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International Journal of Molecular... Feb 2023Amyloidosis refers to a clinically heterogeneous group of disorders characterized by the extracellular deposition of amyloid proteins in various tissues of the body. To... (Review)
Review
Amyloidosis refers to a clinically heterogeneous group of disorders characterized by the extracellular deposition of amyloid proteins in various tissues of the body. To date, 42 different amyloid proteins that originate from normal precursor proteins and are associated with distinct clinical forms of amyloidosis have been described. Identification of the amyloid type is essential in clinical practice, since prognosis and treatment regimens both vary according to the particular amyloid disease. However, typing of amyloid protein is often challenging, especially in the two most common forms of amyloidosis, i.e., the immunoglobulin light chain amyloidosis and transthyretin amyloidosis. Diagnostic methodology is based on tissue examinations as well as on noninvasive techniques including serological and imaging studies. Tissue examinations vary depending on the tissue preparation mode, i.e., whether it is fresh-frozen or fixed, and they can be carried out by ample methodologies including immunohistochemistry, immunofluorescence, immunoelectron microscopy, Western blotting, and proteomic analysis. In this review, we summarize current methodological approaches used for the diagnosis of amyloidosis and discusses their utility, advantages, and limitations. Special attention is paid to the simplicity of the procedures and their availability in clinical diagnostic laboratories. Finally, we describe new methods recently developed by our team to overcome limitations existing in the standard assays used in common practice.
Topics: Humans; Immunoglobulin Light-chain Amyloidosis; Proteomics; Amyloid; Amyloid Neuropathies, Familial; Amyloidogenic Proteins
PubMed: 36902083
DOI: 10.3390/ijms24054655 -
Communications Biology Nov 2022Structural investigations of amyloid fibrils often rely on heterologous bacterial overexpression of the protein of interest. Due to their inherent hydrophobicity and...
Structural investigations of amyloid fibrils often rely on heterologous bacterial overexpression of the protein of interest. Due to their inherent hydrophobicity and tendency to aggregate as inclusion bodies, many amyloid proteins are challenging to express in bacterial systems. Cell-free protein expression is a promising alternative to classical bacterial expression to produce hydrophobic proteins and introduce NMR-active isotopes that can improve and speed up the NMR analysis. Here we implement the cell-free synthesis of the functional amyloid prion HET-s(218-289). We present an interesting case where HET-s(218-289) directly assembles into infectious fibril in the cell-free expression mixture without the requirement of denaturation procedures and purification. By introducing tailored C and N isotopes or CF and CHF labels at strategic amino-acid positions, we demonstrate that cell-free synthesized amyloid fibrils are readily amenable to high-resolution magic-angle spinning NMR at sub-milligram quantity.
Topics: Amyloid; Prions; Magnetic Resonance Spectroscopy; Amyloidogenic Proteins; Magnetic Resonance Imaging
PubMed: 36352173
DOI: 10.1038/s42003-022-04175-1 -
Biomolecules Nov 2022Damage or loss of brain cells and impaired neurochemistry, neurogenesis, and synaptic and nonsynaptic plasticity of the brain lead to dementia in neurodegenerative... (Review)
Review
Damage or loss of brain cells and impaired neurochemistry, neurogenesis, and synaptic and nonsynaptic plasticity of the brain lead to dementia in neurodegenerative diseases, such as Alzheimer's disease (AD). Injury to synapses and neurons and accumulation of extracellular amyloid plaques and intracellular neurofibrillary tangles are considered the main morphological and neuropathological features of AD. Age, genetic and epigenetic factors, environmental stressors, and lifestyle contribute to the risk of AD onset and progression. These risk factors are associated with structural and functional changes in the brain, leading to cognitive decline. Biomarkers of AD reflect or cause specific changes in brain function, especially changes in pathways associated with neurotransmission, neuroinflammation, bioenergetics, apoptosis, and oxidative and nitrosative stress. Even in the initial stages, AD is associated with Aβ neurotoxicity, mitochondrial dysfunction, and tau neurotoxicity. The integrative amyloid-tau-mitochondrial hypothesis assumes that the primary cause of AD is the neurotoxicity of Aβ oligomers and tau oligomers, mitochondrial dysfunction, and their mutual synergy. For the development of new efficient AD drugs, targeting the elimination of neurotoxicity, mutual potentiation of effects, and unwanted protein interactions of risk factors and biomarkers (mainly Aβ oligomers, tau oligomers, and mitochondrial dysfunction) in the early stage of the disease seems promising.
Topics: Humans; Alzheimer Disease; Amyloid beta-Peptides; Amyloid; Amyloidogenic Proteins; Mitochondria
PubMed: 36421690
DOI: 10.3390/biom12111676 -
Current Issues in Molecular Biology 2020Post-translational modifications (PTMs) play important roles in altering the structure and function of proteins. In this article, we focus on ubiquitination and... (Review)
Review
Post-translational modifications (PTMs) play important roles in altering the structure and function of proteins. In this article, we focus on ubiquitination and SUMOylation of amyloidogenic proteins. We discuss the functional contributions of PTMs on proteins involved in amyloid-related diseases as well as the aberrant PTM signatures of the disease agents. In addition, we extend our discussion to the nascent field of functional amyloids, a subclass of amyloids that perform physiological functions. Here, we present examples from mammals and yeast to gain insight into physiological regulation of amyloid-like proteins.
Topics: Alzheimer Disease; Amyloidogenic Proteins; Amyotrophic Lateral Sclerosis; Animals; Humans; Peptides; Prions; Protein Processing, Post-Translational; Sumoylation; Superoxide Dismutase-1; Synucleinopathies; Ubiquitination; Yeasts; tau Proteins
PubMed: 31422940
DOI: 10.21775/cimb.035.195 -
Biomolecules Jul 2021Aberrant protein folding underpins many neurodegenerative diseases as well as certain myopathies and cancers. Protein misfolding can be driven by the presence of... (Review)
Review
Aberrant protein folding underpins many neurodegenerative diseases as well as certain myopathies and cancers. Protein misfolding can be driven by the presence of distinctive prion and prion-like regions within certain proteins. These prion and prion-like regions have also been found to drive liquid-liquid phase separation. Liquid-liquid phase separation is thought to be an important physiological process, but one that is prone to malfunction. Thus, aberrant liquid-to-solid phase transitions may drive protein aggregation and fibrillization, which could give rise to pathological inclusions. Here, we review prions and prion-like proteins, their roles in phase separation and disease, as well as potential therapeutic approaches to counter aberrant phase transitions.
Topics: Amyloidogenic Proteins; Humans; Molecular Chaperones; Neurodegenerative Diseases; Phase Transition; Prion Proteins; Protein Domains; Protein Folding; RNA
PubMed: 34356638
DOI: 10.3390/biom11071014 -
Journal of the American Chemical Society May 2022SARS-CoV-2 infection is associated with a surprising number of morbidities. Uncanny similarities with amyloid-disease associated blood coagulation and fibrinolytic...
SARS-CoV-2 infection is associated with a surprising number of morbidities. Uncanny similarities with amyloid-disease associated blood coagulation and fibrinolytic disturbances together with neurologic and cardiac problems led us to investigate the amyloidogenicity of the SARS-CoV-2 spike protein (S-protein). Amyloid fibril assays of peptide library mixtures and theoretical predictions identified seven amyloidogenic sequences within the S-protein. All seven peptides in isolation formed aggregates during incubation at 37 °C. Three 20-amino acid long synthetic spike peptides (sequence 192-211, 601-620, 1166-1185) fulfilled three amyloid fibril criteria: nucleation dependent polymerization kinetics by ThT, Congo red positivity, and ultrastructural fibrillar morphology. Full-length folded S-protein did not form amyloid fibrils, but amyloid-like fibrils with evident branching were formed during 24 h of S-protein coincubation with the protease neutrophil elastase (NE) . NE efficiently cleaved S-protein, rendering exposure of amyloidogenic segments and accumulation of the amyloidogenic peptide 194-203, part of the most amyloidogenic synthetic spike peptide. NE is overexpressed at inflamed sites of viral infection. Our data propose a molecular mechanism for potential amyloidogenesis of SARS-CoV-2 S-protein in humans facilitated by endoproteolysis. The prospective of S-protein amyloidogenesis in COVID-19 disease associated pathogenesis can be important in understanding the disease and long COVID-19.
Topics: Amino Acid Sequence; Amyloid; Amyloidogenic Proteins; COVID-19; Humans; Leukocyte Elastase; Peptides; Prospective Studies; Protein Structure, Secondary; SARS-CoV-2; Spike Glycoprotein, Coronavirus; Post-Acute COVID-19 Syndrome
PubMed: 35579205
DOI: 10.1021/jacs.2c03925 -
International Journal of Molecular... Aug 2023Amyloid aggregates are diverse proteinaceous assemblies, including one or more protein species, wherein the molecules interact according to characteristic patterns [...].
Amyloid aggregates are diverse proteinaceous assemblies, including one or more protein species, wherein the molecules interact according to characteristic patterns [...].
Topics: Amyloidogenic Proteins
PubMed: 37686116
DOI: 10.3390/ijms241713310 -
Cold Spring Harbor Perspectives in... Jun 2017The ability of normally soluble proteins to convert into amyloid fibrils is now recognized to be a generic phenomenon. The overall cross-β architecture of the core... (Review)
Review
The ability of normally soluble proteins to convert into amyloid fibrils is now recognized to be a generic phenomenon. The overall cross-β architecture of the core elements of such structures is closely similar for different amino acid sequences, as this architecture is dominated by interactions associated with the common polypeptide main chain. In contrast, the multiplicity of complex and intricate structures of the functional states of proteins is dictated by specific interactions involving the variable side chains, the sequence of which is unique to a given protein. Nevertheless, the side chains dictate important aspects of the amyloid structure, including the regions of the sequence that form the core elements of the fibrils and the kinetics and mechanism of the conversion process. The formation of the amyloid state of proteins is of particular importance in the context of a range of medical disorders that include Alzheimer's and Parkinson's diseases and type 2 diabetes. These disorders are becoming increasingly common in the modern world, primarily as a consequence of increasing life spans and changing lifestyles, and now affect some 500 million people worldwide. This review describes recent progress in our understanding of the molecular origins of these conditions and discusses emerging ideas for new and rational therapeutic strategies by which to combat their onset and progression.
Topics: Alzheimer Disease; Amino Acids; Amyloid beta-Peptides; Amyloidogenic Proteins; Diabetes Mellitus, Type 2; Disease Progression; Homeostasis; Humans; Kinetics; Microscopy, Atomic Force; Molecular Chaperones; Mutation; Parkinson Disease; Peptides; Protein Binding; Protein Denaturation; Protein Domains; Protein Folding; src Homology Domains
PubMed: 28062560
DOI: 10.1101/cshperspect.a023648 -
The FEBS Journal Aug 2020Mitochondria are key organelles, which maintain energy metabolism and cellular homeostasis. Mitochondria support transcriptional regulation and proteostatic signaling... (Review)
Review
Mitochondria are key organelles, which maintain energy metabolism and cellular homeostasis. Mitochondria support transcriptional regulation and proteostatic signaling mechanisms through crosstalk between the mitochondria itself, the nucleus, and the cytoplasm. Mitochondrial dysfunction leads to impaired proteostasis, and both are key pathological features of age-related neurological disorders. For example, Alzheimer's and Parkinson's diseases feature mitochondrial-targeted protein aggregates and impaired mitochondrial function, although the mechanistic causes are poorly understood. Vascular abnormalities and hypometabolism in such neurological diseases are reported several years before key clinical disease symptoms even become apparent. Recent investigations suggest that processing of such aggregates within mitochondria can offer protective functions, specifically by restoring energy (ATP) in starving cells. We hypothesize that the accumulation of protein aggregates in mitochondria can not only disrupt its functions, but also render a protective role to fulfill energy demands in hypometabolic conditions. Growing evidence favors mitochondrial defense to toxic amyloid aggregates/oligomers as a protective response. In this viewpoint article, we will present several publications (in addition to our own) that serve to connect the possible role of protein aggregates in mitochondrial energy production for degenerative conditions.
Topics: Amyloidogenic Proteins; Animals; Brain; Energy Metabolism; Humans; Mitochondria; Protein Aggregates; Protein Aggregation, Pathological; Proteostasis; Signal Transduction
PubMed: 31981301
DOI: 10.1111/febs.15225 -
Expert Review of Vaccines 2016Alzheimer's disease (AD) is the most common form of dementia worldwide. It is characterized by an imbalance between the production and clearance of amyloid β (Aβ) and... (Review)
Review
Alzheimer's disease (AD) is the most common form of dementia worldwide. It is characterized by an imbalance between the production and clearance of amyloid β (Aβ) and tau proteins. In AD these normal proteins accumulate, leading to aggregation and a conformational change forming oligomeric and fibrillary species with a high β-sheet content. Active and passive immunotherapeutic approaches result in dramatic reduction of Aβ pathology in AD animal models. However, there is much more limited evidence in human studies of significant clinical benefits from these strategies and it is becoming apparent that they may only be effective very early in AD. Vaccination targeting only tau pathology has shown benefits in some mouse studies but human studies are limited. Greater therapeutic efficacy for the next generation of vaccine approaches will likely benefit from specifically targeting the most toxic species of Aβ and tau, ideally simultaneously.
Topics: Alzheimer Disease; Amyloidogenic Proteins; Animals; Disease Models, Animal; Humans; Vaccines
PubMed: 26577574
DOI: 10.1586/14760584.2016.1121815