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1.
Lancet Gastroenterol Hepatol ; 7(7): 648-657, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-35366419

RESUMO

BACKGROUND: AJM300 is an oral, small-molecule α4-integrin antagonist. We assessed the efficacy and safety of AJM300 in patients with moderately active ulcerative colitis. METHODS: This multicentre, randomised, double-blind, placebo-controlled, phase 3 study consisted of two phases: a treatment phase and an open-label re-treatment phase. The study was done at 82 hospitals and clinics in Japan. Patients with a Mayo Clinic score of 6-10, endoscopic subscore of 2 or more, rectal bleeding subscore of 1 or more, and an inadequate response or intolerance to mesalazine were enrolled. Patients were randomly allocated (1:1) via a website to either AJM300 (960 mg) or placebo by the minimisation method, which was adjusted centrally by dynamic assignment against the Mayo Clinic score (≥6 to ≤7, ≥8 to ≤10 points), any use of corticosteroid, anti-TNFα antibody, or immunosuppressants during the disease-active period (yes vs no), duration of induction therapy until randomisation (<4 weeks vs ≥4 weeks) as the minimisation factors. Patients, investigators, site staff, assessors, and the sponsor were masked to treatment assignments. The study drug was administered orally, three times daily, for 8 weeks, and continued for up to 24 weeks if endoscopic remission was not achieved or rectal bleeding did not stop. The primary endpoint was the proportion of patients with a clinical response at week 8, and was analysed in the full analysis set. Clinical response was defined as a reduction in Mayo Clinic score of 30% or more and 3 or more, a reduction in rectal bleeding score of 1 or more or rectal bleeding subscore of 1 or less, and an endoscopic subscore of 1 or less at week 8. The study is registered with ClinicalTrials.gov, NCT03531892, and is closed to recruitment. FINDINGS: Between June 6, 2018, and July 22, 2020, 203 patients were randomly assigned to AJM300 (n=102) or placebo (n=101). At week 8, 46 (45%) patients in the AJM300 group and 21 (21%) patients in the placebo group had a clinical response (odds ratio 3·30, 95% CI 1·73-6·29; p=0·00028). During the 8-week treatment and 16-week extension treatment periods, adverse events occurred in 39 (39%) of 101 patients in the placebo group and 39 (38%) of 102 patients in the AJM300 group. We found no difference in the incidence of adverse events between groups or after repeated administration of AJM300. The most common adverse event was nasopharyngitis (11 [11%] of 101 patients in the placebo group and ten [10%] of 102 patients in the AJM300 group). The most common treatment-related adverse event was also nasopharyngitis (four [4%] of 101 patients in the placebo group and three [3%] of 102 patients in the AJM300 group). Most adverse events were mild-to-moderate in severity. No deaths were reported. A serious adverse event was reported in the AJM300 group (one patient with anal abscess), but this was judged to be unrelated to study drug. INTERPRETATION: AJM300 was well tolerated and induced a clinical response in patients with moderately active ulcerative colitis who had an inadequate response or intolerance to mesalazine. AJM300 could be a novel induction therapy for the treatment of patients with moderately active ulcerative colitis. FUNDING: EA Pharma and Kissei Pharmaceutical. TRANSLATION: For the Japanese translation of the abstract see Supplementary Materials section.


Assuntos
Colite Ulcerativa , Nasofaringite , Colite Ulcerativa/tratamento farmacológico , Humanos , Quimioterapia de Indução/métodos , Integrina alfa4/antagonistas & inibidores , Mesalamina/efeitos adversos , Fenilalanina/análogos & derivados , Quinazolinonas , Resultado do Tratamento
2.
J Neurol Neurosurg Psychiatry ; 91(11): 1158-1165, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-32839349

RESUMO

OBJECTIVE: To clinically diagnose MM2-cortical (MM2C) and MM2-thalamic (MM2T)-type sporadic Creutzfeldt-Jakob disease (sCJD) at early stage with high sensitivity and specificity. METHODS: We reviewed the results of Creutzfeldt-Jakob disease Surveillance Study in Japan between April 1999 and September 2019, which included 254 patients with pathologically confirmed prion diseases, including 9 with MM2C-type sCJD (MM2C-sCJD) and 10 with MM2T-type sCJD (MM2T-sCJD), and 607 with non-prion diseases. RESULTS: According to the conventional criteria of sCJD, 4 of 9 patients with MM2C- and 7 of 10 patients with MM2T-sCJD could not be diagnosed with probable sCJD until their death. Compared with other types of sCJD, patients with MM2C-sCJD showed slower progression of the disease and cortical distribution of hyperintensity lesions on diffusion-weighted images of brain MRI. Patients with MM2T-sCJD also showed relatively slow progression and negative results for most of currently established investigations for diagnosis of sCJD. To clinically diagnose MM2C-sCJD, we propose the new criteria; diagnostic sensitivity and specificity to distinguish 'probable' MM2C-sCJD from other subtypes of sCJD, genetic or acquired prion diseases and non-prion disease controls were 77.8% and 98.5%, respectively. As for MM2T-sCJD, clinical and laboratory features are not characterised enough to develop its diagnostic criteria. CONCLUSIONS: MM2C-sCJD can be diagnosed at earlier stage using the new criteria with high sensitivity and specificity, although it is still difficult to diagnose MM2T-sCJD clinically.


Assuntos
Córtex Cerebral/diagnóstico por imagem , Circulação Cerebrovascular , Síndrome de Creutzfeldt-Jakob/diagnóstico por imagem , Proteínas PrPSc/líquido cefalorraquidiano , Proteínas Priônicas/genética , Tálamo/diagnóstico por imagem , Adulto , Idoso , Idoso de 80 Anos ou mais , Estudos de Casos e Controles , Córtex Cerebral/fisiopatologia , Síndrome de Creutzfeldt-Jakob/líquido cefalorraquidiano , Síndrome de Creutzfeldt-Jakob/genética , Síndrome de Creutzfeldt-Jakob/fisiopatologia , Cisteína/análogos & derivados , Imagem de Difusão por Ressonância Magnética , Progressão da Doença , Feminino , Fluordesoxiglucose F18 , Humanos , Iofetamina , Masculino , Pessoa de Meia-Idade , Compostos de Organotecnécio , Compostos Radiofarmacêuticos , Sensibilidade e Especificidade , Tálamo/fisiopatologia , Tomografia Computadorizada de Emissão de Fóton Único
3.
J Alzheimers Dis ; 70(3): 937-952, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31227651

RESUMO

Soluble amyloid-ß (Aß) oligomers (AßOs), which elicit neurotoxicity and synaptotoxicity, are thought to play an initiating role in the pathology of Alzheimer's disease (AD). Since AßOs are a key therapeutic target, we attempted to identify natural agents that reduce AßO neurotoxicity. Using an assay system in which primary cultured neurons are treated with AßOs, we found that Rhodiola rosea extracts and one of its main constituents, tyrosol, significantly inhibited AßO-induced caspase-3 activation. We then assessed the in vivo efficacy of tyrosol by oral administration of the compound into AD model (5XFAD) transgenic and non-transgenic mice from either 2 or 4 to 7 months of age. In both paradigms, tyrosol treatment did not affect body weights of mice. Immunohistochemical analysis revealed that the immunoreactivity of spinophilin, a dendritic synaptic protein, was significantly reduced in three hippocampal subregions of vehicle-treated AD mice compared with non-transgenic mice, which was reversed in tyrosol-treated AD mice. Tyrosol treatment also prevented the enhancement of 4-hydroxy-2-nonenal immunoreactivity in the hippocampal CA3 region of AD mice. By contrast, tyrosol administration did not affect Aß accumulation, as evaluated by immunohistochemical and biochemical analyses. Moreover, the Barnes maze test showed that tyrosol administration modestly mitigated spatial memory impairment in AD mice. These findings collectively indicate that the natural agent tyrosol protects neurons against AßO neurotoxicity in vitro and ameliorates synaptic disturbance, oxidative stress responses, and cognitive impairment in vivo. We thus suggest that tyrosol is potentially an effective, safe, and unique drug candidate for AD.


Assuntos
Doença de Alzheimer , Peptídeos beta-Amiloides/metabolismo , Caspase 3/metabolismo , Disfunção Cognitiva , Álcool Feniletílico/análogos & derivados , Rhodiola , Doença de Alzheimer/tratamento farmacológico , Doença de Alzheimer/metabolismo , Animais , Antioxidantes/farmacologia , Células Cultivadas , Disfunção Cognitiva/tratamento farmacológico , Disfunção Cognitiva/metabolismo , Modelos Animais de Doenças , Humanos , Camundongos , Proteínas dos Microfilamentos/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Neurônios/metabolismo , Neurotoxinas/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Álcool Feniletílico/farmacologia , Extratos Vegetais/farmacologia
4.
J Neurol Sci ; 373: 27-30, 2017 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-28131204

RESUMO

Gerstmann-Sträussler-Scheinker syndrome caused by the P102L mutation in the prion protein gene (GSS102) is usually characterized by the onset of slowly progressive cerebellar ataxia, with dementia occurring much later. Because of the relatively long disease course and the prominence of progressive cerebellar ataxia in the early stage, GSS102 is often misdiagnosed as other neurodegenerative disorders. We present two cases of genetically proven GSS102L, both of which present with atrophy and decreased blood flow of the thalamus as determined by voxel-based specific regional analysis system for Alzheimer's disease (VSRAD) advance software and easy Z-score analysis for 99mTc-ethyl cysteinate dimer-SPECT, respectively. These thalamic abnormalities have not been fully evaluated to date, and detecting them might be useful for differentiating GSS102 from other neurodegenerative disorders.


Assuntos
Doença de Gerstmann-Straussler-Scheinker/diagnóstico por imagem , Doença de Gerstmann-Straussler-Scheinker/genética , Imageamento por Ressonância Magnética , Proteínas Priônicas/genética , Tálamo/diagnóstico por imagem , Tomografia Computadorizada de Emissão de Fóton Único , Idoso , Cisteína/análogos & derivados , Feminino , Humanos , Interpretação de Imagem Assistida por Computador , Pessoa de Meia-Idade , Mutação , Compostos de Organotecnécio , Compostos Radiofarmacêuticos
5.
Nat Commun ; 6: 7969, 2015 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-26258894

RESUMO

Antisense oligonucleotides (ASOs) are recognized therapeutic agents for the modulation of specific genes at the post-transcriptional level. Similar to any medical drugs, there are opportunities to improve their efficacy and safety. Here we develop a short DNA/RNA heteroduplex oligonucleotide (HDO) with a structure different from double-stranded RNA used for short interfering RNA and single-stranded DNA used for ASO. A DNA/locked nucleotide acid gapmer duplex with an α-tocopherol-conjugated complementary RNA (Toc-HDO) is significantly more potent at reducing the expression of the targeted mRNA in liver compared with the parent single-stranded gapmer ASO. Toc-HDO also improves the phenotype in disease models more effectively. In addition, the high potency of Toc-HDO results in a reduction of liver dysfunction observed in the parent ASO at a similar silencing effect. HDO technology offers a novel concept of therapeutic oligonucleotides, and the development of this molecular design opens a new therapeutic field.


Assuntos
Inativação Gênica/fisiologia , Ácidos Nucleicos Heteroduplexes/fisiologia , Oligonucleotídeos , alfa-Tocoferol/farmacologia , Animais , Apolipoproteínas B/genética , Apolipoproteínas B/metabolismo , Sequência de Bases , Gorduras na Dieta/administração & dosagem , Gorduras na Dieta/efeitos adversos , Humanos , Hipercolesterolemia/induzido quimicamente , Macaca fascicularis , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , alfa-Tocoferol/química
6.
Intern Med ; 53(13): 1441-5, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24990337

RESUMO

We herein report the case of a 65-year-old woman who presented with the subacute onset of dementia and subsequently developed abnormal behavior and a gait disturbance. Her condition transiently improved; however, within one month, she became drowsy and poorly responsive, with limb chorea and urinary incontinence. Her history of frequently using charcoal led us to diagnose her with carbon monoxide (CO) poisoning. The findings of this case and a literature review suggest that subacute dementia due to CO poisoning recovers late, after a year or more, in patients above sixty years of age, and both hyperbaric oxygen and corticosteroid pulse therapy should be considered in such cases, even after one month.


Assuntos
Intoxicação por Monóxido de Carbono/complicações , Intoxicação por Monóxido de Carbono/diagnóstico , Demência/etiologia , Leucoencefalopatias/etiologia , Corticosteroides/uso terapêutico , Idoso , Encéfalo/diagnóstico por imagem , Encéfalo/patologia , Intoxicação por Monóxido de Carbono/terapia , Cisteína/análogos & derivados , Feminino , Marcha , Humanos , Oxigenoterapia Hiperbárica , Imageamento por Ressonância Magnética , Transtornos dos Movimentos/etiologia , Compostos de Organotecnécio , Compostos Radiofarmacêuticos , Fatores de Tempo , Tomografia Computadorizada de Emissão de Fóton Único
10.
Biochem Biophys Res Commun ; 405(2): 204-9, 2011 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-21219850

RESUMO

Systemic injections of AAV vectors generally transduce to the liver more effectively than to cardiac and skeletal muscles. The short hairpin RNA (shRNA)-expressing AAV9 (shRNA-AAV9) can also reduce target gene expression in the liver, but not enough in cardiac or skeletal muscles. Higher doses of shRNA-AAV9 required for inhibiting target genes in cardiac and skeletal muscles often results in shRNA-related toxicity including microRNA oversaturation that can induce fetal liver failure. In this study, we injected high-dose shRNA-AAV9 to neonates and efficiently silenced genes in cardiac and skeletal muscles without inducing liver toxicity. This is because AAV is most likely diluted or degraded in the liver than in cardiac or skeletal muscle during cell division after birth. We report that this systemically injected shRNA-AAV method does not induce any major side effects, such as liver dysfunction, and the dose of shRNA-AAV is sufficient for gene silencing in skeletal and cardiac muscle tissues. This novel method may be useful for generating gene knockdown in skeletal and cardiac mouse tissues, thus providing mouse models useful for analyzing diseases caused by loss-of-function of target genes.


Assuntos
Técnicas de Silenciamento de Genes/métodos , Músculo Esquelético/metabolismo , Miocárdio/metabolismo , Interferência de RNA , RNA Interferente Pequeno/genética , Animais , Dependovirus , Vetores Genéticos/administração & dosagem , Células HEK293 , Humanos , Injeções Intraperitoneais , Camundongos , Camundongos Endogâmicos ICR , Superóxido Dismutase/antagonistas & inibidores , Superóxido Dismutase/genética , Superóxido Dismutase-1
11.
Neuropathology ; 30(1): 76-83, 2010 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-19563507

RESUMO

A 57-year old man with chronic alcoholism presented with apraxia of speech and disturbance of consciousness. He had a history of gastrectomy and had been drinking alcohol. The symptoms improved with administration of thiamine, but he later developed diarrhea and delirium, and died approximately 40 days after the onset. Autopsy findings were consistent with Wernicke's encephalopathy and pellagra encephalopathy. Furthermore, laminar cortical necrosis with vacuoles and astrocytosis was found in the second and third layers of the bilateral frontal cortices, suggesting Morel's laminar sclerosis. The lesions were mainly located in the bilateral primary motor cortices. Involvement of the lower part of the left primary motor cortex may be associated with apraxia of speech in our case.


Assuntos
Apraxias/patologia , Encefalopatias/patologia , Encéfalo/patologia , Distúrbios da Fala/patologia , Alcoolismo/tratamento farmacológico , Alcoolismo/patologia , Autopsia , Doença Crônica , Evolução Fatal , Humanos , Masculino , Pessoa de Meia-Idade , Córtex Motor , Esclerose/patologia , Tiamina/uso terapêutico , Complexo Vitamínico B/uso terapêutico
12.
J Biol Chem ; 284(48): 33400-8, 2009 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-19679659

RESUMO

Increased oxidative damage is a prominent and early feature in Alzheimer disease. We previously crossed Alzheimer disease transgenic (APPsw) model mice with alpha-tocopherol transfer protein knock-out (Ttpa(-/-)) mice in which lipid peroxidation in the brain was significantly increased. The resulting double-mutant (Ttpa(-/-)APPsw) mice showed increased amyloid beta (Abeta) deposits in the brain, which was ameliorated with alpha-tocopherol supplementation. To investigate the mechanism of the increased Abeta accumulation, we here studied generation, degradation, aggregation, and efflux of Abeta in the mice. The clearance of intracerebral-microinjected (125)I-Abeta(1-40) from brain was decreased in Ttpa(-/-) mice to be compared with wild-type mice, whereas the generation of Abeta was not increased in Ttpa(-/-)APPsw mice. The activity of an Abeta-degrading enzyme, neprilysin, did not decrease, but the expression level of insulin-degrading enzyme was markedly decreased in Ttpa(-/-) mouse brain. In contrast, Abeta aggregation was accelerated in Ttpa(-/-) mouse brains compared with wild-type brains, and well known molecules involved in Abeta transport from brain to blood, low density lipoprotein receptor-related protein-1 (LRP-1) and p-glycoprotein, were up-regulated in the small vascular fraction of Ttpa(-/-) mouse brains. Moreover, the disappearance of intravenously administered (125)I-Abeta(1-40) was decreased in Ttpa(-/-) mice with reduced translocation of LRP-1 in the hepatocytes. These results suggest that lipid peroxidation due to depletion of alpha-tocopherol impairs Abeta clearances from the brain and from the blood, possibly causing increased Abeta accumulation in Ttpa(-/-)APPsw mouse brain and plasma.


Assuntos
Doença de Alzheimer/metabolismo , Peptídeos beta-Amiloides/metabolismo , Encéfalo/metabolismo , Proteínas de Transporte/metabolismo , Tocoferóis/metabolismo , Doença de Alzheimer/sangue , Doença de Alzheimer/genética , Secretases da Proteína Precursora do Amiloide/metabolismo , Peptídeos beta-Amiloides/genética , Peptídeos beta-Amiloides/farmacocinética , Animais , Barreira Hematoencefálica/efeitos dos fármacos , Barreira Hematoencefálica/metabolismo , Northern Blotting , Western Blotting , Encéfalo/efeitos dos fármacos , Proteínas de Transporte/genética , Suplementos Nutricionais , Modelos Animais de Doenças , Feminino , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , alfa-Tocoferol/administração & dosagem , alfa-Tocoferol/farmacologia
13.
Rinsho Shinkeigaku ; 48(2): 125-9, 2008 Feb.
Artigo em Japonês | MEDLINE | ID: mdl-18326306

RESUMO

We report an 81-year-old woman who suffered from theophylline-associated seizures followed by partial seizures due to vitamin B6 deficiency. She developed complex partial seizures. She had been treated with theophylline for two months because of chronic bronchitis. Brain diffusion-weighted magnetic resonance imaging (MRI) showed high intensity lesions in unilateral cerebral cortex and thalamus. Electroencephalogram presented periodic lateralized epileptiform discharges (PLEDs), and single photon emission computed tomography (SPECT) using 123I-IMP revealed increased blood flow in the same side of the cerebrum. We diagnosed as theophylline-associated seizures though blood theophylline concentration disclosed its therapeutic dose, and her symptom improved after theophylline was discontinued. She developed partial seizures again, after she suffered from diarrhea for two days. Laboratory examination showed that serum vitamin B6 was under the limitation of measurement, and intravenous supplementation of vitamin B6 stopped her seizures immediately. Theophylline may induce seizures independent of its blood concentration, and vitamin B6 deficiency may exist in the case of theophylline-associated seizures.


Assuntos
Broncodilatadores/efeitos adversos , Epilepsias Parciais/etiologia , Convulsões/induzido quimicamente , Teofilina/efeitos adversos , Deficiência de Vitamina B 6/complicações , Idoso de 80 Anos ou mais , Epilepsias Parciais/tratamento farmacológico , Feminino , Humanos , Resultado do Tratamento , Vitamina B 6/administração & dosagem , Deficiência de Vitamina B 6/tratamento farmacológico
14.
Biochem Biophys Res Commun ; 350(3): 530-6, 2006 Nov 24.
Artigo em Inglês | MEDLINE | ID: mdl-17026966

RESUMO

Increased oxidative damage is a prominent and early feature in Alzheimer disease (AD). However, whether it is a primary cause or merely a downstream consequence in AD pathology is still unknown. We previously generated alpha-tocopherol transfer protein knockout (Ttpa-/-) mice, in which lipid peroxidation in the brain was significantly increased by complete depletion of alpha-tocopherol (alpha-Toc). Here we crossed AD transgenic (APPsw) model mice (Tg2576) with Ttpa-/- mice. The resulting double-mutant (Ttpa-/- APPsw) mice showed earlier and more severe cognitive dysfunction in the Morris water maze, novel-object recognition, and contextual fear conditioning tests. They also showed increased amyloid beta-peptide (Abeta) deposits in the brain by immunohistochemical analysis, which was ameliorated with alpha-Toc supplementation. In this report we provide clear evidence indicating that chronic lipid peroxidation due to alpha-Toc depletion enhances AD phenotype in a mouse model.


Assuntos
Doença de Alzheimer/patologia , Doença de Alzheimer/fisiopatologia , Peptídeos beta-Amiloides/metabolismo , Modelos Animais de Doenças , Deficiência de Vitamina E/patologia , Deficiência de Vitamina E/fisiopatologia , Doença de Alzheimer/complicações , Animais , Encéfalo/metabolismo , Encéfalo/patologia , Transtornos Cognitivos/complicações , Transtornos Cognitivos/patologia , Transtornos Cognitivos/fisiopatologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Fenótipo , Deficiência de Vitamina E/complicações
15.
Biochem Biophys Res Commun ; 340(1): 263-7, 2006 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-16364250

RESUMO

Brain capillary endothelial cells (BCECs) play an important role in blood-brain barrier (BBB) functions and pathophysiologic mechanisms in brain ischemia and inflammation. We try to suppress gene expression in BCECs by intravenous application of small interfering RNA (siRNA). After injection of large dose siRNA with hydrodynamic technique to mouse, suppression of endogenous protein and the BBB function of BCECs was investigated. The brain-to-blood transport function of organic anion transporter 3 (OAT3) that expressed in BCECs was evaluated by Brain Efflux Index method in mouse. The siRNA could be delivered to BCECs and efficiently inhibited endogenously expressed protein of BCECs. The suppression effect of siRNA to OAT3 is enough to reduce the brain-to-blood transport of OAT3 substrate, benzylpenicillin at BBB. The in vivo siRNA-silencing method with hydrodynamic technique may be useful for the study of BBB function and gene therapy targeting BCECs.


Assuntos
Barreira Hematoencefálica/fisiologia , Encéfalo/irrigação sanguínea , Células Endoteliais/fisiologia , Inativação Gênica , Marcação de Genes/métodos , Transportadores de Ânions Orgânicos Sódio-Independentes/metabolismo , Superóxido Dismutase/metabolismo , Animais , Encéfalo/fisiologia , Linhagem Celular , Sistemas de Liberação de Medicamentos/métodos , Humanos , Rim/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos ICR , Transportadores de Ânions Orgânicos Sódio-Independentes/genética , RNA Interferente Pequeno/administração & dosagem , RNA Interferente Pequeno/genética , Superóxido Dismutase/genética , Superóxido Dismutase-1
16.
Neurosci Lett ; 341(1): 74-8, 2003 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-12676347

RESUMO

Spinocerebellar ataxia type 6 (SCA6) is a neurodegenerative disease caused by small CAG repeat expansion in the alpha1A calcium channel gene. We found that the human alpha1A calcium channel protein expressed in human embryonic kidney 293T cells produces a 75 kDa C-terminal fragment. This fragment is more toxic to cells than the full-length alpha1A calcium channel, regardless of polyglutamine tract length. In cells stably transfected with plasmids of full-length alpha1A calcium channel cDNAs, the C-terminal fragment protein is present in the mutant transformant but not in the wild-type one, indicative that this C-terminal fragment with the expanded polyglutamine tract is more resistant to proteolysis than that with the normal sized polyglutamine tract. We speculate that the toxic C-terminal fragment, in which resistance to proteolysis is rendered by the expanded polyglutamine, has a key role in the pathological mechanism of SCA6.


Assuntos
Canais de Cálcio/metabolismo , Canais de Cálcio/toxicidade , Ataxias Espinocerebelares/metabolismo , Canais de Cálcio/genética , Linhagem Celular , DNA Complementar/genética , DNA Complementar/metabolismo , Humanos , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Ataxias Espinocerebelares/genética , Transfecção/métodos , Expansão das Repetições de Trinucleotídeos/fisiologia
17.
J Biol Chem ; 277(9): 7214-21, 2002 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-11756409

RESUMO

The alpha(1)2.1 (alpha(1A)) subunits of P-type and Q-type Ca(2+) channels are encoded by a single gene, Cacna1a. Although these channels differ in the inactivation kinetics and sensitivity to omega-agatoxin IVA, the mechanism underlying these differences remains to be clarified. Alternative splicings of the Cacna1a transcript have been postulated to contribute to the respective properties, however, the splice variants responsible for P-type Ca(2+) channels have not been identified. To explore P-type-specific splice variants, we aimed at cloning alpha(1)2.1 from isolated mouse Purkinje cells using single-cell reverse transcription-PCR, because in Purkinje cells P-type currents dominate over the whole currents (>95%) with Q-type currents undetected. As a result, two novel splice variants were cloned. Compared with the previously cloned mouse alpha(1)2.1, two novel variants had additional 48 amino acids at the amino termini, six single amino acid changes, and splicing variations at the exon 46/47 boundary, which produced different carboxyl termini. Furthermore, one variant had one RNA editing site. However, electrophysiological and pharmacological studies indicated that these variants did not generate P-type current in cultured cells. These results suggest that P-type-specific splice variants may exist but that post-translational processing or modification by uncharacterized interacting proteins is also required for generating the P-type current.


Assuntos
Processamento Alternativo , Canais de Cálcio Tipo N/genética , Canais de Cálcio Tipo N/metabolismo , Cálcio/metabolismo , Células de Purkinje/metabolismo , Sequência de Aminoácidos , Aminoácidos/química , Animais , Sítios de Ligação , Linhagem Celular , Clonagem Molecular , DNA Complementar/metabolismo , Eletrofisiologia , Éxons , Humanos , Cinética , Camundongos , Camundongos Endogâmicos C57BL , Dados de Sequência Molecular , Reação em Cadeia da Polimerase , RNA/metabolismo , Ratos , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transfecção
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