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1.
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
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.
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
4.
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
5.
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
6.
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
7.
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
8.
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
9.
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
10.
Methods Enzymol ; 697: 113-150, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38816120

RESUMO

The self-assembly of proteins and peptides into ordered structures called amyloid fibrils is a hallmark of numerous diseases, impacting the brain, heart, and other organs. The structure of amyloid aggregates is central to their function and thus has been extensively studied. However, the structural heterogeneities between aggregates as they evolve throughout the aggregation pathway are still not well understood. Conventional biophysical spectroscopic methods are bulk techniques and only report on the average structural parameters. Understanding the structure of individual aggregate species in a heterogeneous ensemble necessitates spatial resolution on the length scale of the aggregates. Recent technological advances have led to augmentation of infrared (IR) spectroscopy with imaging modalities, wherein the photothermal response of the sample upon vibrational excitation is leveraged to provide spatial resolution beyond the diffraction limit. These combined approaches are ideally suited to map out the structural heterogeneity of amyloid ensembles. AFM-IR, which integrates IR spectroscopy with atomic force microscopy enables identification of the structural facets the oligomers and fibrils at individual aggregate level with nanoscale resolution. These capabilities can be extended to chemical mapping in diseased tissue specimens with submicron resolution using optical photothermal microscopy, which combines IR spectroscopy with optical imaging. This book chapter provides the basic premise of these novel techniques and provides the typical methodology for using these approaches for amyloid structure determination. Detailed procedures pertaining to sample preparation and data acquisition and analysis are discussed and the aggregation of the amyloid ß peptide is provided as a case study to provide the reader the experimental parameters necessary to use these techniques to complement their research efforts.


Assuntos
Amiloide , Microscopia de Força Atômica , Espectrofotometria Infravermelho , Humanos , Espectrofotometria Infravermelho/métodos , Microscopia de Força Atômica/métodos , Amiloide/química , Agregados Proteicos , Peptídeos beta-Amiloides/química , Peptídeos beta-Amiloides/metabolismo , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Animais
11.
Proc Natl Acad Sci U S A ; 121(23): e2401458121, 2024 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-38809711

RESUMO

Patients with type 1 diabetes mellitus who are dependent on an external supply of insulin develop insulin-derived amyloidosis at the sites of insulin injection. A major component of these plaques is identified as full-length insulin consisting of the two chains A and B. While there have been several reports that characterize insulin misfolding and the biophysical properties of the fibrils, atomic-level information on the insulin fibril architecture remains elusive. We present here an atomic resolution structure of a monomorphic insulin amyloid fibril that has been determined using magic angle spinning solid-state NMR spectroscopy. The structure of the insulin monomer yields a U-shaped fold in which the two chains A and B are arranged in parallel to each other and are oriented perpendicular to the fibril axis. Each chain contains two ß-strands. We identify two hydrophobic clusters that together with the three preserved disulfide bridges define the amyloid core structure. The surface of the monomeric amyloid unit cell is hydrophobic implicating a potential dimerization and oligomerization interface for the assembly of several protofilaments in the mature fibril. The structure provides a starting point for the development of drugs that bind to the fibril surface and disrupt secondary nucleation as well as for other therapeutic approaches to attenuate insulin aggregation.


Assuntos
Amiloide , Insulina , Humanos , Amiloide/química , Amiloide/metabolismo , Insulina/química , Insulina/metabolismo , Modelos Moleculares , Interações Hidrofóbicas e Hidrofílicas , Diabetes Mellitus Tipo 1/tratamento farmacológico , Conformação Proteica , Espectroscopia de Ressonância Magnética
12.
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
13.
Neurosci Lett ; 833: 137825, 2024 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-38768939

RESUMO

Alzheimer's disease (AD) is a prevalent form of dementia in the elderly. There is currently no effective treatment available for this disease. Diagnosis of AD typically relies on clinical manifestations and specific biomarkers. The present study investigated the impact of inducing Alzheimer's disease (AD) in mice through the injection of lysozyme amyloids formed in the presence or absence of Bis (Indolyl) phenylmethane (BIPM) on alterations in plasma lipid profiles and liver enzyme activities. 24 adult Wistar rats were divided into control, Scopolamine, Lysozyme, BIPM groups and the blood samples were obtained from the groups for biochemical analysis. The findings of the study revealed significant changes in the plasma lipid profiles and liver enzyme markers of the Lysozyme group compared to the control group. The Lysozyme group exhibited elevated triglycerides (n = 6, P < 0.02) and LDL levels (n = 6, P < 0.02), reduced HDL (n = 6, P < 0.05) and cholesterol levels (n = 6, P < 0.02), and altered serum glutamic oxaloacetic transaminase (SGOT) level (n = 6, P < 0.05) compared to controls. While the level of serum glutamic pyruvic transaminase (SGPT) did not change significantly compared to the control. BIPM groups showed no significant changes in lipid or enzyme levels compared to controls. Overall, our research has shown that BIPM has the ability to modify the structure of HEWL aggregates, thereby improving the detrimental effects associated with AD caused by these aggregates. Analyzing lipid profiles and liver enzyme markers presents a promising avenue for targeted therapeutic approaches. These alterations observed in the plasma may potentially serve as candidate biomarkers for diagnosing this disease.


Assuntos
Doença de Alzheimer , Modelos Animais de Doenças , Hipocampo , Lipídeos , Fígado , Muramidase , Ratos Wistar , Animais , Doença de Alzheimer/tratamento farmacológico , Doença de Alzheimer/metabolismo , Doença de Alzheimer/sangue , Fígado/efeitos dos fármacos , Fígado/metabolismo , Muramidase/sangue , Muramidase/metabolismo , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Lipídeos/sangue , Camundongos , Masculino , Indóis/administração & dosagem , Indóis/farmacologia , Amiloide/metabolismo , Ratos
14.
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
15.
Prog Mol Biol Transl Sci ; 206: 265-290, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38811083

RESUMO

Misfolded proteins assemble into fibril structures that are called amyloids. Unlike usually folded proteins, misfolded fibrils are insoluble and deposit extracellularly or intracellularly. Misfolded proteins interrupt the function and structure of cells and cause amyloid disease. There is increasing evidence that the most pernicious species are oligomers. Misfolded proteins disrupt cell function and cause cytotoxicity by calcium imbalance, mitochondrial dysfunction, and intracellular reactive oxygen species. Despite profound impacts on health, social, and economic factors, amyloid diseases remain untreatable. To develop new therapeutics and to understand the pathological manifestations of amyloidosis, research into the origin and pathology of amyloidosis is urgently needed. This chapter describes the basic concept of amyloid disease and the function of atypical amyloid deposits in them.


Assuntos
Amiloide , Humanos , Amiloide/metabolismo , Animais , Amiloidose/patologia , Amiloidose/metabolismo
16.
Prog Mol Biol Transl Sci ; 206: 341-388, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38811085

RESUMO

A family of maladies known as amyloid disorders, proteinopathy, or amyloidosis, are characterized by the accumulation of abnormal protein aggregates containing cross-ß-sheet amyloid fibrils in many organs and tissues. Often, proteins that have been improperly formed or folded make up these fibrils. Nowadays, most treatments for amyloid illness focus on managing symptoms rather than curing or preventing the underlying disease process. However, recent advances in our understanding of the biology of amyloid diseases have led to the development of innovative therapies that target the emergence and accumulation of amyloid fibrils. Examples of these treatments include the use of small compounds, monoclonal antibodies, gene therapy, and others. In the end, even if the majority of therapies for amyloid diseases are symptomatic, greater research into the biology behind these disorders is identifying new targets for potential therapy and paving the way for the development of more effective treatments in the future.


Assuntos
Amiloidose , Humanos , Animais , Amiloidose/terapia , Amiloidose/patologia , Amiloide/metabolismo , Deficiências na Proteostase/terapia , Terapia Genética
17.
Prog Mol Biol Transl Sci ; 206: 1-10, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38811077

RESUMO

In order for an ordered protein to perform its specific function, it must have a specific molecular structure. Information about this structure is encoded in the protein's amino acid sequence. The unique functional state is achieved as a result of a specific process, known as protein folding. However, as a result of partial or complete unfolding of the polypeptide chain, proteins may misfold and aggregate, leading to the formation of various aggregated structures, such as like amyloid aggregates with the cross-ß structure. A variety of cellular biological processes can be affected by protein aggregates that consume essential factors necessary for maintaining proteostasis, which leads to the proteostasis imbalance and further accumulation of protein aggregates, often resulting in age-related neurodegenerative disease progression and aging. However, in addition to their well-established pathological effects, amyloids also play various physiological roles, and many important biological processes involve such 'functional amyloids'. This chapter represents a brief overview of the protein aggregation phenomenon outlines a timeline provides of some key discoveries in this exciting field.


Assuntos
Agregados Proteicos , Humanos , Animais , Amiloide/metabolismo , Amiloide/química , Agregação Patológica de Proteínas/metabolismo , Dobramento de Proteína , Proteínas/metabolismo , Proteínas/química
18.
Prog Mol Biol Transl Sci ; 206: 11-54, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38811078

RESUMO

The main cause of many neurodegenerative diseases and systemic amyloidoses is protein and peptide aggregation and the formation of amyloid fibrils. The study of aggregation mechanisms, the discovery and description of aggregate structures, and a comprehensive understanding of the molecular mechanisms of amyloid formation are of great importance for the diagnostic processes at the molecular level and for the development of therapeutic strategies to counter aggregation-associated disorders. Given that understanding protein misfolding phenomena is directly related to the protein folding process, we will briefly explain the protein folding mechanism and then discuss the important factors involved in protein aggregation. In the following, we review different mechanisms of amyloid formation and finally represent the current knowledge on how amyloid fibrils are formed based on kinetic and thermodynamic factors.


Assuntos
Amiloide , Agregados Proteicos , Amiloide/metabolismo , Amiloide/química , Humanos , Animais , Dobramento de Proteína , Cinética , Termodinâmica , Agregação Patológica de Proteínas/metabolismo
19.
Prog Mol Biol Transl Sci ; 206: 435-472, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38811087

RESUMO

Protein aggregates and amyloid fibrils have special qualities and are used in a variety of biotechnological applications. They are extensively employed in bioremediation, biomaterials, and biocatalysis. Because of their capacity to encapsulate and release pharmaceuticals and their sensitivity to certain molecules, respectively, they are also used in drug delivery and biosensor applications. They have also demonstrated potential in the domains of food and bioremediation. Additionally, amyloid peptides have drawn interest in biological applications, especially in the investigation of illnesses like Parkinson's and Alzheimer's. The unique characteristics of amyloid fibrils, namely their mechanical strength and ß-sheet structure, make them adaptable to a wide range of biotechnological uses. Even with their promise, one important factor to keep in mind before widely using modified amyloid materials is their potential toxicity. Thus, current research aims to overcome safety concerns while maximizing their potential.


Assuntos
Amiloide , Biotecnologia , Amiloide/química , Amiloide/metabolismo , Humanos , Animais
20.
Prog Mol Biol Transl Sci ; 206: 85-109, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38811090

RESUMO

In vivo, protein aggregation arises due to incorrect folding or misfolding. The aggregation of proteins into amyloid fibrils is the characteristic feature of various misfolding diseases known as amyloidosis, such as Alzheimer's and Parkinson's disease. The heterogeneous nature of these fibrils restricts the extent to which their structure may be characterized. Advancements in techniques, such as X-ray diffraction, cryo-electron microscopy, and solid-state NMR have yielded intricate insights into structures of different amyloid fibrils. These studies have unveiled a diverse range of polymorphic structures that typically conform to the cross-ß amyloid pattern. This chapter provides a concise overview of the information acquired in the field of protein aggregation, with particular focus on amyloids.


Assuntos
Amiloide , Humanos , Amiloide/química , Amiloide/metabolismo , Amiloide/ultraestrutura , Animais , Agregados Proteicos
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