Advances in protein misfolding, amyloidosis and its correlation with human diseases

More than Just Protein Folding: The Epichaperome, Mastermind of the Cancer Cell

The epichaperome, a dynamic and integrated network of chaperone proteins, extends its roles beyond basic protein folding to protein stabilization and intracellular signal transduction to orchestrating a multitude of cellular processes critical for tumor survival. In this review, we explore the multifaceted roles of the epichaperome, delving into its diverse cellular locations, factors that modulate its formation and function, its liquid-liquid phase separation, and the key signaling and crosstalk pathways it regulates, including cellular metabolism and intracellular signal transduction. We further highlight techniques for isolating and identifying epichaperome networks, pitfalls, and opportunities. Further, we review the profound implications of the epichaperome for cancer treatment and therapy design, underscoring the need for strategic engineering that hinges on a comprehensive insight into the comprehensive structure and workings of the epichaperome across the heterogeneous cell subpopulations in the tumor milieu. By presenting a holistic view of the epichaperome's functions and mechanisms, we aim to underscore its potential as a key target for novel anti-cancer strategies, revealing that the epichaperome is not merely a piece of protein folding machinery but a mastermind that facilitates the malignant phenotype.

Characterization and kinetics of whey protein isolate amyloid fibril aggregates under moderate electric fields

Food proteins solutions enable the controlled flow of electrical current when subjected to a Moderate electric field (MEF). This application results in internal heat generation, known as ohmic heating, accompanied by electrochemical reactions. These effects play a significant role in influencing the formation of protein amyloid fibril aggregates (AFA), which have broad applications in food and biomedical fields, ranging from improving food texture to biomedical applications such as drug delivery and disease treatment. This study focused on investigating the formation of β-Lactoglobulin (β-lg) AFA under MEF conditions using WPI as protein source and various characterization techniques (e.g., Thioflavin T fluorescence, circular dichroism, and electron microscopy). The results indicated that MEF prolonged the lag phase of AFA formation. Furthermore, nucleation and fibril growth showed higher activation coefficients and cooperativity level (n > 2) compared to conventional heating method. MEF treatment resulted in unique fibril clustering and the presence of unexpected higher-order AFA networks confirmed by electron microscopy. These findings highlight the significant role of MEF in influencing the aggregation kinetics of β-lg AFA. Exploring further into the electrochemical and thermal effects during protein aggregation processes holds the key to unlocking deeper insights into fibril formation process.

Diosgenin loaded cellulose nanoonion impedes different stages of protein aggregation induced cell death via alleviating mitochondrial dysfunction and upregulation of autophagy

Protein aggregation is a multifaceted phenomenon prevalent in the progression of neurodegenerative diseases, yielding aggregates of diverse sizes. Recently, increased attention has been directed towards early protein aggregates due to their pronounced toxicity, largely stemming from inflammation mediated by reactive oxygen species (ROS). This study advocates for a therapeutic approach focusing on inflammation control rather than mere ROS inhibition in the context of neurodegenerative disorders. Here, we introduced Camellia sinensis cellulose nanoonion (CS-CNO) as an innovative, biocompatible nanocarrier for encapsulating the phytosteroid diosgenin (DGN@CS-CNO). The resulting nano-assembly, manifesting as spherical entities with dimensions averaging ~180-220 nm, exhibits a remarkable capacity for the gradual and sustained release of approximately 39-44 % of DGN over a 60-hour time frame. DGN@CS-CNO displays a striking ability to inhibit or disassemble various phases of hen egg white lysozyme (HEWL) protein aggregates, including the early (HEWLEA) and late (HEWLLA) stages. In vitro experiments employing HEK293 cells underscore the potential of DGN@CS-CNO in mitigating cell death provoked by protein aggregation. This effect is achieved by ameliorating ROS-mediated inflammation and countering mitochondrial dysfunction, as evidenced by alterations in TNFα, TLR4, and MT-CO1 protein expression. Western blot analyses reveal that the gradual and sustained release of DGN from DGN@CS-CNO induces autophagy, a pivotal process in dismantling intracellular amyloid deposits. In summary, this study not only illuminates a path forward but also presents a compelling case for the utilization of phytosteroid as a formidable strategy against neuroinflammation incited by protein aggregation.

Novel Dual-Acting Hybrids Targeting Type-2 Cannabinoid Receptors and Cholinesterase Activity Show Neuroprotective Effects In Vitro and Amelioration of Cognitive Impairment In Vivo

Alzheimer's disease (AD) is a neurodegenerative form of dementia characterized by the loss of synapses and a progressive decline in cognitive abilities. Among current treatments for AD, acetylcholinesterase (AChE) inhibitors have efficacy limited to symptom relief, with significant side effects and poor compliance. Pharmacological agents that modulate the activity of type-2 cannabinoid receptors (CB2R) of the endocannabinoid system by activating or blocking them have also been shown to be effective against neuroinflammation. Herein, we describe the design, synthesis, and pharmacological effects in vitro and in vivo of dual-acting compounds that inhibit AChE and butyrylcholinesterase (BChE) and target CB2R. Within the investigated series, compound 4g proved to be the most promising. It achieved IC50 values in the low micromolar to submicromolar range against both human cholinesterase isoforms while antagonizing CB2R with Ki of 31 nM. Interestingly, 4g showed neuroprotective effects on the SH-SY5Y cell line thanks to its ability to prevent oxidative stress-induced cell toxicity and reverse scopolamine-induced amnesia in the Y-maze forced alternation test in vivo.

Bovine liver catalase turns into three conformational states after exposure to an anionic surfactant

The mechanism by which anionic surfactants promote amyloid fibril is not well understood. Here, we investigated how sodium dodecyl sulfate (SDS), a negatively charged surfactant, affects the fibrillation of the partially unfolded random-coiled bovine liver catalase (BLC) at a pH of 2.0. We used several methods, including turbidity, RLS kinetics, intrinsic fluorescence, ThT fluorescence, far-UV CD, and TEM imaging, to evaluate the conformational changes of BLC in vitro in response to SDS treatment. BLC is a multimeric protein and well folded at physiological pH but forms a random coil structure at pH 2.0. Intrinsic fluorescence and far-UV CD data showed that below 0.1 mM SDS, random coiled BLC turned into a native-like structure. BLC incubated with an SDS concentration ranging from 0.1 to 2.0 mM led to the formation of aggregates. The ThT fluorescence intensity was enhanced in the aggregated BLC samples (0.1-2.0 mM SDS), and cross beta-sheeted structure was detected by the far UV CD measurements. BLC adopts a complete alpha-helical structure upon interacting with SDS at a more than 2.0 mM concentration at pH 2.0. Understanding the mechanism of surfactant- or lipid-induced fibrillation is important for therapeutic purposes.

Myelin in Alzheimer's disease: culprit or bystander?

Alzheimer's disease (AD) is a neurodegenerative disorder with neuronal and synaptic losses due to the accumulation of toxic amyloid β (Αβ) peptide oligomers, plaques, and tangles containing tau (tubulin-associated unit) protein. While familial AD is caused by specific mutations, the sporadic disease is more common and appears to result from a complex chronic brain neuroinflammation with mitochondriopathies, inducing free radicals' accumulation. In aged brain, mutations in DNA and several unfolded proteins participate in a chronic amyloidosis response with a toxic effect on myelin sheath and axons, leading to cognitive deficits and dementia. Αβ peptides are the most frequent form of toxic amyloid oligomers. Accumulations of misfolded proteins during several years alters different metabolic mechanisms, induce chronic inflammatory and immune responses with toxic consequences on neuronal cells. Myelin composition and architecture may appear to be an early target for the toxic activity of Aβ peptides and others hydrophobic misfolded proteins. In this work, we describe the possible role of early myelin alterations in the genesis of neuronal alterations and the onset of symptomatology. We propose that some pathophysiological and clinical forms of the disease may arise from structural and metabolic disorders in the processes of myelination/demyelination of brain regions where the accumulation of non-functional toxic proteins is important. In these forms, the primacy of the deleterious role of amyloid peptides would be a matter of questioning and the initiating role of neuropathology would be primarily the fact of dysmyelination.

Evolutionarily conserved regulators of tau identify targets for new therapies

Tauopathies are neurodegenerative diseases that involve the pathological accumulation of tau proteins; in this family are Alzheimer disease, corticobasal degeneration, and chronic traumatic encephalopathy, among others. Hypothesizing that reducing this accumulation could mitigate pathogenesis, we performed a cross-species genetic screen targeting 6,600 potentially druggable genes in human cells and Drosophila. We found and validated 83 hits in cells and further validated 11 hits in the mouse brain. Three of these hits (USP7, RNF130, and RNF149) converge on the C terminus of Hsc70-interacting protein (CHIP) to regulate tau levels, highlighting the role of CHIP in maintaining tau proteostasis in the brain. Knockdown of each of these three genes in adult tauopathy mice reduced tau levels and rescued the disease phenotypes. This study thus identifies several points of intervention to reduce tau levels and demonstrates that reduction of tau levels via regulation of this pathway is a viable therapeutic strategy for Alzheimer disease and other tauopathies.

Selective vitamins as potential options for dietary therapeutic interventions: In silico and In vitro insights from mutant C terminal fragment of FGA

We have used an integrated computational approach to explore the role of vitamin C and vitamin D in preventing aggregation of Fibrinogen A alpha-chain (FGA^cter) protein responsible for renal amyloidosis. We modelled structures of E524K / E526K mutants of FGA^cter protein and examined the potential interactions of these mutants with vitamin C and vitamin D3. Interaction of these vitamins at the amyloidogenic site may prevent the intermolecular interaction required for amyloid formation. The binding free energy values of vitamin C and vitamin D3 for E524K FGA^cter and E526K FGA^cter are - 67.12 ± 30.46 kJ/mole and - 79.45 ± 26.12 kJ/mol, respectively. Experimental studies using Congo red absorption, aggregation index studies and AFM imaging show encouraging results. The AFM images of E526K FGA^cter contained more extensive and higher protofibril aggregates, whereas, in the presence of vitamin D3, small monomeric and oligomeric aggregates were observed. Overall, the works provide interesting results about vitamin C and D role in preventing renal amyloidosis.

Flavonol glycoside complanatoside A requires FOXO/DAF-16, NRF2/SKN-1, and HSF-1 to improve stress resistances and extend the life span of Caenorhabditis elegans

Aging is associated with the increased risk of most age-related diseases in humans. Complanatoside A (CA) is a flavonoid compound isolated from the herbal medicine Semen Astragali Complanati. CA was reported to have potential anti-inflammatory and anti-oxidative activities. In this study, we investigated whether CA could increase the stress resistance capability and life span of Caenorhabditis elegans. Our results showed that CA could extend the longevity of C. elegans in a dosage-dependent manner, while 50 μM of CA has the best effect and increased the life span of C. elegans by about 16.87%. CA also improved the physiological functions in aging worms, such as enhanced locomotor capacity, and reduced the accumulation of the aging pigment. CA could also reduce the accumulation of toxic proteins (α-synuclein and β-amyloid) and delay the onset of neurodegenerative disorders, such as Alzheimer’s disease and Parkinson’s disease, in models of C. elegans. Further investigation has revealed that CA requires DAF-16/FOXO, SKN-1, and HSF-1 to extend the life span of C. elegans. CA could increase the antioxidation and detoxification activities regulated by transcription factor SKN-1 and the heat resistance by activating HSF-1 that mediated the expression of the chaperone heat shock proteins. Our results suggest that CA is a potential antiaging agent worth further research for its pharmacological mechanism and development for pharmaceutical applications.

Potential alternatives to current cholinesterase inhibitors: an in silico drug repurposing approach

Acetylcholinesterase/Butyrylcholinesterase inhibitors are considered an effective method for treating Alzheimer's disease (AD). In this current work, we have computationally analyzed 11 new small molecule drugs used in various neurological diseases and Donepezil, a known inhibitor of acetylcholinesterase, as a positive control. We investigated these drugs for possible fundamental interactions with acetylcholinesterase and butyrylcholinesterase as both are critical in the pathophysiology of Alzheimer's disease. We have selected FDA approved compounds for repurposing as possible inhibitors of these enzymes and novel therapeutic option for Alzheimer's disease. We selected the top two molecules for each protein for their binding energies, interactions, and Donepezil, the most commonly used drug for AD treatment. Molecular simulation and dynamics studies of the top 2 drugs in each case and free energy analysis helped us reach further conclusions about the best possible drugs for repurposing. Brexipirazole and Deutetrabenazine produce encouraging results as butyrylcholinesterase and acetylcholinesterase inhibitors, respectively.

Purines and Pyrimidines: Metabolism, Function and Potential as Therapeutic Options in Neurodegenerative Diseases

Various neurodegenerative disorders have various molecular origins but some common molecular mechanisms. In the current scenario, there are very few treatment regimens present for advanced neurodegenerative diseases. In this context, there is an urgent need for alternate options in the form of natural compounds with an ameliorating effect on patients. There have been individual scattered experiments trying to identify potential values of various intracellular metabolites. Purines and Pyrimidines, which are vital molecules governing various aspects of cellular biochemical reactions, have been long sought as crucial candidates for the same, but there are still many questions that go unanswered. Some critical functions of these molecules associated with neuromodulation activities have been identified. They are also known to play a role in foetal neurodevelopment, but there is a lacuna in understanding their mechanisms. In this review, we have tried to assemble and identify the importance of purines and pyrimidines, connecting them with the prevalence of neurodegenerative diseases. The leading cause of this class of diseases is protein misfolding and the formation of amyloids. A direct correlation between loss of balance in cellular homeostasis and amyloidosis is yet an unexplored area. This review aims at bringing the current literature available under one umbrella serving as a foundation for further extensive research in this field of drug development in neurodegenerative diseases.