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Pathogenic variants in the UBQLN2 gene cause X-linked dominant amyotrophic lateral sclerosis and/or frontotemporal dementia characterised by ubiquilin 2 aggregates in neurons of the motor cortex, hippocampus, and spinal cord. However, ubiquilin 2 neuropathology is also seen in sporadic and familial amyotrophic lateral sclerosis and/or frontotemporal dementia cases not caused by UBQLN2 pathogenic variants, particularly C9orf72-linked cases. This makes the mechanistic role of mutant ubiquilin 2 protein and the value of ubiquilin 2 pathology for predicting genotype unclear. Here we examine a cohort of 44 genotypically diverse amyotrophic lateral sclerosis cases with or without frontotemporal dementia, including eight cases with UBQLN2 variants (resulting in p.S222G, p.P497H, p.P506S, p.T487I (two cases), and p.P497L (three cases)). Using multiplexed (5-label) fluorescent immunohistochemistry, we mapped the co-localisation of ubiquilin 2 with phosphorylated TDP-43, dipeptide repeat aggregates, and p62, in the hippocampus of controls (n = 6), or amyotrophic lateral sclerosis with or without frontotemporal dementia in sporadic (n = 20), unknown familial (n = 3), SOD1-linked (n = 1), FUS-linked (n = 1), C9orf72-linked (n = 5), and UBQLN2-linked (n = 8) cases. We differentiate between i) ubiquilin 2 aggregation together with phosphorylated TDP-43 or dipeptide repeat proteins, and ii) ubiquilin 2 self-aggregation promoted by UBQLN2 pathogenic variants that cause amyotrophic lateral sclerosis/and frontotemporal dementia. Overall, we describe a hippocampal protein aggregation signature that fully distinguishes mutant from wildtype ubiquilin 2 in amyotrophic lateral sclerosis with or without frontotemporal dementia, whereby mutant ubiquilin 2 is more prone than wildtype to aggregate independently of driving factors. This neuropathological signature can be used to assess the pathogenicity of UBQLN2 gene variants and to understand the mechanisms of UBQLN2-linked disease.
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Superoxide dismutase (SOD1) gene variants may cause amyotrophic lateral sclerosis, some of which are associated with a distinct phenotype. Most studies assess limited variants or sample sizes. In this international, retrospective observational study, we compare phenotypic and demographic characteristics between people with SOD1-ALS and people with ALS and no recorded SOD1 variant. We investigate which variants are associated with age at symptom onset and time from onset to death or censoring using Cox proportional-hazards regression. The SOD1-ALS dataset reports age of onset for 1122 and disease duration for 883 people; the comparator population includes 10,214 and 9010 people respectively. Eight variants are associated with younger age of onset and distinct survival trajectories; a further eight associated with younger onset only and one with distinct survival only. Here we show that onset and survival are decoupled in SOD1-ALS. Future research should characterise rarer variants and molecular mechanisms causing the observed variability.
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Esclerosis Amiotrófica Lateral , Humanos , Superóxido Dismutasa-1/genética , Esclerosis Amiotrófica Lateral/genética , Esclerosis Amiotrófica Lateral/epidemiología , Superóxido Dismutasa/genética , Fenotipo , MutaciónRESUMEN
JAG2 encodes the Notch ligand Jagged2. The conserved Notch signaling pathway contributes to the development and homeostasis of multiple tissues, including skeletal muscle. We studied an international cohort of 23 individuals with genetically unsolved muscular dystrophy from 13 unrelated families. Whole-exome sequencing identified rare homozygous or compound heterozygous JAG2 variants in all 13 families. The identified bi-allelic variants include 10 missense variants that disrupt highly conserved amino acids, a nonsense variant, two frameshift variants, an in-frame deletion, and a microdeletion encompassing JAG2. Onset of muscle weakness occurred from infancy to young adulthood. Serum creatine kinase (CK) levels were normal or mildly elevated. Muscle histology was primarily dystrophic. MRI of the lower extremities revealed a distinct, slightly asymmetric pattern of muscle involvement with cores of preserved and affected muscles in quadriceps and tibialis anterior, in some cases resembling patterns seen in POGLUT1-associated muscular dystrophy. Transcriptome analysis of muscle tissue from two participants suggested misregulation of genes involved in myogenesis, including PAX7. In complementary studies, Jag2 downregulation in murine myoblasts led to downregulation of multiple components of the Notch pathway, including Megf10. Investigations in Drosophila suggested an interaction between Serrate and Drpr, the fly orthologs of JAG1/JAG2 and MEGF10, respectively. In silico analysis predicted that many Jagged2 missense variants are associated with structural changes and protein misfolding. In summary, we describe a muscular dystrophy associated with pathogenic variants in JAG2 and evidence suggests a disease mechanism related to Notch pathway dysfunction.
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Proteína Jagged-2/genética , Distrofias Musculares/genética , Adolescente , Adulto , Secuencia de Aminoácidos , Animales , Línea Celular , Niño , Preescolar , Proteínas de Drosophila/genética , Drosophila melanogaster/genética , Femenino , Glucosiltransferasas/genética , Haplotipos/genética , Humanos , Proteína Jagged-1/genética , Proteína Jagged-2/química , Proteína Jagged-2/deficiencia , Proteína Jagged-2/metabolismo , Masculino , Proteínas de la Membrana/genética , Ratones , Persona de Mediana Edad , Modelos Moleculares , Músculos/metabolismo , Músculos/patología , Distrofias Musculares/patología , Mioblastos/metabolismo , Mioblastos/patología , Linaje , Fenotipo , Receptores Notch/metabolismo , Transducción de Señal , Secuenciación del Exoma , Adulto JovenRESUMEN
CRISPR/Cas9-mediated genome editing provides potential for therapeutic development. Efficacy and long-term safety represent major concerns that remain to be adequately addressed in preclinical studies. Here we show that CRISPR/Cas9-mediated genome editing in two distinct SOD1-amyotrophic lateral sclerosis (ALS) transgenic mouse models prevented the development of ALS-like disease and pathology. The disease-linked transgene was effectively edited, with rare off-target editing events. We observed frequent large DNA deletions, ranging from a few hundred to several thousand base pairs. We determined that these large deletions were mediated by proximate identical sequences in Alu elements. No evidence of other diseases was observed beyond 2 years of age in these genome edited mice. Our data provide preclinical evidence of the efficacy and long-term safety of the CRISPR/Cas9 therapeutic approach. Moreover, the molecular mechanism of proximate identical sequences-mediated recombination provides mechanistic information to optimize therapeutic targeting design, and to avoid or minimize unintended and potentially deleterious recombination events.
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Esclerosis Amiotrófica Lateral/genética , Sistemas CRISPR-Cas/genética , Edición Génica/estadística & datos numéricos , Superóxido Dismutasa-1/genética , Secuencia de Aminoácidos , Animales , Modelos Animales de Enfermedad , Ratones , Ratones Transgénicos , Superóxido Dismutasa-1/química , Superóxido Dismutasa-1/metabolismoRESUMEN
Mutations in coiled-coil-helix-coiled-coil-helix domain containing 10 (CHCHD10) have been identified in patients suffering from various degenerative diseases including mitochondrial myopathy, spinal muscular atrophy Jokela type, frontotemporal dementia, and/or amyotrophic lateral sclerosis (ALS). The pathogenic mechanism underlying CHCHD10-linked divergent disorders remains largely unknown. Here we show that transgenic mice overexpressing an ALS-linked CHCHD10 p.R15L mutation leads to an abbreviated lifespan compared with CHCHD10-WT transgenic mice. The occurrence and severity of the phenotype correlates to transgene copy number. Central nervous system (CNS), skeletal muscle, and cardiac pathology is apparent in CHCHD10-R15L transgenic mice. Despite the pathology, CHCHD10-R15L transgenic mice perform comparably to control mice in motor behavioral tasks until very close to death. Although paralysis is not observed, these models provide insight into the pleiotropic nature of CHCHD10 and suggest a contribution of CNS, skeletal muscle, and cardiac pathology to CHCHD10 p.R15L-ALS pathogenesis.
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OBJECTIVE: To test the hypothesis that autologous nonmyeloablative hematopoietic stem cell transplantation (HSCT) is safe and shows efficacy in the treatment of stiff-person spectrum disorder (SPSD). METHODS: Twenty-three participants were treated in a prospective open-label cohort study of safety and efficacy. After stem cell mobilization with cyclophosphamide (2 g/m2) and filgrastim (5-10 µg/kg/d), participants were treated with cyclophosphamide (200 mg/kg) divided as 50 mg/kg IV on day -5 to day -2; rabbit anti-thymocyte globulin (thymoglobulin) given intravenously at 0.5 mg/kg on day -5, 1 mg/kg on days -4 and -3, and 1.5 mg/kg on days -2, and -1 (total dose 5.5 mg/kg); and rituximab 500 mg IV on days -6 and +1. Unselected peripheral blood stem cells were infused on day 0. Safety was assessed by survival and National Cancer Institute common toxicity criteria for adverse events during HSCT. Outcome was assessed by ≥50% decrease or discontinuation of antispasmodic drugs and by quality of life instruments. RESULTS: There was no treatment-related mortality. One participant died 1 year after transplantation of disease progression. Of the 74% of participants who responded, 47% have stayed in remission for a mean of 3.5 years; 26% did not respond. Compared to nonresponders, responders were more likely to have pretransplantation intermittent muscle spasms (16 of 17 vs 0 of 6), normal reflexes (12 of 17 vs 0 of 6), and positive CSF anti-glutamic acid decarboxylase serology (12 of 14 vs 2 of 6). Compared to responders, nonresponders were more likely to have lead pipe rigidity (4 of 6 vs 0 of 17) and EMG-documented simultaneous contraction of agonist/antagonist limb muscles (4 of 6 vs 1 of 17). Pre-HSCT use of prescription serotonin selective receptor inhibitor (SSRI) or serotonin and norepinephrine reuptake inhibitor (SNRI) was more common in those who relapsed or never responded (9 of 12) compared to those responders who never relapsed (0 of 11). CONCLUSION: In this cohort, HSCT was safe, but the beneficial effect of HSCT was variable and confined predominately to participants with episodic spasms and normal tendon reflexes without simultaneous cocontraction of limb agonist/antagonist muscles who were not taking SSRI or SNRI antidepressants. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that, for a subset of people with SPSD, autologous nonmyeloablative HSCT improves outcomes. CLINICALTRIALSGOV IDENTIFIER: NCT02282514.
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Trasplante de Células Madre Hematopoyéticas , Inmunosupresores/administración & dosificación , Evaluación de Resultado en la Atención de Salud , Síndrome de la Persona Rígida/fisiopatología , Síndrome de la Persona Rígida/terapia , Adulto , Femenino , Estudios de Seguimiento , Trasplante de Células Madre Hematopoyéticas/efectos adversos , Humanos , Masculino , Persona de Mediana Edad , Síndrome de la Persona Rígida/tratamiento farmacológico , Trasplante AutólogoRESUMEN
The genetic underpinnings of late-onset degenerative disease have typically been determined by screening families for the segregation of genetic variants with the disease trait in affected, but not unaffected, individuals. However, instances of intrafamilial etiological heterogeneity, where pathogenic variants in a culprit gene are not shared among all affected family members, continue to emerge and confound gene-discovery and genetic counselling efforts. Discordant intrafamilial cases lacking a mutation shared by other affected family members are described as disease phenocopies. This description often results in an over-simplified acceptance of an environmental cause of disease in the phenocopy cases, while the role of intrafamilial genetic heterogeneity, shared de novo mutations or epigenetic aberrations in such families is often ignored. On a related note, it is now evident that the same disease-associated variant can be present in individuals exhibiting clinically distinct phenotypes, thereby genetically uniting seemingly unrelated syndromes to form a spectrum of disease. Herein, we discuss the intricacies of determining complex degenerative disease aetiology and suggest alternative mechanisms of disease transmission that may account for the apparent missing heritability of disease.
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OBJECTIVE: To test the hypothesis that rs573116164 will have disease-modifying effects in patients with superoxide dismutase 1 (SOD1) familial amyotrophic lateral sclerosis (fALS), we characterized rs573116164 within a cohort of 190 patients with fALS and 560 healthy age-matched controls to assess the variant for association with various measures of disease. METHODS: Using a previously described bioinformatics evaluation algorithm, a polymorphic short structural variant associated with SOD1 was identified according to its theoretical effect on gene expression. An 12-18 poly-T repeat (rs573116164) within the 3' untranslated region of serine and arginine rich proteins-related carboxy terminal domain associated factor 4 (SCAF4), a gene that is adjacent to SOD1, was assessed for disease association and influence on survival and age at onset in an fALS cohort using PCR, Sanger sequencing, and capillary separation techniques for allele detection. RESULTS: In a North American cohort of predominantly SOD1 fALS patients (n =190) and age-matched healthy controls (n = 560), we showed that carriage of an 18T SCAF4 allele was associated with disease within this cohort (odds ratio [OR] 6.6; 95% confidence interval [CI] 3.9-11.2; p = 4.0e-11), but also within non-SOD1 cases (n = 27; OR 5.3; 95% CI 1.9-14.5; p = 0.0014). This finding suggests genetically SOD1-independent effects of SCAF4 on fALS susceptibility. Furthermore, carriage of an 18T allele was associated with a 26-month reduction in survival time (95% CI 6.6-40.8; p = 0.014), but did not affect age at onset of disease. CONCLUSIONS: The findings in this fALS cohort suggest that rs573116164 could have SOD1-independent and broader relevance in ALS, warranting further investigation in other fALS and sporadic ALS cohorts, as well as studies of functional effects of the 18T variant on gene expression.
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Mutations in UBQLN2 cause amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), and other neurodegenerations. However, the mechanism by which the UBQLN2 mutations cause disease remains unclear. Alterations in proteins involved in autophagy are prominent in neuronal tissue of human ALS UBQLN2 patients and in a transgenic P497S UBQLN2 mouse model of ALS/FTD, suggesting a pathogenic link. Here, we show UBQLN2 functions in autophagy and that ALS/FTD mutant proteins compromise this function. Inactivation of UBQLN2 expression in HeLa cells reduced autophagic flux and autophagosome acidification. The defect in acidification was rescued by reexpression of wild type (WT) UBQLN2 but not by any of the five different UBQLN2 ALS/FTD mutants tested. Proteomic analysis and immunoblot studies revealed P497S mutant mice and UBQLN2 knockout HeLa and NSC34 cells have reduced expression of ATP6v1g1, a critical subunit of the vacuolar ATPase (V-ATPase) pump. Knockout of UBQLN2 expression in HeLa cells decreased turnover of ATP6v1g1, while overexpression of WT UBQLN2 increased biogenesis of ATP6v1g1 compared with P497S mutant UBQLN2 protein. In vitro interaction studies showed that ATP6v1g1 binds more strongly to WT UBQLN2 than to ALS/FTD mutant UBQLN2 proteins. Intriguingly, overexpression of ATP6v1g1 in UBQLN2 knockout HeLa cells increased autophagosome acidification, suggesting a therapeutic approach to overcome the acidification defect. Taken together, our findings suggest that UBQLN2 mutations drive pathogenesis through a dominant-negative loss-of-function mechanism in autophagy and that UBQLN2 functions as an important regulator of the expression and stability of ATP6v1g1. These findings may have important implications for devising therapies to treat UBQLN2-linked ALS/FTD.
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Proteínas Adaptadoras Transductoras de Señales/metabolismo , Esclerosis Amiotrófica Lateral/genética , Autofagosomas/fisiología , Proteínas Relacionadas con la Autofagia/metabolismo , Autofagia/genética , Demencia/genética , Proteínas Adaptadoras Transductoras de Señales/genética , Esclerosis Amiotrófica Lateral/metabolismo , Esclerosis Amiotrófica Lateral/patología , Animales , Proteínas Relacionadas con la Autofagia/genética , Biomarcadores/metabolismo , Línea Celular , Demencia/metabolismo , Demencia/patología , Predisposición Genética a la Enfermedad , Humanos , Concentración de Iones de Hidrógeno , Proteínas de Membrana de los Lisosomas/genética , Proteínas de Membrana de los Lisosomas/metabolismo , Ratones , Ratones Transgénicos , Proteínas Asociadas a Microtúbulos/genética , Proteínas Asociadas a Microtúbulos/metabolismo , Mutación , Unión Proteica , Proteína Sequestosoma-1/genética , Proteína Sequestosoma-1/metabolismo , Regulación hacia Arriba , ATPasas de Translocación de Protón Vacuolares/genética , ATPasas de Translocación de Protón Vacuolares/metabolismoRESUMEN
OBJECTIVE: As structural variations may underpin susceptibility to complex neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS), the objective of this study was to investigate a structural variant (SV) within sequestosome 1 (SQSTM1). METHODS: A candidate insertion/deletion variant within intron 5 of the SQSTM1 gene was identified using a previously established SV evaluation algorithm and chosen according to its subsequent theoretical effect on gene expression. The variant was systematically assessed through PCR, polyacrylamide gel fractionation, Sanger sequencing, and reverse transcriptase PCR. RESULTS: A reliable and robust assay confirmed the polymorphic nature of this variant and that the variant may influence SQSTM1 transcript levels. In a North American cohort of patients with familial ALS (fALS) and sporadic ALS (sALS) (n = 403) and age-matched healthy controls (n = 562), we subsequently showed that the SQSTM1 variant is associated with fALS (p = 0.0036), particularly in familial superoxide dismutase 1 mutation positive patients (p = 0.0005), but not with patients with sALS (p = 0.97). CONCLUSIONS: This disease association highlights the importance and implications of further investigation into SVs that may provide new targets for cohort stratification and therapeutic development.
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The most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) is a hexanucleotide repeat expansion in C9orf72 (C9-HRE). While RNA and dipeptide repeats produced by C9-HRE disrupt nucleocytoplasmic transport, the proteins that become redistributed remain unknown. Here, we utilized subcellular fractionation coupled with tandem mass spectrometry and identified 126 proteins, enriched for protein translation and RNA metabolism pathways, which collectively drive a shift toward a more cytosolic proteome in C9-HRE cells. Among these was eRF1, which regulates translation termination and nonsense-mediated decay (NMD). eRF1 accumulates within elaborate nuclear envelope invaginations in patient induced pluripotent stem cell (iPSC) neurons and postmortem tissue and mediates a protective shift from protein translation to NMD-dependent mRNA degradation. Overexpression of eRF1 and the NMD driver UPF1 ameliorate C9-HRE toxicity in vivo. Our findings provide a resource for proteome-wide nucleocytoplasmic alterations across neurodegeneration-associated repeat expansion mutations and highlight eRF1 and NMD as therapeutic targets in C9orf72-associated ALS and/or FTD.
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Esclerosis Amiotrófica Lateral/genética , Proteína C9orf72/genética , Proteínas de Drosophila/genética , Demencia Frontotemporal/genética , Neuronas/metabolismo , Degradación de ARNm Mediada por Codón sin Sentido/genética , Factores de Terminación de Péptidos/genética , ARN Mensajero/metabolismo , Esclerosis Amiotrófica Lateral/metabolismo , Animales , Proteína C9orf72/metabolismo , Fraccionamiento Celular , Proteínas de Drosophila/metabolismo , Drosophila melanogaster , Demencia Frontotemporal/metabolismo , Células HEK293 , Humanos , Células Madre Pluripotentes Inducidas , Membrana Nuclear , Terminación de la Cadena Péptídica Traduccional/genética , Factores de Terminación de Péptidos/metabolismo , Biosíntesis de Proteínas , Proteoma , Fracciones Subcelulares , Espectrometría de Masas en TándemRESUMEN
With the exception of rare, juvenile-onset, autosomal recessive cases, primary lateral sclerosis (PLS) has long been considered an exclusively sporadic motor neuron disease. However, the identification of PLS cases within pedigrees with familial amyotrophic lateral sclerosis (ALS), together with the clinical and neuropathological overlap with other neurodegenerative disease with strong genetic component such as ALS and hereditary spastic paraparesis (HSP), suggest the existence of a genetic component in PLS as well. Here we will review the genetics of juvenile PLS-like syndromes and the contribution of mutations in ALS and HSP-associated genes to PLS pathogenesis.
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Esclerosis Amiotrófica Lateral , Enfermedad de la Neurona Motora , Enfermedades Neurodegenerativas , Paraplejía Espástica Hereditaria , Esclerosis Amiotrófica Lateral/genética , Humanos , LinajeRESUMEN
Mutations in TRPV4 are linked to a group of clinically distinct, but also overlapping axonal neuropathies, including Charcot-Marie-Tooth disease type 2C (CMT2C), scapuloperoneal spinal muscular atrophy, and congenital distal spinal muscular atrophy. The incidence of TRPV4-linked cases ranges from 0 to 7% in overall axonal neuropathy cohorts from European countries and Australia. However, the data from other areas remain largely unknown. In this study, we screened for TRPV4 mutations in a well-characterized USA cohort of 62 unrelated CMT2 patients without mutations in MFN2, GARS, NEFL, and GDAP1. All 15 coding exons of TRPV4 were analyzed by Sanger-sequencing. Clinical features of TRPV4-linked patients were compared with those lacking TRPV4 mutations. We identified two TRPV4 mutations in two patients. A TRPV4-R316C was identified in a patient with family history, while a TRPV4-R269C in an apparently sporadic case. Marked clinical variations were observed in the patients with TRPV4 mutations. Our data suggest that TRPV4-linked CMT2C accounts for a sizable fraction in this USA cohort of CMT2; it has a wide phenotypic spectrum, and vocal cord paralysis, scapular weakness and wasting, skeletal dysplasia, and hearing loss are suggestive signs for TRPV4-linked CMT2C.
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Enfermedad de Charcot-Marie-Tooth/epidemiología , Atrofia Muscular Espinal/epidemiología , Mutación , Canales Catiónicos TRPV/genética , Adulto , Axones/patología , Enfermedades del Desarrollo Óseo/etiología , Enfermedad de Charcot-Marie-Tooth/genética , Enfermedad de Charcot-Marie-Tooth/fisiopatología , Exones/genética , Femenino , Asesoramiento Genético , Pérdida Auditiva/etiología , Humanos , Incidencia , Masculino , Debilidad Muscular/etiología , Atrofia Muscular Espinal/genética , Atrofia Muscular Espinal/fisiopatología , Mutación Missense , Linaje , Fenotipo , Mutación Puntual , Canales Catiónicos TRPV/deficiencia , Estados Unidos/epidemiología , Parálisis de los Pliegues Vocales/etiologíaRESUMEN
Over 170 different mutations in the gene encoding SOD1 all cause amyotrophic lateral sclerosis (ALS). Available studies have been primarily focused on the mechanisms underlying mutant SOD1 cytotoxicity. How cells defend against the cytotoxicity remains largely unknown. Here, we show that misfolding of ALS-linked SOD1 mutants and wild-type (wt) SOD1 exposes a normally buried nuclear export signal (NES)-like sequence. The nuclear export carrier protein CRM1 recognizes this NES-like sequence and exports misfolded SOD1 to the cytoplasm. Antibodies against the NES-like sequence recognize misfolded SOD1, but not native wt SOD1 both in vitro and in vivo. Disruption of the NES consensus sequence relocalizes mutant SOD1 to the nucleus, resulting in higher toxicity in cells, and severer impairments in locomotion, egg-laying, and survival in Caenorhabditis elegans. Our data suggest that SOD1 mutants are removed from the nucleus by CRM1 as a defense mechanism against proteotoxicity of misfolded SOD1 in the nucleus.
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Transporte Activo de Núcleo Celular , Carioferinas/metabolismo , Pliegue de Proteína , Receptores Citoplasmáticos y Nucleares/metabolismo , Superóxido Dismutasa-1/metabolismo , Superóxido Dismutasa-1/toxicidad , Secuencias de Aminoácidos , Animales , Caenorhabditis elegans , Proteínas Mutantes/genética , Proteínas Mutantes/metabolismo , Proteínas Mutantes/toxicidad , Unión Proteica , Señales de Clasificación de Proteína , Superóxido Dismutasa-1/química , Proteína Exportina 1RESUMEN
The etiological underpinnings of amyotrophic lateral sclerosis (ALS) are complex and incompletely understood, although contributions to pathogenesis by regulators of proteolytic pathways have become increasingly apparent. Here, we present a novel variant in UBQLN4 that is associated with ALS and show that its expression compromises motor axon morphogenesis in mouse motor neurons and in zebrafish. We further demonstrate that the ALS-associated UBQLN4 variant impairs proteasomal function, and identify the Wnt signaling pathway effector beta-catenin as a UBQLN4 substrate. Inhibition of beta-catenin function rescues the UBQLN4 variant-induced motor axon phenotypes. These findings provide a strong link between the regulation of axonal morphogenesis and a new ALS-associated gene variant mediated by protein degradation pathways.
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Esclerosis Amiotrófica Lateral/genética , Esclerosis Amiotrófica Lateral/patología , Proteínas Portadoras/genética , Morfogénesis , Neuronas Motoras/citología , Proteínas Nucleares/genética , Animales , Modelos Animales de Enfermedad , Ratones , Complejo de la Endopetidasa Proteasomal/metabolismo , Proteolisis , Pez Cebra , beta Catenina/metabolismoRESUMEN
RATIONALE: Amyotrophic lateral sclerosis (ALS) is a progressive neuromuscular disease resulting in respiratory failure and death. Use of noninvasive ventilation (NIV) improves survival. However, use of volume-assured pressure support (VAPS) has not been extensively studied in ALS. OBJECTIVES: To explore the clinical usefulness of a detailed evaluation of device-recorded NIV data in the management of chronic respiratory failure in ALS, and to determine whether there are differences in efficacy between patients using VAPS or PS. METHODS: We performed a retrospective chart review of 271 patients with ALS using either PS or VAPS, along with an evaluation of device-recorded data to explore differences in attainment of goal tidal volumes (Vt) and ratio of respiratory rate to tidal volume (f/Vt), in addition to triggering and cycling ability. RESULTS: Two hundred and fifteen patients were using PS, while 56 were using VAPS. There were no significant differences in demographic data, symptoms, pulmonary function, or patient compliance. Compared with VAPS, achieved Vt was significantly lower for PS while f/Vt was significantly higher. Percent spontaneous triggering was relatively preserved in both cohorts, whereas percent spontaneous cycling was considerably decreased in both. Furthermore, there was no association found between spontaneous triggering or cycling, and pulmonary function, indicating the presence of low spontaneous breath cycling or triggering ability is difficult to predict. CONCLUSIONS: Examination of device data for exhaled tidal volumes and f/Vt may be of use in evaluating efficacy of NIV in ALS. VAPS provides more reliable goal Vt than does PS, and is associated with decreased f/Vt. Spontaneous cycling is decreased in ALS despite preservation of triggering ability. Although a set backup rate may address decreased triggering, perhaps more importantly, setting a sufficient fixed inspiratory time would address the issue of decreased cycling.
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Esclerosis Amiotrófica Lateral/fisiopatología , Respiración , Volumen de Ventilación Pulmonar/fisiología , Esclerosis Amiotrófica Lateral/complicaciones , Esclerosis Amiotrófica Lateral/terapia , Humanos , Ventilación no Invasiva , Insuficiencia Respiratoria/etiología , Insuficiencia Respiratoria/terapia , Estudios RetrospectivosRESUMEN
TMEM230 is a newly identified Parkinson's disease (PD) gene encoding a transmembrane protein whose cellular and pathogenic roles remain largely unknown. Here, we demonstrate that loss of TMEM230 disrupts retromer cargo CI-M6PR (cation-independent mannose 6-phosphate receptor) trafficking and autophagic cargo degradation rates. TMEM230 depletion further inhibits extracellular secretion of the autophagic cargo p62 and immature lysosomal hydrolases in Golgi-derived vesicles leading to their intracellular accumulation, and is specifically mediated by loss of the small GTPase Rab8a. Importantly, PD-linked TMEM230 variants also induce retromer mislocalization, defective cargo trafficking, and impaired autophagy. Finally, we show that knockdown of another PD gene, LRRK2, which phosphorylates Rab8a, similarly impairs retromer trafficking, secretory autophagy and Golgi-derived vesicle secretion, thus demonstrating converging roles of two PD genes TMEM230 and LRRK2 on Rab8a function, and suggesting that retromer and secretory dysfunction play an important role in PD pathogenesis.