RESUMO
Mitochondrial topoisomerase IB (TOP1MT) is a nuclear-encoded topoisomerase, exclusively localized to mitochondria, which resolves topological stress generated during mtDNA replication and transcription. Here, we report that TOP1MT is overexpressed in cancer tissues and demonstrate that TOP1MT deficiency attenuates tumor growth in human and mouse models of colon and liver cancer. Due to their mitochondrial dysfunction, TOP1MT-KO cells become addicted to glycolysis, which limits synthetic building blocks and energy supply required for the proliferation of cancer cells in a nutrient-deprived tumor microenvironment. Mechanistically, we show that TOP1MT associates with mitoribosomal subunits, ensuring optimal mitochondrial translation and assembly of oxidative phosphorylation complexes that are critical for sustaining tumor growth. The TOP1MT genomic signature profile, based on Top1mt-KO liver cancers, is correlated with enhanced survival of hepatocellular carcinoma patients. Our results highlight the importance of TOP1MT for tumor development, providing a potential rationale to develop TOP1MT-targeted drugs as anticancer therapies.
Assuntos
Carcinogênese/patologia , Carcinoma Hepatocelular/patologia , DNA Topoisomerases Tipo I/metabolismo , Neoplasias Hepáticas Experimentais/patologia , Neoplasias Hepáticas/patologia , Mitocôndrias/metabolismo , Biossíntese de Proteínas , Animais , Carcinógenos/toxicidade , Carcinoma Hepatocelular/genética , Carcinoma Hepatocelular/metabolismo , Carcinoma Hepatocelular/mortalidade , Núcleo Celular/metabolismo , Proliferação de Células , DNA Topoisomerases Tipo I/genética , DNA Mitocondrial/genética , DNA Mitocondrial/isolamento & purificação , Conjuntos de Dados como Assunto , Metabolismo Energético , Feminino , Fibroblastos , Perfilação da Expressão Gênica , Regulação Neoplásica da Expressão Gênica , Glicólise , Células HCT116 , Humanos , Fígado/citologia , Fígado/metabolismo , Fígado/patologia , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/metabolismo , Neoplasias Hepáticas/mortalidade , Neoplasias Hepáticas Experimentais/induzido quimicamente , Neoplasias Hepáticas Experimentais/genética , Neoplasias Hepáticas Experimentais/metabolismo , Masculino , Camundongos , Camundongos Knockout , Camundongos Nus , Mitocôndrias/patologia , Prognóstico , Análise de Sobrevida , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Mitochondrial ribosomes and translation factors co-purify with mitochondrial nucleoids of human cells, based on affinity protein purification of tagged mitochondrial DNA binding proteins. Among the most frequently identified proteins were ATAD3 and prohibitin, which have been identified previously as nucleoid components, using a variety of methods. Both proteins are demonstrated to be required for mitochondrial protein synthesis in human cultured cells, and the major binding partner of ATAD3 is the mitochondrial ribosome. Altered ATAD3 expression also perturbs mtDNA maintenance and replication. These findings suggest an intimate association between nucleoids and the machinery of protein synthesis in mitochondria. ATAD3 and prohibitin are tightly associated with the mitochondrial membranes and so we propose that they support nucleic acid complexes at the inner membrane of the mitochondrion.
Assuntos
Mitocôndrias/genética , Proteínas Mitocondriais/biossíntese , Nucleoproteínas/fisiologia , Biossíntese de Proteínas , ATPases Associadas a Diversas Atividades Celulares , Adenosina Trifosfatases/metabolismo , Proteínas de Ciclo Celular/fisiologia , Linhagem Celular Tumoral , DNA Mitocondrial/metabolismo , Células HEK293 , Humanos , Proteínas de Membrana/metabolismo , Proteínas Mitocondriais/metabolismo , Proteínas Mitocondriais/fisiologia , Proteínas Nucleares/fisiologia , Proibitinas , RNA/análise , RNA/isolamento & purificação , RNA Mensageiro/análise , RNA Mitocondrial , Proteínas Repressoras/fisiologia , Ribossomos/metabolismoRESUMO
Mitochondrial disorders are a group of diseases traditionally ascribed to defects of the respiratory chain, which is the only metabolic pathway in the cell that is under the control of the two separate genetic systems, the mitochondrial genome (mtDNA) and the nuclear genome (nDNA). Therefore the genetic classification of the primary mitochondrial diseases distinguishes disorders due to mutations in mtDNA, which are sporadic or maternal inherited, from disorders due to mutations in nDNA, which are governed by the stricter rules of mendelian genetics. Pathological alterations of mtDNA fall into two main categories: primary mutations of mitochondrial DNA (point mutations and rearrangements) and mtDNA perturbation, due to mutations in nuclear genes whose products are involved in mtDNA maintenance or replication. This article will focus on the primary mitochondrial DNA mutations and mtDNA depletion syndromes related to neonatal-infant human pathology.
Assuntos
DNA Mitocondrial/genética , Mitocôndrias/genética , Doenças Mitocondriais/genética , Mutação , DNA Mitocondrial/metabolismo , Transporte de Elétrons/genética , Humanos , Recém-Nascido , Mitocôndrias/metabolismo , Doenças Mitocondriais/metabolismoRESUMO
OBJECTIVES: These EFNS guidelines on the molecular diagnosis of motoneuron disorders, neuropathies and myopathies are designed to summarize the possibilities and limitations of molecular genetic techniques and to provide diagnostic criteria for deciding when a molecular diagnostic work-up is indicated. SEARCH STRATEGY: To collect data about planning, conditions and performance of molecular diagnosis of these disorders, a literature search in various electronic databases was carried out and original papers, meta-analyses, review papers and guideline recommendations reviewed. RESULTS: The best level of evidence for genetic testing recommendation (B) can be found for the disorders with specific presentations, including familial amyotrophic lateral sclerosis, spinal and bulbar muscular atrophy, Charcot-Marie-Tooth 1A, myotonic dystrophy and Duchenne muscular dystrophy. For a number of less common disorders, a precise description of the phenotype, including the use of immunologic methods in the case of myopathies, is considered as good clinical practice to guide molecular genetic testing. CONCLUSION: These guidelines are provisional and the future availability of molecular-genetic epidemiological data about the neurogenetic disorders under discussion in this article will allow improved recommendation with an increased level of evidence.
Assuntos
Técnicas de Diagnóstico Molecular , Doença dos Neurônios Motores/diagnóstico , Doenças Musculares/diagnóstico , Doenças do Sistema Nervoso Periférico/diagnóstico , Humanos , Doença dos Neurônios Motores/genética , Doenças Musculares/genética , Doenças do Sistema Nervoso Periférico/genéticaRESUMO
OBJECTIVES: These EFNS guidelines on the molecular diagnosis of channelopathies, including epilepsy and migraine, as well as stroke, and dementia are designed to summarize the possibilities and limitations of molecular genetic techniques and to provide diagnostic criteria for deciding when a molecular diagnostic work-up is indicated. SEARCH STRATEGY: To collect data about planning, conditions, and performance of molecular diagnosis of these disorders, a literature search in various electronic databases was carried out and original papers, meta-analyses, review papers, and guideline recommendations were reviewed. RESULTS: The best level of evidence for genetic testing recommendation (B) can be found for a small number of syndromes, cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy, severe myoclonic epilepsy of infancy, familial recurrent hemorrhages, familial Alzheimer's disease, and frontotemporal lobar degeneration. Good practice points can be formulated for a number of other disorders. CONCLUSION: These guidelines are provisional, and the future availability of molecular genetic epidemiological data about the neurogenetic disorders under discussion in our article will allow improved recommendation with an increased level of evidence.
Assuntos
Canalopatias/diagnóstico , Demência/diagnóstico , Epilepsia/diagnóstico , Transtornos de Enxaqueca/diagnóstico , Biologia Molecular/normas , Técnicas de Diagnóstico Molecular/métodos , Técnicas de Diagnóstico Molecular/normas , Acidente Vascular Cerebral/diagnóstico , Canalopatias/epidemiologia , Canalopatias/genética , Demência/epidemiologia , Demência/genética , Epilepsia/epidemiologia , Epilepsia/genética , Europa (Continente)/epidemiologia , Medicina Baseada em Evidências , Humanos , Recém-Nascido , Transtornos de Enxaqueca/epidemiologia , Transtornos de Enxaqueca/genética , Biologia Molecular/métodos , Biologia Molecular/tendências , Técnicas de Diagnóstico Molecular/tendências , Sociedades Médicas/normas , Sociedades Médicas/tendências , Acidente Vascular Cerebral/epidemiologia , Acidente Vascular Cerebral/genéticaRESUMO
BACKGROUND AND PURPOSE: These EFNS guidelines on the molecular diagnosis of neurogenetic disorders are designed to provide practical help for the general neurologist to make appropriate use of molecular genetics in diagnosing neurogenetic disorders. METHODS: Literature searches were performed before expert members of the task force wrote proposals, which were discussed in detail until final consensus had been reached among all task force members. RESULTS AND CONCLUSION: This paper provides updated guidelines for molecular diagnosis of two particularly complex groups of disorders, the ataxias and spastic paraplegias. Possibilities and limitations of molecular genetic diagnosis of these disorders are evaluated and recommendations are provided.
Assuntos
Ataxia/diagnóstico , Ataxia/genética , Paraplegia Espástica Hereditária/diagnóstico , Paraplegia Espástica Hereditária/genética , Ataxia/metabolismo , Humanos , Paraplegia/diagnóstico , Paraplegia/genética , Paraplegia/metabolismo , Paraplegia Espástica Hereditária/metabolismoRESUMO
OBJECTIVES: These European Federation of Neurological Sciences (EFNS) guidelines are designed to provide practical help for the general neurologist to make appropriate use of molecular genetics for diagnosing mitochondrial disorders (MIDs), which gain increasing attention and are more frequently diagnosed due to improved diagnostic tools. BACKGROUND: Since the publication of the first EFNS guidelines on the molecular diagnosis of inherited neurological diseases in 2001, rapid progress has been made in this field, necessitating the creation of an updated version. SEARCH STRATEGY: To collect data about the molecular diagnosis of MIDs search for literature in various electronic databases, such as Cochrane library, MEDLINE, OMIM, GENETEST or Embase, were carried out and original papers, meta-analyses, review papers, and guideline recommendations were reviewed. RESULTS: The guidelines summarise the possibilities and limitations of molecular genetic diagnosis of MIDs and provide practical recommendations and diagnostic criteria in accordance with the EFNS Scientific Committee to guide the molecular diagnostic work-up of MIDs. RECOMMENDATIONS: The proposed guidelines suggest an approach to the molecular diagnosis of MIDs in a manner accessible to general neurologists.
Assuntos
Doenças Mitocondriais/diagnóstico , Doenças Mitocondriais/genética , Biologia Molecular/métodos , HumanosRESUMO
These tables list both published and a number of unpublished mutations in genes associated with early onset defects in mitochondrial DNA (mtDNA) maintenance including C10orf2, SUCLG1, SUCLA2, TYMP, RRM2B, MPV17, DGUOK and TK2. The list should not be taken as evidence that any particular mutation is pathogenic. We have included genes known to cause mtDNA depletion, excluding POLG1, because of the existing database (http://tools.niehs.nih.gov/polg/). We have also excluded mutations in C10orf2 associated with dominant adult onset disorders.
Assuntos
DNA Mitocondrial/genética , Genes Mitocondriais/genética , Doenças Mitocondriais/genética , Mutação/genética , Humanos , SíndromeRESUMO
BACKGROUND AND PURPOSE: These EFNS guidelines on the molecular diagnosis of neurogenetic disorders are designed to provide practical help for the general neurologist to make appropriate use of molecular genetics in diagnosing neurogenetic disorders. Since the publication of the first two EFNS-guideline papers on the molecular diagnosis of neurological diseases in 2001, rapid progress has been made in this field, necessitating an updated series of guidelines. METHODS: Literature searches were performed before expert members of the task force wrote proposals, which were discussed in detail until final consensus had been reached among all task force members. RESULTS AND CONCLUSION: This paper provides updated guidelines for molecular diagnosis of Huntington's disease, Parkinson's disease and dystonias as well as a general introduction to the topic. Possibilities and limitations of molecular genetic diagnosis of these disorders are evaluated and recommendations are provided.
Assuntos
Distonia/diagnóstico , Guias como Assunto/normas , Doença de Huntington/diagnóstico , Técnicas de Diagnóstico Molecular/métodos , Doença de Parkinson/diagnóstico , Bases de Dados Bibliográficas/estatística & dados numéricos , Distonia/genética , Aconselhamento Genético/métodos , Humanos , Doença de Huntington/genética , Doença de Parkinson/genéticaRESUMO
In the course of evolution, mitochondria lost their independence, and mitochondrial DNA (mtDNA) became the 'slave' of nuclear DNA, depending on numerous nucleus-encoded factors for its integrity, replication and expression. Mutations in any of these factors may alter the cross-talk between the two genomes and cause Mendelian disorders characterized by qualitative (multiple deletions) or quantitative (depletion) alterations of mtDNA, or by defective translation of mtDNA-encoded respiratory chain components.
Assuntos
DNA Mitocondrial/genética , Deleção de Genes , Doenças Mitocondriais/genética , Animais , Modelos Animais de Doenças , Humanos , Camundongos , Doenças Mitocondriais/classificação , Mutação/genética , Fosforilação OxidativaRESUMO
Mitochondrial DNA depletion syndromes (MDSs) form a group of autosomal recessive disorders characterized by profoundly decreased mitochondrial DNA copy numbers in affected tissues. Three main clinical presentations are known: myopathic, encephalomyopathic and hepatocerebral. The first is associated with mutations in thymidine kinase 2 (TK2) and p53-induced ribonucleotide reductase B subunit (RRM2B); the second with mutations in succinate synthase A (SUCLA2) and B (SUCLG1); the third with mutations in Twinkle (PEO1), pol-gammaA (POLG1), deoxyguanosine kinase (DGUOK) and MPV17 (MPV17). In this work, we review the MDS-associated phenotypes and present our own experience of 32 MDS patients, with the aim of defining the mutation frequency of the known genes, the clinical spectrum of the diseases, and the genotype-phenotype correlations. Five of our patients carried previously unreported mutations in one of the eight MDS genes.
Assuntos
DNA Mitocondrial/genética , Doenças Mitocondriais/genética , Doenças Mitocondriais/patologia , Acidose Láctica/etiologia , Idade de Início , Encéfalo/patologia , Criança , Pré-Escolar , Estudos de Coortes , Eletroencefalografia , Eletromiografia , Feminino , Humanos , Lactente , Recém-Nascido , Fígado/patologia , Imageamento por Ressonância Magnética , Masculino , Encefalomiopatias Mitocondriais/genética , Encefalomiopatias Mitocondriais/patologia , Miopatias Mitocondriais/genética , Miopatias Mitocondriais/patologia , Músculo Esquelético/patologia , Mutação/fisiologia , Timidina Quinase/genéticaRESUMO
Catheter-induced iatrogenic pseudoaneurysm is a complication on the rise as compared to the past. This is due to the increasingly frequent use of percutaneous endovascular intervention in the diagnosis and treatment of several diseases. We present a case which underlines the diagnostic and therapeutic role of color Doppler ultrasound (US) in this pathology.
RESUMO
Endovascular treatment of abdominal aortic aneurysm (AAA) involves placement of an endoluminal graft inside the aneurysmal sac in order to exclude it from blood circulation and thereby prevent the risk of aneurysmal sac rupture. A possible complication is endoleak, i.e. persistent blood flow outside the lumen of the endograft into the aneurysmal sac. The protocol for treatment monitoring includes abdominal computed tomography (CT) and color Doppler ultrasound (US). The aim of this case report is to present our experience in two cases of endoleak in which diagnosis and treatment were carried out using color Doppler US.
RESUMO
Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is an autosomal recessive disorder caused by mutations in the gene encoding thymidine phosphorylase (TP). The disease is characterized clinically by impaired eye movements, gastrointestinal dysmotility, cachexia, peripheral neuropathy, myopathy, and leukoencephalopathy. Molecular genetic studies of MNGIE patients' tissues have revealed multiple deletions, depletion, and site-specific point mutations of mitochondrial DNA. TP is a cytosolic enzyme required for nucleoside homeostasis. In MNGIE, TP activity is severely reduced and consequently levels of thymidine and deoxyuridine in plasma are dramatically elevated. We have hypothesized that the increased levels of intracellular thymidine and deoxyuridine cause imbalances of mitochondrial nucleotide pools that, in turn, lead to the mtDNA abnormalities. MNGIE was the first molecularly characterized genetic disorder caused by abnormal mitochondrial nucleoside/nucleotide metabolism. Future studies are likely to reveal further insight into this expanding group of diseases.
Assuntos
Encefalopatias/genética , Doenças Mitocondriais/genética , Doenças Musculares/genética , Timidina Fosforilase/deficiência , Timidina Fosforilase/genética , Southern Blotting , Cromatografia Líquida de Alta Pressão , Genes Recessivos , Ligação Genética , Heterozigoto , Humanos , Doenças Mitocondriais/enzimologia , Modelos Biológicos , Mutação , Mutação Puntual , Espectrofotometria , Timidina/metabolismoRESUMO
Scombroid poisoning is a form of ichthyosarcotoxism caused by eating spoiled fish, mainly of the scombroid family. Inappropriate storage of these fish can lead to the decarboxylation of histidine in the flesh to histamine by enterobacteria. The symptoms of histamine poisoning mimic those of an IgE-mediated food allergy, as well as flushing, headache, diarrhea and palpitations. However, in some cases, the scombroid poisoning can be characterized by very serious symptoms, as well as cardiovascular compromission. We describe two cases of scombroid poisoning with severe hypotension requiring continuous intravenous dopamine with resolution of symptoms only several hours later.
Assuntos
Doenças Cardiovasculares/etiologia , Conservação de Alimentos , Toxinas Marinhas/intoxicação , Adulto , Feminino , Humanos , Masculino , Índice de Gravidade de Doença , Síndrome , Fatores de TempoRESUMO
Two brothers with myopathic coenzyme Q10 (CoQ10) deficiency responded dramatically to CoQ10 supplementation. Muscle biopsies before therapy showed ragged-red fibers, lipid storage, and complex I + III and II + III deficiency. Approximately 30% of myofibers had multiple features of apoptosis. After 8 months of treatment, excessive lipid storage resolved, CoQ10 level normalized, mitochondrial enzymes increased, and proportion of fibers with TUNEL-positive nuclei decreased to 10%. The authors conclude that muscle CoQ10 deficiency can be corrected by supplementation of CoQ10, which appears to stimulate mitochondrial proliferation and to prevent apoptosis.
Assuntos
Músculos/patologia , Doenças Musculares/tratamento farmacológico , Doenças Musculares/patologia , Ubiquinona/análogos & derivados , Ubiquinona/deficiência , Ubiquinona/uso terapêutico , Adolescente , Criança , Pré-Escolar , Coenzimas , Humanos , Imuno-Histoquímica , Masculino , Microscopia Eletrônica , Músculos/ultraestrutura , FenótipoAssuntos
Trifosfato de Adenosina/metabolismo , Mitocôndrias/metabolismo , Adenosina Trifosfatases/genética , Adenosina Trifosfatases/metabolismo , Animais , Bioensaio/métodos , Células Cultivadas , DNA Mitocondrial/genética , DNA Mitocondrial/metabolismo , Digitonina/farmacologia , Fibroblastos/efeitos dos fármacos , Fibroblastos/metabolismo , Luciferina de Vaga-Lumes/metabolismo , Humanos , Indicadores e Reagentes/farmacologia , Doença de Leigh/metabolismo , Luciferases/metabolismo , Medições Luminescentes , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/enzimologia , Doenças Mitocondriais/metabolismoRESUMO
Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is a unique autosomal recessive disorder with mitochondrial DNA alterations. The disease is characterized clinically by ptosis, progressive external ophthalmoparesis, gastrointestinal dysmotility, cachexia, peripheral neuropathy, and leukoencephalopathy. Muscle biopsies typically reveal mitochondrial abnormalities including ragged-red fibers and focal cytochrome c oxidase deficiency. Analysis of mitochondrial DNA in skeletal muscle shows partial depletion, multiple deletions, or both. To identify the cause of MNGIE, we mapped the disease locus to chromosome 22q13.32-qter. Within this region, we identified the gene encoding thymidine phosphorylase as the MNGIE gene. We have identified homozygous or compound-heterozygous thymidine phosphorylase gene mutations in 35 MNGIE patients (21 families) from diverse ethnic groups, including: Ashkenazi Jewish, Western European, Jamaican, Hispanic, and Japanese. We confirmed pathogenicity of the mutations by a spectrophotometric assay of thymidine phosphorylase activity with peripheral leukocytes of 15 MNGIE patients. Thymidine phosphorylase enzymatic activity was severely reduced, thus enabling us to conclude that the loss-of-function mutations in thymidine phosphorylase gene cause MNGIE. Thymidine phosphorylase catabolizes thymidine to thymine. In agreement with this notion, we noted that plasma thymidine level is increased more than 20-fold in MNGIE patients compared to controls. Therefore, we have hypothesized that increased thymidine causes mitochondrial nucleotide pool imbalance which, in turn, leads to motochondrial DNA alterations, via a mitochondria-specific thymidine salvage pathway. The identification of the MNGIE gene has allowed us to classify MNGIE as a disease of nucleoside dysmetabolism. We may be entering a new era of research on mitochondrial nucleoside metabolism.
Assuntos
Cromossomos Humanos Par 22/genética , DNA Mitocondrial/genética , Encefalomiopatias Mitocondriais/genética , Humanos , Encefalomiopatias Mitocondriais/fisiopatologia , Timidina Fosforilase/deficiência , Timidina Fosforilase/genéticaRESUMO
Ticlopidine is an antiplatelet agent that is used to reduce the occurrence of atherothrombotic arterial events, but it can sometime cause severe haematological side-effects. We describe the case of a 79-year old woman suffering from ischaemic cardiopathy and chronic cerebral vasculopathy treated with ticlopidine, who developed a rare pancytopenia on the 26th day of ticlopidine treatment. The patient was successful treated with intravenous antibiotics and with filgrastim, with complete reversion of the pancytopenia.