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.

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.

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.

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.

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.

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.

Current understanding of the molecular mechanisms in Parkinson's disease:Targets for potential treatments

Gradual degeneration and loss of dopaminergic neurons in the substantia nigra,pars compacta and subsequent reduction of dopamine levels in striatum are associated with motor deficits that characterize Parkinson’s disease(PD).In addition,half of the PD patients also exhibit frontostriatal-mediated executive dysfunction,including deficits in attention,short-term working memory,speed of mental processing,and impulsivity.The most commonly used treatments for PD are only partially or transiently effective and are available or applicable to a minority of patients.Because,these therapies neither restore the lost or degenerated dopaminergic neurons,nor prevent or delay the disease progression,the need for more effective therapeutics is critical.In this review,we provide a comprehensive overview of the current understanding of the molecular signaling pathways involved in PD,particularly within the context of how genetic and environmental factors contribute to the initiation and progression of this disease.The involvement of molecular chaperones,autophagy-lysosomal pathways,and proteasome systems in PD are also highlighted.In addition,emerging therapies,including pharmacological manipulations,surgical procedures,stem cell transplantation,gene therapy,as well as complementary,supportive and rehabilitation therapies to prevent or delay the progression of this complex disease are reviewed.

Effect of the micro-environment on α-synuclein conversion and implication in seeded conversion assays

Background: α-Synuclein is a small soluble protein,whose physiological function in the healthy brain is poorly understood.Intracellular inclusions of α-synuclein,referred to as Lewy bodies(LBs),are pathological hallmarks ofαsynucleinopathies,such as Parkinson’s disease(PD)or dementia with Lewy bodies(DLB).Main body:Understanding of the molecular basis as well as the factors or conditions promoting α-synuclein misfolding and aggregation is an important step towards the comprehension of pathological mechanism ofαsynucleinopathies and for the development of efficient therapeutic strategies.Based on the conversion and aggregation mechanism of α-synuclein,novel diagnostic tests,such as protein misfolding seeded conversion assays,e.g.the real-time quaking-induced conversion(RT-QuIC),had been developed.In diagnostics, α-synuclein RT-QuIC exhibits a specificity between 82 and 100%while the sensitivity varies between 70 and 100%among different laboratories.In addition,the α-synuclein RT-QuIC can be used to study the α-synuclein-seeding-characteristics of different α-synucleinopathies and to differentiate between DLB and PD.Conclusion:The variable diagnostic accuracy of current α-synuclein RT-QuIC occurs due to different protocols,cohorts and material etc..An impact of micro-environmental factors on the α-synuclein aggregation and conversion process and the occurrence and detection of differential misfolded α-synuclein types or strains might underpin the clinical heterogeneity of α-synucleinopathies.

Does wild-type Cu/Zn-superoxide dismutase have pathogenic roles in amyotrophic lateral sclerosis?

Amyotrophic lateral sclerosis(ALS)is characterized by adult-onset progressive degeneration of upper and lower motor neurons.Increasing numbers of genes are found to be associated with ALS;among those,the first identified gene,SOD1 coding a Cu/Zn-superoxide dismutase protein(SOD1),has been regarded as the gold standard in the research on a pathomechanism of ALS.Abnormal accumulation of misfolded SOD1 in affected spinal motor neurons has been established as a pathological hallmark of ALS caused by mutations in SOD1(SOD1-ALS).Nonetheless,the involvement of wild-type SOD1 remains quite controversial in the pathology of ALS with no SOD1 mutations(non-SOD1 ALS),which occupies more than 90%of total ALS cases.In vitro studies have revealed post-translationally controlled misfolding and aggregation of wild-type as well as of mutant SOD1 proteins;therefore,SOD1 proteins could be a therapeutic target not only in SOD1-ALS but also in more prevailing cases,non-SOD1 ALS.In order to search for evidence on misfolding and aggregation of wild-type SOD1 in vivo,we reviewed pathological studies using mouse models and patients and then summarized arguments for and against possible involvement of wild-type SOD1 in non-SOD1 ALS as well as in SOD1-ALS.

Outline and computational approaches of protein misfolding

Protein misfolding is a general causation of classical conformational diseases and many pathogenic changes that are the result of structural conversion.Here I review recent progress in clinical and computational approaches for each stage of the misfolding process,aiming to present readers an outline for swift comprehension of this field.

Adenosine A1 receptor ligands bind toα-synuclein:implications forα-synuclein misfolding andα-synucleinopathy in Parkinson’s disease

Background:Accumulatingα-synuclein(α-syn)aggregates in neurons and glial cells are the staples of many synucleinopathy disorders,such as Parkinson’s disease(PD).Since brain adenosine becomes greatly elevated in ageing brains and chronic adenosine A1 receptor(A1R)stimulation leads to neurodegeneration,we determined whether adenosine or A1R receptor ligands mimic the action of known compounds that promoteα-syn aggregation(e.g.,the amphetamine analogue 2-aminoindan)or inhibitα-syn aggregation(e.g.,Rasagiline metabolite 1-aminoindan).In the present study,we determined whether adenosine,A1R receptor agonist N^(6)-Cyclopentyladenosine(CPA)and antago-nist 8-cyclopentyl-1,3-dipropylxanthine(DPCPX)could directly interact withα-syn to modulateα-syn aggregation and neurodegeneration of dopaminergic neurons in the substantia nigra(SN).Methods:Nanopore analysis and molecular docking were used to test the binding properties of CPA and DPCPX withα-syn in vitro.Sprague-Dawley rats were administered with 7-day intraperitoneal injections of the A1R ligands and 1-and 2-aminoindan,and levels ofα-syn aggregation and neurodegeneration were examined in the SN pars compacta and hippocampal regions using confocal imaging and Western blotting.Results:Using nanopore analysis,we showed that the A1R agonists(CPA and adenosine)interacted with the N-terminus ofα-syn,similar to 2-aminoindan,which is expected to promote a“knot”conformation andα-syn misfolding.In contrast,the A1R antagonist DPCPX interacted with the N-and C-termini ofα-syn,similar to 1-aminoindan,which is expected to promote a“loop”conformation that preventsα-syn misfolding.Molecular docking studies revealed that adenosine,CPA and 2-aminoindan interacted with the hydrophobic core ofα-syn N-terminus,whereas DPCPX and 1-aminoindan showed direct binding to the N-and C-terminal hydrophobic pockets.Confocal imaging and Western blot analyses revealed that chronic treatments with CPA alone or in combination with 2-aminoindan increasedα-syn expression/aggregation and neurodegeneration in both SN pars compacta and hippocampus.In contrast,DPCPX and 1-aminoindan attenuated the CPA-inducedα-syn expression/aggregation and neurodegeneration in SN and hippocampus.Conclusions:The results indicate that A1R agonists and drugs promoting a“knot”conformation ofα-syn can causeα-synucleinopathy and increase neuronal degeneration,whereas A1R antagonists and drugs promoting a“loop”con-formation ofα-syn can be harnessed for possible neuroprotective therapies to decreaseα-synucleinopathy in PD.