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1.
Hum Mol Genet ; 22(5): 890-903, 2013 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-23197655

RESUMEN

Spinocerebellar ataxia type 7 (SCA7) is a dominantly inherited neurodegenerative disorder caused by a CAG - polyglutamine (polyQ) repeat expansion in the ataxin-7 gene. In polyQ disorders, synaptic dysfunction and neurodegeneration may develop prior to symptom onset. However, conditional expression studies of polyQ disease models demonstrate that suppression of gene expression can yield complete reversal of established behavioral abnormalities. To determine if SCA7 neurological and neurodegenerative phenotypes are reversible, we crossed PrP-floxed-SCA7-92Q BAC transgenic mice with a tamoxifen-inducible Cre recombinase transgenic line, CAGGS-Cre-ER™. PrP-floxed-SCA7-92Q BAC;CAGGS-Cre-ER™ bigenic mice were treated with a single dose of tamoxifen 1 month after the onset of detectable ataxia, which resulted in ~50% reduction of polyQ-ataxin-7 expression. Tamoxifen treatment halted or reversed SCA7 motor symptoms, reduced ataxin-7 aggregation in Purkinje cells (PCs), and prevented loss of climbing fiber (CF)-PC synapses in comparison to vehicle-treated bigenic animals and tamoxifen-treated PrP-floxed-SCA7-92Q BAC single transgenic mice. Despite this phenotype rescue, reduced ataxin-7 expression did not result in full recovery of cerebellar molecular layer thickness or prevent Bergmann glia degeneration. These results demonstrate that suppression of mutant gene expression by only 50% in a polyQ disease model can have a significant impact on disease phenotypes, even when initiated after the onset of detectable behavioral deficits. The findings reported here are consistent with the emerging view that therapies aimed at reducing neurotoxic gene expression hold the potential to halt or reverse disease progression in afflicted patients, even after the onset of neurological disability.


Asunto(s)
Locomoción , Proteínas del Tejido Nervioso/genética , Péptidos , Ataxias Espinocerebelosas/genética , Animales , Ataxina-7 , Cerebelo/citología , Cerebelo/metabolismo , Cerebelo/fisiopatología , Modelos Animales de Enfermedad , Regulación de la Expresión Génica , Humanos , Locomoción/genética , Locomoción/fisiología , Ratones , Ratones Transgénicos , Mutación , Proteínas del Tejido Nervioso/metabolismo , Péptidos/genética , Péptidos/metabolismo , Células de Purkinje/citología , Células de Purkinje/metabolismo , Células de Purkinje/patología , Ataxias Espinocerebelosas/fisiopatología , Expansión de Repetición de Trinucleótido
2.
Dis Model Mech ; 17(3)2024 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-38469687

RESUMEN

Protein homeostasis is perturbed in aging-related neurodegenerative diseases called tauopathies, which are pathologically characterized by aggregation of the microtubule-associated protein tau (encoded by the human MAPT gene). Transgenic Caenorhabditis elegans serve as a powerful model organism to study tauopathy disease mechanisms, but moderating transgenic expression level has proven problematic. To study neuronal tau proteostasis, we generated a suite of transgenic strains expressing low, medium or high levels of Dendra2::tau fusion proteins by comparing integrated multicopy transgene arrays with single-copy safe-harbor locus strains generated by recombinase-mediated cassette exchange. Multicopy Dendra2::tau strains exhibited expression level-dependent neuronal dysfunction that was modifiable by known genetic suppressors or an enhancer of tauopathy. Single-copy Dendra2::tau strains lacked distinguishable phenotypes on their own but enabled detection of enhancer-driven neuronal dysfunction. We used multicopy Dendra2::tau strains in optical pulse-chase experiments measuring tau turnover in vivo and found that Dendra2::tau turned over faster than the relatively stable Dendra2. Furthermore, Dendra2::tau turnover was dependent on the protein expression level and independent of co-expression with human TDP-43 (officially known as TARDBP), an aggregating protein interacting with pathological tau. We present Dendra2::tau transgenic C. elegans as a novel tool for investigating molecular mechanisms of tau proteostasis.


Asunto(s)
Proteínas de Caenorhabditis elegans , Proteostasis , Proteínas tau , Animales , Humanos , Animales Modificados Genéticamente , Caenorhabditis elegans/genética , Caenorhabditis elegans/metabolismo , Proteínas de Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/metabolismo , Modelos Animales de Enfermedad , Proteínas tau/genética , Proteínas tau/metabolismo , Tauopatías/metabolismo
3.
Commun Biol ; 7(1): 903, 2024 Jul 25.
Artículo en Inglés | MEDLINE | ID: mdl-39060347

RESUMEN

Pathological tau disrupts protein homeostasis (proteostasis) within neurons in Alzheimer's disease (AD) and related disorders. We previously showed constitutive activation of the endoplasmic reticulum unfolded protein response (UPRER) transcription factor XBP-1s rescues tauopathy-related proteostatic disruption in a tau transgenic Caenorhabditis elegans (C. elegans) model of human tauopathy. XBP-1s promotes clearance of pathological tau, and loss of function of the ATF-6 branch of the UPRER prevents XBP-1s rescue of tauopathy in C. elegans. We conducted transcriptomic analysis of tau transgenic and xbp-1s transgenic C. elegans and found 116 putative target genes significantly upregulated by constitutively active XBP-1s. Among these were five candidate XBP-1s target genes with human orthologs and a previously known association with ATF6 (csp-1, dnj-28, hsp-4, ckb-2, and lipl-3). We examined the functional involvement of these targets in XBP-1s-mediated tauopathy suppression and found loss of function in any one of these genes completely disrupts XBP-1s suppression of tauopathy. Further, we demonstrate upregulation of HSP-4, C. elegans BiP, partially rescues tauopathy independent of other changes in the transcriptional network. Understanding how the UPRER modulates pathological tau accumulation will inform neurodegenerative disease mechanisms and direct further study in mammalian systems with the long-term goal of identifying therapeutic targets in human tauopathies.


Asunto(s)
Animales Modificados Genéticamente , Proteínas de Caenorhabditis elegans , Caenorhabditis elegans , Tauopatías , Respuesta de Proteína Desplegada , Caenorhabditis elegans/genética , Caenorhabditis elegans/metabolismo , Animales , Proteínas de Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/metabolismo , Tauopatías/metabolismo , Tauopatías/genética , Humanos , Retículo Endoplásmico/metabolismo , Retículo Endoplásmico/genética , Proteínas tau/metabolismo , Proteínas tau/genética , Proteína 1 de Unión a la X-Box/metabolismo , Proteína 1 de Unión a la X-Box/genética , Modelos Animales de Enfermedad , Factores de Transcripción/metabolismo , Factores de Transcripción/genética , Regulación de la Expresión Génica , Proteínas Portadoras
4.
J Neurosci ; 31(45): 16269-78, 2011 Nov 09.
Artículo en Inglés | MEDLINE | ID: mdl-22072678

RESUMEN

Spinocerebellar ataxia type 7 (SCA7) is a dominantly inherited disorder characterized by cerebellum and brainstem neurodegeneration. SCA7 is caused by a CAG/polyglutamine (polyQ) repeat expansion in the ataxin-7 gene. We previously reported that directed expression of polyQ-ataxin-7 in Bergmann glia (BG) in transgenic mice leads to ataxia and non-cell-autonomous Purkinje cell (PC) degeneration. To further define the cellular basis of SCA7, we derived a conditional inactivation mouse model by inserting a loxP-flanked ataxin-7 cDNA with 92 repeats into the translational start site of the murine prion protein (PrP) gene in a bacterial artificial chromosome (BAC). The PrP-floxed-SCA7-92Q BAC mice developed neurological disease, and exhibited cerebellar degeneration and BG process loss. To inactivate polyQ-ataxin-7 expression in specific cerebellar cell types, we crossed PrP-floxed-SCA7-92Q BAC mice with Gfa2-Cre transgenic mice (to direct Cre to BG) or Pcp2-Cre transgenic mice (which yields Cre in PCs and inferior olive). Excision of ataxin-7 from BG partially rescued the behavioral phenotype, but did not prevent BG process loss or molecular layer thinning, while excision of ataxin-7 from PCs and inferior olive provided significantly greater rescue and prevented both pathological changes, revealing a non-cell-autonomous basis for BG pathology. When we prevented expression of mutant ataxin-7 in BG, PCs, and inferior olive by deriving Gfa2-Cre;Pcp2-Cre;PrP-floxed-SCA7-92Q BAC triple transgenic mice, we noted a dramatic improvement in SCA7 disease phenotypes. These findings indicate that SCA7 disease pathogenesis involves a convergence of alterations in a variety of different cell types to fully recapitulate the cerebellar degeneration.


Asunto(s)
Mutación/genética , Proteínas del Tejido Nervioso/genética , Neuronas/patología , Ataxias Espinocerebelosas/genética , Análisis de Varianza , Animales , Ataxina-7 , Modelos Animales de Enfermedad , Regulación de la Expresión Génica/genética , Humanos , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Actividad Motora/genética , Proteínas del Tejido Nervioso/metabolismo , Neuroglía/patología , Péptidos/genética , Fenotipo , Priones/genética , ARN Mensajero/metabolismo , Prueba de Desempeño de Rotación con Aceleración Constante , Ataxias Espinocerebelosas/patología , Ataxias Espinocerebelosas/fisiopatología
5.
Nat Commun ; 10(1): 4443, 2019 09 30.
Artículo en Inglés | MEDLINE | ID: mdl-31570707

RESUMEN

To endure over the organismal lifespan, neurons utilize multiple strategies to achieve protein homeostasis (proteostasis). Some homeostatic mechanisms act in a subcellular compartment-specific manner, but others exhibit trans-compartmental mechanisms of proteostasis. To identify pathways protecting neurons from pathological tau protein, we employed a transgenic Caenorhabditis elegans model of human tauopathy exhibiting proteostatic disruption. We show normal functioning of the endoplasmic reticulum unfolded protein response (UPRER) promotes clearance of pathological tau, and loss of the three UPRER branches differentially affects tauopathy phenotypes. Loss of function of xbp-1 and atf-6 genes, the two main UPRER transcription factors, exacerbates tau toxicity. Furthermore, constitutive activation of master transcription factor XBP-1 ameliorates tauopathy phenotypes. However, both ATF6 and PERK branches of the UPRER participate in amelioration of tauopathy by constitutively active XBP-1, possibly through endoplasmic reticulum-associated protein degradation (ERAD). Understanding how the UPRER modulates pathological tau accumulation will inform neurodegenerative disease mechanisms.


Asunto(s)
Retículo Endoplásmico/metabolismo , Enfermedades Neurodegenerativas/metabolismo , Respuesta de Proteína Desplegada/fisiología , Proteína 1 de Unión a la X-Box/metabolismo , Proteínas tau/metabolismo , Animales , Animales Modificados Genéticamente , Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/metabolismo , Proteínas Portadoras/genética , Proteínas Portadoras/metabolismo , Degradación Asociada con el Retículo Endoplásmico , Homeostasis , Humanos , Modelos Animales , Neuronas/metabolismo , Fenotipo , Tauopatías/metabolismo , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Proteína 1 de Unión a la X-Box/genética , eIF-2 Quinasa/metabolismo , Proteínas tau/efectos adversos
6.
Parkinsonism Relat Disord ; 63: 204-208, 2019 06.
Artículo en Inglés | MEDLINE | ID: mdl-30765263

RESUMEN

BACKGROUND: Mutations in the glucocerebrosidase (GBA) gene are an important risk factor for Parkinson's disease (PD). However, most GBA genetic studies in PD have been performed in patients of European origin and very few data are available in other populations. METHODS: We sequenced the entire GBA coding region in 602 PD patients and 319 controls from Colombia and Peru enrolled as part of the Latin American Research Consortium on the Genetics of Parkinson's disease (LARGE-PD). RESULTS: We observed a significantly higher proportion of GBA mutation carriers in patients compared to healthy controls (5.5% vs 1.6%; OR = 4.3, p = 0.004). Interestingly, the frequency of mutations in Colombian patients (9.9%) was more than two-fold greater than in Peruvian patients (4.2%) and other European-derived populations reported in the literature (4-5%). This was primarily due to the presence of a population-specific mutation (p.K198E) found only in the Colombian cohort. We also observed that the age at onset was significantly earlier in GBA carriers when compared to non-carriers (47.1 ±â€¯14.2 y vs. 55.9 ±â€¯14.2 y; p = 0.0004). CONCLUSION: These findings suggest that GBA mutations are strongly associated with PD risk and earlier age at onset in Peru and Colombia. The high frequency of GBA carriers among Colombian PD patients (∼10%) makes this population especially well-suited for novel therapeutic approaches that target GBA-related PD.


Asunto(s)
Glucosilceramidasa/genética , Enfermedad de Parkinson/epidemiología , Enfermedad de Parkinson/genética , Adolescente , Adulto , Edad de Inicio , Anciano , Anciano de 80 o más Años , Colombia/epidemiología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Perú/epidemiología , Adulto Joven
7.
Neurobiol Aging ; 35(11): 2656.e17-2656.e23, 2014 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-24973808

RESUMEN

Leucine-rich repeat kinase 2 (LRRK2) is a causative gene of autosomal dominant familial Parkinson's disease (PD). We screened for LRRK2 mutations in 3 frequently reported exons (31, 41, and 48) in our cohort of 871 Japanese patients with PD (430 with sporadic PD and 441 probands with familial PD). Direct sequencing analysis of LRRK2 revealed 1 proband (0.11%) with a p.R1441G mutation, identified for the first time in Asian countries, besides frequently reported substitutions including, the p.G2019S mutation (0.11%) and p.G2385R variant (11.37%). Several studies have suggested that the LRRK2 p.R1441G mutation, which is highly prevalent in the Basque country, is extremely rare outside of northern Spain. Further analysis of family members of the proband with the p.R1441G mutation revealed that her mother and first cousin shared the same mutation and parkinsonism. Haplotype analysis revealed a different haplotype from that of the original Spanish families. Our patients demonstrated levodopa-responsive parkinsonism with intrafamilial clinical heterogeneity. This is the first report of familial PD because of the LRRK2 p.R1441G mutation in Asia.


Asunto(s)
Pueblo Asiatico/genética , Estudios de Asociación Genética , Predisposición Genética a la Enfermedad/genética , Mutación , Enfermedad de Parkinson/genética , Proteínas Serina-Treonina Quinasas/genética , Adulto , Anciano , Estudios de Cohortes , Exones/genética , Femenino , Haplotipos , Humanos , Proteína 2 Quinasa Serina-Treonina Rica en Repeticiones de Leucina , Levodopa/uso terapéutico , Masculino , Persona de Mediana Edad , Enfermedad de Parkinson/tratamiento farmacológico , Linaje , Análisis de Secuencia de ADN
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