Protein Misfolding and Aggregation in Proteinopathies: Causes, Mechanism and Cellular Response

Premature aging and metabolic diseases: the impact of telomere attrition

Driven by genetic and environmental factors, aging is a physiological process responsible for age-related degenerative changes in the body, cognitive decline, and impaired overall wellbeing. Notably, premature aging as well as the emergence of progeroid syndromes have posed concerns regarding chronic health conditions and comorbidities in the aging population. Accelerated telomere attrition is also implicated in metabolic dysfunction and the development of metabolic disorders. Impaired metabolic homeostasis arises secondary to age-related increases in the synthesis of free radicals, decreased oxidative capacity, impaired antioxidant defense, and disrupted energy metabolism. In particular, several cellular and molecular mechanisms of aging have been identified to decipher the influence of premature aging on metabolic diseases. These include defective DNA repair, telomere attrition, epigenetic alterations, and dysregulation of nutrient-sensing pathways. The role of telomere attrition premature aging in the pathogenesis of metabolic diseases has been largely attributed to pro-inflammatory states that promote telomere shortening, genetic mutations in the telomerase reverse transcriptase, epigenetic alteration, oxidative stress, and mitochondrial dysfunctions. Nonetheless, the therapeutic interventions focus on restoring the length of telomeres and may include treatment approaches to restore telomerase enzyme activity, promote alternative lengthening of telomeres, counter oxidative stress, and decrease the concentration of pro-inflammatory cytokines. Given the significance and robust potential of delaying telomere attrition in age-related metabolic diseases, this review aimed to explore the molecular and cellular mechanisms of aging underlying premature telomere attrition and metabolic diseases, assimilating evidence from both human and animal studies.

Advancements in Escherichia coli secretion systems for enhanced recombinant protein production

Escherichia coli is inarguably one of the most studied microorganisms across the spectrum of microbiology. It is very widely used in recombinant protein production owing to its rapid growth, ease of genetic manipulation, and relatively high protein yields. Despite all of its advantages, its inability to efficiently secrete proteins naturally remains a drawback leading to protein aggregation as inclusion bodies in the cytoplasm and consequent low overall protein yield. Therefore, many approaches to mitigate this weakness and enhance extracellular secretion to increase protein yield have been devised. This review explores the natural and engineered secretion systems in E. coli, highlighting their potential for enhanced protein secretion for non-glycosylated proteins. Natural one-step (e.g., Type I and III Secretion Systems) and two-step systems (e.g., Sec and Tat pathways) are detailed alongside recent advancements in genetic engineering, mutagenesis, and synthetic biology approaches aimed at improving protein yield, folding, and secretion efficiency. Emerging technologies, such as the ESETEC® and BacSec® platforms, promise scalable and cost-effective solutions for higher protein production. Challenges, including limited cellular capabilities and protein aggregation, are addressed through innovative strategies like cell wall modification, co-expression of chaperones, and medium optimization. This review emphasizes E. coli's adaptability to industrial applications, and the promising future of recombinant protein technologies.

Microbial signatures and therapeutic strategies in neurodegenerative diseases

Neurodegenerative diseases (NDs), including Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and multiple sclerosis (MS), arise from complex interactions between genetic factors, environmental exposures, and aging. Additionally, gut dysbiosis has been linked to systemic inflammation and neurodegeneration. Advances in microbiome and metabolome profiling techniques have provided deeper insights into how alterations in gut microbiota and dietary patterns affect metabolic pathways and contribute to the progression of NDs. This review explores the profiles of gut microbiome and metabolome derived biomarkers and their roles in NDs. Across phyla, families, and genera, we identified 55 microbial alterations in PD, 24 in AD, 4 in ALS, and 17 in MS. Some notable results include an increase in Akkermansia in PD, AD, and MS and a decrease in short-chain fatty acids (SCFAs) in PD and AD. We examined the effects of probiotics, prebiotics, fecal microbiota transplants (FMT), sleep, exercise, and diet on the microbiota, all of which contributed to delayed onset and alleviation of symptoms. Further, artificial intelligence (AI) and machine learning (ML) algorithms applied to omics data have been crucial in identifying novel therapeutic targets, diagnosing and predicting prognosis, and enabling personalized medicine using microbiota-modulating therapies in NDs patients.

Correlation of NADH/NAD+ electrochemical potential and enzymatic activity for investigating protein folding and kinetics

The biological activity of a protein is determined by its native three-dimensional structure. Various stress factors induce structural changes in the proteins that leads to altered protein homeostasis with the accumulation of misfolded and aggregated protein conformers. Standard methods such as spectrophotometry, luminometry and fluorimetry are conventionally used to study protein activity. Here, an electrochemical method has been developed to measure the change in anodic peak current (Ip,a) of NADH generated during the oxidation reaction. The method showed a linear range of detection from 62.5 μM to 1.0 mM (R2 = 0.999) for NADH with calculated detection limit of 16.02 μM and sensitivity of 1.75 × 103 μA mM-1 cm-2. The method was further employed to investigate the enzymatic activity and folding kinetics of malate dehydrogenase (MDH) and glucose-6-phosphate dehydrogenase (G6PDH). Also, the effect of aluminium ion (Al3+) on the activity and folding kinetics was investigated electrochemically. The Al3+ induced structural alterations in MDH and G6PDH were assessed using circular dichroism (CD), Thioflavin-T (ThT) and nuclear magnetic resonance (NMR). The developed label-free electrochemical method provides an alternative method for investigating protein activity and folding kinetics.

Peptide-Based Complex Coacervates Stabilized by Cation-π Interactions for Cell Engineering

Complex coacervation is a form of liquid-liquid phase separation, whereby two types of macromolecules, usually bearing opposite net charges, self-assemble into dense microdroplets driven by weak molecular interactions. Peptide-based coacervates have recently emerged as promising carriers to deliver large macromolecules (nucleic acids, proteins and complex thereof) inside cells. Thus, it is essential to understand their assembly/disassembly mechanisms at the molecular level in order to tune the thermodynamics of coacervates formation and the kinetics of cargo release upon entering the cell. In this study, we designed histidine-rich peptides consisting of modular sequences in which we systematically incorporate cationic, anionic, or aromatic residues at specific positions along the sequence in order to modulate intermolecular interactions and the resulting coacervation stability. We show that cation-π interactions between arginine and aromatic side chains are particularly efficient in stabilizing complex coacervates, and these interactions can be disrupted in the protein-rich intracellular environment, triggering the disassembly of complex coacervates followed by cargo release. With the additional grafting of a disulfide-based self-immolative side chain, these complex coacervates exhibited enhanced stability and could deliver proteins, mRNA, and CRISPR/Cas9 genome editing tools with tunable release kinetics into cells. This capability extends to challenging cell types, such as macrophages. Our study highlights the critical role of cation-π interactions in the design of peptide-based coacervates, expanding the biomedical and biotechnology potential of this emerging intracellular delivery platform.

Inhibition of Phosphorylated Alpha-Synuclein Aggregation by Synthetic Protein Mimetics and Foldamers

The formation of Lewy bodies (LB) is a pathological hallmark for synucleinopathies, which is an umbrella term for many diseases, including Parkinson's disease, Lewy body dementia, and multiple system atrophy. One of the main components of LB is the aggregates of phosphorylated modification of α-Synuclein at residue 129 (αS-129), a neuronal protein expressed in the dopaminergic neurons in the brain. There are equivocal results about the role of αS-129, suggesting its involvement in both potentiating pathology and a functional role to rescue pathology. Regardless, a potential therapeutic strategy for LB-based pathologies could be the identification of inhibitors of both αS and αS-129 aggregation. However, to the best of our knowledge, there are no reports of ligands that can potently inhibit the aggregation of αS-129. Our group has recently identified potent antagonists of αS aggregation based on the oligopyridylamide (synthetic protein mimetics) and oligoquinoline (foldamers) scaffolds. Both ligands were potent antagonists of αS aggregation-mediated disease phenotypes in various PD models. Here, we tested both ligands against αS-129 aggregation and the coaggregation of αS and αS-129 (αS/αS-129). Both ligands were potent antagonists of αS-129 aggregation and coaggregation of αS/αS-129 in biophysical and cellular models of PD. Both ligands rescued cell toxicity mediated by the coaggregation of αS/αS-129. To the best of our knowledge, these are the first ligands that potently inhibit the major component of LB. This finding will aid in the development of therapeutic insights into aggregation-related synucleinopathies.

Coomassie Brilliant Blue Induces Coiled-Coil Aggregation in Lysozyme at pH 7.4 by Hydrophobic and Electrostatic Forces

Several neurodegenerative diseases are associated with the deposition of amyloid fibrils. Although these diseases are irreversible, knowing the aggregation mechanism is useful in developing drugs that can arrest or decrease the aggregation rate. In this study, we are interested in investigating the effect of Coomassie brilliant blue (CBB G-250) on the aggregation of hen egg white lysozyme (HEWL) at pH 7.4. Various biophysical techniques have been used, such as turbidity, Rayleigh light scattering (RLS) kinetics, far-UV circular dichroism (CD), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) imaging. The turbidity data indicated that CBB (≥0.1 mM) induces aggregation in HEWL at pH 7.4. The aggregation kinetics caused by CBB are quick without a lag phase and are dependent on the CBB concentration. The far-UV CD data revealed that the CBB-induced aggregated samples had lost their CD signals without exhibiting a shift in the spectrum position. Sodium chloride and ammonium sulfate show little effect on the CBB-induced aggregates, but alcohol such as methanol, ethanol, and 2-propanol could reverse the aggregation. Overall, this study aims to better understand the mechanism underlying CBB-induced aggregation and keep in mind that CBB employed in laboratories can alter the protein structure. We report the aggregation of a natural protein due to coiled-coil formation induced by a dye at physiological pH and temperature conditions. This finding has high value because several dyes are used for diagnostic and therapeutic purposes, and coiled-coil formation is closely related to infection mechanisms and nanoparticle-based drug deliveries.

Multi-Site Red-Edge Excitation Shift Reveals the Residue-Specific Solvation Dynamics during the Native to Amyloid-like Transition of an Amyloidogenic Protein

Changes in water-protein interactions are crucial for proteins to achieve functional and nonfunctional conformations during structural transitions by modulating local stability. Amyloid-like protein aggregates in deteriorating neurons are hallmarks of neurodegenerative disorders. These aggregates form through significant structural changes, transitioning from functional native conformations to supramolecular cross-β-sheet structures via misfolded and oligomeric intermediates in a multistep process. However, the site-specific dynamics of water molecules from the native to misfolded conformations and further to oligomeric and compact amyloid structures remain poorly understood. In this study, we used the fluorescence method known as red-edge excitation shift (REES) to investigate the solvation dynamics at specific sites in various equilibrium conformations en route to the misfolding and aggregation of the functional domain of the TDP-43 protein (TDP-43tRRM). We generated three single tryptophan-single cysteine mutants of TDP-43tRRM, with the cysteines at different positions and tryptophan at a fixed position. Each sole cysteine was fluorescently labeled and used as a site-specific fluorophore along with the single tryptophan, creating four monitorable sites for REES studies. By investigating the site-specific extent of REES, we developed a residue-specific solvation dynamics map of TDP-43tRRM during its misfolding and aggregation. Our observations revealed that solvation dynamics progressively became more rigid and heterogeneous to varying extents at different sites during the transition from native to amyloid-like conformations.

Unraveling the Effects of Hexametaphosphate: Insights into Trypsin Aggregation and Structural Reversal

Elevated serum phosphate levels have been linked to increased mortality rates. This study investigated the effect of millimolar (mM) concentrations of sodium hexametaphosphate (SHMP) on trypsin's aggregation and structural stability at intestinal pH levels. We used various spectroscopic and microscopic techniques to investigate the structural changes of trypsin aggregates. Turbidity and light scattering results revealed that trypsin aggregates began to solubilize at SHMP concentrations above 1 mM, with maximum solubilization observed at 6 mM SHMP. Intrinsic, thioflavin T (ThT) fluorescence, and far-UV CD spectra indicated that trypsin amorphous aggregates turn into native-like structures in the presence of 6 mM SHMP. Transmission electron microscope (TEM) imaging also showed the disappearance of amorphous aggregates at higher SHMP concentrations. This study showed that higher SHMP concentrations solubilized the trypsin aggregates and induced a native-like conformation. These findings highlighted that SHMP could be a good protein aggregate solubilizer, with future applications in inclusion body solubilization and protein refolding.

Dog Aging: A Comprehensive Review of Molecular, Cellular, and Physiological Processes

The aging process is a multifactorial biological phenomenon starting at birth and persisting throughout life, characterized by a decline in physiological functions and adaptability. This decline results in the diminished capacity of aging organisms to respond to environmental changes and stressors, leading to reduced efficiency in metabolic, immune, and hormonal functions. As behavioral flexibility wanes, older individuals face longer recovery times and increased vulnerability to diseases. While early research proposed nine core hallmarks of mammalian aging, recent studies have expanded this framework to twelve key characteristics: epigenetic changes, genomic instability, telomere shortening, loss of proteostasis, altered metabolism, mitochondrial dysfunction, cellular senescence, disrupted intercellular communication, stem cell depletion, immune system dysfunction, accumulation of toxic metabolites, and dysbiosis. Given the growing interest in the aging area, we propose to add a new hallmark: impaired water homeostasis. This potential hallmark could play a critical role in aging processes and might open new directions for future research in the field. This review enhances our understanding of the physiological aspects of aging in dogs, suggesting new clinical intervention strategies to prevent and control issues that may arise from the pathological degeneration of these hallmarks.

Identification of a Hidden, Highly Aggregation-Prone Intermediate of Full-Length TDP-43 That Triggers its Misfolding and Amyloid Aggregation

In cells, TDP-43 is a crucial protein that can form harmful amyloid aggregates linked to fatal and incurable human neurodegenerative disorders. Normally, TDP-43 exists in a smaller soluble native state that prevents aggregation. However, aging and stress can destabilize this native state, leading to the formation of disease-causing amyloid aggregates via the formation of partially unfolded, high-energy intermediates with a greater tendency to aggregate. These intermediates are crucial in the early stages of amyloid formation and are challenging to study due to their low stability. Understanding the structure of these early aggregation-prone states of TDP-43 is essential for designing effective treatments for TDP-43 proteinopathies. Targeting these initial intermediates could be more effective than focusing on fully formed amyloid aggregates. By disrupting the aggregation process at this early stage, we may be able to prevent the progression of diseases related to TDP-43 aggregation. Hence, we decided to uncover the hidden, high-energy intermediates in equilibrium with the native states of TDP-43 by modulating the thermodynamic stability of the soluble native dimer (N form) and monomeric molten globular state (MG form) of full-length TDP-43. The thermodynamic modulation performed in the current study successfully revealed the highly aggregation-prone intermediate of full-length TDP-43, i.e., PUF. Moreover, we observed that along with high aggregation propensity, the aggregation kinetics and mechanisms of PUF differ from previously identified intermediates of full-length TDP-43 (the MG and I forms). The information regarding the initial aggregation-prone state of full-length TDP-43 could lead to therapies for amyloid diseases by halting early protein aggregation.

Investigating pH-induced conformational switch in PIM-1: An integrated multi spectroscopic and MD simulation study

PIM-1 is a Ser/Thr kinase, which has been extensively studied as a potential target for cancer therapy due to its significant roles in various cancers, including prostate and breast cancers. Given its importance in cancer, researchers are investigating the structure of PIM-1 for pharmacological inhibition to discover therapeutic intervention. This study examines structural and conformational changes in PIM-1 across different pH using various spectroscopic and computational techniques. Spectroscopic results indicate that PIM-1 maintains its secondary and tertiary structure within the pH range of 7.0-9.0. However, protein aggregation occurs in the acidic pH range of 5.0-6.0. Additionally, kinase assays suggested that PIM-1 activity is optimal within the pH range of 7.0-9.0. Subsequently, we performed a 100 ns all-atom molecular dynamics (MD) simulation to see the effect of pH on PIM-1 structural stability at the molecular level. MD simulation analysis revealed that PIM-1 retains its native conformation in alkaline conditions, with some residual fluctuations in acidic conditions as well. A strong correlation was observed between our MD simulation, spectroscopic, and enzymatic activity studies. Understanding the pH-dependent structural changes of PIM-1 can provide insights into its role in disease conditions and cellular homeostasis, particularly regarding protein function under varying pH conditions.

Unraveling the physiochemical characteristics and molecular insights of Zein protein through structural modeling and conformational dynamics: a synergistic approach between machine learning and molecular dynamics simulations

This research article presents a comprehensive investigation into the three-dimensional structure, physicochemical characteristics and conformational stability of the Zein protein. Machine learning (ML) based homology modeling approach, was employed to predict the 3D structure of Zein protein. Convolutional neural networks (CNNs) were utilized for refining the model, capturing complex spatial features and improving decoy refinement. The predicted 3D structure of Zein protein showed a high-confidence score, i.e. C-score of 0.96. Physiochemical characteristic was also analyzed to investigate its protonation and deprotonation behavior across a range of pH values. A comprehensive analysis of the titration curve and electrostatic charges was performed to uncover valuable molecular insights into the zein protein's charge distribution, electrostatic interactions and potential conformational changes. Molecular dynamics (MD) simulations were performed to analyze the zein structural behavior under different pH values (2.0, 4.5, 6.8, 10.0 and 12.5), ionic strengths (0 mM, 25 mM, 50 mM, 75 mM, 100 mM) and temperatures (300K, 350K, 375K). Our results demonstrated the influence of these factors on zein protein's stability and conformational dynamics. At extreme pH values of 2.0 and 12.5, the Zein protein exhibited increased structural deviations and potential unfolding, while intermediate pH values closer to the protein's isoelectric point (pI) demonstrated more compact and stable conformations. Analysis of root mean square deviation, radius of gyration, solvent accessible surface area and Ramachandran plot provided clear understandings of the protein's compactness and surface exposure, confirming the impact of pH, ionic strength and temperature on the protein's conformation.

In silico identification of α-bisabolol and letestuianin C as potential inhibitors of Trypanosoma brucei trypanothione reductase

Despite the recent advances in drug research, finding a safe, effective, and easy to use chemotherapy for human African trypanosomiasis (HAT) remains a challenging task. Trypanosomatids have developed resistance mechanisms towards melarsoprol (the current drug of choice), and the fact that it is poisonous is problematic. Therefore, a search for alternative therapeutics against the parasite is urgently needed. Natural products offer potential for drug discovery, but little or nothing is known about the target of inhibition or possible mode of inhibition. Therefore, this study aimed to use molecular docking and molecular dynamics simulations to evaluate 30 antitrypanosomal natural products as potential inhibitors of trypanothione reductase, a key protein necessary for the survival of the Trypanosoma brucei. The study also assessed the pharmacokinetic properties of the most promising compounds. Of the compounds evaluated, α-bisabolol, letestuianin C, waltherione, and mexicanin E were found to bind at the active site of TR and interact with Met115, Tyr112, and Trp23, which are essential for enzyme functioning. Molecular dynamic simulations revealed the sustained binding of α-bisabolol and letestuianin C throughout the simulation period, potentially obstructing the binding of the substrate (T[S]2) and impeding catalysis. The binding of these compounds to TR led to the presence of solvent molecules in the enzyme's active site, and this could potentially lead to protein aggregation. Furthermore, α-bisabolol and letestuianin C exhibited promising safety profiles. Consequently, α-bisabolol and letestuianin C have been shown to be viable candidates for targeting trypanothione reductase in the fight against human African trypanosomiasis.Communicated by Ramaswamy H. Sarma.

The missing link: ARID1B non-truncating variants causing Coffin-Siris syndrome due to protein aggregation

ARID1B is the most frequently mutated gene in Coffin-Siris syndrome (CSS). To date, the vast majority of causative variants reported in ARID1B are truncating, leading to nonsense-mediated mRNA decay. In the absence of experimental data, only few ARID1B amino acid substitutions have been classified as pathogenic, mainly based on clinical data and their de novo occurrence, while most others are currently interpreted as variants of unknown significance. The present study substantiates the pathogenesis of ARID1B non-truncating/NMD-escaping variants located in the SMARCA4-interacting EHD2 and DNA-binding ARID domains. Overexpression assays in cell lines revealed that the majority of EHD2 variants lead to protein misfolding and formation of cytoplasmic aggresomes surrounded by vimentin cage-like structures and co-localizing with the microtubule organisation center. ARID domain variants exhibited not only aggresomes, but also nuclear aggregates, demonstrating robust pathological effects. Protein levels were not compromised, as shown by quantitative western blot analysis. In silico structural analysis predicted the exposure of amylogenic segments in both domains due to the nearby variants, likely causing this aggregation. Genome-wide transcriptome and methylation analysis in affected individuals revealed expression and methylome patterns consistent with those of the pathogenic haploinsufficiency ARID1B alterations in CSS cases. These results further support pathogenicity and indicate two approaches for disambiguation of such variants in everyday practice. The few affected individuals harbouring EHD2 non-truncating variants described to date exhibit mild CSS clinical traits. In summary, this study paves the way for the re-evaluation of previously unclear ARID1B non-truncating variants and opens a new era in CSS genetic diagnosis.

Cell-type specific and differential expression of LINC-RSAS long noncoding RNA declines in the testes during ageing of the rat

Long noncoding RNAs (lncRNAs) have emerged as major regulators of gene expression, chromatin structure, epigenetic changes, post-transcriptional processing of RNAs, translation of mRNAs into proteins as well as contributing to the process of ageing. Ageing is a universal, slow, progressive change in almost all physiological processes of organisms after attaining reproductive maturity and often associated with age-related diseases. Mammalian testes contain various cell-types, vast reservoir of transcriptome complexity, produce haploid male gametes for reproduction and testosterone for development and maintenance of male sexual characters as well as contribute genetic variation to the species. We report age-related decline in expression and cellular localization of Long intergenic noncoding repeat-rich sense-antisense (LINC-RSAS) RNA in the testes and its major cell-types such as primary spermatocytes, Leydig cells and Sertoli cells during ageing of the rat. LINC-RSAS expression in testes increased from immature (4-weeks) to adult (16- and 44-weeks) and declined from adult (44-weeks) to nearly-old (70-weeks) rats. Genomic DNA methylation in the testes showed a similar pattern. Cell-type specific higher expression of LINC-RSAS was observed in primary spermatocytes (pachytene cells), Leydig cells and Sertoli cells of testes of adult rats. Over-expression of LINC-RSAS in cultured human cell lines revealed its possible role in cell-cycle control and apoptosis. We propose that LINC-RSAS expression is involved in molecular physiology of primary spermatocytes, Leydig cells and Sertoli cells of adult testes and its decline is associated with diminishing function of testes during ageing of the rat.

Exploring the Comprehensive Neuroprotective and Anticancer Potential of Afzelin

Neurodegenerative diseases (Alzheimer's disease, Parkinson's disease, Huntington's disease, and others) and cancer, seemingly disparate in their etiology and manifestation, exhibit intriguing associations in certain cellular and molecular processes. Both cancer and neurodegenerative diseases involve the deregulation of cellular processes such as apoptosis, proliferation, and DNA repair and pose a significant global health challenge. Afzelin (kaempferol 3-O-rhamnoside) is a flavonoid compound abundant in various plant sources. Afzelin exhibits a diverse range of biological activities, offering promising prospects for the treatment of diseases hallmarked by oxidative stress and deregulation of cell death pathways. Its protective potential against oxidative stress is also promising for alleviating the side effects of chemotherapy. This review explores the potential therapeutic implications of afzelin, including its capacity to mitigate oxidative stress, modulate inflammation, and promote cellular regeneration in neurodegenerative and cancer diseases.

In-depth investigation of the effect of pH on the autofluorescence properties of DPF3b and DPF3a amyloid fibrils

Double PHD fingers 3 (DPF3) protein exists as two splicing variants, DPF3b and DPF3a, the involvement of which in human cancer and neurodegeneration is beginning to be increasingly recognised. Both isoforms have recently been identified as intrinsically disordered proteins able to undergo amyloid fibrillation. Upon their aggregation, DPF3 proteins exhibit an intrinsic fluorescence in the visible range, referred to as deep-blue autofluorescence (dbAF). Comprehension of such phenomenon remaining elusive, we investigated in the present study the influence of pH on the optical properties of DPF3b and DPF3a fibrils. By varying the excitation wavelength and the pH condition, the two isoforms were revealed to display several autofluorescence modes that were defined as violet, deep-blue, and blue-green according to their emission range. Complementarily, analysis of excitation spectra and red edge shift plots allowed to better decipher their photoselection mechanism and to highlight isoform-specific excitation-emission features. Furthermore, the observed violation to Kasha-Vavilov's rule was attributed to red edge excitation shift effects, which were impacted by pH-mediated H-bond disruption, leading to changes in intramolecular charge and proton transfer, or π-electrons delocalisation. Finally, emergence of different autofluorescence emitters was likely related to structurally distinct fibrillar assemblies between isoforms, as well as to discrepancies in the amino acid composition of their aggregation prone regions.

Pathways of amyloid fibril formation and protein aggregation

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.

Bioinformatic analysis of human ZPR1 gene pathogenic exome mutations

Advanced sequencing technologies enable rapid detection of sequence variants, aiming to uncover the molecular foundations of human genetic disorders. The challenge lies in interpreting the influence of new exome variants that lead to diverse phenotypes. Our study introduces a detailed, multi-tiered method for assessing the impact of novel variants, particularly focusing on the zinc finger protein 1 (ZPR1) gene. Herein, we employed a combination of variant effect predictors, protein stability analyses, and the American College of Medical Genetics and Association of Molecular Pathology (ACMG/AMP) guidelines. Our structural analysis pinpoints specific amino acid residues in the ZPR1 zinc finger domains that are sensitive to changes, distinguishing between benign and disease-causing coding variants using rigorous in silico tools. We examined 223 germline ZPR1 exome variants, uncovering significant ethnic disparities in the frequency of heterozygous harmful ZPR1 variants, ranging from 0.04% in the Ashkenazi Jewish population to 0.34% in African/African Americans. Additionally, the discovery of three homozygous carriers in European and South Asian groups suggests a higher occurrence of ZPR1 variants in these demographics, meriting further exploration. This research provides insights into the prevalence and implications of amino acid substitutions in the ZPR1 protein.

KCNH6 channel promotes insulin exocytosis via interaction with Munc18-1 independent of electrophysiological processes

Glucose-stimulated insulin secretion (GSIS) in pancreatic islet β-cells primarily relies on electrophysiological processes. Previous research highlighted the regulatory role of KCNH6, a member of the Kv channel family, in governing GSIS through its influence on β-cell electrophysiology. In this study, we unveil a novel facet of KCNH6's function concerning insulin granule exocytosis, independent of its conventional electrical role. Young mice with β-cell-specific KCNH6 knockout (βKO) exhibited impaired glucose tolerance and reduced insulin secretion, a phenomenon not explained by electrophysiological processes alone. Consistently, islets from KCNH6-βKO mice exhibited reduced insulin secretion, conversely, the overexpression of KCNH6 in murine pancreatic islets significantly enhanced insulin release. Moreover, insulin granules lacking KCNH6 demonstrated compromised docking capabilities and a reduced fusion response upon glucose stimulation. Crucially, our investigation unveiled a significant interaction between KCNH6 and the SNARE protein regulator, Munc18-1, a key mediator of insulin granule exocytosis. These findings underscore the critical role of KCNH6 in the regulation of insulin secretion through its interaction with Munc18-1, providing a promising and novel avenue for enhancing our understanding of the Kv channel in diabetes mechanisms.

Could Targeting NPM1c+ Misfolding Be a Promising Strategy for Combating Acute Myeloid Leukemia?

Acute myeloid leukemia (AML) is a heterogeneous group of diseases classified into various types on the basis of distinct features concerning the morphology, cytochemistry and cytogenesis of leukemic cells. Among the different subtypes, the group "AML with gene mutations" includes the variations of the gene of the multifunctional protein nucleophosmin 1 (NPM1). These mutations are the most frequent (~30-35% of AML adult patients and less in pediatric ones) and occur predominantly in the C-terminal domain (CTD) of NPM1. The most important mutation is the insertion at W288, which determines the frame shift W288Cfs12/Ffs12/Lfs*12 and leads to the addition of 2-12 amino acids, which hamper the correct folding of NPM1. This mutation leads to the loss of the nuclear localization signal (NoLS) and to aberrant cytoplasmic localization, denoted as NPM1c+. Many investigations demonstrated that interfering with the cellular location and oligomerization status of NPM1 can influence its biological functions, including the proper buildup of the nucleolus, and therapeutic strategies have been proposed to target NPM1c+, particularly the use of drugs able to re-direct NPM1 localization. Our studies unveiled a direct link between AML mutations and the neat amyloidogenic character of the CTDs of NPM1c+. Herein, with the aim of exploiting these conformational features, novel therapeutic strategies are proposed that rely on the induction of the selective self-cytotoxicity of leukemic blasts by focusing on agents such as peptides, peptoids or small molecules able to enhance amyloid aggregation and targeting selectively AML-NPM1c+ mutations.

Effects of Cycloastragenol on Alzheimer's Disease in Rats by Reducing Oxidative Stress, Inflammation, and Apoptosis

BACKGROUND

As individuals age, they may develop Alzheimer's disease (AD), which is characterized by difficulties in speech, memory loss, and other issues related to neural function. Cycloastragenol is an active ingredient of Astragalus trojanus and has been used to treat inflammation, aging, heart disease, and cancer.

OBJECTIVES

This study aimed to explore the potential therapeutic benefits of cycloastragenol in rats with experimentally induced AD. Moreover, the underlying molecular mechanisms were also evaluated by measuring Nrf2 and HO-1, which are involved in oxidative stress, NFκB and TNF-α, which are involved in inflammation, and BCL2, BAX, and caspase-3, which are involved in apoptosis.

METHODS

Sprague-Dawley rats were given 70 mg/kg of aluminum chloride intraperitoneally daily for six weeks to induce AD. Following AD induction, the rats were given 25 mg/kg of cycloastragenol daily by oral gavage for three weeks. Hippocampal sections were stained with hematoxylin/ eosin and with anti-caspase-3 antibodies. The Nrf2, HO-1, NFκB, TNF-α, BCL2, BAX, and caspase-3 gene expressions and protein levels in the samples were analyzed.

RESULTS

Cycloastragenol significantly improved rats' behavioral test performance. It also strengthened the organization of the hippocampus. Cycloastragenol significantly improved behavioral performance and improved hippocampal structure in rats. It caused a marked decrease in the expression of NFκB, TNF-α, BAX, and caspase-3, which was associated with an increase in the expression of BCL2, Nrf2, and HO-1.

CONCLUSION

Cycloastragenol improved the structure of the hippocampus in rats with AD. It enhanced the outcomes of behavioral tests, decreased the concentration of AChE in the brain, and exerted antioxidant and anti-inflammatory effects. Antiapoptotic effects were also noted, leading to significant improvements in cognitive function, memory, and behavior in treated rats.

Non-coding RNAs in Regulation of Protein Aggregation and Clearance Pathways: Current Perspectives Towards Alzheimer's Research and Therapy

Alzheimer's disease (AD) is the leading cause of dementia, affecting approximately 45.0 million people worldwide and ranking as the fifth leading cause of mortality. AD is identified by neurofibrillary tangles (NFTs), which include abnormally phosphorylated tau-protein and amyloid protein (amyloid plaques). Peptide dysregulation is caused by an imbalance between the production and clearance of the amyloid-beta (Aβ) and NFT. AD begins to develop when these peptides are not cleared from the body. As a result, understanding the processes that control both normal and pathological protein recycling in neuronal cells is critical. Insufficient Aβ and NFT clearance are important factors in the development of AD. Autophagy, lysosomal dysfunction, and ubiquitin-proteasome dysfunction have potential roles in the pathogenesis of many neurodegenerative disorders, particularly in AD. Modulation of these pathways may provide a novel treatment strategy for AD. Non-coding RNAs (ncRNAs) have recently emerged as important biological regulators, with particular relevance to the emergence and development of neurodegenerative disorders such as AD. ncRNAs can be used as potential therapeutic targets and diagnostic biomarkers due to their critical regulatory functions in several biological processes involved in disease development, such as the aggregation and accumulation of Aβ and NFT. It is evident that ncRNAs play a role in the pathophysiology of AD. In this communication, we explored the link between ncRNAs and AD and their regulatory mechanisms that may help in finding new therapeutic targets and AD medications.

Anti-Aggregative and Protective Effects of Vicenin-2 on Heat and Oxidative Stress-Induced Damage on Protein Structures

Vicenin-2, a flavonoid categorized as a flavones subclass, exhibits a distinctive and uncommon C-glycosidic linkage. Emerging evidence challenges the notion that deglycosylation is not a prerequisite for the absorption of C-glycosyl flavonoid in the small intestine. Capitalizing on this experimental insight and considering its biological attributes, we conducted different assays to test the anti-aggregative and antioxidant capabilities of vicenin-2 on human serum albumin under stressful conditions. Within the concentration range of 0.1-25.0 μM, vicenin-2 effectively thwarted the heat-induced HSA fibrillation and aggregation of HSA. Furthermore, in this study, we have observed that vicenin-2 demonstrated protective effects against superoxide anion and hydroxyl radicals, but it did not provide defense against active chlorine. To elucidate the underlying mechanisms, behind this biological activity, various spectroscopy techniques were employed. UV-visible spectroscopy revealed an interaction between HSA and vicenin-2. This interaction involves the cinnamoyl system found in vicenin-2, with a peak of absorbance observed at around 338 nm. Further evidence of the interaction comes from circular dichroism spectrum, which shows that the formation of bimolecular complex causes a reduction in α-helix structures. Fluorescence and displacement investigations indicated modifications near Trp214, identifying Sudlow's site I, similarly to the primary binding site. Molecular modeling revealed that vicenin-2, in nonplanar conformation, generated hydrophobic interactions, Pi-pi stacking, and hydrogen bonds inside Sudlow's site I. These findings expand our understanding of how flavonoids bind to HSA, demonstrating the potential of the complex to counteract fibrillation and oxidative stress.

Sperm proteostasis: Can-nabinoids be chaperone's partners?

The male gamete is a highly differentiated cell that aims to fuse with the oocyte in fertilization. Sperm have silenced the transcription and translational processes, maintaining proteostasis to guarantee male reproductive health. Despite the information about the implication of molecular chaperones as orchestrators of protein folding or aggregation, and the handling of body homeostasis by the endocannabinoid system, there is still a lack of basic investigation and random controlled clinical trials that deliver more evidence on the involvement of cannabinoids in reproductive function. Besides, we noticed that the information regarding whether recreational marijuana affects male fertility is controversial and requires further investigation. In other cell models, it has recently been evidenced that chaperones and cannabinoids are intimately intertwined. Through a literature review, we aim to explore the interaction between chaperones and cannabinoid signaling in sperm development and function. To untangle how or whether this dialogue happens within the sperm proteostasis. We discuss the action of chaperones, the endocannabinoid system and phytocannabinoids in sperm proteostasis. Reports of some heat shock and lipid proteins interacting with cannabinoid receptors prove that chaperones and the endocannabinoid system are in an intimate dialogue. Meanwhile, advancing the evidence to decipher these mechanisms for introducing innovative interventions into routine clinical settings becomes crucial. We highlight the potential interaction between chaperones and cannabinoid signaling in regulating proteostasis in male reproductive health.

TRP channels: Role in neurodegenerative diseases and therapeutic targets

TRP (Transient receptor potential) channels are integral membrane proteins consisting of a superfamily of cation channels that allow permeability of both monovalent and divalent cations. TRP channels are subdivided into six subfamilies: TRPC, TRPV, TRPM, TRPP, TRPML, and TRPA, and are expressed in almost every cell and tissue. TRPs play an instrumental role in the regulation of various physiological processes. TRP channels are extensively represented in brain tissues and are present in both prokaryotes and eukaryotes, exhibiting responses to several mechanisms, including physical, chemical, and thermal stimuli. TRP channels are involved in the perturbation of Ca²⁺ homeostasis in intracellular calcium stores, both in neuronal and non-neuronal cells, and its discrepancy leads to several neuronal disorders such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and Amyotrophic lateral sclerosis (ALS). TRPs participate in neurite outgrowth, receptor signaling, and excitotoxic cell death in the central nervous system. Understanding the mechanism of TRP channels in neurodegenerative diseases may extend to developing novel therapies. Thus, this review articulates TRP channels' physiological and pathological role in exploring new therapeutic interventions in neurodegenerative diseases.