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Several widely publicized incidents of academic research misconduct, combined with the politicization of the role of science in public health and policy discourse (e.g., COVID, immunizations) threaten to undermine faith in the integrity of empirical research. Researchers often maintain that peer-review and study replication allow the field to self-police and self-correct; however, stark disparities between official reports of academic research misconduct and self-reports of academic researchers, specifically with regard to data fabrication, belie this argument. Further, systemic imperatives in academic settings often incentivize institutional responses that focus on minimizing reputational harm rather than the impact of fabricated data on the integrity of extant and future research.
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Canine degenerative myelopathy (DM) is a progressive neurological disorder that may be considered to be a large animal model for specific forms of the fatal human disease, familial amyotrophic lateral sclerosis (fALS). DM is associated with a c118G>A mutation of the superoxide dismutase 1 (Sod1) gene, and a significant proportion of cases are inherited in an autosomal recessive manner in contrast to the largely, but not exclusively, dominant mode of inheritance in fALS. The consensus view is that these Sod1/SOD1 mutations result in a toxic gain of function but the mechanisms remain unclear. Here we used an in vitro neuroblastoma cell line transfection system to monitor wild-type and mutant forms of SOD1 fusion proteins containing either a Cherry or an enhanced green fluorescent protein (EGFP) tag. These fusion proteins retained SOD1 enzymatic activity on a native gel assay system. We demonstrate that SOD1 aggregate density is significantly higher in DM transfectants compared to wild-type. In addition, we show by co-immunoprecipitation and confocal microscopy, evidence for a potential interaction between wild-type and mutant forms of SOD1 in co-transfected cells. While in vitro studies have shown SOD1 heterodimer formation in fALS models, this is the first report for DM SOD1. Therefore, despite for the majority of cases there is a difference in the mode of inheritance between fALS and DM, a similar interaction between wild-type and mutant SOD1 forms can occur. Clarifying the role of SOD1 in DM may also be of benefit to understanding the role of SOD1 in fALS.
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Esclerosis Amiotrófica Lateral/genética , Mutación/genética , Superóxido Dismutasa-1/genética , Superóxido Dismutasa/genética , Animales , Línea Celular , Modelos Animales de Enfermedad , Perros , Proteínas Fluorescentes Verdes/genética , Humanos , Enfermedades de la Médula Espinal/genéticaRESUMEN
Recent genetic evidence suggests that aberrant glycosphingolipid metabolism plays an important role in several neuromuscular diseases including hereditary spastic paraplegia, hereditary sensory neuropathy type 1, and non-5q spinal muscular atrophy. Here, we investigated whether altered glycosphingolipid metabolism is a modulator of disease course in amyotrophic lateral sclerosis (ALS). Levels of ceramide, glucosylceramide, galactocerebroside, lactosylceramide, globotriaosylceramide, and the gangliosides GM3 and GM1 were significantly elevated in spinal cords of ALS patients. Moreover, enzyme activities (glucocerebrosidase-1, glucocerebrosidase-2, hexosaminidase, galactosylceramidase, α-galactosidase, and ß-galactosidase) mediating glycosphingolipid hydrolysis were also elevated up to threefold. Increased ceramide, glucosylceramide, GM3, and hexosaminidase activity were also found in SOD1(G93A) mice, a familial model of ALS. Inhibition of glucosylceramide synthesis accelerated disease course in SOD1(G93A) mice, whereas infusion of exogenous GM3 significantly slowed the onset of paralysis and increased survival. Our results suggest that glycosphingolipids are likely important participants in pathogenesis of ALS and merit further analysis as potential drug targets.
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Esclerosis Amiotrófica Lateral/fisiopatología , Glicoesfingolípidos/fisiología , Esclerosis Amiotrófica Lateral/enzimología , Animales , Modelos Animales de Enfermedad , Progresión de la Enfermedad , Gangliósido G(M3)/administración & dosificación , Glucosiltransferasas/antagonistas & inhibidores , Humanos , Inyecciones Intraventriculares , Masculino , Ratones , Ratones Transgénicos , Médula Espinal/fisiopatología , Superóxido Dismutasa/genética , Superóxido Dismutasa/metabolismoRESUMEN
Amyotrophic lateral sclerosis (ALS) is a fatal motor neuron disease characterized by upper and lower motor neuron damage in the bulbar and spinal territories. Although the pathophysiology of ALS is still unknown, the involvement of genetic factors is no longer a subject of debate. Familial ALS (fALS) accounts for 10-20% of cases. Since the identification of the SOD1 gene, more than 20 genes have been described, of which four can explain >50% of familial cases. This review is an update focused on major aspects of the field of ALS genetics concerning both causative and susceptibility factors.
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Esclerosis Amiotrófica Lateral/genética , Proteína C9orf72/genética , Humanos , Superóxido Dismutasa-1/genéticaRESUMEN
Although the ubiquitin-proteasome system is believed to play an important role in the pathogenesis of familial amyotrophic lateral sclerosis (FALS), caused by mutations in Cu/Zn-superoxide dismutase 1 (SOD1), the mechanism of how mutant SOD1 protein is regulated in cells is still poorly understood. Here we have demonstrated that cellular inhibitor of apoptosis proteins (cIAPs) are specifically associated with FALS-linked mutant SOD1 (mSOD1) and that this interaction promotes the ubiquitin-dependent proteasomal degradation of mutant SOD1. By utilizing cumate inducible SOD1 cells, we also showed that knock-down or pharmacologic depletion of cIAPs leads to H2O2 induced cytotoxicity in mSOD1 expressing cells. Altogether, our results reveal a novel role of cIAPs in FALS-associated mutant SOD1 regulation.
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Esclerosis Amiotrófica Lateral/metabolismo , Proteínas Inhibidoras de la Apoptosis/metabolismo , Complejo de la Endopetidasa Proteasomal/metabolismo , Superóxido Dismutasa-1/genética , Superóxido Dismutasa-1/metabolismo , Esclerosis Amiotrófica Lateral/genética , Células HEK293 , Humanos , Mutación/genética , UbiquitinaciónRESUMEN
Evidence of misfolded wild-type superoxide dismutase 1 (SOD1) has been detected in spinal cords of sporadic ALS (sALS) patients, suggesting an etiological relationship to SOD1-associated familial ALS (fALS). Given that there are currently a number of promising therapies under development that target SOD1, it is of critical importance to better understand the role of misfolded SOD1 in sALS. We previously demonstrated the permissiveness of the G85R-SOD1:YFP mouse model for MND induction following injection with tissue homogenates from paralyzed transgenic mice expressing SOD1 mutations. This prompted us to examine whether WT SOD1 can self-propagate misfolding of the G85R-SOD1:YFP protein akin to what has been observed with mutant SOD1. Using the G85R-SOD1:YFP mice, we demonstrate that misfolded conformers of recombinant WT SOD1, produced in vitro, induce MND with a distinct inclusion pathology. Furthermore, the distinct pathology remains upon successive passages in the G85R-SOD1:YFP mice, strongly supporting the notion for conformation-dependent templated propagation and SOD1 strains. To determine the presence of a similar misfolded WT SOD1 conformer in sALS tissue, we screened homogenates from patients diagnosed with sALS, fALS, and non-ALS disease in an organotypic spinal cord slice culture assay. Slice cultures from G85R-SOD1:YFP mice exposed to spinal homogenates from patients diagnosed with ALS caused by the A4V mutation in SOD1 developed robust inclusion pathology, whereas spinal homogenates from more than 30 sALS cases and various controls failed. These findings suggest that mutant SOD1 has prion-like attributes that do not extend to SOD1 in sALS tissues.
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Esclerosis Amiotrófica Lateral/genética , Superóxido Dismutasa-1/genética , Amiloide/genética , Amiloide/metabolismo , Esclerosis Amiotrófica Lateral/diagnóstico , Esclerosis Amiotrófica Lateral/patología , Análisis de Varianza , Animales , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Modelos Animales de Enfermedad , Humanos , Técnicas In Vitro , Proteínas Luminiscentes/genética , Proteínas Luminiscentes/metabolismo , Ratones , Ratones Transgénicos , Microscopía Electrónica , Mutación/genética , Técnicas de Cultivo de Órganos , Pliegue de Proteína , Deficiencias en la Proteostasis/diagnóstico , Deficiencias en la Proteostasis/genética , Médula Espinal/metabolismo , Médula Espinal/patología , Médula Espinal/ultraestructura , Superóxido Dismutasa-1/metabolismoRESUMEN
Protein misfolding is considered to be a potential contributing factor for motor neuron and muscle loss in diseases like Amyotrophic lateral sclerosis (ALS). Several independent studies have demonstrated using over-expressed mutated Cu/Zn-superoxide dismutase (mSOD1) transgenic mouse models which mimic familial ALS (f-ALS), that both muscle and motor neurons undergo degeneration during disease progression. However, it is unknown whether protein conformation of skeletal muscle and spinal cord is equally or differentially affected by mSOD1-induced toxicity. It is also unclear whether heat shock proteins (Hsp's) differentially modulate skeletal muscle and spinal cord protein structure during ALS disease progression. We report three intriguing observations utilizing the f-ALS mouse model and cell-free in vitro system; (i) muscle proteins are equally sensitive to misfolding as spinal cord proteins despite the presence of low level of soluble and absence of insoluble G93A protein aggregate, unlike in spinal cord, (ii) Hsp's levels are lower in muscle compared to spinal cord at any stage of the disease, and (iii) G93ASOD1 enzyme-induced toxicity selectively affects muscle protein conformation over spinal cord proteins. Together, these findings strongly suggest that differential chaperone levels between skeletal muscle and spinal cord may be a critical determinant for G93A-induced protein misfolding in ALS.
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Esclerosis Amiotrófica Lateral/metabolismo , Modelos Animales de Enfermedad , Proteínas de Choque Térmico/metabolismo , Chaperonas Moleculares/metabolismo , Músculo Esquelético/metabolismo , Médula Espinal/metabolismo , Superóxido Dismutasa/metabolismo , Esclerosis Amiotrófica Lateral/genética , Animales , Proteínas de Choque Térmico/genética , Humanos , Masculino , Ratones , Ratones Transgénicos , Chaperonas Moleculares/genética , Mutación/genética , Transducción de Señal/genética , Especificidad de la Especie , Relación Estructura-Actividad , Superóxido Dismutasa/genética , Distribución TisularRESUMEN
We report the first Italian kindred with Familial Amyotrophic Lateral Sclerosis (FALS) due to c.149T>C mutation in the exon 5 of superoxide dismutase-1 (SOD1) gene. The proband was a 49-year-old woman who came to our observation because of an history of progressive limbs weakness and gait impairment. She belonged to a family of 24 affected members. The prevalent phenotype of the affected members was characterized by slowly progressive spinal impairment with proximal distribution of weakness, and bulbar involvement in advanced stages. We briefly reviewed the few previous reports about the same SOD1 mutation and discussed the hypothesis that structural instability of the mutant codon 149 protein may underlie some toxic effects significantly involved in FALS pathogenesis.
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Esclerosis Amiotrófica Lateral/genética , ADN/genética , Familia , Predisposición Genética a la Enfermedad , Mutación , Superóxido Dismutasa/genética , Esclerosis Amiotrófica Lateral/metabolismo , Análisis Mutacional de ADN , Exones , Femenino , Genotipo , Humanos , Persona de Mediana Edad , Linaje , Superóxido Dismutasa/metabolismo , Superóxido Dismutasa-1RESUMEN
Amyotrophic lateral sclerosis (ALS) is a fatal, progressive neurodegenerative disease of motor neurons. Most ALS cases are considered sporadic due to the presence of a combination of environmental and complex genetic risk factors, while approximately 10% of cases have a family history. Pathogenic variants in the SOD1 gene are the second most frequent causative factor of genetics-based ALS worldwide, after C9ORF72 hexanucleotide repeat expansion. The De novo occurrence of pathogenic mutations in ALS-associated genes and its effect on disease progression have been studied previously, especially in the FUS gene. Recent studies have shown that a very small portion of SOD1 cases occurred de novo. Here, we present the first de novo case of the SOD1 His47Arg mutation in a young female patient with mild symptoms and, currently, a slow progression for 7 years.
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Background: Individuals with limited health literacy often struggle in effectively communicating with their physicians and may lack the skills needed to make informed health decisions. It is therefore important that providers have insight into patients' baseline medical knowledge, as this can help physicians customize their approach to, and conversations with, each patient. As such, this study evaluated the foot and ankle-specific knowledge of patients seeking care for various foot and ankle ailments. Methods: An unvalidated survey developed by our study group was distributed to 206 patients, assessing their knowledge of foot and ankle anatomy, terminology, conditions, treatment, and perioperative issues. Performance was evaluated as a function of participants' demographic factors. Results: Participants performed significantly worse on the conditions and treatment questions as compared to the anatomy, terminology, and perioperative considerations subsections. Significantly better performance correlated with education (≥college), visit type (preoperative evaluation), a current or previous health care occupation, and prior orthopedic surgeon evaluation. Conclusions: Patients' knowledge of foot and ankle anatomy, terminology, conditions, treatment, and perioperative issues correlates with certain patient characteristics and demographics. With enhanced insight into the risk factors for limited knowledge, education campaigns can be designed to target those most in need.
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We observed a Polish family with familial amyotrophic lateral sclerosis with heterozygous L144S SOD1 mutation, which manifested clinically as flail leg syndrome. Flail leg syndrome is a rare phenotype of amyotrophic lateral sclerosis, with slow progression, long survival, and predominance of lower motor neuron signs at onset, as a triad of distal paresis, muscle atrophy, and hyporeflexia/areflexia, confined to the lower limbs for an extended period of time. Although familial amyotrophic lateral sclerosis is usually associated with a worse prognosis than the sporadic form of the disease, the clinical course of the disease in patients with L144S SOD1 mutation is benign, with slow progression and long survival. This unique case report provides an in-depth clinical analysis of all of the symptomatic members of a family, who were diagnosed with amyotrophic lateral sclerosis in our clinic, including three siblings (two brothers and a deceased sister) with flail leg syndrome and their fraternal aunt, who has been previously misdiagnosed with cervical myelopathy and is living with symptoms of the disease for 15 years. Sanger sequencing of the SOD1 gene was performed in all of the living patients, revealing an L144S (c.434T>C, p.Leu145Ser) heterozygous mutation. The aim of this case report is to increase the physician's awareness of the atypical phenotypes of amyotrophic lateral sclerosis and hopefully, to encourage further research on the factors responsible for delayed disease progression in patients with L144S SOD1 mutation.
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Despite extensive research, amyotrophic lateral sclerosis (ALS) remains a progressive and invariably fatal neurodegenerative disease. Limited knowledge of the underlying causes of ALS has made it difficult to target upstream biological mechanisms of disease, and therapeutic interventions are usually administered relatively late in the course of disease. Genetic forms of ALS offer a unique opportunity for therapeutic development, as genetic associations may reveal potential insights into disease etiology. Genetic ALS may also be amenable to investigating earlier intervention given the possibility of identifying clinically presymptomatic, at-risk individuals with causative genetic variants. There is increasing evidence for a presymptomatic phase of ALS, with biomarker data from the Pre-Symptomatic Familial ALS (Pre-fALS) study showing that an elevation in blood neurofilament light chain (NfL) precedes phenoconversion to clinically manifest disease. Tofersen is an investigational antisense oligonucleotide designed to reduce synthesis of superoxide dismutase 1 (SOD1) protein through degradation of SOD1 mRNA. Informed by Pre-fALS and the tofersen clinical development program, the ATLAS study (NCT04856982) is designed to evaluate the impact of initiating tofersen in presymptomatic carriers of SOD1 variants associated with high or complete penetrance and rapid disease progression who also have biomarker evidence of disease activity (elevated plasma NfL). The ATLAS study will investigate whether tofersen can delay the emergence of clinically manifest ALS. To our knowledge, ATLAS is the first interventional trial in presymptomatic ALS and has the potential to yield important insights into the design and conduct of presymptomatic trials, identification, and monitoring of at-risk individuals, and future treatment paradigms in ALS.
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Esclerosis Amiotrófica Lateral , Enfermedades Neurodegenerativas , Humanos , Superóxido Dismutasa-1/genética , Esclerosis Amiotrófica Lateral/tratamiento farmacológico , Esclerosis Amiotrófica Lateral/genética , Superóxido Dismutasa/genética , Oligonucleótidos Antisentido/uso terapéutico , Biomarcadores , ARN Mensajero , MutaciónRESUMEN
CuATSM has repeatedly demonstrated to be therapeutically effective in SOD1 mouse models of amyotrophic lateral sclerosis (ALS), leading to current clinical trials. CuATSM acts to stabilize ALS-associated mutant SOD1 protein by supplying copper. However, in vitro work has demonstrated that CuATSM is only therapeutic for wild-type-like SOD1 mutants, not metal-binding-region mutants, suggesting that CuATSM may have genotype-specific effects. Furthermore, relatively high doses of CuATSM have been shown to produce adverse events in humans and mice. Here, we investigated the genotype-specific therapeutic window of CuATSM. NSC-34 cells transiently expressing copper-binding or non-binding mutations of SOD1 were treated with a broad range of CuATSM concentrations and examined for survival via time-lapse microscopy. Determination of the no-observed-adverse-effect level and the LC50 suggest that CuATSM-associated toxicity is dependent on the amount of copper-depleted SOD1 available as well as the mutant's ability to bind copper. Our results suggest that the particular variant of SOD1 mutant is crucial in not only determining the level of efficacy achieved but also potential adverse events.
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Esclerosis Amiotrófica Lateral , Esclerosis Amiotrófica Lateral/metabolismo , Animales , Quelantes/uso terapéutico , Cobre/metabolismo , Modelos Animales de Enfermedad , Susceptibilidad a Enfermedades , Humanos , Ratones , Ratones Transgénicos , Mutación/genética , Superóxido Dismutasa/genética , Superóxido Dismutasa/metabolismo , Superóxido Dismutasa-1/genéticaRESUMEN
Aggregation of profilin-1 (PFN1) causes a fatal neurodegenerative disease, familial amyotrophic lateral sclerosis (fALS). Histidine (His) tautomerism has been linked to the formation of fibril aggregation causing neurodegenerative disease. Characterization of intermediate species that form during aggregation is crucial, however, this has proven very challenging for experimentalists due to their transient nature. Hence, molecular dynamics (MD) simulations have been performed on the His tautomeric isomers εε, εδ, δε, and δδ of PFN1 to explain the structural changes and to correlate them with its aggregation propensity. MD simulations show that His133 presumably plays a major role in the aggregation of PFN1 upon His tautomerism compared to His119. Further, the formation of a new 310-helix is observed in εε and δε but 310-helix is not observed in δδ and εδ isomers. In addition, our findings unveil that ß-sheet dominating conformations are observed in His119(δ)-His133(δ) δδ isomer of PFN1 with significant antiparallel ß-sheets between residues T15-G23, S29-A33, L63-L65, Q68-S76, F83-T89, T97-T105, and K107-K115, suggesting a novel aggregation mechanism possibly occur for the formation of PFN1 aggregates. Overall, these results propose that MD simulations of PFN1 His tautomers can provide a detailed microscopic understanding of the aggregation mechanisms which are hard to probe through experiments.
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Esclerosis Amiotrófica Lateral , Histidina , Enfermedades Neurodegenerativas , Profilinas , Esclerosis Amiotrófica Lateral/metabolismo , Histidina/metabolismo , Humanos , Mutación , Profilinas/química , Profilinas/genética , Profilinas/metabolismo , Agregado de Proteínas , Conformación ProteicaRESUMEN
OBJECTIVE: This study aimed to determine the distribution of the most commonly mutated genes (SOD1, TARDBP, FUS/TLS, and C9ORF72) associated with familial amyotrophic lateral sclerosis (FALS) and the association between genotype and phenotype in 242 Chinese patients. METHODS: A total of 58 families were screened for ALS-associated mutations in SOD1ï¼TARDBP, FUS, and C9ORF72 hexanucleotide repeat expansion. These mutations were analyzed to evaluate the relationship between genotype and phenotype in Chinese FALS patients. RESULTS: Partial clinical data were obtained for 242 relatives of the 58 analyzed families, with a male-to-female ratio of 1.2:1 and a mean age of disease onset of 45.9±12.0 (13-80) years. 26 mutations associated with pathogenesis were identified in 32 probands from 58 different families. Mutations in SOD1, FUS, TARDBP, and C9ORF72 accounted for 32.8%, 12.1%, 8.6%, and 1.7% of FALS, respectively. FALS patients showed longer survival times; however, bulbar-onset ALS and the male-to-female ratio for them were lower than those reported previously. The site of onset, age of onset, and lifespan differed in FALS patients with SOD1, TARDBP, and FUS mutations. DISCUSSION: In this study, patients with SOD1 mutations exhibited heterogeneous survival times that showed a bimodal distribution, while patients with FUS mutations showed rapid disease progression. Our results showed the relative contributions of the different types of mutations associated with ALS and provided phenotype-genotype correlations with clinical features in Chinese patients.
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Esclerosis Amiotrófica Lateral/genética , Esclerosis Amiotrófica Lateral/mortalidad , Esclerosis Amiotrófica Lateral/fisiopatología , Progresión de la Enfermedad , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , China/epidemiología , Femenino , Estudios de Asociación Genética , Humanos , Masculino , Persona de Mediana Edad , Linaje , Adulto JovenRESUMEN
Microbial metabolites affect the neuron system and muscle cell functions. Amyotrophic lateral sclerosis (ALS) is a multifactorial neuromuscular disease. Our previous study has demonstrated elevated intestinal inflammation and dysfunction of the microbiome in patients with ALS and an ALS mouse model (human-SOD1G93A transgenic mice). However, the metabolites in ALS progression are unknown. Using an unbiased global metabolomic measurement and targeted measurement, we investigated the longitudinal changes of fecal metabolites in SOD1G93A mice over the course of 13 weeks. We further compared the changes of metabolites and inflammatory response in age-matched wild-type (WT) and SOD1G93A mice treated with the bacterial product butyrate. We found changes in carbohydrate levels, amino acid metabolism, and the formation of gamma-glutamyl amino acids. Shifts in several microbially contributed catabolites of aromatic amino acids agree with butyrate-induced changes in the composition of the gut microbiome. Declines in gamma-glutamyl amino acids in feces may stem from differential expression of gamma-glutamyltransferase (GGT) in response to butyrate administration. Due to the signaling nature of amino acid-derived metabolites, these changes indicate changes in inflammation, e.g., histamine, and contribute to differences in systemic levels of neurotransmitters, e.g., γ-Aminobutyric acid (GABA) and glutamate. Butyrate treatment was able to restore some of the healthy metabolites in ALS mice. Moreover, microglia in the spinal cord were measured by IBA1 staining. Butyrate treatment significantly suppressed the IBA1 level in the SOD1G93A mice. Serum IL-17 and LPS were significantly reduced in the butyrate-treated SOD1G93A mice. We have demonstrated an inter-organ communications link among microbial metabolites, neuroactive metabolites from the gut, and inflammation in ALS progression. The study supports the potential to use metabolites as ALS hallmarks and for treatment.
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Here, we aim to provide a comprehensive clinical and biomolecular description of familial amyotrophic lateral sclerosis (fALS) in a 25-year-old female patient with respect to the SOD1A4T genotype. The clinical diagnosis of the disease was based on family history, neurological examination, electroneurophysiological studies, and revised El Escorial criteria. The heterozygous presence of the A4T mutation in the proband was confirmed by PCR coupled with Sanger sequencing of exon 1 of the SOD1 gene. The mutation was introduced in silico into the three-dimensional structure of the native protein. After energy minimization and quality assessment, non-covalent interactions around threonine-4 and changes in protein stability were calculated computationally. The patient differed widely in age at onset, initial neurological symptoms and findings, and survival time from her kindred, in which several members are affected. SOD1A4T-linked fALS in this case had bulbar involvement at onset, a combination of lower and upper motor neuron signs and showed rapid progression. Unlike alanine-4, threonine-4 failed to engage in hydrophobic interactions with the vicinal non-polar amino acids. The overall fold of the modeled SOD1A4T mutant remained intact, but unfolding free energy estimations disclosed a decrease in the protein's stability. We report a phenotypically distinct patient with fALS due to the SOD1A4T mutation and further expand the largest pedigree ever published for SOD1A4T-linked fALS. Genotypeâphenotype correlation in fALS is complex, and it demands detailed clinical investigation and advanced scientific research. Awareness of the broadened phenotypic spectrum might potentially enhance the diagnosis and genetic counseling of fALS.
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Esclerosis Amiotrófica Lateral , Esclerosis Amiotrófica Lateral/genética , Femenino , Humanos , Mutación , Superóxido Dismutasa/genética , Superóxido Dismutasa/metabolismo , Superóxido Dismutasa-1/genética , Treonina/genéticaRESUMEN
Living organisms are subject to various mechanical stressors, such as high hydrostatic pressure. Empirical evidence shows that under high pressure, the oxidative stress response is activated in Saccharomyces cerevisiae. However, the mechanisms involved in its antioxidant systems are unclear. Here, we demonstrate that superoxide dismutase 1 (Sod1) plays a role in resisting high pressure for cell growth. Mutants lacking Sod1 or Ccs1, the copper chaperone for Sod1, displayed growth defects under 25 MPa. Of the various SOD1 mutations associated with familial amyotrophic lateral sclerosis, H46Q and S134N substitutions diminished SOD activity to levels comparable to those of catalytically deficient H63A and null mutants. When these mutant cells were cultured under 25 MPa, their intracellular O2â¢- levels increased while sod1∆ mutant genome stability was unaffected. The high-pressure sensitive sod1 mutants were also susceptible to sublethal levels of the O2â¢- generator paraquat. The sod1∆ mutant is known to exhibit methionine and lysine auxotrophy. However, excess methionine addition or overexpression of the lysine permease gene LYP1 did not counteract high-pressure sensitivity in the sod1 mutants, suggesting that their amino acid availability might be intact under 25 MPa. Interestingly, an exclusive localization of Sco2-Sod1 to the intermembrane space (IMS) of mitochondria appeared to partially restore the high-pressure growth ability in the sod1 mutants. Taken these results together, we suggest that high pressure enhances O2â¢- production and Sod1 within the IMS plays a role in scavenging O2â¢- allowing the cells to grow under high pressure. BACKGROUND: Empirical evidence shows that under high hydrostatic pressure, the oxidative stress response is activated in Saccharomyces cerevisiae. However, the mechanisms involved in its antioxidant systems are unclear. In the current study, we aimed to explore the role of superoxide dismutase 1 (Sod1) in yeast able to grow under high pressure. METHODS: Wild type and sod1 mutant cells were cultured in high-pressure chambers under 25 MPa (~250 kg/cm2). The SOD activity in whole cell extracts and 6His-tagged Sod1 recombinant proteins was analyzed using an SOD assay kit. The O2â¢- generation in cells was estimated by fluorescence staining. RESULTS: Mutants lacking Sod1 or Ccs1, the copper chaperone for Sod1, displayed growth defects under 25 MPa. Of the various SOD1 mutations associated with familial amyotrophic lateral sclerosis, H46Q and S134N substitutions diminished SOD activity to levels comparable to those of catalytically deficient H63A and null mutants. The high-pressure sensitive sod1 mutants were also susceptible to sublethal levels of the O2â¢- generator paraquat. Exclusive localization of Sco2-Sod1 to the intermembrane space (IMS) of mitochondria partially restored the high-pressure growth ability in the sod1 mutants. CONCLUSIONS: High pressure enhances O2â¢- production and Sod1 within the IMS plays a role in scavenging O2â¢- allowing the cells to grow under high pressure. GENERAL SIGNIFICANCE: Unlike external free radical-generating compounds, high-pressure treatment appeared to increase endogenous O2â¢- levels in yeast cells. Our experimental system offers a unique approach to investigating the physiological responses to mechanical and oxidative stresses in human body.
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Saccharomyces cerevisiaeRESUMEN
Amyotrophic Lateral Sclerosis is a neuromuscular disease characterized by the progressive death of motor neurons and muscle atrophy. The gastrointestinal symptoms in ALS patients were largely ignored or underestimated. The relationship between the enteric neuromuscular system and microbiome in ALS progression is unknown. We performed longitudinal studies on the enteric neuron system (ENS) and microbiome in the ALS human-SOD1G93A (Superoxide Dismutase 1) transgenic mice. We treated age-matched wild-type and ALS mice with butyrate or antibiotics to investigate the microbiome and neuromuscular functions. We examined intestinal mobility, microbiome, an ENS marker GFAP (Glial Fibrillary Acidic Protein), a smooth muscle marker (SMMHC, Smooth Muscle Myosin Heavy Chain), and human colonoids. The distribution of human-G93A-SOD1 protein was tested as an indicator of ALS progression. At 2-month-old before ALS onset, SOD1G93A mice had significantly lower intestinal mobility, decreased grip strength, and reduced time in the rotarod. We observed increased GFAP and decreased SMMHC expression. These changes correlated with consistent increased aggregation of mutated SOD1G93A in the colon, small intestine, and spinal cord. Butyrate or antibiotics treated SOD1G93A mice had a significantly longer latency to fall in the rotarod test, reduced SOD1G93A aggregation, and enhanced enteric neuromuscular function. Feces from 2-month-old SOD1G93A mice significantly enhanced SOD1G93A aggregation in human colonoids transfected with a SOD1G93A-GFP plasmid. Longitudinal studies of microbiome data further showed the altered bacterial community related to autoimmunity (e.g., Clostridium sp. ASF502, Lachnospiraceae bacterium A4), inflammation (e.g., Enterohabdus Muris,), and metabolism (e.g., Desulfovibrio fairfieldensis) at 1- and 2-month-old SOD1G93A mice, suggesting the early microbial contribution to the pathological changes. We have demonstrated a novel link between the microbiome, hSOD1G93A aggregation, and intestinal mobility. Dysbiosis occurred at the early stage of the ALS mice before observed mutated-SOD1 aggregation and dysfunction of ENS. Manipulating the microbiome improves the muscle performance of SOD1G93A mice. We provide insights into the fundamentals of intestinal neuromuscular function and microbiome in ALS.