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1.
Cell ; 180(6): 1228-1244.e24, 2020 03 19.
Artículo en Inglés | MEDLINE | ID: mdl-32142649

RESUMEN

Transcription-coupled nucleotide excision repair (TC-NER) is initiated by the stalling of elongating RNA polymerase II (RNAPIIo) at DNA lesions. The ubiquitination of RNAPIIo in response to DNA damage is an evolutionarily conserved event, but its function in mammals is unknown. Here, we identified a single DNA damage-induced ubiquitination site in RNAPII at RPB1-K1268, which regulates transcription recovery and DNA damage resistance. Mechanistically, RPB1-K1268 ubiquitination stimulates the association of the core-TFIIH complex with stalled RNAPIIo through a transfer mechanism that also involves UVSSA-K414 ubiquitination. We developed a strand-specific ChIP-seq method, which revealed RPB1-K1268 ubiquitination is important for repair and the resolution of transcriptional bottlenecks at DNA lesions. Finally, RPB1-K1268R knockin mice displayed a short life-span, premature aging, and neurodegeneration. Our results reveal RNAPII ubiquitination provides a two-tier protection mechanism by activating TC-NER and, in parallel, the processing of DNA damage-stalled RNAPIIo, which together prevent prolonged transcription arrest and protect against neurodegeneration.


Asunto(s)
Reparación del ADN/fisiología , ARN Polimerasa II/metabolismo , Animales , Proteínas Portadoras/genética , Proteínas Portadoras/metabolismo , ADN/metabolismo , Daño del ADN/fisiología , ADN Helicasas/metabolismo , Enzimas Reparadoras del ADN/genética , Enzimas Reparadoras del ADN/metabolismo , Femenino , Células HCT116 , Células HEK293 , Células HeLa , Humanos , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , ARN Polimerasa II/genética , Ubiquitinación
2.
Proc Natl Acad Sci U S A ; 120(47): e2315347120, 2023 Nov 21.
Artículo en Inglés | MEDLINE | ID: mdl-37967220

RESUMEN

The organelle contact site of the endoplasmic reticulum and mitochondria, known as the mitochondria-associated membrane (MAM), is a multifunctional microdomain in cellular homeostasis. We previously reported that MAM disruption is a common pathological feature in amyotrophic lateral sclerosis (ALS); however, the precise role of MAM in ALS was uncovered. Here, we show that the MAM is essential for TANK-binding kinase 1 (TBK1) activation under proteostatic stress conditions. A MAM-specific E3 ubiquitin ligase, autocrine motility factor receptor, ubiquitinated nascent proteins to activate TBK1 at the MAM, which results in ribosomal protein degradation. MAM or TBK1 deficiency under proteostatic stress conditions resulted in increased cellular vulnerability in vitro and motor impairment in vivo. Thus, MAM disruption exacerbates proteostatic stress via TBK1 inactivation in ALS. Our study has revealed a proteostatic mechanism mediated by the MAM-TBK1 axis, highlighting the physiological importance of the organelle contact sites.


Asunto(s)
Esclerosis Amiotrófica Lateral , Humanos , Esclerosis Amiotrófica Lateral/metabolismo , Mitocondrias/metabolismo , Membranas Mitocondriales/metabolismo , Retículo Endoplásmico/metabolismo , Proteínas Serina-Treonina Quinasas/genética , Proteínas Serina-Treonina Quinasas/metabolismo
3.
J Biol Chem ; 299(6): 104798, 2023 06.
Artículo en Inglés | MEDLINE | ID: mdl-37156398

RESUMEN

Canine degenerative myelopathy (DM), a fatal neurodegenerative disease in dogs, shares clinical and genetic features with amyotrophic lateral sclerosis, a human motor neuron disease. Mutations in the SOD1 gene encoding Cu/Zn superoxide dismutase (SOD1) cause canine DM and a subset of inherited human amyotrophic lateral sclerosis. The most frequent DM causative mutation is homozygous E40K mutation, which induces the aggregation of canine SOD1 but not of human SOD1. However, the mechanism through which canine E40K mutation induces species-specific aggregation of SOD1 remains unknown. By screening human/canine chimeric SOD1s, we identified that the humanized mutation of the 117th residue (M117L), encoded by exon 4, significantly reduced aggregation propensity of canine SOD1E40K. Conversely, introducing a mutation of leucine 117 to methionine, a residue homologous to canine, promoted E40K-dependent aggregation in human SOD1. M117L mutation improved protein stability and reduced cytotoxicity of canine SOD1E40K. Furthermore, crystal structural analysis of canine SOD1 proteins revealed that M117L increased the packing within the hydrophobic core of the ß-barrel structure, contributing to the increased protein stability. Our findings indicate that the structural vulnerability derived intrinsically from Met 117 in the hydrophobic core of the ß-barrel structure induces E40K-dependent species-specific aggregation in canine SOD1.


Asunto(s)
Enfermedades de los Perros , Mutación , Enfermedades Neurodegenerativas , Superóxido Dismutasa-1 , Animales , Perros , Humanos , Esclerosis Amiotrófica Lateral/genética , Esclerosis Amiotrófica Lateral/metabolismo , Enfermedades Neurodegenerativas/genética , Enfermedades Neurodegenerativas/metabolismo , Enfermedades Neurodegenerativas/veterinaria , Superóxido Dismutasa-1/genética , Superóxido Dismutasa-1/metabolismo , Enfermedades de los Perros/genética , Enfermedades de los Perros/metabolismo , Especificidad de la Especie
4.
EMBO J ; 39(22): e104464, 2020 11 16.
Artículo en Inglés | MEDLINE | ID: mdl-32959911

RESUMEN

Microglia are the principal phagocytes that clear cell debris in the central nervous system (CNS). This raises the question, which cells remove cell debris when microglial phagocytic activity is impaired. We addressed this question using Siglechdtr mice, which enable highly specific ablation of microglia. Non-microglial mononuclear phagocytes, such as CNS-associated macrophages and circulating inflammatory monocytes, did not clear microglial debris. Instead, astrocytes were activated, exhibited a pro-inflammatory gene expression profile, and extended their processes to engulf microglial debris. This astrocytic phagocytosis was also observed in Irf8-deficient mice, in which microglia were present but dysfunctional. RNA-seq demonstrated that even in a healthy CNS, astrocytes express TAM phagocytic receptors, which were the main astrocytic phagocytic receptors for cell debris in the above experiments, indicating that astrocytes stand by in case of microglial impairment. This compensatory mechanism may be important for the maintenance or prolongation of a healthy CNS.


Asunto(s)
Astrocitos/fisiología , Microglía/metabolismo , Fagocitosis/fisiología , Animales , Astrocitos/citología , Encéfalo , Sistema Nervioso Central/fisiología , Modelos Animales de Enfermedad , Femenino , Factores Reguladores del Interferón/deficiencia , Factores Reguladores del Interferón/genética , Masculino , Ratones , Ratones Noqueados , Microglía/ultraestructura , Fagocitosis/genética
5.
J Neuroinflammation ; 21(1): 55, 2024 Feb 21.
Artículo en Inglés | MEDLINE | ID: mdl-38383481

RESUMEN

BACKGROUND: Neuroinflammation substantially contributes to the pathology of Alzheimer's disease (AD), the most common form of dementia. Studies have reported that nuclear factor erythroid 2-related factor 2 (Nrf2) attenuates neuroinflammation in the mouse models of neurodegenerative diseases, however, the detailed mechanism remains unclear. METHODS: The effects of dimethyl fumarate (DMF), a clinically used drug to activate the Nrf2 pathway, on neuroinflammation were analyzed in primary astrocytes and AppNL-G-F (App-KI) mice. The cognitive function and behavior of DMF-administrated App-KI mice were evaluated. For the gene expression analysis, microglia and astrocytes were directly isolated from the mouse cerebral cortex by magnetic-activated cell sorting, followed by quantitative PCR. RESULTS: DMF treatment activated some Nrf2 target genes and inhibited the expression of proinflammatory markers in primary astrocytes. Moreover, chronic oral administration of DMF attenuated neuroinflammation, particularly in astrocytes, and reversed cognitive dysfunction presumably by activating the Nrf2-dependent pathway in App-KI mice. Furthermore, DMF administration inhibited the expression of STAT3/C3 and C3 receptor in astrocytes and microglia isolated from App-KI mice, respectively, suggesting that the astrocyte-microglia crosstalk is involved in neuroinflammation in mice with AD. CONCLUSION: The activation of astrocytic Nrf2 signaling confers neuroprotection in mice with AD by controlling neuroinflammation, particularly by regulating astrocytic C3-STAT3 signaling. Furthermore, our study has implications for the repositioning of DMF as a drug for AD treatment.


Asunto(s)
Enfermedad de Alzheimer , Disfunción Cognitiva , Ratones , Animales , Enfermedad de Alzheimer/complicaciones , Enfermedad de Alzheimer/tratamiento farmacológico , Enfermedad de Alzheimer/genética , Dimetilfumarato/farmacología , Dimetilfumarato/uso terapéutico , Ratones Transgénicos , Enfermedades Neuroinflamatorias , Factor 2 Relacionado con NF-E2/metabolismo , Disfunción Cognitiva/tratamiento farmacológico , Disfunción Cognitiva/etiología , Modelos Animales de Enfermedad
6.
Acta Neuropathol ; 147(1): 84, 2024 05 15.
Artículo en Inglés | MEDLINE | ID: mdl-38750212

RESUMEN

Amyotrophic Lateral Sclerosis/Parkinsonism-Dementia Complex (ALS/PDC), a rare and complex neurological disorder, is predominantly observed in the Western Pacific islands, including regions of Japan, Guam, and Papua. This enigmatic condition continues to capture medical attention due to affected patients displaying symptoms that parallel those seen in either classical amyotrophic lateral sclerosis (ALS) or Parkinson's disease (PD). Distinctly, postmortem examinations of the brains of affected individuals have shown the presence of α-synuclein aggregates and TDP-43, which are hallmarks of PD and classical ALS, respectively. These observations are further complicated by the detection of phosphorylated tau, accentuating the multifaceted proteinopathic nature of ALS/PDC. The etiological foundations of this disease remain undetermined, and genetic investigations have yet to provide conclusive answers. However, emerging evidence has implicated the contribution of astrocytes, pivotal cells for maintaining brain health, to neurodegenerative onset, and likely to play a significant role in the pathogenesis of ALS/PDC. Leveraging advanced induced pluripotent stem cell technology, our team cultivated multiple astrocyte lines to further investigate the Japanese variant of ALS/PDC (Kii ALS/PDC). CHCHD2 emerged as a significantly dysregulated gene when disease astrocytes were compared to healthy controls. Our analyses also revealed imbalances in the activation of specific pathways: those associated with astrocytic cilium dysfunction, known to be involved in neurodegeneration, and those related to major neurological disorders, including classical ALS and PD. Further in-depth examinations revealed abnormalities in the mitochondrial morphology and metabolic processes of the affected astrocytes. A particularly striking observation was the reduced expression of CHCHD2 in the spinal cord, motor cortex, and oculomotor nuclei of patients with Kii ALS/PDC. In summary, our findings suggest a potential reduction in the support Kii ALS/PDC astrocytes provide to neurons, emphasizing the need to explore the role of CHCHD2 in maintaining mitochondrial health and its implications for the disease.


Asunto(s)
Esclerosis Amiotrófica Lateral , Astrocitos , Proteínas de Unión al ADN , Proteínas Mitocondriales , Factores de Transcripción , Astrocitos/patología , Astrocitos/metabolismo , Esclerosis Amiotrófica Lateral/patología , Esclerosis Amiotrófica Lateral/genética , Esclerosis Amiotrófica Lateral/metabolismo , Humanos , Proteínas de Unión al ADN/metabolismo , Proteínas de Unión al ADN/genética , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Proteínas Mitocondriales/genética , Proteínas Mitocondriales/metabolismo , Mitocondrias/patología , Mitocondrias/metabolismo , Masculino , Femenino , Persona de Mediana Edad , Anciano
7.
Neurobiol Dis ; 179: 106031, 2023 04.
Artículo en Inglés | MEDLINE | ID: mdl-36736924

RESUMEN

Organelle contact sites are multifunctional platforms for maintaining cellular homeostasis. Alternations of the mitochondria-associated membranes (MAM), one of the organelle contact sites where the endoplasmic reticulum (ER) is tethered to the mitochondria, have been involved in the pathogenesis of neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS). However, the detailed mechanisms through which MAM integrity is disrupted in ALS have not been fully elucidated. Here, we examined whether AAA ATPase domain-containing protein 3A (ATAD3A), a mitochondrial membrane AAA ATPase accumulating at the MAM, is involved in ALS. We found that sigma-1 receptor (σ1R), an ER-resident MAM protein causative for inherited juvenile ALS, required ATAD3A to maintain the MAM. In addition, σ1R retained ATAD3A as a monomer, which is associated with an inhibition of mitochondrial fragmentation. ATAD3A dimerization and mitochondrial fragmentation were significantly induced in σ1R-deficient or SOD1-linked ALS mouse spinal cords. Overall, these observations indicate that MAM induction by σ1R depends on ATAD3A and that σ1R maintains ATAD3A as a monomer to inhibit mitochondrial fragmentation. Our findings suggest that targeting σ1R-ATAD3A axis would be promising for a novel therapeutic strategy to treat mitochondrial dysfunction in neurological disorders, including ALS.


Asunto(s)
Esclerosis Amiotrófica Lateral , Enfermedades Neurodegenerativas , Ratones , Animales , Esclerosis Amiotrófica Lateral/metabolismo , Mitocondrias/metabolismo , ATPasas Asociadas con Actividades Celulares Diversas , Enfermedades Neurodegenerativas/metabolismo , Proteínas Mitocondriales/metabolismo , Receptor Sigma-1
8.
FASEB J ; 35(7): e21688, 2021 07.
Artículo en Inglés | MEDLINE | ID: mdl-34143516

RESUMEN

The mitochondria-associated membrane (MAM) is a functional subdomain of the endoplasmic reticulum membrane that tethers to the mitochondrial outer membrane and is essential for cellular homeostasis. A defect in MAM is involved in various neurological diseases, including amyotrophic lateral sclerosis (ALS). Recently, we and others reported that MAM was disrupted in the models expressing several ALS-linked genes, including SOD1, SIGMAR1, VAPB, TARDBP, and FUS, suggesting that MAM disruption is deeply involved in the pathomechanism of ALS. However, it is still uncertain whether MAM disruption is a common pathology in ALS, mainly due to the absence of a simple, quantitative tool for monitoring the status of MAM. In this study, to examine the effects of various ALS-causative genes on MAM, we created the following two novel MAM reporters: MAMtracker-Luc and MAMtracker-Green. The MAMtrackers could detect MAM disruption caused by suppression of SIGMAR1 or the overexpression of ALS-linked mutant SOD1 in living cells. Moreover, the MAMtrackers have an advantage in their ability to monitor reversible changes in the MAM status induced by nutritional conditions. We used the MAMtrackers with an expression plasmid library of ALS-causative genes and noted that 76% (16/21) of the genes altered MAM integrity. Our results suggest that MAM disruption is a common pathological feature in ALS. Furthermore, we anticipate our MAMtrackers, which are suitable for high-throughput assays, to be valuable tools to understand MAM dynamics.


Asunto(s)
Esclerosis Amiotrófica Lateral/patología , Mitocondrias/patología , Membranas Mitocondriales/patología , Proteínas Mitocondriales/metabolismo , Mutación , Neuroblastoma/patología , Esclerosis Amiotrófica Lateral/etiología , Esclerosis Amiotrófica Lateral/metabolismo , Animales , Humanos , Ratones , Mitocondrias/metabolismo , Membranas Mitocondriales/metabolismo , Proteínas Mitocondriales/genética , Neuroblastoma/genética , Neuroblastoma/metabolismo
9.
J Neurochem ; 145(1): 80-89, 2018 04.
Artículo en Inglés | MEDLINE | ID: mdl-29282717

RESUMEN

Cystatin C (CysC) is a major protein component of Bunina bodies, which are a pathological hallmark observed in the remaining motor neurons of patients with amyotrophic lateral sclerosis (ALS). Dominant mutations in the SOD1 gene, encoding Cu/Zn superoxide dismutase (SOD1), are causative for a subset of inherited ALS cases. Our previous study showed that CysC exerts a neuroprotective effect against mutant SOD1-mediated toxicity in vitro; however, in vivo evidence of the beneficial effects mediated by CysC remains obscure. Here we examined the therapeutic potential of recombinant human CysC in vivo using a mouse model of ALS in which the ALS-linked mutated SOD1 gene is expressed (SOD1G93A mice). Intracerebroventricular administration of CysC during the early symptomatic SOD1G93A mice extended their survival times. Administered CysC was predominantly distributed in ventral horn neurons including motor neurons, and induced autophagy through AMP-activated kinase activation to reduce the amount of insoluble mutant SOD1 species. Moreover, PGC-1α, a disease modifier of ALS, was restored by CysC through AMP-activated kinase activation. Finally, the administration of CysC also promoted aggregation of CysC in motor neurons, which is similar to Bunina bodies. Taken together, our findings suggest that CysC represents a promising therapeutic candidate for ALS.


Asunto(s)
Esclerosis Amiotrófica Lateral , Cistatina C/farmacología , Neuronas Motoras/efectos de los fármacos , Fármacos Neuroprotectores/farmacología , Animales , Autofagia/efectos de los fármacos , Modelos Animales de Enfermedad , Femenino , Humanos , Masculino , Ratones , Ratones Transgénicos , Mutación , Proteínas Recombinantes/farmacología , Superóxido Dismutasa-1/genética
10.
Biochim Biophys Acta Mol Basis Dis ; 1864(6 Pt A): 2119-2130, 2018 06.
Artículo en Inglés | MEDLINE | ID: mdl-29551730

RESUMEN

Dominant mutations in the gene encoding copper and zinc-binding superoxide dismutase (SOD1) cause amyotrophic lateral sclerosis (ALS). Abnormal accumulation of misfolded SOD1 proteins in spinal motoneurons is a major pathological hallmark in SOD1-related ALS. Dissociation of copper and/or zinc ions from SOD1 has been shown to trigger the protein aggregation/oligomerization in vitro, but the pathological contribution of such metal dissociation to the SOD1 misfolding still remains obscure. Here, we tested the relevance of the metal-deficient SOD1 in the misfolding in vivo by developing a novel antibody (anti-apoSOD), which exclusively recognized mutant SOD1 deficient in metal ions at its copper-binding site. Notably, anti-apoSOD-reactive species were detected specifically in the spinal cords of the ALS model mice only at their early pre-symptomatic stages but not at the end stage of the disease. The cerebrospinal fluid as well as the spinal cord homogenate of one SOD1-ALS patient also contained the anti-apoSOD-reactive species. Our results thus suggest that metal-deficiency in mutant SOD1 at its copper-binding site is one of the earliest pathological features in SOD1-ALS.


Asunto(s)
Esclerosis Amiotrófica Lateral/diagnóstico , Cobre/metabolismo , Agregación Patológica de Proteínas/diagnóstico , Superóxido Dismutasa-1/metabolismo , Adulto , Anciano , Anciano de 80 o más Años , Esclerosis Amiotrófica Lateral/genética , Esclerosis Amiotrófica Lateral/inmunología , Esclerosis Amiotrófica Lateral/patología , Animales , Anticuerpos/inmunología , Enfermedades Asintomáticas , Sitios de Unión/genética , Modelos Animales de Enfermedad , Femenino , Humanos , Masculino , Ratones , Ratones Transgénicos , Persona de Mediana Edad , Neuronas Motoras/patología , Mutación , Agregación Patológica de Proteínas/genética , Agregación Patológica de Proteínas/inmunología , Agregación Patológica de Proteínas/patología , Unión Proteica/genética , Pliegue de Proteína , Sensibilidad y Especificidad , Médula Espinal/citología , Médula Espinal/patología , Superóxido Dismutasa-1/genética , Superóxido Dismutasa-1/inmunología , Zinc/metabolismo
11.
J Cell Biochem ; 118(5): 1014-1027, 2017 05.
Artículo en Inglés | MEDLINE | ID: mdl-27487200

RESUMEN

Diclofenac is the most commonly used phenylacetic acid derivative non-steroidal anti-inflammatory drug (NSAID) that demonstrates significant analgesic, antipyretic, and anti-inflammatory effects. Several epidemiological studies have demonstrated anti-proliferative activity of NSAIDs and examined their apoptotic induction effects in different cancer cell lines. However, the precise molecular mechanisms by which these pharmacological agents induce apoptosis and exert anti-carcinogenic properties are not well known. Here, we have observed that diclofenac treatment induces proteasome malfunction and promotes accumulation of different critical proteasome substrates, including few pro-apoptotic proteins in cells. Exposure of diclofenac consequently elevates aggregation of various ubiquitylated misfolded proteins. Finally, we have shown that diclofenac treatment promotes apoptosis in cells, which could be because of mitochondrial membrane depolarization and cytochrome c release into cytosol. This study suggests possible beneficial insights of NSAIDs-induced apoptosis that may improve our existing knowledge in anti-proliferative interspecific strategies development. J. Cell. Biochem. 118: 1014-1027, 2017. © 2016 Wiley Periodicals, Inc.


Asunto(s)
Antiinflamatorios no Esteroideos/farmacología , Antineoplásicos/farmacología , Diclofenaco/farmacología , Mitocondrias/efectos de los fármacos , Complejo de la Endopetidasa Proteasomal/efectos de los fármacos , Células A549 , Animales , Apoptosis , Células COS , Supervivencia Celular/efectos de los fármacos , Chlorocebus aethiops , Potencial de la Membrana Mitocondrial/efectos de los fármacos
12.
Proc Natl Acad Sci U S A ; 111(11): 4309-14, 2014 Mar 18.
Artículo en Inglés | MEDLINE | ID: mdl-24591609

RESUMEN

Over the last two decades many secrets of the age-related human neural proteinopathies have been revealed. A common feature of these diseases is abnormal, and possibly pathogenic, aggregation of specific proteins in the effected tissue often resulting from inherent or decreased structural stability. An archetype example of this is superoxide dismutase-1, the first genetic factor to be linked with amyotrophic lateral sclerosis (ALS). Mutant or posttranslationally modified TAR DNA binding protein-32 (TDP-43) is also strongly associated with ALS and an increasingly large number of other neurodegenerative diseases, including frontotemporal lobar degeneration (FTLD). Cytoplasmic mislocalization and elevated half-life is a characteristic of mutant TDP-43. Furthermore, patient age at the onset of disease symptoms shows a good inverse correlation with mutant TDP-43 half-life. Here we show that ALS and FTLD-associated TDP-43 mutations in the central nucleic acid binding domains lead to elevated half-life and this is commensurate with increased thermal stability and inhibition of aggregation. It is achieved without impact on secondary, tertiary, or quaternary structure. We propose that tighter structural cohesion contributes to reduced protein turnover, increasingly abnormal proteostasis and, ultimately, faster onset of disease symptoms. These results contrast our perception of neurodegenerative diseases as misfolded proteinopathies and delineate a novel path from the molecular characteristics of mutant TDP-43 to aberrant cellular effects and patient phenotype.


Asunto(s)
Proteínas de Unión al ADN/genética , Enfermedades Neurodegenerativas/epidemiología , Enfermedades Neurodegenerativas/genética , Fluorescencia , Semivida , Humanos , Mutación/genética , Enfermedades Neurodegenerativas/fisiopatología , Estabilidad Proteica , Dispersión del Ángulo Pequeño
13.
Neurobiol Dis ; 86: 16-28, 2016 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-26607786

RESUMEN

Proteotoxicity of misfolded, disease-causing proteins is deeply implicated in the pathomechanisms for neurodegenerative diseases including copper-zinc superoxide dismutase (SOD1)-linked amyotrophic lateral sclerosis (ALS). However, the precise cellular quality control (QC) mechanisms against aggregation of misfolded mutant SOD1 proteins remain elusive. Here, we found that the Mahogunin ring finger-1 (MGRN1) E3 ubiquitin ligase, which catalyzes mono-ubiquitination to the substrate, was dysregulated in the cellular and mouse models of ALS and that it preferentially interacted with various mutant forms of SOD1. Intriguingly, the motor neurons of presymptomatic ALS mice have diminished MGRN1 cytoplasmic distribution. MGRN1 was partially recruited to mutant SOD1 inclusions where they were positive for p62 and Lamp2. Moreover, overexpression of MGRN1 reduced mutant SOD1 aggregation and alleviated its proteotoxic effects on cells. Taken together, our findings suggest that MGRN1 contributes to the clearance of toxic mutant SOD1 inclusions likely through autophagic pathway, and, most likely, the sequestration of MGRN1 sensitizes motor neurons to degeneration in the ALS mouse model. Furthermore, the present study identifies the MGRN1-mediated protein QC mechanism as a novel therapeutic target in neurodegenerative diseases.


Asunto(s)
Esclerosis Amiotrófica Lateral/enzimología , Esclerosis Amiotrófica Lateral/patología , Neuronas Motoras/metabolismo , Neuronas Motoras/patología , Superóxido Dismutasa/metabolismo , Ubiquitina-Proteína Ligasas/metabolismo , Animales , Células COS , Supervivencia Celular , Chlorocebus aethiops , Modelos Animales de Enfermedad , Células HEK293 , Humanos , Ratones , Ratones Transgénicos , Médula Espinal/metabolismo , Médula Espinal/patología , Superóxido Dismutasa/genética , Superóxido Dismutasa-1
14.
J Biol Chem ; 289(2): 1192-202, 2014 Jan 10.
Artículo en Inglés | MEDLINE | ID: mdl-24280224

RESUMEN

Dominant mutations in FUS/TLS cause a familial form of amyotrophic lateral sclerosis (fALS), where abnormal accumulation of mutant FUS proteins in cytoplasm has been observed as a major pathological change. Many of pathogenic mutations have been shown to deteriorate the nuclear localization signal in FUS and thereby facilitate cytoplasmic mislocalization of mutant proteins. Several other mutations, however, exhibit no effects on the nuclear localization of FUS in cultured cells, and their roles in the pathomechanism of fALS remain obscure. Here, we show that a pathogenic mutation, G156E, significantly increases the propensities for aggregation of FUS in vitro and in vivo. Spontaneous in vitro formation of amyloid-like fibrillar aggregates was observed in mutant but not wild-type FUS, and notably, those fibrils functioned as efficient seeds to trigger the aggregation of wild-type protein. In addition, the G156E mutation did not disturb the nuclear localization of FUS but facilitated the formation of intranuclear inclusions in rat hippocampal neurons with significant cytotoxicity. We thus propose that intranuclear aggregation of FUS triggered by a subset of pathogenic mutations is an alternative pathomechanism of FUS-related fALS diseases.


Asunto(s)
Esclerosis Amiotrófica Lateral/metabolismo , Núcleo Celular/metabolismo , Mutación , Proteína FUS de Unión a ARN/metabolismo , Secuencia de Aminoácidos , Sustitución de Aminoácidos , Amiloide/química , Amiloide/metabolismo , Amiloide/ultraestructura , Esclerosis Amiotrófica Lateral/genética , Animales , Línea Celular Tumoral , Células Cultivadas , Electroforesis en Gel de Poliacrilamida , Glutatión Transferasa/genética , Glutatión Transferasa/metabolismo , Humanos , Microscopía Confocal , Microscopía Electrónica , Neuronas/citología , Neuronas/metabolismo , Desnaturalización Proteica , Proteína FUS de Unión a ARN/química , Proteína FUS de Unión a ARN/genética , Ratas , Proteínas Recombinantes de Fusión/química , Proteínas Recombinantes de Fusión/genética , Proteínas Recombinantes de Fusión/metabolismo
15.
Nagoya J Med Sci ; 77(4): 537-49, 2015 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-26663933

RESUMEN

Increasing evidence suggests that the pathogenesis of neurodegenerative diseases including amyotrophic lateral sclerosis (ALS) is not restricted to the neurons but attributed to the abnormal interactions of neurons and surrounding glial and lymphoid cells. These findings led to the concept of non-cell autonomous neurodegeneration. Neuroinflammation, which is mediated by activated glial cells and infiltrated lymphocytes and accompanied by the subsequent production of proinflammatory cytokines and neurotoxic or neuroprotective molecules, is characteristic to the pathology in ALS and is a key component for non-cell autonomous neurodegeneration. This review covers the involvement of microglia and astrocytes in the ALS mouse models and human ALS, and it also covers the deregulated pathways in motor neurons, which are involved in initiating the disease. Based on the cell-type specific pathomechanisms of motor neuron disease, targeting of neuroinflammation could lead to future therapeutic strategies for ALS and could be potentially applied to other neurodegenerative diseases.

16.
J Biol Chem ; 288(7): 4970-80, 2013 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-23264618

RESUMEN

Dominant mutations in Cu,Zn-superoxide dismutase (SOD1) are a cause of a familial form of amyotrophic lateral sclerosis. Wild-type SOD1 forms a highly conserved intra-molecular disulfide bond, whereas pathological SOD1 proteins are cross-linked via intermolecular disulfide bonds and form insoluble oligomers. A thiol-disulfide status in SOD1 will thus play a regulatory role in determining its folding/misfolding pathways; however, it remains unknown how pathogenic mutations in SOD1 affect the thiol-disulfide status to facilitate the protein misfolding. Here, we show that the structural destabilization of SOD1 scrambles a disulfide bond among four Cys residues in an SOD1 molecule. The disulfide scrambling produces SOD1 monomers with distinct electrophoretic mobility and also reproduces the formation of disulfide-linked oligomers. We have also found that the familial form of amyotrophic lateral sclerosis-causing mutations facilitate the disulfide scrambling in SOD1. Based upon our results, therefore, scrambling of the conserved disulfide bond will be a key event to cause the pathological changes in disease-associated mutant SOD1 proteins.


Asunto(s)
Esclerosis Amiotrófica Lateral/metabolismo , Disulfuros/química , Regulación de la Expresión Génica , Mutación , Superóxido Dismutasa/metabolismo , Reactivos de Enlaces Cruzados/farmacología , Cisteína/química , Relación Dosis-Respuesta a Droga , Humanos , Cinética , Espectrometría de Masas/métodos , Modelos Biológicos , Desnaturalización Proteica , Pliegue de Proteína , Compuestos de Sulfhidrilo/química , Temperatura , Factores de Tiempo
17.
J Biol Chem ; 288(5): 3641-54, 2013 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-23235148

RESUMEN

Abnormal protein accumulation is a pathological hallmark of neurodegenerative diseases, including accumulation of TAR DNA-binding protein 43 (TDP-43) in amyotrophic lateral sclerosis (ALS). Dominant mutations in the TDP-43 gene are causative for familial ALS; however, the relationship between mutant protein biochemical phenotypes and disease course and their significance to disease pathomechanism are not known. Here, we found that longer half-lives of mutant proteins correlated with accelerated disease onset. Based on our findings, we established a cell model in which chronic stabilization of wild-type TDP-43 protein provoked cytotoxicity and recapitulated pathogenic protein cleavage and insolubility to the detergent Sarkosyl, TDP-43 properties that have been observed in sporadic ALS lesions. Furthermore, these cells showed proteasomal impairment and dysregulation of their own mRNA levels. These results suggest that chronically increased stability of mutant or wild-type TDP-43 proteins results in a gain of toxicity through abnormal proteostasis.


Asunto(s)
Esclerosis Amiotrófica Lateral/genética , Esclerosis Amiotrófica Lateral/patología , Proteínas de Unión al ADN/genética , Proteínas Mutantes/metabolismo , Mutación/genética , Adulto , Edad de Inicio , Anciano , Secuencia de Aminoácidos , Animales , Muerte Celular/efectos de los fármacos , Núcleo Celular/efectos de los fármacos , Núcleo Celular/metabolismo , Proteínas de Unión al ADN/química , Proteínas de Unión al ADN/metabolismo , Detergentes/farmacología , Exones/genética , Regulación de la Expresión Génica/efectos de los fármacos , Humanos , Ratones , Persona de Mediana Edad , Datos de Secuencia Molecular , Complejo de la Endopetidasa Proteasomal/metabolismo , Estabilidad Proteica/efectos de los fármacos , Transporte de Proteínas/efectos de los fármacos , ARN Mensajero/genética , ARN Mensajero/metabolismo , Solubilidad , Fracciones Subcelulares/efectos de los fármacos , Fracciones Subcelulares/metabolismo , Factores de Tiempo
18.
Brain ; 136(Pt 5): 1371-82, 2013 May.
Artículo en Inglés | MEDLINE | ID: mdl-23449777

RESUMEN

Amyotrophic lateral sclerosis is a devastating, progressive neurodegenerative disease that affects upper and lower motor neurons. Although several genes are identified as the cause of familial cases, the pathogeneses of sporadic forms, which account for 90% of amyotrophic lateral sclerosis, have not been elucidated. Transactive response DNA-binding protein 43 a nuclear protein regulating RNA processing, redistributes to the cytoplasm and forms aggregates, which are the histopathological hallmark of sporadic amyotrophic lateral sclerosis, in affected motor neurons, suggesting that loss-of-function of transactive response DNA-binding protein 43 is one of the causes of the neurodegeneration. To test this hypothesis, we assessed the effects of knockout of transactive response DNA-binding protein 43 in mouse postnatal motor neurons using Cre/loxp system. These mice developed progressive weight loss and motor impairment around the age of 60 weeks, and exhibited degeneration of large motor axon, grouped atrophy of the skeletal muscle, and denervation in the neuromuscular junction. The spinal motor neurons lacking transactive response DNA-binding protein 43 were not affected for 1 year, but exhibited atrophy at the age of 100 weeks; whereas, extraocular motor neurons, that are essentially resistant in amyotrophic lateral sclerosis, remained preserved even at the age of 100 weeks. Additionally, ultra structural analysis revealed autolysosomes and autophagosomes in the cell bodies and axons of motor neurons of the 100-week-old knockout mice. In summary, the mice in which transactive response DNA-binding protein 43 was knocked-out specifically in postnatal motor neurons exhibited an age-dependent progressive motor dysfunction accompanied by neuropathological alterations, which are common to sporadic amyotrophic lateral sclerosis. These findings suggest that transactive response DNA-binding protein 43 plays an essential role in the long term maintenance of motor neurons and that loss-of-function of this protein seems to contribute to the pathogenesis of amyotrophic lateral sclerosis.


Asunto(s)
Proteínas de Unión al ADN/deficiencia , Progresión de la Enfermedad , Neuronas Motoras/metabolismo , Neuronas Motoras/patología , Degeneración Nerviosa/metabolismo , Factores de Edad , Esclerosis Amiotrófica Lateral/metabolismo , Esclerosis Amiotrófica Lateral/patología , Esclerosis Amiotrófica Lateral/fisiopatología , Animales , Proteínas de Unión al ADN/genética , Modelos Animales de Enfermedad , Humanos , Ratones , Ratones de la Cepa 129 , Ratones Endogámicos C57BL , Ratones Noqueados , Degeneración Nerviosa/patología , Degeneración Nerviosa/fisiopatología
19.
FEBS Open Bio ; 14(2): 194-216, 2024 02.
Artículo en Inglés | MEDLINE | ID: mdl-37330425

RESUMEN

Alzheimer's disease (AD) is the most common cause of dementia. A genome-wide association study has shown that several AD risk genes are involved in lipid metabolism. Additionally, epidemiological studies have indicated that the levels of several lipid species are altered in the AD brain. Therefore, lipid metabolism is likely changed in the AD brain, and these alterations might be associated with an exacerbation of AD pathology. Oligodendrocytes are glial cells that produce the myelin sheath, which is a lipid-rich insulator. Dysfunctions of the myelin sheath have been linked to white matter abnormalities observed in the AD brain. Here, we review the lipid composition and metabolism in the brain and myelin and the association between lipidic alterations and AD pathology. We also present the abnormalities in oligodendrocyte lineage cells and white matter observed in AD. Additionally, we discuss metabolic disorders, including obesity, as AD risk factors and the effects of obesity and dietary intake of lipids on the brain.


Asunto(s)
Enfermedad de Alzheimer , Sustancia Blanca , Humanos , Enfermedad de Alzheimer/metabolismo , Sustancia Blanca/metabolismo , Sustancia Blanca/patología , Metabolismo de los Lípidos , Estudio de Asociación del Genoma Completo , Oligodendroglía , Encéfalo/metabolismo , Lípidos , Obesidad/metabolismo
20.
FEBS Open Bio ; 14(2): 162-164, 2024 02.
Artículo en Inglés | MEDLINE | ID: mdl-38217066

RESUMEN

Koji Yamanaka is a Professor at the Research Institute of Environmental Medicine at Nagoya University of Japan. His research interests lie in understanding the mechanism of onset and progression of motor neuron disease as well as the role of glial cells in Alzheimer's disease neuroinflammation. Koji has been serving on the FEBS Open Bio Editorial Board since 2013. In this interview, he explains the implications of recent findings in neurobiology for amyotrophic lateral sclerosis, provides updates on the research environment in Japan and discusses how editors might use their position to positively influence academic culture.


Asunto(s)
Esclerosis Amiotrófica Lateral , Humanos , Masculino , Esclerosis Amiotrófica Lateral/genética
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