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1.
Autophagy ; 16(2): 347-370, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30983487

RESUMO

Parkinson disease (PD) is an age-related neurodegenerative disorder associated with misfolded SNCA/α-synuclein accumulation in brain. Impaired catabolism of SNCA potentiates formation of its toxic oligomers. LRRK2 (leucine-rich repeat kinase-2) mutations predispose to familial and sporadic PD. Mutant LRRK2 perturbs chaperone-mediated-autophagy (CMA) to degrade SNCA. We showed greater age-dependent accumulation of oligomeric SNCA in striatum and cortex of aged LRRK2R1441G knockin (KI) mice, compared to age-matched wildtype (WT) by 53% and 31%, respectively. Lysosomal clustering and accumulation of CMA-specific LAMP2A and HSPA8/HSC70 proteins were observed in aged mutant striatum along with increased GAPDH (CMA substrate) by immunohistochemistry of dorsal striatum and flow cytometry of ventral midbrain cells. Using our new reporter protein clearance assay, mutant mouse embryonic fibroblasts (MEFs) expressing either SNCA or CMA recognition 'KFERQ'-like motif conjugated with photoactivated-PAmCherry showed slower cellular clearance compared to WT by 28% and 34%, respectively. However, such difference was not observed after the 'KFERQ'-motif was mutated. LRRK2 mutant MEFs exhibited lower lysosomal degradation than WT indicating lysosomal dysfunction. LAMP2A-knockdown reduced total lysosomal activity and clearance of 'KFERQ'-substrate in WT but not in mutant MEFs, indicating impaired CMA in the latter. A CMA-specific activator, AR7, induced neuronal LAMP2A transcription and lysosomal activity in MEFs. AR7 also attenuated the progressive accumulation of both intracellular and extracellular SNCA oligomers in prolonged cultures of mutant cortical neurons (DIV21), indicating that oligomer accumulation can be suppressed by CMA activation. Activation of autophagic pathways to reduce aged-related accumulation of pathogenic SNCA oligomers is a viable disease-modifying therapeutic strategy for PD.Abbreviations: 3-MA: 3-methyladenine; AR7: 7-chloro-3-(4-methylphenyl)-2H-1,4-benzoxazine; CMA: chaperone-mediated autophagy; CQ: chloroquine; CSF: cerebrospinal fluid; DDM: n-dodecyl ß-D-maltoside; DIV: days in vitro; ELISA: enzyme-linked immunosorbent assay; FACS: fluorescence-activated cell sorting; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; GWAS: genome-wide association studies; HSPA8/HSC70: heat shock protein 8; KFERQ: CMA recognition pentapeptide; KI: knockin; LAMP1: lysosomal-associated membrane protein 1; LAMP2A: lysosomal-associated membrane protein 2A; LDH: lactate dehydrogenase; LRRK2: leucine-rich repeat kinase 2; MEF: mouse embryonic fibroblast; NDUFS4: NADH:ubiquinone oxidoreductase core subunit S4; NE: novel epitope; PD: Parkinson disease; RARA/RARα: retinoic acid receptor, alpha; SNCA: synuclein, alpha; TUBB3/TUJ1: tubulin, beta 3 class III; WT: wild-type.

2.
Transl Neurodegener ; 8: 23, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31428316

RESUMO

Background: Parkinson's disease (PD) is characterized by dopaminergic neuronal loss in the substantia nigra pars compacta and intracellular inclusions called Lewy bodies (LB). During the course of disease, misfolded α-synuclein, the major constituent of LB, spreads to different regions of the brain in a prion-like fashion, giving rise to successive non-motor and motor symptoms. Etiology is likely multifactorial, and involves interplay among aging, genetic susceptibility and environmental factors. Main body: The prevalence of PD rises exponentially with age, and aging is associated with impairment of cellular pathways which increases susceptibility of dopaminergic neurons to cell death. However, the majority of those over the age of 80 do not have PD, thus other factors in addition to aging are needed to cause disease. Discovery of neurotoxins which can result in parkinsonism led to efforts in identifying environmental factors which may influence PD risk. Nevertheless, the causality of most environmental factors is not conclusively established, and alternative explanations such as reverse causality and recall bias cannot be excluded. The lack of geographic clusters and conjugal cases also go against environmental toxins as a major cause of PD. Rare mutations as well as common variants in genes such as SNCA, LRRK2 and GBA are associated with risk of PD, but Mendelian causes collectively only account for 5% of PD and common polymorphisms are associated with small increase in PD risk. Heritability of PD has been estimated to be around 30%. Thus, aging, genetics and environmental factors each alone is rarely sufficient to cause PD for most patients. Conclusion: PD is a multifactorial disorder involving interplay of aging, genetics and environmental factors. This has implications on the development of appropriate animal models of PD which take all these factors into account. Common converging pathways likely include mitochondrial dysfunction, impaired autophagy, oxidative stress and neuroinflammation, which are associated with the accumulation and spread of misfolded α-synuclein and neurodegeneration. Understanding the mechanisms involved in the initiation and progression of PD may lead to potential therapeutic targets to prevent PD or modify its course.

3.
Biochem J ; 475(1): 1-22, 2018 01 02.
Artigo em Inglês | MEDLINE | ID: mdl-29127256

RESUMO

Mutations that activate the LRRK2 (leucine-rich repeat protein kinase 2) protein kinase predispose to Parkinson's disease, suggesting that LRRK2 inhibitors might have therapeutic benefit. Recent work has revealed that LRRK2 phosphorylates a subgroup of 14 Rab proteins, including Rab10, at a specific residue located at the centre of its effector-binding switch-II motif. In the present study, we analyse the selectivity and sensitivity of polyclonal and monoclonal phospho-specific antibodies raised against nine different LRRK2-phosphorylated Rab proteins (Rab3A/3B/3C/3D, Rab5A/5B/5C, Rab8A/8B, Rab10, Rab12, Rab29[T71], Rab29[S72], Rab35 and Rab43). We identify rabbit monoclonal phospho-specific antibodies (MJFF-pRAB10) that are exquisitely selective for LRRK2-phosphorylated Rab10, detecting endogenous phosphorylated Rab10 in all analysed cell lines and tissues, including human brain cingulate cortex. We demonstrate that the MJFF-pRAB10 antibodies can be deployed to assess enhanced Rab10 phosphorylation resulting from pathogenic (R1441C/G or G2019S) LRRK2 knock-in mutations as well as the impact of LRRK2 inhibitor treatment. We also identify rabbit monoclonal antibodies displaying broad specificity (MJFF-pRAB8) that can be utilised to assess LRRK2-controlled phosphorylation of a range of endogenous Rab proteins, including Rab8A, Rab10 and Rab35. The antibodies described in the present study will help with the assessment of LRRK2 activity and examination of which Rab proteins are phosphorylated in vivo These antibodies could also be used to assess the impact of LRRK2 inhibitors in future clinical trials.


Assuntos
Anticorpos Monoclonais/biossíntese , Anticorpos Fosfo-Específicos/biossíntese , Serina-Treonina Proteína Quinase-2 com Repetições Ricas em Leucina/genética , Mutação , Proteínas rab de Ligação ao GTP/química , Sequência de Aminoácidos , Animais , Anticorpos Monoclonais/química , Anticorpos Monoclonais/isolamento & purificação , Anticorpos Fosfo-Específicos/química , Anticorpos Fosfo-Específicos/isolamento & purificação , Especificidade de Anticorpos , Regulação da Expressão Gênica , Predisposição Genética para Doença , Giro do Cíngulo/enzimologia , Giro do Cíngulo/fisiopatologia , Humanos , Serina-Treonina Proteína Quinase-2 com Repetições Ricas em Leucina/metabolismo , Camundongos , Família Multigênica , Doença de Parkinson/enzimologia , Doença de Parkinson/genética , Doença de Parkinson/fisiopatologia , Fosforilação , Isoformas de Proteínas/química , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Coelhos , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , Transdução de Sinais , Proteínas rab de Ligação ao GTP/genética , Proteínas rab de Ligação ao GTP/metabolismo
4.
Transl Neurodegener ; 6: 27, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29046784

RESUMO

The clinical diagnosis of neurodegenerative disorders based on phenotype is difficult in heterogeneous conditions with overlapping symptoms. It does not take into account the disease etiology or the highly variable clinical course even amongst patients diagnosed with the same disorder. The advent of next generation sequencing (NGS) has allowed for a system-wide, unbiased approach to identify all gene variants in the genome simultaneously. With the plethora of new genes being identified, genetic rather than phenotype-based classification of Mendelian diseases such as spinocerebellar ataxia (SCA), hereditary spastic paraplegia (HSP) and Charcot-Marie-Tooth disease (CMT) has become widely accepted. It has also become clear that gene variants play a role in common and predominantly sporadic neurodegenerative diseases such as Parkinson's disease (PD) and amyotrophic lateral sclerosis (ALS). The observation of pleiotropy has emerged, with mutations in the same gene giving rise to diverse phenotypes, which further increases the complexity of phenotype-genotype correlation. Possible mechanisms of pleiotropy include different downstream effects of different mutations in the same gene, presence of modifier genes, and oligogenic inheritance. Future directions include development of bioinformatics tools and establishment of more extensive public genotype/phenotype databases to better distinguish deleterious gene variants from benign polymorphisms, translation of genetic findings into pathogenic mechanisms through in-vitro and in-vivo studies, and ultimately finding disease-modifying therapies for neurodegenerative disorders.

5.
Neurobiol Aging ; 58: 238.e9-238.e15, 2017 10.
Artigo em Inglês | MEDLINE | ID: mdl-28709720

RESUMO

Genetic variants are implicated in the development of amyotrophic lateral sclerosis (ALS), but it is unclear whether the burden of rare variants in ALS genes has an effect on survival. We performed whole genome sequencing on 8 familial ALS (FALS) patients with superoxide dismutase 1 (SOD1) mutation and whole exome sequencing on 46 sporadic ALS (SALS) patients living in Hong Kong and found that 67% had at least 1 rare variant in the exons of 40 ALS genes; 22% had 2 or more. Patients with 2 or more rare variants had lower probability of survival than patients with 0 or 1 variant (p = 0.001). After adjusting for other factors, each additional rare variant increased the risk of respiratory failure or death by 60% (p = 0.0098). The presence of the rare variant was associated with the risk of ALS (Odds ratio 1.91, 95% confidence interval 1.03-3.61, p = 0.03), and ALS patients had higher rare variant burden than controls (MB, p = 0.004). Our findings support an oligogenic basis with the burden of rare variants affecting the development and survival of ALS.


Assuntos
Esclerose Amiotrófica Lateral/genética , Esclerose Amiotrófica Lateral/mortalidade , Estudos de Associação Genética , Variação Genética/genética , Adulto , Idoso , Esclerose Amiotrófica Lateral/complicações , Esclerose Amiotrófica Lateral/epidemiologia , D-Aminoácido Oxidase/genética , Proteínas de Ligação a DNA/genética , Feminino , Hong Kong/epidemiologia , Humanos , Masculino , Pessoa de Meia-Idade , Polimorfismo de Nucleotídeo Único , Receptores Proteína Tirosina Quinases/genética , Insuficiência Respiratória/epidemiologia , Insuficiência Respiratória/etiologia , Risco , Superóxido Dismutase-1/genética , Sobrevida , Sequenciamento Completo do Genoma
6.
World Neurosurg ; 106: 85-91, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28606579

RESUMO

BACKGROUND: Antiplatelet resumption in patients who developed intracerebral hemorrhage (ICH) while on antiplatelet therapy (antiplatelet-related ICH) represents an important medical dilemma. We aimed to study the long-term cardiovascular outcomes of antiplatelet-related ICH survivors, and the risk of recurrent ICH with antiplatelet resumption. METHODS: This was an observational study of 109 antiplatelet-related ICH survivors. The clinical end points were recurrent ICH, ischemic vascular events, and vascular death (fatal ICH or ischemic vascular events). Predictors of recurrent ICH and vascular death were derived using a multivariable Cox regression model. RESULTS: The median duration of follow-up was 3.5 years (interquartile range, 1.6-5.8 years). Ischemic vascular events were more common than recurrent ICHs (6.8 per 100 patient-years vs. 2.6 per 100 patient-years; P = 0.028). Antiplatelet use was not associated with an elevated risk of recurrent ICH (hazard ratio [HR], 1.11, 95% confidence interval [CI], 0.27-4.62). A mean follow-up systolic blood pressure of >140 mmHg increased the risk of both recurrent ICH (HR, 4.28; 95% CI, 1.01-18.11) and vascular death (HR, 11.14; 95% CI, 2.72-45.62). Cerebral amyloid angiopathy (CAA) was an independent predictor for recurrent ICH (HR, 24.34; 95% CI, 2.80-211.47). CONCLUSIONS: Antiplatelet resumption after antiplatelet-related ICH did not appear to carry a clinically significant risk of recurrent ICH, whereas inadequate blood pressure control and CAA contributed to a more robust risk. Antiplatelet resumption should be considered, especially in survivors with adequate blood pressure control and without CAA.


Assuntos
Hemorragia Cerebral/induzido quimicamente , Inibidores da Agregação de Plaquetas/efeitos adversos , Idoso , Hemorragia Cerebral/mortalidade , Substituição de Medicamentos , Feminino , Humanos , Isquemia/etiologia , Isquemia/mortalidade , Masculino , Recidiva , Estudos Retrospectivos , Fatores de Risco , Sobreviventes
7.
Neurology ; 88(24): 2260-2267, 2017 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-28515266

RESUMO

OBJECTIVE: In patients with TIA and ischemic stroke, we validated the total small vessel disease (SVD) score by determining its prognostic value for recurrent stroke. METHODS: Two independent prospective studies were conducted, one comprising predominantly Caucasian patients with TIA/ischemic stroke (Oxford Vascular Study [OXVASC]) and one predominantly Chinese patients with ischemic stroke (University of Hong Kong [HKU]). Cerebral MRI was performed and assessed for lacunes, microbleeds, white matter hyperintensities (WMH), and perivascular spaces (PVS). Predictive value of total SVD score for risk of recurrent stroke was determined and potential refinements considered. RESULTS: In 2,002 patients with TIA/ischemic stroke (OXVASC n = 1,028, HKU n = 974, 6,924 patient-years follow-up), a higher score was associated with an increased risk of recurrent ischemic stroke (adjusted hazard ratio [HR] per unit increase: 1.32, 1.16-1.51, p < 0.0001; c statistic 0.61, 0.56-0.65, p < 0.0001) and intracerebral hemorrhage (ICH) (HR 1.54, 1.11-2.13, p = 0.009; c statistic 0.65, 0.54-0.76, p = 0.006). A higher score predicted recurrent stroke in SVD and non-SVD TIA/ischemic stroke subtypes (c statistic 0.67, 0.59-0.74, p < 0.0001 and 0.60, 0.55-0.65, p < 0.0001). Including burden of microbleeds and WMH and adjusting the cutoff of basal ganglia PVS potentially improved predictive power for ICH (c statistic 0.71, 0.60-0.81, phet = 0.45), but not for recurrent ischemic stroke (c statistic 0.60, 0.56-0.65, phet = 0.76) on internal validation. CONCLUSIONS: The total SVD score has predictive value for recurrent stroke after TIA/ischemic stroke. Prediction of recurrence in patients with nonlacunar events highlights the potential role of SVD in wider stroke etiology.


Assuntos
Isquemia Encefálica/diagnóstico , Doenças de Pequenos Vasos Cerebrais/diagnóstico , Risco , Acidente Vascular Cerebral/diagnóstico , Idoso , Grupo com Ancestrais do Continente Asiático , Isquemia Encefálica/complicações , Doenças de Pequenos Vasos Cerebrais/complicações , Efeitos Psicossociais da Doença , Grupo com Ancestrais do Continente Europeu , Feminino , Seguimentos , Hong Kong , Humanos , Hemorragias Intracranianas/complicações , Hemorragias Intracranianas/diagnóstico , Masculino , Prognóstico , Modelos de Riscos Proporcionais , Estudos Prospectivos , Recidiva , Acidente Vascular Cerebral/complicações , Reino Unido
8.
Sci Rep ; 7: 40887, 2017 01 18.
Artigo em Inglês | MEDLINE | ID: mdl-28098219

RESUMO

Aging, genetics and environmental toxicity are important etiological factors in Parkinson's disease (PD). However, its pathogenesis remains unclear. A major obstacle is the lack of an appropriate experimental model which incorporates genetic susceptibility, aging and prolonged environmental toxicity. Here, we explored the interplay amongst these factors using mutant LRRK2R1441G (leucine-rich-repeat-kinase-2) knockin mice. We found that mutant primary cortical and mesencephalic dopaminergic neurons were more susceptible to rotenone-induced ATP deficiency and cell death. Compared with wild-type controls, striatal synaptosomes isolated from young mutant mice exhibited significantly lower dopamine uptake after rotenone toxicity, due to reduced striatal synaptosomal mitochondria and synaptic vesicular proton pump protein (V-ATPase H) levels. Mutant mice developed greater locomotor deficits in open-field tests than wild-type mice following low oral rotenone doses given twice weekly over 50 weeks (half their lifespan). The increased locomotor deficit was associated with specific reduction in striatal mitochondrial Complex-I (NDUFS4) in rotenone-treated mutant but not in similarly treated wild-type mice. Our unique experimental model which incorporates genetic effect, natural aging and prolonged oral environmental toxicity administered to mutant knockin LRRK2 mice over half their life span, with observable and measurable phenotype, is invaluable in further studies of the pathogenic process and therapeutics of PD.


Assuntos
Apoptose/efeitos dos fármacos , Serina-Treonina Proteína Quinase-2 com Repetições Ricas em Leucina/genética , Doença de Parkinson/patologia , Rotenona/farmacologia , Administração Oral , Envelhecimento , Animais , Modelos Animais de Doenças , Dopamina/metabolismo , Neurônios Dopaminérgicos/efeitos dos fármacos , Neurônios Dopaminérgicos/metabolismo , Complexo I de Transporte de Elétrons/metabolismo , Técnicas de Introdução de Genes , Serina-Treonina Proteína Quinase-2 com Repetições Ricas em Leucina/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Mutagênese Sítio-Dirigida , Neurônios/citologia , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Doença de Parkinson/tratamento farmacológico , Doença de Parkinson/metabolismo , Rotenona/uso terapêutico , Sinaptossomos/metabolismo , ATPases Vacuolares Próton-Translocadoras/metabolismo
9.
Biochem J ; 473(17): 2671-85, 2016 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-27474410

RESUMO

Autosomal dominant mutations that activate the leucine-rich repeat kinase 2 (LRRK2) cause inherited Parkinson's disease. Recent work has revealed that LRRK2 directly phosphorylates a conserved threonine/serine residue in the effector-binding switch-II motif of a number of Rab GTPase proteins, including Rab10. Here we describe a facile and robust method to assess phosphorylation of endogenous Rab10 in mouse embryonic fibroblasts (MEFs), lung and spleen-derived B-cells, based on the ability of the Phos-tag reagent to retard the electrophoretic mobility of LRRK2-phosphorylated Rab10. We exploit this assay to show that phosphorylation of Rab10 is ablated in kinase-inactive LRRK2[D2017A] knockin MEFs and mouse lung, demonstrating that LRRK2 is the major Rab10 kinase in these cells/tissue. We also establish that the Phos-tag assay can be deployed to monitor the impact that activating LRRK2 pathogenic (G2019S and R1441G) knockin mutations have on stimulating Rab10 phosphorylation. We show that upon addition of LRRK2 inhibitors, Rab10 is dephosphorylated within 1-2 min, markedly more rapidly than the Ser(935) and Ser(1292) biomarker sites that require 40-80 min. Furthermore, we find that phosphorylation of Rab10 is suppressed in LRRK2[S910A+S935A] knockin MEFs indicating that phosphorylation of Ser(910) and Ser(935) and potentially 14-3-3 binding play a role in facilitating the phosphorylation of Rab10 by LRRK2 in vivo The Rab Phos-tag assay has the potential to significantly aid with evaluating the effect that inhibitors, mutations and other factors have on the LRRK2 signalling pathway.


Assuntos
Serina-Treonina Proteína Quinase-2 com Repetições Ricas em Leucina/metabolismo , Inibidores de Proteínas Quinases/farmacologia , Proteínas Quinases/metabolismo , Proteínas rab de Ligação ao GTP/metabolismo , Animais , Camundongos , Camundongos Knockout , Fosforilação , Proteínas rab de Ligação ao GTP/genética
10.
Environ Pollut ; 215: 103-112, 2016 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-27179329

RESUMO

Marine Protected Areas (MPAs) in Hong Kong are situated in close proximity to urbanized areas, and inevitably influenced by wastewater discharges and antifouling biocides leached from vessels. Hence, marine organisms inhabiting these MPAs are probably at risk. Here an integrative approach was employed to comprehensively assess ecological risks of eight priority endocrine disrupting chemicals (EDCs) in four MPAs of Hong Kong. We quantified their concentrations in environmental and biota samples collected in different seasons during 2013-2014, while mussels (Septifer virgatus) and semi-permeable membrane devices were deployed to determine the extent of accumulation of the EDCs. Extracts from the environmental samples were subjected to the yeast estrogen screen and a novel human cell-based catechol-O-methyltransferase ELISA to evaluate their estrogenic activities. The results indicated ecological risks of EDCs in the Cape d'Aguilar Marine Reserve. This integrated approach can effectively evaluate ecological risks of EDCs through linking their concentrations to biological effects.


Assuntos
Disruptores Endócrinos/análise , Disruptores Endócrinos/farmacologia , Estrogênios/farmacologia , Poluentes da Água/análise , Animais , Bivalves/química , Catecol O-Metiltransferase/biossíntese , Cultura em Câmaras de Difusão , Ensaio de Imunoadsorção Enzimática , Sedimentos Geológicos/química , Hong Kong , Humanos , Células MCF-7/efeitos dos fármacos , Medição de Risco , Água do Mar/química , Leveduras/efeitos dos fármacos
11.
Int J Cardiol ; 203: 964-71, 2016 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-26625322

RESUMO

BACKGROUND: Friedreich's ataxia (FRDA), a recessive neurodegenerative disorder commonly associated with hypertrophic cardiomyopathy, is caused by silencing of the frataxin (FXN) gene encoding the mitochondrial protein involved in iron-sulfur cluster biosynthesis. METHODS: Application of our previously established FRDA human induced pluripotent stem cell (hiPSC) derived cardiomyocytes model as a platform to assess the efficacy of treatment with either the antioxidant coenzyme Q10 analog, idebenone (IDE) or the iron chelator, deferiprone (DFP), which are both under clinical trial. RESULTS: DFP was able to more significantly suppress synthesis of reactive oxygen species (ROS) than IDE at the dosages of 25 µM and 10nM respectively which agreed with the reduced rate of intracellular accumulation of iron by DFP treatment from 25 to 50 µM. With regard to cardiac electrical-contraction (EC) coupling function, decay velocity of calcium handling kinetics in FRDA-hiPSC-cardiomyocytes was significantly improved by DFP treatment but not by IDE. Further mechanistic studies revealed that DFP also modulated iron induced mitochondrial stress as reflected by mitochondria network disorganization and decline level of respiratory chain protein, succinate dehydrogenase (CxII) and cytochrome c oxidase (COXIV). In addition, iron-response protein (IRP-1) regulatory loop was overridden by DFP as reflected by resumed level of ferritin (FTH) back to basal level and the attenuated transferrin receptor (TSFR) mRNA level suppression thereby reducing further iron uptake. CONCLUSIONS: DFP modulated iron homeostasis in FRDA-hiPSC-cardiomyocytes and effectively relieved stress-stimulation related to cardiomyopathy. The resuming of redox condition led to the significantly improved cardiac prime events, cardiac electrical-coupling during contraction.


Assuntos
Avaliação Pré-Clínica de Medicamentos/métodos , Ataxia de Friedreich/terapia , Células-Tronco Pluripotentes Induzidas , Ferro/metabolismo , Miócitos Cardíacos/metabolismo , Piridonas/farmacologia , Ubiquinona/análogos & derivados , Antioxidantes/farmacologia , Deferiprona , Ataxia de Friedreich/genética , Ataxia de Friedreich/metabolismo , Regulação da Expressão Gênica , Homeostase , Humanos , Quelantes de Ferro/farmacologia , Proteínas de Ligação ao Ferro/biossíntese , Proteínas de Ligação ao Ferro/genética , Miócitos Cardíacos/patologia , Estresse Oxidativo , RNA/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Ubiquinona/farmacologia
12.
Neuropsychologia ; 80: 102-114, 2016 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-26529488

RESUMO

Previous studies have suggested that the deteriorated visuomotor control in patients with PD (Parkinson's disease) is due to deficits in various aspects of the sensory-motor processing rather than motor control itself. In the current study, by taking a control-theoretic approach, we systematically examined how PD and antiparkinsonian medication affect visuomotor control and the underlying sensory-motor system. We tested 20 PD patients in both ON and OFF medication states and 20 demographically matched healthy controls with a commonly used manual control task. Specifically, in each 95-s trial, participants were instructed to use a joystick to control a randomly moving target to keep it centered on a computer display. We found that although antiparkinsonian medication improved visuomotor control in PD patients, they still showed significantly decreased control precision (measured by RMS error) and response amplitude (gain) as well as increased response delay (phase lag) compared with healthy controls. Our model-driven analysis revealed that PD impairs the responsiveness and the predicting ability of the sensory-motor system as well as the stability of the neuromuscular system. Taking antiparkinsonian medication improves the responsiveness of the sensory-motor system. More importantly, it improves the ability of the sensory-motor system to make sensory predictions of the current control actions (see Wolpert et al., 1995) to anticipate the input error signals and generate control responses ahead of time up to the level of healthy controls. However, taking antiparkinsonian medication does not improve the stability of the neuromuscular system. These results support the claim that the effect of antiparkinsonian medication on visuomotor control is mainly through improving visual-stimulus-dependent sensory-motor processing. The present study provides the first quantitative examination of the effects of PD and antiparkinsonian medication on the visual-stimulus-dependent sensory-motor and visual-stimulus-independent neuromuscular systems underlying visuomotor control. The findings have practical implications for developing sensitive assessment tools to evaluate the efficacy of different therapies for PD and preliminary screening and training tools for fitness-to-drive in PD patients.


Assuntos
Doença de Parkinson/complicações , Transtornos Psicomotores/etiologia , Sensação/fisiologia , Idoso , Análise de Variância , Antiparkinsonianos/farmacologia , Antiparkinsonianos/uso terapêutico , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Doença de Parkinson/tratamento farmacológico , Estimulação Luminosa , Transtornos Psicomotores/tratamento farmacológico , Tempo de Reação/efeitos dos fármacos , Tempo de Reação/fisiologia , Sensação/efeitos dos fármacos , Estatística como Assunto , Fatores de Tempo
13.
Brain Struct Funct ; 221(1): 287-300, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25287513

RESUMO

Visual hallucinations carry poor prognosis in Parkinson's disease. Here we tested the hypothesis that the hippocampus and visuospatial memory impairment play a central role in the pathology of PD with visual hallucinations. Multimodal magnetic resonance imaging of the brain was carried out in 12 people with PD and visual hallucinations; 15 PD individuals without hallucinations; and 14 healthy controls. Age, gender, cognitive ability, and education level were matched across the three groups. PD patients were taking dopaminergic medication. Hippocampal volume, shape, mean diffusivity (MD), and functional connectivity within the whole brain were examined. Visuospatial memory was compared between groups, and correlations with hippocampal MD, functional connectivity, and the severity of hallucinations were explored. There were no macrostructural differences across groups, but individuals with hallucinations had higher diffusivity in posterior hippocampus than the other two groups. Visuospatial memory was poorer in both PD groups compared to controls, and was correlated with hallucinations. Finally, hippocampal functional connectivity in the visual cortices was lower in those with hallucinations than other groups, and this correlated with visuospatial memory impairment. In contrast, functional connectivity between the hippocampus and default mode network regions and frontal regions was greater in the PD hallucinators compared to other groups. We suggest that hippocampal pathology, which disrupts visuospatial memory, makes a key contribution to visual hallucinations in PD. These findings may pave the way for future studies of imaging biomarkers to measure treatment response in those with PD who are most at risk of poor outcomes.


Assuntos
Encéfalo/patologia , Encéfalo/fisiopatologia , Alucinações/etiologia , Alucinações/patologia , Alucinações/fisiopatologia , Hipocampo/patologia , Hipocampo/fisiopatologia , Doença de Parkinson/complicações , Idoso , Mapeamento Encefálico , Feminino , Humanos , Imagem por Ressonância Magnética , Masculino , Memória/fisiologia , Pessoa de Meia-Idade , Imagem Multimodal , Vias Neurais/patologia , Vias Neurais/fisiopatologia , Testes Neuropsicológicos , Memória Espacial/fisiologia
14.
Brain Behav ; 5(4): e00321, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25798335

RESUMO

BACKGROUND: Familial spastic paraplegia (FSP) is a heterogeneous group of disorders characterized primarily by progressive lower limb spasticity and weakness. More than 50 disease loci have been described with different modes of inheritance. Recently, we described a novel missense mutation (c.803G>A, p.R268Q) in the plasma membrane calcium ATPase (PMCA4, or ATP2B4) gene in a Chinese family with autosomal dominant FSP. Further to this finding, here we describe the functional effect of this mutation. METHODS: As PMCA4 removes cytosolic calcium, we measured transient changes and the time-dependent decay of cytosolic calcium level as visualized by using fura-2 fluorescent dye with confocal microscopy in human SH-SY5Y neuroblastoma cells overexpressing either wild-type or R268Q mutant PMCA4. RESULTS: Overexpressing both wild-type and R268Q PMCA4 significantly reduced maximum calcium surge after KCl-induced depolarization as compared with vector control cells. However, cells overexpressing mutant PMCA4 protein demonstrated significantly higher level of calcium surge when compared with wild-type. Furthermore, the steady-state cytosolic calcium concentration in these mutant cells remained markedly higher than the wild-type after SERCA inhibition by thapsigargin. CONCLUSION: Our result showed that p.R268Q mutation in PMCA4 resulted in functional changes in calcium homeostasis in human neuronal cells. This suggests that calcium dysregulation may be associated with the pathogenesis of FSP.


Assuntos
Grupo com Ancestrais do Continente Asiático/genética , Mutação de Sentido Incorreto , Paraplegia Espástica Hereditária/genética , Western Blotting , Cálcio/análise , Corantes Fluorescentes , Fura-2 , Humanos , Microscopia Confocal/métodos , ATPases Transportadoras de Cálcio da Membrana Plasmática , Reação em Cadeia da Polimerase em Tempo Real
15.
Hum Mutat ; 36(5): 496-503, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-25676918

RESUMO

With the rapid advances in high-throughput sequencing technologies, exome sequencing and targeted region sequencing have become routine approaches for identifying mutations of inherited disorders in both genetics research and molecular diagnosis. There is an imminent need for comprehensive and easy-to-use downstream analysis tools to isolate causal mutations in exome sequencing studies. We have developed a user-friendly online framework, wKGGSeq, to provide systematic annotation, filtration, prioritization, and visualization functions for characterizing causal mutation(s) in exome sequencing studies of inherited disorders. wKGGSeq provides: (1) a novel strategy-based procedure for downstream analysis of a large amount of exome sequencing data and (2) a disease-targeted analysis procedure to facilitate clinical diagnosis of well-studied genetic diseases. In addition, it is also equipped with abundant online annotation functions for sequence variants. We demonstrate that wKGGSeq either outperforms or is comparable to two popular tools in several real exome sequencing samples. This tool will greatly facilitate the downstream analysis of exome sequencing data and can play a useful role for researchers and clinicians in identifying causal mutations of inherited disorders. The wKGGSeq is freely available at http://statgenpro.psychiatry.hku.hk/wkggseq or http://jjwanglab.org/wkggseq, and will be updated frequently.


Assuntos
Biologia Computacional/métodos , Internet , Software , Bases de Dados Genéticas , Exoma , Estudos de Associação Genética/métodos , Doenças Genéticas Inatas/diagnóstico , Doenças Genéticas Inatas/genética , Genômica , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Anotação de Sequência Molecular , Navegador
16.
Parkinsonism Relat Disord ; 21(2): 131-7, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25511330

RESUMO

BACKGROUND: Visual hallucinations are an important non-motor complication of Parkinson's disease (PD) and carry a negative prognosis. Their biological basis is uncertain, but may relate to the activity of resting state networks in brain. We therefore aimed to investigate functional activity of brain in patients with visual hallucinations (PDVH) in resting state compared to patients without hallucinations (PDnonVH) and a healthy control group (HC). METHODS: Resting state functional MRI was acquired and the primary analysis compared the amplitude of low-frequency fluctuations (ALFF) across groups. This informed a secondary analysis, in the PD groups only, comparing functional connectivity between a 'seed' region in the occipital lobe and the rest of the brain. RESULTS: Individuals with PDVH showed lower ALFF in bilateral lingual gyrus and cuneus and greater ALFF in temporo-parietal regions, medial temporal gyrus and cerebellum than PDnonVH and HC. PDnonVH also had lower ALFF in occipitoparietal region and greater ALFF in medial temporal gyrus, temporo-parietal and cerebellum regions than HC. Functional connectivity analysis revealed that, although both PD groups had lower occipital functional connectivity relative to the HC group, occipital - corticostriatal connectivity was significantly higher in those with PDVH compared with PDnonVH. CONCLUSION: Our study reveals widespread hemodynamic alterations in PD. However, within a functionally abnormal occipital lobe, those with PDVH have even lower ALFF than non-hallucinators, but have higher occipital functional connectivity with cortical-striatal regions. These findings suggest disruption of pathways underpinning both primary visual perceptual and intrinsic visual integration may contribute to visual hallucinations in PD.


Assuntos
Corpo Estriado/metabolismo , Alucinações/metabolismo , Doença de Parkinson/metabolismo , Descanso , Córtex Visual/metabolismo , Vias Visuais/metabolismo , Idoso , Córtex Cerebral/metabolismo , Feminino , Alucinações/diagnóstico , Humanos , Imagem por Ressonância Magnética/métodos , Masculino , Pessoa de Meia-Idade , Vias Neurais/metabolismo , Doença de Parkinson/diagnóstico , Descanso/fisiologia
17.
Am J Hypertens ; 28(4): 501-7, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25352231

RESUMO

BACKGROUND AND PURPOSE: The Mediterranean-style diet is widely advocated for the prevention of cardiovascular diseases (CVD). Meanwhile, blood pressure variability (BPV) is a novel risk factor for CVD. It is unknown whether dietary pattern plays a role in modulating BPV. METHODS: We prospectively followed-up 274 consecutive patients with stable coronary artery disease (CAD). The Mediterranean diet score (MDS) was derived for all individuals upon recruitment, blood pressure (BP) was measured during each subsequent clinic visit and the visit-to-visit BPV was calculated. The occurrence of major adverse cardiovascular events (MACEs) and all-cause mortality was monitored. RESULTS: After a mean follow-up of 77±12 months, 16.1% of the study population developed MACEs. About 11.3% died from all causes. Patients who developed MACEs or all-cause mortality had a greater systolic BPV compared to those who did not develop an adverse event. Patients who developed a MACE had a lower MDS and further analysis revealed those who developed a stroke had a lower MDS compared with those who did not develop a stroke, but there were no significant differences in MDS between CAD patients with or without subsequent acute coronary syndrome, cardiovascular, or all-cause mortality. After adjusting for confounding variables, a high MDS was an independent predictor for low systolic BPV (B -0.74, 95% confidence interval -1.27 to -0.21, P < 0.01) and was noted to be protective against subsequent development of stroke (hazards ratio 0.48, 95% confidence interval 0.24 to 0.94, P = 0.03). CONCLUSIONS: Among patients with CAD, a higher MDS is associated with a lower visit-to-visit BPV and with lower stroke risk.


Assuntos
Pressão Sanguínea , Doença da Artéria Coronariana/dietoterapia , Dieta Mediterrânea , Hipertensão/dietoterapia , Acidente Vascular Cerebral/prevenção & controle , Idoso , Doença da Artéria Coronariana/diagnóstico , Doença da Artéria Coronariana/mortalidade , Doença da Artéria Coronariana/fisiopatologia , Feminino , Seguimentos , Hong Kong/epidemiologia , Humanos , Hipertensão/diagnóstico , Hipertensão/mortalidade , Hipertensão/fisiopatologia , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Fatores de Proteção , Fatores de Risco , Acidente Vascular Cerebral/diagnóstico , Acidente Vascular Cerebral/mortalidade , Fatores de Tempo , Resultado do Tratamento
18.
Ann Clin Transl Neurol ; 1(3): 199-208, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25356398

RESUMO

OBJECTIVE: Mutations in leucine-rich repeat kinase 2 (LRRK2) pose a significant genetic risk in familial and sporadic Parkinson's disease (PD). R1441 mutation (R1441G/C) in its GTPase domain is found in familial PD. How LRRK2 interacts with synaptic proteins, and its role in dopamine (DA) homeostasis and synaptic vesicle recycling remain unclear. METHODS: To explore the pathogenic effects of LRRK2(R1441G) mutation on nigrostriatal synaptic nerve terminals and locomotor activity, we generated C57BL/6N mice with homozygous LRRK2(R1441G) knockin (KI) mutation, and examined for early changes in nigrostriatal region, striatal synaptosomal [(3)H]-DA uptake and locomotor activity after reserpine-induced DA depletion. RESULTS: Under normal conditions, mutant mice showed no differences, (1) in amount and morphology of nigrostriatal DA neurons and neurites, (2) tyrosine hydroxylase (TH), DA uptake transporter (DAT), vesicular monoamine transporter-2 (VMAT2) expression in striatum, (3) COX IV, LC3B, Beclin-1 expression in midbrain, (4) LRRK2 expression in total cell lysate from whole brain, (5) α-synuclein, ubiquitin, and tau protein immunostaining in midbrain, (6) locomotor activity, compared to wild-type controls. However, after a single intraperitoneal reserpine dose, striatal synaptosomes from young 3-month-old mutant mice demonstrated significantly lower DA uptake with impaired locomotor activity and significantly slower recovery from the effects of reserpine. INTERPRETATION: Although no abnormal phenotype was observed in mutant LRRK2(R1441G) mice, the KI mutation increases vulnerability to reserpine-induced striatal DA depletion and perturbed DA homeostasis resulting in presynaptic dysfunction and locomotor deficits with impaired recovery from reserpine. This subtle nigrostriatal synaptic vulnerability may reflect one of the earliest pathogenic processes in LRRK2-associated PD.

19.
PLoS One ; 9(8): e104790, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25119969

RESUMO

Familial spastic paraplegia (FSP) is a heterogeneous group of disorders characterized primarily by progressive lower limb spasticity and weakness. More than 50 disease loci have been described with different modes of inheritance. In this study, we identified a novel missense mutation (c.803G>A, p.R268Q) in the plasma membrane calcium ATPase (PMCA4, or ATP2B4) gene in a Chinese family with autosomal dominant FSP using whole-exome sequencing and confirmed with Sanger sequencing. This mutation co-segregated with the phenotype in the six family members studied and is predicted to be pathogenic when multiple deleteriousness predictions were combined. This novel R268Q mutation was not present in over 7,000 subjects in public databases, and over 1,000 Han Chinese in our database. Prediction of potential functional consequence of R268Q mutation on PMCA4 by computational modeling revealed that this mutation is located in protein aggregation-prone segment susceptible to protein misfolding. Analysis for thermodynamic protein stability indicated that this mutation destabilizes the PMCA4 protein structure with higher folding free energy. As PMCA4 functions to maintain neuronal calcium homeostasis, our result showed that calcium dysregulation may be associated with the pathogenesis of FSP.


Assuntos
Grupo com Ancestrais do Continente Asiático/genética , Fenótipo , ATPases Transportadoras de Cálcio da Membrana Plasmática/genética , Paraplegia Espástica Hereditária/genética , Sequência de Bases , Exoma/genética , Genes Dominantes/genética , Humanos , Modelos Genéticos , Dados de Sequência Molecular , Mutação de Sentido Incorreto/genética , Linhagem , Dobramento de Proteína , Análise de Sequência de DNA
20.
Hum Brain Mapp ; 35(11): 5658-66, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-24985056

RESUMO

BACKGROUND: Visual hallucinations (VH) are one of the most striking nonmotor symptoms in Parkinson's disease (PD), and predict dementia and mortality. Aberrant default mode network (DMN) is associated with other psychoses. Here, we tested the hypothesis that DMN dysfunction contributes to VH in PD. METHODS: Resting state functional data was acquired from individuals with PD with VH (PDVH) and without VH (PDnonVH), matched for levodopa drug equivalent dose, and a healthy control group (HC). Independent component analysis was used to investigate group differences in functional connectivity within the DMN. In addition, we investigated whether the functional changes associated with hallucinations were accompanied by differences in cortical thickness. RESULTS: There were no group differences in cortical thickness but functional coactivation within components of the DMN was significantly lower in both PDVH and PDnonVH groups compared to HC. Functional coactivation within the DMN was found to be greater in PDVH group relative to PDnonVH group. CONCLUSION: Our study demonstrates, for the first time that, within a functionally abnormal DMN in PD, relatively higher "connectivity" is associated with VH. We postulate that aberrant connectivity in a large scale network affects sensory information processing and perception, and contributes to "positive" symptom generation in PD.


Assuntos
Encéfalo/patologia , Alucinações/complicações , Alucinações/patologia , Doença de Parkinson/complicações , Doença de Parkinson/patologia , Idoso , Encéfalo/irrigação sanguínea , Feminino , Humanos , Processamento de Imagem Assistida por Computador , Imagem por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Oxigênio/sangue , Análise de Regressão
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