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1.
Int J Mol Sci ; 22(4)2021 Feb 18.
Artigo em Inglês | MEDLINE | ID: mdl-33670490

RESUMO

The mitochondrial respiratory chain is the main site of reactive oxygen species (ROS) production in the cell. Although mitochondria possess a powerful antioxidant system, an excess of ROS cannot be completely neutralized and cumulative oxidative damage may lead to decreasing mitochondrial efficiency in energy production, as well as an increasing ROS excess, which is known to cause a critical imbalance in antioxidant/oxidant mechanisms and a "vicious circle" in mitochondrial injury. Due to insufficient energy production, chronic exposure to ROS overproduction consequently leads to the oxidative damage of life-important biomolecules, including nucleic acids, proteins, lipids, and amino acids, among others. Different forms of mitochondrial dysfunction (mitochondriopathies) may affect the brain, heart, peripheral nervous and endocrine systems, eyes, ears, gut, and kidney, among other organs. Consequently, mitochondriopathies have been proposed as an attractive diagnostic target to be investigated in any patient with unexplained progressive multisystem disorder. This review article highlights the pathomechanisms of mitochondriopathies, details advanced analytical tools, and suggests predictive approaches, targeted prevention and personalization of medical services as instrumental for the overall management of mitochondriopathy-related cascading pathologies.


Assuntos
Metabolismo Energético , Mitocôndrias/patologia , Doenças Mitocondriais/patologia , Estresse Oxidativo , Animais , Carcinogênese/patologia , Humanos , Mitocôndrias/metabolismo , Doenças Mitocondriais/diagnóstico , Doenças Mitocondriais/metabolismo , Doenças Neurodegenerativas/diagnóstico , Doenças Neurodegenerativas/metabolismo , Doenças Neurodegenerativas/patologia , Medicina de Precisão , Espécies Reativas de Oxigênio/metabolismo
2.
Medicine (Baltimore) ; 100(10): e25100, 2021 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-33725905

RESUMO

BACKGROUND: Mitochondrial diabetes mellitus (MDM) is characterized by maternal inheritance, progressive neurosensory deafness, insulin secretory disorder, and progressive microvascular complications. Mitochondria are critical organelles that provide energy in the form of adenosine triphosphate (ATP). An impairment of ATP production in pancreatic ß cells is regarded as the main cause of the insulin secretory disorder in patients with MDM, and these patients require insulin replacement therapy early after the diagnosis. The amino acid 5-aminolevulinic acid (5-ALA), a precursor of heme metabolites, is a non-proteinogenic δ amino acid synthesized in mitochondria. An addition of ferrous iron to 5-ALA enhances heme biosynthesis and increases ATP production through an upregulation of the respiratory complex. Several studies have reported that the administration of 5-ALA and ferrous iron to existing treatment improved the glycemic control in both patients with prediabetes and those with type 2 diabetes mellitus. The additional administration of 5-ALA and ferrous iron to MDM patients on insulin therapy may improve their insulin secretory capacity and glycemic control by improving their mitochondrial function. The findings of this study are expected to provide new treatment options for MDM and improve the patients' glycemic control and prognosis. METHODS/DESIGN: This study is a single-arm, open-label pilot intervention study using clinical endpoints to investigate the effects of treatment with 5-ALA plus sodium ferrous citrate (SFC) to patients with MDM on their glucose tolerance. A total of 5 patients with MDM will be administered 5-ALA/SFC (200 mg/d) for 24 weeks. We will perform a 75-g oral glucose tolerance test before and at 24 weeks after the start of this 5-ALA/SFC treatment to evaluate glucose-dependent insulin responses. DISCUSSION: To the best of our knowledge, this study will be the first assessment of the effects of 5-ALA/SFC in patients with MDM. This study will obtain an evidence regarding the effectiveness and safety of 5-ALA/SFC for patients with MDM. TRIAL REGISTRATION: This study was registered with the University Hospital Medical Information Network (UMIN000040581) on July 1, 2020 and with the Japan Registry of Clinical Trials (jRCTs071200025) on August 3, 2020.


Assuntos
Surdez/tratamento farmacológico , Diabetes Mellitus Tipo 2/tratamento farmacológico , Compostos Ferrosos/administração & dosagem , Intolerância à Glucose/tratamento farmacológico , Insulina/administração & dosagem , Ácidos Levulínicos/administração & dosagem , Doenças Mitocondriais/tratamento farmacológico , Trifosfato de Adenosina/metabolismo , Adulto , Glicemia/análise , Surdez/sangue , Surdez/diagnóstico , Surdez/patologia , Diabetes Mellitus Tipo 2/sangue , Diabetes Mellitus Tipo 2/diagnóstico , Diabetes Mellitus Tipo 2/patologia , Quimioterapia Combinada/efeitos adversos , Quimioterapia Combinada/métodos , Feminino , Compostos Ferrosos/efeitos adversos , Intolerância à Glucose/sangue , Intolerância à Glucose/diagnóstico , Intolerância à Glucose/patologia , Teste de Tolerância a Glucose , Humanos , Japão , Ácidos Levulínicos/efeitos adversos , Masculino , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/patologia , Doenças Mitocondriais/sangue , Doenças Mitocondriais/diagnóstico , Doenças Mitocondriais/patologia , Projetos Piloto , Resultado do Tratamento
3.
Nat Metab ; 3(1): 33-42, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33462515

RESUMO

Mitochondrial diseases (MDs) are a heterogeneous group of disorders resulting from mutations in nuclear or mitochondrial DNA genes encoding mitochondrial proteins1,2. MDs cause pathologies with severe tissue damage and ultimately death3,4. There are no cures for MDs and current treatments are only palliative5-7. Here we show that tetracyclines improve fitness of cultured MD cells and ameliorate disease in a mouse model of Leigh syndrome. To identify small molecules that prevent cellular damage and death under nutrient stress conditions, we conduct a chemical high-throughput screen with cells carrying human MD mutations and discover a series of antibiotics that maintain survival of various MD cells. We subsequently show that a sub-library of tetracycline analogues, including doxycycline, rescues cell death and inflammatory signatures in mutant cells through partial and selective inhibition of mitochondrial translation, resulting in an ATF4-independent mitohormetic response. Doxycycline treatment strongly promotes fitness and survival of Ndufs4-/- mice, a preclinical Leigh syndrome mouse model8. A proteomic analysis of brain tissue reveals that doxycycline treatment largely prevents neuronal death and the accumulation of neuroimmune and inflammatory proteins in Ndufs4-/- mice, indicating a potential causal role for these proteins in the brain pathology. Our findings suggest that tetracyclines deserve further evaluation as potential drugs for the treatment of MDs.


Assuntos
Antibacterianos/uso terapêutico , Doenças Mitocondriais/tratamento farmacológico , Tetraciclinas/uso terapêutico , Fator 4 Ativador da Transcrição/metabolismo , Animais , Encéfalo/patologia , Células Cultivadas , Modelos Animais de Doenças , Complexo I de Transporte de Elétrons/genética , Complexo I de Transporte de Elétrons/metabolismo , Ensaios de Triagem em Larga Escala , Humanos , Doença de Leigh/tratamento farmacológico , Doença de Leigh/patologia , Expectativa de Vida , Metabolômica , Camundongos , Camundongos Knockout , Doenças Mitocondriais/mortalidade , Doenças Mitocondriais/patologia , Aptidão Física , Análise de Sobrevida
4.
Int J Mol Sci ; 21(24)2020 Dec 19.
Artigo em Inglês | MEDLINE | ID: mdl-33352696

RESUMO

COASY protein-associated neurodegeneration (CoPAN) is a rare but devastating genetic autosomal recessive disorder of inborn error of CoA metabolism, which shares with pantothenate kinase-associated neurodegeneration (PKAN) similar features, such as dystonia, parkinsonian traits, cognitive impairment, axonal neuropathy, and brain iron accumulation. These two disorders are part of the big group of neurodegenerations with brain iron accumulation (NBIA) for which no effective treatment is available at the moment. To date, the lack of a mammalian model, fully recapitulating the human disorder, has prevented the elucidation of pathogenesis and the development of therapeutic approaches. To gain new insights into the mechanisms linking CoA metabolism, iron dyshomeostasis, and neurodegeneration, we generated and characterized the first CoPAN disease mammalian model. Since CoA is a crucial metabolite, constitutive ablation of the Coasy gene is incompatible with life. On the contrary, a conditional neuronal-specific Coasy knock-out mouse model consistently developed a severe early onset neurological phenotype characterized by sensorimotor defects and dystonia-like movements, leading to premature death. For the first time, we highlighted defective brain iron homeostasis, elevation of iron, calcium, and magnesium, together with mitochondrial dysfunction. Surprisingly, total brain CoA levels were unchanged, and no signs of neurodegeneration were present.


Assuntos
Coenzima A Ligases/fisiologia , Hemocromatose/patologia , Ferro/metabolismo , Doenças Mitocondriais/patologia , Transtornos Motores/patologia , Neurodegeneração Associada a Pantotenato-Quinase/complicações , Sinapsinas/fisiologia , Animais , Coenzima A/metabolismo , Feminino , Hemocromatose/etiologia , Homeostase , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Mitocôndrias/genética , Mitocôndrias/metabolismo , Mitocôndrias/patologia , Doenças Mitocondriais/etiologia , Doenças Mitocondriais/metabolismo , Transtornos Motores/etiologia , Transtornos Motores/metabolismo
5.
Inflamm Res ; 69(11): 1077-1085, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32767095

RESUMO

BACKGROUND: Decline in mitochondrial function occurs with aging and may increase mortality. We discuss mitochondrial contribution to Covid-19 sepsis, specifically the complex interaction of innate immune function, viral replication, hyper-inflammatory state, and HIF-α/Sirtuin pathways. METHODS: Articles from PubMed/Medline searches were reviewed using the combination of terms "SARS-CoV-2, Covid-19, sepsis, mitochondria, aging, and immunometabolism". RESULTS: Evidence indicates that mitochondria in senescent cells may be dysfunctional and unable to keep up with hypermetabolic demands associated with Covid-19 sepsis. Mitochondrial proteins may serve as damage-associated molecular pattern (DAMP) activating innate immunity. Disruption in normal oxidative phosphorylation pathways contributes to elevated ROS which activates sepsis cascade through HIF-α/Sirtuin pathway. Viral-mitochondrial interaction may be necessary for replication and increased viral load. Hypoxia and hyper-inflammatory state contribute to increased mortality associated with Covid-19 sepsis. CONCLUSIONS: Aging is associated with worse outcomes in sepsis. Modulating Sirtuin activity is emerging as therapeutic agent in sepsis. HIF-α, levels of mitochondrial DNA, and other mitochondrial DAMP molecules may also serve as useful biomarker and need to be investigated. These mechanisms should be explored specifically for Covid-19-related sepsis. Understanding newly discovered regulatory mechanisms may lead to the development of novel diagnostic and therapeutic targets.


Assuntos
Infecções por Coronavirus/complicações , Infecções por Coronavirus/patologia , Inflamação/etiologia , Inflamação/patologia , Mitocôndrias/metabolismo , Mitocôndrias/patologia , Doenças Mitocondriais/etiologia , Doenças Mitocondriais/patologia , Pneumonia Viral/complicações , Pneumonia Viral/patologia , Sepse/etiologia , Sepse/patologia , Envelhecimento , Infecções por Coronavirus/mortalidade , Humanos , Inflamação/mortalidade , Doenças Mitocondriais/mortalidade , Pandemias , Pneumonia Viral/mortalidade , Sepse/mortalidade
6.
Nat Commun ; 11(1): 4269, 2020 08 28.
Artigo em Inglês | MEDLINE | ID: mdl-32859890

RESUMO

Mitochondria generate most cellular energy via oxidative phosphorylation. Twenty-two species of mitochondrial (mt-)tRNAs encoded in mtDNA translate essential subunits of the respiratory chain complexes. mt-tRNAs contain post-transcriptional modifications introduced by nuclear-encoded tRNA-modifying enzymes. They are required for deciphering genetic code accurately, as well as stabilizing tRNA. Loss of tRNA modifications frequently results in severe pathological consequences. Here, we perform a comprehensive analysis of post-transcriptional modifications of all human mt-tRNAs, including 14 previously-uncharacterized species. In total, we find 18 kinds of RNA modifications at 137 positions (8.7% in 1575 nucleobases) in 22 species of human mt-tRNAs. An up-to-date list of 34 genes responsible for mt-tRNA modifications are provided. We identify two genes required for queuosine (Q) formation in mt-tRNAs. Our results provide insight into the molecular mechanisms underlying the decoding system and could help to elucidate the molecular pathogenesis of human mitochondrial diseases caused by aberrant tRNA modifications.


Assuntos
Processamento Pós-Transcricional do RNA , RNA Mitocondrial/química , RNA de Transferência/química , Feminino , Código Genético , Células HEK293 , Células HeLa , Humanos , Espectrometria de Massas , Mitocôndrias/metabolismo , Mitocôndrias/patologia , Doenças Mitocondriais/genética , Doenças Mitocondriais/patologia , Estrutura Molecular , Nucleosídeo Q/biossíntese , Nucleosídeo Q/química , Fosforilação Oxidativa , Placenta , Gravidez , RNA Mitocondrial/isolamento & purificação , RNA Mitocondrial/metabolismo , RNA de Transferência/isolamento & purificação , RNA de Transferência/metabolismo , RNA-Seq
7.
DNA Cell Biol ; 39(8): 1431-1443, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32598172

RESUMO

Mitochondria contain their own genome, mitochondrial DNA (mtDNA), essential to support their fundamental intracellular role in ATP production and other key metabolic and homeostatic pathways. Mitochondria are highly dynamic organelles that communicate with all the other cellular compartments, through sites of high physical proximity. Among all, their crosstalk with the endoplasmic reticulum (ER) appears particularly important as its derangement is tightly implicated with several human disorders. Population-specific mtDNA variants clustered in defining the haplogroups have been shown to exacerbate or mitigate these pathological conditions. The exact mechanisms of the mtDNA background-modifying effect are not completely clear and a possible explanation is the outcome of mitochondrial efficiency on retrograde signaling to the nucleus. However, the possibility that different haplogroups shape the proximity and crosstalk between mitochondria and the ER has never been proposed neither investigated. In this study, we pose and discuss this question and provide preliminary data to answer it. Besides, we also address the possibility that single, disease-causing mtDNA point mutations may act also by reshaping organelle communication. Overall, this perspective review provides a theoretical platform for future studies on the interaction between mtDNA variants and organelle contact sites.


Assuntos
DNA Mitocondrial/genética , Retículo Endoplasmático/genética , Mitocôndrias/genética , Doenças Mitocondriais/genética , Trifosfato de Adenosina/genética , Trifosfato de Adenosina/metabolismo , Genoma Mitocondrial/genética , Humanos , Mitocôndrias/patologia , Doenças Mitocondriais/patologia
8.
AJNR Am J Neuroradiol ; 41(5): 917-922, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32381541

RESUMO

Pathogenic variants in the polymerase γ gene (POLG) cause a diverse group of pathologies known as POLG-related disorders. In this report, we describe brain MR imaging findings and electroencephalogram correlates of 13 children with POLG-related disorders at diagnosis and follow-up. At diagnosis, all patients had seizures and 12 had abnormal MR imaging findings. The most common imaging findings were unilateral or bilateral perirolandic (54%) and unilateral or bilateral thalamic signal changes (77%). Association of epilepsia partialis continua with perirolandic and thalamic signal changes was present in 86% and 70% of the patients, respectively. The occipital lobe was affected in 2 patients. On follow-up, 92% of the patients had disease progression or fatal outcome. Rapid volume loss was seen in 77% of the patients. The occipital lobe (61%) and thalamus (61%) were the most affected brain regions. Perirolandic signal changes and seizures may represent a brain imaging biomarker of early-onset pediatric POLG-related disorders.


Assuntos
Encéfalo/diagnóstico por imagem , Doenças Mitocondriais/diagnóstico por imagem , Neuroimagem/métodos , Convulsões/diagnóstico por imagem , Convulsões/genética , Encéfalo/patologia , Criança , Pré-Escolar , Polimerase do DNA Mitocondrial/genética , Eletroencefalografia , Feminino , Humanos , Imagem por Ressonância Magnética , Masculino , Doenças Mitocondriais/genética , Doenças Mitocondriais/patologia , Estudos Retrospectivos , Convulsões/patologia
9.
Sci Rep ; 10(1): 8554, 2020 05 22.
Artigo em Inglês | MEDLINE | ID: mdl-32444699

RESUMO

The high-energy demands of the retina are thought to contribute to its particular vulnerability to mitochondrial dysfunction. Photoreceptors are the cells with the higher oxygen consumption within the retina, and among these, the cones contain more mitochondria and have a higher energy demand than rods. A cohort of twenty-two patients with genetically-defined mitochondrial diseases (MDs) were enrolled to determine if the macula is functionally and anatomically impaired in these metabolic disorders. Visual acuity and fERG amplitude of patients with primary mitochondrial dysfunction were reduced compared to controls. Furthermore, SD-OCT layer segmentation showed a reduction of retinal and outer nuclear layer (ONL) volume in the macula of the patients. fERG amplitude showed a positive correlation with both ONL volume and thickness. A negative relationship was noted between fERG amplitude and disease severity assessed with Newcastle Mitochondrial Disease Adult Scale. In conclusion, MDs are associated with functional and anatomical alteration of macular cone system, characterized by its strong correlation with clinical disease severity suggesting a role as a potential biomarker of primary mitochondrial disorders.


Assuntos
Biomarcadores/análise , Macula Lutea/fisiopatologia , Degeneração Macular/fisiopatologia , Doenças Mitocondriais/patologia , Retina/fisiopatologia , Células Fotorreceptoras Retinianas Cones/patologia , Índice de Gravidade de Doença , Adulto , Estudos de Coortes , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Doenças Mitocondriais/etiologia , Acuidade Visual , Adulto Jovem
10.
Sci Rep ; 10(1): 4308, 2020 03 09.
Artigo em Inglês | MEDLINE | ID: mdl-32152380

RESUMO

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease for which the pathophysiological mechanisms of motor neuron loss are not precisely clarified. Environmental and epigenetic mechanisms such as microRNAs (miRNAs) could have a role in disease progression. We studied the expression pattern of miRNAs in ALS serum from 60 patients and 29 healthy controls. We also analyzed how deregulated miRNAs found in serum affected cellular pathways such as apoptosis, autophagy and mitochondrial physiology in SH-SY5Y cells. We found that miR-335-5p was downregulated in ALS serum. SH-SY5Y cells were transfected with a specific inhibitor of miR-335-5p and showed abnormal mitochondrial morphology, with an increment of reactive species of oxygen and superoxide dismutase activity. Pro-apoptotic caspases-3 and 7 also showed an increased activity in transfected cells. The downregulation of miR-335-5p, which has an effect on mitophagy, autophagy and apoptosis in SH-SY5Y neuronal cells could have a role in the motor neuron loss observed in ALS.


Assuntos
Esclerose Amiotrófica Lateral/patologia , Apoptose , Biomarcadores Tumorais/genética , Regulação Neoplásica da Expressão Gênica , MicroRNAs/genética , Doenças Mitocondriais/patologia , Doenças Neurodegenerativas/patologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Esclerose Amiotrófica Lateral/complicações , Esclerose Amiotrófica Lateral/genética , Autofagia , Estudos de Casos e Controles , Progressão da Doença , Regulação para Baixo , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Doenças Mitocondriais/complicações , Doenças Mitocondriais/genética , Doenças Neurodegenerativas/complicações , Doenças Neurodegenerativas/genética , Prognóstico , Células Tumorais Cultivadas
11.
Biochim Biophys Acta Mol Basis Dis ; 1866(6): 165725, 2020 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-32061778

RESUMO

PURPOSE: Newborns who test positive for very long-chain acyl-CoA dehydrogenase deficiency (VLCADD) in newborn screening may have a severe phenotype with early onset of life-threatening symptoms but may also have an attenuated phenotype and never become symptomatic. The objective of this study is to investigate whether metabolomic profiles in dried bloodspots (DBS) of newborns allow early phenotypic prediction, permitting tailored treatment and follow-up. METHODS: A metabolic fingerprint was generated by direct infusion high resolution mass spectrometry in DBS of VLCADD patients (n = 15) and matched controls. Multivariate analysis of the metabolomic profiles was applied to differentiate subgroups. RESULTS: Concentration of six acylcarnitine species differed significantly between patients and controls. The concentration of C18:2- and C20:0-carnitine, 13,14-dihydroretinol and deoxycytidine monophosphate allowed separation between mild and severe patients. Two patients who could not be prognosticated on early clinical symptoms, were correctly fitted for severity in the score plot based on the untargeted metabolomics. CONCLUSION: Distinctive metabolomic profiles in DBS of newborns with VLCADD may allow phenotypic prognostication. The full potential of this approach as well as the underlying biochemical mechanisms need further investigation.


Assuntos
Acil-CoA Desidrogenase de Cadeia Longa/deficiência , Carnitina/análogos & derivados , Síndrome Congênita de Insuficiência da Medula Óssea/sangue , Erros Inatos do Metabolismo Lipídico/sangue , Metabolômica , Doenças Mitocondriais/sangue , Doenças Musculares/sangue , Triagem Neonatal , Acil-CoA Desidrogenase de Cadeia Longa/sangue , Acil-CoA Desidrogenase de Cadeia Longa/genética , Carnitina/metabolismo , Criança , Pré-Escolar , Síndrome Congênita de Insuficiência da Medula Óssea/patologia , Teste em Amostras de Sangue Seco/métodos , Feminino , Humanos , Lactente , Recém-Nascido , Erros Inatos do Metabolismo Lipídico/patologia , Masculino , Espectrometria de Massas , Doenças Mitocondriais/patologia , Doenças Musculares/patologia , Fenótipo
13.
J Neurosci ; 40(9): 1975-1986, 2020 02 26.
Artigo em Inglês | MEDLINE | ID: mdl-32005765

RESUMO

Mitochondrial dysfunction is critically involved in Parkinson's disease, characterized by loss of dopaminergic neurons (DaNs) in the substantia nigra (SNc), whereas DaNs in the neighboring ventral tegmental area (VTA) are much less affected. In contrast to VTA, SNc DaNs engage calcium channels to generate action potentials, which lead to oxidant stress by yet unknown pathways. To determine the molecular mechanisms linking calcium load with selective cell death in the presence of mitochondrial deficiency, we analyzed the mitochondrial redox state and the mitochondrial membrane potential in mice of both sexes with genetically induced, severe mitochondrial dysfunction in DaNs (MitoPark mice), at the same time expressing a redox-sensitive GFP targeted to the mitochondrial matrix. Despite mitochondrial insufficiency in all DaNs, exclusively SNc neurons showed an oxidized redox-system, i.e., a low reduced/oxidized glutathione (GSH-GSSG) ratio. This was mimicked by cyanide, but not by rotenone or antimycin A, making the involvement of reactive oxygen species rather unlikely. Surprisingly, a high mitochondrial inner membrane potential was maintained in MitoPark SNc DaNs. Antagonizing calcium influx into the cell and into mitochondria, respectively, rescued the disturbed redox ratio and induced further hyperpolarization of the inner mitochondrial membrane. Our data therefore show that the constant calcium load in SNc DaNs is counterbalanced by a high mitochondrial inner membrane potential, even under conditions of severe mitochondrial dysfunction, but triggers a detrimental imbalance in the mitochondrial redox system, which will lead to neuron death. Our findings thus reveal a new mechanism, redox imbalance, which underlies the differential vulnerability of DaNs to mitochondrial defects.SIGNIFICANCE STATEMENT Parkinson's disease is characterized by the preferential degeneration of dopaminergic neurons (DaNs) of the substantia nigra pars compacta (SNc), resulting in the characteristic hypokinesia in patients. Ubiquitous pathological triggers cannot be responsible for the selective neuron loss. Here we show that mitochondrial impairment together with elevated calcium burden destabilize the mitochondrial antioxidant defense only in SNc DaNs, and thus promote the increased vulnerability of this neuron population.


Assuntos
Antioxidantes/metabolismo , Cálcio/toxicidade , Neurônios Dopaminérgicos/metabolismo , Neurônios Dopaminérgicos/patologia , Doenças Mitocondriais/metabolismo , Doenças Mitocondriais/patologia , Substância Negra/metabolismo , Substância Negra/patologia , Animais , Calbindina 1/metabolismo , Morte Celular , Cianetos/toxicidade , Feminino , Masculino , Potencial da Membrana Mitocondrial , Camundongos , Membranas Mitocondriais/metabolismo , Oxirredução , Estresse Oxidativo , Área Tegmentar Ventral/metabolismo , Área Tegmentar Ventral/patologia
14.
Am J Hum Genet ; 106(2): 272-279, 2020 02 06.
Artigo em Inglês | MEDLINE | ID: mdl-32004445

RESUMO

Recent studies have identified both recessive and dominant forms of mitochondrial disease that result from ATAD3A variants. The recessive form includes subjects with biallelic deletions mediated by non-allelic homologous recombination. We report five unrelated neonates with a lethal metabolic disorder characterized by cardiomyopathy, corneal opacities, encephalopathy, hypotonia, and seizures in whom a monoallelic reciprocal duplication at the ATAD3 locus was identified. Analysis of the breakpoint junction fragment indicated that these 67 kb heterozygous duplications were likely mediated by non-allelic homologous recombination at regions of high sequence identity in ATAD3A exon 11 and ATAD3C exon 7. At the recombinant junction, the duplication allele produces a fusion gene derived from ATAD3A and ATAD3C, the protein product of which lacks key functional residues. Analysis of fibroblasts derived from two affected individuals shows that the fusion gene product is expressed and stable. These cells display perturbed cholesterol and mitochondrial DNA organization similar to that observed for individuals with severe ATAD3A deficiency. We hypothesize that the fusion protein acts through a dominant-negative mechanism to cause this fatal mitochondrial disorder. Our data delineate a molecular diagnosis for this disorder, extend the clinical spectrum associated with structural variation at the ATAD3 locus, and identify a third mutational mechanism for ATAD3 gene cluster variants. These results further affirm structural variant mutagenesis mechanisms in sporadic disease traits, emphasize the importance of copy number analysis in molecular genomic diagnosis, and highlight some of the challenges of detecting and interpreting clinically relevant rare gene rearrangements from next-generation sequencing data.


Assuntos
ATPases Associadas a Diversas Atividades Celulares/genética , Colesterol/metabolismo , Duplicação Gênica , Recombinação Homóloga , Proteínas de Membrana/genética , Mitocôndrias/patologia , Doenças Mitocondriais/patologia , Proteínas Mitocondriais/genética , ATPases Associadas a Diversas Atividades Celulares/química , Sequência de Aminoácidos , Encefalopatias/etiologia , Encefalopatias/metabolismo , Encefalopatias/patologia , Cardiomiopatias/etiologia , Cardiomiopatias/metabolismo , Cardiomiopatias/patologia , Opacidade da Córnea/etiologia , Opacidade da Córnea/metabolismo , Opacidade da Córnea/patologia , Variações do Número de Cópias de DNA , Feminino , Rearranjo Gênico , Humanos , Lactente , Recém-Nascido , Masculino , Proteínas de Membrana/química , Mitocôndrias/genética , Mitocôndrias/metabolismo , Doenças Mitocondriais/genética , Doenças Mitocondriais/metabolismo , Proteínas Mitocondriais/química , Hipotonia Muscular/etiologia , Hipotonia Muscular/metabolismo , Hipotonia Muscular/patologia , Mutação , Conformação Proteica , Convulsões/etiologia , Convulsões/metabolismo , Convulsões/patologia , Homologia de Sequência
15.
Biochim Biophys Acta Mol Basis Dis ; 1866(6): 165727, 2020 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-32070771

RESUMO

Mitochondrial complex I (CI), the first multiprotein enzyme complex of the OXPHOS system, executes a major role in cellular ATP generation. Consequently, dysfunction of this complex has been linked to inherited metabolic disorders, including Leigh disease (LD), an often fatal disease in early life. Development of clinical effective treatments for LD remains challenging due to the complex pathophysiological nature. Treatment with the peroxisome proliferation-activated receptor (PPAR) agonist bezafibrate improved disease phenotype in several mitochondrial disease mouse models mediated via enhanced mitochondrial biogenesis and fatty acid ß-oxidation. However, the therapeutic potential of this mixed PPAR (α, δ/ß, γ) agonist is severely hampered by hepatotoxicity, which is possibly caused by activation of PPARγ. Here, we aimed to investigate the effects of the PPARα-specific fibrate clofibrate in mitochondrial CI-deficient (Ndufs4-/-) mice. Clofibrate increased lifespan and motor function of Ndufs4-/- mice, while only marginal hepatotoxic effects were observed. Due to the complex clinical and cellular phenotype of CI-deficiency, we also aimed to investigate the therapeutic potential of clofibrate combined with the redox modulator KH176. As described previously, single treatment with KH176 was beneficial, however, combining clofibrate with KH176 did not result in an additive effect on disease phenotype in Ndufs4-/- mice. Overall, both drugs have promising, but independent and nonadditive, properties for the pharmacological treatment of CI-deficiency-related mitochondrial diseases.


Assuntos
Cromanos/farmacologia , Clofibrato/farmacologia , Complexo I de Transporte de Elétrons/deficiência , Longevidade/efeitos dos fármacos , Doenças Mitocondriais/tratamento farmacológico , Trifosfato de Adenosina/metabolismo , Animais , Bezafibrato/farmacologia , Complexo I de Transporte de Elétrons/genética , Complexo I de Transporte de Elétrons/metabolismo , Ácidos Graxos/metabolismo , Humanos , Doença de Leigh/tratamento farmacológico , Doença de Leigh/metabolismo , Doença de Leigh/patologia , Camundongos , Camundongos Knockout , Mitocôndrias/efeitos dos fármacos , Doenças Mitocondriais/metabolismo , Doenças Mitocondriais/patologia , Atividade Motora/efeitos dos fármacos , Oxirredução/efeitos dos fármacos , Receptores Ativados por Proliferador de Peroxissomo/agonistas , Receptores Ativados por Proliferador de Peroxissomo/genética
16.
Nat Commun ; 11(1): 970, 2020 02 20.
Artigo em Inglês | MEDLINE | ID: mdl-32080200

RESUMO

Deregulation of mitochondrial network in terminally differentiated cells contributes to a broad spectrum of disorders. Methylmalonic acidemia (MMA) is one of the most common inherited metabolic disorders, due to deficiency of the mitochondrial methylmalonyl-coenzyme A mutase (MMUT). How MMUT deficiency triggers cell damage remains unknown, preventing the development of disease-modifying therapies. Here we combine genetic and pharmacological approaches to demonstrate that MMUT deficiency induces metabolic and mitochondrial alterations that are exacerbated by anomalies in PINK1/Parkin-mediated mitophagy, causing the accumulation of dysfunctional mitochondria that trigger epithelial stress and ultimately cell damage. Using drug-disease network perturbation modelling, we predict targetable pathways, whose modulation repairs mitochondrial dysfunctions in patient-derived cells and alleviate phenotype changes in mmut-deficient zebrafish. These results suggest a link between primary MMUT deficiency, diseased mitochondria, mitophagy dysfunction and epithelial stress, and provide potential therapeutic perspectives for MMA.


Assuntos
Erros Inatos do Metabolismo dos Aminoácidos/metabolismo , Erros Inatos do Metabolismo dos Aminoácidos/patologia , Erros Inatos do Metabolismo/metabolismo , Erros Inatos do Metabolismo/patologia , Metilmalonil-CoA Mutase/deficiência , Doenças Mitocondriais/metabolismo , Doenças Mitocondriais/patologia , Mitofagia/fisiologia , Alquil e Aril Transferases/deficiência , Alquil e Aril Transferases/genética , Erros Inatos do Metabolismo dos Aminoácidos/genética , Animais , Modelos Animais de Doenças , Células Epiteliais/metabolismo , Células Epiteliais/patologia , Feminino , Técnicas de Inativação de Genes , Humanos , Masculino , Proteínas de Membrana/deficiência , Proteínas de Membrana/genética , Erros Inatos do Metabolismo/genética , Metilmalonil-CoA Mutase/genética , Metilmalonil-CoA Mutase/metabolismo , Camundongos , Camundongos Knockout , Doenças Mitocondriais/genética , Mitofagia/genética , Proteínas Quinases/genética , Proteínas Quinases/metabolismo , Estresse Fisiológico , Ubiquitina-Proteína Ligases/genética , Ubiquitina-Proteína Ligases/metabolismo , Peixe-Zebra
17.
J Hum Genet ; 65(3): 231-240, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31907385

RESUMO

TOM70 is a member of the TOM complex that transports cytosolic proteins into mitochondria. Here, we identified two compound heterozygous variants in TOMM70 [c.794C>T (p.T265M) and c.1745C>T (p.A582V)] from a patient with severe anemia, lactic acidosis, and developmental delay. Patient-derived immortalized lymphocytes showed decreased TOM70 expression, oligomerized TOM70 complex, and TOM 20/22/40 complex compared with expression in control lymphocytes. Functional analysis revealed that patient-derived cells exhibited multi-oxidative phosphorylation system (OXPHOS) complex defects, with complex IV being primarily affected. As a result, patient-derived cells grew slower in galactose medium and generated less ATP and more extracellular lactic acid than did control cells. In vitro cell model compensatory experiments confirmed the pathogenicity of TOMM70 variants since only wild-type TOM70, but not mutant TOM70, could restore the complex IV defect and TOM70 expression in TOM70 knockdown U2OS cells. Altogether, we report the first case of mitochondrial disease-causing mutations in TOMM70 and demonstrate that TOM70 is essential for multi-OXPHOS assembly. Mutational screening of TOMM70 should be employed to identify mitochondrial disease-causing gene mutations in the future.


Assuntos
Acidose Láctica/genética , Anemia/genética , Deficiências do Desenvolvimento/genética , Proteínas de Transporte da Membrana Mitocondrial/genética , Acidose Láctica/patologia , Anemia/patologia , Criança , Deficiências do Desenvolvimento/patologia , Humanos , Masculino , Mitocôndrias/genética , Doenças Mitocondriais/genética , Doenças Mitocondriais/patologia , Mutação/genética , Fosforilação Oxidativa , Sequenciamento Completo do Exoma
18.
Am J Physiol Cell Physiol ; 318(2): C380-C391, 2020 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-31913702

RESUMO

Children surviving cancer and chemotherapy are at risk for adverse health events including heart failure that may be delayed by years. Although the early effects of doxorubicin-induced cardiotoxicity may be attributed to a direct effect on the cardiomyocytes, the mechanisms underlying the delayed or late effects (8-20 yr) are unknown. The goal of this project was to develop a model of late-onset doxorubicin-induced cardiotoxicity to better delineate the underlying pathophysiology responsible. The underlying hypothesis was that doxorubicin-induced "late-onset cardiotoxicity" was the result of mitochondrial dysfunction leading to cell failure and death. Wistar rats, 3-4 wk of age, were randomly assigned to vehicle or doxorubicin injection groups (1-45 mg/kg). Cardiovascular function was unaltered at the lower dosages (1-15 kg/mg), but beginning at 6 mo after injection significant cardiac degradation was observed in the 45 mg/kg group. Doxorubicin significantly increased myocardial mitochondrial DNA (mtDNA) damage. In contrast, in isolated c-kit left ventricular (LV) cells, doxorubicin treatment did not increase mtDNA damage. Biomarkers of senescence within the LV were significantly increased, suggesting accelerated aging of the LV. Doxorubicin also significantly increased LV histamine content suggestive of mast cell activation. With the use of flow cytometry, a significant expansion of the c-kit and stage-specific embryonic antigen 1 cell populations within the LV were concomitant with significant decreases in the circulating peripheral blood population of these cells. These results are consistent with the concept that doxorubicin induced significant damage to the cardiomyocyte population and that although the heart attempted to compensate it eventually succumbed to an inability for self-repair.


Assuntos
Cardiotoxicidade/patologia , Senescência Celular/efeitos dos fármacos , Doxorrubicina/farmacologia , Miócitos Cardíacos/efeitos dos fármacos , Miócitos Cardíacos/patologia , Animais , Linhagem Celular , DNA Mitocondrial/efeitos dos fármacos , Ventrículos do Coração/efeitos dos fármacos , Ventrículos do Coração/patologia , Doenças Mitocondriais/induzido quimicamente , Doenças Mitocondriais/patologia , Ratos , Ratos Wistar
19.
FASEB J ; 34(1): 303-315, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31914648

RESUMO

Mutations in succinate dehydrogenase (SDH) lead to the development of tumors in a restricted subset of cell types, including chromaffin cells and paraganglia. The molecular basis for this specificity is currently unknown. We show that loss of SDH activity in a chromaffin cell model does not perturb complex I function, retaining the ability to oxidize NADH within the electron transport chain. This activity supports continued oxidation of substrates within the tricarboxylic acid (TCA) cycle. However, due to the block in the TCA cycle at SDH, the high glutamine oxidation activity is only maintained through an efflux of succinate. We also show that although the mitochondria of SDH-deficient cells are less active per se, their higher mass per cell results in an overall respiratory rate that is comparable with wild-type cells. Finally, we observed that when their mitochondria are uncoupled, SDH-deficient cells are unable to preserve their viability, suggesting that the mitochondrial metabolic network is unable to compensate when exposed to additional stress. We therefore show that in contrast to models of SDH deficiency based on epithelial cells, a chromaffin cell model retains aspects of metabolic "health," which could form the basis of cell specificity of this rare tumor type.


Assuntos
Células Cromafins/metabolismo , Complexo I de Transporte de Elétrons/metabolismo , Mitocôndrias/metabolismo , Doenças Mitocondriais/metabolismo , Neoplasias/metabolismo , Succinato Desidrogenase/fisiologia , Animais , Células Cromafins/patologia , Humanos , Masculino , Camundongos , Camundongos Knockout , Mitocôndrias/patologia , Doenças Mitocondriais/patologia , Mutação , NAD/metabolismo , Neoplasias/patologia , Succinato Desidrogenase/genética , Succinato Desidrogenase/metabolismo , Transcriptoma
20.
J Neuroinflammation ; 17(1): 36, 2020 Jan 27.
Artigo em Inglês | MEDLINE | ID: mdl-31987040

RESUMO

BACKGROUND: Out of the myriad of complications associated with septic shock, septic-associated encephalopathy (SAE) carries a significant risk of morbidity and mortality. Blood-brain-barrier (BBB) impairment, which subsequently leads to increased vascular permeability, has been associated with neuronal injury in sepsis. Thus, preventing BBB damage is an attractive therapeutic target. Mitochondrial dysfunction is an important contributor of sepsis-induced multi-organ system failure. More recently, mitochondrial dysfunction in endothelial cells has been implicated in mediating BBB failure in stroke, multiple sclerosis and in other neuroinflammatory disorders. Here, we focused on Drp1-mediated mitochondrial dysfunction in endothelial cells as a potential target to prevent BBB failure in sepsis. METHODS: We used lipopolysaccharide (LPS) to induce inflammation and BBB disruption in a cell culture as well as in murine model of sepsis. BBB disruption was assessed by measuring levels of key tight-junction proteins. Brain cytokines levels, oxidative stress markers, and activity of mitochondrial complexes were measured using biochemical assays. Astrocyte and microglial activation were measured using immunoblotting and qPCR. Transwell cultures of brain microvascular endothelial cells co-cultured with astrocytes were used to assess the effect of LPS on expression of tight-junction proteins, mitochondrial function, and permeability to fluorescein isothiocyanate (FITC) dextran. Finally, primary neuronal cultures exposed to LPS were assessed for mitochondrial dysfunction. RESULTS: LPS induced a strong brain inflammatory response and oxidative stress in mice which was associated with increased Drp1 activation and mitochondrial localization. Particularly, Drp1-(Fission 1) Fis1-mediated oxidative stress also led to an increase in expression of vascular permeability regulators in the septic mice. Similarly, mitochondrial defects mediated via Drp1-Fis1 interaction in primary microvascular endothelial cells were associated with increased BBB permeability and loss of tight-junctions after acute LPS injury. P110, an inhibitor of Drp1-Fis1 interaction, abrogated these defects, thus indicating a critical role for this interaction in mediating sepsis-induced brain dysfunction. Finally, LPS mediated a direct toxic effect on primary cortical neurons, which was abolished by P110 treatment. CONCLUSIONS: LPS-induced impairment of BBB appears to be dependent on Drp1-Fis1-mediated mitochondrial dysfunction. Inhibition of mitochondrial dysfunction with P110 may have potential therapeutic significance in septic encephalopathy.


Assuntos
Barreira Hematoencefálica/patologia , Encefalopatias/patologia , Dinaminas/genética , Doenças Mitocondriais/genética , Doenças Mitocondriais/patologia , Sepse/patologia , Animais , Encefalopatias/induzido quimicamente , Células Cultivadas , Citocinas/metabolismo , Células Endoteliais/metabolismo , Células Endoteliais/patologia , Lipopolissacarídeos , Ativação de Macrófagos , Camundongos , Camundongos Endogâmicos BALB C , Neuroglia/patologia , Estresse Oxidativo , Cultura Primária de Células , Proteínas de Junções Íntimas/biossíntese , Proteínas de Junções Íntimas/genética
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