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2.
PLoS One ; 15(10): e0239860, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33085679

RESUMO

Leigh Syndrome French Canadian (LSFC) is a rare autosomal recessive metabolic disorder characterized by severe lactic acidosis crises and early mortality. LSFC patients carry mutations in the Leucine Rich Pentatricopeptide Repeat Containing (LRPPRC) gene, which lead to defects in the respiratory chain complexes and mitochondrial dysfunction. Mitochondrial respiration modulates cellular metabolic activity, which impacts many cell types including the differentiation and function of immune cells. Hence, we postulated that, in addition to neurological and metabolic disorders, LSFC patients may show impaired immune activity. To gain insight into the quality of the immune response in LSFC patients, we examined the response to the measles, mumps and rubella (MMR) vaccine by measuring antibody titers to MMR in the plasma. In a cohort of eight LSFC patients, the response to the MMR vaccine was variable, with some individuals showing antibodies to all three viruses, while others had antibodies to two or fewer viruses. These results suggest that the mutations in the LRPPRC gene present in LSFC patients may affect the immune response to vaccines. Monitoring vaccine response in this fragile population should be considered to ensure full protection against pathogens.


Assuntos
Imunogenicidade da Vacina , Doença de Leigh/imunologia , Vacina contra Sarampo-Caxumba-Rubéola/imunologia , Adolescente , Adulto , Anticorpos Antivirais/sangue , Anticorpos Antivirais/imunologia , Criança , Feminino , Humanos , Doença de Leigh/epidemiologia , Doença de Leigh/genética , Masculino , Proteínas de Neoplasias/genética , Quebeque , Vacinação/estatística & dados numéricos
3.
BMC Med Genet ; 21(1): 149, 2020 07 16.
Artigo em Inglês | MEDLINE | ID: mdl-32677908

RESUMO

BACKGROUND: Short-chain enoyl-CoA hydratase deficiency (ECHS1D), also known as ECHS1 deficiency, is a rare inborn metabolic disorder with clinical presentations characterized by Leigh syndrome (LS). Thirty-four different pathogenic mutations have been identified from over 40 patients to date. CASE PRESENTATION: Here, we report five Chinese patients with clinical syndromes typified as LS. Despite different initial symptoms, all patients presented developmental regression, dystonia, common radiological features such as symmetrical bilateral brain abnormalities, and similar metabolic results such as elevated plasma lactate and 2,3-dihydroxy-2-methylbutyrate. Utilizing whole-exome sequencing (WES), we identified eight distinct variants in ECHS1, with six novel variants, and the remaining two variants have been previously reported. Interestingly, one of the six novel variants, c.463G > A (p.Gly155Ser), was detected in three patients from unrelated families, suggesting a potential founder effect already described for a few mutations in LS. Incorporating both genetic analysis and medical results, including magnetic resonance imaging (MRI), electroencephalography (EEG), and biochemical testing, our study enriched the mutation spectrum of the ECHS1 gene and confirmed the phenotypic presentations of LS. CONCLUSIONS: The severity of ECHS1 deficiency seems to vary. It was affected by both genetics and external environmental factors that lead to increased metabolism. Our study enriched the mutation spectrum of the ECHS1 gene, confirmed the phenotypic presentations, and highlighted the importance of the valine catabolic pathway in Leigh syndrome. Further studies are required to examine the potential founder mutation c.463G > A (p.Gly155Ser) and the role of ECHS1 in relevant pathways.


Assuntos
Grupo com Ancestrais do Continente Asiático/genética , Enoil-CoA Hidratase/genética , Doença de Leigh/genética , Mutação/genética , Sequenciamento Completo do Exoma , Sequência de Bases , Encéfalo/diagnóstico por imagem , Encéfalo/patologia , Criança , Pré-Escolar , Família , Feminino , Humanos , Lactente , Recém-Nascido , Imagem por Ressonância Magnética , Masculino , Linhagem
4.
Biochim Biophys Acta Bioenerg ; 1861(8): 148213, 2020 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-32335026

RESUMO

Mutations in NDUFS4, which encodes an accessory subunit of mitochondrial oxidative phosphorylation (OXPHOS) complex I (CI), induce Leigh syndrome (LS). LS is a poorly understood pediatric disorder featuring brain-specific anomalies and early death. To study the LS pathomechanism, we here compared OXPHOS proteomes between various Ndufs4-/- mouse tissues. Ndufs4-/- animals displayed significantly lower CI subunit levels in brain/diaphragm relative to other tissues (liver/heart/kidney/skeletal muscle), whereas other OXPHOS subunit levels were not reduced. Absence of NDUFS4 induced near complete absence of the NDUFA12 accessory subunit, a 50% reduction in other CI subunit levels, and an increase in specific CI assembly factors. Among the latter, NDUFAF2 was most highly increased. Regarding NDUFS4, NDUFA12 and NDUFAF2, identical results were obtained in Ndufs4-/- mouse embryonic fibroblasts (MEFs) and NDUFS4-mutated LS patient cells. Ndufs4-/- MEFs contained active CI in situ but blue-native-PAGE highlighted that NDUFAF2 attached to an inactive CI subcomplex (CI-830) and inactive assemblies of higher MW. In NDUFA12-mutated LS patient cells, NDUFA12 absence did not reduce NDUFS4 levels but triggered NDUFAF2 association to active CI. BN-PAGE revealed no such association in LS patient fibroblasts with mutations in other CI subunit-encoding genes where NDUFAF2 was attached to CI-830 (NDUFS1, NDUFV1 mutation) or not detected (NDUFS7 mutation). Supported by enzymological and CI in silico structural analysis, we conclude that absence of NDUFS4 induces near complete absence of NDUFA12 but not vice versa, and that NDUFAF2 stabilizes active CI in Ndufs4-/- mice and LS patient cells, perhaps in concert with mitochondrial inner membrane lipids.


Assuntos
Complexo I de Transporte de Elétrons/deficiência , Complexo I de Transporte de Elétrons/genética , Deleção de Genes , Doença de Leigh/genética , Proteínas Mitocondriais/metabolismo , Chaperonas Moleculares/metabolismo , NADPH Desidrogenase/metabolismo , Animais , Fibroblastos/metabolismo , Técnicas de Inativação de Genes , Humanos , Doença de Leigh/metabolismo , Camundongos , Fosforilação Oxidativa , Estabilidade Proteica
5.
Oncogene ; 39(19): 3879-3892, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32203162

RESUMO

Mutants in the gene encoding mitochondrion-associated protein LRPPRC were found to be associated with French Canadian Type Leigh syndrome, a human disorder characterized with neurodegeneration and cytochrome c oxidase deficiency. LRPPRC interacts with one of microtubule-associated protein family MAP1S that promotes autophagy initiation and maturation to suppress genomic instability and tumorigenesis. Previously, although various studies have attributed LRPPRC nuclear acid-associated functions, we characterized that LRPPRC acted as an inhibitor of autophagy in human cancer cells. Here we show that liver-specific deletion of LRPPRC causes liver-specific increases of YAP and P27 and decreases of P62, leading to an increase of cell polyploidy and an impairment of autophagy maturation. The blockade of autophagy maturation and promotion of polyploidy caused by LRPPRC depletion synergistically enhances diethylnitrosamine-induced DNA damage, genome instability, and further tumorigenesis so that LRPPRC knockout mice develop more and larger hepatocellular carcinomas and survive a shorter lifespan. Therefore, LRPPRC suppresses genome instability and hepatocellular carcinomas and promotes survivals in mice by sustaining Yap-P27-mediated cell ploidy and P62-HDAC6-controlled autophagy maturation.


Assuntos
Carcinoma Hepatocelular/genética , Deficiência de Citocromo-c Oxidase/genética , Desacetilase 6 de Histona/genética , Doença de Leigh/genética , Neoplasias Hepáticas/genética , Proteínas de Neoplasias/genética , Proteínas Adaptadoras de Transdução de Sinal/genética , Animais , Autofagia/genética , Canadá , Carcinogênese/genética , Carcinoma Hepatocelular/patologia , Deficiência de Citocromo-c Oxidase/patologia , Instabilidade Genômica/genética , Células HeLa , Humanos , Doença de Leigh/patologia , Fígado/metabolismo , Fígado/patologia , Neoplasias Hepáticas/patologia , Camundongos , Camundongos Knockout , Ploidias , Antígeno Nuclear de Célula em Proliferação/genética , Proteínas de Ligação a RNA/genética , Fatores de Transcrição/genética
6.
PLoS Genet ; 16(3): e1008604, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32130224

RESUMO

The influence of environmental insults on the onset and progression of mitochondrial diseases is unknown. To evaluate the effects of infection on mitochondrial disease we used a mouse model of Leigh Syndrome, where a missense mutation in the Taco1 gene results in the loss of the translation activator of cytochrome c oxidase subunit I (TACO1) protein. The mutation leads to an isolated complex IV deficiency that mimics the disease pathology observed in human patients with TACO1 mutations. We infected Taco1 mutant and wild-type mice with a murine cytomegalovirus and show that a common viral infection exacerbates the complex IV deficiency in a tissue-specific manner. We identified changes in neuromuscular morphology and tissue-specific regulation of the mammalian target of rapamycin pathway in response to viral infection. Taken together, we report for the first time that a common stress condition, such as viral infection, can exacerbate mitochondrial dysfunction in a genetic model of mitochondrial disease.


Assuntos
Deficiência de Citocromo-c Oxidase/genética , Infecções por Citomegalovirus/genética , Complexo IV da Cadeia de Transporte de Elétrons/genética , Doenças Mitocondriais/genética , Proteínas Mitocondriais/genética , Muromegalovirus/patogenicidade , Animais , Deficiência de Citocromo-c Oxidase/virologia , Infecções por Citomegalovirus/virologia , Modelos Animais de Doenças , Doença de Leigh/genética , Doença de Leigh/virologia , Camundongos , Camundongos Endogâmicos C57BL , Doenças Mitocondriais/virologia , Mutação/genética , Serina-Treonina Quinases TOR/genética
7.
Medicine (Baltimore) ; 99(5): e18634, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32000367

RESUMO

Leigh syndrome (also called Leigh disease or subacute necrotizing encephalomyelopathy) is a rare inherited neurometabolic disorder, which affects the central nervous system. This meta-study systematically analyzed clinical manifestations, respiratory chain enzyme complex deficiency, and gene mutations.Literature was searched for publications in MEDLINE, EMBASE, and the China National Knowledge Infrastructure database for meta-analyses of the incidence of clinical symptoms, laboratory assessments, imaging data, muscle biopsy histochemical staining, activity of the mitochondrial respiratory chain enzyme complex, gene mutations, and the association between age at disease onset and type of gene mutations.This study included 5 studies with 385 Leigh syndrome patients. The most common clinical features of Leigh syndrome included elevated blood and/or cerebrospinal fluid (CSF) levels of lactate (72%), developmental retardation (57%), hypotonia (42%), followed by respiratory dysfunction (34%), epileptic seizures (33%), poor feeding (29%), and weakness (27%). Approximately 80% of the patients had deficiencies of the respiratory chain enzyme complex or isolated complex I deficiency (35%), 32% had mitochondrial DNA (mtDNA) mutations, and 38% had nuclear DNA (nDNA) mutations. Patients with nDNA mutations were younger than those with mtDNA mutations (8.82 ± 13.88 vs 26.20 ±â€Š41.11 years, P = .007).The data from the current meta-analysis demonstrated a variety of clinical and molecular manifestations of Leigh syndrome, with upregulated lactate levels in the blood or CSF being the most common feature. Diagnosis of Leigh syndrome could be confirmed using combined enzymatic and genetic analyses.


Assuntos
Doença de Leigh/epidemiologia , Complexo I de Transporte de Elétrons/deficiência , Humanos , Doença de Leigh/enzimologia , Doença de Leigh/genética , Mutação
9.
BMC Pediatr ; 20(1): 41, 2020 01 29.
Artigo em Inglês | MEDLINE | ID: mdl-31996177

RESUMO

BACKGROUND: Maternally inherited complex I deficiencies due to mutations in MT-ND genes represent a heterogeneous group of multisystem mitochondrial disorders (MD) with a unfavourable prognosis. The aim of the study was to characterize the impact of the mutations in MT-ND genes, including the novel m.13091 T > C variant, on the course of the disease, and to analyse the activities of respiratory chain complexes, the amount of protein subunits, and the mitochondrial energy-generating system (MEGS) in available muscle biopsies and cultivated fibroblasts. METHODS: The respiratory chain complex activities were measured by spectrophotometry, MEGS were analysed using radiolabelled substrates, and protein amount by SDS-PAGE or BN-PAGE in muscle or fibroblasts. RESULTS: In our cohort of 106 unrelated families carrying different mtDNA mutations, we found heteroplasmic mutations in the genes MT-ND1, MT-ND3, and MT-ND5, including the novel variant m.13091 T > C, in 13 patients with MD from 12 families. First symptoms developed between early childhood and adolescence and progressed to multisystem disease with a phenotype of Leigh or MELAS syndromes. MRI revealed bilateral symmetrical involvement of deep grey matter typical of Leigh syndrome in 6 children, cortical/white matter stroke-like lesions suggesting MELAS syndrome in 3 patients, and a combination of cortico-subcortical lesions and grey matter involvement in 4 patients. MEGS indicated mitochondrial disturbances in all available muscle samples, as well as a significantly decreased oxidation of [1-14C] pyruvate in fibroblasts. Spectrophotometric analyses revealed a low activity of complex I and/or complex I + III in all muscle samples except one, but the activities in fibroblasts were mostly normal. No correlation was found between complex I activities and mtDNA mutation load, but higher levels of heteroplasmy were generally found in more severely affected patients. CONCLUSIONS: Maternally inherited complex I deficiencies were found in 11% of families with mitochondrial diseases in our region. Six patients manifested with Leigh, three with MELAS. The remaining four patients presented with an overlap between these two syndromes. MEGS, especially the oxidation of [1-14C] pyruvate in fibroblasts might serve as a sensitive indicator of functional impairment due to MT-ND mutations. Early onset of the disease and higher level of mtDNA heteroplasmy were associated with a worse prognosis.


Assuntos
DNA Mitocondrial , Complexo I de Transporte de Elétrons/deficiência , Doença de Leigh/genética , Síndrome MELAS/genética , Doenças Mitocondriais/genética , Mutação , Adolescente , Adulto , Idade de Início , Biópsia , Encéfalo/diagnóstico por imagem , Encéfalo/patologia , Células Cultivadas , Criança , Complexo I de Transporte de Elétrons/genética , Complexo I de Transporte de Elétrons/metabolismo , Feminino , Fibroblastos/metabolismo , Humanos , Lactente , Recém-Nascido , Imagem por Ressonância Magnética , Músculo Esquelético/metabolismo
10.
Brain Dev ; 42(1): 69-72, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31500933

RESUMO

BACKGROUND: The mitochondrial DNA MT-ATP6 gene encodes the ATP6 subunit of the mitochondrial ATP synthase. The m.9185 T > C variant in MT-ATP6 has been reported to cause various neurological disorders including late-onset Leigh syndrome (LS). To our knowledge, there has been no reported case of infantile-onset LS associated with the m.9185 T > C variant. Herein, we report a patient with early-onset LS complicated with infantile spasms who exhibited profound developmental delay. CASE REPORT: A 3-month-old Japanese girl presented with focal seizures. Brain magnetic resonance imaging (MRI) revealed bilateral lesions in the basal ganglia and cerebral peduncle. Laboratory evaluation demonstrated marked elevations of lactate and pyruvate in both venous blood and cerebrospinal fluid. At 6 months, she developed infantile spasms, which were ceased by adrenocorticotropic hormone therapy. At 2 years of age, she was bedridden due to hypotonic quadriplegia and was unable to make eye contact. Whole-exome sequencing identified apparently de novo homoplasmic m.9185 T > C variant in her blood. CONCLUSION: This is the first case report describing early infantile-onset LS associated with the m.9185 T > C variant, and thereby broadens the phenotypic spectrum of m.9185 T > C-related disorders.


Assuntos
Doença de Leigh/genética , ATPases Mitocondriais Próton-Translocadoras/genética , Espasmos Infantis/genética , Feminino , Humanos , Lactente , Mutação
11.
Int J Dev Biol ; 63(8-9-10): 497-508, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31840787

RESUMO

The unicellular slime mould Dictyostelium discoideum is a valuable eukaryotic model organism in the study of mitochondrial biology and disease. As a member of the Amoebozoa, a sister clade to the animals and fungi, Dictyostelium mitochondrial biology shares commonalities with these organisms, but also exhibits some features of plants. As such it has made significant contributions to the study of eukaryotic mitochondrial biology. This review provides an overview of the advances in mitochondrial biology made by the study of Dictyostelium and examines several examples where Dictyostelium has and will contribute to the understanding of mitochondrial disease. The study of Dictyostelium's mitochondrial biology has contributed to the understanding of mitochondrial genetics, transcription, protein import, respiration, morphology and trafficking, and the role of mitochondria in cellular differentiation. Dictyostelium is also proving to be a versatile model organism in the study both of classical mitochondrial disease e.g. Leigh syndrome, and in mitochondria-associated neurodegenerative diseases like Parkinson's disease. The study of mitochondrial diseases presents a unique challenge due to the cryptic nature of their genotype-phenotype relationship. The use of Dictyostelium can contribute to resolving this problem by providing a genetically tractable, haploid eukaryotic organism with a suite of readily characterised phenotype readouts of cellular signalling pathways. Dictyostelium has provided insight into the signalling pathways involved in multiple neurodegenerative diseases and will continue to provide a significant contribution to the understanding of mitochondrial biology and disease.


Assuntos
Dictyostelium/fisiologia , Mitocôndrias/genética , Doenças Mitocondriais/genética , Animais , Diferenciação Celular , Movimento Celular , Dictyostelium/genética , Genoma Mitocondrial , Serina Peptidase 2 de Requerimento de Alta Temperatura A/genética , Humanos , Doença de Leigh/genética , Modelos Genéticos , Doenças Neurodegenerativas/genética , Oxirredutases/metabolismo , Doença de Parkinson/genética , Fenótipo , Transdução de Sinais , Transcrição Genética
15.
PLoS One ; 14(9): e0221829, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31479473

RESUMO

Mitochondrial DNA (mtDNA) genome integrity is essential for proper mitochondrial respiratory chain function to generate cellular energy. Nuclear genes encode several proteins that function at the mtDNA replication fork, including mitochondrial single-stranded DNA-binding protein (SSBP1), which is a tetrameric protein that binds and protects single-stranded mtDNA (ssDNA). Recently, two studies have reported pathogenic variants in SSBP1 associated with hearing loss, optic atrophy, and retinal degeneration. Here, we report a 14-year-old Chinese boy with severe and progressive mitochondrial disease manifestations across the full Pearson, Kearns-Sayre, and Leigh syndromes spectrum, including infantile anemia and bone marrow failure, growth failure, ptosis, ophthalmoplegia, ataxia, severe retinal dystrophy of the rod-cone type, sensorineural hearing loss, chronic kidney disease, multiple endocrine deficiencies, and metabolic strokes. mtDNA genome sequencing identified a single large-scale 5 kilobase mtDNA deletion (m.8629_14068del5440), present at 68% and 16% heteroplasmy in the proband's fibroblast cell line and blood, respectively, suggestive of a mtDNA maintenance defect. On trio whole exome blood sequencing, the proband was found to harbor a novel de novo heterozygous mutation c.79G>A (p.E27K) in SSBP1. Size exclusion chromatography of p.E27K SSBP1 revealed it remains a stable tetramer. However, differential scanning fluorimetry demonstrated p.E27K SSBP1 relative to wild type had modestly decreased thermostability. Functional assays also revealed p.E27K SSBP1 had altered DNA binding. Molecular modeling of SSBP1 tetramers with varying combinations of mutant subunits predicted general changes in surface accessible charges, strength of inter-subunit interactions, and protein dynamics. Overall, the observed changes in protein dynamics and DNA binding behavior suggest that p.E27K SSBP1 can interfere with DNA replication and precipitate the introduction of large-scale mtDNA deletions. Thus, a single large-scale mtDNA deletion (SLSMD) with manifestations across the clinical spectrum of Pearson, Kearns-Sayre, and Leigh syndromes may result from a nuclear gene disorder disrupting mitochondrial DNA replication.


Assuntos
Acil-CoA Desidrogenase de Cadeia Longa/deficiência , Síndrome Congênita de Insuficiência da Medula Óssea/genética , DNA Mitocondrial/genética , Proteínas de Ligação a DNA/genética , Síndrome de Kearns-Sayre/genética , Doença de Leigh/genética , Erros Inatos do Metabolismo Lipídico/genética , Doenças Mitocondriais/genética , Proteínas Mitocondriais/genética , Doenças Musculares/genética , Mutação , Acil-CoA Desidrogenase de Cadeia Longa/genética , Adolescente , Sequência de Aminoácidos , Linhagem Celular , Criança , Síndrome Congênita de Insuficiência da Medula Óssea/complicações , Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/metabolismo , Heterozigoto , Humanos , Síndrome de Kearns-Sayre/complicações , Doença de Leigh/complicações , Erros Inatos do Metabolismo Lipídico/complicações , Masculino , Doenças Mitocondriais/complicações , Proteínas Mitocondriais/química , Proteínas Mitocondriais/metabolismo , Simulação de Dinâmica Molecular , Doenças Musculares/complicações , Fenótipo , Estabilidade Proteica , Estrutura Quaternária de Proteína , Deleção de Sequência , Sequenciamento Completo do Exoma
16.
Mol Genet Genomic Med ; 7(10): e00945, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31454184

RESUMO

BACKGROUND: Uniparental disomy (UPD) leading to autosomal recessive (AR) diseases is rare. We found an unusual homozygous state in two nonconsanguineous families, and only one parent in each family was a heterozygote. METHODS: Two patients with homozygosity for pathogenic variants were revealed by whole-exome sequencing (WES), further Sanger sequencing found that only one of the parents was a heterozygote. Initial genotype and copy number variations analysis from WES data of probands involving whole chromosomes 1 and 9 containing these two pathogenic variants were performed, genome-wide single-nucleotide polymorphism (SNP) array analysis was used to confirm these results. RESULTS: Whole-exome sequencing identified a homozygous c.3423_3424delTG mutation in AGL in patient 1 and a homozygous c.241-1G>C mutation in SURF1 in patient 2. Further parental testing found that only the two patients' healthy fathers were heterozygous. WES-based copy number and genotype analysis found a copy-neutral loss of heterozygosity (LOH) of whole chromosome 1 in patient 1 and of whole chromosomes 9 and 10 in patient 2. Further genome-wide SNP array and family haplotype analyses confirmed whole paternal uniparental isodisomy (UPiD) 1 in patient 1 and paternal UPiD 9 and maternal UPiD 10 in patient 2. Therefore, UPiD caused AR monogenic glycogen storage disease type-III (GSDIII) in patient 1 and Leigh syndrome in patient 2 through non-Mendelian inheritance of two mutant copies of a gene from each patient's father. CONCLUSION: Our report highlights that a single NGS-based analysis could allow us to find homozygous sequence variants and copy-neutral LOH in such cases. Our report also describes the first case of GSDIII caused by UPiD 1 and Leigh syndrome caused by UPiD 9.


Assuntos
Doença de Depósito de Glicogênio Tipo III/diagnóstico , Doença de Leigh/diagnóstico , Perda de Heterozigosidade , Dissomia Uniparental/genética , Deleção de Genes , Frequência do Gene , Sistema da Enzima Desramificadora do Glicogênio/genética , Doença de Depósito de Glicogênio Tipo III/genética , Homozigoto , Humanos , Lactente , Doença de Leigh/genética , Masculino , Proteínas de Membrana/genética , Proteínas Mitocondriais/genética , Linhagem , Polimorfismo de Nucleotídeo Único , Sequenciamento Completo do Exoma
17.
JCI Insight ; 4(14)2019 07 25.
Artigo em Inglês | MEDLINE | ID: mdl-31341105

RESUMO

Mitochondrial dysfunction characterizes many rare and common age-associated diseases. The biochemical consequences, underlying clinical manifestations, and potential therapeutic targets, remain to be better understood. We tested the hypothesis that lipid dyshomeostasis in mitochondrial disorders goes beyond mitochondrial fatty acid ß-oxidation, particularly in liver. This was achieved using comprehensive untargeted and targeted lipidomics in a case-control cohort of patients with Leigh syndrome French-Canadian variant (LSFC), a mitochondrial disease caused by mutations in LRPPRC, and in mice harboring liver-specific inactivation of Lrpprc (H-Lrpprc-/-). We discovered a plasma lipid signature discriminating LSFC patients from controls encompassing lower levels of plasmalogens and conjugated bile acids, which suggest perturbations in peroxisomal lipid metabolism. This premise was reinforced in H-Lrpprc-/- mice, which compared with littermates recapitulated a similar, albeit stronger peroxisomal metabolic signature in plasma and liver including elevated levels of very-long-chain acylcarnitines. These mice also presented higher transcript levels for hepatic markers of peroxisome proliferation in addition to lipid remodeling reminiscent of nonalcoholic fatty liver diseases. Our study underscores the value of lipidomics to unveil unexpected mechanisms underlying lipid dyshomeostasis ensuing from mitochondrial dysfunction herein implying peroxisomes and liver, which likely contribute to the pathophysiology of LSFC, but also other rare and common mitochondrial diseases.


Assuntos
Doença de Leigh/diagnóstico , Metabolismo dos Lipídeos/genética , Proteínas de Neoplasias/genética , Plasmalogênios/sangue , Adolescente , Animais , Ácidos e Sais Biliares/metabolismo , Biomarcadores/sangue , Biomarcadores/metabolismo , Carnitina/análogos & derivados , Carnitina/sangue , Carnitina/metabolismo , Estudos de Casos e Controles , Modelos Animais de Doenças , Feminino , Humanos , Doença de Leigh/sangue , Doença de Leigh/genética , Doença de Leigh/metabolismo , Lipidômica , Fígado/metabolismo , Masculino , Camundongos , Camundongos Knockout , Mitocôndrias/metabolismo , Mutação , Proteínas de Neoplasias/metabolismo , Peroxissomos/metabolismo , Plasmalogênios/metabolismo , Estudos Prospectivos , Adulto Jovem
18.
J Neurol Sci ; 404: 91-100, 2019 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-31352295

RESUMO

In our previously published study, we cared for 165 thiamine deficient Leigh syndrome (LS) patients who presented in acute life threatening conditions with severe neurological abnormalities. However the molecular basis for this atypical phenotype was not explored. This study is an effort to undermine the possible molecular defects in mitochondria of those patients and put-forth an explanation towards this clinical presentation. Protein coding genes of mitochondrial (mt) DNA were sequenced in total 165 LS patients and 94 age matched controls. To understand their pathogenic significance, nucleotide variations were also studied using various in-silico tools. Histochemical and electron microscopic analysis was also done in tissue samples obtained from 23 patients. We observed a very high level of genetic heterogeneity across the mt DNA of all these patients. In the concordance of published literature we also observed a large number of variations in ND5 gene (hot spot for LS). We also observed a total 13 nucleotide variations across COX genes, which is otherwise not common in LS. As per in-silico analysis, many of these variations were suggested to be pathogenic. Histochemical and electron microscopic studies also suggested the defects in the mitochondria of these patients. As these patients were thiamine deficient, hence we propose that genetic defects and thiamine deficiency may together severely affect the ATP levelof these patients, leading to acute and life threatening clinical presentation. Present study has opened up many avenues for further research towards understanding the genetic basis and possible role of thiamine deficiency in LS patients.


Assuntos
Heterogeneidade Genética , Genoma Mitocondrial , Doença de Leigh/genética , Deficiência de Tiamina/genética , Biópsia , Criança , DNA Mitocondrial/genética , Humanos , Doença de Leigh/complicações , Doença de Leigh/patologia , Mitocôndrias Musculares/metabolismo , Mitocôndrias Musculares/patologia , Músculo Esquelético/metabolismo , Músculo Esquelético/patologia , Deficiência de Tiamina/complicações , Deficiência de Tiamina/patologia
19.
Hum Mol Genet ; 28(19): 3163-3174, 2019 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-31261379

RESUMO

Disease-associated variants in mitochondrial DNA (mtDNA) are frequently heteroplasmic, a state of co-existence with the wild-type genome. Because heteroplasmy correlates with the severity and penetrance of disease, improvement in the ratio between these genomes in favor of the wild-type, known as heteroplasmy shifting, is potentially therapeutic. We evaluated known pathogenic mtDNA variants and identified those with the potential for allele-specific differences in the formation of non-Watson-Crick G-quadruplex (GQ) structures. We found that the Leigh syndrome (LS)-associated m.10191C variant promotes GQ formation within local sequence in vitro. Interaction of this sequence with a small molecule GQ-binding agent, berberine hydrochloride, further increased GQ stability. The GQ formed at m.10191C differentially impeded the processivity of the mitochondrial DNA polymerase gamma (Pol γ) in vitro, providing a potential means to favor replication of the wild-type allele. We tested the potential for shifting heteroplasmy through the cyclical application of two different mitochondria-targeted GQ binding compounds in primary fibroblasts from patients with m.10191T>C heteroplasmy. Treatment induced alternating mtDNA depletion and repopulation and was effective in shifting heteroplasmy towards the non-pathogenic allele. Similar treatment of pathogenic heteroplasmies that do not affect GQ formation did not induce heteroplasmy shift. Following treatment, heteroplasmic m.10191T>C cells had persistent improvements and heteroplasmy and a corresponding increase in maximal mitochondrial oxygen consumption. This study demonstrates the potential for using small-molecule GQ-binding agents to induce genetic and functional improvements in m.10191T>C heteroplasmy.


Assuntos
Alcaloides de Berberina/farmacologia , DNA Mitocondrial/genética , Doença de Leigh/genética , Berberina/química , Alcaloides de Berberina/química , Células Cultivadas , Polimerase do DNA Mitocondrial/metabolismo , DNA Mitocondrial/química , DNA Mitocondrial/efeitos dos fármacos , Fibroblastos/citologia , Fibroblastos/efeitos dos fármacos , Quadruplex G/efeitos dos fármacos , Variação Genética , Humanos , Doença de Leigh/metabolismo
20.
BMJ Case Rep ; 12(7)2019 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-31308188

RESUMO

A term girl infant delivered following foetal distress presented with early respiratory distress syndrome and lactic acidaemia. She subsequently underwent detailed investigation for primary lactic acidaemia and was identified as homozygous for the c.515A>G,p.(Tyr172Cys) missense variant in the LRPPRC gene. Variants in this gene are known to cause French-Canadian type Leigh syndrome. Both parents were confirmed to be heterozygous for this mutation. This is the first case report of mitochondrial respiratory chain complex IV deficiency presenting as foetal distress and neonatal respiratory distress syndrome.


Assuntos
Deficiência de Citocromo-c Oxidase/complicações , Síndrome do Desconforto Respiratório do Recém-Nascido/etiologia , Acidose Láctica/etiologia , Consanguinidade , Deficiência de Citocromo-c Oxidase/genética , Evolução Fatal , Feminino , Homozigoto , Humanos , Recém-Nascido , Doença de Leigh/genética , Mutação/genética , Proteínas de Neoplasias/genética , Doenças Raras
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