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1.
Nature ; 594(7861): 117-123, 2021 06.
Artículo en Inglés | MEDLINE | ID: mdl-34012113

RESUMEN

The human genome expresses thousands of natural antisense transcripts (NAT) that can regulate epigenetic state, transcription, RNA stability or translation of their overlapping genes1,2. Here we describe MAPT-AS1, a brain-enriched NAT that is conserved in primates and contains an embedded mammalian-wide interspersed repeat (MIR), which represses tau translation by competing for ribosomal RNA pairing with the MAPT mRNA internal ribosome entry site3. MAPT encodes tau, a neuronal intrinsically disordered protein (IDP) that stabilizes axonal microtubules. Hyperphosphorylated, aggregation-prone tau forms the hallmark inclusions of tauopathies4. Mutations in MAPT cause familial frontotemporal dementia, and common variations forming the MAPT H1 haplotype are a significant risk factor in many tauopathies5 and Parkinson's disease. Notably, expression of MAPT-AS1 or minimal essential sequences from MAPT-AS1 (including MIR) reduces-whereas silencing MAPT-AS1 expression increases-neuronal tau levels, and correlate with tau pathology in human brain. Moreover, we identified many additional NATs with embedded MIRs (MIR-NATs), which are overrepresented at coding genes linked to neurodegeneration and/or encoding IDPs, and confirmed MIR-NAT-mediated translational control of one such gene, PLCG1. These results demonstrate a key role for MAPT-AS1 in tauopathies and reveal a potentially broad contribution of MIR-NATs to the tightly controlled translation of IDPs6, with particular relevance for proteostasis in neurodegeneration.


Asunto(s)
Biosíntesis de Proteínas/genética , Proteostasis/genética , ARN sin Sentido/genética , Tauopatías/genética , Tauopatías/metabolismo , Proteínas tau/genética , Proteínas tau/metabolismo , Anciano , Animales , Sitios de Unión , Encéfalo/metabolismo , Encéfalo/patología , Estudios de Casos y Controles , Diferenciación Celular , Progresión de la Enfermedad , Femenino , Humanos , Sitios Internos de Entrada al Ribosoma/genética , Masculino , Ratones , Ratones Transgénicos , Persona de Mediana Edad , Neuronas/metabolismo , Neuronas/patología , Ribosomas/metabolismo , Proteínas tau/biosíntesis
2.
Mol Cell Neurosci ; 109: 103553, 2020 12.
Artículo en Inglés | MEDLINE | ID: mdl-32956830

RESUMEN

Frontotemporal dementia (FTD) describes a group of clinically heterogeneous conditions that frequently affect people under the age of 65 (Le Ber et al., 2013). There are multiple genetic causes of FTD, including coding or splice-site mutations in MAPT, GRN mutations that lead to haploinsufficiency of progranulin protein, and a hexanucleotide GGGGCC repeat expansion in C9ORF72. Pathologically, FTD is characterised by abnormal protein accumulations in neurons and glia. These aggregates can be composed of the microtubule-associated protein tau (observed in FTD with MAPT mutations), the DNA/RNA-binding protein TDP-43 (seen in FTD with mutations in GRN or C9ORF72 repeat expansions) or dipeptide proteins generated by repeat associated non-ATG translation of the C9ORF72 repeat expansion. There are currently no disease-modifying therapies for FTD and the availability of in vitro models that recapitulate pathologies in a disease-relevant cell type would accelerate the development of novel therapeutics. It is now possible to generate patient-specific stem cells through the reprogramming of somatic cells from a patient with a genotype/phenotype of interest into induced pluripotent stem cells (iPSCs). iPSCs can subsequently be differentiated into a plethora of cell types including neurons, astrocytes and microglia. Using this approach has allowed researchers to generate in vitro models of genetic FTD in human cell types that are largely inaccessible during life. In this review we explore the recent progress in the use of iPSCs to model FTD, and consider the merits, limitations and future prospects of this approach.


Asunto(s)
Demencia Frontotemporal/genética , Células Madre Pluripotentes Inducidas/metabolismo , Proteínas tau/genética , Axones/metabolismo , Transporte Biológico , Proteína C9orf72/genética , Proteína C9orf72/fisiología , Diferenciación Celular , Técnicas de Reprogramación Celular , Expansión de las Repeticiones de ADN , Proteínas de Unión al ADN/fisiología , Regulación del Desarrollo de la Expresión Génica , Humanos , Intrones/genética , Microtúbulos/fisiología , Mitocondrias/fisiología , Modelos Genéticos , Mutación Missense , Degeneración Nerviosa , Neuroglía/metabolismo , Neuroglía/patología , Neuronas/metabolismo , Neuronas/patología , Organoides , Progranulinas/genética , Progranulinas/fisiología , Agregación Patológica de Proteínas , Isoformas de Proteínas , Empalme de Proteína , Especies Reactivas de Oxígeno , Proteínas tau/química , Proteínas tau/metabolismo
3.
J Biol Chem ; 292(21): 8907-8917, 2017 05 26.
Artículo en Inglés | MEDLINE | ID: mdl-28360103

RESUMEN

Mutations in the gene encoding valosin-containing protein (VCP) lead to multisystem proteinopathies including frontotemporal dementia. We have previously shown that patient-derived VCP mutant fibroblasts exhibit lower mitochondrial membrane potential, uncoupled respiration, and reduced ATP levels. This study addresses the underlying basis for mitochondrial uncoupling using VCP knockdown neuroblastoma cell lines, induced pluripotent stem cells (iPSCs), and iPSC-derived cortical neurons from patients with pathogenic mutations in VCP Using fluorescent live cell imaging and respiration analysis we demonstrate a VCP mutation/knockdown-induced dysregulation in the adenine nucleotide translocase, which results in a slower rate of ADP or ATP translocation across the mitochondrial membranes. This deregulation can explain the mitochondrial uncoupling and lower ATP levels in VCP mutation-bearing neurons via reduced ADP availability for ATP synthesis. This study provides evidence for a role of adenine nucleotide translocase in the mechanism underlying altered mitochondrial function in VCP-related degeneration, and this new insight may inform efforts to better understand and manage neurodegenerative disease and other proteinopathies.


Asunto(s)
Adenosina Difosfato/metabolismo , Adenosina Trifosfatasas , Adenosina Trifosfato/metabolismo , Proteínas de Ciclo Celular , Membranas Mitocondriales/metabolismo , Mutación , Neuronas/metabolismo , Adenosina Difosfato/genética , Adenosina Trifosfatasas/genética , Adenosina Trifosfatasas/metabolismo , Adenosina Trifosfato/genética , Transporte Biológico Activo/fisiología , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Línea Celular Tumoral , Humanos , Células Madre Pluripotentes Inducidas/metabolismo , Células Madre Pluripotentes Inducidas/patología , Translocasas Mitocondriales de ADP y ATP/genética , Translocasas Mitocondriales de ADP y ATP/metabolismo , Enfermedades Neurodegenerativas/genética , Enfermedades Neurodegenerativas/metabolismo , Neuronas/patología , Deficiencias en la Proteostasis/genética , Deficiencias en la Proteostasis/metabolismo , Proteína que Contiene Valosina
4.
Hum Mol Genet ; 24(18): 5260-9, 2015 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-26136155

RESUMEN

The alternative splicing of the tau gene, MAPT, generates six protein isoforms in the adult human central nervous system (CNS). Tau splicing is developmentally regulated and dysregulated in disease. Mutations in MAPT that alter tau splicing cause frontotemporal dementia (FTD) with tau pathology, providing evidence for a causal link between altered tau splicing and disease. The use of induced pluripotent stem cell (iPSC)-derived neurons has revolutionized the way we model neurological disease in vitro. However, as most tau mutations are located within or around the alternatively spliced exon 10, it is important that iPSC-neurons splice tau appropriately in order to be used as disease models. To address this issue, we analyzed the expression and splicing of tau in iPSC-derived cortical neurons from control patients and FTD patients with the 10 + 16 intronic mutation in MAPT. We show that control neurons only express the fetal tau isoform (0N3R), even at extended time points of 100 days in vitro. Neurons from FTD patients with the 10 + 16 mutation in MAPT express both 0N3R and 0N4R tau isoforms, demonstrating that this mutation overrides the developmental regulation of exon 10 inclusion in our in vitro model. Further, at extended time points of 365 days in vitro, we observe a switch in tau splicing to include six tau isoforms as seen in the adult human CNS. Our results demonstrate the importance of neuronal maturity for use in in vitro modeling and provide a system that will be important for understanding the functional consequences of altered tau splicing.


Asunto(s)
Empalme Alternativo , Demencia Frontotemporal/genética , Mutación , Neuronas/metabolismo , Células Madre/metabolismo , Proteínas tau/genética , Biomarcadores , Diferenciación Celular , Línea Celular , Corteza Cerebral/citología , Corteza Cerebral/metabolismo , Fibroblastos/citología , Fibroblastos/metabolismo , Demencia Frontotemporal/metabolismo , Haplotipos , Humanos , Células Madre Pluripotentes Inducidas/citología , Células Madre Pluripotentes Inducidas/metabolismo , Lactante , Recién Nacido , Intrones , Neuronas/citología , Fosforilación , Sitios de Empalme de ARN , Células Madre/citología
5.
Brain ; 139(Pt 7): 1904-18, 2016 07.
Artículo en Inglés | MEDLINE | ID: mdl-27217339

RESUMEN

The hereditary spastic paraplegias are a heterogeneous group of degenerative disorders that are clinically classified as either pure with predominant lower limb spasticity, or complex where spastic paraplegia is complicated with additional neurological features, and are inherited in autosomal dominant, autosomal recessive or X-linked patterns. Genetic defects have been identified in over 40 different genes, with more than 70 loci in total. Complex recessive spastic paraplegias have in the past been frequently associated with mutations in SPG11 (spatacsin), ZFYVE26/SPG15, SPG7 (paraplegin) and a handful of other rare genes, but many cases remain genetically undefined. The overlap with other neurodegenerative disorders has been implied in a small number of reports, but not in larger disease series. This deficiency has been largely due to the lack of suitable high throughput techniques to investigate the genetic basis of disease, but the recent availability of next generation sequencing can facilitate the identification of disease-causing mutations even in extremely heterogeneous disorders. We investigated a series of 97 index cases with complex spastic paraplegia referred to a tertiary referral neurology centre in London for diagnosis or management. The mean age of onset was 16 years (range 3 to 39). The SPG11 gene was first analysed, revealing homozygous or compound heterozygous mutations in 30/97 (30.9%) of probands, the largest SPG11 series reported to date, and by far the most common cause of complex spastic paraplegia in the UK, with severe and progressive clinical features and other neurological manifestations, linked with magnetic resonance imaging defects. Given the high frequency of SPG11 mutations, we studied the autophagic response to starvation in eight affected SPG11 cases and control fibroblast cell lines, but in our restricted study we did not observe correlations between disease status and autophagic or lysosomal markers. In the remaining cases, next generation sequencing was carried out revealing variants in a number of other known complex spastic paraplegia genes, including five in SPG7 (5/97), four in FA2H (also known as SPG35) (4/97) and two in ZFYVE26/SPG15 Variants were identified in genes usually associated with pure spastic paraplegia and also in the Parkinson's disease-associated gene ATP13A2, neuronal ceroid lipofuscinosis gene TPP1 and the hereditary motor and sensory neuropathy DNMT1 gene, highlighting the genetic heterogeneity of spastic paraplegia. No plausible genetic cause was identified in 51% of probands, likely indicating the existence of as yet unidentified genes.


Asunto(s)
Proteínas/genética , Paraplejía Espástica Hereditaria/genética , Paraplejía Espástica Hereditaria/fisiopatología , Adolescente , Adulto , Línea Celular , Niño , Preescolar , Estudios de Cohortes , Femenino , Fibroblastos , Humanos , Masculino , Mutación , Linaje , Fenotipo , Paraplejía Espástica Hereditaria/diagnóstico por imagen , Tripeptidil Peptidasa 1 , Reino Unido , Adulto Joven
6.
Am J Hum Genet ; 91(6): 1041-50, 2012 Dec 07.
Artículo en Inglés | MEDLINE | ID: mdl-23200863

RESUMEN

In this study, we combined linkage analysis with whole-exome sequencing of two individuals to identify candidate causal variants in a moderately-sized UK kindred exhibiting autosomal-dominant inheritance of craniocervical dystonia. Subsequent screening of these candidate causal variants in a large number of familial and sporadic cases of cervical dystonia led to the identification of a total of six putatively pathogenic mutations in ANO3, a gene encoding a predicted Ca(2+)-gated chloride channel that we show to be highly expressed in the striatum. Functional studies using Ca(2+) imaging in case and control fibroblasts demonstrated clear abnormalities in endoplasmic-reticulum-dependent Ca(2+) signaling. We conclude that mutations in ANO3 are a cause of autosomal-dominant craniocervical dystonia. The locus DYT23 has been reserved as a synonym for this gene. The implication of an ion channel in the pathogenesis of dystonia provides insights into an alternative mechanism that opens fresh avenues for further research.


Asunto(s)
Canales de Cloruro/genética , Genes Dominantes , Mutación , Tortícolis/genética , Secuencia de Aminoácidos , Anoctaminas , Secuencia de Bases , Señalización del Calcio , Canales de Cloruro/metabolismo , Cuerpo Estriado/metabolismo , Distonía , Retículo Endoplásmico/metabolismo , Exoma , Femenino , Fibroblastos , Regulación de la Expresión Génica , Ligamiento Genético , Secuenciación de Nucleótidos de Alto Rendimiento , Humanos , Canales Iónicos/genética , Masculino , Datos de Secuencia Molecular , Linaje , Fenotipo , Alineación de Secuencia , Tortícolis/metabolismo
7.
Hum Mol Genet ; 21(15): 3500-12, 2012 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-22556362

RESUMEN

Rare mutations in the gene encoding for tau (MAPT, microtubule-associated protein tau) cause frontotemporal dementia-spectrum (FTD-s) disorders, including FTD, progressive supranuclear palsy (PSP) and corticobasal syndrome, and a common extended haplotype spanning across the MAPT locus is associated with increased risk of PSP and Parkinson's disease. We identified a rare tau variant (p.A152T) in a patient with a clinical diagnosis of PSP and assessed its frequency in multiple independent series of patients with neurodegenerative conditions and controls, in a total of 15 369 subjects. Tau p.A152T significantly increases the risk for both FTD-s (n = 2139, OR = 3.0, CI: 1.6-5.6, P = 0.0005) and Alzheimer's disease (AD) (n = 3345, OR = 2.3, CI: 1.3-4.2, P = 0.004) compared with 9047 controls. Functionally, p.A152T (i) decreases the binding of tau to microtubules and therefore promotes microtubule assembly less efficiently; and (ii) reduces the tendency to form abnormal fibers. However, there is a pronounced increase in the formation of tau oligomers. Importantly, these findings suggest that other regions of the tau protein may be crucial in regulating normal function, as the p.A152 residue is distal to the domains considered responsible for microtubule interactions or aggregation. These data provide both the first genetic evidence and functional studies supporting the role of MAPT p.A152T as a rare risk factor for both FTD-s and AD and the concept that rare variants can increase the risk for relatively common, complex neurodegenerative diseases, but since no clear significance threshold for rare genetic variation has been established, some caution is warranted until the findings are further replicated.


Asunto(s)
Enfermedad de Alzheimer/genética , Demencia Frontotemporal/genética , Variación Genética , Proteínas tau/genética , Anciano , Enfermedad de Alzheimer/epidemiología , Demencia Frontotemporal/epidemiología , Predisposición Genética a la Enfermedad , Genotipo , Haplotipos , Humanos , Persona de Mediana Edad , Riesgo
8.
J Neurol Neurosurg Psychiatry ; 85(5): 493-8, 2014 May.
Artículo en Inglés | MEDLINE | ID: mdl-24218524

RESUMEN

BACKGROUND: The autosomal-recessive cerebellar ataxias (ARCA) are a clinically and genetically heterogeneous group of neurodegenerative disorders. The large number of ARCA genes leads to delay and difficulties obtaining an exact diagnosis in many patients and families. Ubiquinone (CoQ10) deficiency is one of the potentially treatable causes of ARCAs as some patients respond to CoQ10 supplementation. The AarF domain containing kinase 3 gene (ADCK3) is one of several genes associated with CoQ10 deficiency. ADCK3 encodes a mitochondrial protein which functions as an electron-transfer membrane protein complex in the mitochondrial respiratory chain (MRC). METHODS: We report two siblings from a consanguineous Pakistani family who presented with cerebellar ataxia and severe myoclonus from adolescence. Whole exome sequencing and biochemical assessment of fibroblasts were performed in the index patient. RESULTS: A novel homozygous frameshift mutation in ADCK3 (p.Ser616Leufs*114), was identified in both siblings. This frameshift mutation results in the loss of the stop codon, extending the coding protein by 81 amino acids. Significant CoQ10 deficiency and reduced MRC enzyme activities in the index patient's fibroblasts suggested that the mutant protein may reduce the efficiency of mitochondrial electron transfer. CoQ10 supplementation was initiated following these genetic and biochemical analyses. She gained substantial improvement in myoclonic movements, ataxic gait and dysarthric speech after treatment. CONCLUSION: This study highlights the importance of diagnosing ADCK3 mutations and the potential benefit of treatment for patients. The identification of this new mutation broadens the phenotypic spectrum associated with ADCK3 mutations and provides further understanding of their pathogenic mechanism.


Asunto(s)
Ataxia Cerebelosa/genética , Mutación del Sistema de Lectura/genética , Proteínas Quinasas/genética , Adulto , Ataxia Cerebelosa/metabolismo , Ataxia Cerebelosa/terapia , Consanguinidad , Femenino , Humanos , Proteínas Mitocondriales/genética , Linaje , Ubiquinona/análogos & derivados , Ubiquinona/deficiencia
9.
Aging Cell ; 21(2): e13549, 2022 02.
Artículo en Inglés | MEDLINE | ID: mdl-35026048

RESUMEN

Hexanucleotide repeat expansions in C9orf72 are the most common cause of familial amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). The mechanisms by which the expansions cause disease are not properly understood but a favoured route involves its translation into dipeptide repeat (DPR) polypeptides, some of which are neurotoxic. However, the precise targets for mutant C9orf72 and DPR toxicity are not fully clear, and damage to several neuronal functions has been described. Many of these functions are regulated by signalling between the endoplasmic reticulum (ER) and mitochondria. ER-mitochondria signalling requires close physical contacts between the two organelles that are mediated by the VAPB-PTPIP51 'tethering' proteins. Here, we show that ER-mitochondria signalling and the VAPB-PTPIP51 tethers are disrupted in neurons derived from induced pluripotent stem (iPS) cells from patients carrying ALS/FTD pathogenic C9orf72 expansions and in affected neurons in mutant C9orf72 transgenic mice. In these mice, disruption of the VAPB-PTPIP51 tethers occurs prior to disease onset suggesting that it contributes to the pathogenic process. We also show that neurotoxic DPRs disrupt the VAPB-PTPIP51 interaction and ER-mitochondria contacts and that this may involve activation of glycogen synthase kinases-3ß (GSK3ß), a known negative regulator of VAPB-PTPIP51 binding. Finally, we show that these DPRs disrupt delivery of Ca2+ from ER stores to mitochondria, which is a primary function of the VAPB-PTPIP51 tethers. This delivery regulates a number of key neuronal functions that are damaged in ALS/FTD including bioenergetics, autophagy and synaptic function. Our findings reveal a new molecular target for mutant C9orf72-mediated toxicity.


Asunto(s)
Esclerosis Amiotrófica Lateral , Demencia Frontotemporal , Esclerosis Amiotrófica Lateral/patología , Animales , Proteína C9orf72/genética , Proteína C9orf72/metabolismo , Calcio/metabolismo , Retículo Endoplásmico/metabolismo , Demencia Frontotemporal/genética , Demencia Frontotemporal/metabolismo , Demencia Frontotemporal/patología , Humanos , Ratones , Mitocondrias/metabolismo , Proteínas Mitocondriales/metabolismo , Proteínas Tirosina Fosfatasas/metabolismo
10.
Mol Neurobiol ; 56(1): 335, 2019 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-29779174

RESUMEN

The original version of this article unfortunately contained mistake. The author's family name "Kov ac" was written with space thus this should be corrected to "Kovac".

11.
Mol Neurobiol ; 56(1): 321-334, 2019 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-29704197

RESUMEN

Mutations in genes affecting mitochondrial proteins are increasingly recognised in patients with epilepsy, but the factors determining cell fate during seizure activity in these mutations remain unknown. Fluorescent dye imaging techniques were applied to fibroblast cell lines from patients suffering from common mitochondrial mutations and to age-matched controls. Using live cell imaging techniques in fibroblasts, we show that fibroblasts with mutations in the mitochondrial genome had reduced mitochondrial membrane potential and NADH pools and higher redox indices, indicative of respiratory chain dysfunction. Increasing concentrations of ferutinin, a Ca2+ ionophore, led to oscillatory Ca2+ signals in fibroblasts resembling dynamic Ca2+ changes that occur during seizure-like activity. Co-monitoring of mitochondrial membrane potential (ΔΨm) changes induced by ferutinin showed accelerated membrane depolarisation and cell collapse in fibroblasts with mutations in the mitochondrial genome when compared to controls. Ca2+ flash photolysis using caged Ca2+ confirmed impaired Ca2+ handling in fibroblasts with mitochondrial mutations. Findings indicate that intracellular Ca2+ levels cannot be compensated during periods of hyperexcitability, leading to Ca2+ overload and subsequent cell death in mitochondrial diseases.


Asunto(s)
Linaje de la Célula/genética , ADN Mitocondrial/genética , Metabolismo Energético , Mutación/genética , Convulsiones/genética , Convulsiones/patología , Adenosina Trifosfato/metabolismo , Calcio/metabolismo , Señalización del Calcio , Línea Celular , Respiración de la Célula , Fibroblastos/metabolismo , Fibroblastos/patología , Humanos , Potencial de la Membrana Mitocondrial , Mitocondrias/metabolismo , NAD/metabolismo , Oxidación-Reducción
12.
EMBO Mol Med ; 10(1): 22-31, 2018 01.
Artículo en Inglés | MEDLINE | ID: mdl-29113975

RESUMEN

Intronic GGGGCC repeat expansions in C9orf72 are the most common known cause of frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS), which are characterised by degeneration of cortical and motor neurons, respectively. Repeat expansions have been proposed to cause disease by both the repeat RNA forming foci that sequester RNA-binding proteins and through toxic dipeptide repeat proteins generated by repeat-associated non-ATG translation. GGGGCC repeat RNA folds into a G-quadruplex secondary structure, and we investigated whether targeting this structure is a potential therapeutic strategy. We performed a screen that identified three structurally related small molecules that specifically stabilise GGGGCC repeat G-quadruplex RNA We investigated their effect in C9orf72 patient iPSC-derived motor and cortical neurons and show that they significantly reduce RNA foci burden and the levels of dipeptide repeat proteins. Furthermore, they also reduce dipeptide repeat proteins and improve survival in vivo, in GGGGCC repeat-expressing Drosophila Therefore, small molecules that target GGGGCC repeat G-quadruplexes can ameliorate the two key pathologies associated with C9orf72 FTD/ALS These data provide proof of principle that targeting GGGGCC repeat G-quadruplexes has therapeutic potential.


Asunto(s)
Esclerosis Amiotrófica Lateral/tratamiento farmacológico , Proteína C9orf72/genética , Descubrimiento de Drogas , Demencia Frontotemporal/tratamiento farmacológico , G-Cuádruplex/efectos de los fármacos , Bibliotecas de Moléculas Pequeñas/química , Bibliotecas de Moléculas Pequeñas/farmacología , Esclerosis Amiotrófica Lateral/genética , Animales , Drosophila , Demencia Frontotemporal/genética , Humanos , ARN/química , ARN/genética , Secuencias Repetitivas de Ácidos Nucleicos/efectos de los fármacos , Bibliotecas de Moléculas Pequeñas/uso terapéutico
13.
PLoS One ; 12(9): e0184104, 2017.
Artículo en Inglés | MEDLINE | ID: mdl-28863176

RESUMEN

Mutations in PANK2 lead to neurodegeneration with brain iron accumulation. PANK2 has a role in the biosynthesis of coenzyme A (CoA) from dietary vitamin B5, but the neuropathological mechanism and reasons for iron accumulation remain unknown. In this study, atypical patient-derived fibroblasts were reprogrammed into induced pluripotent stem cells (iPSCs) and subsequently differentiated into cortical neuronal cells for studying disease mechanisms in human neurons. We observed no changes in PANK2 expression between control and patient cells, but a reduction in protein levels was apparent in patient cells. CoA homeostasis and cellular iron handling were normal, mitochondrial function was affected; displaying activated NADH-related and inhibited FADH-related respiration, resulting in increased mitochondrial membrane potential. This led to increased reactive oxygen species generation and lipid peroxidation in patient-derived neurons. These data suggest that mitochondrial deficiency is an early feature of the disease process and can be explained by altered NADH/FADH substrate supply to oxidative phosphorylation. Intriguingly, iron chelation appeared to exacerbate the mitochondrial phenotype in both control and patient neuronal cells. This raises caution for the use iron chelation therapy in general when iron accumulation is absent.


Asunto(s)
Células Madre Pluripotentes Inducidas/citología , Enfermedades Mitocondriales/fisiopatología , Neurodegeneración Asociada a Pantotenato Quinasa/fisiopatología , Fosfotransferasas (Aceptor de Grupo Alcohol)/metabolismo , Acetilcoenzima A/química , Adolescente , Biopsia , Encéfalo/metabolismo , Diferenciación Celular , Niño , Coenzima A/metabolismo , Femenino , Fibroblastos/metabolismo , Humanos , Células Madre Pluripotentes Inducidas/metabolismo , Hierro/química , Cariotipificación , Peroxidación de Lípido , Masculino , Potencial de la Membrana Mitocondrial , Mitocondrias/patología , Mutación , NAD/química , Neuronas/metabolismo , Ácido Pantoténico/química , Fenotipo , Fosfotransferasas (Aceptor de Grupo Alcohol)/genética , Plásmidos/metabolismo , Especies Reactivas de Oxígeno/metabolismo
14.
Cell Rep ; 19(9): 1739-1749, 2017 05 30.
Artículo en Inglés | MEDLINE | ID: mdl-28564594

RESUMEN

Motor neurons (MNs) and astrocytes (ACs) are implicated in the pathogenesis of amyotrophic lateral sclerosis (ALS), but their interaction and the sequence of molecular events leading to MN death remain unresolved. Here, we optimized directed differentiation of induced pluripotent stem cells (iPSCs) into highly enriched (> 85%) functional populations of spinal cord MNs and ACs. We identify significantly increased cytoplasmic TDP-43 and ER stress as primary pathogenic events in patient-specific valosin-containing protein (VCP)-mutant MNs, with secondary mitochondrial dysfunction and oxidative stress. Cumulatively, these cellular stresses result in synaptic pathology and cell death in VCP-mutant MNs. We additionally identify a cell-autonomous VCP-mutant AC survival phenotype, which is not attributable to the same molecular pathology occurring in VCP-mutant MNs. Finally, through iterative co-culture experiments, we uncover non-cell-autonomous effects of VCP-mutant ACs on both control and mutant MNs. This work elucidates molecular events and cellular interplay that could guide future therapeutic strategies in ALS.


Asunto(s)
Esclerosis Amiotrófica Lateral/metabolismo , Esclerosis Amiotrófica Lateral/patología , Astrocitos/patología , Modelos Biológicos , Neuronas Motoras/patología , Proteína que Contiene Valosina/metabolismo , Supervivencia Celular , Proteínas de Unión al ADN/metabolismo , Retículo Endoplásmico/metabolismo , Retículo Endoplásmico/ultraestructura , Estrés del Retículo Endoplásmico , Humanos , Células Madre Pluripotentes Inducidas/metabolismo , Potencial de la Membrana Mitocondrial , Mitocondrias/metabolismo , Mitocondrias/ultraestructura , Mutación/genética , Degeneración Nerviosa/patología , Neurogénesis , Estrés Oxidativo , Fenotipo , Sinapsis/patología
15.
Neurobiol Aging ; 36(1): 546.e1-7, 2015 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-25179228

RESUMEN

An expanded hexanucleotide repeat in the C9orf72 gene is the most common genetic cause of amyotrophic lateral sclerosis and frontotemporal dementia (C9ALS/FTD). Although 0-30 hexanucleotide repeats are present in the general population, expansions >500 repeats are associated with C9ALS/FTD. Large C9ALS/FTD expansions share a common haplotype and whether these expansions derive from a single founder or occur more frequently on a predisposing haplotype is yet to be determined and is relevant to disease pathomechanisms. Furthermore, although cases carrying 50-200 repeats have been described, their role and the pathogenic threshold of the expansions remain to be identified and carry importance for diagnostics and genetic counseling. We present clinical and genetic data from a UK ALS cohort and report the detailed molecular study of an atypical somatically unstable expansion of 90 repeats. Our results across different tissues provide evidence for the pathogenicity of this repeat number by showing they can somatically expand in the central nervous system to the well characterized pathogenic range. Our results support the occurrence of multiple expansion events for C9ALS/FTD.


Asunto(s)
Esclerosis Amiotrófica Lateral/genética , Estudios de Cohortes , Expansión de las Repeticiones de ADN/genética , Proteínas/genética , Proteína C9orf72 , Demencia Frontotemporal/genética , Humanos , Reino Unido
16.
Neuron ; 78(1): 57-64, 2013 Apr 10.
Artículo en Inglés | MEDLINE | ID: mdl-23498975

RESUMEN

Valosin-containing protein (VCP) is a highly expressed member of the type II AAA+ ATPase family. VCP mutations are the cause of inclusion body myopathy, Paget's disease of the bone, and frontotemporal dementia (IBMPFD) and they account for 1%-2% of familial amyotrophic lateral sclerosis (ALS). Using fibroblasts from patients carrying three independent pathogenic mutations in the VCP gene, we show that VCP deficiency causes profound mitochondrial uncoupling leading to decreased mitochondrial membrane potential and increased mitochondrial oxygen consumption. This mitochondrial uncoupling results in a significant reduction of cellular ATP production. Decreased ATP levels in VCP-deficient cells lower their energy capacity, making them more vulnerable to high energy-demanding processes such as ischemia. Our findings propose a mechanism by which pathogenic VCP mutations lead to cell death.


Asunto(s)
Adenosina Trifosfatasas/genética , Adenosina Trifosfato/metabolismo , Proteínas de Ciclo Celular/genética , Mitocondrias/genética , Mitocondrias/metabolismo , Mutación/genética , Neuronas/ultraestructura , Adenosina Trifosfatasas/deficiencia , Adulto , Anciano , Análisis de Varianza , Animales , Animales Recién Nacidos , Estudios de Casos y Controles , Proteínas de Ciclo Celular/deficiencia , Células Cultivadas , Corteza Cerebral/citología , Salud de la Familia , Femenino , Fibroblastos/metabolismo , Fibroblastos/patología , Demencia Frontotemporal/genética , Demencia Frontotemporal/metabolismo , Demencia Frontotemporal/patología , Humanos , Peroxidación de Lípido/genética , Proteínas Luminiscentes/genética , Magnesio/metabolismo , Masculino , Potencial de la Membrana Mitocondrial/genética , Ratones , Ratones Endogámicos C57BL , Persona de Mediana Edad , Mitocondrias/patología , Distrofia Muscular de Cinturas/genética , Distrofia Muscular de Cinturas/metabolismo , Distrofia Muscular de Cinturas/patología , Miositis por Cuerpos de Inclusión/genética , Miositis por Cuerpos de Inclusión/metabolismo , Miositis por Cuerpos de Inclusión/patología , NAD/metabolismo , Neuroblastoma/patología , Osteítis Deformante/genética , Osteítis Deformante/metabolismo , Osteítis Deformante/patología , Consumo de Oxígeno/genética , ARN Interferente Pequeño/genética , ARN Interferente Pequeño/metabolismo , Transfección , Proteína que Contiene Valosina
17.
PLoS One ; 7(8): e43099, 2012.
Artículo en Inglés | MEDLINE | ID: mdl-22952635

RESUMEN

Our understanding of the molecular mechanisms of many neurological disorders has been greatly enhanced by the discovery of mutations in genes linked to familial forms of these diseases. These have facilitated the generation of cell and animal models that can be used to understand the underlying molecular pathology. Recently, there has been a surge of interest in the use of patient-derived cells, due to the development of induced pluripotent stem cells and their subsequent differentiation into neurons and glia. Access to patient cell lines carrying the relevant mutations is a limiting factor for many centres wishing to pursue this research. We have therefore generated an open-access collection of fibroblast lines from patients carrying mutations linked to neurological disease. These cell lines have been deposited in the National Institute for Neurological Disorders and Stroke (NINDS) Repository at the Coriell Institute for Medical Research and can be requested by any research group for use in in vitro disease modelling. There are currently 71 mutation-defined cell lines available for request from a wide range of neurological disorders and this collection will be continually expanded. This represents a significant resource that will advance the use of patient cells as disease models by the scientific community.


Asunto(s)
Fibroblastos/citología , Mutación , Enfermedades del Sistema Nervioso/genética , Enfermedades del Sistema Nervioso/fisiopatología , Bancos de Tejidos , Acceso a la Información , Biopsia , Diferenciación Celular , Línea Celular , Proliferación Celular , Bases de Datos Factuales , Fibroblastos/metabolismo , Humanos , Inmunohistoquímica/métodos , Células Madre Pluripotentes Inducidas/citología , Modelos Genéticos
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