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1.
PLoS One ; 15(7): e0233583, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32735619

RESUMO

Mutations that cause Huntington's Disease involve a polyglutamine (polyQ) sequence expansion beyond 35 repeats in exon 1 of Huntingtin. Intracellular inclusion bodies of mutant Huntingtin protein are a key feature of Huntington's disease brain pathology. We previously showed that in cell culture the formation of inclusions involved the assembly of disordered structures of mHtt exon 1 fragments (Httex1) and they were enriched with translational machinery when first formed. We hypothesized that nascent mutant Httex1 chains co-aggregate during translation by phase separation into liquid-like disordered aggregates and then convert to more rigid, amyloid structures. Here we further examined the mechanisms of inclusion assembly in a human epithelial kidney (AD293) cell culture model. We found mHttex1 did not appear to stall translation of its own nascent chain, or at best was marginal. We also found the inclusions appeared to recruit low levels of RNA but there was no difference in enrichment between early formed and mature inclusions. Proteins involved in translation or ribosome quality control were co-recruited to the inclusions (Ltn1 Rack1) compared to a protein not anticipated to be involved (NACAD), but there was no major specificity of enrichment in the early formed inclusions compared to mature inclusions. Furthermore, we observed co-aggregation with other proteins previously identified in inclusions, including Upf1 and chaperone-like proteins Sgta and Hspb1, which also suppressed aggregation at high co-expression levels. The newly formed inclusions also contained immobile mHttex1 molecules which points to the disordered aggregates being mechanically rigid prior to amyloid formation. Collectively our findings show little evidence that inclusion assembly arises by a discrete clustering of stalled nascent chains and associated quality control machinery. Instead, the machinery appear to be recruited continuously, or secondarily, to the nucleation of inclusion formation.


Assuntos
Éxons/genética , Proteína Huntingtina/genética , Elongação Traducional da Cadeia Peptídica , Agregados Proteicos/genética , RNA Mensageiro/genética , Ribossomos/metabolismo , Sequência de Bases , Células Epiteliais , Genes Reporter , Células HEK293 , Humanos , Proteína Huntingtina/biossíntese , Corpos de Inclusão/genética , Corpos de Inclusão/metabolismo , Repetições Minissatélites , Peptídeos , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo
2.
Nat Commun ; 11(1): 4052, 2020 08 13.
Artigo em Inglês | MEDLINE | ID: mdl-32792510

RESUMO

Turn-on fluorescence imaging is routinely studied; however, turn-on chemiluminescence has been rarely explored for in vivo imaging. Herein, we report the design and validation of chemiluminescence probe ADLumin-1 as a turn-on probe for amyloid beta (Aß) species. Two-photon imaging indicates that ADLumin-1 can efficiently cross the blood-brain barrier and provides excellent contrast for Aß plaques and cerebral amyloid angiopathy. In vivo brain imaging shows that the chemiluminescence signal of ADLumin-1 from 5-month-old transgenic 5xFAD mice is 1.80-fold higher than that from the age-matched wild-type mice. Moreover, we demonstrate that it is feasible to further dually-amplify signal via chemiluminescence resonance energy transfer (DAS-CRET) using two non-conjugated smart probes (ADLumin-1 and CRANAD-3) in solutions, brain homogenates, and in vivo whole brain imaging. Our results show that DAS-CRET can provide a 2.25-fold margin between 5-month-old 5xFAD mice and wild type mice. We believe that our strategy could be extended to other aggregating-prone proteins.


Assuntos
Peptídeos beta-Amiloides/química , Luminescência , Animais , Medições Luminescentes/métodos , Camundongos , Imagem Molecular/métodos , Imagem Óptica/métodos , Agregados Proteicos
3.
PLoS One ; 15(8): e0237328, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32790707

RESUMO

α-Synuclein (αSyn) fibrils spread from one neuronal cell to another. This prion-like phenomenon is believed to contribute to the progression of the pathology in Parkinson's disease and other synucleinopathies. The binding of αSyn fibrils originating from affected cells to the plasma membrane of naïve cells is key in their prion-like propagation propensity. To interfere with this process, we designed polypeptides derived from proteins we previously showed to interact with αSyn fibrils, namely the molecular chaperone Hsc70 and the sodium/potassium pump NaK-ATPase and assessed their capacity to bind αSyn fibrils and/or interfere with their take-up by cells of neuronal origin. We demonstrate here that polypeptides that coat αSyn fibrils surfaces in such a way that they are changed affect αSyn fibrils binding to the plasma membrane components and/or their take-up by cells. Altogether our observations suggest that the rationale design of αSyn fibrils polypeptide binders that interfere with their propagation between neuronal cells holds therapeutic potential.


Assuntos
Neurônios/efeitos dos fármacos , Peptídeos/farmacologia , Agregação Patológica de Proteínas/tratamento farmacológico , alfa-Sinucleína/metabolismo , Sequência de Aminoácidos , Amiloide/antagonistas & inibidores , Amiloide/metabolismo , Animais , Linhagem Celular , Proteínas de Choque Térmico HSC70/química , Proteínas de Choque Térmico HSC70/metabolismo , Proteínas de Choque Térmico HSC70/farmacologia , Humanos , Camundongos , Modelos Moleculares , Neurônios/metabolismo , Doença de Parkinson/tratamento farmacológico , Doença de Parkinson/metabolismo , Peptídeos/química , Príons/antagonistas & inibidores , Príons/metabolismo , Agregados Proteicos/efeitos dos fármacos , Agregação Patológica de Proteínas/metabolismo , ATPase Trocadora de Sódio-Potássio/química , ATPase Trocadora de Sódio-Potássio/metabolismo , ATPase Trocadora de Sódio-Potássio/farmacologia
4.
Nat Commun ; 11(1): 3914, 2020 08 06.
Artigo em Inglês | MEDLINE | ID: mdl-32764676

RESUMO

Cell polarity is fundamental to the development of both eukaryotes and prokaryotes, yet the mechanisms behind its formation are not well understood. Here we found that, phytohormone auxin-induced, sterol-dependent nanoclustering of cell surface transmembrane receptor kinase 1 (TMK1) is critical for the formation of polarized domains at the plasma membrane (PM) during the morphogenesis of cotyledon pavement cells (PC) in Arabidopsis. Auxin-induced TMK1 nanoclustering stabilizes flotillin1-associated ordered nanodomains, which in turn promote the nanoclustering of ROP6 GTPase that acts downstream of TMK1 to regulate cortical microtubule organization. In turn, cortical microtubules further stabilize TMK1- and flotillin1-containing nanoclusters at the PM. Hence, we propose a new paradigm for polarity formation: A diffusive signal triggers cell polarization by promoting cell surface receptor-mediated nanoclustering of signaling components and cytoskeleton-mediated positive feedback that reinforces these nanodomains into polarized domains.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/citologia , Arabidopsis/metabolismo , Polaridade Celular/fisiologia , Ácidos Indolacéticos/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Arabidopsis/genética , Proteínas de Arabidopsis/química , Membrana Celular/metabolismo , Polaridade Celular/genética , Metabolismo dos Lipídeos , Proteínas de Membrana/química , Proteínas de Membrana/metabolismo , Modelos Biológicos , Proteínas Monoméricas de Ligação ao GTP/química , Proteínas Monoméricas de Ligação ao GTP/metabolismo , Mutação , Reguladores de Crescimento de Planta/metabolismo , Plantas Geneticamente Modificadas , Agregados Proteicos , Estabilidade Proteica , Proteínas Serina-Treonina Quinases/química , Transdução de Sinais
5.
Nat Commun ; 11(1): 4305, 2020 08 27.
Artigo em Inglês | MEDLINE | ID: mdl-32855391

RESUMO

Oligomeric assemblies of tau and the RNA-binding proteins (RBPs) Musashi (MSI) are reported in Alzheimer's disease (AD). However, the role of MSI and tau interaction in their aggregation process and its effects are nor clearly known in neurodegenerative diseases. Here, we investigated the expression and cellular localization of MSI1 and MSI2 in the brains tissues of Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) as well as in the wild-type mice and tau knock-out and P301L tau mouse models. We observed that formation of pathologically relevant protein inclusions was driven by the aberrant interactions between MSI and tau in the nuclei associated with age-dependent extracellular depositions of tau/MSI complexes. Furthermore, tau and MSI interactions induced impairment of nuclear/cytoplasm transport, chromatin remodeling and nuclear lamina formation. Our findings provide mechanistic insight for pathological accumulation of MSI/tau aggregates providing a potential basis for therapeutic interventions in neurodegenerative proteinopathies.


Assuntos
Núcleo Celular/patologia , Proteínas do Tecido Nervoso/metabolismo , Doenças Neurodegenerativas/patologia , Proteínas de Ligação a RNA/metabolismo , Proteínas tau/metabolismo , Transporte Ativo do Núcleo Celular , Idoso , Idoso de 80 Anos ou mais , Animais , Núcleo Celular/metabolismo , Montagem e Desmontagem da Cromatina , Citoplasma/metabolismo , Modelos Animais de Doenças , Feminino , Lobo Frontal/citologia , Lobo Frontal/patologia , Células HEK293 , Humanos , Corpos de Inclusão/patologia , Masculino , Camundongos , Camundongos Transgênicos , Pessoa de Meia-Idade , Agregados Proteicos , Ligação Proteica , Proteínas tau/genética
6.
PLoS Biol ; 18(8): e3000851, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32822389

RESUMO

High levels of the amyloid-beta (Aß) peptide have been shown to disrupt neuronal function and induce hyperexcitability, but it is unclear what effects Aß-associated hyperexcitability may have on tauopathy pathogenesis or propagation in vivo. Using a novel transgenic mouse line to model the impact of human APP (hAPP)/Aß accumulation on tauopathy in the entorhinal cortex-hippocampal (EC-HIPP) network, we demonstrate that hAPP overexpression aggravates EC-Tau aggregation and accelerates pathological tau spread into the hippocampus. In vivo recordings revealed a strong role for hAPP/Aß, but not tau, in the emergence of EC neuronal hyperactivity and impaired theta rhythmicity. Chronic chemogenetic attenuation of EC neuronal hyperactivity led to reduced hAPP/Aß accumulation and reduced pathological tau spread into downstream hippocampus. These data strongly support the hypothesis that in Alzheimer's disease (AD), Aß-associated hyperactivity accelerates the progression of pathological tau along vulnerable neuronal circuits, and demonstrates the utility of chronic, neuromodulatory approaches in ameliorating AD pathology in vivo.


Assuntos
Doença de Alzheimer/genética , Precursor de Proteína beta-Amiloide/genética , Córtex Entorrinal/metabolismo , Tauopatias/genética , Proteínas tau/genética , Potenciais de Ação/fisiologia , Doença de Alzheimer/metabolismo , Doença de Alzheimer/patologia , Doença de Alzheimer/terapia , Precursor de Proteína beta-Amiloide/metabolismo , Animais , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/genética , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/metabolismo , Dependovirus/genética , Dependovirus/metabolismo , Modelos Animais de Doenças , Eletrodos Implantados , Córtex Entorrinal/patologia , Feminino , Regulação da Expressão Gênica , Vetores Genéticos/química , Vetores Genéticos/metabolismo , Hipocampo/metabolismo , Hipocampo/patologia , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Neurônios/metabolismo , Neurônios/patologia , Agregados Proteicos , Técnicas Estereotáxicas , Tauopatias/metabolismo , Tauopatias/patologia , Tauopatias/terapia , Ritmo Teta/fisiologia , Transdução Genética , Transgenes , Proteínas tau/metabolismo
7.
PLoS Biol ; 18(7): e3000564, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32701952

RESUMO

Amyloids are protein aggregates with a highly ordered spatial structure giving them unique physicochemical properties. Different amyloids not only participate in the development of numerous incurable diseases but control vital functions in archaea, bacteria and eukarya. Plants are a poorly studied systematic group in the field of amyloid biology. Amyloid properties have not yet been demonstrated for plant proteins under native conditions in vivo. Here we show that seeds of garden pea Pisum sativum L. contain amyloid-like aggregates of storage proteins, the most abundant one, 7S globulin Vicilin, forms bona fide amyloids in vivo and in vitro. Full-length Vicilin contains 2 evolutionary conserved ß-barrel domains, Cupin-1.1 and Cupin-1.2, that self-assemble in vitro into amyloid fibrils with similar physicochemical properties. However, Cupin-1.2 fibrils unlike Cupin-1.1 can seed Vicilin fibrillation. In vivo, Vicilin forms amyloids in the cotyledon cells that bind amyloid-specific dyes and possess resistance to detergents and proteases. The Vicilin amyloid accumulation increases during seed maturation and wanes at germination. Amyloids of Vicilin resist digestion by gastrointestinal enzymes, persist in canned peas, and exhibit toxicity for yeast and mammalian cells. Our finding for the first time reveals involvement of amyloid formation in the accumulation of storage proteins in plant seeds.


Assuntos
Amiloide/metabolismo , Ervilhas/metabolismo , Proteínas de Armazenamento de Sementes/metabolismo , Sementes/metabolismo , Amiloide/ultraestrutura , Detergentes/farmacologia , Escherichia coli/metabolismo , Íons , Pancreatina/metabolismo , Ervilhas/efeitos dos fármacos , Pepsina A/metabolismo , Agregados Proteicos , Domínios Proteicos , Proteínas Recombinantes/química , Proteínas Recombinantes/farmacologia , Saccharomyces cerevisiae/metabolismo , Proteínas de Armazenamento de Sementes/química , Proteínas de Armazenamento de Sementes/farmacologia , Proteínas de Armazenamento de Sementes/ultraestrutura
8.
Nature ; 584(7821): 410-414, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32641833

RESUMO

In metazoans, the secreted proteome participates in intercellular signalling and innate immunity, and builds the extracellular matrix scaffold around cells. Compared with the relatively constant intracellular environment, conditions for proteins in the extracellular space are harsher, and low concentrations of ATP prevent the activity of intracellular components of the protein quality-control machinery. Until now, only a few bona fide extracellular chaperones and proteases have been shown to limit the aggregation of extracellular proteins1-5. Here we performed a systematic analysis of the extracellular proteostasis network in Caenorhabditis elegans with an RNA interference screen that targets genes that encode the secreted proteome. We discovered 57 regulators of extracellular protein aggregation, including several proteins related to innate immunity. Because intracellular proteostasis is upregulated in response to pathogens6-9, we investigated whether pathogens also stimulate extracellular proteostasis. Using a pore-forming toxin to mimic a pathogenic attack, we found that C. elegans responded by increasing the expression of components of extracellular proteostasis and by limiting aggregation of extracellular proteins. The activation of extracellular proteostasis was dependent on stress-activated MAP kinase signalling. Notably, the overexpression of components of extracellular proteostasis delayed ageing and rendered worms resistant to intoxication. We propose that enhanced extracellular proteostasis contributes to systemic host defence by maintaining a functional secreted proteome and avoiding proteotoxicity.


Assuntos
Caenorhabditis elegans/metabolismo , Caenorhabditis elegans/microbiologia , Espaço Extracelular/metabolismo , Agregados Proteicos , Proteostase , Envelhecimento/metabolismo , Animais , Caenorhabditis elegans/citologia , Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/metabolismo , Sistema de Sinalização das MAP Quinases , Agregação Patológica de Proteínas/prevenção & controle , Proteoma/genética , Proteoma/metabolismo , Interferência de RNA
9.
Food Chem ; 332: 127396, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32615386

RESUMO

The effects of oxidation degree on the isoelectric point (pI), aggregation, and structural characteristics for pork myofibrillar protein (MP) were studied by employing extracted MP, which was incubated by using a hydroxyl radical oxidation system. The concentrations of hydrogen peroxide (H2O2) were 0, 0.5, 1, 3, 5, 10, and 20 mM. With the increased oxidation degree, the contents of α-helix, ionic bonds, and hydrogen bonds decreased significantly (P < 0.05). Moreover, the pI value and total amino acids showed a declining trend, and the ß-sheet as well as solubility rised firstly and then declined. On the contrary, random curl, ß-turn, and turbidity increased significantly (P < 0.05). Therefore, amino acid side chain groups were modified, and the opposite effect, caused by oxidation that leads to protein cross-linking and aggregation, was greater than the promotion effect, such as net negative charge, these are the main factors that leads to the instability of protein solution systems.


Assuntos
Proteínas Musculares/química , Agregados Proteicos , Animais , Peróxido de Hidrogênio/química , Radical Hidroxila/química , Ponto Isoelétrico , Oxirredução , Solubilidade , Suínos
10.
Arterioscler Thromb Vasc Biol ; 40(9): 2310-2321, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32611242

RESUMO

OBJECTIVE: Plant stanol ester supplementation (2-3 g plant stanols/d) reduces plasma LDL (low-density lipoprotein) cholesterol concentration by 9% to 12% and is, therefore, recommended as part of prevention and treatment of atherosclerotic cardiovascular disease. In addition to plasma LDL-cholesterol concentration, also qualitative properties of LDL particles can influence atherogenesis. However, the effect of plant stanol ester consumption on the proatherogenic properties of LDL has not been studied. Approach and Results: Study subjects (n=90) were randomized to consume either a plant stanol ester-enriched spread (3.0 g plant stanols/d) or the same spread without added plant stanol esters for 6 months. Blood samples were taken at baseline and after the intervention. The aggregation susceptibility of LDL particles was analyzed by inducing aggregation of isolated LDL and following aggregate formation. LDL lipidome was determined by mass spectrometry. Binding of serum lipoproteins to proteoglycans was measured using a microtiter well-based assay. LDL aggregation susceptibility was decreased in the plant stanol ester group, and the median aggregate size after incubation for 2 hours decreased from 1490 to 620 nm, P=0.001. Plant stanol ester-induced decrease in LDL aggregation was more extensive in participants having body mass index<25 kg/m2. Decreased LDL aggregation susceptibility was associated with decreased proportion of LDL-sphingomyelins and increased proportion of LDL-triacylglycerols. LDL binding to proteoglycans was decreased in the plant stanol ester group, the decrease depending on decreased serum LDL-cholesterol concentration. CONCLUSIONS: Consumption of plant stanol esters decreases the aggregation susceptibility of LDL particles by modifying LDL lipidome. The resulting improvement of LDL quality may be beneficial for cardiovascular health. Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT01315964.


Assuntos
Dieta , Ésteres/administração & dosagem , Hipercolesterolemia/dietoterapia , Lipoproteínas LDL/sangue , Fitosteróis/administração & dosagem , Agregados Proteicos , Adulto , Idoso , Biomarcadores/sangue , LDL-Colesterol/sangue , Método Duplo-Cego , Feminino , Finlândia , Humanos , Hipercolesterolemia/sangue , Hipercolesterolemia/diagnóstico , Lipidômica , Masculino , Pessoa de Meia-Idade , Proteoglicanas/sangue , Esfingomielinas/sangue , Fatores de Tempo , Resultado do Tratamento , Triglicerídeos/sangue , Adulto Jovem
11.
Nat Commun ; 11(1): 2820, 2020 06 04.
Artigo em Inglês | MEDLINE | ID: mdl-32499486

RESUMO

As an intrinsically disordered protein, monomeric alpha-synuclein (aSyn) occupies a large conformational space. Certain conformations lead to aggregation prone and non-aggregation prone intermediates, but identifying these within the dynamic ensemble of monomeric conformations is difficult. Herein, we used the biologically relevant calcium ion to investigate the conformation of monomeric aSyn in relation to its aggregation propensity. We observe that the more exposed the N-terminus and the beginning of the NAC region of aSyn are, the more aggregation prone monomeric aSyn conformations become. Solvent exposure of the N-terminus of aSyn occurs upon release of C-terminus interactions when calcium binds, but the level of exposure and aSyn's aggregation propensity is sequence and post translational modification dependent. Identifying aggregation prone conformations of monomeric aSyn and the environmental conditions they form under will allow us to design new therapeutics targeted to the monomeric protein.


Assuntos
Agregados Proteicos , alfa-Sinucleína/química , alfa-Sinucleína/metabolismo , Benzotiazóis/metabolismo , Cálcio/metabolismo , Humanos , Cinética , Proteínas Mutantes/química , Proteínas Mutantes/metabolismo , Mutação/genética , Fosforilação , Conformação Proteica , Espectroscopia de Prótons por Ressonância Magnética , Relação Estrutura-Atividade
12.
Nat Commun ; 11(1): 3106, 2020 06 19.
Artigo em Inglês | MEDLINE | ID: mdl-32561765

RESUMO

Nonsense-mediated mRNA decay (NMD) typifies an mRNA surveillance pathway. Because NMD necessitates a translation event to recognize a premature termination codon on mRNAs, truncated misfolded polypeptides (NMD-polypeptides) could potentially be generated from NMD substrates as byproducts. Here, we show that when the ubiquitin-proteasome system is overwhelmed, various misfolded polypeptides including NMD-polypeptides accumulate in the aggresome: a perinuclear nonmembranous compartment eventually cleared by autophagy. Hyperphosphorylation of the key NMD factor UPF1 is required for selective targeting of the misfolded polypeptide aggregates toward the aggresome via the CTIF-eEF1A1-DCTN1 complex: the aggresome-targeting cellular machinery. Visualization at a single-particle level reveals that UPF1 increases the frequency and fidelity of movement of CTIF aggregates toward the aggresome. Furthermore, the apoptosis induced by proteotoxic stresses is suppressed by UPF1 hyperphosphorylation. Altogether, our data provide evidence that UPF1 functions in the regulation of a protein surveillance as well as an mRNA quality control.


Assuntos
Degradação do RNAm Mediada por Códon sem Sentido , Complexo de Endopeptidases do Proteassoma/metabolismo , RNA Helicases/metabolismo , RNA Mensageiro/metabolismo , Transativadores/metabolismo , Resposta a Proteínas não Dobradas/genética , Autofagia , Códon sem Sentido , Complexo Dinactina/metabolismo , Fatores de Iniciação em Eucariotos/metabolismo , Células HEK293 , Células HeLa , Humanos , Imagem Molecular , Fator 1 de Elongação de Peptídeos/metabolismo , Fosforilação , Agregados Proteicos/genética , Imagem Individual de Molécula , Ubiquitina/metabolismo
13.
PLoS One ; 15(6): e0234502, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32525915

RESUMO

Preservation of blood plasma in the dried state would facilitate long-term storage and transport at ambient temperatures, without the need of to use liquid nitrogen tanks or freezers. The aim of this study was to investigate the feasibility of dry preservation of human plasma, using sugars as lyoprotectants, and evaluate macromolecular stability of plasma components during storage. Blood plasma from healthy donors was freeze dried using 0-10% glucose, sucrose, or trehalose, and stored at various temperatures. Differential scanning calorimetry was used to measure the glass transition temperatures of freeze-dried samples. Protein aggregation, the overall protein secondary structure, and oxidative damage were studied under different storage conditions. Differential scanning calorimetry measurements showed that plasma freeze-dried with glucose, sucrose and trehalose have glass transition temperatures of respectively 72±3.4°C, 46±11°C, 15±2.4°C. It was found that sugars diminish freeze-drying induced protein aggregation in a dose-dependent manner, and that a 10% (w/v) sugar concentration almost entirely prevents protein aggregation. Protein aggregation after rehydration coincided with relatively high contents of ß-sheet structures in the dried state. Trehalose reduced the rate of protein aggregation during storage at elevated temperatures, and plasma that is freeze- dried plasma with trehalose showed a reduced accumulation of reactive oxygen species and protein oxidation products during storage. In conclusion, freeze-drying plasma with trehalose provides an attractive alternative to traditional cryogenic preservation.


Assuntos
Proteínas Sanguíneas/metabolismo , Plasma/química , Preservação Biológica/métodos , Conservantes Farmacêuticos/química , Trealose/química , Proteínas Sanguíneas/química , Estabilidade de Medicamentos , Armazenamento de Medicamentos , Liofilização , Humanos , Agregados Proteicos , Conformação Proteica em Folha beta , Estabilidade Proteica , Temperatura de Transição , Vitrificação
14.
Biotechnol Adv ; 42: 107573, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32512220

RESUMO

In the biological milieu of a cell, soluble crowding molecules and rigid confined environments strongly influence whether the protein is properly folded, intrinsically disordered proteins assemble into distinct phases, or a denatured or aggregated protein species is favored. Such crowding and confinement factors act to exclude solvent volume from the protein molecules, resulting in an increased local protein concentration and decreased protein entropy. A protein's structure is inherently tied to its function. Examples of processes where crowding and confinement may strongly influence protein function include transmembrane protein dimerization, enzymatic activity, assembly of supramolecular structures (e.g., microtubules), nuclear condensates containing transcriptional machinery, protein aggregation in the contexts of disease and protein therapeutics. Historically, most protein structures have been determined from pure, dilute protein solutions or pure crystals. However, these are not the environments in which these proteins function. Thus, there has been an increased emphasis on analyzing protein structure and dynamics in more "in vivo-like" environments. Complex in vitro models using hydrogel scaffolds to study proteins may better mimic features of the in vivo environment. Therefore, analytical techniques need to be optimized for real-time analysis of proteins within hydrogel scaffolds.


Assuntos
Hidrogéis , Agregados Proteicos , Dobramento de Proteína , Proteínas
15.
Nat Commun ; 11(1): 2993, 2020 06 12.
Artigo em Inglês | MEDLINE | ID: mdl-32532970

RESUMO

The accumulation of protein aggregates is involved in the onset of many neurodegenerative diseases. Aggrephagy is a selective type of autophagy that counteracts neurodegeneration by degrading such aggregates. In this study, we found that LC3C cooperates with lysosomal TECPR1 to promote the degradation of disease-related protein aggregates in neural stem cells. The N-terminal WD-repeat domain of TECPR1 selectively binds LC3C which decorates matured autophagosomes. The interaction of LC3C and TECPR1 promotes the recruitment of autophagosomes to lysosomes for degradation. Augmented expression of TECPR1 in neural stem cells reduces the number of protein aggregates by promoting their autophagic clearance, whereas knockdown of LC3C inhibits aggrephagy. The PH domain of TECPR1 selectively interacts with PtdIns(4)P to target TECPR1 to PtdIns(4)P containing lysosomes. Exchanging the PH against a tandem-FYVE domain targets TECPR1 ectopically to endosomes. This leads to an accumulation of LC3C autophagosomes at endosomes and prevents their delivery to lysosomes.


Assuntos
Autofagossomos/metabolismo , Lisossomos/metabolismo , Proteínas de Membrana/metabolismo , Proteínas Associadas aos Microtúbulos/metabolismo , Células-Tronco Neurais/metabolismo , Autofagossomos/ultraestrutura , Autofagia/genética , Sistemas CRISPR-Cas/genética , Linhagem Celular , Endossomos/metabolismo , Células HeLa , Humanos , Lisossomos/ultraestrutura , Proteínas de Membrana/química , Proteínas de Membrana/genética , Microscopia Confocal , Microscopia Imunoeletrônica , Proteínas Associadas aos Microtúbulos/química , Proteínas Associadas aos Microtúbulos/genética , Células-Tronco Neurais/citologia , Doenças Neurodegenerativas/metabolismo , Agregados Proteicos , Agregação Patológica de Proteínas , Ligação Proteica , Transporte Proteico , Proteólise , Interferência de RNA
16.
Proc Natl Acad Sci U S A ; 117(24): 13509-13518, 2020 06 16.
Artigo em Inglês | MEDLINE | ID: mdl-32493749

RESUMO

Protein misfolding and aggregation is the hallmark of numerous human disorders, including Alzheimer's disease. This process involves the formation of transient and heterogeneous soluble oligomers, some of which are highly cytotoxic. A major challenge for the development of effective diagnostic and therapeutic tools is thus the detection and quantification of these elusive oligomers. Here, to address this problem, we develop a two-step rational design method for the discovery of oligomer-specific antibodies. The first step consists of an "antigen scanning" phase in which an initial panel of antibodies is designed to bind different epitopes covering the entire sequence of a target protein. This procedure enables the determination through in vitro assays of the regions exposed in the oligomers but not in the fibrillar deposits. The second step involves an "epitope mining" phase, in which a second panel of antibodies is designed to specifically target the regions identified during the scanning step. We illustrate this method in the case of the amyloid ß (Aß) peptide, whose oligomers are associated with Alzheimer's disease. Our results show that this approach enables the accurate detection and quantification of Aß oligomers in vitro, and in Caenorhabditis elegans and mouse hippocampal tissues.


Assuntos
Peptídeos beta-Amiloides/metabolismo , Anticorpos/imunologia , Agregados Proteicos , Doença de Alzheimer/diagnóstico , Doença de Alzheimer/metabolismo , Peptídeos beta-Amiloides/química , Animais , Anticorpos/química , Anticorpos/metabolismo , Especificidade de Anticorpos , Caenorhabditis elegans , Modelos Animais de Doenças , Epitopos , Hipocampo/metabolismo , Camundongos , Ligação Proteica , Conformação Proteica , Anticorpos de Domínio Único
17.
Food Chem ; 331: 127322, 2020 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-32569968

RESUMO

Here we report a novel strategy for the immobilization of invertase using amyloid-like fibrils as a support. Optimal conditions to get Tyr-Tyr covalent binding between invertase and the support were determined using a photocrosslinking approach. The biological fibrils with invertase activity turn into microstructured catalysts according to electron microscopy outcomes. Thermal and storage stability as well as optimal pH and temperature of the enzyme were conserved. Moreover, the immobilized enzyme recovered by low g-force centrifugation retained 83% of its initial enzymatic activity after 15 reuse cycles. Considering that enzyme cost is the most significant part of the overall fee of enzymatic biomass conversion, the highly efficient recovery/reuse strategy described herein becomes relevant. Besides, it can also be applied to the immobilization of other enzymes for industrial biocatalysis.


Assuntos
Biocatálise , Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo , beta-Frutofuranosidase/química , beta-Frutofuranosidase/metabolismo , Estabilidade Enzimática , Concentração de Íons de Hidrogênio , Agregados Proteicos , Temperatura
18.
J Vis Exp ; (159)2020 05 22.
Artigo em Inglês | MEDLINE | ID: mdl-32510501

RESUMO

Protein interactions at cellular interfaces dictate a multitude of biological outcomes ranging from tissue development and cancer progression to synapse formation and maintenance. Many of these fundamental interactions occur in trans and are typically induced by heterophilic or homophilic interactions between cells expressing membrane anchored binding pairs. Elucidating how disease relevant mutations disrupt these fundamental protein interactions can provide insight into a myriad of cell biology fields. Many protein-protein interaction assays do not typically disambiguate between cis and trans interactions, which potentially leads to an overestimation of the extent of binding that is occurring in vivo and involve labor intensive purification of protein and/or specialized monitoring equipment. Here, we present an optimized simple protocol that allows for the observation and quantification of only trans interactions without the need for lengthy protein purifications or specialized equipment. The HEK cell aggregation assay involves the mixing of two independent populations of HEK cells, each expressing membrane-bound cognate ligands. After a short incubation period, samples are imaged and the resulting aggregates are quantified.


Assuntos
Comunicação Celular , Técnicas Citológicas/métodos , Agregados Proteicos , Agregação Celular , Células HEK293 , Humanos , Ligantes
19.
Food Chem ; 329: 127183, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-32521427

RESUMO

Combined effects of pH and thermal treatments on black kidney bean lectin (BKBL) were investigated by response surface methodology (RSM). Low-pH (1.0, 2.0, 3.0) incubation decreased hemagglutination activity (HA) and IgE-binding capacity, but the activities would be restored when the lectin was treated by pH shifting to 7.2. Conformational structure analyses indicated that low-pH induced protein unfolding and pH-shifting treatment resulted in a limited structural rearrangement. Mild heating, such as 60 °C for 3 min, slightly increased the HA and IgE-binding activities of pH shifted BKBL, but no obvious effects in the pH 1.0 incubated BKBL. High-temperature and long-time treatment might induce the protein aggregation, further decreased HA and IgE-binding capacities. RSM results showed both IgE-binding capacity and HA were the lowest under the combination of pH 1.0 incubation with 80 °C heating for 15 min or pH shifting from 1.0 to 7.2 with 100 °C heating for 10 min.


Assuntos
Imunoglobulina E/metabolismo , Lectinas/química , Phaseolus/metabolismo , Dicroísmo Circular , Temperatura Alta , Concentração de Íons de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Lectinas/metabolismo , Agregados Proteicos , Conformação Proteica em alfa-Hélice , Estrutura Terciária de Proteína , Espectrometria de Fluorescência
20.
Food Chem ; 330: 127319, 2020 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-32569936

RESUMO

The influence of fresh egg white (EW) addition on the quality characteristics and protein aggregation in oat noodles containing wheat flour and gluten was studied. EW addition decreased cooking loss and increased cooking time of 70% oat noodles. The hardness, chewiness, tensile force and tensile distance improved significantly. A smooth surface and continuous protein network were observed by scanning electron microscopy (SEM) after adding EW. After cooking, the peak area in SE-HPLC profile of 70% oat noodles with EW decreased obviously. The extractabilities of protein in sodium dodecyl sulfate containing medium (SDSEP) of cooked wheat and oat noodles under non-reducing condition were lower than those of samples under reducing condition. The protein bands changes in SDS-PAGE profiles showed that EW could induce disulfide cross-linking of proteins in noodles. EW addition promoted proteins interaction and improved the cooking and texture properties of oat noodles.


Assuntos
Avena , Clara de Ovo/química , Farinha , Qualidade dos Alimentos , Cromatografia em Gel , Cromatografia Líquida de Alta Pressão , Culinária , Dissulfetos/química , Eletroforese em Gel de Poliacrilamida , Farinha/análise , Indústria de Processamento de Alimentos , Glutens , Dureza , Microscopia Eletrônica de Varredura , Agregados Proteicos , Triticum
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