RESUMEN
Spinal muscular atrophy (SMA), an autosomal recessive neuromuscular disease, is the leading monogenic cause of infant mortality. Homozygous loss of the gene survival of motor neuron 1 (SMN1) causes the selective degeneration of lower motor neurons and subsequent atrophy of proximal skeletal muscles. The SMN1 protein product, survival of motor neuron (SMN), is ubiquitously expressed and is a key factor in the assembly of the core splicing machinery. The molecular mechanisms by which disruption of the broad functions of SMN leads to neurodegeneration remain unclear. We used an antisense oligonucleotide (ASO)-based inducible mouse model of SMA to investigate the SMN-specific transcriptome changes associated with neurodegeneration. We found evidence of widespread intron retention, particularly of minor U12 introns, in the spinal cord of mice 30 d after SMA induction, which was then rescued by a therapeutic ASO. Intron retention was concomitant with a strong induction of the p53 pathway and DNA damage response, manifesting as γ-H2A.X positivity in neurons of the spinal cord and brain. Widespread intron retention and markers of the DNA damage response were also observed with SMN depletion in human SH-SY5Y neuroblastoma cells and human induced pluripotent stem cell-derived motor neurons. We also found that retained introns, high in GC content, served as substrates for the formation of transcriptional R-loops. We propose that defects in intron removal in SMA promote DNA damage in part through the formation of RNA:DNA hybrid structures, leading to motor neuron death.
Asunto(s)
Daño del ADN , Intrones , Atrofia Muscular Espinal/metabolismo , Proteína 1 para la Supervivencia de la Neurona Motora/genética , Proteína 1 para la Supervivencia de la Neurona Motora/metabolismo , Animales , Modelos Animales de Enfermedad , Humanos , Ratones , Neuronas Motoras/metabolismo , Atrofia Muscular Espinal/genética , Oligonucleótidos Antisentido/genética , Oligonucleótidos Antisentido/metabolismo , Empalme del ARNRESUMEN
Neuronal ceroid lipofuscinosis (NCL) comprises â¼13 genetically distinct lysosomal disorders primarily affecting the central nervous system. Here we report successful reprograming of patient fibroblasts into induced pluripotent stem cells (iPSCs) for the two most common NCL subtypes: classic late-infantile NCL, caused by TPP1(CLN2) mutation, and juvenile NCL, caused by CLN3 mutation. CLN2/TPP1- and CLN3-iPSCs displayed overlapping but distinct biochemical and morphological abnormalities within the endosomal-lysosomal system. In neuronal derivatives, further abnormalities were observed in mitochondria, Golgi and endoplasmic reticulum. While lysosomal storage was undetectable in iPSCs, progressive disease subtype-specific storage material was evident upon neural differentiation and was rescued by reintroducing the non-mutated NCL proteins. In proof-of-concept studies, we further documented differential effects of potential small molecule TPP1 activity inducers. Fenofibrate and gemfibrozil, previously reported to induce TPP1 activity in control cells, failed to increase TPP1 activity in patient iPSC-derived neural progenitor cells. Conversely, nonsense suppression by PTC124 resulted in both an increase of TPP1 activity and attenuation of neuropathology in patient iPSC-derived neural progenitor cells. This study therefore documents the high value of this powerful new set of tools for improved drug screening and for investigating early mechanisms driving NCL pathogenesis.
Asunto(s)
Aminopeptidasas/genética , Dipeptidil-Peptidasas y Tripeptidil-Peptidasas/genética , Células Madre Pluripotentes Inducidas/metabolismo , Glicoproteínas de Membrana/genética , Modelos Neurológicos , Chaperonas Moleculares/genética , Mutación/genética , Lipofuscinosis Ceroideas Neuronales/genética , Serina Proteasas/genética , Aminopeptidasas/metabolismo , Western Blotting , Estudios de Casos y Controles , Proliferación Celular , Células Cultivadas , Dipeptidil-Peptidasas y Tripeptidil-Peptidasas/metabolismo , Electrofisiología , Retículo Endoplásmico/efectos de los fármacos , Retículo Endoplásmico/metabolismo , Fenofibrato/farmacología , Fibroblastos/efectos de los fármacos , Fibroblastos/metabolismo , Fibroblastos/patología , Gemfibrozilo/farmacología , Aparato de Golgi/efectos de los fármacos , Aparato de Golgi/metabolismo , Humanos , Técnicas para Inmunoenzimas , Células Madre Pluripotentes Inducidas/efectos de los fármacos , Células Madre Pluripotentes Inducidas/patología , Lisosomas/efectos de los fármacos , Lisosomas/metabolismo , Glicoproteínas de Membrana/metabolismo , Chaperonas Moleculares/metabolismo , Lipofuscinosis Ceroideas Neuronales/metabolismo , Lipofuscinosis Ceroideas Neuronales/patología , Neuronas/efectos de los fármacos , Neuronas/metabolismo , Neuronas/patología , Serina Proteasas/metabolismo , Tripeptidil Peptidasa 1RESUMEN
Neuronal ceroid lipofuscinoses (NCL) are a group of inherited neurodegenerative disorders with lysosomal pathology (CLN1-14). Recently, mutations in the DNAJC5/CLN4 gene, which encodes the presynaptic co-chaperone CSPα were shown to cause autosomal-dominant NCL. Although 14 NCL genes have been identified, it is unknown if they act in common disease pathways. Here we show that two disease-associated proteins, CSPα and the depalmitoylating enzyme palmitoyl-protein thioesterase 1 (PPT1/CLN1) are biochemically linked. We find that in DNAJC5/CLN4 patient brains, PPT1 is massively increased and mis-localized. Surprisingly, the specific enzymatic activity of PPT1 is dramatically reduced. Notably, we demonstrate that CSPα is depalmitoylated by PPT1 and hence its substrate. To determine the consequences of PPT1 accumulation, we compared the palmitomes from control and DNAJC5/CLN4 patient brains by quantitative proteomics. We discovered global changes in protein palmitoylation, mainly involving lysosomal and synaptic proteins. Our findings establish a functional link between two forms of NCL and serve as a springboard for investigations of NCL disease pathways.
Asunto(s)
Encéfalo/metabolismo , Proteínas del Choque Térmico HSP40/genética , Proteínas de la Membrana/genética , Mutación/genética , Lipofuscinosis Ceroideas Neuronales/genética , Lipofuscinosis Ceroideas Neuronales/patología , Tioléster Hidrolasas/metabolismo , Animales , Encéfalo/patología , Células Cultivadas , Corteza Cerebral/citología , Femenino , Proteínas del Choque Térmico HSP40/deficiencia , Humanos , Lipoilación/genética , Lipoilación/fisiología , Masculino , Proteínas de la Membrana/deficiencia , Ratones , Ratones Noqueados , Modelos Biológicos , Neuronas/efectos de los fármacos , Neuronas/metabolismo , Mapas de Interacción de Proteínas , Proteómica , Fracciones Subcelulares/metabolismo , Fracciones Subcelulares/patología , TransfecciónRESUMEN
Spinal muscular atrophy (SMA) is a neuromuscular disease caused by disruption of the survival motor neuron 1 (SMN1) gene, partly compensated for by the paralogous gene SMN2. Exon 7 inclusion is critical for full-length SMN protein production and occurs at a much lower frequency for SMN2 than for SMN1. Antisense oligonucleotide (ASO)-mediated blockade of an intron 7 splicing silencer was previously shown to promote inclusion of SMN2 exon 7 in SMA mouse models and mediate phenotypic rescue. However, downstream molecular consequences of this ASO therapy have not been defined. Here we characterize the gene-expression changes that occur in an induced model of SMA and show substantial rescue of those changes in central nervous system tissue upon intracerebroventricular administration of an ASO that promotes inclusion of exon 7, with earlier administration promoting greater rescue. This study offers a robust reference set of preclinical pharmacodynamic gene expression effects for comparison of other investigational therapies for SMA.
Asunto(s)
Exones , Expresión Génica , Atrofia Muscular Espinal/genética , Oligonucleótidos Antisentido/farmacología , Animales , Modelos Animales de Enfermedad , Expresión Génica/efectos de los fármacos , Ratones , Atrofia Muscular Espinal/tratamiento farmacológico , Médula Espinal/efectos de los fármacos , Médula Espinal/metabolismo , Proteína 2 para la Supervivencia de la Neurona Motora/efectos de los fármacos , Proteína 2 para la Supervivencia de la Neurona Motora/genéticaRESUMEN
Kufs disease, an adult-onset neuronal ceroid lipofuscinosis, is challenging to diagnose and genetically heterogeneous. Mutations in CLN6 were recently identified in recessive Kufs disease presenting as progressive myoclonus epilepsy (Type A), whereas the molecular basis of cases presenting with dementia and motor features (Type B) is unknown. We performed genome-wide linkage mapping of two families with recessive Type B Kufs disease and identified a single region on chromosome 11 to which both families showed linkage. Exome sequencing of five samples from the two families identified homozygous and compound heterozygous missense mutations in CTSF within this linkage region. We subsequently sequenced CTSF in 22 unrelated individuals with suspected recessive Kufs disease, and identified an additional patient with compound heterozygous mutations. CTSF encodes cathepsin F, a lysosomal cysteine protease, dysfunction of which is a highly plausible candidate mechanism for a storage disorder like ceroid lipofuscinosis. In silico modeling suggested the missense mutations would alter protein structure and function. Moreover, re-examination of a previously published mouse knockout of Ctsf shows that it recapitulates the light and electron-microscopic pathological features of Kufs disease. Although CTSF mutations account for a minority of cases of type B Kufs, CTSF screening should be considered in cases with early-onset dementia and may avoid the need for invasive biopsies.
Asunto(s)
Catepsina F/genética , Mutación Missense , Lipofuscinosis Ceroideas Neuronales/genética , Adulto , Animales , Células del Asta Anterior/patología , Estudios de Casos y Controles , Catepsina F/metabolismo , Mapeo Cromosómico , Consanguinidad , Análisis Mutacional de ADN , Exoma , Femenino , Estudios de Asociación Genética , Humanos , Escala de Lod , Ratones , Ratones Noqueados , Persona de Mediana Edad , Modelos Moleculares , Lipofuscinosis Ceroideas Neuronales/enzimología , Lipofuscinosis Ceroideas Neuronales/patología , Linaje , Estructura Secundaria de Proteína , Estructura Terciaria de Proteína , Análisis de Secuencia de ARNRESUMEN
Neuronal ceroid lipofuscinosis (NCL) is a genetically heterogeneous group of lysosomal diseases that collectively compose the most common Mendelian form of childhood-onset neurodegeneration. It is estimated that â¼8% of individuals diagnosed with NCL by conservative clinical and histopathologic criteria have been ruled out for mutations in the nine known NCL-associated genes, suggesting that additional genes remain unidentified. To further understand the genetic underpinnings of the NCLs, we performed whole-exome sequencing on DNA samples from a Mexican family affected by a molecularly undefined form of NCL characterized by infantile-onset progressive myoclonic epilepsy (PME), vision loss, cognitive and motor regression, premature death, and prominent NCL-type storage material. Using a recessive model to filter the identified variants, we found a single homozygous variant, c.550C>T in KCTD7, that causes a p.Arg184Cys missense change in potassium channel tetramerization domain-containing protein 7 (KCTD7) in the affected individuals. The mutation was predicted to be deleterious and was absent in over 6,000 controls. The identified variant altered the localization pattern of KCTD7 and abrogated interaction with cullin-3, a ubiquitin-ligase component and known KCTD7 interactor. Intriguingly, murine cerebellar cells derived from a juvenile NCL model (CLN3) showed enrichment of endogenous KCTD7. Whereas KCTD7 mutations have previously been linked to PME without lysosomal storage, this study clearly demonstrates that KCTD7 mutations also cause a rare, infantile-onset NCL subtype designated as CLN14.
Asunto(s)
Mutación , Lipofuscinosis Ceroideas Neuronales/genética , Canales de Potasio/genética , Animales , Preescolar , Femenino , Células HEK293 , Humanos , Lactante , Masculino , Ratones , Ratones Endogámicos C57BL , Linaje , Complejo de la Endopetidasa Proteasomal/genética , Ubiquitina/genéticaRESUMEN
We performed hypothesis-free linkage analysis and exome sequencing in a family with two siblings who had neuronal ceroid lipofuscinosis (NCL). Two linkage peaks with maximum LOD scores of 3.07 and 2.97 were found on chromosomes 7 and 17, respectively. Unexpectedly, we found these siblings to be homozygous for a c.813_816del (p.Thr272Serfs∗10) mutation in the progranulin gene (GRN, granulin precursor) in the latter peak. Heterozygous mutations in GRN are a major cause of frontotemporal lobar degeneration with TDP-43 inclusions (FTLD-TDP), the second most common early-onset dementia. Reexamination of progranulin-deficient mice revealed rectilinear profiles typical of NCL. The age-at-onset and neuropathology of FTLD-TDP and NCL are markedly different. Our findings reveal an unanticipated link between a rare and a common neurological disorder and illustrate pleiotropic effects of a mutation in the heterozygous or homozygous states.
Asunto(s)
Péptidos y Proteínas de Señalización Intercelular/genética , Mutación , Animales , Mapeo Cromosómico , Análisis Mutacional de ADN , Demencia/genética , Salud de la Familia , Femenino , Ligamiento Genético , Heterocigoto , Homocigoto , Humanos , Escala de Lod , Masculino , Ratones , Linaje , Fenotipo , ProgranulinasRESUMEN
BACKGROUND: Spinal muscular atrophy (SMA) is a motor neuron disorder caused by the absence of a functional survival of motor neuron 1, telomeric (SMN1) gene. Type I SMA, a lethal disease of infancy, accounts for the majority of cases. Newborn blood spot screening (NBS) to detect severe combined immunodeficiency (SCID) has been implemented in public health laboratories in the last 5 years. SCID detection is based on real-time PCR assays to measure T-cell receptor excision circles (TREC), a byproduct of T-cell development. We modified a multiplexed real-time PCR TREC assay to simultaneously determine the presence or absence of the SMN1 gene from a dried blood spot (DBS) punch in a single reaction well. METHOD: An SMN1 assay using a locked nucleic acid probe was initially developed with cell culture and umbilical cord blood (UCB) DNA extracts, and then integrated into the TREC assay. DBS punches were placed in 96-well arrays, washed, and amplified directly using reagents specific for TREC, a reference gene [ribonuclease P/MRP 30kDa subunit (RPP30)], and the SMN1 gene. The assay was tested on DBS made from UCB units and from peripheral blood samples of SMA-affected individuals and their family members. RESULTS: DBS made from SMA-affected individuals showed no SMN1-specific amplification, whereas DBS made from all unaffected carriers and UCB showed SMN1 amplification above a well-defined threshold. TREC and RPP30 content in all DBS were within the age-adjusted expected range. CONCLUSIONS: SMA caused by the absence of SMN1 can be detected from the same DBS punch used to screen newborns for SCID.
Asunto(s)
ADN/genética , Pruebas con Sangre Seca/métodos , Atrofia Muscular Espinal/diagnóstico , Reacción en Cadena en Tiempo Real de la Polimerasa/métodos , Receptores de Antígenos de Linfocitos T/genética , Inmunodeficiencia Combinada Grave/diagnóstico , Proteína 1 para la Supervivencia de la Neurona Motora/genética , Adolescente , Adulto , Niño , Preescolar , ADN/sangre , Pruebas Genéticas/métodos , Humanos , Lactante , Recién Nacido , Persona de Mediana Edad , Atrofia Muscular Espinal/sangre , Atrofia Muscular Espinal/genética , Inmunodeficiencia Combinada Grave/sangre , Inmunodeficiencia Combinada Grave/genética , Proteína 1 para la Supervivencia de la Neurona Motora/sangre , Adulto JovenRESUMEN
Autosomal-dominant adult-onset neuronal ceroid lipofuscinosis (ANCL) is characterized by accumulation of autofluorescent storage material in neural tissues and neurodegeneration and has an age of onset in the third decade of life or later. The genetic and molecular basis of the disease has remained unknown for many years. We carried out linkage mapping, gene-expression analysis, exome sequencing, and candidate-gene sequencing in affected individuals from 20 families and/or individuals with simplex cases; we identified in five individuals one of two disease-causing mutations, c.346_348delCTC and c.344T>G, in DNAJC5 encoding cysteine-string protein alpha (CSPα). These mutations-causing a deletion, p.Leu116del, and an amino acid exchange, p.Leu115Arg, respectively-are located within the cysteine-string domain of the protein and affect both palmitoylation-dependent sorting and the amount of CSPα in neuronal cells. The resulting depletion of functional CSPα might cause in parallel the presynaptic dysfunction and the progressive neurodegeneration observed in affected individuals and lysosomal accumulation of misfolded and proteolysis-resistant proteins in the form of characteristic ceroid deposits in neurons. Our work represents an important step in the genetic dissection of a genetically heterogeneous group of ANCLs. It also confirms a neuroprotective role for CSPα in humans and demonstrates the need for detailed investigation of CSPα in the neuronal ceroid lipofuscinoses and other neurodegenerative diseases presenting with neuronal protein aggregation.
Asunto(s)
Genes Dominantes/genética , Proteínas del Choque Térmico HSP40/genética , Proteínas de la Membrana/genética , Mutación/genética , Lipofuscinosis Ceroideas Neuronales/epidemiología , Lipofuscinosis Ceroideas Neuronales/genética , Adulto , Edad de Inicio , Secuencia de Bases , Encéfalo/metabolismo , Encéfalo/patología , Encéfalo/ultraestructura , Segregación Cromosómica/genética , Exones/genética , Familia , Femenino , Dosificación de Gen/genética , Regulación de la Expresión Génica , Ligamiento Genético , Humanos , Lipoilación , Lisosomas/metabolismo , Lisosomas/ultraestructura , Masculino , Datos de Secuencia Molecular , Lipofuscinosis Ceroideas Neuronales/patología , Neuronas/metabolismo , Neuronas/patología , Neuronas/ultraestructura , Linaje , Transporte de Proteínas , Análisis de Secuencia de ADNRESUMEN
Neuronal ceroid lipofuscinosis (NCL), first clinically described in 1826 and pathologically defined in the 1960s, refers to a group of disorders mostly diagnosed in the childhood years that involve the accumulation of lysosomal storage material with characteristic ultrastructure and prominent neurodegenerative features including vision loss, seizures, motor and cognitive function deterioration, and often times, psychiatric disturbances. All NCL disorders evidence early morbidity and treatment options are limited to symptomatic and palliative care. While distinct genetic forms of NCL have long been recognized, recent genetic advances are considerably widening the NCL genotypic and phenotypic spectrum, highlighting significant overlap with other neurodegenerative diseases. This review will discuss these recent advances and the expanded potential for increased awareness and new research that will ultimately lead to effective treatments for NCL and related disorders.
Asunto(s)
Lipofuscinosis Ceroideas Neuronales/diagnóstico , Lipofuscinosis Ceroideas Neuronales/genética , Genotipo , Humanos , FenotipoRESUMEN
BACKGROUND: The neuronal ceroid lipofuscinoses (NCLs, or Batten disease) comprise the most common Mendelian form of childhood-onset neurodegeneration, but the functions of the known underlying gene products remain poorly understood. The clinical heterogeneity of these disorders may shed light on genetic interactors that modify disease onset and progression. CASE PRESENTATION: We describe a proband with congenital hypotonia and an atypical form of infantile-onset, biopsy-proven NCL. Pathologic and molecular work-up of this patient identified CLN5 mutations as well as a mutation-previously described as incompletely penetrant or a variant of unknown significance-in POLG1, a nuclear gene essential for maintenance of mitochondrial DNA (mtDNA) copy number. The congenital presentation of this patient is far earlier than that described for either CLN5 patients or affected carriers of the POLG1 variant (c.1550 G > T, p.Gly517Val). Assessment of relative mtDNA copy number and mitochondrial membrane potential in the proband and control subjects suggested a pathogenic effect of the POLG1 change as well as a possible functional interaction with CLN5 mutations. CONCLUSIONS: These findings suggest that an incompletely penetrant variant in POLG1 may modify the clinical phenotype in a case of CLN5 and are consistent with emerging evidence of interactions between NCL-related genes and mitochondrial physiology.
Asunto(s)
ADN Polimerasa Dirigida por ADN/genética , Lipofuscinosis Ceroideas Neuronales/genética , Hibridación Genómica Comparativa , ADN Polimerasa gamma , ADN Mitocondrial/metabolismo , Heterocigoto , Humanos , Recién Nacido , Proteínas de Membrana de los Lisosomas , Imagen por Resonancia Magnética , Potencial de la Membrana Mitocondrial , Proteínas de la Membrana/genética , Lipofuscinosis Ceroideas Neuronales/patología , Fosforilación Oxidativa , Fenotipo , Análisis de Secuencia de ADNRESUMEN
SOD1, ANG, TARDBP and FUS mutations have been associated with amyotrophic lateral sclerosis (ALS). Our goal was to extend molecular genetic analysis to newly identified ALS genetic loci and to determine the frequency of mutations, distribution of disease genes, and variant spectrum of these genes in a large United States ALS-phenotype cohort. We screened 1220 probands with an ALS phenotype, referred originally for SOD1 molecular genetic analysis. 1128 SOD1-negative probands were screened for ANG, and 277 and 223 SOD1- and ANG-negative samples were screened for TARDBP and FUS, respectively. One hundred additional probands were specifically screened only for FUS exon 15. We identified a total of 36 different SOD1 mutations, including three novel mutations, in 92 probands. ANG screening identified three mutations, including two novel mutations, and TARDBP screening identified two previously reported TARDBP mutations. We also identified four mutations in FUS, including the reported FUS in-frame deletion, c.430_447del, p.Gly144_Tyr149del, in a patient with inclusion body myositis, and two known FUS missense mutations. From this study, we estimate frequencies for SOD1, ANG, TARDBP and FUS mutations, in this United States cohort, to be 7.5%, 0.71%, 0.72% and 1.9%, respectively. In conclusion, we identify novel variants in SOD1, ANG, TARDBP and FUS, and expand the FUS-associated clinicopathologic phenotype.
Asunto(s)
Esclerosis Amiotrófica Lateral/genética , Técnicas de Laboratorio Clínico , Proteínas de Unión al ADN/genética , Proteína FUS de Unión a ARN/genética , Ribonucleasa Pancreática/genética , Superóxido Dismutasa/genética , Esclerosis Amiotrófica Lateral/fisiopatología , Predisposición Genética a la Enfermedad , Pruebas Genéticas , Humanos , Mutación , Fenotipo , Superóxido Dismutasa-1 , Estados UnidosRESUMEN
INTRODUCTION: Norrie disease is a rare X-linked congenital retinal vasculopathy that may be accompanied by sensorineural deafness, mental retardation, and other neurological deficits. Here we present a family in which Norrie disease co-segregated with either early-onset idiopathic pulmonary hypertension or sudden death preceded by a period of progressive dyspnea. Neither Norrie disease, nor its atypical variants described to date, have been associated with this extended clinical phenotype. METHODS AND RESULTS: Molecular analysis of the Norrie disease gene (NDP) and adjacent loci was performed by multiplex ligation-dependent probe amplification and comparative genomic hybridisation. Affected males in this family showed an inherited hemizygous deletion restricted to NDP and two immediately telomeric genes, monoamine oxidase-B (MAO-B) and monoamine oxidase-A (MAO-A), which encode closely related enzymes that metabolize biogenic amines including serotonin, dopamine, and norepinephrine. Sequencing of the deletion junction showed an unusual pattern in which a region of microhomology flanked intervening genomic sequence. CONCLUSION: Because abnormalities of biogenic amines, particularly serotonin, have been implicated in the pathophysiology of pulmonary hypertension, we propose that presumed MAO deficiency in these patients may represent a novel risk factor for pulmonary hypertension, particularly forms with very early onset. Fine-mapping of other microdeletions at this locus may provide insights into additional mechanisms for nonrecurrent genomic rearrangements at this and other chromosomal loci.
Asunto(s)
Cromosomas Humanos X/genética , Proteínas del Ojo/genética , Hipertensión Pulmonar/genética , Proteínas del Tejido Nervioso/genética , Secuencia de Bases , Ceguera/congénito , Ceguera/genética , Niño , Deleción Cromosómica , Análisis Mutacional de ADN , Salud de la Familia , Resultado Fatal , Femenino , Enfermedades Genéticas Ligadas al Cromosoma X , Humanos , Lactante , Masculino , Enfermedades del Sistema Nervioso/genética , Linaje , Degeneración Retiniana , Espasmos Infantiles/genéticaRESUMEN
Despite newly available treatments for spinal muscular atrophy (SMA), novel circulating biomarkers are still critically necessary to track SMA progression and therapeutic response. To identify potential biomarkers, we performed whole-blood RNA sequencing analysis in SMA type 1 subjects under 1 year old and age-matched healthy controls. Our analysis revealed the Heat Shock Protein Family A Member 7 (HSPA7)/heat shock 70kDa protein 7 (HSP70B) as a novel candidate biomarker to track SMA progression early in life. Changes in circulating HSP70B protein levels were associated with changes in circulating neurofilament levels in SMA newborns and infants. Future studies will determine whether HSP70B levels respond to molecular therapies.
Asunto(s)
Proteínas HSP70 de Choque Térmico/sangre , Atrofia Muscular Espinal/sangre , Atrofia Muscular Espinal/diagnóstico , Biomarcadores/sangre , Estudios de Cohortes , Femenino , Humanos , Lactante , Recién Nacido , Estudios Longitudinales , MasculinoRESUMEN
Dysregulation of genes that control cell-cycle progression and DNA repair is a hallmark of tumorigenesis. It is becoming increasingly apparent, however, that these defects also contribute to degeneration of post-mitotic neurons under certain conditions. The gene for ataxia-telangiectasia mutated (ATM) is a prototype for this dual mechanism of action, with loss-of-function mutations causing not only selective degeneration of cerebellar neurons but also increased susceptibility to breast cancer and hematologic malignancy. Increased dosage of amyloid precursor protein in Down syndrome (trisomy 21) predisposes to dementia of Alzheimer type and may also contribute to acute leukemia and transient myeloproliferative disorder. The gene parkin, loss-of-function mutations in which account for about half of cases of early-onset Parkinson disease, has been identified as a candidate tumor suppressor gene by several groups. Parkin is deleted or downregulated in several tumor types, and its re-expression sensitizes derivative cell lines to inhibitors of cell-cycle progression. The overlap of molecular pathways implicated in cancer and neurodegeneration challenges long-held notions about differentiated cellular states and may open the door to novel therapeutic approaches to both groups of disorders.
Asunto(s)
Reparación del ADN , Regulación Neoplásica de la Expresión Génica , Neoplasias/patología , Enfermedades Neurodegenerativas/patología , Amiloide/metabolismo , Animales , Proteínas de la Ataxia Telangiectasia Mutada , Biomarcadores/metabolismo , Ciclo Celular , Proteínas de Ciclo Celular/metabolismo , Proteínas de Unión al ADN/metabolismo , Síndrome de Down/genética , Síndrome de Down/patología , Humanos , Modelos Biológicos , Mutación , Neoplasias/metabolismo , Enfermedades Neurodegenerativas/metabolismo , Neuronas/metabolismo , Enfermedad de Parkinson/genética , Enfermedad de Parkinson/patología , Proteínas Serina-Treonina Quinasas/metabolismo , Proteínas Supresoras de Tumor/metabolismoRESUMEN
BACKGROUND: Spinal muscular atrophy (SMA) is an autosomal recessive neuromuscular disorder caused by homozygous survival of motor neuron 1 (SMN1) gene disruption. Despite a genetic etiology, little is known about subtype concordance among siblings. OBJECTIVE: To investigate subtype concordance among siblings with SMA. METHODS: Cure SMA maintains a database of newly diagnosed patients with SMA, which was utilized for this research. RESULTS: Among 303 sibships identified between 1996 and 2016, 84.8% were subtype concordant. Of concordant sibships, subtype distribution was as follows: Type I, 54.5%; Type II, 31.9%; Type III, 13.2%; Type IV, 0.4%. Subtype and concordance/discordance association was significant (Fisher's exact test; pâ<â0.0001). Among discordant sibships (chi-square test, pâ<â0.0001), Types II/III (52.2%) and Types I/II (28.3%) were the most common pairs. No association was found between sibling sex and concordance. Our findings show that most siblings with SMA shared the same subtype concordance (most commonly Type I). CONCLUSIONS: These data are valuable for understanding familial occurrence of SMA subtypes, enabling better individual treatment and management planning in view of new treatment options and newborn screening initiatives.
Asunto(s)
Atrofia Muscular Espinal , Hermanos , Bases de Datos Factuales , Femenino , Humanos , Lactante , Masculino , Atrofia Muscular Espinal/clasificación , Atrofia Muscular Espinal/epidemiología , Atrofia Muscular Espinal/genética , Atrofia Muscular Espinal/fisiopatología , FenotipoRESUMEN
OBJECTIVE: To evaluate plasma phosphorylated neurofilament heavy chain (pNF-H) as a biomarker in spinal muscular atrophy (SMA). METHODS: Levels of pNF-H were measured using the ProteinSimple® platform in plasma samples from infants with SMA enrolled in ENDEAR (NCT02193074) and infants/children without neurological disease. RESULTS: Median pNF-H plasma level was 167.0 pg/mL (7.46-7,030; n = 34) in children without SMA (aged 7 weeks-18 years) and was higher in those aged < 1 versus 1-18 years (P = 0.0002). In ENDEAR participants with infantile-onset SMA, median baseline pNF-H level (15,400 pg/mL; 2390-50,100; n = 117) was ~10-fold higher than that of age-matched infants without SMA (P < 0.0001) and ~90-fold higher than children without SMA (P < 0.0001). Higher pretreatment pNF-H levels in infants with SMA were associated with younger age at symptom onset, diagnosis, and first dose; lower baseline Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders score; and lower peroneal compound muscle potential amplitude. Nusinersen treatment was associated with a rapid and greater decline in pNF-H levels: nusinersen-treated infants experienced a steep 71.9% decline at 2 months to 90.1% decline at 10 months; sham control-treated infants declined steadily by 16.2% at 2 months and 60.3% at 10 months. INTERPRETATION: Plasma pNF-H levels are elevated in infants with SMA. Levels inversely correlate with age at first dose and several markers of disease severity. Nusinersen treatment is associated with a significant decline in pNF-H levels followed by relative stabilization. Together these data suggest plasma pNF-H is a promising marker of disease activity/treatment response in infants with SMA.
Asunto(s)
Filamentos Intermedios/metabolismo , Atrofia Muscular Espinal/metabolismo , Adolescente , Biomarcadores/sangre , Niño , Método Doble Ciego , Femenino , Humanos , Masculino , Atrofia Muscular Espinal/sangreRESUMEN
Spinal muscular atrophy (SMA) is a neurodegenerative disease associated with severe muscle atrophy and weakness in the limbs and trunk. We report interim efficacy and safety outcomes as of March 29, 2019 in 25 children with genetically diagnosed SMA who first received nusinersen in infancy while presymptomatic in the ongoing Phase 2, multisite, open-label, single-arm NURTURE trial. Fifteen children have two SMN2 copies and 10 have three SMN2 copies. At last visit, children were median (range) 34.8 [25.7-45.4] months of age and past the expected age of symptom onset for SMA Types I or II; all were alive and none required tracheostomy or permanent ventilation. Four (16%) participants with two SMN2 copies utilized respiratory support for ≥6 h/day for ≥7 consecutive days that was initiated during acute, reversible illnesses. All 25 participants achieved the ability to sit without support, 23/25 (92%) achieved walking with assistance, and 22/25 (88%) achieved walking independently. Eight infants had adverse events considered possibly related to nusinersen by the study investigators. These results, representing a median 2.9 years of follow up, emphasize the importance of proactive treatment with nusinersen immediately after establishing the genetic diagnosis of SMA in presymptomatic infants and emerging newborn screening efforts.
Asunto(s)
Atrofia Muscular Espinal/terapia , Oligonucleótidos/administración & dosificación , Preescolar , Femenino , Estudios de Seguimiento , Humanos , Lactante , Recién Nacido , Masculino , Actividad Motora , Atrofia Muscular Espinal/genética , Atrofia Muscular Espinal/fisiopatología , Oligonucleótidos/efectos adversos , Proteína 2 para la Supervivencia de la Neurona Motora/genética , Factores de Tiempo , Resultado del TratamientoRESUMEN
Mutations in parkin, which encodes a RING domain protein associated with ubiquitin ligase activity, lead to autosomal recessive Parkinson's disease characterized by midbrain dopamine neuron loss. Here we show that parkin functions in a multiprotein ubiquitin ligase complex that includes the F-box/WD repeat protein hSel-10 and Cullin-1. HSel-10 serves to target the parkin ubiquitin ligase activity to cyclin E, an hSel-10-interacting protein previously implicated in the regulation of neuronal apoptosis. Consistent with the notion that cyclin E is a substrate of the parkin ubiquitin ligase complex, parkin deficiency potentiates the accumulation of cyclin E in cultured postmitotic neurons exposed to the glutamatergic excitotoxin kainate and promotes their apoptosis. Furthermore, parkin overexpression attenuates the accumulation of cyclin E in toxin-treated primary neurons, including midbrain dopamine neurons, and protects them from apoptosis.
Asunto(s)
Ácido Kaínico/toxicidad , Ligasas/biosíntesis , Mitosis/efectos de los fármacos , Mitosis/fisiología , Neuronas/efectos de los fármacos , Péptido Sintasas/biosíntesis , Ubiquitina-Proteína Ligasas , Animales , Apoptosis/efectos de los fármacos , Apoptosis/fisiología , Supervivencia Celular/efectos de los fármacos , Supervivencia Celular/fisiología , Células Cultivadas , Células HeLa , Humanos , Ligasas/genética , Ratones , Neuronas/citología , Neuronas/metabolismo , Péptido Sintasas/genética , Proteínas Ligasas SKP Cullina F-boxRESUMEN
Cord formation is a characteristic property of the cultured Mycobacterium tuberculosis complex species. We describe a case of Mycobacterium marinum demonstrating robust cord formation. Nontuberculous mycobacteria can form true cords in broth culture but do so rarely, despite the fact that many species contain the cell wall glycolipid that mediates cord formation.