RESUMO
INTRODUCTION: Pregnancies in women with lupus nephritis are at high-risk of complications, while scarcity of scientific knowledge on prognostic factors impedes a fair medical counseling. We aimed to identify determinants associated with maternal and fetal complications. MATERIALS: We retrospectively reviewed medical charts of pregnancies that lasted more than 22 weeks in 66 patients with pre-existing lupus nephritis between 2004 and 2013 in France. Univariate and multivariate analyses were conducted to identify determinants for maternal complications, lupus renal flare and fetal prematurity or death. RESULTS: Eighty-four pregnancies were identified. A maternal complication occurred in 31 pregnancies (36.9%): mostly preeclampsia (17 pregnancies, 20.2%) and renal flares (12 pregnancies, 14.3%). Overall fetal survival was 94.0% (79/84). Maternal pregnancy complications were independently associated with prepregnancy body mass index >25 kg/m2 (OR 3.81, 95% CI 1.03-14.09) and immunological activity (positive anti-dsDNA antibodies or Farr assay lupus) (OR 4.95, 95% CI 1.33-18.43). Renal lupus flares were independently associated with maternal age (OR 1.50, 95% CI 1.12-2.01) and prepregnancy immunological activity (OR 15.99, 95% CI 1.57-162.68) while a remission time >12 months had a protective effect (OR 0.17, 95% CI 0.04-0.68). Three parameters were associated with a higher risk of fetal prematurity or death: a prepregnancy body mass index >25 kg/m2 (HR 3.58, 95% CI 1.45-8.83), hypertension (HR 8.97, 95% CI 3.32-24.25), and immunological activity (HR 3.34, 95% CI 1.30-8.63). CONCLUSION: Maternal age, prepregnancy hypertension, body mass index >25 kg/m2 and lupus immunological activity may be considered as the main determinants for fetal and maternal complications. A remission time above 12 months for patients with lupus nephritis could be associated with a reduced risk of renal flare during pregnancy.
Assuntos
Nefrite Lúpica/epidemiologia , Sobrepeso/epidemiologia , Pré-Eclâmpsia/epidemiologia , Complicações na Gravidez/epidemiologia , Resultado da Gravidez/epidemiologia , Adulto , Fatores Etários , Índice de Massa Corporal , Feminino , França/epidemiologia , Humanos , Hipertensão Renal/epidemiologia , Recém-Nascido , Recém-Nascido Prematuro , Estimativa de Kaplan-Meier , Nefrite Lúpica/imunologia , Idade Materna , Análise Multivariada , Morte Perinatal/etiologia , Gravidez , Prognóstico , Modelos de Riscos Proporcionais , Estudos Retrospectivos , Fatores de Risco , Natimorto/epidemiologia , Adulto JovemRESUMO
Objective To study the influence of Maghrebian ethnicity on lupus nephritis. Methods We retrospectively reviewed the files of a cohort of 194 patients with proliferative lupus nephritis followed in seven lupus centres belonging to three groups: Europeans living in Belgium/France (E; n = 111); Maghrebians living in Europe, in casu Belgium/France (ME; n = 43); and Maghrebians living in Morocco (MM; n = 40). Baseline presentation was compared between these three groups but complete long-term outcome data were available only for E and ME patients. Results At presentation, the clinical and pathological characteristics of lupus nephritis did not differ between E, ME and MM patients. Renal relapses were more common in ME patients (54%) than in E patients (29%) ( P < 0.01). Time to renal flare and to end-stage renal disease was shorter in ME patients compared to E patients ( P < 0.0001 and P < 0.05, respectively). While proteinuria measured at month 12 accurately predicted a serum creatinine value of less than 1 mg/dl at 7 years in E patients, this was not the case in the ME group, in whom serum creatinine at month 12 performed better. Conclusion Despite a similar disease profile at onset, the prognosis of lupus nephritis is more severe in Maghrebians living in Europe compared to native Europeans, with a higher relapse rate.
Assuntos
Imunossupressores/uso terapêutico , Falência Renal Crônica/mortalidade , Rim/patologia , Nefrite Lúpica/tratamento farmacológico , Proteinúria/etnologia , Adulto , África do Norte/etnologia , Creatinina/sangue , Europa (Continente) , Feminino , Taxa de Filtração Glomerular , Humanos , Estimativa de Kaplan-Meier , Falência Renal Crônica/etnologia , Nefrite Lúpica/complicações , Nefrite Lúpica/etnologia , Masculino , Pessoa de Meia-Idade , Curva ROC , Estudos Retrospectivos , Resultado do Tratamento , Adulto JovemRESUMO
We report the case of a 40-year-old woman who recovered from a diffuse metastatic renal cell carcinoma that developed from a kidney allograft. She was successfully treated by the induction of tumor rejection. Immunosuppression was discontinued, and transplant nephrectomy was deliberately delayed based on the expectation that the tumor mass would trigger the alloimmune response, which was stimulated with pegylated interferon-α-2a. Three years later, the patient remained in complete remission. Despite this severe context, the present case shows that the poor prognosis of allograft metastatic renal cell carcinoma could be dramatically reversed by taking advantage of the donor tumor origin to actively induce a specific alloimmune rejection of the tumor.
Assuntos
Carcinoma de Células Renais/tratamento farmacológico , Interferon-alfa/uso terapêutico , Neoplasias Renais/tratamento farmacológico , Transplante de Rim/efeitos adversos , Polietilenoglicóis/uso terapêutico , Adulto , Antivirais/uso terapêutico , Carcinoma de Células Renais/etiologia , Carcinoma de Células Renais/secundário , Feminino , Humanos , Neoplasias Renais/etiologia , Neoplasias Renais/patologia , Proteínas Recombinantes/uso terapêutico , Indução de Remissão , Transplante HomólogoRESUMO
PURPOSE: To develop French recommendations about the management of vaccinations, the screening of cervical cancer and the prevention of pneumocystis pneumonia in systemic lupus erythematosus (SLE). METHODS: Thirty-seven experts qualified in internal medicine, rheumatology, dermatology, nephrology and pediatrics have selected recommendations from a list of proposition based on available data from the literature. For each recommendation, the level of evidence and the level of agreement among the experts were specified. RESULTS: Inactivated vaccines do not cause significant harm in SLE patients. Experts recommend that lupus patient should receive vaccinations accordingly to the recommendations and the schedules for the general public. Pneumococcal vaccination is recommended for all SLE patients. Influenza vaccination is recommended for immunosuppressed SLE patients. Live attenuated vaccines should be avoided in immunosuppressed patients. Yet, recent works suggest that they can be considered in mildly immunosuppressed patients. Experts have recommended a cervical cytology every year for immunosuppressed patients. No consensus was obtained for the prevention of pneumocystis pneumonia. CONCLUSION: These recommendations can be expected to improve clinical practice uniformity and, in the longer term, to optimize the management of SLE patients.
Assuntos
Prova Pericial , Controle de Infecções/normas , Lúpus Eritematoso Sistêmico/complicações , Lúpus Eritematoso Sistêmico/terapia , Guias de Prática Clínica como Assunto , Adolescente , Adulto , França , Humanos , Hospedeiro Imunocomprometido , Controle de Infecções/métodos , Infecções/diagnóstico , Lúpus Eritematoso Sistêmico/diagnóstico , Lúpus Eritematoso Sistêmico/imunologia , Literatura de Revisão como Assunto , Vacinação/normas , Adulto JovemRESUMO
OBJECTIVES: The objective of this article is to describe the outcome (mortality, kidney transplantation) of patients with systemic lupus erythematosus (SLE) on chronic dialysis. METHODS: The overall and cardiovascular (CV) mortality and access to kidney transplantation were studied in all SLE patients incident on chronic dialysis in France between 2002 and 2012 (REIN registry). They were compared to age- and sex-matched patients with diabetic nephropathy and with autosomal dominant polycystic kidney disease (PKD) on chronic dialysis. RESULTS: A total of 368 SLE patients were included in the national REIN registry between 2002 and 2012. Cumulative incidence of death was 16.9% at five years, with no difference between haemodialysis and peritoneal dialysis. Independent risk factors of death were age, past history of cardiovascular disease (CVD) and chronic respiratory insufficiency. At five years, CV and all-cause mortality in SLE patients were lower than in matched diabetic patients, but three-fold higher than in matched PKD patients. Access to the kidney transplant waiting list and to kidney transplantation was higher in SLE patients than in matched diabetic patients, but lower than in matched PKD patients. CONCLUSIONS: SLE patients on chronic dialysis are a population at high risk of death influenced by CV burden and chronic respiratory failure, but not by the method of dialysis. Their outcome, in terms of mortality and access to kidney transplantation, is intermediate between diabetic patients and patients with PKD.
Assuntos
Lúpus Eritematoso Sistêmico/terapia , Diálise Peritoneal/métodos , Diálise Renal/métodos , Adulto , Progressão da Doença , Feminino , França/epidemiologia , Acessibilidade aos Serviços de Saúde , Humanos , Incidência , Transplante de Rim , Lúpus Eritematoso Sistêmico/epidemiologia , Lúpus Eritematoso Sistêmico/mortalidade , Masculino , Pessoa de Meia-Idade , Sistema de Registros , Fatores de Risco , Resultado do TratamentoRESUMO
PURPOSE: To develop French recommendations about screening and management of cardiovascular risk factors in systemic lupus erythematosus (SLE). METHODS: Thirty-nine experts qualified in internal medicine, rheumatology and nephrology have selected recommendations from a list developed based on evidence from the literature. For each recommendation, the level of evidence and the level of agreement among the experts were specified. RESULTS: Experts recommended an annual screening of cardiovascular risk factors in SLE. Statins should be prescribed for primary prevention in SLE patients based on the level of LDL-cholesterol and the number of cardiovascular risk factors, considering SLE as an additional risk factor. For secondary prevention, experts have agreed on an LDL-cholesterol target of <0.7 g/L. Hypertension should be managed according to the 2013 European guidelines, using renin-angiotensin system blockers as first line agents in case of renal involvement. Aspirin can be prescribed in patients with high cardiovascular risk or with antiphospholipid antibodies. CONCLUSION: These recommendations about the screening and management of cardiovascular risk factors in SLE can be expected to improve clinical practice uniformity and, in the longer term, to optimize the management of SLE patients.
Assuntos
Doenças Cardiovasculares/etiologia , Lúpus Eritematoso Sistêmico/complicações , Programas de Rastreamento/métodos , Doenças Cardiovasculares/diagnóstico , Doenças Cardiovasculares/tratamento farmacológico , Medicina Baseada em Evidências , Prova Pericial , Guias como Assunto , Humanos , Fatores de Risco , Prevenção SecundáriaRESUMO
The ANTICIPE study is a cross-sectional, multicenter, French study. The aim of this study was to describe clinical and biological parameters observed in a cohort of 1446 stable renal transplant recipients, according to the stage of chronic kidney disease. Severe infection was defined as an infection necessitating ≥ 7 days of hospital stay. We observed a negative correlation between declining glomerular filtration rate and occurrence of severe infection (P < .0001). In multivariate analysis, severe infection was associated with age, female gender, chronic kidney disease stage (Kidney Disease Outcomes Quality Initiative classification), and number of acute rejection episodes. Our study suggested that renal allograft function is a predictor not only of cardiac death and cardiovascular complications, but also of severe infections.
Assuntos
Doenças Transmissíveis/epidemiologia , Transplante de Rim/efeitos adversos , Rim/fisiopatologia , Adulto , Idoso , Doenças Transmissíveis/diagnóstico , Estudos Transversais , Feminino , França/epidemiologia , Taxa de Filtração Glomerular , Humanos , Tempo de Internação , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Razão de Chances , Prevalência , Fatores de Risco , Índice de Gravidade de Doença , Fatores de Tempo , Resultado do TratamentoRESUMO
The prevalence of the renal involvement is estimated at 40% during the course of systemic lupus erythematosus. In more than half of cases, the histological evaluation leads to the diagnosis of a severe glomerulonephritis (class III or IV A or A/C of the 2003 ISN/RPS classification) which requires a powerful treatment aiming at the remission of the nephritis, at the prevention of relapses, and at the prevention of chronic renal failure and death, with low toxicity. This review focuses on the most important trials of the last three decades that progressively delineated the treatment regimens used for lupus proliferative glomerulonephritis with active lesions. The treatment should consist in an induction regimen followed by a maintenance regimen. Until now, the standard induction associates corticosteroids and intravenous cyclophosphamide, and the most efficient regimen for maintenance with the best tolerance profile is the association of low dose corticosteroids and azathioprine or mycophenolate mofetil. However, the use of cyclophosphamide is limited by its side effects and its cumulated dose should be reduced as much as possible. When cyclophosphamide is not considered for induction, azathioprine or mycophenolate mofetil associated with steroids may constitute an alternative regimen. However, azathioprine seems less effective than cyclophosphamide to prevent relapses and preserve the renal function on a long-term basis. Preliminary data evaluating induction with mycophenolate mofetil are promising, but ongoing trials are needed to determine if induction with mycophenolate mofetil could reach this goal.
Assuntos
Glomerulonefrite/tratamento farmacológico , Glomerulonefrite/etiologia , Lúpus Eritematoso Sistêmico/complicações , Azatioprina/uso terapêutico , Protocolos Clínicos , Ciclofosfamida/uso terapêutico , Humanos , Ácido Micofenólico/análogos & derivados , Guias de Prática Clínica como AssuntoRESUMO
Heat-shock protein 70 (Hsp70) has been reported to block apoptosis by binding apoptosis protease activating factor-1 (Apaf-1), thereby preventing constitution of the apoptosome, the Apaf-1/cytochrome c/caspase-9 activation complex [1,2]. Here we show that overexpression of Hsp70 protects Apaf-1-/- cells against death induced by serum withdrawal, indicating that Apaf-1 is not the only target of the anti-apoptotic action of Hsp70. We investigated the effect of Hsp70 on apoptosis mediated by the caspase-independent death effector apoptosis inducing factor (AIF), which is a mitochondrial intermembrane flavoprotein [3,4]. In a cell-free system, Hsp70 prevented the AIF-induced chromatin condensation of purified nuclei. Hsp70 specifically interacted with AIF, as shown by ligand blots and co-immunoprecipitation. Cells overexpressing Hsp70 were protected against the apoptogenic effects of AIF targeted to the extramitochondrial compartment. In contrast, an anti-sense Hsp70 complementary DNA, which reduced the expression of endogenous Hsp70, increased sensitivity to the lethal effect of AIF. The ATP-binding domain of Hsp70 seemed to be dispensable for inhibiting cell death induced by serum withdrawal, AIF binding and AIF inhibition, although it was required for Apaf-1 binding. Together, our data indicate that Hsp70 can inhibit apoptosis by interfering with target proteins other than Apaf-1, one of which is AIF.
Assuntos
Apoptose/fisiologia , Fibroblastos/citologia , Fibroblastos/fisiologia , Flavoproteínas/metabolismo , Proteínas de Choque Térmico HSP70/metabolismo , Proteínas de Membrana/metabolismo , Proteínas/metabolismo , Animais , Fator de Indução de Apoptose , Fator Apoptótico 1 Ativador de Proteases , Núcleo Celular/ultraestrutura , Sobrevivência Celular , Células Cultivadas , Cromatina/fisiologia , Cromatina/ultraestrutura , Meios de Cultura Livres de Soro , Flavoproteínas/genética , Proteínas de Membrana/genética , Camundongos , Proteínas/antagonistas & inibidores , Proteínas/genética , Proteínas Recombinantes/metabolismo , TransfecçãoRESUMO
Programmed cell death is a fundamental requirement for embryogenesis, organ metamorphosis and tissue homeostasis. In mammals, release of mitochondrial cytochrome c leads to the cytosolic assembly of the apoptosome-a caspase activation complex involving Apaf1 and caspase-9 that induces hallmarks of apoptosis. There are, however, mitochondrially regulated cell death pathways that are independent of Apaf1/caspase-9. We have previously cloned a molecule associated with programmed cell death called apoptosis-inducing factor (AIF). Like cytochrome c, AIF is localized to mitochondria and released in response to death stimuli. Here we show that genetic inactivation of AIF renders embryonic stem cells resistant to cell death after serum deprivation. Moreover, AIF is essential for programmed cell death during cavitation of embryoid bodies-the very first wave of cell death indispensable for mouse morphogenesis. AIF-dependent cell death displays structural features of apoptosis, and can be genetically uncoupled from Apaf1 and caspase-9 expression. Our data provide genetic evidence for a caspase-independent pathway of programmed cell death that controls early morphogenesis.
Assuntos
Apoptose/fisiologia , Flavoproteínas/fisiologia , Proteínas de Membrana/fisiologia , Mitocôndrias/fisiologia , Animais , Fator de Indução de Apoptose , Fator Apoptótico 1 Ativador de Proteases , Caspase 9 , Caspases/metabolismo , Diferenciação Celular , Quimera , Embrião de Mamíferos/citologia , Desenvolvimento Embrionário e Fetal/fisiologia , Feminino , Flavoproteínas/genética , Marcação de Genes , Masculino , Proteínas de Membrana/genética , Camundongos , Camundongos Endogâmicos C57BL , Morfogênese , Proteínas/fisiologia , Recombinação Genética , Células-TroncoRESUMO
The complete AIF cDNA comprising the amino-terminal mitochondrial localization sequence (MLS) and the oxidoreductase domain has been fused in its carboxyl terminus to enhanced green fluorescent protein (GFP), thereby engineering an AIF-GFP fusion protein that is selectively targeted to the mitochondrial intermembrane space. Upon induction of apoptosis, the AIF-GFP protein translocates together with cytochrome c (Cyt-c) to the extramitochondrial compartment. Microinjection of recombinant AIF leads to the release of AIF-GFP and Cyt-c-GFP, indicating that ectopic AIF can favor permeabilization of the outer mitochondrial membrane. These mitochondrial effects of AIF are caspase independent, whereas the Cyt-c-microinjection induced translocation of AIF-GFP and Cyt-c-GFP is suppressed by the pan-caspase inhibitor Z-VAD.fmk. Upon prolonged culture, transfection-enforced overexpression of AIF results in spontaneous translocation of AIF-GFP from mitochondria, nuclear chromatin condensation, and cell death. These effects are caspase independent and do not rely on the oxidoreductase function of AIF. Spontaneous AIF-GFP translocation and subsequent nuclear apoptosis can be retarded by overexpression of a Bcl-2 protein selectively targeted to mitochondria, but not by a Bcl-2 protein targeted to the endoplasmic reticulum. Overexpression of a mutant AIF protein in which the MLS has been deleted (AIF Delta 1-100) results in the primary cytosolic accumulation of AIF. AIF Delta 1-100-induced cell death is suppressed by neither Z-VAD.fmk or by Bcl-2. Thus, extramitochondrially targeted AIF is a dominant cell death inducer.
Assuntos
Apoptose/fisiologia , Flavoproteínas/metabolismo , Proteínas de Membrana/metabolismo , Mitocôndrias/metabolismo , Sinais Direcionadores de Proteínas/genética , Transporte Proteico/fisiologia , Transporte Ativo do Núcleo Celular , Sequência de Aminoácidos , Animais , Fator de Indução de Apoptose , Células COS , Clonagem Molecular , Cricetinae , Grupo dos Citocromos c/genética , Grupo dos Citocromos c/metabolismo , Flavoproteínas/genética , Corantes Fluorescentes/metabolismo , Genes Reporter/genética , Proteínas de Fluorescência Verde , Humanos , Proteínas Luminescentes/metabolismo , Proteínas de Membrana/genética , Microinjeções , Microscopia Confocal , Dados de Sequência Molecular , Proteínas Proto-Oncogênicas c-bcl-2/genética , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Ratos , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Alinhamento de Sequência , Fatores de Tempo , TransfecçãoRESUMO
Apaf-1(-/-) or caspase-3(-/-) cells treated with a variety of apoptosis inducers manifest apoptosis-associated alterations including the translocation of apoptosis-inducing factor (AIF) from mitochondria to nuclei, large scale DNA fragmentation, and initial chromatin condensation (stage I). However, when compared with normal control cells, Apaf-1(-/-) or caspase-3(-/-) cells fail to exhibit oligonucleosomal chromatin digestion and a more advanced pattern of chromatin condensation (stage II). Microinjection of such cells with recombinant AIF only causes peripheral chromatin condensation (stage I), whereas microinjection with activated caspase-3 or its downstream target caspase-activated DNAse (CAD) causes a more pronounced type of chromatin condensation (stage II). Similarly, when added to purified HeLa nuclei, AIF causes stage I chromatin condensation and large-scale DNA fragmentation, whereas CAD induces stage II chromatin condensation and oligonucleosomal DNA degradation. Furthermore, in a cell-free system, concomitant neutralization of AIF and CAD is required to suppress the nuclear DNA loss caused by cytoplasmic extracts from apoptotic wild-type cells. In contrast, AIF depletion alone suffices to suppress the nuclear DNA loss contained in extracts from apoptotic Apaf-1(-/-) or caspase-3(-/-) cells. As a result, at least two redundant parallel pathways may lead to chromatin processing during apoptosis. One of these pathways involves Apaf-1 and caspases, as well as CAD, and leads to oligonucleosomal DNA fragmentation and advanced chromatin condensation. The other pathway, which is caspase-independent, involves AIF and leads to large-scale DNA fragmentation and peripheral chromatin condensation.
Assuntos
Apoptose/fisiologia , Caspases/metabolismo , Núcleo Celular/metabolismo , Flavoproteínas/metabolismo , Proteínas de Membrana/metabolismo , Mitocôndrias/metabolismo , Proteínas/metabolismo , Animais , Antineoplásicos/farmacologia , Fator de Indução de Apoptose , Fator Apoptótico 1 Ativador de Proteases , Arsenitos/farmacologia , Caspase 3 , Caspases/genética , Células Cultivadas , Cisplatino/farmacologia , Grupo dos Citocromos c/genética , Grupo dos Citocromos c/metabolismo , Fragmentação do DNA , Desoxirribonucleases/genética , Desoxirribonucleases/metabolismo , Etoposídeo/farmacologia , Fibroblastos/metabolismo , Fibroblastos/ultraestrutura , Flavoproteínas/genética , Corantes Fluorescentes/metabolismo , Células HeLa , Humanos , Proteínas de Membrana/genética , Camundongos , Camundongos Knockout , Microinjeções , Proteínas/genética , Proteínas Recombinantes/metabolismoRESUMO
Apoptosis-inducing factor (AIF) is encoded by one single gene located on the X chromosome. AIF is ubiquitously expressed, both in normal tissues and in a variety of cancer cell lines. The AIF precursor is synthesized in the cytosol and is imported into mitochondria. The mature AIF protein, a flavoprotein (prosthetic group: flavine adenine dinucleotide) with significant homology to plant ascorbate reductases and bacterial NADH oxidases, is normally confined to the mitochondrial intermembrane space. In a variety of different apoptosis-inducing conditions, AIF translocates through the outer mitochondrial membrane to the cytosol and to the nucleus. Ectopic (extra-mitochondrial) AIF induces nuclear chromatin condensation, as well as large scale ( approximately 50 kb) DNA fragmentation. Thus, similar to cytochrome c, AIF is a phylogenetically old, bifunctional protein with an electron acceptor/donor (oxidoreductase) function and a second apoptogenic function. In contrast to cytochrome c, however, AIF acts in a caspase-independent fashion. The molecular mechanisms via which AIF induces apoptosis are discussed.
Assuntos
Apoptose/fisiologia , Flavoproteínas/metabolismo , Proteínas de Membrana/metabolismo , Mitocôndrias/metabolismo , Oxirredutases/metabolismo , Animais , Apoptose/efeitos dos fármacos , Fator de Indução de Apoptose , DNA Complementar/genética , Flavoproteínas/genética , Flavoproteínas/farmacologia , Expressão Gênica , Humanos , Proteínas de Membrana/genética , Proteínas de Membrana/farmacologia , Oxirredutases/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Distribuição Tecidual , Cromossomo X/genéticaRESUMO
Caspase activation may occur in a direct fashion as a result of CD95 death receptor crosslinking (exogenous pathway) or may be triggered indirectly, via a Bcl-2 inhibitable mitochondrial permeabilization event (endogenous pathway). Thymocyte apoptosis is generally accompanied by proteasome activation. If death is induced by DNA damage, inactivation of p53, overexpression of a Bcl-2 transgene, inhibition of protein synthesis, and antioxidants (N-acetylcyteine, catalase) prevent proteasome activation. Glucocorticoid-induced proteasome activation follows a similar pattern of inhibition except for p53. Caspase inhibition fails to affect proteasome activation induced by topoisomerase inhibition or glucocorticoid receptor ligation. In contrast, caspase activation (but not p53 knockout or Bcl-2 overexpression) does interfere with proteasome activation induced by CD95. Specific inhibition of proteasomes with lactacystin or MG123 blocks caspase activation at a pre-mitochondrial level if thymocyte apoptosis is induced by DNA damage or glucocorticoids. In strict contrast, proteasome inhibition has no inhibitory effect on the mitochondrial and nuclear phases of apoptosis induced via CD95. Thus, proteasome activation is a critical event of thymocyte apoptosis stimulated via the endogenous pathway yet dispensable for CD95-triggered death.
Assuntos
Apoptose/fisiologia , Cisteína Endopeptidases/metabolismo , Complexos Multienzimáticos/metabolismo , Linfócitos T/fisiologia , Receptor fas/fisiologia , Acetilcisteína/farmacologia , Clorometilcetonas de Aminoácidos/farmacologia , Animais , Antioxidantes/farmacologia , Apoptose/efeitos dos fármacos , Inibidores de Caspase , Caspases/metabolismo , Catalase/farmacologia , Células Cultivadas , Cisteína Endopeptidases/efeitos dos fármacos , Dactinomicina/farmacologia , Dexametasona/farmacologia , Ativação Enzimática , Etoposídeo/farmacologia , Feminino , Camundongos , Camundongos Endogâmicos BALB C , Mitocôndrias/metabolismo , Complexos Multienzimáticos/efeitos dos fármacos , Complexo de Endopeptidases do Proteassoma , Linfócitos T/citologia , Linfócitos T/efeitos dos fármacosRESUMO
Apoptosis inducing factor (AIF) is a novel apoptotic effector protein that induces chromatin condensation and large-scale ( approximately 50 kbp) DNA fragmentation when added to purified nuclei in vitro. Confocal and electron microscopy reveal that, in normal cells, AIF is strictly confined to mitochondria and thus colocalizes with heat shock protein 60 (hsp60). On induction of apoptosis by staurosporin, c-Myc, etoposide, or ceramide, AIF (but not hsp60) translocates to the nucleus. This suggests that only the outer mitochondrial membrane (which retains AIF in the intermembrane space) but not the inner membrane (which retains hsp60 in the matrix) becomes protein permeable. The mitochondrio-nuclear redistribution of AIF is prevented by a Bcl-2 protein specifically targeted to mitochondrial membranes. The pan-caspase inhibitor Z-VAD. fmk does not prevent the staurosporin-induced translocation of AIF, although it does inhibit oligonucleosomal DNA fragmentation and arrests chromatin condensation at an early stage. ATP depletion is sufficient to cause AIF translocation to the nucleus, and this phenomenon is accelerated by the apoptosis inducer staurosporin. However, in conditions in which both glycolytic and respiratory ATP generation is inhibited, cells fail to manifest any sign of chromatin condensation and advanced DNA fragmentation, thus manifesting a 'necrotic' phenotype. Both in the presence of Z-VAD. fmk and in conditions of ATP depletion, AIF translocation correlates with the appearance of large-scale DNA fragmentation. Altogether, these data are compatible with the hypothesis that AIF is a caspase-independent mitochondrial death effector responsible for partial chromatinolysis.
Assuntos
Apoptose/fisiologia , Flavoproteínas/metabolismo , Proteínas de Membrana/metabolismo , Necrose , Trifosfato de Adenosina/metabolismo , Animais , Apoptose/efeitos dos fármacos , Fator de Indução de Apoptose , Transporte Biológico Ativo , Caspases/metabolismo , Linhagem Celular , Núcleo Celular/metabolismo , Cromatina/metabolismo , Grupo dos Citocromos c/metabolismo , Dano ao DNA , Humanos , Microscopia Confocal , Microscopia Eletrônica , Mitocôndrias/metabolismo , Modelos Biológicos , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Proteínas Proto-Oncogênicas c-myc/metabolismo , Ratos , Estaurosporina/farmacologiaRESUMO
Mitochondrial membrane permeabilization is a rate-limiting step of cell death. This process is, at least in part, mediated by opening of the permeability transition pore complex (PTPC) Several soluble proteins from the mitochondrial intermembrane space and matrix are involved in the activation of catabolic hydrolases including caspases and nucleases. We therefore investigated the composition of a mixture of proteins released from purified mitochondria upon PTPC opening. This mixture was subjected to a novel proteomics/mass spectrometric approach designed to identify a maximum of peptides. Peptides from a total of 79 known proteins or genes were identified. In addition, 21 matches with expressed sequence tags (EST) were obtained. Among the known proteins, several may have indirect or direct pro-apoptotic properties. Thus endozepine, a ligand of the peripheral benzodiazepin receptor (whose occupation may facilitate mitochondrial membrane permeabilization), was found among the released proteins. Several proteins involved in protein import were also released, namely the so-called X-linked deafness dystonia protein (DDP) and the glucose regulated protein 75 (grb75), meaning that protein import may become irreversibly disrupted in mitochondria of apoptotic cells. In addition, a number of catabolic enzymes are detected: arginase 1 (which degrades arginine), sulfite oxidase (which degrades sulfur amino acids), and epoxide hydrolase. Although the functional impact of each of these proteins on apoptosis remains elusive, the present data bank of mitochondrial proteins released upon PTPC opening should help further elucidation of the death process.
Assuntos
Apoptose , Permeabilidade da Membrana Celular , Mitocôndrias Hepáticas/metabolismo , Mitocôndrias Hepáticas/patologia , Proteínas/metabolismo , Sequência de Aminoácidos , Animais , Espectrometria de Massas , Camundongos , Dados de Sequência Molecular , Fragmentos de Peptídeos , Proteínas/químicaRESUMO
Viral protein R (Vpr) encoded by HIV-1 is a facultative inducer of apoptosis. When added to intact cells or purified mitochondria, micromolar and submicromolar doses of synthetic Vpr cause a rapid dissipation of the mitochondrial transmembrane potential (DeltaPsi(m)), as well as the mitochondrial release of apoptogenic proteins such as cytochrome c or apoptosis inducing factor. The same structural motifs relevant for cell killing are responsible for the mitochondriotoxic effects of Vpr. Both mitochondrial and cytotoxic Vpr effects are prevented by Bcl-2, an inhibitor of the permeability transition pore complex (PTPC). Coincubation of purified organelles revealed that nuclear apoptosis is only induced by Vpr when mitochondria are present yet can be abolished by PTPC inhibitors. Vpr favors the permeabilization of artificial membranes containing the purified PTPC or defined PTPC components such as the adenine nucleotide translocator (ANT) combined with Bax. Again, this effect is prevented by addition of recombinant Bcl-2. The Vpr COOH terminus binds purified ANT, as well as a molecular complex containing ANT and the voltage-dependent anion channel (VDAC), another PTPC component. Yeast strains lacking ANT or VDAC are less susceptible to Vpr-induced killing than control cells yet recover Vpr sensitivity when retransfected with yeast ANT or human VDAC. Hence, Vpr induces apoptosis via a direct effect on the mitochondrial PTPC.