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[Display omitted] Synucleins are pivotal in neurodegenerative conditions. Beta-synuclein (β-synuclein) is part of the synuclein protein family alongside alpha-synuclein (α-synuclein) and gamma-synuclein (γ-synuclein). These proteins, found mainly in brain tissue and cancers, are soluble and unstructured. β-synuclein shares significant similarity with α-synuclein, especially in their N -terminus, with a 90% match. However, their aggregation tendencies differ significantly. While α-synuclein aggregation is believed to be counteracted by β-synuclein, which occurs in conditions like Parkinson's disease, β-synuclein may counteract α-synuclein's toxic effects on the nervous system, offering potential treatment for neurodegenerative diseases. Under normal circumstances, β-synuclein may guard against disease by interacting with α-synuclein. Yet, in pathological environments with heightened levels or toxic substances, it might contribute to disease. Our research aims to explore potential harmful mutations in the β-synuclein using computational tools to predict their destabilizing impact on protein structure. Consensus analysis revealed rs1207608813 (A63P), rs1340051870 (S72F), and rs1581178262 (G36C) as deleterious. These findings highlight the intricate relationship between nsSNPs and protein function, shedding light on their potential implications in disease pathways. Understanding the structural consequences of nsSNPs is crucial for elucidating their role in pathogenesis and developing targeted therapeutic interventions. Our results offer a robust computational framework for identifying neurodegenerative disorder-related mutations from SNP datasets, potentially reducing the costs associated with experimental characterization. [ABSTRACT FROM AUTHOR]

• aSyn density is similar in both submandibular glands of autopsied patients with Parkinson's disease. • Parkinson's disease duration correlated with submandibular gland aSyn density. • There was no evidence for significant tissue damage in previously biopsied submandibular glands. Peripheral tissue biopsy in Parkinson's disease (PD) may be valuable for clinical care, biomarker validation, and as research enrollment criteria. Determine whether submandibular gland pathologic alpha-synuclein (aSyn) density is symmetrical and whether previous needle biopsy caused tissue damage. Thirty autopsy-confirmed PD cases having fixed submandibular gland tissue from one side and frozen submandibular gland tissue from the contralateral side were studied. Tissue was stained for phosphorylated aSyn and density (0–4 semiquantitative scale) was determined. Three previously biopsied cases were also assessed for tissue damage at subsequent autopsy. Mean (SD) age was 80.9 (5.5) years and disease duration 12.5 (9.3). Submandibular gland aSyn staining had a mean score of 2.13 for both the initially fixed and the initially frozen submandibular glands. The correlation between aSyn density of the two sides was r = 0.63. Correlation of aSyn density, in the originally fixed submandibular gland, with disease duration was good (r = 0.49, p =.006). No permanent tissue damage was found in the three previously biopsied cases. This study found good correlation between aSyn density in both submandibular glands of patients with PD and found no evidence of significant tissue damage in previously biopsied subjects. [ABSTRACT FROM AUTHOR]

• α7 nAChR activation showed the neuroprotective effect. • α7 nAChR activation reduced the intracellular aggregates of α-Synuclein. • α7 nAChR activation by PNU282987 promotes TFEB activity. • PNU282987 reduces the intracellular α-Synuclein via the upregulation of autophagy. • Activation of α7 nAChR may possess novel therapeutic potential for PD. The α7 neuronal nicotinic acetylcholine receptor (α7 nAChR) is a potential target for the development of Parkinson's disease (PD) therapeutics. α-Synuclein (α-Syn), a principal component of Lewy bodies (cytoplasmic inclusions), is a major contributor to PD pathophysiology. Previous studies have demonstrated that activating α7 nAChR protects against nigrostriatal dopamine degeneration in acute and chronic PD animal models induced by 6-hydroxydopamine and rotenone, respectively. In the present study, we investigated the effects of PNU282987, a selective α7 nAChR agonist, against α-Syn-induced neurotoxicity in α-SynWT-, α-SynA30P-, and α-SynE46K-N2a cells. PNU282987 exhibited substantial neuroprotection against both wild-type and mutant-type α-Syn-induced toxicity. Furthermore, PNU282987 promoted transcription factor EB activity and reduced intracellular α-Syn protein levels through autophagy induction. These results highlight the therapeutic potential of α7 nAChR activation in diseases characterized by α-Syn aggregation, such as PD. [ABSTRACT FROM AUTHOR]

Dementia with Lewy Bodies (DLB) is a common neurodegenerative disorder of the aging population characterized by α-synuclein accumulation in cortical and subcortical regions. Although neuropathology in advanced age has been investigated in dementias such as Alzheimer Disease (AD), severity of the neuropathology in the oldest old with DLB remains uncharacterized. For this purpose we compared characteristics of DLB cases divided into three age groups 70-79, 80-89 and ≥ 90 years (oldest old). Neuropathological indicators and levels of synaptophysin were assessed and correlated with clinical measurements of cognition and dementia severity. These studies showed that frequency and severity of DLB was lower in 80-89 and ≥ 90 year cases compared to 70-79 year old group but cognitive impairment did not vary with age. The extent of AD neuropathology correlated with dementia severity only in the 70-79 year group, while synaptophysin immunoreactivity more strongly associated with dementia severity in the older age group in both DLB and AD. Taken together these results suggest that the oldest old with DLB might represent a distinct group.

[Display omitted] • Misfolded proteins such as α-synuclein in PD, and β-amyloid in AD usually insult microglial overactivation, comparison of the extent of microglial activation under treatments with exogenous pathological proteins may provide a better understanding of microglial inflammation in neurodegenerative diseases. • The PRAK plays an important role in microglial activation and serves as an intersection in conformationally different α-synuclein in activating microglia. • EVs from microglia treated with monomeric α-synuclein could promote anti-inflammatory microglia and most of the changed EVs-associated miRNAs targeted PRAK. • The application of PRAK inhibitor GLPG0259 in combination with EVs+ may pave the way for mitigating neuroinflammation. Parkinson's disease (PD) is characterized by the formation of Lewy body, which mainly contains misfolded α-synuclein. Microglial activation plays a role in neurodegeneration. The pathologically oligomeric α-synuclein promotes inflammatory microglia, while physiologically monomeric α-synuclein induces anti-inflammatory microglia, the relationship between these two forms in activating microglia and the molecular mechanism is essentially unknown. In this study, using in vivo and in vitro models, we challenged primary or BV2 microglia with exogenous stimuli including α-synuclein. We examined microglial activation and the underlying mechanism by Western blot, RT-PCR, ELISA, IF, FCM, miRNA sequencing and bioinformatic analysis. Oligomeric α-synuclein activated microglia via the involvement of the PRAK/MK5 pathway. The specific PRAK inhibitor GLPG0259 could mitigate microglial activation insulted by oligomeric α-synuclein. Monomeric α-synuclein regulated the anti-inflammatory microglia by delivering microglia-derived extracellular vesicles (EVs) in vitro and in vivo. Further sequencing and bioinformatic analysis of microglial EVs-associated miRNAs indicated that most of these miRNAs targeted PRAK. These results suggest that PRAK serves as an intersection in microglial activation when challenged with conformationally different α-synuclein. EVs derived from microglia treated with monomeric α-synuclein promote anti-inflammatory microglia by delivering miRNAs that target PRAK into recipient microglia. [ABSTRACT FROM AUTHOR]

• Currently no in vitro model recapitulating both dopamine neuron loss and aSyn aggregation. • First study to study the effect of PFF + 6-OHDA in primary midbrain cultures. • 6-OHDA results in dopamine neuron loss in primary midbrain cultures. • aSyn PFFs did not cause dose-dependent loss of TH-positive dopamine neurons in culture. • Optimized PFF + 6-OHDA primary midbrain cultures can be promising model for drug screening. Parkinson's disease (PD) is characterized by the loss of nigrostriatal dopamine (DA) neurons and the presence of alpha-synuclein (αSyn)-positive Lewy body (LB) pathology. In this study, we attempted to recapitulate both these features in a novel in vitro model for PD. To achieve this, we combined the αSyn pre-formed fibril (PFF)-seeded LB-like pathology with 6-hydroxydopamine (6-OHDA)-induced mitochondrial toxicity in mouse embryonic midbrain cultures. To pilot the model for therapeutics testing, we assessed the effects of cerebral dopamine neurotrophic factor (CDNF) on αSyn aggregation and neuron survival. PFF-seeded pathology did not lead to DA neuron loss even with the highest dose of PFFs. The combination of PFFs and 6-OHDA did not trigger additional neurodegeneration or LB–like pathology and instead presented DA neuron loss to a similar extent as with 6-OHDA only. CDNF did not affect the PFF-seeded αSyn pathology or the DA neuron survival in the combination model but showed a trend toward neuroprotection in the 6-OHDA-only cultures. [ABSTRACT FROM AUTHOR]

• Overexpression of α-syn in the hippocampal neuronal nuclei led to anxiety-like behavior in mice. • Nuclear localization of α-syn activated NG2 glial cells and promotes the synthesis and release of GABA in the hippocampus. • Nuclear localization of α-syn induced the loss of neurotrophic factors, and decreased neurogenesis. • α-syn diffused to the amygdala resulting in pathologic accumulation of α-syn and gliosis and caused loss of interneurons. Fear and anxiety are common in Parkinson's disease (PD) and may be caused by pathologies outside the dopaminergic system. Increasing evidence has shown that alpha-synuclein (α-syn) is involved in the development of anxiety in PD. In this study, we examined the effects of α-syn nuclear translocation on anxiety-like behavior in mice by overexpressing α-syn in the nuclei of the cell in the hippocampus. Our results show that α-syn overexpression in the nuclei increased the excitability of hippocampal neurons and activated NG2 glial cells and promoted the synthesis and release of γ-aminobutyric acid (GABA). And nuclear localization of α-syn led to the loss of neurotrophic factors and decreased neurogenesis. Meanwhile, the hippocampus and amygdala acted synergistically, resulting in pathologic accumulation of α-syn and gliosis in the amygdala and caused loss of interneurons. These events led to the impairments of hippocampus and amygdala function, which ultimately induced anxiety-like behavior in mice. The findings obtained in our present study indicate that excessive nuclear translocation of α-syn in hippocampal neurons and damage to the amygdala circuits may be important in the development of anxiety in PD. [ABSTRACT FROM AUTHOR]

• The GG genotype at SNCA rs11931074 significantly reduces the risk of PD. • The GG genotype at SNCA rs11931074 significantly increases risk of dementia in PD. • Older age, higher UPDRS III score and fewer years of education are associated with higher risk of dementia in PD. Single-nucleotide polymorphisms (SNPs) in the SNCA gene encoding alpha-synuclein have been shown to affect the PD phenotype. However, whether such polymorphisms can influence risk of dementia in PD remains unclear. To investigate possible associations between SNCA gene polymorphisms and dementia in patients with PD. A consecutive series of 291 PD patients with dementia (n = 45, 15.5%) or without it (n = 246, 84.5%) were genotyped at four SNPs in the SNCA gene. As controls, 615 healthy Han Chinese were also genotyped. Three SNPs (rs11931074, rs7684318 and rs356219) were in strong linkage disequilibrium. The GG genotype at rs11931074 significantly reduced risk of PD (p = 0.023), but it significantly increased risk of dementia after PD onset (p = 0.015) based on the recessive genetic model. Logistic regression identified the following risk factors for dementia among patients with PD: age ≥65 years (odds ratio [OR] 2.69, 95% confidence interval [CI] 1.25–5.77, p = 0.011), education ≤6 years (OR 4.66, 95% CI 2.21–9.83, p < 0.001), part III score on the Unified Parkinson's Disease Rating Scale ≥40 (OR 5.01, 95% CI 2.40–10.45, p < 0.001), and GG genotype at rs11931074 (OR 2.81, 95% CI 1.16–6.83, p = 0.022). PD patients carrying the protective GG genotype at SNCA rs11931074 may be at significantly higher risk of dementia than patients with other genotypes. Our results support the view that SNCA polymorphisms can have opposite effects on preclinical and clinical PD. [ABSTRACT FROM AUTHOR]

• Naturally occurring autoantibodies against human α-Syn (nAbs α-Syn) were detected in the peripheral blood of PD patients and controls in different levels. • We investigated the inhibitory effect of nAbs α-Syn on distinct α-Syn fragments induced inflammation and cytotoxicity on pr0imary microglia. • All α-Syn fragments induced the release of the pro-inflammatory cytokines interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α) from primary cultured microglia. • Cotreatment with nAbs α-Syn did alleviate the release of pro-inflammatory cytokines induced by the α-Syn fragments α-Syn 1–95, α-Syn 61–140, α-Syn 96–140 and α-Syn 112. • Treatment with the α-Syn fragments α-Syn 1–95, α-Syn 61–140 and α-Syn 112 impaired the viability of primary microglia. This effect could not be counteracted by cotreatment with nAbs α-Syn. Alpha-synuclein (α-Syn) is a soluble protein primarily expressed in presynaptic terminals in the central nervous system (CNS). Aggregates of fibrillated α-Syn are the major component of Lewy bodies (LB), a pathologic hallmark of idiopathic Parkinson's disease (PD). Recently, naturally occurring autoantibodies against human α-Syn (nAbs α-Syn) were detected in the peripheral blood of PD patients and controls. Here, we investigated the inhibitory effects of nAbs α-Syn on distinct α-Syn fragments, as well as inflammatory responses and cytotoxicity evoked by nAbs α-Syn in primary microglia. All α-Syn fragments induced the release of the pro-inflammatory cytokines interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α) from microglia in primary culture. Cotreatment with nAbs α-Syn alleviated the release of pro-inflammatory cytokines induced by α-Syn fragments α-Syn 1–95, α-Syn 61–140, α-Syn 96–140 and α-Syn 112. Treatment with the α-Syn fragments α-Syn 1–95, α-Syn 61–140 and α-Syn 112 impaired the viability of primary microglia. This effect could not be counteracted by cotreatment with nAbs α-Syn. Data suggest an important role of nAbs α-Syn in the α-Syn-induced inflammation cascade, and indicate the potential importance of nAbs in the pathogenesis of PD. This could provide an experimental therapeutic target for patients with PD. [ABSTRACT FROM AUTHOR]

• Nitrated α-SYN is an undesirable modification associated with oxidative and nitrative damage. • Positive nitrated α-SYN immunostaining in minor salivary gland was observed in all patients but not in control group. • The nitrated alpha-synuclein positive structures were located in periacinar stroma in PD. • Nitrated α-SYN exists in the early stage and is probably a promising biomarker for PD. Alpha-synuclein (α-SYN) is found in peripheral autonomic neuronal network apart from brain in Parkinson's disease (PD). Nitrated α-SYN is an undesirable modification associated with oxidative and nitrative damage and has been found extensively in brain, gastrointestinal(GI) tract and blood cells in PD. We aim to investigate the presence of nitrated α-SYN in minor salivary gland biopsy in PD. Patients with PD and age-matched controls underwent minor salivary gland biopsy. Motor impairment was assessed by Hoehn-Yahr (H-Y) stage and Unified Parkinson's Disease Rating Scale (UPDRS) Part III in off-state. 11C-methyl -N- 2b-carbomethoxy-3b-(4-fluorophenyl) tropane (11C-CFT) DAT-PET scan was performed in all subjects. Immunohistochemical staining for nitrated α-SYN was performed in the minor salivary gland tissues. The minor salivary gland tissues of 8 PD cases and 7 controls with early stage (H-Y stage 1-2) were detected. All PD patients showed asymmetrical and reduction of 11C-CFT uptake in the caudate, anterior and posterior putamen, while all control subjects showed normal DAT-PET scan. Positive nitrated α-SYN immunostaining was observed in all PD patients (8/8,100%) but not in control subjects (0/7). The results were consistent well with that of DAT-PET. These nitrated alpha-synuclein positive structures were mainly located in the periacinar stroma in PD patients. Our result suggests that nitrated α-SYN exists in the early stage and is probably a promising biomarker for PD. Minor salivary gland is an ideal site for α-SYN nitration detection. Despite of the small number of subjects, attention should be given to α-SYN nitration in PD and more investigations on nitrated α-SYN in different sites and large sample using should be explored in future. [ABSTRACT FROM AUTHOR]

Highlights • Aggregated species of α-SN are crucial factors to pathogenicity of dopaminergic cell. • The response of different cell models is dissimilar facing with α-SN aggregates. • The viability rate was significantly lower in PC12 than PHNs in response to α-SN. • The intracellular ROS and Ca2+ levels were significantly increased in both cells in response to α-SN. Abstract Background Alpha-synuclein (αSN) is an abundant presynaptic brain protein that its aggregated species believed to play pivotal roles in the development of neurodegenerative diseases, especially Parkinson's disease (PD). In this study, we compared the response of primary neuronal cells with a well-known cell line model, PC12, against the toxic aggregates of αSN. Methods Primary hippocampal neurons (PHNs) were isolated from 17 to 18 days old rat embryos. Fibrillization was induced in recombinant αSN and monitored by standard methods. The toxicity of different aggregates of αSN on the treated cells was then studied. Furthermore, changes in the intracellular reactive oxygen species (ROS) and Ca2+ levels were also compared in two kinds of treated cells. We also studied the gene expression profile of certain Ca2+ channels and carriers using the GEO2 database. Results The viability rate was significantly lower in PC12 versus PHNs, in response to αSN. This is while the intracellular ROS and Ca2+ levels were significantly increased in both cell types. Analysis of microarray data indicated that some factors involved in Ca2+ hemostasis may face significant changes in the PD condition. Conclusion By putting these data together, it is clear that PHN is more resistant than PC12 toward αSN cytotoxicity even in the presence of rising cytoplasmic ROS and Ca2+ levels. Exploring the supporting mechanisms which PHN uses to be more resistant to αSN cytotoxicity can help to open a roadmap toward therapeutic plans in PD and other synucleinopathy disorders. [ABSTRACT FROM AUTHOR]

• SGK1 levels were reduced and α-synuclein levels were increased in the skeletal muscle of PD mice. • Knockdown of SGK1 in C2C12 cells led to increased α-synuclein expression. • The decrease in SGK1 could potentially contribute to PD by increasing α-synuclein expression in skeletal muscle. Parkinson's disease (PD) is a neurodegenerative disease caused by loss of dopaminergic neurons in the substantia nigra and it is known to involve the accumulation of α-synuclein (α-syn), which is a neuroprotein that promotes degeneration of dopaminergic neurons. Serum/glucocorticoid-related kinase 1 (SGK1) is involved in the physiological and pathological processes in neurons. The aim of this study was to examine the relationship between SGK1 and α-syn expression in muscle tissue of a PD model and in C2C12 cells. Western blotting, immunohistochemistry, and immunofluorescence microscopy confirmed reduced SGK1 and increased α-syn expression in skeletal muscle of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated mice compared to the control group. To determine the relationship between SGK1 and α-syn, SGK1 small interfering RNA (siRNA) knockdown was performed in C2C12 cells, which showed that suppression of SGK1 levels resulted in increased α-syn expression. The main finding of our study is that reduction of SGK1 expression contributes to the pathogenesis of PD by increasing the expression of α-syn in skeletal muscle of MPTP-treated mice and C2C12 cells. This study confirms that decreased SGK1 induces increased α-syn expression in skeletal muscle, which suggests that maintaining SGK1 expression may improve PD symptoms. [ABSTRACT FROM AUTHOR]

Alpha-Synuclein (α-Syn) is an important protein in the pathogenesis of Parkinson disease (PD) as it accumulates as fibrillar inclusions in affected brain regions including dopaminergic neurons in the substantia nigra. Elevated levels of α-Syn seem to be crucial in mediating its toxicity. Thus, detailed information regarding the regulatory mechanism of α-Syn expression in several layers such as transcription, post-transcription and post-translation is needed in order to devise therapeutic interventions for PD. Previously, we reported that expression of α-Syn is repressed by microRNA-7 (miR-7) through its effect on the 3′-untranslated region (UTR) of α-Syn mRNA. Here, we show that miR-7 also accelerates the clearance of α-Syn and its aggregates by promoting autophagy in differentiated ReNcell VM cells. Further, miR-7 facilitates the degradation of pre-formed fibrils of α-Syn transported from outside the cells. This additional mechanism for reducing α-Syn levels show miR-7 to be an important molecular target for PD and other alpha-synucleinopathies. [ABSTRACT FROM AUTHOR]

The relationship between cerebrospinal fluid (CSF) proteins and brain function in Parkinson’s disease (PD) is not explained clearly. We investigated the correlations between CSF proteins and spontaneous neuronal activity in PD patients via fractional amplitude of low-frequency fluctuation (fALFF) using the Parkinson’s Progression Markers Initiative database. Twenty-eight PD patients underwent resting-state functional magnetic resonance imaging in “off” status and lumbar puncture within a month. Correlation analyses between CSF proteins and fALFF value in whole brain as well as clinical assessment scores were performed. We found CSF total tau (t-tau) level was negatively correlated with fALFF in posterior cingulate gyrus. And fALFF in posterior cingulate gyrus was positively correlated with Hopkins Verbal Learning Test-Revised recognition discrimination index. Besides, alpha-synuclein (α-syn) level was correlated with fALFF in bilateral inferior frontal gyrus. This study provides evidence that CSF proteins may have a relationship with brain function related to cognitive status in PD patients. [ABSTRACT FROM AUTHOR]

Background The p. A53T mutation in the alpha-synuclein ( SNCA ) gene is a rare cause of autosomal dominant Parkinson’s disease (PD). Although generally rare, it is particularly common in the Greek population due to a founder effect. A53T-positive PD patients often develop dementia during disease course and may very rarely present with dementia. Methods We screened for the p. A53T SNCA mutation a total of 347 cases of Greek origin with parkinsonism and/or dementia, collected over 15 years at the Neurogenetics Unit, Eginition Hospital, University of Athens. Cases were classified into: “pure parkinsonism”, “pure dementia” and “parkinsonism plus dementia”. Results In total, 4 p. A53T SNCA mutation carriers were identified. All had autosomal dominant family history and early onset. Screening of the “pure parkinsonism” category revealed 2 cases with typical PD. The other two mutation carriers were identified in the “parkinsonism plus dementia” category. One had a diagnosis of PD dementia and the other of behavioral variant frontotemporal dementia. Screening of patients with “pure dementia” failed to identify any further A53T-positive cases. Conclusions Our results confirm that the p. A53T SNCA mutation is relatively common in Greek patients with PD or PD plus dementia, particularly in cases with early onset and/or autosomal dominant family history. [ABSTRACT FROM AUTHOR]

Background Variations of α-synuclein levels or species have been reported in Parkinson’s Disease (PD). There has been little systematic examination of erythrocytes, a rich source of α-synuclein. Methods Erythrocyte membranes were obtained from PD patients (mutation carriers in the α-synuclein gene (A53T-PD) and glucocerebrosidase gene (GBA-PD) (n = 18 each), and patients without known mutations (GU-PD, n = 56)), and age-/sex-matched controls (n = 56). Levels of monomeric and dimeric α-synuclein were assessed using Western immunoblotting. Results A statistically significant increase of α-synuclein dimer and dimer to monomer ratio was found in GBA-PD and GU-PD. In contrast, dimer levels of A53T-PD were not different from controls. No difference was found in α-synuclein monomer levels. Conclusions The increased α-synuclein dimer in GBA-PD and GU-PD is suggestive of an apparent systemic dysfunction causing the dimerization, and potentially oligomerization, of α-synuclein. These results may have implications for PD pathogenesis and biomarker development. [ABSTRACT FROM AUTHOR]

Proteinopathies constitute a diverse group of devastating neurodegenerative disorders, characterized by aberrant aggregation of specific proteins within neurons and in the brain parenchyma. Parkinson’s disease (PD) is among the most common proteinopathies, caused by the accumulation of different species of α-synuclein and the formation of protein inclusions known as Lewy bodies. Although several mutations in the α-synuclein gene have been linked to PD, the mechanisms mediating the aggregation and toxicity of α-synuclein are not fully understood. Here, we review recent evidence that highlight an intricate interplay between α-synuclein and ionostasis, focusing on the PMR1 pump, a Golgi resident Ca 2+ /Mn 2+ P-type ATPase, which plays a pivotal role in regulating the intracellular levels of calcium and manganese ions. [ABSTRACT FROM AUTHOR]

The conversion of α-synuclein from its natively unfolded and α-helical tetrameric forms to an amyloid conformation is central to the emergence of Parkinson’s disease. Therefore, prevention of this conversion may offer an effective way of avoiding the onset of this disease or delaying its progress. At different concentrations, an aqueous extract from the edible winged kelp ( Alaria esculenta ), was shown to lower and to raise the melting point of α-synuclein. Size fractionation of the extract resulted in the separation of these distinct activities. The fraction below 5 kDa decreased the melting point of α-synuclein, whereas the fraction above 10 kDa raised the melting point. Both of these fractions were found to inhibit the formation of amyloid aggregates by α-synuclein, measured by thioflavin T dye-binding assays; this effect was further confirmed by transmission electron microscopy showing the inhibition of fibril formation. Circular dichroism analysis suggested that the incubation of α-synuclein under fibrillation conditions resulted in the loss of substantial native helical structure in the presence and absence of the fractions. It is therefore likely that the fractions inhibit fibrillation by interacting with the unfolded form of α-synuclein. [ABSTRACT FROM AUTHOR]

Lewy bodies and neurites, the pathological hallmarks found in the brain of Parkinson’s disease (PD) patients, are primarily composed of aggregated and hyperphosphorylated alpha-synuclein. The observation that alpha-synuclein inclusions are also found in the gut of the vast majority of parkinsonian patients has led to an increasing number of studies aimed at developing diagnostic procedures based on the detection of pathological alpha-synuclein in gastrointestinal biopsies. The previous studies, which have all used immunohistochemistry for the detection of alpha-synuclein, have provided conflicting results. In the current survey, we used a different approach by analyzing the immunoreactivity pattern of alpha-synuclein separated by one- and two-dimensional electrophoresis, in colonic biopsies from PD subjects and healthy individuals. We did not observe any differences between controls and PD in the expression levels, phosphorylation or aggregation status of alpha-synuclein. Overall, our study suggests that the two biochemical methods tested here are not adequate for the prediction of PD using gastrointestinal biopsies. Further studies, using other biochemical approaches, are warranted to test whether there exists specific forms of pathological alpha-synuclein that distinguish PD from control subjects. [ABSTRACT FROM AUTHOR]

Introduction Amongst Parkinson's disease (PD) genetic factors, mutations in LRRK2 , SNCA , VPS35 and GBA genes are recognized causes of PD. Nonetheless, few genetic screenings have been conducted in families with a history of PD consistent with autosomal dominant inheritance (ADPD), and their relevance to the etiology of PD has been poorly explored in Latin American populations, such as the Brazilian one, with a high degree of admixture. Methods In order to assess the contribution of specific mutations in LRRK2, SNCA , VPS35 and GBA genes to ADPD in Brazil, we conducted the first molecular evaluation in a cohort of 141 index cases from families with ADPD. Genomic DNA was isolated from peripheral blood or saliva, and the molecular analysis was performed by TaqMan allelic discrimination assays or bidirectional sequencing. Results Heterozygous mutations in LRRK2 and GBA genes were identified in 10 (7.0%) probands, and all presented typical signs of classical PD. No mutations were found in SNCA or VPS35 genes. Conclusion Our findings in a representative series of index cases from families with ADPD emphasize the important contribution of LRRK2 G2019S and GBA (L444P and N370S) mutations to parkinsonism in Brazilian families. The absence of mutations in VPS35 and SNCA genes reveals that they are uncommon causes of PD in Brazil, corroborating previous studies that also failed to detect these genetic variants in PD patients from other populations. Recent discoveries of novel causative genes of autosomal dominant forms of PD expand the investigative possibilities and should be targeted on future studies. [ABSTRACT FROM AUTHOR]

Problems with attention and short-term learning and memory are commonly reported after mild traumatic brain injury (mTBI). Due to the known relationships between α-synuclein ( SNCA ), dopaminergic transmission, and neurologic deficits, we hypothesized that SNCA polymorphisms might be associated with cognitive outcome after mTBI. A cohort of 91 mTBI patients one month after injury and 86 healthy controls completed a series of cognitive tests assessing baseline intellectual function, attentional function, and memory, and was genotyped at 13 common single nucleotide polymorphisms (SNPs) in the SNCA gene. Significant differences in two memory measures (p = 0.001 and 0.002), but not baseline intellectual function or attentional function tasks, were found between the mTBI group and controls. A highly significant protective association between memory performance and SNCA promoter SNP rs1372525 was observed in the mTBI patients (p = 0.006 and 0.029 for the long and short delay conditions of the California Verbal Learning Tests, respectively), where the presence of at least one copy of the A (minor) allele was protective after mTBI. These results may help elucidate the pathophysiology of cognitive alterations after mTBI, and thus warrant further investigation. [ABSTRACT FROM AUTHOR]

Activating transcription factor 4 (ATF4) is a member of the PERK signaling pathway, which directly binds endoplasmic reticulum stress target genes and plays a crucial role in both adaptations to stress and activation of apoptosis. Previous publications demonstrated conflicting evidence on the role of ATF4 in the pathogenesis of neurodegenerative disorders. In this study, we used recombinant adeno-associate virus (rAAV)-mediated gene transfer to investigate if the sustained up-regulation of ATF4 launches a pro-survival or pro-death trend in the dopamine (DA) cells of the substantia nigra pars compacta in a rat model of Parkinson-like neurodegeneration induced by human alpha-synuclein (αS) overexpression. We showed that ATF4 does not protect nigral DA neurons against an αS-induced pathology. Moreover, the rAAV-mediated overexpression of ATF4 resulted in severe nigra-striatal degeneration via activation of caspases 3/7. [ABSTRACT FROM AUTHOR]

Vocal communication deficits are common in Parkinson disease (PD). Widespread alpha-synuclein pathology is a common link between familial and sporadic PD, and recent genetic rat models based on familial genetic links increase the opportunity to explore vocalization deficits and their associated neuropathologies. Specifically, the Pink1 knockout (-/-) rat presents with early, progressive motor deficits, including significant vocal deficits, at 8 months of age. Moreover, this rat model exhibits alpha-synuclein pathology compared to age-matched non-affected wildtype (WT) controls. Aggregations are specifically dense within the periaqueductal gray (PAG), a brainstem region involved in the coordination of emotional and volitional control of vocalizations. Here, we investigated changes in gene expression within the PAG at 8 months of age in Pink1 −/- rats compared to WT. Our data demonstrate that Pink1 -/- rat mRNA expression levels of alpha-synuclein are comparable to WT. However, Pink1 -/- rats show significantly decreased levels of Atp13a2 , a transmembrane lysosomal P5-type ATPase suggesting a potential mechanism for the observed abnormal aggregation. We found no difference in the expression of glucocerebrosidase ( Gba ) or the CASP8 and FADD-like apoptosis regulator ( Cflar ). Further, we show that mRNA expression levels of dopaminergic markers including Th , D1 and D2 receptor as well as GABA signaling markers including Gaba-A and glutamate decarboxylase 2 ( Gad2 ) do not differ between genotypes. However, we found that glutamate decarboxylase 1 ( Gad1) is significantly reduced in this PD model suggesting possible disruption of neurotransmission within the PAG. These results are the first to suggest the hypothesis that alpha-synuclein aggregation in this model is not a result of increased transcription, but rather a deficit in the breakdown and clearance, and that the observed vocal deficits may be related to impaired neural transmission. Altogether, these findings are consistent with the hypothesis that differences in neural substrate sensitivity contribute to the early pathogenesis of vocalizations and motivation to communicate in the Pink1 -/- rat model of PD. Our results suggest novel therapeutic pathways, including the lysosomal degradation pathway, which can be used in to further study the pathogenesis and treatment of vocal dysfunction PD. [ABSTRACT FROM AUTHOR]

Pathogenesis of degenerative diseases is complex and multifaceted. The disease phenotypes depend on the location of injury/damage in the brain networks and pathologically are characterized by loss of brain cells. The reason for this loss appears to be an accumulation of misfolded and dysfunctional proteins that trigger apoptotic cell death. The role of alpha-synuclein mutations, its interaction with other proteins and the cellular environment is discussed in the context of selective neuron loss. [ABSTRACT FROM AUTHOR]

• Interaction between Hb and α-syn is present in human peripheral erythrocytes. • Hb-α-syn levels in erythrocytes increased in patients with MSA. • Erythrocytic Hb-α-syn could reflect α-syn accumulation in MSA patients. Previous studies have shown that α-synuclein (α-syn) accumulation in the normal aging brain is associated with a parallel increase in hemoglobin-binding α-syn (Hb-α-syn) in the brain and peripheral erythrocytes (ERCs), indicating that Hb-α-syn levels in ERCs may reflect the α-syn changes in the brain. However, if there is any change in ERC Hb-α-syn levels in disease condition is unclear. In this study, Hb-α-syn levels in ERCs from 149 Patients with multiple system atrophy (MSA) and 149 healthy controls (HCs) were measured by enzyme linked immunosorbent assay (ELISA). The results showed that Hb-α-syn levels in ERCs were significantly increased in MSA patients in comparison with those in HCs (777.84 ± 240.82 ng/mg vs 508.84 ± 162.57 ng/mg, P < 0.001). Receiver operating characteristic curve (ROC) indicated that increased Hb-α-syn in ERCs could discriminate MSA patients from HCs, with a sensitivity of 71.8%, a specificity of 80.5%, and an area under the curve (AUC) of 0.837. The positive and negative predictive values at a cut-off value of 616.12 ng/mg were 78.7% and 74.1%, respectively. However, the increase in Hb-α-syn levels did not show any association with the age of onset and consultation, disease duration, and UMSARS (I-IV) score. This pilot study suggests that ERC Hb-α-syn is increased in MSA patients and could evaluate α-syn accumulation in the brain of patients. [ABSTRACT FROM AUTHOR]

We aimed to compare immunoreactivity patterns of four different anti-α-syn antibodies in surgical specimens of the gastrointestinal tract of Parkinson disease and control cases. Surgical specimens from stomach, small and large bowel of 6 PD cases and 12 controls were studied. Primary antibodies: anti-α-syn clone KM51, anti-phosphorylated α-syn Ser129, anti-α-syn clone 15G7 and anti-nitrated α-syn505. We found different immunoreactivity patterns: (a) coarse, Lewy-body-like aggregates labelled by the 4 antibodies and detected in 4/6 PD cases and in 1/12 controls; (b) distinct punctate cytoplasmic staining of ganglion cells labelled by anti-phosphorylated-α-syn and detected in 3/6 PD cases and 3/12 controls; (c) fine diffuse, synaptic-type staining of neural structures labelled by anti-α-syn-15G7 and anti-nitrated-α-syn505 and detected in all subjects. We conclude that different specific and non-specific immunoreactivity patterns are detected in surgical specimens of gastrointestinal tract when using different anti-α-syn antibodies, as they recognize different epitopes and states of alpha-synuclein protein. Coarse aggregates in neural structures seem to be the most promising marker for the diagnosis of Lewy-body parkinsonism when evaluating abnormal α-syn in the gastrointestinal tract. [ABSTRACT FROM AUTHOR]

Notch signaling pathway is well known that it is involved in regulating cell fate, proliferation and homeostasis. In this study, we show a novel function of alpha-synuclein (SNCA) to promote degradation of Notch1 intracellular domain (Notch1-IC) through Fbw7, ubiquitin E3 ligase. We identified that SNCA inhibits Notch1 transcription activity and diminishes the interaction between Notch1-IC and RBP-Jk. We also found decrease of Notch1-IC protein stability by exogenous and endogenous SNCA through proteasomal pathway, not through lysosomal pathway. And, we found that SNCA promotes interaction between Notch1-IC and Fbw7. Furthermore, SNCA directly interacts with Fbw7. SNCA increases ubiquitination of Notch-IC by Fbw7 through interaction with Fbw7. Together, these results suggest that SNCA is a novel regulator of Notch1-IC transcriptional activity with acting as an enhancer of the interaction of Notch1-IC and Fbw7 with increasing degradation of Notch1-IC. [ABSTRACT FROM AUTHOR]

In Parkinson’s disease (PD) alpha-synuclein oligomers are thought to be pathogenic, and 3,4-dihydroxyphenylacetaldehyde (DOPAL), an obligate aldehyde intermediate in neuronal dopamine metabolism, potently oligomerizes alpha-synuclein. PD involves alpha-synuclein deposition in brainstem raphe nuclei; however, whether 5-hydroxyindoleacetaldehyde (5-HIAL), the aldehyde of serotonin, oligomerizes alpha-synuclein has been unknown. In this study we tested whether 5-HIAL oligomerizes alpha-synuclein in vitro and in PC12 cells conditionally over-expressing alpha-synuclein. Alpha-synuclein oligomers were quantified by western blotting after incubation of alpha-synuclein with serotonin and monoamine oxidase-A (MAO-A) to generate 5-HIAL or dopamine to generate DOPAL. Oligomerization of alpha-synuclein in PC12 cells over-expressing the protein was compared between vehicle-treated cells and cells incubated with levodopa to generate DOPAL or 5-hydroxytryptophan to generate 5-HIAL. Monoamine aldehyde mediation of the oligomerization was assessed using the MAO inhibitor, pargyline. Dopamine and serotonin incubated with MAO-A both strongly oligomerized alpha-synuclein (more than 10 times control); pargyline blocked the oligomerization. In synuclein overexpressing PC12 cells, levodopa and 5-hydroxytryptophan elicited pargyline-sensitive alpha-synuclein oligomerization. 5-HIAL oligomerizes alpha-synuclein both in vitro and in synuclein-overexpressing PC12 cells, in a manner similar to DOPAL. The findings may help explain loss of serotonergic neurons in PD. [ABSTRACT FROM AUTHOR]

A link between lysosomal storage diseases (LSDs) and neurodegenerative disorders associated with accumulation of presynaptic protein alpha-synuclein has been shown. Particularly, Gaucher disease (GD) patients with a deficiency of the lysosomal enzyme glucocerebrosidase (GBA) and carriers of GBA mutations are at increased risk of Parkinson's disease (PD). It remains unclear whether this link is due to increased alpha-synuclein oligomerization. Here we show that level of oligomeric alpha-synuclein form, associated with PD development, is increased in plasma of GD patients ( n = 41, median = 22.9 pg/mL, range1.57–444.58 pg/mL; controls ( n = 40, median = 6.02 pg/mL, range 1.05–103.14 pg/mL, p < 0.0001). This difference is absent in GD patients receiving enzyme replacement therapy (ERT) for more than 5 years. Moreover, the levels of alpha-synuclein oligomers in plasma are also higher in patients with other LSDs (Niemann-Pick type C, Krabbe disease, Wolman disease) compared to the median value in controls. Therefore, we suggest that mutations in the GBA gene and at least in several other LSDs genes may be associated with an increase in oligomeric alpha-synuclein in plasma. ERT applied for recovering of GBA functions in GD treatment might decrease formation of plasma oligomeric alpha-synuclein. [ABSTRACT FROM AUTHOR]

Mutations in β-glucocerebrosidase, the genetic defect in Gaucher disease (GD), are an important susceptibility factor for Parkinson disease (PD). A PD effector is α-synuclein ( SNCA ) hypothesized to selectively interact with β-glucocerebrosidase under lysosomal conditions. SNCA polymorphism rs356219 may be associated with early-age-onset PD, common among patients with GD + PD. The objective of this study was to ascertain rs356219 genotypes of GD + PD patients. All GD + PD patients at our Gaucher referral clinic were asked to participate. A GD-only sex-, age-, GD genotype-, and enzyme therapy (ERT)-matched control was found for each GD + PD participant. Student's t -test was used ( p -value <0.05 as significant). There were 14 GD + PD patients: all Ashkenazi Jewish; 11 males (78.6%); mean (range) age diagnosed GD 34.2 (5–62) years; 50% N370S homozygous; mild to moderate GD; 3 asplenic and only these have osteonecrosis; 5 received ERT; mean age (range) diagnosed PD was 57.8 (43–70) years; first PD sign was tremor in 9 (64.3%); cognitive dysfunction in all. In GD + PD, frequency for AG + GG (9) was greater than AA (5); in GD only, there was equality (7). Odds Ratio risk for PD increases with number minor alleles: but not significantly greater among GD + PD than GD only; in aggregate, there was no difference between cohorts for frequency of minor alleles. The limitation of this study is few GD + PD, albeit virtually all the GD + PD cohort >500 adult GD patients in our clinic. Nonetheless, as a foray into potential genetic GD susceptibility for a synucleinopathy, this study suggests the need for collaboration to achieve larger sample size. [ABSTRACT FROM AUTHOR]

Highlights: [•] We established pyrosequencing assays examining DNA methylation of SNCA intron 1. [•] It is useful to study the epigenetic regulation of α-synuclein and PD biomarkers. [•] No difference in DNA methylation between PD and control leukocytes was identified. [ABSTRACT FROM AUTHOR]

Highlights: [•] Divalent metal ions augment DOPAL-induced oligomerization of alpha-synuclein. [•] Valency, not redox state, determines the augmentation of oligomerization. [•] Dopamine and deaminated metabolites besides DOPAL do not oligomerize synuclein. [•] Anti-oxidant treatment or divalent ion chelation attenuates metal ion effect. [•] Cu2+ augments DOPAL-induced dimerization of alpha-synuclein in PC12 cells. [ABSTRACT FROM AUTHOR]

Highlights: [•] We determined the association of rs356165–rs11931074 and PD-risk in a Spanish cohort. [•] We measured the RNA levels of the four SNCA isoforms in postmortem brain tissues. [•] We did not find a correlation of genotype with isoforms level. [•] We found a tendency of higher levels of the three short SNCA isoforms in the SN of PD brains. [ABSTRACT FROM AUTHOR]