Nanopolyphenol rejuvenates microglial surveillance of multiple misfolded proteins through metabolic reprogramming

Microglial surveillance plays an essential role in clearing misfolded proteins such as amyloid-beta,tau,andα-synuclein aggregates in neurodegenerative diseases.However,due to the complex structure and ambiguous pathogenic species of the misfolded proteins,a universal approach to remove the misfolded proteins remains unavailable.Here,we found that a polyphenol,α-mangostin,reprogrammed metabolism in the disease-associated microglia through shifting glycolysis to oxidative phosphorylation,which holistically rejuvenated microglial surveillance capacity to enhance microglial phagocytosis and autophagy-mediated degradation of multiple misfolded proteins.Nanoformulation ofα-mangostin efficiently deliveredα-mangostin to microglia,relieved the reactive status and rejuvenated the misfolded-proteins clearance capacity of microglia,which thus impressively relieved the neuropathological changes in both Alzheimer’s disease and Parkinson’s disease model mice.These findings provide direct evidences for the concept of rejuvenating microglial surveillance of multiple misfolded proteins through metabolic reprogramming,and demonstrate nanoformulatedα-mangostin as a potential and universal therapy against neurodegenerative diseases.

OSMR is a potential driver of inflammation in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis is a neurodegenerative disease,and the molecular mechanism underlying its pathology remains poorly understood.However,inflammation is known to play an important role in the development of this condition.To identify driver genes that affect the inflammatory response in amyotrophic lateral sclerosis,as well as potential treatment targets,it is crucial to analyze brain tissue samples from patients with both sporadic amyotrophic lateral sclerosis and C9orf72-related amyotrophic lateral sclerosis.Therefore,in this study we used a network-driven gene analysis tool,NetBID2.0,which is based on SJARACNe,a scalable algorithm for the reconstruction of accurate cellular networks,to experimentally analyze sequencing data from patients with sporadic amyotrophic lateral sclerosis.The results showed that the OSMR gene is pathogenic in amyotrophic lateral sclerosis and participates in the progression of amyotrophic lateral sclerosis by mediating the neuroinflammatory response.Furthermore,there were differences in OSMR activity and expression between patients with sporadic amyotrophic lateral sclerosis and those with C9orf72-related amyotrophic lateral sclerosis.These findings suggest that OSMR may be a diagnostic and prognostic marker for amyotrophic lateral sclerosis.

Reduced mesencephalic astrocyte-derived neurotrophic factor expression by mutant androgen receptor contributes to neurodegeneration in a model of spinal and bulbar muscular atrophy pathology

Spinal and bulbar muscular atrophy is a neurodegenerative disease caused by extended CAG trinucleotide repeats in the androgen receptor gene,which encodes a ligand-dependent transcription facto r.The mutant androgen receptor protein,characterized by polyglutamine expansion,is prone to misfolding and forms aggregates in both the nucleus and cytoplasm in the brain in spinal and bulbar muscular atrophy patients.These aggregates alter protein-protein interactions and compromise transcriptional activity.In this study,we reported that in both cultured N2a cells and mouse brain,mutant androgen receptor with polyglutamine expansion causes reduced expression of mesencephalic astrocyte-de rived neurotrophic factor.Overexpressio n of mesencephalic astrocyte-derived neurotrophic factor amelio rated the neurotoxicity of mutant androgen receptor through the inhibition of mutant androgen receptor aggregation.Conversely.knocking down endogenous mesencephalic astrocyte-derived neurotrophic factor in the mouse brain exacerbated neuronal damage and mutant androgen receptor aggregation.Our findings suggest that inhibition of mesencephalic astrocyte-derived neurotrophic factor expression by mutant androgen receptor is a potential mechanism underlying neurodegeneration in spinal and bulbar muscular atrophy.

α-Synuclein oligomers and fibrils:partners in crime in synucleinopathies

The misfolding and aggregation of a-synuclein is the general hallmark of a group of devastating neurodegenerative pathologies referred to as synucleinopathies,such as Parkinson’s disease,dementia with Lewy bodies,and multiple system atrophy.In such conditions,a range of different misfolded aggregates,including oligomers,protofibrils,and fibrils,are present both in neurons and glial cells.Growing expe rimental evidence supports the proposition that solu ble oligomeric assemblies,formed during the early phases of the aggregation process,are the major culprits of neuronal toxicity;at the same time,fibrillar confo rmers appear to be the most efficient at propagating among interconnected neurons,thus contributing to the spreading ofα-synuclein pathology.Moreover,α-synuclein fibrils have been recently repo rted to release soluble and highly toxic oligomeric species,responsible for an immediate dysfunction in the recipient neurons.In this review,we discuss the current knowledge about the plethora of mechanisms of cellular dysfunction caused byα-synuclein oligome rs and fibrils,both contributing to neurodegeneration in synucleinopathies.

Alexander disease:the road ahead

Alexander disease is a rare neurodegenerative disorder caused by mutations in the glial fibrillary acidic protein,a type III intermediate filament protein expressed in astrocytes.Both early(infantile or juvenile)and adult onsets of the disease are known and,in both cases,astrocytes present characteristic aggregates,named Rosenthal fibers.Mutations are spread along the glial fibrillary acidic protein sequence disrupting the typical filament network in a dominant manner.Although the presence of aggregates suggests a proteostasis problem of the mutant forms,this behavior is also observed when the expression of wild-type glial fibrillary acidic protein is increased.Additionally,several isoforms of glial fibrillary acidic protein have been described to date,while the impact of the mutations on their expression and proportion has not been exhaustively studied.Moreover,the posttranslational modification patterns and/or the protein-protein interaction networks of the glial fibrillary acidic protein mutants may be altered,leading to functional changes that may modify the morphology,positioning,and/or the function of several organelles,in turn,impairing astrocyte normal function and subsequently affecting neurons.In particular,mitochondrial function,redox balance and susceptibility to oxidative stress may contribute to the derangement of glial fibrillary acidic protein mutant-expressing astrocytes.To study the disease and to develop putative therapeutic strategies,several experimental models have been developed,a collection that is in constant growth.The fact that most cases of Alexander disease can be related to glial fibrillary acidic protein mutations,together with the availability of new and more relevant experimental models,holds promise for the design and assay of novel therapeutic strategies.

Roles of constitutively secreted extracellular chaperones in neuronal cell repair and regeneration

Protein quality control involves many processes that jointly act to regulate the expression, localization, turnover, and degradation of proteins, and has been highlighted in recent studies as critical to the differentiation of stem cells during regeneration. The roles of constitutively secreted extracellular chaperones in neuronal injury and disease are poorly understood. Extracellular chaperones are multifunctional proteins expressed by many cell types, including those of the nervous system, known to facilitate protein quality control processes. These molecules exert pleiotropic effects and have been implicated as playing important protective roles in a variety of stress conditions, including tissue damage, infections, and local tissue inflammation. This article aims to provide a critical review of what is currently known about the functions of extracellular chaperones in neuronal repair and regeneration and highlight future directions for this important research area. We review what is known of four constitutively secreted extracellular chaperones directly implicated in processes of neuronal damage and repair, including transthyretin, clusterin, α2-macroglobulin, and neuroserpin, and propose that investigation into the effects of these and other extracellular chaperones on neuronal repair and regeneration has the potential to yield valuable new therapies.

Unraveling the molecular mechanism of prion disease:Insights fromα2 area mutations in human prion protein

Prion diseases are a class of fatal neurodegenerative diseases caused by misfolded prion proteins.The main reason is that pathogenic prion protein has a strong tendency to aggregate,which easily induces the damage to the central nervous system.Point mutations in the human prion protein gene can cause prion diseases such as Creutzfeldt-Jakob and Gerstmann's syndrome.To understand the mechanism of mutation-induced prion protein aggregation,the mutants in an aqueous solution are studied by molecular dynamics simulations,including the wild type,V180I,H187R and a double point mutation which is associated with CJD and GSS.After running simulations for 500 ns,the results show that these three mutations have different effects on the kinetic properties of PrP.The high fluctuations around the N-terminal residues of helix 2 in the V180I variant lead to a decrease in hydrogen bonding on helix 2,while an increase in the number of hydrogen bonds between the folded regions promotes the generation ofβ-sheet.Meanwhile,partial deletion of salt bridges in the H187R and double mutants allows the sub-structural domains of the prion protein to separate,which would accelerate the conversion from PrPC to PrPSc.A similar trend is observed in both SASA and Rg for all three mutations,indicating that the conformational space is reduced and the structure is compact.

The metabolome identity:basis for discovery of biomarkers in neurodegeneration

Neurodegenerative disorders are often associated with cellular dysfunction caused by underlying protein-misfolding signalling. Numerous neuropathologies are diagnosed at late stage symptomatic changes which occur in response to these molecular malfunctions and treatment is often too late or restricted only to the slowing of further cell death. Important new strategies to identify early biomarkers with predictive value to intervene with disease progression at stages where cell dysfunction has not progressed irreversibly is of paramount importance. Thus, the identification of these markers presents an essential opportunity to identify and target disease pathways. This review highlights some important metabolic alterations detected in neurodegeneration caused by misfolded prion protein and discusses common toxicity pathways identified across different neurodegenerative diseases. Thus, having established some commonalities between various degenerative conditions, detectable metabolic changes may be of extreme value as an early diagnostic biomarker in disease.

Using Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry to analyze differentially expressed brain polypeptides in scrapie strain 22L-infected BALB/c mice

Differentialiy expressed polypeptides in the brain of a BALB/c mouse model infected with scrapie strain 22L were analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The results showed that 21 peptides were down-regulated, with peptides of mass-to-charge ratio 758.772 5 and mass-to-charge ratio 5 432.206 9, demonstrating the most significant decreases. These finding suggest that these peptides are candidate biomarkers and may play an important role in the pathogenesis of prion disease.

Circulating extracellular vesicles:friends and foes in neurodegeneration

Extracellular vesicles have been identified as pivotal mediators of intercellular communication with critical roles in physiological and pathological conditions.Via this route,several molecules(e.g.,nucleic acids,proteins,metabolites) can be transferred to proximal and distant targets to convey specific information.Extracellular vesicle-associated cargo molecules have been proposed as markers of several disease conditions for their potential of tracking down the generating cell.Indeed,circulating extracellular vesicles may represent biomarkers of dysfunctional cellular quality control systems especially in conditions characterized by the accrual of intracellular misfolded proteins.Furthermore,the identification of extracellular vesicles as tools for the delivery of nucleic acids or other cargo molecules to diseased tissues makes these circulating shuttles possible targets for therapeutic development.The increasing interest in the study of extracellular vesicles as biomarkers resides mainly in the fact that the identification of peripheral levels of extracellular vesicle-associated proteins might reflect molecular events occurring in hardly accessible tissues,such as the brain,thereby serving as a "brain liquid biopsy".The exploitation of extracellular vesicles for diagnostic and therapeutic purposed might offer unprecedented opportunities to develop personalized approaches.Here,we discuss the bright and dark sides of extracellular vesicles in the setting of two main neurodegenerative diseases(i.e.,Parkinson's and Alzheimer's diseases).A special focus will be placed on the possibility of using extracellular vesicles as biomarkers for the two conditions to enable disease tracking and treatment monitoring.

The roles of the proteasome pathway in signal transduction and neurodegenerative diseases

There are two degradation systems in mammalian cells, autophagy/lysosomal pathway and ubiquitin-proteasome pathway. Proteasome is consist of multiple protein subunits and plays important roles in degradation of short-lived cellular proteins. Recent studies reveal that proteasomal degradation system is also involved in signal transduction and regulation of various cellular functions. Dysfunction or dysregulation of proteasomal function may thus be an important pathogenic mechanism in certain neurological disorders. This paper reviews the biological functions of proteasome in signal transduction and its potential roles in neurodegenerative diseases.

Amyloid cross-seeding between Ab and hIAPP in relation to the pathogenesis of Alzheimer and type 2 diabetes

Amyloid cross-seeding of different amyloid proteins is considered as a highly possible mechanism for exacerbating the transmissible pathogenesis of protein misfolding disease(PMDs)and for explaining a molecular link between different PMDs,including Alzheimer disease(AD)and type 2 diabetes(T2D),AD and Parkinson disease(PD),and AD and prion disease.Among them,AD and T2D are the most prevalent PMDs,affecting millions of people globally,while Ab and hIAPP are the causative peptides responsible for AD and T2D,respectively.Increasing clinical and epidemiological evidences lead to a hypothesis that the cross-seeding of Ab and hIAPP is more biologically responsible for a pathological link between AD and T2D.In this review,we particularly focus on(i)the most recent and important findings of amyloid cross-seeding between Ab and hIAPP from in vitro,in vivo,and in silico studies,(ii)a mechanistic role of structural compatibility and sequence similarity of amyloid proteins(beyond Ab and hIAPP)in amyloid cross-seeding,and(iii)several current challenges and future research directions in this lessstudied field.Review of amyloid cross-seeding hopefully provides some mechanistic understanding of amyloidogenesis and inspires more efforts for the better design of next-generation drugs/strategies to treat different PMDs simultaneously.

Polyglutamine toxicity in non-neuronal cells

The neurodegenerative polyglutamine diseases are caused various disease proteins. Although these mutant proteins are by an expansion of unstable polyglutamine repeats in expressed ubiquitously in neuronal and non-neuronal cells, they cause selective degeneration of specific neuronal populations. Recently, increasing evidence shows that polyglutamine disease proteins also affect non-neuronal cells. However, it remains unclear how the expression of polyglutamine proteins in non-neuronal cells contributes to the course of the polyglutamine diseases. Here, we discuss recent findings about the expression of mutant polyglutamine proteins in non-neuronal cells and their influence on neurological symptoms. Understanding the contribution of non-neuronal polyglutamine proteins to disease progres- sion will help elucidate disease mechanisms and also help in the development of new treatment options.

Heat Shock Protein 40 (Hsp40) and Hsp70 Protein Expression in Oral Squamous Cell Carcinoma (OSCC)

Introduction: As a chaperone, heat shock protein acts as central integrators of protein homeostasis in cell. The form of these functions is to help setting up a complex protein molecular fold (folded protein) in many important settings, such as growth, differentiation, and the ability to live. It has become clear that the control system plays an important role if the folding process fails or an error occurs, causing folding abnormalities and targeted functionality to accumulate. The accumulation of faulty protein folding would harm cells and can result in death. Apparently, there is a correlation between protein folding error with various diseases, such as diabetes mellitus and cancer. Method: We examined protein levels in all samples using Dotblott with monoclonal antibody anti-Hsp40 and anti-Hsp70. Levels of the protein content was read using a densitometer. Modification of Dot Blot was as follows: treatment was conducted with 3 × SSC, added with 20 mL blocking solution, add with total protein samples of 10 mg/ml on nitrocellulose paper, prehybridized, incubated at 70° for 30 seconds, incubated at 70° for 30 seconds with primary antibody anti-Hsp40 or Hsp70 protein and then added with second antibody HRP anti-Hsp40 or Hsp70 protein, treated with 3 × SSC and visualized with TSA HRP, and then administered with streptavidin, biothynil tyramide, and, finally, added with chromogen (DAB) in a confined space. Result: From the analysis of the data using Manova test with Wilk’s Lambda, there were significant differences in the levels of Hsp40 between Benign Oral Lesion (mean 688.31 area) and OSCC (mean 1354.59 area) patients (p 0.070), there was also a highly significant difference in Hsp70 levels between patients who experienced Benign Oral Lesion (mean 529.82 area) and OSCC (mean 1346.32 area) patients (p 0.006). Conclusion: OSCC patients have increased Hsp70 levels, so it is possible that something is going wrong in protein folding. Errors in protein folding result in a new homeostasis or inhibition of apoptosis and increasing cell proliferation that triggers carcinogenesis. Hsp40 acts as co-chaperones.

Viscoelasticity of amyloid plaques in transgenic mouse brain studied by Brillouin microspectroscopy and correlative Raman analysis

A myloidopathy is one of the most prominent hallmarks of Alkheimer's disease(AD),the leading cause of dementia worldwide,and is characterized by the accumulation of amyloid plaques in the brain parenchyma.The plaques consist of abnornal deposits mainly composed of an aggregation-prone protein fragment,B-amyloid 140/1-42,into the extracellular matrix.Brillouin micro-spectroscopy is an all-optical contactless technique that is based on the interaction between visible light and longitudinal acoustic waves or phonons,giving access to the viscoelasticity of a sample on a subcellular scale.Here,we describe the first application of micromechanical mapping based on Brillouin scattering spectroscopy to probe the stifness of individual amyloid plaques in the hippocampal part of the brain of a B-amyloid overexpressi ng transgenic mouse.Correlative analysis based on Brillouin and Raman microspectroscopy showed that amyloid plaques have a complex structure with a rigid core of B-pleated shoet conformation(B-aryloid)protein sur-rounded by a softer ring-shaped region richer in lipids and other protein conformations.These preliminary results give a new insight into the plaque biophysics and biomechanics,and a valuable contrast mechanism for the study and diagnosis of amnyloidopathy.

Human Prion Protein Conformational Changes Susceptibility: A Molecular Dynamics Simulation Study

Prion proteins are related to the development of incurable and invariably fatal neurodegenerative diseases in humans and animals. The pathogenicity involves the conversion of the host-encoded-alpha rich isoform of prion protein, PrPC, into a misfolded beta-strand rich conformer, PrPSc. Although it has already been described that many punctual mutations alter the stability of PrPC, making it more prone to adopt an abnormal misfolded structure, the majority of cases reported among general population are sporadic in wild-type organisms. Thus, in this work we studied the dynamics and stability profiles of wild-type human prion protein by Molecular Dynamics (MD) simulation at different solvent temperatures. This analysis brought out certain residues and segments of the prion protein as critical to conformational changes;these results are consistent with experimental reports showing that protein mutants in those positions are related to the development of disease.

Prion-induced neurotoxicity: Possible role for cell cycle activity and DNA damage response

Protein misfolding neurodegenerative diseases arisethrough neurotoxicity induced by aggregation of host proteins. These conditions include Alzheimer's disease, Huntington's disease, Parkinson's disease, motor neuron disease, tauopathies and prion diseases. Collectively, these conditions are a challenge to society because of the increasing aged population and through the real threat to human food security by animal prion diseases. It is therefore important to understand the cellular and molecular mechanisms that underlie protein misfolding--induced neurotoxicity as this will form the basis for designing strategies to alleviate their burden. Prion diseases are an important paradigm for neurodegenerative conditions in general since several of these maladies have now been shown to display prion--like phenomena. Increasingly, cell cycle activity and the DNA damage response are recognised as cellular events that participate in the neurotoxic process of various neurodegenerative diseases, and their associated animal models, which suggests they are truly involved in the pathogenic process and are not merely epiphenomena. Here we review the role of cell cycle activity and the DNA damage response in neurodegeneration associated with protein misfolding diseases, and suggest that these events contribute towards prion--induced neurotoxicity. In doing so, we highlight PrP transgenic Drosophila as a tractable model for the genetic analysis of transmissible mammalian prion disease.

A Review of Nutrients to Extend Healthspan and Avoid Cancer by Reducing the Amount of Protein Misfolding, Free Radicals, and Calcification

Two major causes of human aging include protein misfolding and free radicals. Protein misfolding occurs when proteins which are synthesized by cells do not have the proper amino acid sequence or do not achieve the correct three-dimensional configuration to function properly. Peer-reviewed scientific literature explains how these processes contribute to many age-associated diseases. A few examples include cancer, heart disease, dementias including Parkinson’s and Alzheimer’s diseases, and arthritis. This article reviews how protein misfolding can be slowed and even reversed by appropriate nutrition, potentially slowing and reversing these diseases. One cause of misfolding is mRNA translation occurring too rapidly for proper chaperone binding or protein folding. A second cause is deficiency of amino acids so improper tRNA binding occurs. A third cause is free radicals. They cause mutations promoting misfolding and cancer, and oxidize lipoproteins causing plaque in circulation promoting heart disease and stroke. Nutrients with proven actions will contribute to longer healthspans for our aging population. Healthspan is the number of healthy years before chronic or terminal diseases substantially impair the quality of life. This can be done especially by slowing and reversing these three causes of PM. Niacin, quercetin, EGCG, alpha-lipoic acid, N-acetyl-carnitine, tyrosine and cysteine address protein misfolding. Vitamin C and glutathione trap free radicals. Vitamin K amplifies free radical cancer killing by vitamin C and activates decalcification enzymes which remove calcium deposits in the circulatory system and strengthen bones. Apigenin activates the pathway of caloric restriction and induces cancer cell apoptosis. This article provides citations and explanations of the progress showing new ways to maintain health as we age. For convenience and cost savings, many of these ingredients can be consumed in supplement form, taken twice a day to maintain water-soluble nutrient levels.

Protein seeding in Alzheimer's disease and Parkinson's disease: Similarities and differences

Neurodegenerative pathology can be seeded by introduction of misfolded proteins and peptides into the nervous system. Models of Alzheimer's disease(AD) and Parkinson's disease(PD) have both demonstrated susceptibility to this seeding mechanism, emphasizing the role of misfolded conformations of disease-specific proteins and peptides in disease progression. Thinking of the amyloidogenic amyloid-beta peptide(Aβ) and alpha-synuclein(α-syn), of AD and PD, respectively, as prionoids requires a comparison of these molecules and the mechanisms underlying the progression of disease. Aβ and α-syn, despite their size differences, are both natively unstructured and misfold into β-structured conformers. Additionally, several studies implicate the significant role of membrane interactions, such as those with lipid rafts in the plasma membrane, in mediating protein aggregation and transfer of Aβ and α-syn between cells that may be common to both AD and PD. Examination of inter-neuronal transfer of proteins/peptides provides evidence into the core mechanism of neuropathological propagation. Specifically, uptake of aggregates likely occurs by the endocytic pathway, possibly in response to their formation of membrane pores via a mechanism shared with pore-forming toxins. Failure of cellular clearance machinery to degrade misfolded proteins favours their release into the extracellular space, where they can be taken up by directly connected, nearby neurons. Although similarities between AD and PD are frequent and include mechanistically similar transfer processes, what differentiates these diseases, in terms of temporal and spatial patterns of propagation, may be in part due to the differing kinetics of protein misfolding. Several examples of animal models demonstrating seeding and propagation by exogenous treatment with Aβ and α-syn highlight the importance of both the environment in which these seeds are formed as well as the environment into which the seeds are propagated. Although these studies suggest potent seeding effects by both Aβ and α-syn, they emphasize the need for future studies to thoroughly characterize "seeds" as well as analyze changes in the nervous system in response to exogenous insults.

Effects of Klebsiella pneumoniae on Toll-Like Receptor-Dependent Endoplasmic Reticulum Stress-Related Signaling Pathways and Gene Expression and Promotes HLA-B27 Misfolding

Klebsiella has been considered as initiator of AS （ankylosing spondylitis） for nearly four decades. This study aimed to demonstrate that Klebsiella triggers ERS （endoplasmic reticulum stress） and HLA-B27 heavy chain misfolding. CA46 cells or splenocytes obtained from wild-type, MyD88/ or TLR9/ mice were stimulated with KP （Klebsiella pneumoniae） or its components including CPS （capsule polysaccharide）, LPS （lipopolysaccharide）, and KP gDNA （genomic deoxyribonucleic acid） respectively for 24 h and 48 h. The activation of ERS-related signaling was detected by Western blotting or RT-PCR, and the level of misfolded HLA-B27 was determined by non-reducing protein gel electrophoresis and Western blotting. The protein expression of BiP/Grp78 and calreticulin, the alternative splicing of XBP-1 mRNA （messenger ribonucleic acid）, and the activation of caspase-12 and p38 were increased in a dose-dependent manner in HLA-B27-expressing CA46 cells after treatment with decapsulated KP. We also demonstrate that the EP, S-inducing effects occur via the TLR （Toll-like receptor）/MyD88-dependent signaling pathway. Significantly, HLA-B27 misfolding was also detected in decapsulated KP-treated B27-expressing cells. These results suggest that the non-antigen-specific induction of ERS and B27 misfoiding through TLR/MyD88 signaling might promote KP antigen-initiated autoreactive responses via the presentation of misfolded B27, and that small-molecules targeting TLRs might have potential as novel therapeutic agents for AS.