Α-synuclein Research Articles

Bivalent dopamine agonists with co-operative binding and functional activities at dopamine D2 receptors, modulate aggregation and toxicity of alpha synuclein protein

To follow up on our previous report on bivalent compounds exhibiting potent co-operative binding at dopamine D2 receptors, we modified the structure of the linker in our earlier bivalent molecules (S)-6-((9-(((R)-5-hydroxy-1,2,3,4-tetrahydronaphthalen-2-yl)(propyl)amino)nonyl)-(propyl)amino)-5,6,7,8-tetrahydronaphthalen-1-ol (Ia) and (S)-6-((10-(((R)-5-hydroxy-1,2,3,4-tetrahydronaphthalen-2-yl)(propyl)amino)decyl)(propyl)amino)-5,6,7,8-tetrahydronaphthalen-1-ol (Ib) (Fig. 1) connecting the two pharmaophoric moieties to observe any tolerance in maintaining similar affinities and potencies. Specifically, we introduced aromatic and piperazine moieties in the linker to explore their effect. Overall, similar activities at D2 receptors as observed in our earlier study was maintained in the new molecules e.g. (6S,6′S)-6,6′-((1,4-phenylenebis(ethane-2,1-diyl))bis(propylazanediyl))bis(5,6,7,8-tetrahydronaphthalen-1-ol) (D-382) (Ki, D2 = 3.88 nM). The aromatic moiety in D-382 was next functionalized by introducing hydroxyl groups to mimic polyhydroxy natural products which are known to interact with amyloidogenic proteins. Such a transformation resulted in development of compounds like 2,5-bis(2-(((S)-5-hydroxy-1,2,3,4-tetrahydronaphthalen-2-yl)(propyl)amino)ethyl)benzene-1,4-diol (D-666) (Ki, D2 = 7.62 nM) which retained similar affinity and potency at D2 receptors. Such dihydroxyl compounds turned out to be potent inhibitors against aggregation and toxicity of recombinant alpha synuclein protein. The work reported here is in line with our overall goal to develop multifunctional dopamine agonist for symptomatic and disease modifying treatment of Parkinson’s disease.

Heterozygote Dopamine Transporter Knockout Rats Display Enhanced Cocaine Locomotion in Adolescent Females

Cocaine is a powerful psychostimulant that is one of the most widely used illicit addictive. The dopamine transporter (DAT) plays a major role in mediating cocaine's reward effect. Decreases in DAT expression increase rates of drug abuse and vulnerability to comorbid psychiatric disorders. We used the novel DAT transgenic rat model to study the effects of cocaine on locomotor behaviors in adolescent rats, with an emphasis on sex. Female rats showed higher response rates to cocaine at lower acute and chronic doses, highlighting a higher vulnerability and perceived gender effects. In contrast, locomotor responses to an acute high dose of cocaine were more marked and sustained in male DAT heterozygous (HET) adolescents. The results demonstrate the augmented effects of chronic cocaine in HET DAT adolescent female rats. Knockout (KO) DAT led to a level of hyperdopaminergia which caused a marked basal hyperactivity that was unchanged, consistent with a possible ceiling effect. We suggest a role of alpha synuclein (α-syn) and PICK 1 protein expressions to the increased vulnerability in female rats. These proteins showed a lower expression in female HET and KO rats. This study highlights gender differences associated with mutations which affect DAT expression and can increase susceptibility to cocaine abuse in adolescence.

Mass spectrometry synuclein detection in human plasma

AbstractBackgroundSynucleins (alpha, beta, and gamma) are potential biomarkers for Parkinson’s disease dementia (PDD), Dementia of Lewy body (DLB) and the Multi system atrophy (MSA). Their quantification with Mass spectrometry (MS) represents an interesting approach as it can precisely quantify synuclein proteoforms including mutations, alternative splicing, phosphorylation and other post‐translational modifications.MethodsWe developed an antibody free method starting with 95 µl of plasma. Patient cohort of 155 samples was analyzed with 57% PD, 22% LBD, 6% MSA, and 15% of control (CTRL) patient samples. Briefly, plasma proteins were differentially precipitated, clean‐up on AssayMap BRAVO (Agilent Technologies) and digest with trypsin/lys C. Liquid Chromatography‐Multiple Reaction Monitoring (LC‐MRM, Nexera Mikros – 8060, Shimadzu) method was developed to monitor 14 peptides originated from the alpha, beta and gamma synuclein sequence and one hemoglobin peptide. Method was validated following the EMA guidelines and compare to alpha synuclein immunodetection with Meso Scale Discovery platform (U‐plex human alpha synuclein kit).ResultsQuantitative assay based on LC‐MRM was validated on total alpha (140aa), beta (134aa) and gamma (127aa) synuclein peptides, and 4 alpha synuclein proteoforms (126, 112, 98 and 41) using 3 proteotypic peptides (one for 126/98, one for 112/98 and one for 41). After cohort quantification, alpha and beta synucleins were quantified in plasma with good performances and are able to statistically discriminate CTRL vs PD; CTRL vs LBD; CTRL vs MSA, and MSA vs PD. A slight correlation was found between the quantities obtain between MSD and MS assays.ConclusionMS based assay was successfully developed and validated to plasma synuclein proteoforms. Analysis of patient cohort indicate the ability of this assay to discriminate PD, DLB and MSA with a specificity of 81% and a sensitivity of 87%.

Investigating Distinct Alpha Synuclein Oligomer‐Mediated Cellular Toxicity

AbstractBackgroundAlpha Synuclein (ASyn), an amyloidogenic protein observed in Parkinson’s (PD) and Alzheimer’s (AD) disease, oligomers are toxic and polymorphic protein aggregates that with further investigation could be essential to improving potential neurodegenerative therapeutics.MethodUsing monoclonal antibodies (SynTCs) that bind toxic conformations of ASyn, we utilize cellular models such as primary cortical neurons and primary astrocytes isolated from C57/BL6 mice to investigate differences in the neurotoxic effects of ASyn oligomeric strains. These differences were evaluated by both immunocytochemistry and cell‐based assays. In addition, we analyzed the thermodynamic binding occurring between SynTCs and ASyn oligomeric strains.ResultUtilizing isothermal titration calorimetry (ITC), we confirm the thermodynamic binding between SynTCs and ASyn oligomers in contrast to ASyn monomers and fibrils. Asyn oligomeric strains exhibit differential toxicity in both primary neuron and astrocyte cells. When immunodepleted by SynTCs, cytotoxicity and endogenous ASyn aggregation decreased.ConclusionInvestigating mechanisms of neurotoxicity mediated by Asyn oligomeric strains is valuable in determining biological effects and the therapeutic potential of targeting and reducing toxic ASyn oligomers that contribute to the neurotoxicity observed in multiple neurodegenerative diseases.

Plasma biomarkers combined with UPDRS and MoCA for differential assessments of amnestic cognitive impairment (aMCI), Parkinson’s disease (PD+PDD) and dementia with Lewy body (DLB): A pilot study

AbstractBackgroundThere would be tremendous value for having biomarker panels as screening tools for the assessment of AD and PD pathologies. Technologies that increase the sensitivity and accuracy of the measurement of plasma Aβ42, total Tau (t‐Tau), phosphorylated Tau (P‐tau),) have emerged and there is interest in testing plasm alpha synuclein (α‐syn). The specific aim of the present study was to assess the accuracy of plasma Aβ42, total Tau (t‐Tau), and α‐syn combined with clinical measures in identifying mild cognitive impaired (MCI), PD/PDD, and DLB cases.MethodsThe total sample size was 77 subjects including 37 NC, 16 MCI [NIA‐AA Criteria, Alberts 2011], 12PD/PDD [Hughes criteria] and 12 DLB [McKeith criteria]. NC subjects reported no demonstrable cognitive complaints, were intact functionally and cognitively.. The variables included age, education, MOCA, UPDRS, and H‐Y stage. Plasma biomarkers were assayed by ImmunoMagnetic Reduction (IMR) technology (MagQu, Inc).ResultsMOCA scores were lower in the aMCI and DLB groups. The UPDRS and H‐Y stage scores were significantly higher in the PD and DLB groups. The sensitivities using biomarkers (abeta42xT‐Tau) or MoCA individually to discriminate aMCI from NC are 0.625 to 0.92, respectively. The combination of biomarker and MoCA shows the 0.929 for the sensitivity. As to the specificity, individual biomarker or MoCA shows 0.778, whereas the combination of biomarker and MoCA shows 0.833. .When clinical measures were combined with biomarker values (UPDRS w/alpha‐syn; DLB status could be differentiated from PD/PDD with a sensitivity 0.955, Specificity 0 980, The combination of p‐tau181 with UPDRS had a sensitivity of 0.833 and specificity of 0.833 which was better than the sensitivity and specificity of the individual measures.ConclusionsInvestigations on the discrimination of DLB vs. PDD are rare. In this pilot study, we show that IMR assays of plasma α‐Syn, P‐tau 181, and Aβ42 x t‐tau in combination with clinical measures (UPDRS and MOCA), could differentiate PD/PDD from DLB, as well as NC from aMCI. Thus, our data suggest clinical utility of these novel biomarker modalities and panels. Differentiating DLB from PDD could be consequential in clinical characterization. Future studies will aim to replicate our findings on larger group sizes.

A Single Chain Fragment Variant Binding Misfolded Alpha-Synuclein Exhibits Neuroprotective and Antigen-Specific Anti-Inflammatory Properties

Alpha synuclein (αSyn) misfolding plays a requisite role in the pathogenesis of synucleinopathies. Direct toxicity to neurons, triggering neuroinflammation as well as the spreading and seeding of αSyn pathology are essential pathogenetic underlying mechanisms. Immunotherapy in experimental Parkinson's disease (PD) has been shown to be consistently effective in preclinical models, yet the initial clinical trials with monoclonal antibodies (mAbs) yielded marginal results if any. Aiming to overcome some of the limitation of this approach, we aimed to select an αSyn binding scFv antibody format and test it in multiple experimental PD in vivo models. We cloned the lead αSyn scFv based on preselection of human phage display libraries of human Fab. The selected of scFv targeting both oligomers and pre-formed fibrils (PFF) of αSyn were tested for their ability to protect neurons from triggered toxicity, influence their uptake to microglia, and accelerate misfolded αSyn degradation. The lead scFv- sMB08, was also tested for its ability to impact αSyn aggregation as well as spreading and seeding. sMB08 was shown to protect neurons from misfolded αSyn mediated toxicity, promote its intracellular degradation, and to reduce its uptake by microglia. sMB08 exhibited anti-inflammatory properties, including its ability to attenuate adaptive αSyn autoimmunity and ameliorate proinflammatory cytokine expression in brains of mice stereotactically injected with PFF. Employing three experimental models of PD, intranasal treatment with sMB08 attenuated motoric dysfunction and achieved acceptable brain levels by pharmacokinetic analysis, leading to significant preservation of dopaminergic n neurons. sMB08, a scFv targeting both αSyn oligomers and PFF, due to its small size facilitating paraneural brain penetration and avoidance of nonspecific inflammation, appears as an attractive approach to test in patients with PD by addressing the major mechanisms that mediate misfolded αSyn driven pathology.

Thiocyanate Reduces Motor Impairment in the hMPO-A53T PD Mouse Model While Reducing MPO-Oxidation of Alpha Synuclein in Enlarged LYVE1/AQP4 Positive Periventricular Glymphatic Vessels.

Parkinson's disease (PD) is due to the oxidation of alpha synuclein (αSyn) contributing to motor impairment. We developed a transgenic mouse model of PD that overexpresses the mutated human αSyn gene (A53T) crossed to a mouse expressing the human MPO gene. This model exhibits increased oxidation and chlorination of αSyn leading to greater motor impairment. In the current study, the hMPO-A53T mice were treated with thiocyanate (SCN-) which is a favored substrate of MPO as compared to chlorine. We show that hMPO-A53T mice treated with SCN- have less chlorination in the brain and show an improvement in motor skills compared to the nontreated hMPO-A53T mice. Interestingly, in the hMPO-A53T mice we found a possible link between MPO-related disease and the glymphatic system which clears waste including αSyn from the brain. The untreated hMPO-A53T mice exhibited an increase in the size of periventricular glymphatic vessels expressing the glymphatic marker LYVE1 and aquaporin 4 (AQP4). These vessels also exhibited an increase in MPO and HOCl-modified epitopes in the glymphatic vessels correlating with loss of ependymal cells lining the ventricles. These findings suggest that MPO may significantly promote the impairment of the glymphatic waste removal system thus contributing to neurodegeneration in PD. Moreover, the inhibition of MPO chlorination/oxidation by SCN- may provide a potential therapeutic approach to this disease.

Repetitive mild TBI causes pTau aggregation in nigra without altering preexisting fibril induced Parkinson’s-like pathology burden

Population studies have shown that traumatic brain injury (TBI) is associated with an increased risk for Parkinson’s disease (PD) and among U.S. Veterans with a history of TBI this risk is 56% higher. The most common type of TBI is mild (mTBI) and often occurs repeatedly among athletes, military personnel, and victims of domestic violence. PD is classically characterized by deficits in fine motor movement control resulting from progressive neurodegeneration of dopaminergic neurons in the substantia nigra pars compacta (SNpc) midbrain region. This neurodegeneration is preceded by the predictable spread of characteristic alpha synuclein (αSyn) protein inclusions. Whether repetitive mTBI (r-mTBI) can nucleate PD pathology or accelerate prodromal PD pathology remains unknown. To answer this question, an injury device was constructed to deliver a surgery-free r-mTBI to rats and human-like PD pathology was induced by intracranial injection of recombinant αSyn preformed fibrils. At the 3-month endpoint, the r-mTBI caused encephalomalacia throughout the brain reminiscent of neuroimaging findings in patients with a history of mTBI, accompanied by astrocyte expansion and microglial activation. The pathology associated most closely with PD, which includes dopaminergic neurodegeneration in the SNpc and Lewy body-like αSyn inclusion burden in the surviving neurons, was not produced de novo by r-mTBI nor was the fibril induced preexisting pathology accelerated. r-mTBI did however cause aggregation of phosphorylated Tau (pTau) protein in nigra of rats with and without preexisting PD-like pathology. pTau aggregation was also found to colocalize with PFF induced αSyn pathology without r-mTBI. These findings suggest that r-mTBI induced pTau aggregate deposition in dopaminergic neurons may create an environment conducive to αSyn pathology nucleation and may add to preexisting proteinaceous aggregate burden.

Functional Interaction Between α-Synuclein and Nurr1 in Dopaminergic Neurons

Increased expression of alpha-synuclein (ASYN) and decreased expression of Nurr1 are associated with Parkinson’s disease (PD) pathogenesis. These two proteins interact functionally and ASYN overexpression suppresses Nurr1 levels. ASYN pan-neuronal overexpression coupled with Nurr1 hemizygosity followed by Nurr1 repression in aging mice results in the manifestation of a typical PD-related phenotype and pathology. Here we investigated in mice the effects of C-terminally truncated ASYN(120) overexpression in dopaminergic (DA-ergic) neurons compounded with Nurr1 hemizygosity (‘2-hit-DA’). We report that ‘2-hit-DA’ animals did not manifest a characteristic PD-related phenotype, despite further substantia nigra ASYN-overexpression-dependent and age dependent Nurr1 protein downregulation. However, they displayed increased energy expenditure, reduced striatal dopamine (DA) and prolonged hyperactivity to a novel environment indicating impaired habituation. This DA-ergic dysfunction was observed in young adult ‘2-hit-DA’ mice, persisted throughout life and it was associated with ASYN and Nurr1 synergistic alterations of DAT levels and function. Our experiments indicate that the expression levels of ASYN and Nurr1 are critical in the dysregulation of the nigrostriatal DA system and may be involved in neuropsychiatric aspects of PD.

Dendrimers-Based Drug Delivery System: A Novel Approach in Addressing Parkinson’s Disease

Parkinson’s disease (PD) is a progressive neurodegenerative disease that is characterized by the loss of dopamine. Since dopamine has trouble entering the blood–brain barrier, the utilization of dendrimers and other nanomaterials is considered for conjugating the neurotransmitter and other PD drugs. Dendrimers are three-dimensional, hyper-branched structures that are categorized into several generations. Alpha-synuclein (ASN) is the protein involved in regulating dopaminergic functions and is the main aggregate found inside Lewy bodies. Different types of dendrimers have shown efficacy in disrupting the formation of unstable beta structures of ASN and fibrillation. The conjugation of PD drugs into nanomaterials has elicited a prolonged duration of action and sustained release of the drugs inside the BBB. The objectives of this study are to review the applications of a dendrimer-based drug delivery system in addressing the root cause of Parkinson’s disease and to emphasize the delivery of anti-Parkinson’s drugs such as rotigotine, pramipexole and dopamine using routes of administration other than oral and intravenous.

Mechanisms of NLRP3 activation and pathology during neurodegeneration.

Inflammasomes are multiprotein complexes that are mainly present in resident and infiltrating immune cells in the central nervous system. Inflammasomes function as intracellular sensors of immunometabolic stress, infection and changes in the local microenvironment. Inflammasome assembly in response to these 'danger signals', triggers recruitment and cluster-dependent activation of caspase-1 and the subsequent proteolytic activation of inflammatory cytokines such as interleukin-1β and interleukin-18. This is typically followed by a form of inflammatory cell death through pyroptosis. Since the discovery of inflammasomes in 2002, they have come to be recognized as central regulators of acute and chronic inflammation, a hallmark of progressive neurological diseases. Indeed, over the last decade, extensive inflammasome activation has been found at the sites of neuropathology in all progressive neurodegenerative diseases. Disease-specific misfolded protein aggregates which accumulate in neurodegenerative diseases, such as alpha synuclein or beta amyloid, have been found to be important triggers of NLRP3 inflammasome activation in the central nervous system. Together, these discoveries have transformed our understanding of how chronic inflammation is triggered and sustained in the central nervous system, and how it can contribute to neuronal death and disease progression in age-related neurodegenerative diseases. Therapeutic strategies around inhibition of NLRP3 activation in the central nervous system are already being evaluated to determine their effectiveness to slow progressive neurodegeneration. This review summarizes current understanding of inflammasomes in the most prevalent neurodegenerative diseases and discusses current knowledge gaps and inflammasome inhibition as a therapeutic strategy.

Phytoconstituents of Datura metel extract improved motor coordination in haloperidol-induced cataleptic mice: Dual-target molecular docking and behavioural studies

Ethnopharmacological relevanceParkinson's disease (PD) is a prominent health challenge characterized by complex aetiology and limited therapeutic breakthroughs. Datura metel (DM) is a medicinal plant containing active phytoconstituents with neuropharmacological potentials. In traditional medicine, it exerts anticholinergic, anti-inflammatory and antioxidant effects, and protection from organophosphate poisoning inclusively involved in the pharmacotherapy of PD. Its other PD-related medicinal potency includes treatment of motor sickness and bradycardia. However, the exact mechanisms of anti-PD effects of its phytoconstituents remain underexplored. Materials and methodsIn this study, methanolic extract of DM was evaluated for anti-PD behavioural effects in vivo haloperidol-induced cataleptic mice. The GC-MS-identified phytochemicals were studied for one-drug-multi-target inhibitory mechanisms against some key targets for PD treatment, alpha-synuclein (ASN) and dopa decarboxylase (DDC) using molecular docking. Resultsand discussion: Chronic administration of 50, 100 and 200 mg/kg of DM extract improved the 14-s latency time induced by haloperidol to 54, 54 and 57 s respectively, whereas levodopa (30 mg/kg) produced 47 s in rotarod tests. Similarly, the descending times for haloperidol-induced cataleptic mice were significantly reduced from 110 s to 17.7, 17.7 and 12.5 s by the respective chronic doses of DM extract, whereas levodopa-administered mice spent 17.5 s descending the same 30 cm pole. The interesting motor coordination enhancements are suggestively due to synergistic inhibition of ASN and DCC by the phytoconstituents of DM, especially, atropine and scopolamine. From the docking analysis, the two phytochemicals interacted more potently with the active therapeutic sites of the dual targets than levodopa and carbidopa. ConclusionMethanolic extract of DM contains active phytochemicals for multi-target-directed antiparkinsonian mechanisms amenable for further studies.

The Effect of Aggregated Alpha Synuclein on Synaptic and Axonal Proteins in Parkinson's Disease-A Systematic Review.

α-synuclein is a core component of Lewy bodies, one of the pathological hallmarks of Parkinson’s disease. Aggregated α-synuclein can impair both synaptic functioning and axonal transport. However, understanding the pathological role that α-synuclein plays at a cellular level is complicated as existing findings are multifaceted and dependent on the mutation, the species, and the quantity of the protein that is involved. This systematic review aims to stratify the research findings to develop a more comprehensive understanding of the role of aggregated α-synuclein on synaptic and axonal proteins in Parkinson’s disease models. A literature search of the PubMed, Scopus, and Web of Science databases was conducted and a total of 39 studies were included for analysis. The review provides evidence for the dysregulation or redistribution of synaptic and axonal proteins due to α-synuclein toxicity. However, due to the high quantity of variables that were used in the research investigations, it was challenging to ascertain exactly what effect α-synuclein has on the expression of the proteins. A more standardized experimental approach regarding the variables that are employed in future studies is crucial so that existing literature can be consolidated. New research involving aggregated α-synuclein at the synapse and regarding axonal transport could be advantageous in guiding new treatment solutions.

Skeletal Muscle is a Source of α-Synuclein with a Sarcolemmal Non-Lipid Raft Distribution.

Alpha synuclein (αSN) is a widely distributed protein in vertebrates whose physiological significance in many tissues remains unclear, being a key protein present in neurodegenerative disease such as Parkinson's Disease, Lewy Body Dementia, and in Sporadic-Inclusion Body Myositis. We search for αSN in skeletal muscle (SM) and neuronal plasma membrane isolated from brain (BR) from young and old rats. In isolated Sarcolemma from SM and from myelin-free neuronal plasma membrane isolated from BR, we determine by Western blot with anti-αSN (2B2D1) and anti-P-αSN (EP1536Y) the αSN membrane distribution, and the SM αSN intra and extracellular localization. In SM and BR, αSN is present in cytosol (CYT) as monomer and oligomer structures mainly tetramers (TM) and in plasma membranes as oligomers (TM and PM). All αSN oligomers were localized in non-lipid rafts and their distribution was unaffected by cholesterol-depletion with Methyl-β-Cyclodextrin. Membranes with natively high cholesterol content such as Transverse Tubules in SM and myelin in BR, reduce the presence of αSN. Under the same experimental conditions, aged SM and BR plasma membranes show ≈2 folds more αSN. In SM, αSN is extruded without cell damage in young and old rats. We conclude that oligomeric αSN are regularly present in SM and BR plasma membranes of healthy young and old rats. Interestingly, low-cholesterol content membranes promote αSN interaction. SM, the largest tissue in vertebrate body is a source of αSN and may contribute to the presence of αSN in extracellular fluids.

The Intranigral Infusion of Human-Alpha Synuclein Oligomers Induces a Cognitive Impairment in Rats Associated with Changes in Neuronal Firing and Neuroinflammation in the Anterior Cingulate Cortex.

Parkinson’s disease (PD) is a complex pathology causing a plethora of non-motor symptoms besides classical motor impairments, including cognitive disturbances. Recent studies in the PD human brain have reported microgliosis in limbic and neocortical structures, suggesting a role for neuroinflammation in the development of cognitive decline. Yet, the mechanism underlying the cognitive pathology is under investigated, mainly for the lack of a valid preclinical neuropathological model reproducing the disease’s motor and non-motor aspects. Here, we show that the bilateral intracerebral infusion of pre-formed human alpha synuclein oligomers (H-αSynOs) within the substantia nigra pars compacta (SNpc) offers a valid model for studying the cognitive symptoms of PD, which adds to the classical motor aspects previously described in the same model. Indeed, H-αSynOs-infused rats displayed memory deficits in the two-trial recognition task in a Y maze and the novel object recognition (NOR) test performed three months after the oligomer infusion. In the anterior cingulate cortex (ACC) of H-αSynOs-infused rats the in vivo electrophysiological activity was altered and the expression of the neuron-specific immediate early gene (IEG) Npas4 (Neuronal PAS domain protein 4) and the AMPA receptor subunit GluR1 were decreased. The histological analysis of the brain of cognitively impaired rats showed a neuroinflammatory response in cognition-related regions such as the ACC and discrete subareas of the hippocampus, in the absence of any evident neuronal loss, supporting a role of neuroinflammation in cognitive decline. We found an increased GFAP reactivity and the acquisition of a proinflammatory phenotype by microglia, as indicated by the increased levels of microglial Tumor Necrosis Factor alpha (TNF-α) as compared to vehicle-infused rats. Moreover, diffused deposits of phospho-alpha synuclein (p-αSyn) and Lewy neurite-like aggregates were found in the SNpc and striatum, suggesting the spreading of toxic protein within anatomically interconnected areas. Altogether, we present a neuropathological rat model of PD that is relevant for the study of cognitive dysfunction featuring the disease. The intranigral infusion of toxic oligomeric species of alpha-synuclein (α-Syn) induced spreading and neuroinflammation in distant cognition-relevant regions, which may drive the altered neuronal activity underlying cognitive deficits.

Multiple checkpoints of protein clearance machinery are modulated by a common microRNA, miR-4813-3p, through its putative target genes: Studies employing transgenic C. elegans model

In order to maintain cellular homeostasis and a healthy state, aberrant and aggregated proteins are to be recognized and rapidly cleared from cells. Parkinson's disease, known to be associated with multiple factors; presents with impaired clearance of aggregated alpha synuclein as a key factor. We endeavored to study microRNA molecules with potential role on regulating multiple checkpoints of protein quality control within cells. Carrying out global miRNA profiling in a transgenic C. elegans model that expresses human alpha synuclein, we identified novel miRNA, miR-4813-3p, as a significantly downregulated molecule. Further studying its putative downstream target genes, we were able to mechanistically characterize six genes gbf-1, vha-5, cup-5, cpd-2, acs-1 and C27A12.7, which relate to endpoints associated with alpha synuclein expression, oxidative stress, locomotory behavior, autophagy and apoptotic pathways. Our study reveals the novel role of miR-4813-3p and provides potential functional characterization of its putative target genes, in regulating the various pathways associated with PQC network. miR-4813-3p modulates ERUPR, MTUPR, autophagosome-lysosomal-pathway and the ubiquitin-proteasomal-system, making this molecule an interesting target for further studies towards therapeutically addressing multifactorial aspect of Parkinson's disease.

In vivo and autopsy validation of alpha-synuclein seeding activity using RT-QuIC assay in the gastrointestinal tract of patients with Parkinson's disease

ObjectiveIn the present study, real-time quaking-induced conversion (RT-QuIC) assay was used to evaluate pathologic alpha-synuclein (AS) seeding activity in formalin-fixed paraffin-embedded (FFPE) tissue from the gastrointestinal (GI) tract of Parkinson's disease (PD) patients. MethodsThis study was conducted in two parts: Part I. a preliminary autopsy study that included four autopsy-confirmed patients with synucleinopathy (2 PD, 1 dementia with Lewy bodies [DLB], and 1 multiple system atrophy [MSA]) and two normal autopsy controls. Frozen and FFPE tissues of the brain were obtained. Part II. a clinical case-control study that included 20 clinically diagnosed PD patients and matched controls. Surgically resected FFPE tissues from the upper and lower GI tracts were used. The RT-QuIC assay was performed to evaluate pathologic seed amplification using frozen or FFPE tissues. The presence or absence of AS aggregation was confirmed by conventional phosphorylated AS (pAS) immunohistochemistry (IHC). ResultsIn Part I, RT-QuIC assay showed pathologic AS amplification in frozen and FFPE brain tissues of PD and DLB patients, and FFPE stomach tissue of PD patients but not in the MSA patient and controls. In Part II, pathologic seeding activity was found in 10% (2/20) of the stomach tissues of clinical PD patients but in none of the matched controls. IHC showed pAS-positive staining in 55% of patients (11/20) and 15% of controls (3/20). ConclusionThe present study results showed that the RT-QuIC assay using FFPE tissue of the GI tract was inadequate as a biomarker in PD.

Herbal Moieties and its effect on Parkinsonism: A New Prospective

Parkinson’s disease is a brain disease that leads to stiffness, shaking, and problems with walking, balance of coordination, and brain injury. It occurs when nerve cells or neurons that produce an important brain channel known as dopamine and control the movements in an area of the brain is impaired and die. Parkinson’s symptoms usually begin gradually and get worse over times. Age is the one clear risk factor for this disease. A person with Parkinson’s disease may have clumps of proteins known as alpha synuclein or Lewy bodies in their brain. There is no cure for Parkinson’s disease, the aim of medical management of Parkinson’s disease to restore the proper balance of dopaminergic and cholinergic activities in the brain in order to relieve symptoms. This review presents a brief overview of scientific basis that support the plant derived natural products and their constituents for the treatment of underlying neuronal degeneration observed in Parkinson’s disease. The neuroprotective effects exhibited by these medicinal plants and their constituents are considered to be due to their ability to modulate; glutathione, superoxide dismutase and catalase in the brain, which all are disrupted in the PD brain. Keywords: PD, Indian Herbs

Translocation of Distinct Alpha Synuclein Species from the Nucleus to Neuronal Processes during Neuronal Differentiation.

Alpha synuclein (aSyn) and its aggregation are crucial for the neurodegeneration of Parkinson’s disease (PD). aSyn was initially described in the nucleus and presynaptic nerve terminals. However, the biology of nuclear aSyn and the link of aSyn between subcellular compartments are less understood. Current knowledge suggests the existence of various aSyn species with distinct structural and biochemical properties. Here, we identified a C-terminal-targeting aSyn antibody (Nu-aSyn-C), which has a high immunoaffinity towards aSyn in the nucleus. Comparing the Nu-aSyn-C antibody to aSyn antibodies developed against phosphorylated or aggregated forms, we observed that nuclear aSyn differs from cytosolic aSyn by an increased phosphorylation and assembly level in proliferating cells. Employing Nu-aSyn-C, we characterized aSyn distribution during neuronal differentiation in midbrain dopaminergic neurons (mDANs) derived from human-induced pluripotent stem cells (hiPSCs) and Lund human mesencephalic cells, and in primary rat hippocampal neurons. We detected a specific translocation pattern of aSyn during neuronal differentiation from the nucleus to the soma and finally to neuronal processes. Interestingly, a remarkable shift of Nu-aSyn-C-positive species towards neurites was detected in hiPSC mDANs from a PD patient carrying aSyn gene duplication. Together, our results reveal distinct nuclear and cytosolic aSyn species that redistribute during neuronal differentiation—a process that is altered in PD-derived neurons.

Microbial DNA globular liquid crystal like deposits inside Lewy bodies in four Lewy dementia patients

Four autopsy brains demonstrated concurrent evidence of Diffuse Cortical Lewy Body Dementia and active Lyme neuroborreliosis in adjacent brain sites. Lewy bodies In DCLBD contain microbial DNA. Alpha Synuclein proteins, which intrinsically bind to human nuclear DNA also bind to microbial DNa deposits inside Lewy bodies in the cytoplasmic compartment of diseased neurons. This is the first report of an association between spirochetal brain infection and Lewy Body Dementia.