RESUMEN
To facilitate clinical trials of disease-modifying therapies for Alzheimer's disease, which are expected to be most efficacious at the earliest and mildest stages of the disease, supportive biomarker information is necessary. The only validated methods for identifying amyloid-ß deposition in the brain-the earliest pathological signature of Alzheimer's disease-are amyloid-ß positron-emission tomography (PET) imaging or measurement of amyloid-ß in cerebrospinal fluid. Therefore, a minimally invasive, cost-effective blood-based biomarker is desirable. Despite much effort, to our knowledge, no study has validated the clinical utility of blood-based amyloid-ß markers. Here we demonstrate the measurement of high-performance plasma amyloid-ß biomarkers by immunoprecipitation coupled with mass spectrometry. The ability of amyloid-ß precursor protein (APP)669-711/amyloid-ß (Aß)1-42 and Aß1-40/Aß1-42 ratios, and their composites, to predict individual brain amyloid-ß-positive or -negative status was determined by amyloid-ß-PET imaging and tested using two independent data sets: a discovery data set (Japan, n = 121) and a validation data set (Australia, n = 252 including 111 individuals diagnosed using 11C-labelled Pittsburgh compound-B (PIB)-PET and 141 using other ligands). Both data sets included cognitively normal individuals, individuals with mild cognitive impairment and individuals with Alzheimer's disease. All test biomarkers showed high performance when predicting brain amyloid-ß burden. In particular, the composite biomarker showed very high areas under the receiver operating characteristic curves (AUCs) in both data sets (discovery, 96.7%, n = 121 and validation, 94.1%, n = 111) with an accuracy approximately equal to 90% when using PIB-PET as a standard of truth. Furthermore, test biomarkers were correlated with amyloid-ß-PET burden and levels of Aß1-42 in cerebrospinal fluid. These results demonstrate the potential clinical utility of plasma biomarkers in predicting brain amyloid-ß burden at an individual level. These plasma biomarkers also have cost-benefit and scalability advantages over current techniques, potentially enabling broader clinical access and efficient population screening.
Asunto(s)
Enfermedad de Alzheimer/sangre , Enfermedad de Alzheimer/diagnóstico , Péptidos beta-Amiloides/sangre , Precursor de Proteína beta-Amiloide/sangre , Fragmentos de Péptidos/sangre , Anciano , Enfermedad de Alzheimer/líquido cefalorraquídeo , Enfermedad de Alzheimer/metabolismo , Péptidos beta-Amiloides/líquido cefalorraquídeo , Péptidos beta-Amiloides/metabolismo , Precursor de Proteína beta-Amiloide/metabolismo , Australia , Biomarcadores/sangre , Biomarcadores/líquido cefalorraquídeo , Biomarcadores/metabolismo , Encéfalo/metabolismo , Estudios de Casos y Controles , Disfunción Cognitiva/sangre , Disfunción Cognitiva/metabolismo , Análisis Costo-Beneficio , Femenino , Humanos , Inmunoprecipitación , Japón , Masculino , Espectrometría de Masas , Fragmentos de Péptidos/líquido cefalorraquídeo , Fragmentos de Péptidos/metabolismo , Tomografía de Emisión de Positrones , Reproducibilidad de los ResultadosRESUMEN
OBJECTIVE: People with neuropsychiatric symptoms often experience delay in accurate diagnosis. Although cerebrospinal fluid neurofilament light (CSF NfL) shows promise in distinguishing neurodegenerative disorders (ND) from psychiatric disorders (PSY), its accuracy in a diagnostically challenging cohort longitudinally is unknown. METHODS: We collected longitudinal diagnostic information (mean = 36 months) from patients assessed at a neuropsychiatry service, categorising diagnoses as ND/mild cognitive impairment/other neurological disorders (ND/MCI/other) and PSY. We pre-specified NfL > 582 pg/mL as indicative of ND/MCI/other. RESULTS: Diagnostic category changed from initial to final diagnosis for 23% (49/212) of patients. NfL predicted the final diagnostic category for 92% (22/24) of these and predicted final diagnostic category overall (ND/MCI/other vs. PSY) in 88% (187/212), compared to 77% (163/212) with clinical assessment alone. CONCLUSIONS: CSF NfL improved diagnostic accuracy, with potential to have led to earlier, accurate diagnosis in a real-world setting using a pre-specified cut-off, adding weight to translation of NfL into clinical practice.
Asunto(s)
Enfermedad de Alzheimer , Disfunción Cognitiva , Enfermedades Neurodegenerativas , Humanos , Enfermedad de Alzheimer/diagnóstico , Proteínas de Neurofilamentos/líquido cefalorraquídeo , Filamentos Intermedios , Enfermedades Neurodegenerativas/diagnóstico , Enfermedades Neurodegenerativas/líquido cefalorraquídeo , Disfunción Cognitiva/diagnóstico , Biomarcadores/líquido cefalorraquídeoRESUMEN
The two hallmarks of Alzheimer's disease (AD) are amyloid-ß (Aß) plaques and neurofibrillary tangles marked by phosphorylated tau. Increasing evidence suggests that aggregating Aß drives tau accumulation, a process that involves synaptic degeneration leading to cognitive impairment. Conversely, there is a realization that non-fibrillar (oligomeric) forms of Aß mediate toxicity in AD. Fibrillar (filamentous) aggregates of proteins across the spectrum of the primary and secondary tauopathies were the focus of recent structural studies with a filament structure-based nosologic classification, but less emphasis was given to non-filamentous co-aggregates of insoluble proteins in the fractions derived from post-mortem human brains. Here, we revisited sarkosyl-soluble and -insoluble extracts to characterize tau and Aß species by quantitative targeted mass spectrometric proteomics, biochemical assays, and electron microscopy. AD brain sarkosyl-insoluble pellets were greatly enriched with Aß42 at almost equimolar levels to N-terminal truncated microtubule-binding region (MTBR) isoforms of tau with multiple site-specific post-translational modifications (PTMs). MTBR R3 and R4 tau peptides were most abundant in the sarkosyl-insoluble materials with a 10-fold higher concentration than N-terminal tau peptides. This indicates that the major proportion of the enriched tau was the aggregation-prone N-terminal and proline-rich region (PRR) of truncated mixed 4R and 3R tau with more 4R than 3R isoforms. High concentration and occupancies of site-specific phosphorylation pT181 (~22%) and pT217 (~16%) (key biomarkers of AD) along with other PTMs in the PRR and MTBR indicated a regional susceptibility of PTMs in aggregated tau. Immunogold labelling revealed that tau may exist in globular non-filamentous form (N-terminal intact tau) co-localized with Aß in the sarkosyl-insoluble pellets along with tau filaments (N-truncated MTBR tau). Our results suggest a model that Aß and tau interact forming globular aggregates, from which filamentous tau and Aß emerge. These characterizations contribute towards unravelling the sequence of events which lead to end-stage AD changes.
Asunto(s)
Enfermedad de Alzheimer , Humanos , Enfermedad de Alzheimer/metabolismo , Detergentes/química , Detergentes/metabolismo , Proteómica/métodos , Péptidos beta-Amiloides/metabolismo , Encéfalo/metabolismo , Isoformas de Proteínas/metabolismo , Proteínas tau/metabolismoRESUMEN
BACKGROUND AND AIMS: Neurodegeneration underpins the pathological processes of younger-onset dementia (YOD) and has been implicated in primary psychiatric disorders (PSYs). Cerebrospinal fluid (CSF) neurofilament light (NfL) has been used to investigate neurodegeneration severity through correlation with structural brain changes in various conditions, but has seldom been evaluated in YOD and PSYs. METHODS: This retrospective study included patients with YOD or PSYs with magnetic resonance imaging (MRI) of the brain and CSF NfL analysis. Findings from brain MRI were analysed using automated volumetry (volBrain) to measure white matter (WM), grey matter (GM) and whole brain (WB) volumes expressed as percentages of total intracranial volume. Correlations between NfL and brain volume measurements were computed whilst adjusting for age. RESULTS: Seventy patients (47 with YOD and 23 with PSY) were identified. YOD types included Alzheimer disease and behavioural variant frontotemporal dementia. PSY included schizophrenia and major depressive disorder. MRI brain sequences were either fast spoiler gradient-echo (FSPGR) or magnetization-prepared rapid acquisition gradient-echo (MPRAGE). In the total cohort, higher NfL was associated with reduced WB in the FSPGR and MPRAGE sequences (r = -0.402 [95% confidence interval (CI), -0.593 to -0.147], P = 0.008 and r = -0.625 [95% CI, -0.828 to -0.395], P < 0.001, respectively). Higher NfL was related to reduced GM in FSPGR (r = 0.385 [95% CI, -0.649 to -0.014], P = 0.017) and reduced WM in MPRAGE (r = -0.650 [95% CI, -0.777 to -0.307], P < 0.001). Similar relationships were seen in YOD, but not in PSY. CONCLUSION: Higher CSF NfL is related to brain atrophy in YOD, further supporting its use as a nonspecific marker of neurodegeneration severity.
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Enfermedad de Alzheimer , Trastorno Depresivo Mayor , Humanos , Estudios Retrospectivos , Proteínas de Neurofilamentos/líquido cefalorraquídeo , Trastorno Depresivo Mayor/diagnóstico por imagen , Filamentos Intermedios , Enfermedad de Alzheimer/diagnóstico por imagen , Atrofia , BiomarcadoresRESUMEN
INTRODUCTION: Many patients with cognitive and neuropsychiatric symptoms face diagnostic delay and misdiagnosis. We investigated whether cerebrospinal fluid (CSF) neurofilament light (NfL) and total-tau (t-tau) could assist in the clinical scenario of differentiating neurodegenerative (ND) from psychiatric disorders (PSY), and rapidly progressive disorders. METHODS: Biomarkers were examined in patients from specialist services (ND and PSY) and a national Creutzfeldt-Jakob registry (Creutzfeldt-Jakob disease [CJD] and rapidly progressive dementias/atypically rapid variants of common ND, RapidND). RESULTS: A total of 498 participants were included: 197 ND, 67 PSY, 161 CJD, 48 RapidND, and 20 controls. NfL was elevated in ND compared to PSY and controls, with highest levels in CJD and RapidND. NfL distinguished ND from PSY with 95%/78% positive/negative predictive value, 92%/87% sensitivity/specificity, 91% accuracy. NfL outperformed t-tau in most real-life clinical diagnostic dilemma scenarios, except distinguishing CJD from RapidND. DISCUSSION: We demonstrated strong generalizable evidence for the diagnostic utility of CSF NfL in differentiating ND from psychiatric disorders, with high accuracy.
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Enfermedad de Alzheimer , Síndrome de Creutzfeldt-Jakob , Trastornos Mentales , Humanos , Enfermedad de Alzheimer/diagnóstico , Enfermedad de Alzheimer/líquido cefalorraquídeo , Diagnóstico Tardío , Filamentos Intermedios , Proteínas tau/líquido cefalorraquídeo , Síndrome de Creutzfeldt-Jakob/diagnóstico , Síndrome de Creutzfeldt-Jakob/líquido cefalorraquídeo , Biomarcadores/líquido cefalorraquídeoRESUMEN
INTRODUCTION: The current practice of quantifying cerebrospinal fluid (CSF) biomarkers as an aid in the diagnosis of Alzheimer's disease (AD) varies from center to center. For a same biochemical profile, interpretation and reporting of results may differ, which can lead to misunderstandings and raises questions about the commutability of tests. METHODS: We obtained a description of (pre-)analytical protocols and sample reports from 40 centers worldwide. A consensus approach allowed us to propose harmonized comments corresponding to the different CSF biomarker profiles observed in patients. RESULTS: The (pre-)analytical procedures were similar between centers. There was considerable heterogeneity in cutoff definitions and report comments. We therefore identified and selected by consensus the most accurate and informative comments regarding the interpretation of CSF biomarkers in the context of AD diagnosis. DISCUSSION: This is the first time that harmonized reports are proposed across worldwide specialized laboratories involved in the biochemical diagnosis of AD.
Asunto(s)
Enfermedad de Alzheimer , Humanos , Enfermedad de Alzheimer/diagnóstico , Enfermedad de Alzheimer/líquido cefalorraquídeo , Biomarcadores/líquido cefalorraquídeo , Péptidos beta-Amiloides/líquido cefalorraquídeo , Proteínas tau/líquido cefalorraquídeo , Fragmentos de Péptidos/líquido cefalorraquídeoRESUMEN
OBJECTIVE: Neurofilament light has shown promise as a biomarker for diagnosis, staging and prognosis in a wide range of neurological and neurodegenerative disorders. This study explored the utility of cerebrospinal fluid neurofilament light in distinguishing primary psychiatric disorders from neurodegenerative and neurological disorders, a common diagnostic dilemma for psychiatrists and neurologists. METHODS: This cross-sectional retrospective pilot study assessed cerebrospinal fluid neurofilament light on patients referred to a tertiary neuropsychiatry service from 2009 to 2017 for diagnostic assessment of neuropsychiatric and neurocognitive symptoms, where a neurodegenerative disorder was a differential diagnosis, who received lumbar punctures as part of a comprehensive workup. The most recent gold-standard clinical consensus diagnosis was categorised into psychiatric disorder or neurodegenerative or neurological disorder. Data from healthy controls were available for comparison. Data extraction and diagnostic categorisation was blinded to neurofilament light results. RESULTS: A total of 129 participants were included: 77 neurodegenerative or neurological disorder (mean age 57 years, including Alzheimer's dementia, frontotemporal dementia), 31 psychiatric disorder (mean age 51 years, including schizophrenia, major depressive disorder) and 21 healthy controls (mean age 66 years). Neurofilament light was significantly higher in neurodegenerative or neurological disorder (M = 3560 pg/mL, 95% confidence intervals = [2918, 4601]) compared to psychiatric disorder (M = 949 pg/mL, 95% confidence intervals = [830, 1108]) and controls (M = 1036 pg/mL, 95% confidence intervals = [908, 1165]). Neurofilament light distinguished neurodegenerative or neurological disorder from psychiatric disorder with an area under the curve of 0.94 (95% confidence intervals = [0.89, 0.98]); a cut-off of 1332 pg/mL was associated with 87% sensitivity and 90% specificity. CONCLUSION: Cerebrospinal fluid neurofilament light shows promise as a diagnostic test to assist with the often challenging diagnostic dilemma of distinguishing psychiatric disorders from neurodegenerative and neurological disorders. Further studies are warranted to replicate and expand on these findings, including on plasma neurofilament light.
Asunto(s)
Trastornos Mentales/líquido cefalorraquídeo , Trastornos Mentales/diagnóstico , Enfermedades Neurodegenerativas/líquido cefalorraquídeo , Enfermedades Neurodegenerativas/diagnóstico , Proteínas de Neurofilamentos/líquido cefalorraquídeo , Anciano , Enfermedad de Alzheimer/líquido cefalorraquídeo , Enfermedad de Alzheimer/diagnóstico , Biomarcadores/líquido cefalorraquídeo , Estudios Transversales , Trastorno Depresivo Mayor/líquido cefalorraquídeo , Trastorno Depresivo Mayor/diagnóstico , Diagnóstico Diferencial , Femenino , Demencia Frontotemporal/líquido cefalorraquídeo , Demencia Frontotemporal/diagnóstico , Humanos , Masculino , Persona de Mediana Edad , Proyectos Piloto , Esquizofrenia/líquido cefalorraquídeo , Esquizofrenia/diagnósticoRESUMEN
Increasingly, evidence is accumulating pointing at a protective role of a healthy diet at decreasing the risk of Alzheimer's disease. To test the effectiveness of nutritional components, the following food-derived compounds: curcumin alone (curcumin), curcumin combined with (-)epigallocatechin-3-gallate (EGCG), docosahexaenoic acid (DHA) and α-lipoic acid (ALA) (curcuminâ¯+â¯EDA), or a combination of EGCG, DHA and ALA (EDA) were assessed in male Tg2576 transgenic mice on amyloid plaque load, amyloid levels (Aß40/Aß42, but not oligomers due to tissue limitations), microglial activation and memory using the contextual and cued fear conditioning test. The combination diet EDA, resulted in the strongest reduction of amyloid plaque load in both the cortical (pâ¯<â¯.0001) and hippocampal (pâ¯<â¯.0001) areas of the Tg2576 mouse brain, along with lower Aß40/Aß42 levels in the frontal cortex (pâ¯=â¯.000129 and pâ¯=â¯.000039, respectively) and Aß42 levels in the temporal lobe (pâ¯=â¯.000082). A curcumin only diet was shown to lower amyloid plaque load (pâ¯=â¯.028), but when combined with EGCG, DHA and ALA did not result in further decreases in amyloid plaque load. The EDA combination group showed the most prominent decrease in microglial activation (number of microglia around plaques: pâ¯<â¯.05 and pâ¯<â¯.0001, respectively, for the cortex and hippocampus). Analysing the hippocampal associated contextual fear conditioning revealed that both the curcumin+EDA (pâ¯<â¯.0001) and EDA groups (pâ¯=â¯.001) spent increased time on freezing compared to the control group. In addition, the curcumin+EDA group showed a significant increase in time spent freezing compared with the curcumin only group. In the amygdala associated cued test, all mice demonstrated the ability to associate the conditioned stimulus with the unconditioned stimulus as evidenced by a significant increase in freezing behaviour in response to the presentation of the cue (pâ¯<â¯.0001). Post-hoc analysis showed that only curcumin+EDA (pâ¯<â¯.0001) and EDA groups (pâ¯<â¯.0001) developed a significant increase in freezing during the cue presentation. The results from this study show that the combination of EGCG, DHA and ALA (EDA) appeared to have the most potent anti-inflammatory and neuroprotective effect. Our results also demonstrate that interactions between nutraceutical products might result in counterproductive outcomes, highlighting the fact that manufacturers of nutraceuticals containing multiple compounds should be careful not to claim additive or synergistic effects of their combination products in vivo without having tested it in animal models and/or human clinical trials.
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Enfermedad de Alzheimer , Dieta Saludable , Suplementos Dietéticos , Inflamación , Enfermedad de Alzheimer/metabolismo , Enfermedad de Alzheimer/patología , Péptidos beta-Amiloides/metabolismo , Animales , Antioxidantes/administración & dosificación , Curcumina/administración & dosificación , Modelos Animales de Enfermedad , Ácidos Docosahexaenoicos/administración & dosificación , Masculino , Ratones , Ratones Transgénicos , Fármacos Neuroprotectores/administración & dosificación , Placa Amiloide/patología , Ácido Tióctico/administración & dosificaciónRESUMEN
INTRODUCTION: Large longitudinal biomarkers database focusing on middle age is needed for Alzheimer's disease (AD) prevention. METHODS: Data for cerebrospinal fluid analytes, molecular imaging of cerebral fibrillar ß-amyloid with positron emission tomography, magnetic resonance imaging-based brain structures, and clinical/cognitive outcomes were harmonized across eight AD biomarker studies. Statistical power was estimated. RESULTS: The harmonized database included 7779 participants with clinical/cognitive data: 3542 were 18â¼65 years at the baseline, 5865 had longitudinal cognitive data for a median of 4.7 years, 2473 participated in the cerebrospinal fluid studies (906 had longitudinal data), 2496 participated in the magnetic resonance imaging studies (1283 had longitudinal data), and 1498 participated in the positron emission tomography amyloid studies (849 had longitudinal data). The database provides adequate power for detecting early biomarker changes, and demonstrates the feasibility of AD prevention trials on middle-aged individuals. DISCUSSION: The harmonized database is an optimum resource to design AD prevention trials decades before symptomatic onset.
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Biomarcadores/líquido cefalorraquídeo , Cognición/fisiología , Adulto , Enfermedad de Alzheimer/prevención & control , Péptidos beta-Amiloides/líquido cefalorraquídeo , Encéfalo/patología , Bases de Datos Factuales , Femenino , Humanos , Estudios Longitudinales , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Tomografía de Emisión de Positrones , Adulto JovenRESUMEN
We fractionated frontal cortical grey matter from human Alzheimer's disease and control subjects into four biochemically defined pools that represent four distinct compartments: soluble/cytosolic, peripheral membrane/vesicular cargo, integral lipid/membranous pools and aggregated/insoluble debris. Most of the readily extractable amyloid-ß remains associated with a lipid/membranous compartment. There is an exchange of amyloid-ß between the biochemical pools that was lost for the amyloid-ß42 species in Alzheimer's disease, consistent with the peptide being irreversibly trapped in extracellular deposits. The quantitative amyloid-ß data, combined with magnetic resonance imaging volumetric analysis of the amount of cortical grey matter in brain, allowed us to estimate the total mass of amyloid-ß in Alzheimer's disease (6.5 mg) and control (1.7 mg) brains. The threshold positron emission tomography standard uptake value ratio of 1.4 equates to 5.0 µg amyloid-ß/g of grey matter and the mean Alzheimer's disease dementia standard uptake value ratio level of 2.3 equates to 11.20 µg amyloid-ß/g of grey matter. It takes 19 years to accumulate amyloid from the threshold positron emission tomography standard uptake value ratio to the mean value observed for Alzheimer's disease dementia. This accumulation time window combined with the difference of 4.8 mg of amyloid-ß between Alzheimer's disease and control brain allows for a first approximation of amyloid-ß accumulation of 28 ng/h. This equates to an estimated 2-5% of the total amyloid-ß production being deposited as insoluble plaques. Understanding these rates of amyloid-ß accumulation allows for a more quantitative approach in targeting the failure of amyloid-ß clearance in sporadic Alzheimer's disease.
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Enfermedad de Alzheimer/metabolismo , Péptidos beta-Amiloides/metabolismo , Lóbulo Frontal/metabolismo , Sustancia Gris/metabolismo , Placa Amiloide/metabolismo , Enfermedad de Alzheimer/patología , Estudios de Casos y Controles , Lóbulo Frontal/patología , Sustancia Gris/patología , Humanos , Imagen por Resonancia Magnética , Neuroimagen , Tomografía de Emisión de Positrones , Factores de TiempoRESUMEN
The extracellular accumulation of amyloid ß (Aß) peptides is characteristic of Alzheimer's disease (AD). However, formation of diffusible, oligomeric forms of Aß, both on and off pathways to amyloid fibrils, is thought to include neurotoxic species responsible for synaptic loss and neurodegeneration, rather than polymeric amyloid aggregates. The 8-hydroxyquinolines (8-HQ) clioquinol (CQ) and PBT2 were developed for their ability to inhibit metal-mediated generation of reactive oxygen species from Aß:Cu complexes and have both undergone preclinical and Phase II clinical development for the treatment of AD. Their respective modes of action are not fully understood and may include both inhibition of Aß fibrillar polymerization and direct depolymerization of existing Aß fibrils. In the present study, we find that CQ and PBT2 can interact directly with Aß and affect its propensity to aggregate. Using a combination of biophysical techniques, we demonstrate that, in the presence of these 8-HQs and in the absence of metal ions, Aß associates with two 8-HQ molecules and forms a dimer. Furthermore, 8-HQ bind Aß with an affinity of 1-10 µm and suppress the formation of large (>30 kDa) oligomers. The stabilized low molecular weight species are nontoxic. Treatment with 8-HQs also reduces the levels of in vivo soluble oligomers in a Caenorhabditis elegans model of Aß toxicity. We propose that 8-HQs possess an additional mechanism of action that neutralizes neurotoxic Aß oligomer formation through stabilization of small (dimeric) nontoxic Aß conformers.
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Enfermedad de Alzheimer/metabolismo , Péptidos beta-Amiloides/metabolismo , Hidroxiquinolinas/metabolismo , Fragmentos de Péptidos/metabolismo , Péptidos beta-Amiloides/química , Péptidos beta-Amiloides/ultraestructura , Animales , Benzotiazoles , Biofisica , Caenorhabditis elegans , Células Cultivadas , Corteza Cerebral/citología , Cromatografía en Gel , Clioquinol/análogos & derivados , Clioquinol/metabolismo , Ensayo de Inmunoadsorción Enzimática , Humanos , Ratones , Microscopía Electrónica , Neuronas/efectos de los fármacos , Neuronas/metabolismo , Fragmentos de Péptidos/química , Fragmentos de Péptidos/ultraestructura , Unión Proteica/efectos de los fármacos , Dispersión del Ángulo Pequeño , Tiazoles/metabolismoRESUMEN
All cases of Huntington's disease (HD) are caused by mutant huntingtin protein (mhtt), yet the molecular mechanisms that link mhtt to disease symptoms are not fully elucidated. Given glycogen synthase kinase-3 (GSK3) is implicated in several neurodegenerative diseases as a molecular mediator of neuronal decline and widely touted as a therapeutic target, we investigated GSK3 in cells expressing mhtt, brains of R6/1 HD mice and post-mortem human brain samples. Consistency in data across the two models and the human brain samples indicate decreased GSK3 signalling contributes to neuronal dysfunction in HD. Inhibitory phosphorylation of GSK3 (pGSK3) was elevated in mhtt cells and this appeared related to an overall energy metabolism deficit as the mhtt cells had less ATP and inhibiting ATP production in control cells expressing non-pathogenic htt with paraquat also increased pGSK3. pGSK3 was increased and ATP levels decreased in the frontal cortex and striatum of R6/1 mice and levels of cortical pGSK3 inversely correlated with cognitive function of the mice. Consistent with decreased GSK3 activity in the R6/1 mouse brain, ß-catenin levels were increased and phosphorylation of collapsin response mediator protein-2 (CRMP2) decreased in the frontal cortex where inhibitory phosphorylation of GSK3 was the greatest. pGSK3 was predominantly undetectable in HD and healthy control human brain samples, but levels of total GSK3 were decreased in the HD-affected frontal cortex and this correlated with decreased pCRMP2. Thus, disruptions to cortical GSK3 signalling, possibly due to localized energy metabolism deficits, appear to contribute to the cognitive symptoms of HD.
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Corteza Cerebral/metabolismo , Cuerpo Estriado/metabolismo , Glucógeno Sintasa Quinasa 3/genética , Enfermedad de Huntington/genética , Péptidos y Proteínas de Señalización Intercelular/genética , Proteínas del Tejido Nervioso/genética , Adenosina Trifosfato/biosíntesis , Anciano , Anciano de 80 o más Años , Animales , Línea Celular , Corteza Cerebral/patología , Cuerpo Estriado/patología , Modelos Animales de Enfermedad , Femenino , Regulación de la Expresión Génica , Glucógeno Sintasa Quinasa 3/metabolismo , Humanos , Proteína Huntingtina , Enfermedad de Huntington/metabolismo , Enfermedad de Huntington/patología , Péptidos y Proteínas de Señalización Intercelular/metabolismo , Masculino , Ratones , Ratones Transgénicos , Persona de Mediana Edad , Proteínas del Tejido Nervioso/metabolismo , Neuronas/efectos de los fármacos , Neuronas/metabolismo , Neuronas/patología , Paraquat/farmacología , Fosforilación , Transducción de Señal , beta Catenina/genética , beta Catenina/metabolismoRESUMEN
Mutations in the metallo-protein Cu/Zn-superoxide dismutase (SOD1) cause amyotrophic lateral sclerosis (ALS) in humans and an expression level-dependent phenotype in transgenic rodents. We show that oral treatment with the therapeutic agent diacetyl-bis(4-methylthiosemicarbazonato)copper(II) [Cu(II)(atsm)] increased the concentration of mutant SOD1 (SOD1G37R) in ALS model mice, but paradoxically improved locomotor function and survival of the mice. To determine why the mice with increased levels of mutant SOD1 had an improved phenotype, we analyzed tissues by mass spectrometry. These analyses revealed most SOD1 in the spinal cord tissue of the SOD1G37R mice was Cu deficient. Treating with Cu(II)(atsm) decreased the pool of Cu-deficient SOD1 and increased the pool of fully metallated (holo) SOD1. Tracking isotopically enriched (65)Cu(II)(atsm) confirmed the increase in holo-SOD1 involved transfer of Cu from Cu(II)(atsm) to SOD1, suggesting the improved locomotor function and survival of the Cu(II)(atsm)-treated SOD1G37R mice involved, at least in part, the ability of the compound to improve the Cu content of the mutant SOD1. This was supported by improved survival of SOD1G37R mice that expressed the human gene for the Cu uptake protein CTR1. Improving the metal content of mutant SOD1 in vivo with Cu(II)(atsm) did not decrease levels of misfolded SOD1. These outcomes indicate the metal content of SOD1 may be a greater determinant of the toxicity of the protein in mutant SOD1-associated forms of ALS than the mutations themselves. Improving the metal content of SOD1 therefore represents a valid therapeutic strategy for treating ALS caused by SOD1.
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Esclerosis Amiotrófica Lateral , Neuronas Motoras/efectos de los fármacos , Mutación/genética , Compuestos Organometálicos/administración & dosificación , Superóxido Dismutasa/genética , Tiosemicarbazonas/administración & dosificación , Administración Oral , Factores de Edad , Esclerosis Amiotrófica Lateral/tratamiento farmacológico , Esclerosis Amiotrófica Lateral/genética , Esclerosis Amiotrófica Lateral/mortalidad , Esclerosis Amiotrófica Lateral/patología , Animales , Proteínas de Transporte de Catión/genética , Cromatografía en Gel , Complejos de Coordinación , Transportador de Cobre 1 , Modelos Animales de Enfermedad , Humanos , Locomoción/efectos de los fármacos , Locomoción/genética , Ratones , Ratones Transgénicos , Fenotipo , Médula Espinal/efectos de los fármacos , Médula Espinal/metabolismo , Superóxido Dismutasa/metabolismo , Superóxido Dismutasa-1RESUMEN
Amyloid precursor protein (APP) undergoes post-translational modification, including O- and N-glycosylation, ubiquitination, and phosphorylation as it traffics through the secretory pathway. We have previously reported that copper promotes a change in the cellular localization of APP. We now report that copper increases the phosphorylation of endogenous APP at threonine 668 (Thr-668) in SH-SY5Y neuronal cells. The level of APPT668-p (detected using a phospho-site-specific antibody) exhibited a copper-dependent increase. Using confocal microscopy imaging we demonstrate that the phospho-deficient mutant, Thr-668 to alanine (T668A), does not exhibit detectable copper-responsive APP trafficking. In contrast, mutating a serine to an alanine at residue 655 does not affect copper-responsive trafficking. We further investigated the importance of the Thr-668 residue in copper-responsive trafficking by treating SH-SY5Y cells with inhibitors for glycogen synthase kinase 3-ß (GSK3ß) and cyclin-dependent kinases (Cdk), the main kinases that phosphorylate APP at Thr-668 in neurons. Our results show that the GSK3ß kinase inhibitors LiCl, SB 216763, and SB 415286 prevent copper-responsive APP trafficking. In contrast, the Cdk inhibitors Purvalanol A and B had no significant effect on copper-responsive trafficking in SH-SY5Y cells. In cultured primary hippocampal neurons, copper promoted APP re-localization to the axon, and this effect was inhibited by the addition of LiCl, indicating that a lithium-sensitive kinase(s) is involved in copper-responsive trafficking in hippocampal neurons. This is consistent with APP axonal transport to the synapse, where APP is involved in a number of functions. We conclude that copper promotes APP trafficking by promoting a GSK3ß-dependent phosphorylation in SH-SY5Y cells.
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Precursor de Proteína beta-Amiloide/metabolismo , Axones/metabolismo , Cobre/metabolismo , Glucógeno Sintasa Quinasa 3/metabolismo , Hipocampo/metabolismo , Sinapsis/metabolismo , Adyuvantes Inmunológicos/farmacología , Aminofenoles/farmacología , Precursor de Proteína beta-Amiloide/genética , Animales , Línea Celular Tumoral , Glucógeno Sintasa Quinasa 3/antagonistas & inhibidores , Glucógeno Sintasa Quinasa 3/genética , Glucógeno Sintasa Quinasa 3 beta , Hipocampo/citología , Humanos , Indoles/farmacología , Cloruro de Litio/farmacología , Maleimidas/farmacología , Ratones , Mutación Missense , Neuroblastoma/genética , Neuroblastoma/metabolismo , Fosforilación/efectos de los fármacos , Fosforilación/genética , Transporte de Proteínas/efectos de los fármacosRESUMEN
BACKGROUND AND AIM: Genetic variants in the mammalian target of rapamycin (mTOR) gene have become an interesting topic for the study of genetic susceptibility to cancer, but their associations with the risk of gastric cancer have not been fully investigated. MATERIALS AND METHODS: In a hospital-based case-control study of 1002 gastric cancer patients and 1003 cancer-free controls, we genotyped four potentially functional single nucleotide polymorphisms (SNPs) (rs1034528G>C, rs17036508T>C, rs3806317A>G, and rs2295080T>G) of mTOR and assessed their associations with the risk of gastric cancer using univariate and multivariate logistic regression analyses. We also used the multifactorial dimension reduction analysis to explore possible interactions and the false-positive report probabilities to assess significant findings. RESULTS: We found that rs1034528 CG/CC and rs3806317 GA/GG variant genotypes were associated with an increased risk of gastric cancer under a dominant model (adjusted odds ratio=1.27 and 1.22, respectively). In the combined analysis of all four SNPs under investigation, patients with 3-4 risk genotypes of mTOR had a significantly increased risk of gastric cancer (adjusted odds ratio=1.46, 95% confidence interval=1.19-1.79) compared with those with 0-2 risk genotypes. Stratified analysis indicated that this risk was more pronounced in subgroups of men, never-smokers, never-drinkers, and clinical stages III+IV. The multifactorial dimension reduction analysis suggested some evidence of interactions between the combined genotypes and other risk factors for gastric cancer. CONCLUSION: These findings suggest that potentially functional SNPs of mTOR may individually or collectively contribute to the risk of gastric cancer. Larger studies with diverse ethnic populations are warranted to validate our findings.
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Adenocarcinoma/genética , Pueblo Asiatico/genética , Polimorfismo de Nucleótido Simple , Neoplasias Gástricas/genética , Serina-Treonina Quinasas TOR/genética , Estudios de Casos y Controles , Línea Celular , China , Femenino , Expresión Génica , Genes Dominantes , Predisposición Genética a la Enfermedad , Humanos , Masculino , Persona de Mediana Edad , Modelos Genéticos , ARN Mensajero/genética , Factores de RiesgoAsunto(s)
Filamentos Intermedios/química , Trastornos Mentales/líquido cefalorraquídeo , Proteínas de Neurofilamentos/líquido cefalorraquídeo , Enfermedad de Niemann-Pick Tipo C/líquido cefalorraquídeo , Enfermedad de Niemann-Pick Tipo C/terapia , Adulto , Anciano , Biomarcadores/líquido cefalorraquídeo , Estudios de Casos y Controles , Femenino , Humanos , Masculino , Persona de Mediana Edad , Resultado del TratamientoRESUMEN
Tian and Styan have shown many rank equalities for the sum of two and three idempotent matrices and pointed out that rank equalities for the sum P1 + â¯+P k with P1, , P k be idempotent (k > 3) are still open. In this paper, by using block Gaussian elimination, we obtained rank equalities for the sum of finitely many idempotent matrices and then solved the open problem mentioned above. Extensions to scalar-potent matrices and some related matrices are also included.
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Conceptos Matemáticos , Análisis Numérico Asistido por ComputadorRESUMEN
BACKGROUND: A practical biomarker is required to facilitate the preclinical diagnosis of Alzheimer's disease (AD). METHODS: Plasma amyloid beta (Aß)1-40, Aß1-42, Aßn-40, and Aßn-42 peptides were measured at baseline and after 18 months in 771 participants from the Australian Imaging Biomarkers and Lifestyle (AIBL) study of aging. Aß peptide levels were compared with clinical pathology, neuroimaging and neuropsychological measurements. RESULTS: Although inflammatory and renal function covariates influenced plasma Aß levels significantly, a decrease in Aß1-42/Aß1-40 was observed in patients with AD, and was also inversely correlated with neocortical amyloid burden. During the 18 months, plasma Aß1-42 decreased in subjects with mild cognitive impairment (MCI) and in those transitioning from healthy to MCI. CONCLUSION: Our findings are consistent with a number of published plasma Aß studies and, although the prognostic value of individual measures in any given subject is limited, the diagnostic contribution of plasma Aß may demonstrate utility when combined with a panel of peripheral biomarkers.
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Envejecimiento/sangre , Enfermedad de Alzheimer/sangre , Péptidos beta-Amiloides/sangre , Fragmentos de Péptidos/sangre , Anciano , Anciano de 80 o más Años , Enfermedad de Alzheimer/diagnóstico por imagen , Enfermedad de Alzheimer/genética , Apolipoproteína E4/genética , Distribución de Chi-Cuadrado , Disfunción Cognitiva/sangre , Disfunción Cognitiva/diagnóstico por imagen , Estudios de Cohortes , Progresión de la Enfermedad , Femenino , Humanos , Masculino , Persona de Mediana Edad , Pruebas Neuropsicológicas , Tomografía de Emisión de PositronesRESUMEN
We identified a sub-group (25%) of people with schizophrenia (muscarinic receptor deficit schizophrenia (MRDS)) that are characterised because of markedly lower levels of cortical muscarinic M1 receptors (CHRM1) compared to most people with the disorder (non-MRDS). Notably, bioinformatic analyses of our cortical gene expression data shows a disturbance in the homeostasis of a biochemical pathway that regulates levels of CHRM1. A step in this pathway is the processing of ß-amyloid precursor protein (APP) and therefore we postulated there would be altered levels of APP in the frontal cortex from people with MRDS. Here we measure levels of CHRM1 using [3H]pirenzepine binding, soluble APP (sAPP) using Western blotting and amyloid beta peptides (Aß1-40 and Aß1-42) using ELISA in the frontal cortex (Brodmann's area 6: BA 6; MRDS = 14, non-MRDS = 14, controls = 14). We confirmed the MRDS cohort in this study had the expected low levels of [3H]pirenzepine binding. In addition, we showed that people with schizophrenia, independent of their sub-group status, had lower levels of sAPP compared to controls but did not have altered levels of Aß1-40 or Aß1-42. In conclusion, whilst changes in sAPP are not restricted to MRDS our data could indicate a role of APP, which is important in axonal and synaptic pruning, in the molecular pathology of the syndrome of schizophrenia.