RESUMEN
Inherited deficiency of thymidine phosphorylase (TP), encoded by TYMP, leads to a rare disease with multiple mitochondrial DNA (mtDNA) abnormalities, mitochondrial neurogastrointestinal encephalomyopathy (MNGIE). However, the impact of TP deficiency on lysosomes remains unclear, which are important for mitochondrial quality control and nucleic acid metabolism. Muscle biopsy tissue and skin fibroblasts from MNGIE patients, patients with m.3243 A > G mitochondrial encephalopathy, lactic acidosis and stroke-like episodes (MELAS) and healthy controls (HC) were collected to perform mitochondrial and lysosomal functional analyses. In addition to mtDNA abnormalities, compared to controls distinctively reduced expression of LAMP1 and increased mitochondrial content were detected in the muscle tissue of MNGIE patients. Skin fibroblasts from MNGIE patients showed decreased expression of LAMP2, lowered lysosomal acidity, reduced enzyme activity and impaired protein degradation ability. TYMP knockout or TP inhibition in cells can also induce the similar lysosomal dysfunction. Using lysosome immunoprecipitation (Lyso- IP), increased mitochondrial proteins, decreased vesicular proteins and V-ATPase enzymes, and accumulation of various nucleosides were detected in lysosomes with TP deficiency. Treatment of cells with high concentrations of dThd and dUrd also triggers lysosomal dysfunction and disruption of mitochondrial homeostasis. Therefore, the results provided evidence that TP deficiency leads to nucleoside accumulation in lysosomes and lysosomal dysfunction, revealing the widespread disruption of organelles underlying MNGIE.
Asunto(s)
ADN Mitocondrial , Fibroblastos , Lisosomas , Mitocondrias , Encefalomiopatías Mitocondriales , Nucleósidos , Timidina Fosforilasa , Humanos , Lisosomas/metabolismo , Timidina Fosforilasa/metabolismo , Timidina Fosforilasa/deficiencia , Timidina Fosforilasa/genética , Encefalomiopatías Mitocondriales/metabolismo , Encefalomiopatías Mitocondriales/patología , Encefalomiopatías Mitocondriales/genética , Fibroblastos/metabolismo , Fibroblastos/patología , ADN Mitocondrial/genética , ADN Mitocondrial/metabolismo , Mitocondrias/metabolismo , Nucleósidos/metabolismo , Seudoobstrucción Intestinal/metabolismo , Seudoobstrucción Intestinal/patología , Seudoobstrucción Intestinal/enzimología , Seudoobstrucción Intestinal/genética , Oftalmoplejía/metabolismo , Oftalmoplejía/patología , Oftalmoplejía/congénito , Distrofia Muscular Oculofaríngea/metabolismo , Distrofia Muscular Oculofaríngea/patología , Masculino , Femenino , Piel/patología , Piel/metabolismo , Proteína 2 de la Membrana Asociada a los Lisosomas/metabolismoRESUMEN
Encephalomyopathic mitochondrial DNA (mtDNA) depletion syndrome 13 (MTDPS13) is an autosomal recessive disorder arising from biallelic F-box and leucine-rich repeat (LRR) protein 4 (FBXL4) gene mutations. Recent advances have shown that excessive BCL2 interacting protein 3 (BNIP3)/ BCL2 interacting protein 3 like (BNIP3L)-dependent mitophagy underlies the molecular pathogenesis of MTDPS13. Here, we provide an overview of these groundbreaking findings and discuss potential therapeutic strategies for this fatal disease.
Asunto(s)
Encefalomiopatías Mitocondriales , Mitofagia , Humanos , Mitofagia/genética , Mitocondrias/metabolismo , ADN Mitocondrial/genética , Mutación , Encefalomiopatías Mitocondriales/genética , Encefalomiopatías Mitocondriales/metabolismo , Encefalomiopatías Mitocondriales/patología , Proteínas Proto-Oncogénicas c-bcl-2/metabolismo , Proteínas Mitocondriales/genética , Proteínas Mitocondriales/metabolismo , Proteínas de la Membrana/genética , Proteínas de la Membrana/metabolismo , Proteínas Proto-Oncogénicas/genética , Proteínas Supresoras de Tumor/genética , Proteínas Supresoras de Tumor/metabolismoRESUMEN
Biallelic pathogenic variants in subunits of succinyl-CoA synthetase (SCS), a tricarboxylic acid (TCA) cycle enzyme, are associated with mitochondrial encephalomyopathy in humans. SCS catalyzes the interconversion of succinyl-CoA to succinate, coupled to substrate-level phosphorylation of either ADP or GDP, within the TCA cycle. SCS-deficient encephalomyopathy typically presents in infancy and early childhood, with many patients succumbing to the disease during childhood. Common symptoms include abnormal brain MRI, basal ganglia lesions and cerebral atrophy, severe hypotonia, dystonia, progressive psychomotor regression, and growth deficits. Although subunits of SCS were first identified as causal genes for progressive metabolic encephalomyopathy in the early 2000s, recent investigations are now beginning to unravel the pathomechanisms underlying this metabolic disorder. This article reviews the current understanding of SCS function within and outside the TCA cycle as it relates to the complex and multifactorial mechanisms underlying SCS-related mitochondrial encephalomyopathy.
Asunto(s)
Encefalomiopatías Mitocondriales , Succinato-CoA Ligasas , Preescolar , Humanos , Encefalomiopatías Mitocondriales/genética , Encefalomiopatías Mitocondriales/metabolismo , Mitocondrias/metabolismo , Succinato-CoA Ligasas/genética , Succinato-CoA Ligasas/metabolismo , Estrés OxidativoRESUMEN
Mitochondrial encephalomyopathies (ME) are frequently associated with mutations of mitochondrial DNA, but the pathogenesis of a subset of ME (sME) remains elusive. Here we report that haploinsufficiency of a mitochondrial inner membrane protein, Mic60, causes progressive neurological abnormalities with insulted mitochondrial structure and neuronal loss in mice. In addition, haploinsufficiency of Mic60 reduces mitochondrial membrane potential and cellular ATP production, increases reactive oxygen species, and alters mitochondrial oxidative phosphorylation complexes in neurons in an age-dependent manner. Moreover, haploinsufficiency of Mic60 compromises brain glucose intake and oxygen consumption in mice, resembling human ME syndrome. We further discover that MIC60 protein expression declined significantly in human sME, implying that insufficient MIC60 may contribute for pathogenesis of human ME. Notably, systemic administration of antioxidant N-acetylcysteine largely reverses mitochondrial dysfunctions and metabolic disorders in haplo-insufficient Mic60 mice, also restores neurological abnormal symptom. These results reveal Mic60 is required in the maintenance of mitochondrial integrity and function, and likely a potential therapeutics target for mitochondrial encephalomyopathies.
Asunto(s)
Encefalomiopatías Mitocondriales , Animales , Ratones , Humanos , Encefalomiopatías Mitocondriales/genética , Encefalomiopatías Mitocondriales/metabolismo , Proteínas Mitocondriales/metabolismo , Mitocondrias/metabolismo , ADN Mitocondrial , AntioxidantesRESUMEN
Primary mitochondrial diseases are a group of genetically and clinically heterogeneous disorders resulting from oxidative phosphorylation (OXPHOS) defects. COX11 encodes a copper chaperone that participates in the assembly of complex IV and has not been previously linked to human disease. In a previous study, we identified that COX11 knockdown decreased cellular adenosine triphosphate (ATP) derived from respiration, and that ATP levels could be restored with coenzyme Q10 (CoQ10 ) supplementation. This finding is surprising since COX11 has no known role in CoQ10 biosynthesis. Here, we report a novel gene-disease association by identifying biallelic pathogenic variants in COX11 associated with infantile-onset mitochondrial encephalopathies in two unrelated families using trio genome and exome sequencing. Functional studies showed that mutant COX11 fibroblasts had decreased ATP levels which could be rescued by CoQ10 . These results not only suggest that COX11 variants cause defects in energy production but reveal a potential metabolic therapeutic strategy for patients with COX11 variants.
Asunto(s)
Enfermedades Mitocondriales , Encefalomiopatías Mitocondriales , Humanos , Encefalomiopatías Mitocondriales/genética , Encefalomiopatías Mitocondriales/metabolismo , Enfermedades Mitocondriales/genética , Enfermedades Mitocondriales/metabolismo , Mitocondrias/metabolismo , Adenosina Trifosfato/metabolismo , Proteínas Transportadoras de Cobre/metabolismo , Proteínas Mitocondriales/genética , Proteínas Mitocondriales/metabolismo , Proteínas del Complejo de Cadena de Transporte de Electrón/metabolismoRESUMEN
Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) is often caused by an adenine to guanine variant at m.3243 (m.3243A>G) of the MT-TL1 gene. To understand how this pathogenic variant affects the nervous system, we differentiated human induced pluripotent stem cells (iPSCs) into excitatory neurons with normal (low heteroplasmy) and impaired (high heteroplasmy) mitochondrial function from MELAS patients with the m.3243A>G pathogenic variant. We combined micro-electrode array (MEA) measurements with RNA sequencing (MEA-seq) and found reduced expression of genes involved in mitochondrial respiration and presynaptic function, as well as non-cell autonomous processes in co-cultured astrocytes. Finally, we show that the clinical phase II drug sonlicromanol can improve neuronal network activity when treatment is initiated early in development. This was intricately linked with changes in the neuronal transcriptome. Overall, we provide insight in transcriptomic changes in iPSC-derived neurons with high m.3243A>G heteroplasmy, and show the pathology is partially reversible by sonlicromanol.
Asunto(s)
Diferenciación Celular/efectos de los fármacos , Diferenciación Celular/genética , Cromanos/farmacología , Heteroplasmia/genética , Células Madre Pluripotentes Inducidas/metabolismo , Neuronas/metabolismo , ARN de Transferencia de Leucina/genética , Transcriptoma , Animales , Astrocitos/metabolismo , Técnicas de Cultivo de Célula , Células Cultivadas , ADN Mitocondrial/genética , ADN Mitocondrial/metabolismo , Modelos Animales de Enfermedad , Perfilación de la Expresión Génica , Regulación de la Expresión Génica/efectos de los fármacos , Predisposición Genética a la Enfermedad , Humanos , Células Madre Pluripotentes Inducidas/citología , Encefalomiopatías Mitocondriales/diagnóstico , Encefalomiopatías Mitocondriales/etiología , Encefalomiopatías Mitocondriales/metabolismo , Neuronas/citología , Fenotipo , RatasRESUMEN
Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is a rare autosomal recessive disease caused by thymidine phosphorylase (TP) enzyme defect. As gastrointestinal changes do not revert in patients undergone TP replacement therapy, one can postulate that other unexplored mechanisms contribute to MNGIE pathophysiology. Hence, we focused on the local TP angiogenic potential that has never been considered in MNGIE. In this study, we investigated the enteric submucosal microvasculature and the effect of hypoxia on fibrosis and enteric neurons density in jejunal full-thickness biopsies collected from patients with MNGIE. Orcein staining was used to count blood vessels based on their size. Fibrosis was assessed using the Sirius Red and Fast Green method. Hypoxia and neoangiogenesis were determined via hypoxia-inducible-factor-1α (HIF-1α) and vascular endothelial cell growth factor (VEGF) protein expression, respectively. Neuron-specific enolase was used to label enteric neurons. Compared with controls, patients with MNGIE showed a decreased area of vascular tissue, but a twofold increase of submucosal vessels/mm2 with increased small size and decreased medium and large size vessels. VEGF positive vessels, fibrosis index, and HIF-1α protein expression were increased, whereas there was a diminished thickness of the longitudinal muscle layer with an increased interganglionic distance and reduced number of myenteric neurons. We demonstrated the occurrence of an angiopathy in the GI tract of patients with MNGIE. Neoangiogenetic changes, as detected by the abundance of small size vessels in the jejunal submucosa, along with hypoxia provide a morphological basis to explain neuromuscular alterations, vasculature breakdown, and ischemic abnormalities in MNGIE.NEW & NOTEWORTHY Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is characterized by a genetically driven defect of thymidine phosphorylase, a multitask enzyme playing a role also in angiogenesis. Indeed, major gastrointestinal bleedings are life-threatening complications of MNGIE. Thus, we focused on jejunal submucosal vasculature and showed intestinal microangiopathy as a novel feature occurring in this disease. Notably, vascular changes were associated with neuromuscular abnormalities, which may explain gut dysfunction and help to develop future therapeutic approaches in MNGIE.
Asunto(s)
Tracto Gastrointestinal/metabolismo , Seudoobstrucción Intestinal/metabolismo , Encefalomiopatías Mitocondriales/metabolismo , Distrofia Muscular Oculofaríngea/metabolismo , Neovascularización Patológica/metabolismo , Oftalmoplejía/congénito , Tracto Gastrointestinal/patología , Humanos , Seudoobstrucción Intestinal/patología , Encefalomiopatías Mitocondriales/patología , Distrofia Muscular Oculofaríngea/patología , Neovascularización Patológica/patología , Oftalmoplejía/metabolismo , Oftalmoplejía/patología , Timidina Fosforilasa/metabolismoRESUMEN
Mitochondrial encephalomyopathies are disorders caused by mitochondrial and nuclear DNA mutations which affect the nervous and muscular systems. Current therapies for mitochondrial encephalomyopathies are inadequate and mostly palliative. However, stem cell-derived mitochondria transplantation has been demonstrated to play an key part in metabolic rescue, which offers great promise for mitochondrial encephalomyopathies. Here, we summarize the present status of stem cell therapy for mitochondrial encephalomyopathy and discuss mitochondrial transfer routes and the protection mechanisms of stem cells. We also identify and summarize future perspectives and challenges for the treatment of these intractable disorders based on the concept of mitochondrial transfer from stem cells.
Asunto(s)
Mitocondrias/trasplante , Encefalomiopatías Mitocondriales/terapia , Trasplante de Células Madre/métodos , Animales , ADN Mitocondrial/inmunología , ADN Mitocondrial/metabolismo , Vesículas Extracelulares/inmunología , Vesículas Extracelulares/metabolismo , Humanos , Mitocondrias/inmunología , Mitocondrias/metabolismo , Encefalomiopatías Mitocondriales/inmunología , Encefalomiopatías Mitocondriales/metabolismo , Nanotubos , Células Madre/inmunología , Células Madre/metabolismoRESUMEN
Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is a rare autosomal recessive disease caused by TYMP mutations and thymidine phosphorylase (TP) deficiency. Thymidine and deoxyuridine accumulate impairing the mitochondrial DNA maintenance and integrity. Clinically, patients show severe and progressive gastrointestinal and neurological manifestations. The onset typically occurs in the second decade of life and mean age at death is 37 years. Signs and symptoms of MNGIE are heterogeneous and confirmatory diagnostic tests are not routinely performed by most laboratories, accounting for common misdiagnosis. Factors predictive of progression and appropriate tests for monitoring are still undefined. Several treatment options showed promising results in restoring the biochemical imbalance of MNGIE. The lack of controlled studies with appropriate follow-up accounts for the limited evidence informing diagnostic and therapeutic choices. The International Consensus Conference (ICC) on MNGIE, held in Bologna, Italy, on 30 March to 31 March 2019, aimed at an evidence-based consensus on diagnosis, prognosis, and treatment of MNGIE among experts, patients, caregivers and other stakeholders involved in caring the condition. The conference was conducted according to the National Institute of Health Consensus Conference methodology. A consensus development panel formulated a set of statements and proposed a research agenda. Specifically, the ICC produced recommendations on: (a) diagnostic pathway; (b) prognosis and the main predictors of disease progression; (c) efficacy and safety of treatments; and (f) research priorities on diagnosis, prognosis, and treatment. The Bologna ICC on diagnosis, management and treatment of MNGIE provided evidence-based guidance for clinicians incorporating patients' values and preferences.
Asunto(s)
Enfermedades Gastrointestinales/diagnóstico , Enfermedades Gastrointestinales/terapia , Encefalomiopatías Mitocondriales/diagnóstico , Encefalomiopatías Mitocondriales/terapia , Consenso , ADN Mitocondrial/genética , Enfermedades Gastrointestinales/genética , Enfermedades Gastrointestinales/metabolismo , Humanos , Cooperación Internacional , Encefalomiopatías Mitocondriales/genética , Encefalomiopatías Mitocondriales/metabolismo , Mutación , Timidina Fosforilasa/genética , Timidina Fosforilasa/metabolismoRESUMEN
Complex I (also known as NADH-ubiquinone oxidoreductase) deficiency is the most frequent mitochondrial disorder present in childhood. NADH-ubiquinone oxidoreductase iron-sulfur protein 3 (NDUFS3) is a catalytic subunit of the mitochondrial complex I; NDUFS3 is conserved from bacteria and essential for complex I function. Mutations affecting complex I, including in the Ndufs3 gene, cause fatal neurodegenerative diseases, such as Leigh syndrome. No treatment is available for these conditions. We developed and performed a detailed molecular characterization of a neuron-specific Ndufs3 conditional KO mouse model. We showed that deletion of Ndufs3 in forebrain neurons reduced complex I activity, altered brain energy metabolism, and increased locomotor activity with impaired motor coordination, balance, and stereotyped behavior. Metabolomics analyses showed an increase of glycolysis intermediates, suggesting an adaptive response to the complex I defect. Administration of metformin to these mice delayed the onset of the neurological symptoms but not of neuronal loss. This improvement was likely related to enhancement of glucose uptake and utilization, which are known effects of metformin in the brain. Despite reports that metformin inhibits complex I activity, our findings did not show worsening a complex I defect nor increases in lactic acid, suggesting that metformin should be further evaluated for use in patients with mitochondrial encephalopathies.
Asunto(s)
Complejo I de Transporte de Electrón/deficiencia , Metformina/farmacología , Enfermedades Mitocondriales/complicaciones , Encefalomiopatías Mitocondriales/tratamiento farmacológico , NADH Deshidrogenasa/fisiología , Neuronas/efectos de los fármacos , Animales , Metabolismo Energético , Femenino , Glucólisis , Hipoglucemiantes/farmacología , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Encefalomiopatías Mitocondriales/etiología , Encefalomiopatías Mitocondriales/metabolismo , Encefalomiopatías Mitocondriales/patología , Neuronas/metabolismo , Neuronas/patologíaRESUMEN
Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is an inherited disease caused by a deficiency in thymidine phosphorylase and characterized by elevated systemic deoxyribonucleotides and gastrointestinal (GI) and neurological manifestations. We report the clinical and biochemical manifestations that were evaluated in a single patient before, during, and after pregnancy, over a period of 7 years. GI symptoms significantly improved, and plasma deoxyribonucleotide concentrations decreased during pregnancy. Within days after delivery, the patient's digestive symptoms recurred, coinciding with a rapid increase in plasma deoxyribonucleotide concentrations. We hypothesize that the clinico-metabolic improvements could be attributed to the enzyme replacement action of the placental thymidine phosphorylase.
Asunto(s)
Progresión de la Enfermedad , Enfermedades Gastrointestinales , Encefalomiopatías Mitocondriales , Complicaciones del Embarazo , Actividades Cotidianas , Adulto , Femenino , Enfermedades Gastrointestinales/metabolismo , Enfermedades Gastrointestinales/fisiopatología , Humanos , Encefalomiopatías Mitocondriales/metabolismo , Encefalomiopatías Mitocondriales/fisiopatología , Embarazo , Complicaciones del Embarazo/metabolismo , Complicaciones del Embarazo/fisiopatología , Calidad de Vida , Adulto JovenRESUMEN
Mitochondria are best known for their role in energy production, and they are the only mammalian organelles that contain their own genomes. The mitochondrial genome mutation rate is reported to be 10-17 times higher compared to nuclear genomes as a result of oxidative damage caused by reactive oxygen species during oxidative phosphorylation. Pathogenic mitochondrial DNA mutations result in mitochondrial DNA disorders, which are among the most common inherited human diseases. Interventions of mitochondrial DNA disorders involve either the transfer of viable isolated mitochondria to recipient cells or genetically modifying the mitochondrial genome to improve therapeutic outcome. This review outlines the common mitochondrial DNA disorders and the key advances in the past decade necessary to improve the current knowledge on mitochondrial disease intervention. Although it is now 31 years since the first description of patients with pathogenic mitochondrial DNA was reported, the treatment for mitochondrial disease is often inadequate and mostly palliative. Advancements in diagnostic technology improved the molecular diagnosis of previously unresolved cases, and they provide new insight into the pathogenesis and genetic changes in mitochondrial DNA diseases.
Asunto(s)
ADN Mitocondrial/genética , Edición Génica/métodos , Terapia Genética/métodos , Mitocondrias/genética , Enfermedades Mitocondriales/genética , Acidosis Láctica/congénito , Acidosis Láctica/genética , Acidosis Láctica/metabolismo , Análisis Mutacional de ADN , ADN Mitocondrial/metabolismo , Epilepsias Mioclónicas/congénito , Epilepsias Mioclónicas/genética , Epilepsias Mioclónicas/terapia , Humanos , Enfermedad de Leigh/genética , Enfermedad de Leigh/metabolismo , Enfermedad de Leigh/terapia , Mitocondrias/metabolismo , Mitocondrias/patología , Enfermedades Mitocondriales/metabolismo , Enfermedades Mitocondriales/terapia , Encefalomiopatías Mitocondriales/congénito , Encefalomiopatías Mitocondriales/genética , Encefalomiopatías Mitocondriales/metabolismo , Mutación , Atrofia Óptica Hereditaria de Leber/genética , Atrofia Óptica Hereditaria de Leber/metabolismoRESUMEN
Mitochondrial encephalomyopathies comprise a group of heterogeneous disorders resulting from impaired oxidative phosphorylation (OxPhos). Among a variety of symptoms progressive external ophthalmoplegia (PEO) seems to be the most common. The aim of this study is to present clinical and genetic characteristics of Polish patients with PEO. Clinical, electrophysiological, neuroradiological, and morphological data of 84 patients were analyzed. Genetic studies of mitochondrial DNA (mtDNA) were performed in all patients. Among nuclear DNA (nDNA) genes POLG was sequenced in 41 patients, TWNK (C10orf2) in 13 patients, and RNASEH1 in 2 patients. Total of 27 patients were included in the chronic progressive external ophthalmoplegia (CPEO) group, 24 in the CPEO+ group. Twenty-six patients had mitochondrial encephalomyopathy (ME), six patients Kearns-Sayre syndrome (KSS), and one patient sensory ataxic neuropathy, dysarthria, ophthalmoparesis (SANDO) syndrome. Genetic analysis of nDNA genes revealed the presence of pathogenic or possibly pathogenic variants in the POLG gene in nine patients, the TWNK gene in five patients and the RNASEH1 gene in two patients. Detailed patients' history and careful assessment of family history are essential in the diagnostic work-up. Genetic studies of both mtDNA and nDNA are necessary for the final diagnosis of progressive external ophthalmoplegia and for genetic counseling.
Asunto(s)
ADN Helicasas/genética , ADN Polimerasa gamma/genética , Síndrome de Kearns-Sayre/genética , Enfermedades Mitocondriales/genética , Encefalomiopatías Mitocondriales/genética , Proteínas Mitocondriales/genética , Oftalmoplejía Externa Progresiva Crónica/genética , Ribonucleasa H/genética , Adolescente , Adulto , Anciano , Cerebelo/diagnóstico por imagen , Cerebelo/metabolismo , Cerebelo/patología , Cerebro/diagnóstico por imagen , Cerebro/metabolismo , Cerebro/patología , Niño , ADN Helicasas/metabolismo , ADN Polimerasa gamma/metabolismo , ADN Mitocondrial/genética , ADN Mitocondrial/metabolismo , Diagnóstico Diferencial , Femenino , Expresión Génica , Humanos , Síndrome de Kearns-Sayre/diagnóstico por imagen , Síndrome de Kearns-Sayre/metabolismo , Síndrome de Kearns-Sayre/patología , Masculino , Persona de Mediana Edad , Mitocondrias/metabolismo , Mitocondrias/patología , Enfermedades Mitocondriales/diagnóstico por imagen , Enfermedades Mitocondriales/metabolismo , Enfermedades Mitocondriales/patología , Encefalomiopatías Mitocondriales/diagnóstico por imagen , Encefalomiopatías Mitocondriales/metabolismo , Encefalomiopatías Mitocondriales/patología , Proteínas Mitocondriales/metabolismo , Músculo Esquelético/metabolismo , Músculo Esquelético/patología , Oftalmoplejía Externa Progresiva Crónica/diagnóstico por imagen , Oftalmoplejía Externa Progresiva Crónica/metabolismo , Oftalmoplejía Externa Progresiva Crónica/patología , Linaje , Polonia , Polimorfismo Genético , Ribonucleasa H/metabolismo , Eliminación de SecuenciaRESUMEN
Mitochondrial disorders are clinically and genetically heterogeneous and are associated with a variety of disease mechanisms. Defects of mitochondrial protein synthesis account for the largest subgroup of disorders manifesting with impaired respiratory chain capacity; yet, only a few have been linked to dysfunction in the protein components of the mitochondrial ribosomes. Here, we report a subject presenting with dyskinetic cerebral palsy and partial agenesis of the corpus callosum, while histochemical and biochemical analyses of skeletal muscle revealed signs of mitochondrial myopathy. Using exome sequencing, we identified a homozygous variant c.215C>T in MRPS25, which encodes for a structural component of the 28S small subunit of the mitochondrial ribosome (mS25). The variant segregated with the disease and substitutes a highly conserved proline residue with leucine (p.P72L) that, based on the high-resolution structure of the 28S ribosome, is predicted to compromise inter-protein contacts and destabilize the small subunit. Concordant with the in silico analysis, patient's fibroblasts showed decreased levels of MRPS25 and other components of the 28S subunit. Moreover, assembled 28S subunits were scarce in the fibroblasts with mutant mS25 leading to impaired mitochondrial translation and decreased levels of multiple respiratory chain subunits. Crucially, these abnormalities were rescued by transgenic expression of wild-type MRPS25 in the mutant fibroblasts. Collectively, our data demonstrate the pathogenicity of the p.P72L variant and identify MRPS25 mutations as a new cause of mitochondrial translation defect.
Asunto(s)
Mitocondrias/genética , Encefalomiopatías Mitocondriales/genética , Proteínas Mitocondriales/genética , Mutación , Biosíntesis de Proteínas , Proteínas Ribosómicas/genética , Adulto , Biomarcadores , Fibroblastos/metabolismo , Predisposición Genética a la Enfermedad , Homocigoto , Humanos , Imagen por Resonancia Magnética , Masculino , Mitocondrias/metabolismo , Encefalomiopatías Mitocondriales/diagnóstico , Encefalomiopatías Mitocondriales/metabolismo , Modelos Biológicos , Linaje , Fenotipo , Secuenciación del ExomaRESUMEN
Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is a devastating disease caused by mutations in TYMP, which encodes thymidine phosphorylase (TP). In MNGIE patients, TP dysfunction results in systemic thymidine and deoxyuridine overload, which interferes with mitochondrial DNA replication. Preclinical studies have shown that gene therapy using a lentiviral vector targeted to hematopoietic stem cells or an adeno-associated virus (AAV) vector transcriptionally targeted to liver are feasible approaches to treat MNGIE. Here, we studied the effect of various promoters (thyroxine-binding globulin [TBG], phosphoglycerate kinase [PGK], hybrid liver-specific promoter [HLP], and alpha-1-antitrypsin [AAT]) and DNA configuration (single stranded or self complementary) on expression of the TYMP transgene in the AAV8 serotype in a murine model of MNGIE. All vectors restored liver TP activity and normalized nucleoside homeostasis in mice. However, the liver-specific promoters TBG, HLP, and AAT were more effective than the constitutive PGK promoter, and the self-complementary DNA configuration did not provide any therapeutic advantage over the single-stranded configuration. Among all constructs, only AAV-AAT was effective in all mice treated at the lowest dose (5 × 1010 vector genomes/kg). As use of the AAT promoter will likely minimize the dose needed to achieve clinical efficacy as compared to the other promoters tested, we propose using the AAT promoter in the vector eventually designed for clinical use.
Asunto(s)
Dependovirus/genética , Expresión Génica , Terapia Genética , Vectores Genéticos/genética , Encefalomiopatías Mitocondriales/genética , Encefalomiopatías Mitocondriales/terapia , Regiones Promotoras Genéticas , alfa 1-Antitripsina/genética , Animales , Modelos Animales de Enfermedad , Orden Génico , Terapia Genética/métodos , Vectores Genéticos/administración & dosificación , Homeostasis , Hígado/metabolismo , Hígado/patología , Ratones , Ratones Noqueados , Mitocondrias Hepáticas/genética , Mitocondrias Hepáticas/metabolismo , Encefalomiopatías Mitocondriales/metabolismo , Timidina Fosforilasa/genética , Transducción Genética , alfa 1-Antitripsina/metabolismoRESUMEN
BACKGROUND: The vast majority of mitochondrial disorders have limited the clinical management to palliative care. Rapamycin has emerged as a potential therapeutic drug for mitochondrial diseases since it has shown therapeutic benefits in a few mouse models of mitochondrial disorders. However, the underlying therapeutic mechanism is unclear, the minimal effective dose needs to be defined and whether this therapy can be generally used is unknown. METHODS: We have evaluated whether low and high doses of rapamycin administration may result in therapeutic effects in a mouse model (Coq9R239X) of mitochondrial encephalopathy due to CoQ deficiency. The evaluation involved phenotypic, molecular, image (histopathology and MRI), metabolomics, transcriptomics and bioenergetics analyses. FINDINGS: Low dose of rapamycin induces metabolic changes in liver and transcriptomics modifications in midbrain. The high dose of rapamycin induces further changes in the transcriptomics profile in midbrain due to the general inhibition of mTORC1. However, neither low nor high dose of rapamycin were able to improve the mitochondrial bioenergetics, the brain injuries and the phenotypic characteristics of Coq9R239X mice, resulting in the lack of efficacy for increasing the survival. INTERPRETATION: These results may be due to the lack of microgliosis-derived neuroinflammation, the limitation to induce autophagy, or the need of a functional CoQ-junction. Therefore, the translation of rapamycin therapy into the clinic for patients with mitochondrial disorders requires, at least, the consideration of the particularities of each mitochondrial disease. FUND: Supported by the grants from "Fundación Isabel Gemio - Federación Española de Enfermedades Neuromusculares - Federación FEDER" (TSR-1), the NIH (P01HD080642) and the ERC (Stg-337327).
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Enfermedades Mitocondriales/tratamiento farmacológico , Sirolimus/uso terapéutico , Animales , Autofagia , Respiración de la Célula/efectos de los fármacos , Respiración de la Célula/genética , Modelos Animales de Enfermedad , Perfilación de la Expresión Génica , Humanos , Metabolómica/métodos , Ratones , Mitocondrias/efectos de los fármacos , Mitocondrias/genética , Mitocondrias/metabolismo , Enfermedades Mitocondriales/diagnóstico , Enfermedades Mitocondriales/etiología , Encefalomiopatías Mitocondriales/tratamiento farmacológico , Encefalomiopatías Mitocondriales/genética , Encefalomiopatías Mitocondriales/metabolismo , Fenotipo , Sirolimus/administración & dosificación , Sirolimus/efectos adversos , Sirolimus/farmacocinética , Resultado del Tratamiento , Ubiquinona/análogos & derivados , Ubiquinona/genética , Ubiquinona/metabolismoRESUMEN
The mitochondrial intramembrane rhomboid protease PARL has been implicated in diverse functions in vitro, but its physiological role in vivo remains unclear. Here we show that Parl ablation in mouse causes a necrotizing encephalomyelopathy similar to Leigh syndrome, a mitochondrial disease characterized by disrupted energy production. Mice with conditional PARL deficiency in the nervous system, but not in muscle, develop a similar phenotype as germline Parl KOs, demonstrating the vital role of PARL in neurological homeostasis. Genetic modification of two major PARL substrates, PINK1 and PGAM5, do not modify this severe neurological phenotype. Parl-/- brain mitochondria are affected by progressive ultrastructural changes and by defects in Complex III (CIII) activity, coenzyme Q (CoQ) biosynthesis, and mitochondrial calcium metabolism. PARL is necessary for the stable expression of TTC19, which is required for CIII activity, and of COQ4, which is essential in CoQ biosynthesis. Thus, PARL plays a previously overlooked constitutive role in the maintenance of the respiratory chain in the nervous system, and its deficiency causes progressive mitochondrial dysfunction and structural abnormalities leading to neuronal necrosis and Leigh-like syndrome.
Asunto(s)
Complejo III de Transporte de Electrones/metabolismo , Enfermedad de Leigh/etiología , Metaloproteasas/deficiencia , Proteínas Mitocondriales/deficiencia , Ubiquinona/metabolismo , Animales , Encéfalo/metabolismo , Calcio/metabolismo , Enfermedad de Leigh/metabolismo , Enfermedad de Leigh/fisiopatología , Hígado/metabolismo , Masculino , Potencial de la Membrana Mitocondrial , Ratones , Ratones Noqueados , Mitocondrias/metabolismo , Encefalomiopatías Mitocondriales/metabolismo , Encefalomiopatías Mitocondriales/fisiopatología , Músculo Esquelético/metabolismo , Especies Reactivas de Oxígeno/metabolismoRESUMEN
Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is a rare and fatal inherited metabolic disorder due to mutations in the nuclear TYMP gene and leads to a deficiency in the enzyme thymidine phosphorylase. This results in an accumulation of the deoxynucleosides, thymidine and deoxyuridine in the cellular and extracellular compartments, ultimately leading to mitochondrial failure. The understanding of the precise molecular mechanisms that underlie the disease pathology is limited, being hampered by the rarity of the disorder. Expression profiling of serum based mircoRNAs and subsequent bioinformatical analyses provide an approach to facilitate the identity of dysregulated genes and signalling pathways potentially involved in the pathogenesis of MNGIE.
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MicroARNs/metabolismo , Encefalomiopatías Mitocondriales/genética , Timidina Fosforilasa/metabolismo , Biología Computacional/métodos , Desoxiuridina/metabolismo , Regulación de la Expresión Génica , Humanos , Mitocondrias/genética , Encefalomiopatías Mitocondriales/metabolismo , Mutación , Nucleotidasas , Transducción de Señal , Timidina/metabolismoRESUMEN
Mutations in ATP6 gene are frequent causes of mitochondrial encephalomyopathies. ATP6 gene encodes one subunit of complexâ ¤. The present study described a missense mutation in ATP6 gene in a 8-year-old Chinese boy with mitochondrial encephalomyopathy. We identified one missense mutation in ATP6 gene (m.8914C>T) by mitochondrial DNA sequencing. This mutation altered the amino acid proline in serine, and alterative protein is predicted to be harmful. The mutation load in blood sample of patient is 59.49%. Activity of all mitochondrial complexes in blood are normal, however, the total function of mitochondrial oxidative phosphorylation were declined (including pathwayâ , pathwayâ ¡ and pathwayâ £). The missense mutation (m.8914C>T) in ATP6 gene could result in abnormal function of complexV and is related with mitochondrial encephalomyopathy.
Asunto(s)
Encefalomiopatías Mitocondriales/genética , Encefalomiopatías Mitocondriales/metabolismo , ATPasas de Translocación de Protón Mitocondriales/genética , ATPasas de Translocación de Protón Mitocondriales/metabolismo , Mutación Missense/genética , Niño , Humanos , MasculinoRESUMEN
We examine the effect of oxidative stress on the stability of mitochondrial respiratory complexes and their association into supercomplexes (SCs) in the neuron-specific Rieske iron sulfur protein (RISP) and COX10 knockout (KO) mice. Previously we reported that these two models display different grades of oxidative stress in distinct brain regions. Using blue native gel electrophoresis, we observed a redistribution of the architecture of SCs in KO mice. Brain regions with moderate levels of oxidative stress (cingulate cortex of both COX10 and RISP KO and hippocampus of the RISP KO) showed a significant increase in the levels of high molecular weight (HMW) SCs. High levels of oxidative stress in the piriform cortex of the RISP KO negatively impacted the stability of CI, CIII and SCs. Treatment of the RISP KO with the mitochondrial targeted antioxidant mitoTEMPO preserved the stability of respiratory complexes and formation of SCs in the piriform cortex and increased the levels of glutathione peroxidase. These results suggest that mild to moderate levels of oxidative stress can modulate SCs into a more favorable architecture of HMW SCs to cope with rising levels of free radicals and cover the energetic needs.