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1.
Nat Struct Mol Biol ; 27(2): 192-201, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-32042150

RESUMO

Point mutations in cysteine string protein-α (CSPα) cause dominantly inherited adult-onset neuronal ceroid lipofuscinosis (ANCL), a rapidly progressing and lethal neurodegenerative disease with no treatment. ANCL mutations are proposed to trigger CSPα aggregation/oligomerization, but the mechanism of oligomer formation remains unclear. Here we use purified proteins, mouse primary neurons and patient-derived induced neurons to show that the normally palmitoylated cysteine string region of CSPα loses palmitoylation in ANCL mutants. This allows oligomerization of mutant CSPα via ectopic binding of iron-sulfur (Fe-S) clusters. The resulting oligomerization of mutant CSPα causes its mislocalization and consequent loss of its synaptic SNARE-chaperoning function. We then find that pharmacological iron chelation mitigates the oligomerization of mutant CSPα, accompanied by partial rescue of the downstream SNARE defects and the pathological hallmark of lipofuscin accumulation. Thus, the iron chelators deferiprone (L1) and deferoxamine (Dfx), which are already used to treat iron overload in humans, offer a new approach for treating ANCL.


Assuntos
Proteínas de Choque Térmico HSP40/genética , Proteínas de Membrana/genética , Lipofuscinoses Ceroides Neuronais/genética , Mutação Puntual , Agregação Patológica de Proteínas/genética , Animais , Células Cultivadas , Feminino , Células HEK293 , Proteínas de Choque Térmico HSP40/metabolismo , Humanos , Quelantes de Ferro/metabolismo , Lipoilação , Proteínas de Membrana/metabolismo , Camundongos , Lipofuscinoses Ceroides Neuronais/metabolismo , Neurônios/metabolismo , Agregação Patológica de Proteínas/metabolismo , Ligação Proteica , Multimerização Proteica
2.
Nat Commun ; 11(1): 1004, 2020 02 21.
Artigo em Inglês | MEDLINE | ID: mdl-32081878

RESUMO

Cytoplasmic aggregation of TDP-43 characterizes degenerating neurons in most cases of amyotrophic lateral sclerosis (ALS). Here, we develop an optogenetic TDP-43 variant (opTDP-43), whose multimerization status can be modulated in vivo through external light illumination. Using the translucent zebrafish neuromuscular system, we demonstrate that short-term light stimulation reversibly induces cytoplasmic opTDP-43 mislocalization, but not aggregation, in the spinal motor neuron, leading to an axon outgrowth defect associated with myofiber denervation. In contrast, opTDP-43 forms pathological aggregates in the cytoplasm after longer-term illumination and seeds non-optogenetic TDP-43 aggregation. Furthermore, we find that an ALS-linked mutation in the intrinsically disordered region (IDR) exacerbates the light-dependent opTDP-43 toxicity on locomotor behavior. Together, our results propose that IDR-mediated TDP-43 oligomerization triggers both acute and long-term pathologies of motor neurons, which may be relevant to the pathogenesis and progression of ALS.


Assuntos
Esclerose Amiotrófica Lateral/metabolismo , Esclerose Amiotrófica Lateral/patologia , Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/metabolismo , Neurônios Motores/metabolismo , Neurônios Motores/patologia , Medula Espinal/metabolismo , Medula Espinal/patologia , Esclerose Amiotrófica Lateral/genética , Animais , Animais Geneticamente Modificados , Proteínas de Ligação a DNA/genética , Modelos Animais de Doenças , Humanos , Proteínas Intrinsicamente Desordenadas/química , Proteínas Intrinsicamente Desordenadas/genética , Proteínas Intrinsicamente Desordenadas/metabolismo , Modelos Moleculares , Mutação , Optogenética , Agregação Patológica de Proteínas/genética , Agregação Patológica de Proteínas/metabolismo , Multimerização Proteica , Estabilidade Proteica , Regulação para Cima , Peixe-Zebra
3.
PLoS One ; 15(1): e0227655, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31999698

RESUMO

Mutations in Cu/Zn superoxide dismutase 1 (SOD1) associated with familial amyotrophic lateral sclerosis cause the protein to aggregate via a prion-like process in which soluble molecules are recruited to aggregates by conformational templating. These misfolded SOD1 proteins can propagate aggregation-inducing conformations across cellular membranes. Prior studies demonstrated that mutation of a Trp (W) residue at position 32 to Ser (S) suppresses the propagation of misfolded conformations between cells, whereas other studies have shown that mutation of Trp 32 to Phe (F), or Cys 111 to Ser, can act in cis to attenuate aggregation of mutant SOD1. By expressing mutant SOD1 fused with yellow fluorescent protein (YFP), we compared the relative ability of these mutations to modulate the formation of inclusions by ALS-mutant SOD1 (G93A and G85R). Only mutation of Trp 32 to Ser persistently reduced the formation of the amorphous inclusions that form in these cells, consistent with the idea that a Ser at position 32 inhibits templated propagation of aggregation prone conformations. To further test this idea, we produced aggregated fibrils of recombinant SOD1-W32S in vitro and injected them into the spinal cords of newborn mice expressing G85R-SOD1: YFP. The injected mice developed an earlier onset paralysis with a frequency similar to mice injected with WT SOD1 fibrils, generating a strain of misfolded SOD1 that produced highly fibrillar inclusion pathology. These findings suggest that the effect of Trp 32 in modulating the propagation of misfolded SOD1 conformations may be dependent upon the "strain" of the conformer that is propagating.


Assuntos
Príons/química , Príons/genética , Superóxido Dismutase-1/química , Superóxido Dismutase-1/genética , Substituição de Aminoácidos , Esclerose Amiotrófica Lateral/genética , Esclerose Amiotrófica Lateral/metabolismo , Animais , Animais Recém-Nascidos , Modelos Animais de Doenças , Feminino , Humanos , Masculino , Camundongos , Camundongos Transgênicos , Mutagênese Sítio-Dirigida , Príons/metabolismo , Agregação Patológica de Proteínas/genética , Agregação Patológica de Proteínas/metabolismo , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Superóxido Dismutase-1/metabolismo , Triptofano/química
4.
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
5.
Nat Commun ; 11(1): 411, 2020 01 21.
Artigo em Inglês | MEDLINE | ID: mdl-31964863

RESUMO

Alzheimer's disease (AD) is characterized by amyloid plaques and progressive cerebral atrophy. Here, we report FAM222A as a putative brain atrophy susceptibility gene. Our cross-phenotype association analysis of imaging genetics indicates a potential link between FAM222A and AD-related regional brain atrophy. The protein encoded by FAM222A is predominantly expressed in the CNS and is increased in brains of patients with AD and in an AD mouse model. It accumulates within amyloid deposits, physically interacts with amyloid-ß (Aß) via its N-terminal Aß binding domain, and facilitates Aß aggregation. Intracerebroventricular infusion or forced expression of this protein exacerbates neuroinflammation and cognitive dysfunction in an AD mouse model whereas ablation of this protein suppresses the formation of amyloid deposits, neuroinflammation and cognitive deficits in the AD mouse model. Our data support the pathological relevance of protein encoded by FAM222A in AD.


Assuntos
Doença de Alzheimer/genética , Peptídeos beta-Amiloides/metabolismo , Disfunção Cognitiva/genética , Proteínas do Tecido Nervoso/genética , Placa Amiloide/genética , Agregação Patológica de Proteínas/genética , Idoso , Idoso de 80 Anos ou mais , Doença de Alzheimer/diagnóstico por imagem , Doença de Alzheimer/patologia , Animais , Atrofia/diagnóstico por imagem , Atrofia/genética , Atrofia/patologia , Encéfalo/diagnóstico por imagem , Encéfalo/patologia , Disfunção Cognitiva/patologia , Conjuntos de Dados como Assunto , Modelos Animais de Doenças , Feminino , Predisposição Genética para Doença , Estudo de Associação Genômica Ampla , Humanos , Masculino , Camundongos , Camundongos Transgênicos , Pessoa de Meia-Idade , Proteínas do Tecido Nervoso/metabolismo , Placa Amiloide/patologia , Polimorfismo de Nucleotídeo Único , Agregação Patológica de Proteínas/diagnóstico por imagem , Agregação Patológica de Proteínas/patologia
6.
Mol Biol (Mosk) ; 53(6): 1049-1056, 2019.
Artigo em Russo | MEDLINE | ID: mdl-31876283

RESUMO

Zinc ions and glycosaminoglycans (GAGs) are found in amyloid deposits and are known to modulate the ß-amyloid peptide (Aß) aggregation, which is thought to be a key event in the pathogenesis of Alzheimer's disease (AD). Correlation spectroscopy was used to study how the H6R and D7H mutations of the metal-binding domain (MBD) of Aß42 affect the modulation of its zinc-induced aggregation by the model GAG heparin. The H6R mutation was shown to decrease and the D7H mutation to increase the Aß42 propensity to aggregate in the presence of zinc ions. In addition, H6R diminished and D7H enhanced the modulating effect of heparin. The difference in the heparin-dependent modulation was associated with coordination of zinc ions within the MBDs of the mutant peptides. The findings indicate that anion-binding sites formed by complexes of zinc ions with the Aß MBD play an essential role in the interaction of zinc-induced Aß aggregates with heparin.


Assuntos
Peptídeos beta-Amiloides/efeitos dos fármacos , Peptídeos beta-Amiloides/genética , Heparina/farmacologia , Mutação , Fragmentos de Peptídeos/efeitos dos fármacos , Fragmentos de Peptídeos/genética , Agregação Patológica de Proteínas/genética , Zinco/farmacologia , Doença de Alzheimer/genética , Doença de Alzheimer/patologia , Peptídeos beta-Amiloides/química , Humanos , Fragmentos de Peptídeos/química
7.
Nat Struct Mol Biol ; 26(11): 1044-1052, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31695184

RESUMO

Deposits of amyloid fibrils of α-synuclein are the histological hallmarks of Parkinson's disease, dementia with Lewy bodies and multiple system atrophy, with hereditary mutations in α-synuclein linked to the first two of these conditions. Seeing the changes to the structures of amyloid fibrils bearing these mutations may help to understand these diseases. To this end, we determined the cryo-EM structures of α-synuclein fibrils containing the H50Q hereditary mutation. We find that the H50Q mutation results in two previously unobserved polymorphs of α-synuclein: narrow and wide fibrils, formed from either one or two protofilaments, respectively. These structures recapitulate conserved features of the wild-type fold but reveal new structural elements, including a previously unobserved hydrogen-bond network and surprising new protofilament arrangements. The structures of the H50Q polymorphs help to rationalize the faster aggregation kinetics, higher seeding capacity in biosensor cells and greater cytotoxicity that we observe for H50Q compared to wild-type α-synuclein.


Assuntos
Amiloide/genética , Mutação Puntual , Agregação Patológica de Proteínas/genética , alfa-Sinucleína/genética , Sequência de Aminoácidos , Amiloide/química , Amiloide/ultraestrutura , Microscopia Crioeletrônica , Células HEK293 , Humanos , Modelos Moleculares , Doença de Parkinson/genética , Conformação Proteica , alfa-Sinucleína/química , alfa-Sinucleína/ultraestrutura
8.
Nat Commun ; 10(1): 3134, 2019 07 17.
Artigo em Inglês | MEDLINE | ID: mdl-31316070

RESUMO

OPCML, a tumor suppressor gene, is frequently silenced epigenetically in ovarian and other cancers. Here we report, by analysis of databases of tumor sequences, the observation of OPCML somatic missense mutations from various tumor types and the impact of these mutations on OPCML function, by solving the X-ray crystal structure of this glycoprotein to 2.65 Å resolution. OPCML consists of an extended arrangement of three immunoglobulin-like domains and homodimerizes via a network of contacts between membrane-distal domains. We report the generation of a panel of OPCML variants with representative clinical mutations and demonstrate clear phenotypic effects in vitro and in vivo including changes to anchorage-independent growth, interaction with activated cognate receptor tyrosine kinases, cellular migration, invasion in vitro and tumor growth in vivo. Our results suggest that clinically occurring somatic missense mutations in OPCML have the potential to contribute to tumorigenesis in a variety of cancers.


Assuntos
Moléculas de Adesão Celular/genética , Epigênese Genética , Neoplasias Ovarianas/genética , Moléculas de Adesão Celular/química , Transformação Celular Neoplásica , Cristalografia por Raios X , Feminino , Proteínas Ligadas por GPI/química , Proteínas Ligadas por GPI/genética , Glicosilação , Humanos , Mutação de Sentido Incorreto , Invasividade Neoplásica , Agregação Patológica de Proteínas/genética , Estrutura Terciária de Proteína
9.
PLoS Comput Biol ; 15(7): e1007225, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31323035

RESUMO

Exposure to the environmental toxin ß-methylamino-L-alanine (BMAA) is linked to amyotrophic lateral sclerosis (ALS), but its disease-promoting mechanism remains unknown. We propose that incorporation of BMAA into the ALS-linked protein Cu,Zn superoxide dismutase (SOD1) upon translation promotes protein misfolding and aggregation, which has been linked to ALS onset and progression. Using molecular simulation and predictive energetic computation, we demonstrate that substituting any serine with BMAA in SOD1 results in structural destabilization and aberrant dynamics, promoting neurotoxic SOD1 aggregation. We propose that translational incorporation of BMAA into SOD1 is directly responsible for its toxicity in neurodegeneration, and BMAA modification of SOD1 may serve as a biomarker of ALS.


Assuntos
Diamino Aminoácidos/farmacocinética , Diamino Aminoácidos/toxicidade , Esclerose Amiotrófica Lateral/etiologia , Esclerose Amiotrófica Lateral/metabolismo , Superóxido Dismutase-1/química , Superóxido Dismutase-1/metabolismo , Substituição de Aminoácidos , Esclerose Amiotrófica Lateral/genética , Sítios de Ligação/genética , Biologia Computacional , Estabilidade Enzimática/genética , Humanos , Simulação de Dinâmica Molecular , Agregação Patológica de Proteínas/etiologia , Agregação Patológica de Proteínas/genética , Agregação Patológica de Proteínas/metabolismo , Dobramento de Proteína/efeitos dos fármacos , Modificação Traducional de Proteínas/efeitos dos fármacos , Modificação Traducional de Proteínas/genética , Estrutura Quaternária de Proteína , Superóxido Dismutase-1/genética
10.
Nat Commun ; 10(1): 3090, 2019 07 12.
Artigo em Inglês | MEDLINE | ID: mdl-31300647

RESUMO

The role of brain somatic mutations in Alzheimer's disease (AD) is not well understood. Here, we perform deep whole-exome sequencing (average read depth 584×) in 111 postmortem hippocampal formation and matched blood samples from 52 patients with AD and 11 individuals not affected by AD. The number of somatic single nucleotide variations (SNVs) in AD brain specimens increases significantly with aging, and the rate of mutation accumulation in the brain is 4.8-fold slower than that in AD blood. The putatively pathogenic brain somatic mutations identified in 26.9% (14 of 52) of AD individuals are enriched in PI3K-AKT, MAPK, and AMPK pathway genes known to contribute to hyperphosphorylation of tau. We show that a pathogenic brain somatic mutation in PIN1 leads to a loss-of-function mutation. In vitro mimicking of haploinsufficiency of PIN1 aberrantly increases tau phosphorylation and aggregation. This study provides new insights into the genetic architecture underlying the pathogenesis of AD.


Assuntos
Doença de Alzheimer/genética , Peptidilprolil Isomerase de Interação com NIMA/genética , Agregação Patológica de Proteínas/genética , Proteínas tau/metabolismo , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Envelhecimento/genética , Doença de Alzheimer/patologia , Animais , Linhagem Celular Tumoral , Feminino , Técnicas de Silenciamento de Genes , Haploinsuficiência , Hipocampo/citologia , Hipocampo/patologia , Humanos , Mutação com Perda de Função , Masculino , Camundongos , Pessoa de Meia-Idade , Taxa de Mutação , Peptidilprolil Isomerase de Interação com NIMA/metabolismo , Neurônios , Fosforilação/genética , Polimorfismo de Nucleotídeo Único , Agregação Patológica de Proteínas/patologia , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Sequenciamento Completo do Exoma
11.
PLoS One ; 14(7): e0219486, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31291334

RESUMO

The prominent characteristic of Alzheimer's disease (AD) is the accumulation of amyloid beta (Abeta) proteins in the form of plaques that cause molecular and cellular alterations in the brain. Due to the paucity of brain samples of early-stage Abeta aggregation, animal models have been developed to study early events in AD. Caenorhabditis elegans is a genetically tractable animal model for AD. Here, we used transcriptomic data, network-based protein-protein interactions and weighted gene co-expression network analysis (WGCNA), to detect modules and their gene ontology in response to Abeta aggregation in C. elegans. Additionally, hub genes and their orthologues in human and mouse were identified to study their relation to AD. We also found several transcription factors (TFs) responding to Abeta accumulation. Our results show that Abeta expression in C. elegans relates to general processes such as molting cycle, locomotion, and larval development plus AD-associated processes, including protein phosphorylation, and G-protein coupled receptor-regulated pathways. We reveal that many hub genes and TFs including ttbk-2, daf-16, and unc-49 have human and mouse orthologues that are directly or potentially associated with AD and neural development. In conclusion, using systems biology we identified important genes and biological processes in C. elegans that respond to Abeta aggregation, which could be used as potential diagnostic or therapeutic targets. In addition, because of evolutionary relationship to AD in human, we suggest that C. elegans is a useful model for studying early molecular events in AD.


Assuntos
Doença de Alzheimer/genética , Peptídeos beta-Amiloides/metabolismo , Proteínas de Caenorhabditis elegans/genética , Caenorhabditis elegans/genética , Redes Reguladoras de Genes , Doença de Alzheimer/patologia , Peptídeos beta-Amiloides/genética , Animais , Animais Geneticamente Modificados , Caenorhabditis elegans/metabolismo , Proteínas de Caenorhabditis elegans/metabolismo , Modelos Animais de Doenças , Perfilação da Expressão Gênica , Humanos , Agregação Patológica de Proteínas/genética , Agregação Patológica de Proteínas/patologia , Mapas de Interação de Proteínas , Homologia de Sequência do Ácido Nucleico , Biologia de Sistemas
12.
Nat Commun ; 10(1): 2479, 2019 06 06.
Artigo em Inglês | MEDLINE | ID: mdl-31171783

RESUMO

The tauopathy-like phenotype observed in the rTg4510 mouse line, in which human tauP301L expression specifically within the forebrain can be temporally controlled, has largely been attributed to high overexpression of mutant human tau in the forebrain region. Unexpectedly, we found that in a different mouse line with a targeted-insertion of the same transgene driven by the same tetracycline-TransActivator (tTA) allele, but with even higher overexpression of tauP301L than rTg4510, atrophy and tau histopathology are delayed, and a different behavioral profile is observed. This suggests that it is not overexpression of mutant human tau alone that contributes to the phenotype in rTg4510 mice. Furthermore we show that the tauopathy-like phenotype seen in rTg4510 requires a ~70-copy tau-transgene insertion in a 244 kb deletion in Fgf14, a ~7-copy tTA-transgene insertion in a 508 kb deletion that disrupts another five genes, in addition to high transgene overexpression. We propose that these additional effects need to be accounted for in any studies using rTg4510.


Assuntos
Modelos Animais de Doenças , Fatores de Crescimento de Fibroblastos/genética , Camundongos , Prosencéfalo/metabolismo , Agregação Patológica de Proteínas/genética , Tauopatias/genética , Proteínas tau/genética , Animais , Atrofia , Camundongos Transgênicos , Fenótipo , Prosencéfalo/patologia , Agregação Patológica de Proteínas/metabolismo , Agregação Patológica de Proteínas/patologia , Tauopatias/metabolismo , Tauopatias/patologia
13.
Nat Commun ; 10(1): 2493, 2019 06 07.
Artigo em Inglês | MEDLINE | ID: mdl-31175300

RESUMO

Tauopathies are neurodegenerative diseases characterized by intracellular amyloid deposits of tau protein. Missense mutations in the tau gene (MAPT) correlate with aggregation propensity and cause dominantly inherited tauopathies, but their biophysical mechanism driving amyloid formation is poorly understood. Many disease-associated mutations localize within tau's repeat domain at inter-repeat interfaces proximal to amyloidogenic sequences, such as 306VQIVYK311. We use cross-linking mass spectrometry, recombinant protein and synthetic peptide systems, in silico modeling, and cell models to conclude that the aggregation-prone 306VQIVYK311 motif forms metastable compact structures with its upstream sequence that modulates aggregation propensity. We report that disease-associated mutations, isomerization of a critical proline, or alternative splicing are all sufficient to destabilize this local structure and trigger spontaneous aggregation. These findings provide a biophysical framework to explain the basis of early conformational changes that may underlie genetic and sporadic tau pathogenesis.


Assuntos
Agregação Patológica de Proteínas/genética , Tauopatias/genética , Proteínas tau/genética , Motivos de Aminoácidos/genética , Simulação por Computador , Células HEK293 , Humanos , Espectrometria de Massas , Microscopia Eletrônica de Transmissão , Mutação de Sentido Incorreto , Agregação Patológica de Proteínas/metabolismo , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Proteínas Recombinantes/ultraestrutura , Proteínas tau/metabolismo , Proteínas tau/ultraestrutura
14.
Nat Struct Mol Biol ; 26(7): 619-627, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31235914

RESUMO

The DNA and RNA processing protein TDP-43 undergoes both functional and pathogenic aggregation. Functional TDP-43 aggregates form reversible, transient species such as nuclear bodies, stress granules, and myo-granules. Pathogenic, irreversible TDP-43 aggregates form in amyotrophic lateral sclerosis and other neurodegenerative conditions. Here we find the features of TDP-43 fibrils that confer both reversibility and irreversibility by determining structures of two segments reported to be the pathogenic cores of human TDP-43 aggregation: SegA (residues 311-360), which forms three polymorphs, all with dagger-shaped folds; and SegB A315E (residues 286-331 containing the amyotrophic lateral sclerosis hereditary mutation A315E), which forms R-shaped folds. Energetic analysis suggests that the dagger-shaped polymorphs represent irreversible fibril structures, whereas the SegB polymorph may participate in both reversible and irreversible fibrils. Our structures reveal the polymorphic nature of TDP-43 and suggest how the A315E mutation converts the R-shaped polymorph to an irreversible form that enhances pathology.


Assuntos
Amiloide/ultraestrutura , Proteínas de Ligação a DNA/ultraestrutura , Sequência de Aminoácidos , Amiloide/química , Amiloide/genética , Microscopia Crioeletrônica , Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/genética , Humanos , Modelos Moleculares , Mutação Puntual , Agregados Proteicos , Agregação Patológica de Proteínas/genética , Agregação Patológica de Proteínas/patologia , Conformação Proteica , Dobramento de Proteína , Estabilidade Proteica
15.
ACS Appl Mater Interfaces ; 11(26): 22973-22978, 2019 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-31252497

RESUMO

Misfolding and abnormal assembly of proteins cause many intractable diseases. The modulation of the assembly process of these proteins could contribute to understanding and controlling amyloid protein aggregation. Previous works focused mainly on the inhibition of the assembly process. To broaden the interaction modality of modulators with proteins for developing new modulators, in this work, we designed and synthesized two reactive poly ( p-phenylene vinylene) polymers, respectively, functionalized with N-hydroxysuccinimide ester (PPV-NHS) and pentafluorophenol ester (PPV-PFP), which exhibited the prevention or co-assembly effect on the aggregation process of islet amyloid polypeptide (IAPP). Cell assays demonstrated that both of the two polymers could effectively eliminate the cytotoxicity of IAPP. Moreover, PPV-NHS also could irreversibly disrupt preformed IAPP fibrils. We envision that PPV-NHS and PPV-PFP might offer a new design method for the modulation of protein assembly.


Assuntos
Polipeptídeo Amiloide das Ilhotas Pancreáticas/química , Polímeros/química , Agregação Patológica de Proteínas/tratamento farmacológico , Sequência de Aminoácidos/genética , Ésteres/síntese química , Ésteres/química , Ésteres/farmacologia , Fluorbenzenos/síntese química , Fluorbenzenos/química , Fluorbenzenos/farmacologia , Humanos , Polipeptídeo Amiloide das Ilhotas Pancreáticas/síntese química , Polipeptídeo Amiloide das Ilhotas Pancreáticas/farmacologia , Fenóis/síntese química , Fenóis/química , Fenóis/farmacologia , Polímeros/síntese química , Polímeros/farmacologia , Agregação Patológica de Proteínas/genética , Succinimidas/síntese química , Succinimidas/química , Succinimidas/farmacologia
16.
Biochem J ; 476(10): 1401-1417, 2019 05 21.
Artigo em Inglês | MEDLINE | ID: mdl-31036717

RESUMO

In Alzheimer's disease, tau is predominantly acetylated at K174, K274, K280, and K281 residues. The acetylation of K274-tau is linked with memory loss and dementia. In this study, we have examined the molecular mechanism of the toxicity of acetylated K274-tau. We incorporated an acetylation mimicking mutation at K274 (K→Q) residue of tau. The mutation (K274Q) strongly reduced the ability of tau to bind to tubulin and also to polymerize tubulin while K274R mutation did not reduce the ability of tau either to bind or polymerize tubulin. In addition, K274Q-tau displayed a higher aggregation propensity than wild-type tau as evident from thioflavin S fluorescence, tryptophan fluorescence, and electron microscopic images. Furthermore, dynamic light scattering, atomic force microscopy, and dot blot analysis using an oligomer-specific antibody suggested that K274Q mutation enhanced the oligomerization of tau. The K274Q mutation also strongly decreased the critical concentration for the liquid-liquid phase separation of tau. The oligomeric forms of K274Q-tau were found to be more toxic than wild tau to neuroblastoma cells. Using circular dichroism and fluorescence spectroscopy, we provide evidence indicating that the acetylation mimicking mutation (K274Q) induced conformational changes in tau. The results suggested that the acetylation of tau at 274 residues can increase tau aggregation and enhance the cytotoxicity of tau oligomers.


Assuntos
Mutação de Sentido Incorreto , Agregação Patológica de Proteínas , Tubulina (Proteína) , Proteínas tau , Acetilação , Substituição de Aminoácidos , Linhagem Celular Tumoral , Humanos , Agregação Patológica de Proteínas/genética , Agregação Patológica de Proteínas/metabolismo , Agregação Patológica de Proteínas/patologia , Tubulina (Proteína)/química , Tubulina (Proteína)/genética , Tubulina (Proteína)/metabolismo , Proteínas tau/química , Proteínas tau/genética , Proteínas tau/metabolismo
17.
Int J Mol Sci ; 20(9)2019 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-31071995

RESUMO

Human apolipoprotein E (apoE) is a major component of lipoprotein particles, and under physiological conditions, is involved in plasma cholesterol transport. Human apolipoprotein E found in three isoforms (E2; E3; E4) is a member of a family of apolipoproteins that under pathological conditions are detected in extracellular amyloid depositions in several amyloidoses. Interestingly, the lipid-free apoE form has been shown to be co-localized with the amyloidogenic Aß peptide in amyloid plaques in Alzheimer's disease, whereas in particular, the apoE4 isoform is a crucial risk factor for late-onset Alzheimer's disease. Evidence at the experimental level proves that apoE self-assembles into amyloid fibrilsin vitro, although the misfolding mechanism has not been clarified yet. Here, we explored the mechanistic insights of apoE misfolding by testing short apoE stretches predicted as amyloidogenic determinants by AMYLPRED, and we computationally investigated the dynamics of apoE and an apoE-Αß complex. Our in vitro biophysical results prove that apoE peptide-analogues may act as the driving force needed to trigger apoE aggregation and are supported by the computational apoE outcome. Additional computational work concerning the apoE-Αß complex also designates apoE amyloidogenic regions as important binding sites for oligomeric Αß; taking an important step forward in the field of Alzheimer's anti-aggregation drug development.


Assuntos
Doença de Alzheimer/genética , Peptídeos beta-Amiloides/química , Amiloidose/genética , Apolipoproteínas E/química , Doença de Alzheimer/patologia , Amiloide/química , Amiloide/genética , Amiloide/ultraestrutura , Peptídeos beta-Amiloides/genética , Peptídeos beta-Amiloides/ultraestrutura , Amiloidose/patologia , Apolipoproteínas E/ultraestrutura , Sítios de Ligação , Colesterol/química , Colesterol/genética , Humanos , Placa Amiloide/genética , Placa Amiloide/patologia , Placa Amiloide/ultraestrutura , Agregação Patológica de Proteínas/genética , Agregação Patológica de Proteínas/patologia , Dobramento de Proteína , Isoformas de Proteínas/química , Isoformas de Proteínas/genética , Isoformas de Proteínas/ultraestrutura
18.
BMC Biotechnol ; 19(1): 26, 2019 05 09.
Artigo em Inglês | MEDLINE | ID: mdl-31072369

RESUMO

BACKGROUND: Protein solubility characteristics are important determinants of success for recombinant proteins in relation to expression, purification, storage and administration. Escherichia coli offers a cost-efficient expression system. An important limitation, whether for biophysical studies or industrial-scale production, is the formation of insoluble protein aggregates in the cytoplasm. Several strategies have been implemented to improve soluble expression, ranging from modification of culture conditions to inclusion of solubility-enhancing tags. RESULTS: Surface patch analysis has been applied to predict amino acid changes that can alter the solubility of expressed recombinant human erythropoietin (rHuEPO) in E. coli, a factor that has importance for both yield and subsequent downstream processing of recombinant proteins. A set of rHuEPO proteins (rHuEPO E13K, F48D, R150D, and F48D/R150D) was designed (from the framework of wild-type protein, rHuEPO WT, via amino acid mutations) that varied in terms of positively-charged patches. A variant predicted to promote aggregation (rHuEPO E13K) decreased solubility significantly compared to rHuEPO WT. In contrast, variants predicted to diminish aggregation (rHuEPO F48D, R150D, and F48D/R150D) increased solubility up to 60% in relation to rHuEPO WT. CONCLUSIONS: These findings are discussed in the wider context of biophysical calculations applied to the family of EPO orthologues, yielding a diverse range of calculated values. It is suggested that combining such calculations with naturally-occurring sequence variation, and 3D model generation, could lead to a valuable tool for protein solubility design.


Assuntos
Eritropoetina/genética , Agregação Patológica de Proteínas/genética , Engenharia de Proteínas/métodos , Proteínas Recombinantes/genética , Eritropoetina/química , Eritropoetina/metabolismo , Humanos , Modelos Moleculares , Mutação , Agregação Patológica de Proteínas/metabolismo , Conformação Proteica , Estabilidade Proteica , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Propriedades de Superfície
19.
Cell Physiol Biochem ; 52(5): 970-983, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30977983

RESUMO

BACKGROUND/AIMS: Regulation of mRNA translation is central to protein homeostasis and is optimized for speed and accuracy. Spontaneous recoding events occur virtually at any codon but at very low frequency and are commonly assumed to increase as the cell ages. METHODS: Here, we leveraged the polyglutamine(polyQ)-frameshifting model of huntingtin exon 1 with CAG repeat length in the pathological range (Htt51Q), which undergoes enhanced non-programmed translational -1 frameshifting. RESULTS: In body muscle cells of Caenorhabditis elegans, -1 frameshifting occured at the onset of expression of the zero-frame product, correlated with mRNA level of the non-frameshifted expression and formed aggregates correlated with reduced motility in C. elegans. Spontaneous frameshifting was modulated by IFG-1, the homologue of the nutrient-responsive eukaryotic initiation factor 4G (eIF4G), under normal growth conditions and NSUN-5, a conserved ribosomal RNA methyltransferase, under osmotic stress. CONCLUSION: Our results suggest that frameshifting and aggregation occur at even early stages of development and, because of their intrinsic stability, may persist and accelerate the onset of age-related proteinopathies.


Assuntos
Proteínas de Caenorhabditis elegans , Caenorhabditis elegans , Mutação da Fase de Leitura , Proteína Huntingtina , Doença de Huntington , Expansão das Repetições de Trinucleotídeos , Animais , Caenorhabditis elegans/genética , Caenorhabditis elegans/metabolismo , Proteínas de Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/metabolismo , Modelos Animais de Doenças , Éxons , Humanos , Proteína Huntingtina/genética , Proteína Huntingtina/metabolismo , Doença de Huntington/genética , Doença de Huntington/metabolismo , Agregação Patológica de Proteínas/genética , Agregação Patológica de Proteínas/metabolismo
20.
J Biol Chem ; 294(19): 7917-7930, 2019 05 10.
Artigo em Inglês | MEDLINE | ID: mdl-30936201

RESUMO

Tauopathies are a diverse class of neurodegenerative diseases characterized by the formation of insoluble tau aggregates and the loss of cellular function and neuronal death. Tau inclusions have been shown to contain a number of proteins, including molecular chaperones, but the consequences of these entrapments are not well established. Here, using a human cell system for seeding-dependent tau aggregation, we demonstrate that the molecular chaperones heat-shock cognate 71-kDa protein (HSC70)/heat-shock protein 70 (HSP70), HSP90, and J-domain co-chaperones are sequestered by tau aggregates. By employing single-cell analysis of protein-folding and clathrin-mediated endocytosis, we show that both chaperone-dependent cellular activities are significantly impaired by tau aggregation and can be reversed by treatment with small-molecule regulators of heat-shock transcription factor 1 (HSF1) proteostasis that induce the expression of cytosolic chaperones. These results reveal that the sequestration of cytoplasmic molecular chaperones by tau aggregates interferes with two arms of the proteostasis network, likely having profound negative consequences for cellular function.


Assuntos
Vesículas Citoplasmáticas/metabolismo , Agregação Patológica de Proteínas/metabolismo , Dobramento de Proteína , Proteostase , Proteínas tau/metabolismo , Vesículas Citoplasmáticas/genética , Vesículas Citoplasmáticas/patologia , Células HEK293 , Proteínas de Choque Térmico HSC70/genética , Proteínas de Choque Térmico HSC70/metabolismo , Proteínas de Choque Térmico HSP90/genética , Proteínas de Choque Térmico HSP90/metabolismo , Fatores de Transcrição de Choque Térmico/genética , Fatores de Transcrição de Choque Térmico/metabolismo , Humanos , Agregação Patológica de Proteínas/genética , Agregação Patológica de Proteínas/patologia , Transporte Proteico , Proteínas tau/genética
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