enzimologia , Elongação da Transcrição Genética , Quinases Ciclina-Dependentes/antagonistas & inibidores , Quinases Ciclina-Dependentes/química , Quinases Ciclina-Dependentes/genética , DNA Polimerase II/genética , DNA Polimerase II/metabolismo , Humanos , Modelos Moleculares , Mutação , Nucleossomos/enzimologia , Nucleossomos/genética , Fosforilação , Regiões Promotoras Genéticas , Conformação Proteica , Inibidores de Proteínas Quinases/farmacologia , Estabilidade de RNA/efeitos dos fármacos , RNA Fúngico/efeitos dos fármacos , RNA Fúngico/genética , RNA Mensageiro/efeitos dos fármacos , RNA Mensageiro/genética , Saccharomyces cerevisiae/efeitos dos fármacos , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/crescimento & desenvolvimento , Proteínas de Saccharomyces cerevisiae/antagonistas & inibidores , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/genética , Relação Estrutura-Atividade , Fatores de Tempo , Elongação da Transcrição Genética/efeitos dos fármacos , Quinase Ativadora de Quinase Dependente de CiclinaRESUMO
The C-terminal domain (CTD) of RNA polymerase II (Pol II) consists of conserved heptapeptide repeats that function as a binding platform for different protein complexes involved in transcription, RNA processing, export, and chromatin remodeling. The CTD repeats are subject to sequential waves of posttranslational modifications during specific stages of the transcription cycle. These patterned modifications have led to the postulation of the "CTD code" hypothesis, where stage-specific patterns define a spatiotemporal code that is recognized by the appropriate interacting partners. Here, we highlight the role of CTD modifications in directing transcription initiation, elongation, and termination. We examine the major readers, writers, and erasers of the CTD code and examine the relevance of describing patterns of posttranslational modifications as a "code." Finally, we discuss major questions regarding the function of the newly discovered CTD modifications and the fundamental insights into transcription regulation that will necessarily emerge upon addressing those challenges.
RESUMO
The C-terminal domain (CTD) of the largest subunit of RNA polymerase II (Pol II) serves an important role in coordinating stage-specific recruitment and release of cellular machines during transcription. Dynamic placement and removal of phosphorylation marks on different residues of a repeating heptapeptide (YSPTSPS) of the CTD underlies the engagement of relevant cellular machinery. Whereas sequential placement of phosphorylation marks is well explored, genome-wide engagement of phosphatases that remove these CTD marks is poorly understood. In particular, identifying the enzyme that erases phospho-Ser7 (Ser7-P) marks is especially important, because we find that substituting this residue with a glutamate, a phospho-mimic, is lethal. Our observations implicate Ssu72 as a Ser7-P phosphatase. We report that removal of all phospho-CTD marks during transcription termination is mechanistically coupled. An inability to remove these marks prevents Pol II from terminating efficiently and will likely impede subsequent assembly into the pre-initiation complex.
Assuntos
Fosfoproteínas Fosfatases/metabolismo , RNA Polimerase II/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/metabolismo , Fatores de Poliadenilação e Clivagem de mRNA/metabolismo , Motivos de Aminoácidos , Substituição de Aminoácidos , Mutação de Sentido Incorreto , Fosfoproteínas Fosfatases/genética , Estrutura Terciária de Proteína , RNA Polimerase II/genética , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/genética , Serina/genética , Serina/metabolismo , Transcrição Gênica , Fatores de Poliadenilação e Clivagem de mRNA/genéticaRESUMO
The Saccharomyces cerevisiae SEN1 gene codes for a nuclear, ATP-dependent helicase which is embedded in a complex network of protein-protein interactions. Pleiotropic phenotypes of mutations in SEN1 suggest that Sen1 functions in many nuclear processes, including transcription termination, DNA repair, and RNA processing. Sen1, along with termination factors Nrd1 and Nab3, is required for the termination of noncoding RNA transcripts, but Sen1 is associated during transcription with coding and noncoding genes. Sen1 and Nrd1 both interact directly with Nab3, as well as with the C-terminal domain (CTD) of Rpb1, the largest subunit of RNA polymerase II. It has been proposed that Sen1, Nab3, and Nrd1 form a complex that associates with Rpb1 through an interaction between Nrd1 and the Ser5-phosphorylated (Ser5-P) CTD. To further study the relationship between the termination factors and Rpb1, we used two-hybrid analysis and immunoprecipitation to characterize sen1-R302W, a mutation that impairs an interaction between Sen1 and the Ser2-phosphorylated CTD. Chromatin immunoprecipitation indicates that the impairment of the interaction between Sen1 and Ser2-P causes the reduced occupancy of mutant Sen1 across the entire length of noncoding genes. For protein-coding genes, mutant Sen1 occupancy is reduced early and late in transcription but is similar to that of the wild type across most of the coding region. The combined data suggest a handoff model in which proteins differentially transfer from the Ser5- to the Ser2-phosphorylated CTD to promote the termination of noncoding transcripts or other cotranscriptional events for protein-coding genes.
Assuntos
DNA Helicases/metabolismo , Proteínas Nucleares/metabolismo , RNA Helicases/metabolismo , Proteínas de Ligação a RNA/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/metabolismo , Substituição de Aminoácidos , DNA Helicases/genética , DNA Helicases/isolamento & purificação , Regulação Fúngica da Expressão Gênica , Complexos Multiproteicos/isolamento & purificação , Complexos Multiproteicos/metabolismo , Proteínas Nucleares/isolamento & purificação , Fosfoproteínas/metabolismo , Fosforilação , Ligação Proteica , Domínios e Motivos de Interação entre Proteínas , RNA Helicases/genética , RNA Helicases/isolamento & purificação , Proteínas de Ligação a RNA/química , Proteínas de Ligação a RNA/isolamento & purificação , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/isolamento & purificação , Transcrição Gênica , Técnicas do Sistema de Duplo-HíbridoRESUMO
Sequential modifications of the RNA polymerase II (Pol II) C-terminal domain (CTD) coordinate the stage-specific association and release of cellular machines during transcription. Here we examine the genome-wide distributions of the 'early' (phospho-Ser5 (Ser5-P)), 'mid' (Ser7-P) and 'late' (Ser2-P) CTD marks. We identify gene class-specific patterns and find widespread co-occurrence of the CTD marks. Contrary to its role in 3'-processing of noncoding RNA, the Ser7-P marks are placed early and retained until transcription termination at all Pol II-dependent genes. Chemical-genomic analysis reveals that the promoter-distal Ser7-P marks are not remnants of early phosphorylation but are placed anew by the CTD kinase Bur1. Consistent with the ability of Bur1 to facilitate transcription elongation and suppress cryptic transcription, high levels of Ser7-P are observed at highly transcribed genes. We propose that Ser7-P could facilitate elongation and suppress cryptic transcription.
Assuntos
Genoma , Família Multigênica , Fases de Leitura Aberta , Fosforilação , Proteínas Serina-Treonina Quinases/metabolismo , RNA Polimerase II/metabolismo , RNA não Traduzido , Especificidade por Substrato , Transcrição GênicaRESUMO
We sought to determine whether quantitative assessment of anti-cytomegalovirus (CMV) antibodies could be useful to identify patients at risk of cytomegalovirus (CMV) disease after heart transplantation (HT). 75 patients who underwent HT at a single health care center were prospectively studied. Induction therapy included 2 doses of daclizumab and maintenance tacrolimus (n=42) or cyclosporine (n=29), mycophenolate mofetil and prednisone. All patients received prophylaxis with gancyclovir or valganciclovir. Anti-CMV intravenous immunoglobulin (CMV-IG) was added in high risk patients (CMV D+/R- serostatus). Serial determinations of anti-CMV antibodies, immunoglobulins (IgG, IgA, IgM) and IgG-subclasses were analysed. CMV infection was based on detection of the virus by antigenemia. CMV disease consisted of detection of signs or symptoms attributable to this microorganism. Ten patients (13.3%) developed CMV disease. Mean time of development of CMV disease was 3.4+/-1.6 months. In Cox regression analysis, patients with low baseline anti-CMV titers (<4.26 natural logarithm of titer, RH: 8.1, 95%CI: 1.93-34.1, p=0.004) and recipients with 1-month post-HT IgG hypogammaglobulinemia (IgG<500 mg/dl, RH: 4.49, 95%CI: 1.26-15.94, p=0.02) were at higher risk of having CMV disease. Despite use of prophylactic CMV-IG, D+/R- patients showed significantly lower titers of anti-CMV antibodies at 7 d, 30 d and 90 d post HT as compared with HT recipients without infections. Four out of 6 of these patients developed late CMV disease. Monitoring of specific anti-CMV antibodies on the bedside warrants further evaluation as a potential tool to identify heart transplant recipients at higher risk of CMV disease.
Assuntos
Anticorpos Antivirais/sangue , Infecções por Citomegalovirus/diagnóstico , Citomegalovirus/imunologia , Transplante de Coração/imunologia , Monitorização Imunológica , Adulto , Anticorpos Antivirais/imunologia , Anticorpos Antivirais/uso terapêutico , Antivirais/uso terapêutico , Estudos de Coortes , Feminino , Seguimentos , Humanos , Imunoglobulinas/sangue , Imunoglobulinas Intravenosas/uso terapêutico , Masculino , Pessoa de Meia-Idade , Modelos de Riscos Proporcionais , Estudos Prospectivos , Análise de RegressãoAssuntos
Artrite Reumatoide/imunologia , Autoanticorpos/sangue , Imunoglobulina G/sangue , Peptídeos Cíclicos/imunologia , Vimentina/imunologia , Adolescente , Adulto , Idade de Início , Idoso , Artrite Reumatoide/mortalidade , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Análise de SobrevidaRESUMO
Cryoglobulinemia may be found in up to 30% of patients that had received liver transplants after hepatitis C virus (HCV) cirrhosis. Three types of cryoglobulinemia are recognized: type I, composed of monoclonal immunoglobulins associated with lymphoproliferative diseases and myeloma; type II cryoglobulinemia are comprised of a monoclonal component which has rheumatoid factor activity and hence binds to polyclonal immunoglobulins (in certain parts of the world have been found to be associated with hepatitis C infection); and type III cryoglobulinemia consist exclusively of polyclonal immunoglobulins with rheumatoid factor activity (associated with connective tissue diseases and chronic infections including hepatitis C). Immunocompetence, autoimmunity and clonal expansion of B cell lymphocytes have not been analysed simultaneously in previous reports of patients with cryoglobulinemia after liver transplantation. We here describe immunological abnormalities associated with cryoglobulinemia in a patient who had received liver transplant for HCV cirrhosis. In addition, in the present work HCV RNA determination was performed directly in the cryocrit and not only in peripheral blood. We have observed enrichment of HCV RNA in the cryoprecipitates which might be a better demonstration of the possible role of HCV in the pathogenesis of the cryoglobulinemia.
Assuntos
Crioglobulinemia/imunologia , Hepatite C Crônica/complicações , Doenças do Sistema Imunitário/imunologia , Cirrose Hepática/virologia , Transplante de Fígado/efeitos adversos , Crioglobulinemia/diagnóstico , Crioglobulinemia/terapia , Evolução Fatal , Hepatite C Crônica/imunologia , Humanos , Doenças do Sistema Imunitário/diagnóstico , Doenças do Sistema Imunitário/terapia , Cirrose Hepática/cirurgia , Transplante de Fígado/imunologia , Masculino , Pessoa de Meia-Idade , Plasmaferese , Complicações Pós-OperatóriasRESUMO
BACKGROUND AND OBJECTIVE: The aim of this study was to evaluate the clinical and immunologic profile, the rate of progression to connective tissue disease and the possible predictors of evolution in patients with antiphospholipid antibodies and abortions. PATIENTS AND METHOD: In a prospective follow-up study, we determined the prevalence of antiphospholipid antibodies as well as other autoimmune abnormalities and the evolution to connective tissue disease in 200 women with unexplained recurrent abortions. IgG and IgM anticardiolipin antibodies were determined by ELISA and the lupus anticoagulant was determined by means of coagulometric tests. RESULTS: Of 200 women with pregnancy losses, 69 (34.5%) had antiphospholipid antibodies. Thirty-one of 200 women (15.5%) had high or moderate positive anticardiolipin antibodies. During a mean follow-up of 32 months, 9 (13%) antiphospholipid-antibody-positive patients developed features of lupus- like disease or systemic lupus erythematosus. A low total hemolytic complement, increased circulating immune complexes and positive antinuclear antibodies (ANA) were more common in those patients evolving to a connective tissue disorder (p < 0.001, p = 0.003 and p < 0.001, respectively). Positive ANA in women with antiphospholipid antibodies predicted independently the evolution to a connective tissue disorder [Cox proportional hazard model; relative hazard = 4.92, p = 0.04]. CONCLUSIONS: A subgroup of patients with antiphospholipid antibodies and abortions may progress to a connective tissue disorder. A positive antinuclear antibody test result could be useful to identify those patients with antiphospholipid antibodies and abortions who are prone to evolve into a systemic autoimmune disease.
Assuntos
Aborto Habitual/imunologia , Anticorpos Antifosfolipídeos/imunologia , Doenças do Tecido Conjuntivo/imunologia , Adulto , Progressão da Doença , Feminino , Seguimentos , Humanos , Pessoa de Meia-Idade , Gravidez , Estudos ProspectivosRESUMO
FUNDAMENTO Y OBJETIVO: El objetivo de este estudio fue la determinación del perfil clínico e inmunológico, la tasa de progresión a conectivopatía y posibles variables predictoras de evolución en pacientes con abortos y anticuerpos antifosfolipídicos. PACIENTES Y MÉTODO: Estudiamos prospectivamente la prevalencia de anticuerpos antifosfolipídicos, otras alteraciones autoinmunitarias y su evolución a conectivopatía en 200 mujeres con aborto recurrente. Los anticuerpos antifosfolipídicos se determinaron mediante técnica de enzimoinmunoanálisis (anticuerpos anticardiolipina IgG e IgM) y por técnicas coagulométricas (anticoagulante lúpico). RESULTADOS: De 200 mujeres con abortos, 69 (34,5 per cent) tuvieron anticuerpos antifosfolipídicos. Treinta y un pacientes (15,5 per cent) tenían anticuerpos anticardiolipina a título moderado-alto. Tras una media de seguimiento de 32 meses, 9 pacientes con anticuerpos antifosfolipídicos (13 per cent) evolucionaron a lupus eritematoso sistémico o a enfermedad lupus like. Se observaron con más frecuencia cifras bajas de complemento hemolítico total, concentraciones elevadas de inmunocomplejos circulantes y anticuerpos antinucleares positivos en las pacientes con anticuerpos antifosfolipídicos que evolucionaron a conectivopatía frente a las que no lo hicieron (p < 0,001, p = 0,003 y p < 0,001, respectivamente). La positividad de anticuerpos antinucleares en las pacientes con anticuerpos antifosfolipídicos predijo de forma independiente la evolución a conectivopatía mediante análisis de regresión de Cox (riesgo relativo = 4,92; p = 0,04).CONCLUSIONES: Un subgrupo de pacientes con abortos y anticuerpos antifosfolipídicos puede evolucionar a conectivopatía. La positividad de los anticuerpos antinucleares podría utilizarse para identificar a pacientes con abortos y anticuerpos antifosfolipídicos positivos que a lo largo de su evolución pueden presentar síntomas indicativos de evolución a conectivopatía sistémica (AU)