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1.
Nat Commun ; 12(1): 2073, 2021 04 06.
Artigo em Inglês | MEDLINE | ID: mdl-33824313

RESUMO

Phenylketonuria (PKU) is caused by autosomal recessive variants in phenylalanine hydroxylase (PAH), leading to systemic accumulation of L-phenylalanine (L-Phe) that may reach neurotoxic levels. A homozygous Pah-R261Q mouse, with a highly prevalent misfolding variant in humans, reveals the expected hepatic PAH activity decrease, systemic L-Phe increase, L-tyrosine and L-tryptophan decrease, and tetrahydrobiopterin-responsive hyperphenylalaninemia. Pah-R261Q mice also present unexpected traits, including altered lipid metabolism, reduction of liver tetrahydrobiopterin content, and a metabolic profile indicative of oxidative stress. Pah-R261Q hepatic tissue exhibits large ubiquitin-positive, amyloid-like oligomeric aggregates of mutant PAH that colocalize with selective autophagy markers. Together, these findings reveal that PKU, customarily considered a loss-of-function disorder, can also have toxic gain-of-function contribution from protein misfolding and aggregation. The proteostasis defect and concomitant oxidative stress may explain the prevalence of comorbid conditions in adult PKU patients, placing this mouse model in an advantageous position for the discovery of mutation-specific biomarkers and therapies.


Assuntos
Amiloide/metabolismo , Fígado/enzimologia , Mutação/genética , Estresse Oxidativo , Fenilalanina Hidroxilase/genética , Agregados Proteicos , Animais , Autofagia , Biomarcadores/metabolismo , Peso Corporal , Cruzamento , Feminino , Regulação da Expressão Gênica , Genótipo , Metabolismo dos Lipídeos , Fígado/patologia , Masculino , Metaboloma , Camundongos , Proteínas Mutantes/metabolismo , Neurotransmissores/metabolismo , Estresse Oxidativo/genética , Fenilalanina/metabolismo , Fenilalanina Hidroxilase/metabolismo , Fenilcetonúrias/enzimologia , Pterinas/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Respiração , Ubiquitina/metabolismo , Ubiquitinação
2.
Chemistry ; 27(19): 6015-6027, 2021 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-33666306

RESUMO

Many (poly-)phenolic natural products, for example, curcumin and taxifolin, have been studied for their activity against specific hallmarks of neurodegeneration, such as amyloid-ß 42 (Aß42) aggregation and neuroinflammation. Due to their drawbacks, arising from poor pharmacokinetics, rapid metabolism, and even instability in aqueous medium, the biological activity of azobenzene compounds carrying a pharmacophoric catechol group, which have been designed as bioisoteres of curcumin has been examined. Molecular simulations reveal the ability of these compounds to form a hydrophobic cluster with Aß42, which adopts different folds, affecting the propensity to populate fibril-like conformations. Furthermore, the curcumin bioisosteres exceeded the parent compound in activity against Aß42 aggregation inhibition, glutamate-induced intracellular oxidative stress in HT22 cells, and neuroinflammation in microglial BV-2 cells. The most active compound prevented apoptosis of HT22 cells at a concentration of 2.5 µm (83 % cell survival), whereas curcumin only showed very low protection at 10 µm (21 % cell survival).


Assuntos
Amiloidose , Curcumina , Amiloide/metabolismo , Peptídeos beta-Amiloides/metabolismo , Curcumina/farmacologia , Humanos , Estresse Oxidativo
3.
Adv Pharmacol ; 90: 239-251, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33706935

RESUMO

Presenilin 1 (PS1) is an intramembrane protease, the active subunit of the γ-secretase complex. Its well-studied function is the amyloidogenic cleavage of the C-terminal fragment of the amyloid precursor protein, also known as C99, to produce the Abeta peptide. Recent findings from the Greengard laboratory suggest that PS1 also have anti-amyloidogenic activities, which reduce Abeta levels. First, it redirects APP-C99 toward autophagic degradation, lowering the amount that can be converted into Abeta. The protein kinase CK1γ2 phosphorylates PS1 at Ser367. Phosphorylated PS1 at this position interacts with Annexin A2, which, in turn, interacts with the lysosomal N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) Vamp8. Annexin A2 facilitates the binding of Vamp8 to the autophagosomal SNARE Syntaxin 17 to modulate the fusion of autophagosomes with lysosomes. Thus, PS1 phosphorylated at Ser367 has an anti-amyloidogenic function, promoting autophagosome-lysosome fusion and increasing C99 degradation. Second, it enhances the ability of microglia to phagocyte and degrade extracellular Abeta oligomer, through regulating the expression of the lysosomal master regulator TFEB. Thus, PS1 has a role in both the production and the clearance of Abeta. Drugs designed to activate CK1γ2 and increase the level of PS1 phosphorylated at Ser367 should be useful in the treatment of Alzheimer's disease.


Assuntos
Amiloide/metabolismo , Presenilina-1/metabolismo , Secretases da Proteína Precursora do Amiloide/metabolismo , Peptídeos beta-Amiloides/metabolismo , Animais , Autofagia , Humanos , Degeneração Neural/patologia
4.
Int J Mol Sci ; 22(4)2021 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-33672696

RESUMO

BACKGROUND: Alzheimer's disease (AD) is a progressive neurodegenerative disorder affecting many individuals worldwide with no effective treatment to date. AD is characterized by the formation of senile plaques and neurofibrillary tangles, followed by neurodegeneration, which leads to cognitive decline and eventually death. INTRODUCTION: In AD, pathological changes occur many years before disease onset. Since disease-modifying therapies may be the most beneficial in the early stages of AD, biomarkers for the early diagnosis and longitudinal monitoring of disease progression are essential. Multiple imaging techniques with associated biomarkers are used to identify and monitor AD. AIM: In this review, we discuss the contemporary early diagnosis and longitudinal monitoring of AD with imaging techniques regarding their diagnostic utility, benefits and limitations. Additionally, novel techniques, applications and biomarkers for AD research are assessed. FINDINGS: Reduced hippocampal volume is a biomarker for neurodegeneration, but atrophy is not an AD-specific measure. Hypometabolism in temporoparietal regions is seen as a biomarker for AD. However, glucose uptake reflects astrocyte function rather than neuronal function. Amyloid-ß (Aß) is the earliest hallmark of AD and can be measured with positron emission tomography (PET), but Aß accumulation stagnates as disease progresses. Therefore, Aß may not be a suitable biomarker for monitoring disease progression. The measurement of tau accumulation with PET radiotracers exhibited promising results in both early diagnosis and longitudinal monitoring, but large-scale validation of these radiotracers is required. The implementation of new processing techniques, applications of other imaging techniques and novel biomarkers can contribute to understanding AD and finding a cure. CONCLUSIONS: Several biomarkers are proposed for the early diagnosis and longitudinal monitoring of AD with imaging techniques, but all these biomarkers have their limitations regarding specificity, reliability and sensitivity. Future perspectives. Future research should focus on expanding the employment of imaging techniques and identifying novel biomarkers that reflect AD pathology in the earliest stages.


Assuntos
Doença de Alzheimer/diagnóstico por imagem , Doença de Alzheimer/diagnóstico , Diagnóstico Precoce , Neuroimagem , Doença de Alzheimer/patologia , Amiloide/metabolismo , Biomarcadores/metabolismo , Humanos , Estudos Longitudinais
5.
Biochem Biophys Res Commun ; 554: 94-98, 2021 05 21.
Artigo em Inglês | MEDLINE | ID: mdl-33789211

RESUMO

The post-infection of COVID-19 includes a myriad of neurologic symptoms including neurodegeneration. Protein aggregation in brain can be considered as one of the important reasons behind the neurodegeneration. SARS-CoV-2 Spike S1 protein receptor binding domain (SARS-CoV-2 S1 RBD) binds to heparin and heparin binding proteins. Moreover, heparin binding accelerates the aggregation of the pathological amyloid proteins present in the brain. In this paper, we have shown that the SARS-CoV-2 S1 RBD binds to a number of aggregation-prone, heparin binding proteins including Aß, α-synuclein, tau, prion, and TDP-43 RRM. These interactions suggests that the heparin-binding site on the S1 protein might assist the binding of amyloid proteins to the viral surface and thus could initiate aggregation of these proteins and finally leads to neurodegeneration in brain. The results will help us to prevent future outcomes of neurodegeneration by targeting this binding and aggregation process.


Assuntos
Amiloide/metabolismo , Heparina/metabolismo , Doenças Neurodegenerativas/metabolismo , Agregação Patológica de Proteínas , Glicoproteína da Espícula de Coronavírus/metabolismo , Peptídeos beta-Amiloides/metabolismo , Encéfalo/metabolismo , Encéfalo/patologia , Encéfalo/virologia , Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/metabolismo , Humanos , Simulação de Acoplamento Molecular , Doenças Neurodegenerativas/virologia , Príons/metabolismo , Ligação Proteica , /metabolismo , Glicoproteína da Espícula de Coronavírus/química , alfa-Sinucleína/metabolismo , Proteínas tau/metabolismo
6.
Int J Mol Sci ; 22(4)2021 Feb 18.
Artigo em Inglês | MEDLINE | ID: mdl-33670754

RESUMO

Alzheimer's disease (AD) is the most common neurodegenerative disease worldwide. Histopathologically, AD presents with two hallmarks: neurofibrillary tangles (NFTs), and aggregates of amyloid ß peptide (Aß) both in the brain parenchyma as neuritic plaques, and around blood vessels as cerebral amyloid angiopathy (CAA). According to the vascular hypothesis of AD, vascular risk factors can result in dysregulation of the neurovascular unit (NVU) and hypoxia. Hypoxia may reduce Aß clearance from the brain and increase its production, leading to both parenchymal and vascular accumulation of Aß. An increase in Aß amplifies neuronal dysfunction, NFT formation, and accelerates neurodegeneration, resulting in dementia. In recent decades, therapeutic approaches have attempted to decrease the levels of abnormal Aß or tau levels in the AD brain. However, several of these approaches have either been associated with an inappropriate immune response triggering inflammation, or have failed to improve cognition. Here, we review the pathogenesis and potential therapeutic targets associated with dysfunction of the NVU in AD.


Assuntos
Doença de Alzheimer/fisiopatologia , Encéfalo/irrigação sanguínea , Encéfalo/fisiopatologia , Doença de Alzheimer/tratamento farmacológico , Doença de Alzheimer/patologia , Amiloide/metabolismo , Animais , Barreira Hematoencefálica/patologia , Barreira Hematoencefálica/fisiopatologia , Encéfalo/patologia , Humanos , Terapia de Alvo Molecular
7.
Nat Commun ; 12(1): 1627, 2021 03 12.
Artigo em Inglês | MEDLINE | ID: mdl-33712586

RESUMO

RIPK3 amyloid complex plays crucial roles during TNF-induced necroptosis and in response to immune defense in both human and mouse. Here, we have structurally characterized mouse RIPK3 homogeneous self-assembly using solid-state NMR, revealing a well-ordered N-shaped amyloid core structure featured with 3 parallel in-register ß-sheets. This structure differs from previously published human RIPK1/RIPK3 hetero-amyloid complex structure, which adopted a serpentine fold. Functional studies indicate both RIPK1-RIPK3 binding and RIPK3 amyloid formation are essential but not sufficient for TNF-induced necroptosis. The structural integrity of RIPK3 fibril with three ß-strands is necessary for signaling. Molecular dynamics simulations with a mouse RIPK1/RIPK3 model indicate that the hetero-amyloid is less stable when adopting the RIPK3 fibril conformation, suggesting a structural transformation of RIPK3 from RIPK1-RIPK3 binding to RIPK3 amyloid formation. This structural transformation would provide the missing link connecting RIPK1-RIPK3 binding to RIPK3 homo-oligomer formation in the signal transduction.


Assuntos
Amiloide/metabolismo , Amiloide/ultraestrutura , Necroptose/fisiologia , Proteína Serina-Treonina Quinases de Interação com Receptores/química , Proteína Serina-Treonina Quinases de Interação com Receptores/metabolismo , Animais , Benzotiazóis , Sobrevivência Celular , Drosophila , Herpesviridae , Humanos , Camundongos , Simulação de Dinâmica Molecular , Necroptose/genética , Conformação Proteica , Ratos , Proteína Serina-Treonina Quinases de Interação com Receptores/genética , Alinhamento de Sequência , Análise de Sequência de Proteína , Transdução de Sinais
8.
Nat Commun ; 12(1): 1620, 2021 03 12.
Artigo em Inglês | MEDLINE | ID: mdl-33712624

RESUMO

Amyotrophic lateral sclerosis and several other neurodegenerative diseases are associated with brain deposits of amyloid-like aggregates formed by the C-terminal fragments of TDP-43 that contain the low complexity domain of the protein. Here, we report the cryo-EM structure of amyloid formed from the entire TDP-43 low complexity domain in vitro at pH 4. This structure reveals single protofilament fibrils containing a large (139-residue), tightly packed core. While the C-terminal part of this core region is largely planar and characterized by a small proportion of hydrophobic amino acids, the N-terminal region contains numerous hydrophobic residues and has a non-planar backbone conformation, resulting in rugged surfaces of fibril ends. The structural features found in these fibrils differ from those previously found for fibrils generated from short protein fragments. The present atomic model for TDP-43 LCD fibrils provides insight into potential structural perturbations caused by phosphorylation and disease-related mutations.


Assuntos
Amiloide/química , Microscopia Crioeletrônica/métodos , Proteínas de Ligação a DNA/química , Amiloide/genética , Amiloide/metabolismo , Esclerose Amiotrófica Lateral/metabolismo , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Interações Hidrofóbicas e Hidrofílicas , Modelos Moleculares , Mutação Puntual , Conformação Proteica
9.
Nat Commun ; 12(1): 1814, 2021 03 22.
Artigo em Inglês | MEDLINE | ID: mdl-33753734

RESUMO

The self-assembly of α-synuclein (αS) into intraneuronal inclusion bodies is a key characteristic of Parkinson's disease. To define the nature of the species giving rise to neuronal damage, we have investigated the mechanism of action of the main αS populations that have been observed to form progressively during fibril growth. The αS fibrils release soluble prefibrillar oligomeric species with cross-ß structure and solvent-exposed hydrophobic clusters. αS prefibrillar oligomers are efficient in crossing and permeabilize neuronal membranes, causing cellular insults. Short fibrils are more neurotoxic than long fibrils due to the higher proportion of fibrillar ends, resulting in a rapid release of oligomers. The kinetics of released αS oligomers match the observed kinetics of toxicity in cellular systems. In addition to previous evidence that αS fibrils can spread in different brain areas, our in vitro results reveal that αS fibrils can also release oligomeric species responsible for an immediate dysfunction of the neurons in the vicinity of these species.


Assuntos
Amiloide/metabolismo , Corpos de Inclusão/metabolismo , Neurônios/metabolismo , alfa-Sinucleína/metabolismo , Amiloide/química , Animais , Cálcio/metabolismo , Linhagem Celular Tumoral , Células Cultivadas , Humanos , Cinética , Microscopia Confocal , Doença de Parkinson/metabolismo , Agregação Patológica de Proteínas , Multimerização Proteica , Ratos Sprague-Dawley , alfa-Sinucleína/química
10.
Int J Mol Sci ; 22(4)2021 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-33546497

RESUMO

Amyloid formation is associated with many incurable diseases. For some of these, sporadic cases are much more common than familial ones. Some reports point to the role of somatic cell mosaicism in these cases via origination of amyloids in a limited number of cells, which can then spread through tissues. However, specific types of sporadic mutations responsible for such effects are unknown. In order to identify mutations capable of increasing the de novo appearance of amyloids, we searched for such mutants in the yeast prionogenic protein Sup35. We introduced to yeast cells an additional copy of the SUP35 gene with mutated amyloidogenic domain and observed that some nonsense mutations increased the incidence of prions by several orders of magnitude. This effect was related to exposure at the C-terminus of an internal amyloidogenic region of Sup35. We also discovered that SUP35 mRNA could undergo splicing, although inefficiently, causing appearance of a shortened Sup35 isoform lacking its functional domain, which was also highly prionogenic. Our data suggest that truncated forms of amyloidogenic proteins, resulting from nonsense mutations or alternative splicing in rare somatic cells, might initiate spontaneous localized formation of amyloids, which can then spread, resulting in sporadic amyloid disease.


Assuntos
Amiloide/metabolismo , Códon sem Sentido , Príons/genética , Príons/metabolismo , Amiloidose/genética , Amiloidose/metabolismo , Amiloidose/patologia , Proteínas Fúngicas/química , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Espectrometria de Massas , Príons/química , Agregados Proteicos , Processamento de RNA
11.
Int J Mol Sci ; 22(4)2021 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-33579016

RESUMO

Protein aggregation into amyloid fibrils is linked to multiple disorders. The understanding of how natively non-harmful proteins convert to these highly cytotoxic amyloid aggregates is still not sufficient, with new ideas and hypotheses being presented each year. Recently it has been shown that more than one type of protein aggregates may co-exist in the affected tissue of patients suffering from amyloid-related disorders, sparking the idea that amyloid aggregates formed by one protein may induce another protein's fibrillization. In this work, we examine the effect that lysozyme fibrils have on insulin amyloid aggregation. We show that not only do lysozyme fibrils affect insulin nucleation, but they also alter the mechanism of its aggregation.


Assuntos
Amiloide/metabolismo , Insulina/metabolismo , Muramidase/metabolismo , Agregação Patológica de Proteínas/metabolismo , Amiloide/ultraestrutura , Animais , Galinhas , Humanos , Agregados Proteicos , Proteínas Recombinantes/metabolismo
12.
J Frailty Aging ; 10(2): 160-167, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33575706

RESUMO

BACKGROUND: Frailty and cognitive impairment are common manifestations of the ageing process and are closely related. But the mechanisms linking aging, physical frailty, and cognitive disorders, are complex and remain unclear. OBJECTIVES: We aim to explore the role of cerebral amyloid pathology, but also a range of nutritional, physical, biological or brain-aging marker in the development of cognitive frailty. METHOD: COGFRAIL study is a monocentric prospective study of frail older patients with an objective cognitive impairment (Clinical Dementia Rating Scale global score at 0.5 or 1). Three-hundred-and-twenty-one patients are followed up every 6 months, for 2 years. Clinical assessment at baseline and during follow-up included frailty, physical, mood, sensory, nutritional, and cognitive assessment (with a set of neuropsychological tests). Cerebral amyloid pathology is measured by amyloid Positron Emission Tomography (PET) or amyloid-ß-1-42 level in cerebrospinal fluid. Brain magnetic resonance imaging, measurement of body composition using Dual X Ray Absorptiometry and blood sampling are performed. The main outcome of the study is to assess the prevalence of positive cerebral amyloid status according to amyloid PET or amyloid-ß-1-42 level CSF. Secondary outcomes included biological, nutritional, MRI imaging, cognitive, clinical, physical and body composition markers to better understand the mechanisms of cognitive frailty. PERSPECTIVE: COGFRAIL study will give the opportunity to better understand the link between Gerosciences, frailty, cognitive impairment, and Alzheimer's disease, and to better characterize the physical and cognitive trajectories of frail older adults according to their amyloid status. Understanding the relationship between physical frailty and cognitive impairment is a prerequisite for the development of new interventions that could prevent and treat both conditions.


Assuntos
Amiloide , Cognição , Disfunção Cognitiva , Idoso Fragilizado , Idoso , Idoso de 80 Anos ou mais , Amiloide/metabolismo , Biomarcadores/metabolismo , Cognição/fisiologia , Disfunção Cognitiva/diagnóstico , Humanos , Estudos Prospectivos
13.
Nat Commun ; 12(1): 1013, 2021 02 12.
Artigo em Inglês | MEDLINE | ID: mdl-33579941

RESUMO

Systemic AA amyloidosis is a world-wide occurring protein misfolding disease of humans and animals. It arises from the formation of amyloid fibrils from serum amyloid A (SAA) protein. Using cryo electron microscopy we here show that amyloid fibrils which were purified from AA amyloidotic mice are structurally different from fibrils formed from recombinant SAA protein in vitro. Ex vivo amyloid fibrils consist of fibril proteins that contain more residues within their ordered parts and possess a higher ß-sheet content than in vitro fibril proteins. They are also more resistant to proteolysis than their in vitro formed counterparts. These data suggest that pathogenic amyloid fibrils may originate from proteolytic selection, allowing specific fibril morphologies to proliferate and to cause damage to the surrounding tissue.


Assuntos
Amiloide/metabolismo , Amiloidose/metabolismo , Proteína Amiloide A Sérica/metabolismo , Animais , Microscopia Crioeletrônica , Camundongos , Modelos Moleculares , Conformação Proteica em Folha beta , Proteínas Recombinantes , Proteína Amiloide A Sérica/genética
14.
Nat Chem Biol ; 17(3): 237-245, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33432239

RESUMO

Amyloid aggregation, which disrupts protein homeostasis, is a common pathological event occurring in human neurodegenerative diseases (NDs). Numerous evidences have shown that the structural diversity, so-called polymorphism, is decisive to the amyloid pathology and is closely associated with the onset, progression, and phenotype of ND. But how could one protein form so many stable structures? Recently, atomic structural evidence has been rapidly mounting to depict the involvement of chemical modifications in the amyloid fibril formation. In this Perspective, we aim to present a hierarchical regulation of chemical modifications including covalent post-translational modifications (PTMs) and noncovalent cofactor binding in governing the polymorphic amyloid formation, based mainly on the latest α-synuclein and Tau fibril structures. We hope to emphasize the determinant role of chemical modifications in amyloid assembly and pathology and to evoke chemical biological approaches to lead the fundamental and therapeutic research on protein amyloid state and the associated NDs.


Assuntos
Amiloide/química , Proteínas de Ligação a DNA/química , Processamento de Proteína Pós-Traducional , alfa-Sinucleína/química , Proteínas tau/química , Acetilação , Doença de Alzheimer/genética , Doença de Alzheimer/metabolismo , Doença de Alzheimer/patologia , Amiloide/metabolismo , Proteínas de Ligação a DNA/metabolismo , Humanos , Doença de Huntington/genética , Doença de Huntington/metabolismo , Doença de Huntington/patologia , Modelos Moleculares , Doença de Parkinson/genética , Doença de Parkinson/metabolismo , Doença de Parkinson/patologia , Fosforilação , Poli Adenosina Difosfato Ribose/química , Poli Adenosina Difosfato Ribose/metabolismo , Agregados Proteicos , Ligação Proteica , Domínios e Motivos de Interação entre Proteínas , Estrutura Secundária de Proteína , alfa-Sinucleína/metabolismo , Proteínas tau/metabolismo
16.
Int J Mol Sci ; 22(2)2021 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-33450960

RESUMO

This work investigated in vitro aggregation and amyloid properties of skeletal myosin binding protein-C (sMyBP-C) interacting in vivo with proteins of thick and thin filaments in the sarcomeric A-disc. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) found a rapid (5-10 min) formation of large (>2 µm) aggregates. sMyBP-C oligomers formed both at the initial 5-10 min and after 16 h of aggregation. Small angle X-ray scattering (SAXS) and DLS revealed sMyBP-C oligomers to consist of 7-10 monomers. TEM and atomic force microscopy (AFM) showed sMyBP-C to form amorphous aggregates (and, to a lesser degree, fibrillar structures) exhibiting no toxicity on cell culture. X-ray diffraction of sMyBP-C aggregates registered reflections attributed to a cross-ß quaternary structure. Circular dichroism (CD) showed the formation of the amyloid-like structure to occur without changes in the sMyBP-C secondary structure. The obtained results indicating a high in vitro aggregability of sMyBP-C are, apparently, a consequence of structural features of the domain organization of proteins of this family. Formation of pathological amyloid or amyloid-like sMyBP-C aggregates in vivo is little probable due to amino-acid sequence low identity (<26%), alternating ordered/disordered regions in the protein molecule, and S-S bonds providing for general stability.


Assuntos
Amiloide/química , Amiloide/metabolismo , Proteínas de Transporte/química , Proteínas de Transporte/metabolismo , Agregados Proteicos , Sequência de Aminoácidos , Amiloide/ultraestrutura , Cromatografia Líquida de Alta Pressão , Dicroísmo Circular , Difusão Dinâmica da Luz , Técnicas In Vitro , Cinética , Espectrometria de Massas , Modelos Moleculares , Agregação Patológica de Proteínas , Conformação Proteica , Relação Estrutura-Atividade , Difração de Raios X
17.
Int J Mol Sci ; 22(3)2021 Jan 27.
Artigo em Inglês | MEDLINE | ID: mdl-33513738

RESUMO

The amyloid-ß (Aß) peptides are associated with two prominent diseases in the brain, Alzheimer's disease (AD) and cerebral amyloid angiopathy (CAA). Aß42 is the dominant component of cored parenchymal plaques associated with AD, while Aß40 is the predominant component of vascular amyloid associated with CAA. There are familial CAA mutations at positions Glu22 and Asp23 that lead to aggressive Aß aggregation, drive vascular amyloid deposition and result in degradation of vascular membranes. In this study, we compared the transition of the monomeric Aß40-WT peptide into soluble oligomers and fibrils with the corresponding transitions of the Aß40-Dutch (E22Q), Aß40-Iowa (D23N) and Aß40-Dutch, Iowa (E22Q, D23N) mutants. FTIR measurements show that in a fashion similar to Aß40-WT, the familial CAA mutants form transient intermediates with anti-parallel ß-structure. This structure appears before the formation of cross-ß-sheet fibrils as determined by thioflavin T fluorescence and circular dichroism spectroscopy and occurs when AFM images reveal the presence of soluble oligomers and protofibrils. Although the anti-parallel ß-hairpin is a common intermediate on the pathway to Aß fibrils for the four peptides studied, the rate of conversion to cross-ß-sheet fibril structure differs for each.


Assuntos
Doença de Alzheimer/metabolismo , Peptídeos beta-Amiloides/química , Amiloide/química , Angiopatia Amiloide Cerebral/genética , Amiloide/metabolismo , Peptídeos beta-Amiloides/genética , Peptídeos beta-Amiloides/metabolismo , Benzotiazóis , Angiopatia Amiloide Cerebral/metabolismo , Dicroísmo Circular , Fluorescência , Microscopia de Força Atômica , Mutação , Placa Amiloide/genética , Placa Amiloide/metabolismo , Conformação Proteica em Folha beta/genética , Espectroscopia de Infravermelho com Transformada de Fourier
18.
ACS Appl Mater Interfaces ; 13(4): 4894-4904, 2021 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-33486955

RESUMO

Chemical and physical properties of nanobio interface substantially affect the conformational transitions of adjacent biomolecules. Previous studies have reported the chiral effect and charge effect of nanobio interface on the misfolding, aggregation, and fibrillation of amyloid protein. However, the isomeric effect of nanobio interface on protein/peptides amyloidosis is still unclear. Here, three isomeric nanobio interfaces were designed and fabricated based on the same sized gold nanoclusters (AuNCs) modified with 4-mercaptobenzoic acid (p-MBA), 3-mercaptobenzoic acid (m-MBA), and 2-mercaptobenzoic acid (o-MBA). Then three isomeric AuNCs were employed as models to explore the isomeric effect on the misfolding, aggregation, and fibrillation of Aß40 at nanobio interfaces. Site-specific replacement experiments on the basis of theoretical analysis revealed the possible mechanism of Aß40 interacting with isomeric ligands of AuNCs at the nanobio interfaces. The distance and orientation of -COOH group from the surface of AuNCs can affect the electrostatic interaction between isomeric ligands and the positively charged residues (R5, K16, and K28) of Aß40, which may affect the inhibition efficiency of isomeric AuNCs on protein amyloidosis. Actually, the amyloid fibrillation kinetics results together with atomic force microscope (AFM) images, dynamic light scattering (DLS) results and circular dichroism (CD) spectra indeed proved that all the three isomeric AuNCs could inhibit the misfolding, aggregation and fibrillation of Aß40 in a dose-dependent manner, and the inhibition efficiency was definitely different from each other. The inhibition efficiency of o-MBA-AuNCs was higher than that of m-MBA-AuNCs and p-MBA-AuNCs at the same dosage. These results provide an insight for isomeric effect at nanobio interfaces, and open an avenue for structure-based nanodrug design target Alzheimer's disease (AD) and even other protein conformational diseases.


Assuntos
Peptídeos beta-Amiloides/antagonistas & inibidores , Amiloide/antagonistas & inibidores , Benzoatos/farmacologia , Ouro/farmacologia , Fragmentos de Peptídeos/antagonistas & inibidores , Agregados Proteicos/efeitos dos fármacos , Salicilatos/farmacologia , Compostos de Sulfidrila/farmacologia , Doença de Alzheimer/tratamento farmacológico , Doença de Alzheimer/metabolismo , Amiloide/química , Amiloide/metabolismo , Amiloide/ultraestrutura , Peptídeos beta-Amiloides/química , Peptídeos beta-Amiloides/metabolismo , Benzoatos/química , Ouro/química , Humanos , Isomerismo , Nanopartículas Metálicas/química , Fragmentos de Peptídeos/química , Fragmentos de Peptídeos/metabolismo , Dobramento de Proteína/efeitos dos fármacos , Salicilatos/química , Compostos de Sulfidrila/química
19.
Clin Nucl Med ; 46(3): e133-e140, 2021 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-33512838

RESUMO

PURPOSE: This study was to develop a convolutional neural network (CNN) model with a residual learning framework to predict the full-time 18F-florbetaben (18F-FBB) PET/CT images from corresponding short-time scans. METHODS: In this retrospective study, we enrolled 22 cognitively normal subjects, 20 patients with mild cognitive impairment, and 42 patients with Alzheimer disease. Twenty minutes of list-mode PET/CT data were acquired and reconstructed as the ground-truth images. The short-time scans were made in either 1, 2, 3, 4, or 5 minutes. The CNN with a residual learning framework was implemented to predict the ground-truth images of 18F-FBB PET/CT using short-time scans with either a single-slice or a 3-slice input layer. Model performance was evaluated by quantitative and qualitative analyses. Additionally, we quantified the amyloid load in the ground-truth and predicted images using the SUV ratio. RESULTS: On quantitative analyses, with increasing scan time, the normalized root-mean-squared error and the SUV ratio differences between predicted and ground-truth images gradually decreased, and the peak signal-to-noise ratio increased. On qualitative analysis, the predicted images from the 3-slice CNN model showed better image quality than those from the single-slice model. The 3-slice CNN model with a short-time scan of at least 2 minutes achieved comparable, quantitative prediction of full-time 18F-FBB PET/CT images, with adequate to excellent image quality. CONCLUSIONS: The 3-slice CNN model with a residual learning framework is promising for the prediction of full-time 18F-FBB PET/CT images from short-time scans.


Assuntos
Aprendizado Profundo , Processamento de Imagem Assistida por Computador/métodos , Tomografia Computadorizada com Tomografia por Emissão de Pósitrons , Amiloide/metabolismo , Compostos de Anilina , Encéfalo/diagnóstico por imagem , Encéfalo/metabolismo , Estudos de Viabilidade , Feminino , Humanos , Estudos Retrospectivos , Razão Sinal-Ruído , Estilbenos
20.
Nat Commun ; 12(1): 183, 2021 01 08.
Artigo em Inglês | MEDLINE | ID: mdl-33420039

RESUMO

We have reported that autophagy is crucial for clearance of amyloidogenic human IAPP (hIAPP) oligomer, suggesting that an autophagy enhancer could be a therapeutic modality against human diabetes with amyloid accumulation. Here, we show that a recently identified autophagy enhancer (MSL-7) reduces hIAPP oligomer accumulation in human induced pluripotent stem cell-derived ß-cells (hiPSC-ß-cells) and diminishes oligomer-mediated apoptosis of ß-cells. Protective effects of MSL-7 against hIAPP oligomer accumulation and hIAPP oligomer-mediated ß-cell death are significantly reduced in cells with knockout of MiTF/TFE family members such as Tfeb or Tfe3. MSL-7 improves glucose tolerance and ß-cell function of hIAPP+ mice on high-fat diet, accompanied by reduced hIAPP oligomer/amyloid accumulation and ß-cell apoptosis. Protective effects of MSL-7 against hIAPP oligomer-mediated ß-cell death and the development of diabetes are also significantly reduced by ß-cell-specific knockout of Tfeb. These results suggest that an autophagy enhancer could have therapeutic potential against human diabetes characterized by islet amyloid accumulation.


Assuntos
Amiloide/metabolismo , Proteínas Amiloidogênicas/metabolismo , Autofagia/fisiologia , Diabetes Mellitus Tipo 2/metabolismo , Polipeptídeo Amiloide das Ilhotas Pancreáticas/genética , Polipeptídeo Amiloide das Ilhotas Pancreáticas/metabolismo , Animais , Apoptose/fisiologia , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/genética , Técnicas de Inativação de Genes , Humanos , Células-Tronco Pluripotentes Induzidas/metabolismo , Células Secretoras de Insulina , Macroautofagia/fisiologia , Camundongos , Camundongos Transgênicos
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