Search Results (23)

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder characterized by memory loss and cognitive decline. Its main pathological features are extracellular plaques composed of aggregated amyloid-β (Aβ) peptides and intracellular neurofibrillary tangles formed by hyperphosphorylated tau. The Aβ hypothesis proposes that Aβ accumulation is a key driver of AD, influencing tau pathology, neuroinflammation, and neurodegeneration. However, therapies that reduce Aβ have shown limited clinical benefits. This suggests that the mechanisms underlying peptide-mediated modulation of AD pathology are much more complex. Both Aβ and tau undergo various post-translational modifications (PTMs) that affect their structure, aggregation, and toxicity. In addition, these abnormal proteins are not efficiently cleared in AD, indicating dysfunction of the protein quality control (PQC) system that maintains proteostasis. Such abnormal PTMs and impaired PQC likely work together to drive disease progression, which may explain the limited success of Aβ-reduction therapies. In this review, we describe how major PTMs, including phosphorylation, ubiquitination, acetylation, glycosylation, and oxidation, regulate the pathological behavior of Aβ and tau. We also discuss the role of the PQC systems in the pathology of AD. We propose that dysregulation of PTMs and PQC constitutes a convergent mechanism underlying AD pathogenesis. Therapeutic strategies targeting these processes may provide more effective and sustained disease modification than approaches focused solely on Aβ reduction. Full article

The formation of hemoglobin (Hb) and myoglobin (Mb) supramolecular complexes is examined. These key proteins for oxygen transport and storage undergo conformational transitions, some of which are induced by stress factors, particularly redox-active and toxic substances, e.g., reactive oxygen species (ROS) and reactive carbonyl compounds (RCC). These modifications can lead to partial denaturation, exposure of hydrophobic regions, and loss of stability, promoting self-assembly into high-molecular structures. Reversible associations serve regulatory roles: protein stabilization, transient functional inactivation, and generation of biological signals. Irreversible associations result in the formation of stable aggregates constituting pathological hallmarks of amyloidosis and other proteopathies. Although Hb and Mb fibrillization is not part of their physiological function, under oxidative stress, altered pH, high temperatures, or the presence of post-translational modifications, they can adopt amyloid-like structures characterized by cross-β conformation. Such aggregates exhibit high resistance to proteolysis and accumulate in tissues. Understanding molecular mechanisms behind Hb and Mb aggregation is critical for the diagnosis and timely therapy of amyloid-related diseases. The stability, regular structure, and biocompatibility of Hb and Mb fibrils make them promising for biomedical applications. Functional nanomaterials based on these fibrils are being developed for high-sensitivity biosensors, bioelectronic devices, and nanocarriers for targeted drug delivery. Full article

Alzheimer’s disease (AD) is the most prevalent cause of dementia, characterized by progressive cognitive decline, amyloid-β (Aβ) plaques, and neurofibrillary tangles composed of hyperphosphorylated tau protein. Other tauopathies, including frontotemporal lobar degeneration (FTLD), progressive supranuclear palsy (PSP), and corticobasal degeneration (CBD) share pathological hallmarks centered on abnormal tau biology. Increasing evidence highlights the role of post-translational modifications in modulating these pathogenic processes. Among these, glycosylation, the enzymatic attachment of glycans to proteins or lipids, has emerged as a critical regulator of protein folding, trafficking, aggregation, and clearance. Both N-linked glycosylation (N-glycosylation) and O-linked glycosylation (O-glycosylation) influence tau stability, Aβ processing, receptor signaling, synaptic integrity, and neuroinflammation. Dysregulated glycosylation patterns have been documented in brains and cerebrospinal fluid (CSF) of AD patients, suggesting biomarker potential and novel therapeutic targets. Moreover, glycosyltransferases and glycosidases show altered expression in neurodegeneration, linking metabolic and inflammatory pathways to tauopathy progression. This review synthesizes current evidence on the implications and consequences of glycosylation in AD and other tauopathies, integrating mechanistic, pathological, and clinical findings. We also discuss advances in glycoproteomics, the interplay between glycosylation and phosphorylation, and the translational potential of targeting glycosylation pathways for diagnosis and therapy. Full article

Alzheimer’s disease is driven by multiple molecular drivers, including the pathological behavior of two intrinsically disordered proteins, amyloid-β (Aβ) and tau, whose aggregation is regulated by sequence-encoded ensembles and liquid–liquid phase separation (LLPS). This review integrates recent advances in biophysics, structural biology, and computational modeling to provide a multiscale perspective on how sequence determinants, post-translational modifications, and protein dynamics regulate the conformational landscapes of Aβ and tau. We discuss sequence-to-ensemble principles, from charge patterning and aromatic binders to familial mutations that reprogram structural ensembles and modulate LLPS. Structural studies, including NMR, SAXS, cryo-EM, and cryo-electron tomography, trace transitions from disordered monomers to fibrils and tissue-level structures. We highlight experimental challenges in LLPS assays, emerging standards for reproducibility, e.g., LLPSDB, PhaSePro, and FUS benchmarks, and computational strategies to refine and condensate modeling. Finally, we explore the therapeutic implications, including condensate-aware medicinal chemistry, ensemble-driven docking, and novel insights from clinical trials of anti-Aβ antibodies. Together, these perspectives underscore a paradigm shift toward environment- and ensemble-aware therapeutic design for Alzheimer’s and related protein condensation disorders. Full article

The islet amyloid polypeptide (IAPP) is a 37-residue peptide hormone secreted by pancreatic β-cells that is known to aggregate into amyloid fibrils. These fibrils accumulate in the pancreatic islets of individuals afflicted with type 2 diabetes and are implicated in β-cell dysfunction. Metal ions such as copper and zinc are known to modulate IAPP fibrillization, yet the role of metal-induced oxidative modifications in this process remains largely unexplored. This study examines the non-enzymatic post-translational oxidation of IAPP and its effects on aggregation using the biologically relevant Cu/O₂/ascorbate system. Mass spectrometry identified residues within the amyloidogenic region (residues 20–29) as the primary targets of oxidation. These oxidative modifications impaired the formation of cross-β-sheet amyloid fibrils and promoted the accumulation of amorphous aggregates. The H18A IAPP derivative, lacking the key metal-binding histidine, was also examined to assess the impact of sequence variation on oxidation and aggregation. Copper-mediated oxidation of H18A resulted in a broader distribution of oxidation sites and impacts fibril formation. These findings provide preliminary mechanistic insights into copper-induced oxidation and its impact on IAPP aggregation pathways. Full article

Alzheimer’s disease (AD), a predominant neurodegenerative disorder, is clinically characterized by progressive cognitive deterioration and behavioral deficits. An in-depth understanding of the pathogenesis and neuropathology of AD is essential for the development of effective treatments and early diagnosis techniques. The neuropathological signature of AD involves two hallmark lesions: intraneuronal neurofibrillary tangles composed of hyperphosphorylated tau aggregates and extracellular senile plaques containing amyloid-β (Aβ) peptide depositions. Although Aβ-centric research has dominated AD investigations over the past three decades, pharmacological interventions targeting Aβ pathology have failed to demonstrate clinical efficacy. Tau, a microtubule-associated protein predominantly localized to neuronal axons, orchestrates microtubule stabilization and axonal transport through dynamic tubulin interactions under physiological conditions. In AD pathogenesis, however, tau undergoes pathogenic post-translational modifications (PTMs), encompassing hyperphosphorylation, lysine acetylation, methylation, ubiquitination, and glycosylation. These PTM-driven alterations induce microtubule network disintegration, mitochondrial dysfunction, synaptic impairment, and neuroinflammatory cascades, ultimately culminating in irreversible neurodegeneration and progressive cognitive decline. This review synthesizes contemporary advances in tau PTM research and delineates their mechanistic contributions to AD pathogenesis, thereby establishing a framework for biomarker discovery, targeted therapeutic development, and precision medicine approaches in tauopathies. This review synthesizes contemporary advances in tau PTM research and delineates their mechanistic contributions to AD pathogenesis, thereby establishing a solid theoretical and experimental basis for the early diagnosis of neurodegenerative diseases, the discovery of therapeutic targets, and the development of novel therapeutic strategies. Full article

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder, heterogeneous at the molecular level and characterized by diverse and complex pathological features. Such features are known to accumulate silently in the brain over years or even decades before the onset of detectable symptoms. Despite long years of intense research activities, the disease remains orphaned of either disease-modifying therapies or a specific blood test capable of predicting the disease in the pre-symptomatic stages. This disappointing outcome of such efforts can be attributed to a number of factors. One of these factors is the failure of earlier research to capture the heterogeneity of the disease. Such failure has the direct consequence of poor patient stratification, which in turn impacts negatively on the development of specific and effective therapy. The second factor is the absence of detailed and accurate information on proteins and associated post-translational modifications, which may influence the initiation and progress of the disease. Recent studies have demonstrated that the quantification of various isoforms of phosphorylated tau protein in plasma and other biofluids can be considered as potential biomarkers for the early detection of Alzheimer’s disease. Mass spectrometry-based proteomics and immunoassay-based multiplex proteomics are the two technologies in current use for probing the human proteome, both in tissues and biofluids. In the present review, we discuss the contribution of MS-based proteomics to efforts aimed at the identification and eventual characterization of the heterogeneity of the disease, and the key role of the same technique in the analysis of protein post-translational modifications associated with the disease is also discussed. Full article

Soluble oligomeric forms of Amyloid-β (Aβ) are considered the major toxic species leading to the neurodegeneration underlying Alzheimer’s disease (AD). Therefore, drugs that prevent oligomer formation might be promising. The atypical dipeptide GAL-201 is orally bioavailable and interferes as a modulator of Aβ aggregation. It binds to aggregation-prone, misfolded Aβ monomers with high selectivity and affinity, thereby preventing the formation of toxic oligomers. Here, we demonstrate that the previously observed protective effect of GAL-201 on synaptic plasticity occurs irrespective of shortages and post-translational modifications (tested isoforms: Aβ_1–42, Aβ(p3-42), Aβ_1–40 and 3NTyr(10)-Aβ). Interestingly, the neuroprotective activity of a single dose of GAL-201 was still present after one week and correlated with a prevention of Aβ-induced spine loss. Furthermore, we could observe beneficial effects on spine morphology as well as the significantly reduced activation of proinflammatory microglia and astrocytes in the presence of an Aβ_1–42-derived toxicity. In line with these in vitro data, GAL-201 additionally improved hippocampus-dependent spatial learning in the “tgArcSwe” AD mouse model after a single subcutaneous administration. By this means, we observed changes in the deposition pattern: through the clustering of misfolded monomers as off-pathway non-toxic Aβ agglomerates, toxic oligomers are removed. Our results are in line with previously collected preclinical data and warrant the initiation of Investigational New Drug (IND)-enabling studies for GAL-201. By demonstrating the highly efficient detoxification of β-sheet monomers, leading to the neutralization of Aβ oligomer toxicity, GAL-201 represents a promising drug candidate against Aβ-derived pathophysiology present in AD. Full article

Amyloid β protein (Aβ) deposition has been implicated as the molecular driver of Alzheimer’s disease (AD) progression. The modulation of the formation of abnormal aggregates and their post-translational modification is strongly suggested as the most effective approach to anti-AD. Beta-site APP-cleaving enzyme 1 (BACE1) acts upstream in amyloidogenic processing to generate Aβ, which rapidly aggregates alone or in combination with acetylcholinesterase (AChE) to form fibrils. Accumulated Aβ promotes BACE1 activation via glycogen synthase kinase-3β (GSK-3β) and is post-translationally modified by glutaminyl cyclase (QC), resulting in increased neurotoxicity. A novel multi-target inhibitor as a potential AD agent was identified using an in silico approach and experimental validation. Magnolia officinalis, which showed the best anti-AD activity in our preliminary study, was subjected to analysis, and 82 compounds were studied. Among 23 compounds with drug-likeness, blood–brain barrier penetration, and safety, honokiol emerged as a lead structure for the inhibition of BACE1, AChE, QC, and GSK-3β in docking and molecular dynamics (MD) simulations. Furthermore, honokiol was found to be an excellent multi-target inhibitor of these enzymes with an IC₅₀ of 6–90 μM, even when compared to other natural single-target inhibitors. Taken together, the present study is the first to demonstrate that honokiol acts as a multiple enzyme inhibitor with an excellent pharmacokinetic and safety profile which may provide inhibitory effects in broad-range areas including the overproduction, aggregation, and post-translational modification of Aβ. It also provides insight into novel structural features for the design and discovery of multi-target inhibitors for anti-AD. Full article

Alzheimer’s disease (AD) is associated with the accumulation of β-amyloids (Aβs) and the formation of Aβ plaques in the brain. Various structural forms and isoforms of Aβs that have variable propensities for oligomerization and toxicity and may differentially affect the development of AD have been identified. In addition, there is evidence that β-amyloids are engaged in complex interactions with the innate and adaptive immune systems, both of which may also play a role in the regulation of AD onset and progression. In this review, we discuss what is currently known about the intricate interplay between β-amyloids and the immune response to Aβs with a more in-depth focus on the possible roles of B cells in the pathogenesis of AD. Full article

A Disintegrin and Metalloprotease 10, also known as ADAM10, is a cell surface protease ubiquitously expressed in mammalian cells where it cuts several membrane proteins implicated in multiple physiological processes. The dysregulation of ADAM10 expression and function has been implicated in pathological conditions, including Alzheimer’s disease (AD). Although it has been suggested that ADAM10 is expressed as a zymogen and the removal of the prodomain results in its activation, other potential mechanisms for the ADAM10 proteolytic function and activation remain unclear. Another suggested mechanism is post-translational modification of the cytoplasmic domain, which regulates ADAM10-dependent protein ectodomain shedding. Therefore, the precise and temporal activation of ADAM10 is highly desirable to reveal the fine details of ADAM10-mediated cleavage mechanisms and protease-dependent therapeutic applications. Here, we present a strategy to control prodomain and cytosolic tail cleavage to regulate ADAM10 shedding activity without the intervention of small endogenous molecule signaling pathways. We generated a series of engineered ADAM10 analogs containing Tobacco Etch Virus protease (TEV) cleavage site (TEVcs), rendering ADAM10 cleavable by TEV. This strategy revealed that, in the absence of other stimuli, the TEV-mediated removal of the prodomain could not activate ADAM10. However, the TEV-mediated cleavage of the cytosolic domain significantly increased ADAM10 activity. Then, we generated ADAM10 with a minimal constitutively catalytic activity that increased significantly in the presence of TEV or after activating a chemically activatable TEV. Our results revealed a bioengineering strategy for controlling the ADAM10 activity in living cells, paving the way to obtain spatiotemporal control of ADAM10. Finally, we proved that our approach of controlling ADAM10 promoted α-secretase activity and the non-amyloidogenic cleavage of amyloid-β precursor protein (APP), thereby increasing the production of the neuroprotective soluble ectodomain (sAPPα). Our bioengineering strategy has the potential to be exploited as a next-generation gene therapy for AD. Full article

Amyloidoses are a group of diseases associated with deposits of amyloid fibrils in different tissues. So far, 36 different types of amyloidosis are known, each due to the misfolding and accumulation of a specific protein. Amyloid deposits can be found in several organs, including the heart, brain, kidneys, and spleen, and can affect single or multiple organs. Generally, amyloid-forming proteins become prone to aggregate due to genetic mutations, acquired environmental factors, excessive concentration, or post-translational modifications. Interestingly, amyloid aggregates are often composed of proteolytic fragments, derived from the degradation of precursor proteins by yet unidentified proteases, which display higher amyloidogenic tendency compared to precursor proteins, thus representing an important mechanism in the onset of amyloid-based diseases. In the present review, we summarize the current knowledge on the proteolytic susceptibility of three of the main human amyloidogenic proteins, i.e., transthyretin, β-amyloid precursor protein, and α-synuclein, in the onset of amyloidosis. We also highlight the role that proteolytic enzymes can play in the crosstalk between intestinal inflammation and amyloid-based diseases. Full article

The study of the molecular mechanisms of the pathogenesis of Alzheimer’s disease (AD) is extremely important for identifying potential therapeutic targets as well as early markers. In this regard, the study of the role of post-translational modifications (PTMs) of β-amyloid (Aβ) peptides is of particular relevance. Serine-8 phosphorylated forms (pSer8-Aβ) have been shown to have an increased aggregation capacity and may reflect the severity of amyloidosis. Here, an approach for quantitative assessment of pSer8-Aβ based on matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is proposed. The relative fraction of pSer8-Aβ was estimated in the total Aβ-pool with a detection limit of 1 fmol for pSer8-Aβ (1–16) and an accuracy of 2% for measurements in the reflectron mode. The sensitivity of the developed method is suitable for determining the proportion of phosphorylated peptides in biological samples. Full article

Type-1-diabetes (T1D) is a multifactorial disorder with a global incidence of about 8.4 million individuals in 2021. It is primarily classified as an autoimmune disorder, where the pancreatic β-cells are unable to secrete sufficient insulin. This leads to elevated blood glucose levels (hyperglycemia). The development of T1D is an intricate interplay between various risk factors, such as genetic, environmental, and cellular elements. In this review, we focus on the cellular elements, such as ER (endoplasmic reticulum) stress and its consequences for T1D pathogenesis. One of the major repercussions of ER stress is defective protein processing. A well-studied example is that of islet amyloid polypeptide (IAPP), which is known to form cytotoxic amyloid plaques when misfolded. This review discusses the possible association between ER stress, IAPP, and amyloid formation in β-cells and its consequences in T1D. Additionally, ER stress also leads to autoantigen generation. This is driven by the loss of Ca⁺⁺ ion homeostasis. Imbalanced Ca⁺⁺ levels lead to abnormal activation of enzymes, causing post-translational modification of β-cell proteins. These modified proteins act as autoantigens and trigger the autoimmune response seen in T1D islets. Several of these autoantigens are also crucial for insulin granule biogenesis, processing, and release. Here, we explore the possible associations between ER stress leading to defects in insulin secretion and ultimately β-cell destruction. Full article

Alzheimer’s disease (AD) is the leading cause of dementia among the elderly. Neuropathologically, AD is characterized by the deposition of a 39- to 42-amino acid long β-amyloid (Aβ) peptide in the form of senile plaques. Several post-translational modifications (PTMs) in the N-terminal domain have been shown to increase the aggregation and cytotoxicity of Aβ, and specific Aβ proteoforms (e.g., Aβ with isomerized D7 (isoD7-Aβ)) are abundant in the senile plaques of AD patients. Animal models are indispensable tools for the study of disease pathogenesis, as well as preclinical testing. In the presented work, the accumulation dynamics of Aβ proteoforms in the brain of one of the most widely used amyloid-based mouse models (the 5xFAD line) was monitored. Mass spectrometry (MS) approaches, based on ion mobility separation and the characteristic fragment ion formation, were applied. The results indicated a gradual increase in the Aβ fraction of isoD7-Aβ, starting from approximately 8% at 7 months to approximately 30% by 23 months of age. Other specific PTMs, in particular, pyroglutamylation, deamidation, and oxidation, as well as phosphorylation, were also monitored. The results for mice of different ages demonstrated that the accumulation of Aβ proteoforms correlate with the formation of Aβ deposits. Although the mouse model cannot be a complete analogue of the processes occurring in the human brain in AD, and several of the observed parameters differ significantly from human values supposedly due to the limited lifespan of the model animals, this dynamic study provides evidence on at least one of the possible mechanisms that can trigger amyloidosis in AD, i.e., the hypothesis on the relationship between the accumulation of isoD7-Aβ and the progression of AD-like pathology. Full article