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1.
Medicine (Baltimore) ; 99(16): e19620, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32311931

RESUMO

For the diagnosis of mild cognitive impairment (MCI) and Alzheimer disease (AD), variable neuroimaging and neuropsychological tests have been used. We aimed to evaluate the correlation of neuropsychological domain with new amyloid positron emission tomography (PET) study and to validate the availability of new PET tracer.We enrolled 20 patients who underwent C-PiB-PET/CT, new PET tracer F-FC119S PET/CT from November, 2014 to July, 2015. Among them, 10 patients were diagnosed with AD and 10 patients with MCI. The current version of Seoul Neuropsychological Screening Battery (SNSB) II was performed for cognitive evaluation. Each parameter of SNSB was compared between 2 patient groups. Spearman correlation analysis between value of SNSB domain and standardized uptake value ratio (SUVR) of PET was also performed.The AD group presented significant poor z-score in Korean-Boston Naming Test(K-BNT) (P = .01),copy score of Rey Complex Figure Test (RCFT) (P = .049), immediate (P = .028)and delayed memory of Seoul Verbal Learning Test (SVLT) (P = .028), recognition of RCFT (P = .004), "animal" of Controlled Oral Word Association Test (COWAT) (P = .041), color reading of Korean-Color Word Stroop test (K-CWST) (P = .014), and Digit Symbol Coding (DSC) (P = .007) compared with MCI group. That means, except attention domain, all other cognitive domains were relatively impaired in AD compared with MCI. In correlation analysis, we found that poor performances on copy score of RCFT in MCI groups were associated with great beta amyloid burden in frontal area in both C-PiB-PET/CT and F-FC119S PET/CT. In AD group, F-FC119S PET presented more extensive correlation in each cognitive domain with multiple cortical areas compared with C-PiB-PET.The degree of amyloid burden assessed on F-FC119S PET was significantly correlated with neuropsychological test in AD, and also MCI patients. The combination of neuropsychological evaluation with novel F-FC119S PET/CT can be used for valid biomarker for MCI and AD.


Assuntos
Doença de Alzheimer/diagnóstico por imagem , Amiloide/metabolismo , Disfunção Cognitiva/diagnóstico por imagem , Tomografia Computadorizada com Tomografia por Emissão de Pósitrons/métodos , Idoso , Idoso de 80 Anos ou mais , Doença de Alzheimer/metabolismo , Doença de Alzheimer/psicologia , Compostos de Anilina , Radioisótopos de Carbono , Disfunção Cognitiva/metabolismo , Disfunção Cognitiva/psicologia , Feminino , Radioisótopos de Flúor , Humanos , Masculino , Pessoa de Meia-Idade , Neuroimagem/métodos , Testes Neuropsicológicos , Traçadores Radioativos , Tiazóis
2.
Phys Rev Lett ; 124(11): 118102, 2020 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-32242730

RESUMO

The fine interplay between the simultaneous stretching and confinement of amyloid fibrils is probed by combining a microcapillary setup with atomic force microscopy. Single-molecule statistics reveal how the stretching of fibrils changed from force to confinement dominated at different length scales. System order, however, is solely ruled by confinement. Coarse-grained simulations support the results and display the potential to tailor system properties by tuning the two effects. These findings may further help shed light on in vivo amyloid fibril growth and transport in highly confined environments such as blood vessels.


Assuntos
Amiloide/química , Modelos Químicos , Amiloide/metabolismo , Simulação por Computador , Microscopia de Força Atômica/métodos
3.
Nat Med ; 26(3): 398-407, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32161412

RESUMO

Development of tau-based therapies for Alzheimer's disease requires an understanding of the timing of disease-related changes in tau. We quantified the phosphorylation state at multiple sites of the tau protein in cerebrospinal fluid markers across four decades of disease progression in dominantly inherited Alzheimer's disease. We identified a pattern of tau staging where site-specific phosphorylation changes occur at different periods of disease progression and follow distinct trajectories over time. These tau phosphorylation state changes are uniquely associated with structural, metabolic, neurodegenerative and clinical markers of disease, and some (p-tau217 and p-tau181) begin with the initial increases in aggregate amyloid-ß as early as two decades before the development of aggregated tau pathology. Others (p-tau205 and t-tau) increase with atrophy and hypometabolism closer to symptom onset. These findings provide insights into the pathways linking tau, amyloid-ß and neurodegeneration, and may facilitate clinical trials of tau-based treatments.


Assuntos
Doença de Alzheimer/genética , Doença de Alzheimer/metabolismo , Amiloide/metabolismo , Padrões de Herança/genética , Proteínas tau/metabolismo , Adulto , Idoso , Doença de Alzheimer/líquido cefalorraquidiano , Doença de Alzheimer/diagnóstico por imagem , Atrofia , Encéfalo/patologia , Cognição , Progressão da Doença , Feminino , Fluordesoxiglucose F18/química , Humanos , Imagem por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Neuroimagem , Fosforilação , Placa Amiloide/patologia , Solubilidade , Proteínas tau/líquido cefalorraquidiano
4.
Subcell Biochem ; 94: 421-436, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32189310

RESUMO

As normal constituents of blood serum, the Serum Amyloid A (SAA) proteins are small (104 amino acids in humans) and remarkably well-conserved in mammalian evolution. They are synthesized prominently, but not exclusively, in the liver. Fragments of SAA can associate into insoluble fibrils (called "amyloid") characteristic of "secondary" amyloid disease in which they can interrupt normal physiology and lead to organ failure. SAA proteins comprise a family of molecules, two members of which (SAA1 and SAA2) are (along with C-reactive protein, CRP) the most prominent members of the acute phase response (APR) during which their serum levels rise dramatically after trauma, infection and other stimuli. Biologic function (s) of SAA are unresolved but features are consistent with a prominent role in primordial host defense (including the APR ). SAA proteins are lipophilic and contribute to high density lipoproteins (HDL) and cholesterol transport. SAA proteins interact with specific receptors and have been implicated in tissue remodeling through metalloproteinases, local tissue changes in atherosclerosis, cancer metastasis, lung inflammation, maternal-fetal health and intestinal physiology. Molecular details of some of these are emerging.


Assuntos
Proteína Amiloide A Sérica , Reação de Fase Aguda , Amiloide/química , Amiloide/metabolismo , Animais , Colesterol/metabolismo , Doença , Humanos , Lipoproteínas HDL/metabolismo , Fígado/metabolismo , Proteína Amiloide A Sérica/química , Proteína Amiloide A Sérica/metabolismo
5.
Nat Med ; 26(3): 387-397, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32123386

RESUMO

With the potential development of new disease-modifying Alzheimer's disease (AD) therapies, simple, widely available screening tests are needed to identify which individuals, who are experiencing symptoms of cognitive or behavioral decline, should be further evaluated for initiation of treatment. A blood-based test for AD would be a less invasive and less expensive screening tool than the currently approved cerebrospinal fluid or amyloid ß positron emission tomography (PET) diagnostic tests. We examined whether plasma tau phosphorylated at residue 181 (pTau181) could differentiate between clinically diagnosed or autopsy-confirmed AD and frontotemporal lobar degeneration. Plasma pTau181 concentrations were increased by 3.5-fold in AD compared to controls and differentiated AD from both clinically diagnosed (receiver operating characteristic area under the curve of 0.894) and autopsy-confirmed frontotemporal lobar degeneration (area under the curve of 0.878). Plasma pTau181 identified individuals who were amyloid ß-PET-positive regardless of clinical diagnosis and correlated with cortical tau protein deposition measured by 18F-flortaucipir PET. Plasma pTau181 may be useful to screen for tau pathology associated with AD.


Assuntos
Doença de Alzheimer/sangue , Doença de Alzheimer/diagnóstico , Degeneração Lobar Frontotemporal/sangue , Degeneração Lobar Frontotemporal/diagnóstico , Proteínas tau/sangue , Idoso , Doença de Alzheimer/líquido cefalorraquidiano , Amiloide/metabolismo , Peptídeos beta-Amiloides/sangue , Peptídeos beta-Amiloides/líquido cefalorraquidiano , Biomarcadores/sangue , Biomarcadores/líquido cefalorraquidiano , Cognição , Feminino , Degeneração Lobar Frontotemporal/genética , Degeneração Lobar Frontotemporal/patologia , Substância Cinzenta/diagnóstico por imagem , Substância Cinzenta/patologia , Heterozigoto , Humanos , Masculino , Pessoa de Meia-Idade , Mutação/genética , Proteínas de Neurofilamentos/sangue , Fosforilação , Tomografia por Emissão de Pósitrons , Índice de Gravidade de Doença , Proteínas tau/líquido cefalorraquidiano , Proteínas tau/genética
6.
PLoS One ; 15(2): e0229319, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32084222

RESUMO

Biomolecular self-assembly is an emerging bottom-up approach for the synthesis of novel nanomaterials. DNA and viruses have both been used to create scaffolds but the former lacks chemical diversity and the latter lack spatial control. To date, the use of protein scaffolds to template materials on the nanoscale has focused on amyloidogenic proteins that are known to form fibrils or two-protein systems where a second protein acts as a cross-linker. We previously developed a unique approach for self-assembly of nanomaterials based on engineering ß-solenoid proteins (BSPs) to polymerize into micrometer-length fibrils. BSPs have highly regular geometries, tunable lengths, and flat surfaces that are amenable to engineering and functionalization. Here, we present a newly engineered BSP based on the antifreeze protein of the beetle Rhagium inquisitor (RiAFP-m9), which polymerizes into stable fibrils under benign conditions. Gold nanoparticles were used to functionalize the RiAFP-m9 fibrils as well as those assembled from the previously described SBAFP-m1 protein. Cysteines incorporated into the sequences provide site-specific gold attachment. Additionally, silver was deposited on the gold-labelled fibrils by electroless plating to create nanowires. These results bolster prospects for programable self-assembly of BSPs to create scaffolds for functional nanomaterials.


Assuntos
Amiloide/metabolismo , Proteínas Anticongelantes/metabolismo , Ouro/química , Proteínas de Insetos/metabolismo , Nanopartículas Metálicas/química , Nanotecnologia/métodos , Engenharia de Proteínas/métodos , Amiloide/química , Animais , Besouros , Simulação de Dinâmica Molecular
7.
PLoS One ; 15(2): e0229137, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32053667

RESUMO

IMPORTANCE: Clinical guidelines currently recommend against amyloid imaging for cognitively unimpaired persons. The goal of Alzheimer's disease (AD) prevention, together with advances in understanding the pathophysiology of AD, however, has led to trials testing drugs in cognitively unimpaired persons who show evidence of AD biomarkers. Assuming the eventual success of such trials, millions of patients will be affected. There is a need to understand the effects of biomarker disclosure on those individuals. DESIGN: The Study of Knowledge and Reactions to Amyloid Testing (SOKRATES) involved 2 semi-structured telephone interviews with individuals who received amyloid PET scan results as part of screening for research participation. Post-disclosure interviews were conducted at 4 to 12 weeks and again 1 year later. Data were collected from November 5, 2014 to November 30, 2016. Interviews were transcribed and coded in NVivo 12.0. PARTICIPANTS: 80 adults aged 65 and older: 50 who received "elevated" and 30 who received "not-elevated" amyloid PET scan results. MAIN OUTCOMES: Interviews examined four domains: (1) comprehension of the amyloid PET scan result; (2) implications of the result for sense of self, memory, and future; (3) sharing of results with others; and (4) AD risk-reduction behaviors. RESULTS: Participants who received an elevated amyloid PET scan result viewed the result as more serious and sensitive than other medical test results given its unique implications for identity, self-determination, and stigma. In contrast, participants who received a not-elevated amyloid PET scan result described feeling relief and reinterpreted perceived memory impairments as normal aging. Participants with elevated amyloid reported contemplating and making more changes to health behaviors and future plans than their peers with not-elevated amyloid. CONCLUSIONS: Clinical practice in the diagnosis and treatment of persons with preclinical AD, a stage of the disease defined by the presence of biomarkers in the absence of cognitive impairment, will need to address matters of identity, stigma, and life-planning.


Assuntos
Amiloide/metabolismo , Cognição , Revelação , Conhecimentos, Atitudes e Prática em Saúde , Tomografia por Emissão de Pósitrons , Idoso , Idoso de 80 Anos ou mais , Doença de Alzheimer/diagnóstico por imagem , Doença de Alzheimer/prevenção & controle , Feminino , Comportamentos Relacionados com a Saúde , Humanos , Masculino
8.
Photochem Photobiol Sci ; 19(1): 29-33, 2020 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-31932832

RESUMO

We demonstrate amyloid fibril (AF) decomposition induced by NIR-active upconversion nanoparticles complexed with photosensitisers. The process is triggered by upconversion, which initiates a photochemical reaction cascade that culminates in the generation of the highly reactive singlet-oxygen product 1O2 close to the amyloid superstructures, resulting in AF decomposition.


Assuntos
Amiloide/antagonistas & inibidores , Nanopartículas/química , Fármacos Fotossensibilizantes/farmacologia , Amiloide/metabolismo , Humanos , Raios Infravermelhos
9.
Nat Commun ; 11(1): 241, 2020 01 13.
Artigo em Inglês | MEDLINE | ID: mdl-31932609

RESUMO

A major component of bacterial biofilms is curli amyloid fibrils secreted by the curli biogenesis system. Understanding the curli biogenesis mechanism is critical for developing therapeutic agents for biofilm-related infections. Here we report a systematic study of the curli biogenesis system, highlighted by structural, biochemical and functional analysis of the secretion channel complexes (CsgF-CsgG) with and without the curli substrate. The dual-pore architecture of the CsgF-CsgG complex was observed and used to develop an approach to inhibit the curli secretion by physically reducing the size of the CsgF pore. We further elucidated the assembly of the CsgFG complex with curli components (CsgA and CsgB) and curli-cell association through CsgF. Importantly, the recognition of the CsgA substrate by CsgG was uncovered. Nine crevices outside of the CsgG channel provide specific and highly-conserved recognition sites for CsgA N-terminus. Together with analysis of CsgE, our study provides comprehensive insights into curli biogenesis.


Assuntos
Amiloide/metabolismo , Sistemas de Secreção Bacterianos/química , Sistemas de Secreção Bacterianos/metabolismo , Proteínas de Escherichia coli/metabolismo , Amiloide/antagonistas & inibidores , Sítios de Ligação , Microscopia Crioeletrônica , Escherichia coli K12/efeitos dos fármacos , Escherichia coli K12/metabolismo , Proteínas de Escherichia coli/antagonistas & inibidores , Modelos Moleculares , Mutação , Peptídeos/farmacologia , Ligação Proteica , Conformação Proteica , Multimerização Proteica
10.
PLoS One ; 15(1): e0227227, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31978114

RESUMO

Many conflicting reports about the involvement of serum amyloid P component (SAP) in amyloid diseases have been presented over the years; SAP is known to be a universal component of amyloid aggregates but it has been suggested that it can both induce and suppress amyloid formation. By using our Drosophila model of systemic lysozyme amyloidosis, SAP has previously been shown to reduce the toxicity induced by the expression of the disease-associated lysozyme variant, F57I, in the Drosophila central nervous system. This study further investigates the involvement of SAP in modulating lysozyme toxicity using histochemistry and spectral analyses on the double transgenic WT and F57I lysozyme flies to probe; i) formation of aggregates, ii) morphological differences of the aggregated lysozyme species formed in the presence or absence of SAP, iii) location of lysozyme and iv) co-localisation of lysozyme and SAP in the fly brain. We found that SAP can counteract the toxicity (measured by the reduction in the median survival time) induced by F57I lysozyme by converting toxic F57I species into less toxic amyloid-like structures, as reflected by the spectral changes that p-FTAA undergoes when bound to lysozyme deposits in F57I-F57I-SAP flies as compared to F57I-F57I flies. Indeed, when SAP was introduced to in vitro lysozyme fibril formation, the endpoint fibrils had enhanced ThT fluorescence intensity as compared to lysozyme fibrils alone. This suggests that a general mechanism for SAP's role in amyloid diseases may be to promote the formation of stable, amyloid-like fibrils, thus decreasing the impact of toxic species formed along the aggregation pathway.


Assuntos
Amiloidose/metabolismo , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/metabolismo , Muramidase/metabolismo , Componente Amiloide P Sérico/metabolismo , Amiloide/genética , Amiloide/metabolismo , Amiloide/ultraestrutura , Amiloidose/genética , Amiloidose/patologia , Animais , Animais Geneticamente Modificados , Modelos Animais de Doenças , Proteínas de Drosophila/genética , Drosophila melanogaster/genética , Humanos , Muramidase/genética , Agregados Proteicos , Agregação Patológica de Proteínas/genética , Agregação Patológica de Proteínas/metabolismo , Agregação Patológica de Proteínas/patologia
12.
Chem Commun (Camb) ; 56(15): 2348-2351, 2020 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-31993621

RESUMO

A miniaturized mimic of the active site of a protease, chymotrypsin, was linked to a target recognition unit to generate "Miniature Artificial Proteases" (mAPs). Time-resolved MALDI-TOF data analyses indicated that mAPs cleaved every amide bond between Lys16-Phe20 of the amyloid ß fragment (Aß12-21) and Aß1-40, resulting in inhibition of fibrillization and disruption of the preformed amyloid. Such a platform may offer not only new therapeutic options against various amyloidoses but also novel routes for the selective knockdown of specific proteins.


Assuntos
Amiloide/metabolismo , Quimotripsina/metabolismo , Amiloide/química , Domínio Catalítico , Quimotripsina/química , Humanos , Modelos Moleculares , Estrutura Molecular
13.
Nat Commun ; 11(1): 571, 2020 Jan 29.
Artigo em Inglês | MEDLINE | ID: mdl-31996674

RESUMO

Aggregation of the Tau protein into fibrils defines progression of neurodegenerative diseases, including Alzheimer's Disease. The molecular basis for potentially toxic reactions of Tau aggregates is poorly understood. Here we show that π-stacking by Arginine side-chains drives protein binding to Tau fibrils. We mapped an aggregation-dependent interaction pattern of Tau. Fibrils recruit specifically aberrant interactors characterised by intrinsically disordered regions of atypical sequence features. Arginine residues are key to initiate these aberrant interactions. Crucial for scavenging is the guanidinium group of its side chain, not its charge, indicating a key role of π-stacking chemistry for driving aberrant fibril interactions. Remarkably, despite the non-hydrophobic interaction mode, the molecular chaperone Hsp90 can modulate aberrant fibril binding. Together, our data present a molecular mode of action for derailment of protein-protein interaction by neurotoxic fibrils.


Assuntos
Doença de Alzheimer/metabolismo , Amiloide/metabolismo , Arginina/metabolismo , Ligação Proteica , Proteínas tau/metabolismo , Doença de Alzheimer/genética , Sequência de Aminoácidos , Animais , Arginina/química , Progressão da Doença , Guanidina/metabolismo , Proteínas de Choque Térmico HSP90 , Humanos , Espectrometria de Massas , Chaperonas Moleculares , Agregados Proteicos , Domínios Proteicos , Dobramento de Proteína , Proteoma , Ratos , Análise de Sequência de Proteína , Proteínas tau/química , Proteínas tau/genética
14.
Chemistry ; 26(9): 1893, 2020 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-31961031

RESUMO

Invited for the cover of this issue is the group of András Perczel at Eötvös Loránd University, Budapest, Hungary and colleagues from Osaka University, Japan. The image depicts the amyloid buildup of an Exenatide derivate miniprotein (E5) monitored on a simplified hyperspace. Read the full text of the article at 10.1002/chem.201903826.


Assuntos
Amiloide/metabolismo , Amiloide/química , Modelos Biológicos , Ressonância Magnética Nuclear Biomolecular , Peptídeos/química , Peptídeos/metabolismo , Estrutura Secundária de Proteína , Termodinâmica
15.
Chemistry ; 26(9): 1968-1978, 2020 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-31647140

RESUMO

The amyloid formation of the folded segment of a variant of Exenatide (a marketed drug for type-2 diabetes mellitus) was studied by electronic circular dichroism (ECD) and NMR spectroscopy. We found that the optimum temperature for E5 protein amyloidosis coincides with body temperature and requires well below physiological salt concentration. Decomposition of the ECD spectra and its barycentric representation on the folded-unfolded-amyloid potential energy surface allowed us to monitor the full range of molecular transformation of amyloidogenesis. We identified points of no return (e.g.; T=37 °C, pH 4.1, cE5 =250 µm, cNaCl =50 mm, t>4-6 h) that will inevitably gravitate into the amyloid state. The strong B-type far ultraviolet (FUV)-ECD spectra and an unexpectedly strong near ultraviolet (NUV)-ECD signal (Θ≈275-285   nm ) indicate that the amyloid phase of E5 is built from monomers of quasi-elongated backbone structure (φ≈-145°, ψ≈+145°) with strong interstrand Tyr↔Trp interaction. Misfolded intermediates and the buildup of "toxic" early-stage oligomers leading to self-association were identified and monitored as a function of time. Results indicate that the amyloid transition is triggered by subtle misfolding of the α-helix, exposing aromatic and hydrophobic side chains that may provide the first centers for an intermolecular reorganization. These initial clusters provide the spatial closeness and sufficient time for a transition to the ß-structured amyloid nucleus, thus the process follows a nucleated growth mechanism.


Assuntos
Amiloide/metabolismo , Sequência de Aminoácidos , Amiloide/química , Dicroísmo Circular , Concentração de Íons de Hidrogênio , Simulação de Dinâmica Molecular , Ressonância Magnética Nuclear Biomolecular , Peptídeos/química , Conformação Proteica , Dobramento de Proteína , Temperatura
16.
J Photochem Photobiol B ; 202: 111671, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31731076

RESUMO

As a molecular chaperone, ß-casein is difficult to form amyloid fibrils under physiological conditions due to its chaperone activity. Heparan sulfate (HS) has drawn attention of technologists all over the word because of its relation to amyloid deposits in some amyloidosis diseases. For better understanding the relationship between the ß-casein and HS, the multi-spectroscopic studies were employed. The data of thioflavin T (ThT) binding assay, transmission electron microscopy (TEM) and circular dichroism (CD) demonstrated that HS promoted fibril formation by ß-casein in the amount and the growth speed. The results of steady-state UV-vis absorption spectra, fluorescence spectroscopy and fluorescence lifetime revealed that the ß-casein-HS complexes were formed and HS quenched the fluorescence of ß-casein by a static quenching mechanism. On the basis of fluorescence analysis, the value of binding constant was equal to 1.17 × 107 L mol-1 at 338.15 K and there was about one binding site between them. According to thermodynamic parameters obtained, it was deduced that a spontaneous reaction happened, and protein-ligand complex was stabilized by hydrogen bonds and hydrophobic interaction. Furthermore, using fluorescence resonance energy transfer (FRET) assay, the value of binding distance between HS and Trp143 of ß-casein was calculated to be 0.93 nm. Finally, on the basis of synchronous fluorescence experiment, the polarity increasing and hydrophobicity decreasing around Trp143 occurred during the period of fibril formation by ß-casein.


Assuntos
Amiloide/metabolismo , Caseínas/química , Heparitina Sulfato/química , Amiloide/química , Animais , Sítios de Ligação , Caseínas/metabolismo , Bovinos , Dicroísmo Circular , Transferência Ressonante de Energia de Fluorescência , Heparitina Sulfato/metabolismo , Interações Hidrofóbicas e Hidrofílicas , Microscopia Eletrônica de Transmissão , Ligação Proteica , Termodinâmica
17.
Chem Biol Interact ; 315: 108884, 2020 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-31678113

RESUMO

Quinolinic acid (QA) known as a neuro-active metabolite associated with the kynurenine pathway. At high concentrations, QA is often involved in the initiation and development of several human neurologic diseases, like Alzheimer's disease. Because of the QA action as the NMDA receptor, it is considered as a potent excitotoxin in vivo. Since it is probable that different mechanisms are employed by QA, activation of NMDA receptors cannot fully explain the revealed toxicity and it is even believed that there are multiple unknown mechanisms/targets leading to QA cytotoxicity. Herein we report accelerated amyloid oligomerization of 1N4R Tau under the effect of QA, in vitro, then the molecular structure, morphology and toxicity of the protein aggregate were documented by using various theoretical/experimental approaches. The possible mechanism of action of QA-induced Tau oligomerization has also been explored.


Assuntos
Amiloide/metabolismo , Neurotoxinas/efeitos adversos , Agregados Proteicos/efeitos dos fármacos , Piridinas/efeitos adversos , Ácido Quinolínico/efeitos adversos , Doença de Alzheimer/metabolismo , Humanos , Cinurenina/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismo
18.
Biochim Biophys Acta Proteins Proteom ; 1868(1): 140283, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31526870

RESUMO

The abnormal aggregation of human islet amyloid polypeptide (hIAPP) is a crucial pathogenic factor associated with type 2 diabetes (T2D). The development of effective inhibitors to prevent hIAPP aggregation is a common therapeutic strategy against T2D. Lithospermic acid (LA) is a natural compound with diversified biological activities. In this study, electrospray ionization coupled with ion mobility-mass spectrometry, thioflavin T fluorescence assay, Congo red binding assay, Nile red fluorescence assay, circular dichroism spectroscopy, transmission electron microscopy, cell toxicity, lactate dehydrogenase assay (LDH) assay and molecular docking were combined to explore the influence of LA on hIAPP aggregation. Results showed that LA had favorable binding affinity to hIAPP and formed hIAPP-LA complexes, which could alter the relative abundance of the compact and extended conformers and promoted the transition of extended structures to compact conformers. LA also displayed strong inhibitory actions on fibrillation and potential protective effects against hIAPP-induced cell toxicity. Therefore, the obtained results were useful to understand the possible inhibitory mechanism of LA on hIAPP aggregation and provided valuable reference for the screening of potent amyloid inhibitors.


Assuntos
Amiloide/metabolismo , Benzofuranos/farmacologia , Depsídeos/farmacologia , Polipeptídeo Amiloide das Ilhotas Pancreáticas/metabolismo , Animais , Morte Celular/efeitos dos fármacos , Linhagem Celular , Humanos , Polipeptídeo Amiloide das Ilhotas Pancreáticas/química , Simulação de Acoplamento Molecular , Conformação Proteica , Ratos
19.
Biophys Chem ; 256: 106281, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31756663

RESUMO

Timely and accurate diagnosis of Alzheimer's disease (AD) remains a major challenge in the medical arena. ß-amyloid (Aß) imaging techniques such as positron emission tomography and single photon emission computed tomography require the use of an imaging probe. To date, only flutemetamol, florbetaben and florbetapir have been approved for clinical use as imaging probes. Design of imaging probes requires a detailed understanding of disease mechanism(s) and receptor-ligand interaction. In this study, molecular docking, molecular dynamics and binding free energies were used to investigate the multiple binding sites exhibited by ß-amyloid fibrils. Protein atomic models 2BEG, 5KK3, 2M4J, 2LMN, 5OQV, 2NAO, 2MVX and 2MXU (protein databank codes) were used to investigate the nature and location of binding sites and binding profiles of selected molecules with known affinities. Although amyloid fibrils are known to have multiple binding sites, we demonstrated that model 2MXU possesses one site which is druggable and can bind with common scaffolds currently being used in the imaging of amyloid fibrils. Models 2NAO, 5KK3 and 2M4J revealed that even though multiple sites may be available in some fibrils, the entire protein may not have a druggable site. Molecular dynamics revealed atomic models 2MXU and 2MVX to be the least flexible among the list. The outcomes of this investigation can be translated to assist in designing novel molecules that can be used for brain imaging in Alzheimer's disease.


Assuntos
Amiloide/química , Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , Doença de Alzheimer/metabolismo , Doença de Alzheimer/patologia , Amiloide/metabolismo , Sítios de Ligação , Bases de Dados de Proteínas , Humanos , Ligantes , Ligação Proteica , Estrutura Terciária de Proteína
20.
Phys Chem Chem Phys ; 22(3): 1543-1556, 2020 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-31872820

RESUMO

Amyloid aggregation modulators offer a promising treatment strategy for Alzheimer's disease (AD). We have recently reported a novel di-triazole based compound 6n as a multi-target-directed ligand (MTDL) against AD. 6n effectively inhibits Aß42 aggregation, metal-induced Aß42 aggregation, reactive oxygen species (ROS) generation, and rescues SH-SY5Y cells from Aß42 induced neurotoxicity. However, the underlying inhibitory mechanism remains uncovered. In this regard, molecular dynamics (MD) simulations were performed to understand the effect of 6n on the structure and stability of monomeric Aß42 and a pentameric protofibril structure of Aß42. Compound 6n binds preferably to the central hydrophobic core (CHC) and C-terminal regions of the Aß42 monomer as well as the protofibril structure. The secondary structure analysis suggests that 6n prevents the aggregation of the Aß42 monomer and disaggregates Aß42 protofibrils by sustaining the helical content in the Aß42 monomer and converting the ß-sheet into random coil conformation in the Aß42 protofibril structure. A significant decrease in the average number of hydrogen bonds, binding affinity, and residue-residue contacts between chains D-E of the Aß42 protofibril in the presence of 6n indicates destabilization of the Aß42 protofibril structure. The MM-PBSA (molecular mechanics Poisson-Boltzmann surface area) analysis highlighted favourable binding free energy (ΔGbinding) for the Aß42 monomer-6n and Aß42 protofibril-6n complex. Overall, MD results highlighted that 6n stabilizes the native α-helix conformation of the Aß42 monomer and induces a sizable destabilization in the Aß42 protofibril structure. This work provides theoretical insights into the inhibitory mechanism of 6n against amyloid aggregation and will be beneficial as a molecular guide for structure-based drug design against AD.


Assuntos
Peptídeos beta-Amiloides/metabolismo , Fragmentos de Peptídeos/metabolismo , Triazóis/química , Amiloide/química , Amiloide/metabolismo , Peptídeos beta-Amiloides/química , Simulação de Dinâmica Molecular , Fragmentos de Peptídeos/química , Ligação Proteica , Conformação Proteica em alfa-Hélice , Estabilidade Proteica
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