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1.
Acta Neuropathol Commun ; 12(1): 99, 2024 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-38886865

RESUMO

Filaments made of residues 120-254 of transmembrane protein 106B (TMEM106B) form in an age-dependent manner and can be extracted from the brains of neurologically normal individuals and those of subjects with a variety of neurodegenerative diseases. TMEM106B filament formation requires cleavage at residue 120 of the 274 amino acid protein; at present, it is not known if residues 255-274 form the fuzzy coat of TMEM106B filaments. Here we show that a second cleavage appears likely, based on staining with an antibody raised against residues 263-274 of TMEM106B. We also show that besides the brain TMEM106B inclusions form in dorsal root ganglia and spinal cord, where they were mostly found in non-neuronal cells. We confirm that in the brain, inclusions were most abundant in astrocytes. No inclusions were detected in heart, liver, spleen or hilar lymph nodes. Based on their staining with luminescent conjugated oligothiophenes, we confirm that TMEM106B inclusions are amyloids. By in situ immunoelectron microscopy, TMEM106B assemblies were often found in structures resembling endosomes and lysosomes.


Assuntos
Proteínas de Membrana , Proteínas do Tecido Nervoso , Proteínas de Membrana/metabolismo , Humanos , Proteínas do Tecido Nervoso/metabolismo , Medula Espinal/metabolismo , Amiloide/metabolismo , Gânglios Espinais/metabolismo , Encéfalo/metabolismo , Masculino , Feminino , Sistema Nervoso Periférico/metabolismo , Idoso , Animais
2.
Proc Natl Acad Sci U S A ; 121(25): e2322572121, 2024 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-38875148

RESUMO

Shear forces affect self-assembly processes ranging from crystallization to fiber formation. Here, the effect of mild agitation on amyloid fibril formation was explored for four peptides and investigated in detail for A[Formula: see text]42, which is associated with Alzheimer's disease. To gain mechanistic insights into the effect of mild agitation, nonseeded and seeded aggregation reactions were set up at various peptide concentrations with and without an inhibitor. First, an effect on fibril fragmentation was excluded by comparing the monomer-concentration dependence of aggregation kinetics under idle and agitated conditions. Second, using a secondary nucleation inhibitor, Brichos, the agitation effect on primary nucleation was decoupled from secondary nucleation. Third, an effect on secondary nucleation was established in the absence of inhibitor. Fourth, an effect on elongation was excluded by comparing the seeding potency of fibrils formed under idle or agitated conditions. We find that both primary and secondary nucleation steps are accelerated by gentle agitation. The increased shear forces facilitate both the detachment of newly formed aggregates from catalytic surfaces and the rate at which molecules are transported in the bulk solution to encounter nucleation sites on the fibril and other surfaces. Ultrastructural evidence obtained with cryogenic transmission electron microscopy and free-flow electrophoresis in microfluidics devices imply that agitation speeds up the detachment of nucleated species from the fibril surface. Our findings shed light on the aggregation mechanism and the role of detachment for efficient secondary nucleation. The results inform on how to modulate the relative importance of different microscopic steps in drug discovery and investigations.


Assuntos
Amiloide , Amiloide/metabolismo , Amiloide/química , Cinética , Humanos , Resistência ao Cisalhamento , Agregados Proteicos , Peptídeos/química , Peptídeos/metabolismo , Doença de Alzheimer/metabolismo
3.
Open Biol ; 14(6): 230418, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38835240

RESUMO

Mutations in the protein superoxide dismutase-1 (SOD1) promote its misfolding and aggregation, ultimately causing familial forms of the debilitating neurodegenerative disease amyotrophic lateral sclerosis (ALS). Currently, over 220 (mostly missense) ALS-causing mutations in the SOD1 protein have been identified, indicating that common structural features are responsible for aggregation and toxicity. Using in silico tools, we predicted amyloidogenic regions in the ALS-associated SOD1-G85R mutant, finding seven regions throughout the structure. Introduction of proline residues into ß-strands II (I18P) or III (I35P) reduced the aggregation propensity and toxicity of SOD1-G85R in cells, significantly more so than proline mutations in other amyloidogenic regions. The I18P and I35P mutations also reduced the capability of SOD1-G85R to template onto previously formed non-proline mutant SOD1 aggregates as measured by fluorescence recovery after photobleaching. Finally, we found that, while the I18P and I35P mutants are less structurally stable than SOD1-G85R, the proline mutants are less aggregation-prone during proteasome inhibition, and less toxic to cells overall. Our research highlights the importance of a previously underappreciated SOD1 amyloidogenic region in ß-strand II (15QGIINF20) to the aggregation and toxicity of SOD1 in ALS mutants, and suggests that ß-strands II and III may be good targets for the development of SOD1-associated ALS therapies.


Assuntos
Esclerose Lateral Amiotrófica , Agregados Proteicos , Superóxido Dismutase-1 , Superóxido Dismutase-1/metabolismo , Superóxido Dismutase-1/genética , Superóxido Dismutase-1/química , Humanos , Esclerose Lateral Amiotrófica/metabolismo , Esclerose Lateral Amiotrófica/genética , Esclerose Lateral Amiotrófica/patologia , Agregação Patológica de Proteínas/genética , Agregação Patológica de Proteínas/metabolismo , Mutação , Conformação Proteica em Folha beta , Modelos Moleculares , Prolina/metabolismo , Amiloide/metabolismo , Amiloide/química , Dobramento de Proteína
4.
Radiology ; 311(3): e231442, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38860897

RESUMO

Background Visual assessment of amyloid PET scans relies on the availability of radiologist expertise, whereas quantification of amyloid burden typically involves MRI for processing and analysis, which can be computationally expensive. Purpose To develop a deep learning model to classify minimally processed brain PET scans as amyloid positive or negative, evaluate its performance on independent data sets and different tracers, and compare it with human visual reads. Materials and Methods This retrospective study used 8476 PET scans (6722 patients) obtained from late 2004 to early 2023 that were analyzed across five different data sets. A deep learning model, AmyloidPETNet, was trained on 1538 scans from 766 patients, validated on 205 scans from 95 patients, and internally tested on 184 scans from 95 patients in the Alzheimer's Disease Neuroimaging Initiative (ADNI) fluorine 18 (18F) florbetapir (FBP) data set. It was tested on ADNI scans using different tracers and scans from independent data sets. Scan amyloid positivity was based on mean cortical standardized uptake value ratio cutoffs. To compare with model performance, each scan from both the Centiloid Project and a subset of the Anti-Amyloid Treatment in Asymptomatic Alzheimer's Disease (A4) study were visually interpreted with a confidence level (low, intermediate, high) of amyloid positivity/negativity. The area under the receiver operating characteristic curve (AUC) and other performance metrics were calculated, and Cohen κ was used to measure physician-model agreement. Results The model achieved an AUC of 0.97 (95% CI: 0.95, 0.99) on test ADNI 18F-FBP scans, which generalized well to 18F-FBP scans from the Open Access Series of Imaging Studies (AUC, 0.95; 95% CI: 0.93, 0.97) and the A4 study (AUC, 0.98; 95% CI: 0.98, 0.98). Model performance was high when applied to data sets with different tracers (AUC ≥ 0.97). Other performance metrics provided converging evidence. Physician-model agreement ranged from fair (Cohen κ = 0.39; 95% CI: 0.16, 0.60) on a sample of mostly equivocal cases from the A4 study to almost perfect (Cohen κ = 0.93; 95% CI: 0.86, 1.0) on the Centiloid Project. Conclusion The developed model was capable of automatically and accurately classifying brain PET scans as amyloid positive or negative without relying on experienced readers or requiring structural MRI. Clinical trial registration no. NCT00106899 © RSNA, 2024 Supplemental material is available for this article. See also the editorial by Bryan and Forghani in this issue.


Assuntos
Doença de Alzheimer , Encéfalo , Aprendizado Profundo , Tomografia por Emissão de Pósitrons , Humanos , Tomografia por Emissão de Pósitrons/métodos , Estudos Retrospectivos , Doença de Alzheimer/diagnóstico por imagem , Doença de Alzheimer/metabolismo , Doença de Alzheimer/classificação , Masculino , Feminino , Idoso , Encéfalo/diagnóstico por imagem , Encéfalo/metabolismo , Amiloide/metabolismo , Idoso de 80 Anos ou mais
5.
Heart Fail Clin ; 20(3): 249-260, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38844296

RESUMO

Amyloidosis is a heterogenous group of disorders, caused by the deposition of insoluble fibrils derived from misfolded proteins in the extracellular space of various organs. These proteins have an unstable structure that causes them to misfold, aggregate, and deposit as amyloid fibrils with the pathognomonic histologic property of green birefringence when viewed under cross-polarized light after staining with Congo red. Amyloid fibrils are insoluble and degradation-resistant; resistance to catabolism results in progressive tissue amyloid accumulation. The outcome of this process is organ disfunction independently from the type of deposited protein, however there can be organ that are specifically targeted from certain proteins.


Assuntos
Amiloide , Amiloidose , Humanos , Amiloidose/metabolismo , Amiloidose/patologia , Amiloide/metabolismo
6.
Nat Commun ; 15(1): 5121, 2024 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-38879609

RESUMO

Systemic AL amyloidosis is one of the most frequently diagnosed forms of systemic amyloidosis. It arises from mutational changes in immunoglobulin light chains. To explore whether these mutations may affect the structure of the formed fibrils, we determine and compare the fibril structures from several patients with cardiac AL amyloidosis. All patients are affected by light chains that contain an IGLV3-19 gene segment, and the deposited fibrils differ by the mutations within this common germ line background. Using cryo-electron microscopy, we here find different fibril structures in each patient. These data establish that the mutations of amyloidogenic light chains contribute to defining the fibril architecture and hence the structure of the pathogenic agent.


Assuntos
Microscopia Crioeletrônica , Cadeias Leves de Imunoglobulina , Amiloidose de Cadeia Leve de Imunoglobulina , Mutação , Humanos , Amiloidose de Cadeia Leve de Imunoglobulina/genética , Amiloidose de Cadeia Leve de Imunoglobulina/patologia , Cadeias Leves de Imunoglobulina/genética , Cadeias Leves de Imunoglobulina/metabolismo , Cadeias Leves de Imunoglobulina/química , Amiloide/metabolismo , Amiloide/genética , Amiloide/ultraestrutura , Masculino , Feminino , Pessoa de Meia-Idade
7.
ACS Nano ; 18(24): 15815-15830, 2024 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-38833572

RESUMO

Amyloid-like fibrils are garnering keen interest in biotechnology as supramolecular nanofunctional units to be used as biomimetic platforms to control cell behavior. Recent insights into fibril functionality have highlighted their importance in tissue structure, mechanical properties, and improved cell adhesion, emphasizing the need for scalable and high-kinetics fibril synthesis. In this study, we present the instantaneous and bulk formation of amyloid-like nanofibrils from human platelet lysate (PL) using the ionic liquid cholinium tosylate as a fibrillating agent. The instant fibrillation of PL proteins upon supramolecular protein-ionic liquid interactions was confirmed from the protein conformational transition toward cross-ß-sheet-rich structures. These nanofibrils were utilized as building blocks for the formation of thin and flexible free-standing membranes via solvent casting to support cell self-aggregation. These PL-derived fibril membranes reveal a nanotopographically rough surface and high stability over 14 days under cell culture conditions. The culture of mesenchymal stem cells or tumor cells on the top of the membrane demonstrated that cells are able to adhere and self-organize in a three-dimensional (3D) spheroid-like microtissue while tightly folding the fibril membrane. Results suggest that nanofibril membrane incorporation in cell aggregates can improve cell viability and metabolic activity, recreating native tissues' organization. Altogether, these PL-derived nanofibril membranes are suitable bioactive platforms to generate 3D cell-guided microtissues, which can be explored as bottom-up strategies to faithfully emulate native tissues in a fully human microenvironment.


Assuntos
Plaquetas , Nanofibras , Humanos , Plaquetas/metabolismo , Plaquetas/química , Nanofibras/química , Células-Tronco Mesenquimais/citologia , Células-Tronco Mesenquimais/metabolismo , Agregação Celular/efeitos dos fármacos , Adesão Celular/efeitos dos fármacos , Amiloide/química , Amiloide/metabolismo , Membranas Artificiais
8.
Sci Rep ; 14(1): 13746, 2024 06 14.
Artigo em Inglês | MEDLINE | ID: mdl-38877049

RESUMO

Apolipoprotein E (ApoE) is involved in cholesterol transport among cells and also plays an important role in amyloid formation, co-depositing with amyloid fibrils in various types of amyloidosis. Although the in vivo amyloidogenicity of ApoE has not been previously demonstrated, this study provides evidence of ApoE amyloidogenicity in leopard geckos (Eublepharis macularius), belonging to the class Reptilia. Histologically, amyloid deposits were localized within cholesterol granulomas and exhibited positive Congo red staining, with yellow to green birefringence under polarized light. On mass spectrometry-based proteomic analysis, ApoE was detected as a dominant component of amyloid; of the full length of the 274 amino acid residues, peptides derived from Leu185-Arg230 were frequently detected with non-tryptic truncations. Immunohistochemistry with anti-leopard gecko ApoE antibody showed positive reactions of amyloid deposits. These results show that ApoE is an amyloid precursor protein within the cholesterol granulomas of leopard geckos. Although further investigations are needed, the C-terminal region of ApoE involved in amyloid formation is a lipid-binding region, and there should be a relationship between amyloidogenesis and the development of cholesterol granulomas in leopard geckos. This study provides novel insights into the pathogenesis of ApoE-related diseases.


Assuntos
Amiloide , Apolipoproteínas E , Colesterol , Lagartos , Animais , Lagartos/metabolismo , Colesterol/metabolismo , Apolipoproteínas E/metabolismo , Amiloide/metabolismo , Granuloma/metabolismo , Granuloma/patologia , Proteômica/métodos
9.
Neurobiol Dis ; 198: 106553, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38839022

RESUMO

α-Synuclein (α-syn) is a small protein that is involved in cell vesicle trafficking in neuronal synapses. A progressive aggregation of this protein is the expected molecular cause of Parkinson's disease, a disease that affects millions of people around the world. A growing body of evidence indicates that phospholipids can strongly accelerate α-syn aggregation and alter the toxicity of α-syn oligomers and fibrils formed in the presence of lipid vesicles. This effect is attributed to the presence of high copies of lysines in the N-terminus of the protein. In this study, we performed site-directed mutagenesis and replaced one out of two lysines at each of the five sites located in the α-syn N-terminus. Using several biophysical and cellular approaches, we investigated the extent to which six negatively charged fatty acids (FAs) could alter the aggregation properties of K10A, K23A, K32A, K43A, and K58A α-syn. We found that FAs uniquely modified the aggregation properties of K43A, K58A, and WT α-syn, as well as changed morphology of amyloid fibrils formed by these mutants. At the same time, FAs failed to cause substantial changes in the aggregation rates of K10A, K23A, and K32A α-syn, as well as alter the morphology and toxicity of the corresponding amyloid fibrils. Based on these results, we can conclude that K10, K23, and K32 amino acid residues play a critical role in protein-lipid interactions since their replacement on non-polar alanines strongly suppressed α-syn-lipid interactions.


Assuntos
Mutagênese Sítio-Dirigida , alfa-Sinucleína , alfa-Sinucleína/metabolismo , alfa-Sinucleína/genética , Humanos , Amiloide/metabolismo , Amiloide/genética , Ácidos Graxos/metabolismo
10.
PLoS One ; 19(6): e0304891, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38843135

RESUMO

ATTR amyloidosis is caused by deposition of large, insoluble aggregates (amyloid fibrils) of cross-ß-sheet TTR protein molecules on the intercellular surfaces of tissues. The process of amyloid formation from monomeric TTR protein molecules to amyloid deposits has not been fully characterized and is therefore modeled in this paper. Two models are considered: 1) TTR monomers in the blood spontaneously fold into a ß-sheet conformation, aggregate into short proto-fibrils that then circulate in the blood until they find a complementary tissue where the proto-fibrils accumulate to form the large, insoluble amyloid fibrils found in affected tissues. 2) TTR monomers in the native or ß-sheet conformation circulate in the blood until they find a tissue binding site and deposit in the tissue or tissues forming amyloid deposits in situ. These models only differ on where the selection for ß-sheet complementarity occurs, in the blood where wt-wt, wt-v, and v-v interactions determine selectivity, or on the tissue surface where tissue-wt and tissure-v interactions also determine selectivity. Statistical modeling in both cases thus involves selectivity in fibril aggregation and tissue binding. Because binding of protein molecules into fibrils and binding of fibrils to tissues occurs through multiple weak non-covalent bonds, strong complementarity between ß-sheet molecules and between fibrils and tissues is required to explain the insolubility and tissue selectivity of ATTR amyloidosis. Observation of differing tissue selectivity and thence disease phenotypes from either pure wildtype TTR protein or a mix of wildtype and variant molecules in amyloid fibrils evidences the requirement for fibril-tissue complementarity. Understanding the process that forms fibrils and binds fibrils to tissues may lead to new possibilities for interrupting the process and preventing or curing ATTR amyloidosis.


Assuntos
Amiloide , Pré-Albumina , Pré-Albumina/metabolismo , Pré-Albumina/química , Humanos , Amiloide/metabolismo , Amiloide/química , Neuropatias Amiloides Familiares/metabolismo , Neuropatias Amiloides Familiares/patologia , Amiloidose/metabolismo , Modelos Moleculares , Conformação Proteica em Folha beta
11.
J Mol Biol ; 436(12): 168607, 2024 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-38734203

RESUMO

Polyglutamine (polyQ) sequences undergo repeat-length dependent formation of disease-associated, amyloid-like cross-ß core structures with kinetics and aggregate morphologies often influenced by the flanking sequences. In Huntington's disease (HD), the httNT segment on the polyQ's N-terminal flank enhances aggregation rates by changing amyloid nucleation from a classical homogeneous mechanism to a two-step process requiring an ɑ-helix-rich oligomeric intermediate. A folded, helix-rich httNT tetrameric structure suggested to be this critical intermediate was recently reported. Here we employ single alanine replacements along the httNT sequence to assess this proposed structure and refine the mechanistic model. We find that Ala replacement of hydrophobic residues within simple httNT peptides greatly suppresses helicity, supporting the tetramer model. These same helix-disruptive replacements in the httNT segment of an exon-1 analog greatly reduce aggregation kinetics, suggesting that an ɑ-helix rich multimer - either the tetramer or a larger multimer - plays an on-pathway role in nucleation. Surprisingly, several other Ala replacements actually enhance helicity and/or amyloid aggregation. The spatial localization of these residues on the tetramer surface suggests a self-association interface responsible for formation of the octomers and higher-order multimers most likely required for polyQ amyloid nucleation. Multimer docking of the tetramer, using the protein-protein docking algorithm ClusPro, predicts this symmetric surface to be a viable tetramer dimerization interface. Intriguingly, octomer formation brings the emerging polyQ chains into closer proximity at this tetramer-tetramer interface. Further supporting the potential importance of tetramer super-assembly, computational docking with a known exon-1 aggregation inhibitor predicts ligand contacts with residues at this interface.


Assuntos
Amiloide , Éxons , Proteína Huntingtina , Peptídeos , Multimerização Proteica , Proteína Huntingtina/química , Proteína Huntingtina/metabolismo , Proteína Huntingtina/genética , Humanos , Amiloide/química , Amiloide/metabolismo , Peptídeos/química , Peptídeos/metabolismo , Doença de Huntington/metabolismo , Doença de Huntington/genética , Cinética , Interações Hidrofóbicas e Hidrofílicas , Agregados Proteicos , Modelos Moleculares
12.
Proc Natl Acad Sci U S A ; 121(23): e2316734121, 2024 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-38805292

RESUMO

The RNA tailing machinery adds nucleotides to the 3'-end of RNA molecules that are implicated in various biochemical functions, including protein synthesis and RNA stability. Here, we report a role for the RNA tailing machinery as enzymatic modifiers of intracellular amyloidogenesis. A targeted RNA interference screen identified Terminal Nucleotidyl-transferase 4b (TENT4b/Papd5) as an essential participant in the amyloidogenic phase transition of nucleoli into solid-like Amyloid bodies. Full-length-and-mRNA sequencing uncovered starRNA, a class of unusually long untemplated RNA molecules synthesized by TENT4b. StarRNA consists of short rRNA fragments linked to long, linear mixed tails that operate as polyanionic stimulators of amyloidogenesis in cells and in vitro. Ribosomal intergenic spacer noncoding RNA (rIGSRNA) recruit TENT4b in intranucleolar foci to coordinate starRNA synthesis driving their amyloidogenic phase transition. The exoribonuclease RNA Exosome degrades starRNA and functions as a general suppressor of cellular amyloidogenesis. We propose that amyloidogenic phase transition is under tight enzymatic control by the RNA tailing and exosome axis.


Assuntos
Amiloide , Transição de Fase , Humanos , Amiloide/metabolismo , Estabilidade de RNA , RNA/metabolismo , RNA/genética , Polirribonucleotídeo Nucleotidiltransferase/metabolismo , Polirribonucleotídeo Nucleotidiltransferase/genética
13.
Prog Mol Biol Transl Sci ; 206: 111-141, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38811079

RESUMO

Protein oligomers, widely found in nature, have significant physiological and pathological functions. They are classified into three groups based on their function and toxicity. Significant advancements are being achieved in the development of functional oligomers, with a focus on various applications and their engineering. The antimicrobial peptides oligomers play roles in death of bacterial and cancer cells. The predominant pathogenic species in neurodegenerative disorders, as shown by recent results, are amyloid oligomers, which are the main subject of this chapter. They are generated throughout the aggregation process, serving as both intermediates in the subsequent aggregation pathways and ultimate products. Some of them may possess potent cytotoxic properties and through diverse mechanisms cause cellular impairment, and ultimately, the death of cells and disease progression. Information regarding their structure, formation mechanism, and toxicity is limited due to their inherent instability and structural variability. This chapter aims to provide a concise overview of the current knowledge regarding amyloid oligomers.


Assuntos
Amiloide , Multimerização Proteica , Humanos , Animais , Amiloide/metabolismo , Amiloide/química
14.
Prog Mol Biol Transl Sci ; 206: 143-182, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38811080

RESUMO

Liquid-liquid phase separation (LLPS) refers to the phenomenon, where a homogeneous solution spontaneously undergoes a transition into two or more immiscible phases. Through transient weak multivalent macromolecular interactions, a homogeneous solution can spontaneously separate into two phases: one rich in biomolecules and the other poor in biomolecules. Phase separation is believed to serve as the physicochemical foundation for the formation of membrane-less organelles (MLOs) and bio-molecular condensates within cells. Moreover, numerous biological processes depend on LLPS, such as transcription, immunological response, chromatin architecture, DNA damage response, stress granule formation, viral infection, etc. Abnormalities in phase separation can lead to diseases, such as cancer, neurodegeneration, and metabolic disorders. LLPS is regulated by various factors, such as concentration of molecules undergoing LLPS, salt concentration, pH, temperature, post-translational modifications, and molecular chaperones. Recent research on LLPS of biomolecules has progressed rapidly and led to the development of databases containing information pertaining to various aspects of the biomolecule separation analysis. However, more comprehensive research is still required to fully comprehend the specific molecular mechanisms and biological effects of LLPS.


Assuntos
Transição de Fase , Humanos , Animais , Extração Líquido-Líquido , Amiloide/química , Amiloide/metabolismo , Separação de Fases
15.
Prog Mol Biol Transl Sci ; 206: 291-340, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38811084

RESUMO

Many diseases are caused by misfolded and denatured proteins, leading to neurodegenerative diseases. In recent decades researchers have developed a variety of compounds, including polymeric inhibitors and natural compounds, antibodies, and chaperones, to inhibit protein aggregation, decrease the toxic effects of amyloid fibrils, and facilitate refolding proteins. The causes and mechanisms of amyloid formation are still unclear, and there are no effective treatments for Amyloid diseases. This section describes research and achievements in the field of inhibiting amyloid accumulation and also discusses the importance of various strategies in facilitating the removal of aggregates species (refolding) in the treatment of neurological diseases such as chemical methods like as, small molecules, metal chelators, polymeric inhibitors, and nanomaterials, as well as the use of biomolecules (peptide and, protein, nucleic acid, and saccharide) as amyloid inhibitors, are also highlighted.


Assuntos
Amiloide , Humanos , Amiloide/metabolismo , Amiloide/química , Animais , Agregados Proteicos/efeitos dos fármacos
16.
Prog Mol Biol Transl Sci ; 206: 183-227, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38811081

RESUMO

Amyloid fibrils are insoluble proteins with intricate ß-sheet structures associated with various human diseases, including Parkinson's, Alzheimer's, and prion diseases. Proteins can form aggregates when their structure is misfolded, resulting in highly organized amyloid fibrils or amorphous aggregates. The formation of protein aggregates is a promising research field for mitigating diseases and the pharmaceutical and food industries. It is important to monitor and minimize the appearance of aggregates in these protein products. Several methods exist to assess protein aggregation, that includes from basic investigations to advanced biophysical techniques. Physicochemical parameters such as molecular weight, conformation, structure, and dimension are examined to study aggregation. There is an urgent need to develop methods for the detection of protein aggregation and amyloid fibril formation both in vitro and in vivo. This chapter focuses on a comprehensive discussion of the methods used to characterize and evaluate aggregates and amyloid fibrils.


Assuntos
Amiloide , Amiloide/química , Amiloide/metabolismo , Humanos , Agregados Proteicos , Animais
17.
Prog Mol Biol Transl Sci ; 206: 55-83, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38811089

RESUMO

Protein aggregation is a complex process with several stages that lead to the formation of complex structures and shapes with a broad variability in stability and toxicity. The aggregation process is affected by various factors and environmental conditions that disrupt the protein's original state, including internal factors like mutations, expression levels, and polypeptide chain truncation, as well as external factors, such as dense molecular surroundings, post-translation modifications, and interactions with other proteins, nucleic acids, small molecules, metal ions, chaperones, and lipid membranes. During the aggregation process, the biological activity of an aggregating protein may be reduced or eliminated, whereas the resulting aggregates may have the potential to be immunogenic, or they may have other undesirable properties. Finding the cause(s) of protein aggregation and controlling it to an acceptable level is among the most crucial topics of research in academia and biopharmaceutical companies. This chapter aims to review intrinsic pathways of protein aggregation and potential extrinsic variables that influence this process.


Assuntos
Amiloide , Amiloide/metabolismo , Humanos , Animais , Agregados Proteicos
18.
Prog Mol Biol Transl Sci ; 206: 389-434, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38811086

RESUMO

While amyloid has traditionally been viewed as a harmful formation, emerging evidence suggests that amyloids may also play a functional role in cell biology, contributing to normal physiological processes that have been conserved throughout evolution. Functional amyloids have been discovered in several creatures, spanning from bacteria to mammals. These amyloids serve a multitude of purposes, including but not limited to, forming biofilms, melanin synthesis, storage, information transfer, and memory. The functional role of amyloids has been consistently validated by the discovery of more functional amyloids, indicating a conceptual convergence. The biology of amyloids is well-represented by non-pathogenic amyloids, given the numerous ones already identified and the ongoing rate of new discoveries. In this chapter, functional amyloids in microorganisms, animals, and plants are described.


Assuntos
Amiloide , Amiloide/metabolismo , Animais , Humanos
19.
Methods Enzymol ; 697: 181-209, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38816123

RESUMO

While enzymes are potentially useful in various applications, their limited operational stability and production costs have led to an extensive search for stable catalytic agents that will retain the efficiency, specificity, and environmental-friendliness of natural enzymes. Despite extensive efforts, there is still an unmet need for improved enzyme mimics and novel concepts to discover and optimize such agents. Inspired by the catalytic activity of amyloids and the formation of amyloid-like assemblies by metabolites, our group pioneered the development of novel metabolite-metal co-assemblies (bio-nanozymes) that produce nanomaterials mimicking the catalytic function of common metalloenzymes that are being used for various technological applications. In addition to their notable activity, bio-nanozymes are remarkably safe as they are purely composed of amino acids and minerals that are harmless to the environment. The bio-nanozymes exhibit high efficiency and exceptional robustness, even under extreme conditions of temperature, pH, and salinity that are impractical for enzymes. Our group has recently also demonstrated the formation of ordered amino acid co-assemblies showing selective and preferential interactions comparable to the organization of residues in folded proteins. The identified bio-nanozymes can be used in various applications including environmental remediation, synthesis of new materials, and green energy.


Assuntos
Aminoácidos , Amiloide , Aminoácidos/química , Aminoácidos/metabolismo , Amiloide/química , Amiloide/metabolismo , Catálise , Nanoestruturas/química , Metais/química
20.
Methods Enzymol ; 697: 1-13, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38816119

RESUMO

Kinetic characterization of catalytic amyloids arguably presents a most challenging type of kinetic experiment where careful consideration of many factors is required. Here we outline common pitfalls in devising kinetic studies in such systems. Unlike the more specific protocols for various applications described in this volume, this chapter deals with general issues in setting up kinetic experiments that are incredibly important but often go without explicit mention in the specialized literature. The kinetic fundamentals described here can be also be of use to the enzymologists working with more traditional catalysts.


Assuntos
Amiloide , Cinética , Amiloide/química , Amiloide/metabolismo , Humanos , Catálise , Biocatálise
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