Pathogenesis Of PD Research Articles

Dietary Antioxidants and Risk of Parkinson's Disease in the Singapore Chinese Health Study.

BackgroundDespite experimental evidence implicating oxidative stress in the pathogenesis of PD, epidemiological studies have provided inconsistent associations between dietary antioxidants and risk of developing PD. Furthermore, no study has been done in any Asian population.ObjectivesWe examined the associations for intake levels of dietary carotenoids (α‐carotene, β‐carotene, lycopene, β‐cryptoxanthin, and lutein) and vitamins (vitamin A, C and E) and the risk of developing PD.MethodsWe used data from the Singapore Chinese Health Study, a population‐based prospective cohort of 63,257 men and women aged 45 to 74 years during enrollment in 1993–1998. Antioxidant intake was derived from a validated semiquantitative food frequency questionnaire. Incident cases were identified through follow‐up interviews, hospital records, or PD registries through 31 July 2018. Hazard ratios and corresponding 95% confidence intervals were derived from multivariable Cox proportional hazard regression models with adjustment for other lifestyle and dietary factors.ResultsDuring an average 19.4 years of follow‐up, 544 incident PD cases were identified. No association was found for dietary carotenoids, individually or summed. Hazard ratio comparing highest to lowest quartile for total carotenoids was 0.98 (95% confidence interval: 0.76–1.28; P trend = 0.83). There were also no clear dose‐dependent associations of dietary vitamins A, C, and E with risk of developing PD (all P trend ≥ 0.10). Sensitive analyses with lag time and excluding supplement use did not materially alter results.ConclusionsIntake of dietary antioxidants, such as carotenoids and vitamins, was not associated with the risk of developing PD in Singaporean Chinese. © 2020 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Characterization of a pathogenic variant in GBA for Parkinson\u2019s disease with mild cognitive impairment patients

Parkinson’s disease (PD) is the second most common neurodegenerative disease, and mild cognitive impairment (MCI) is a well-established risk factor for the development of dementia in PD. A growing body of evidence suggests that low expression of glucocerebrosidase (GBA) promotes the transmission of α-synuclein (α-Syn) interpolymers and the progression of PD. However, how GBA mutations affect the pathogenesis of PD via abnormal aggregation of α-Syn is unclear, and no clinically valid PD-MCI genetic markers have been identified. Here, we first located a GBA eQTL, rs12411216, by analysing DHS, eQTL SNP, and transcription factor binding site data using the UCSC database. Subsequently, we found that rs12411216 was significantly associated with PD-MCI (P < 0.05) in 306 PD patients by genotyping. In exploring the relationship between rs12411216 and GBA expression, the SNP was found to be associated with GBA expression in 50 PD patients through qPCR verification. In a further CRISPR/Cas9-mediated genome editing module, the SNP was identified to cause a decrease in GBA expression, weaken enzymatic activity and enhance the abnormal aggregation of α-Syn in SH-SY5Y cells. Additionally, using an electrophoretic mobility shift assay, we confirmed that the binding efficiency of transcription factor E2F4 was affected by the rs12411216 SNP. In conclusion, our results showed that rs12411216 regulated GBA expression, supporting its potential role as a PD-MCI genetic biomarker and highlighting novel mechanisms underlying Parkinson’s disease.

NLRP3 inflammasome inhibitor MCC950 attenuates primary dysmenorrhea in mice via the NF-\u03baB/COX-2/PG pathway

BackgroundPrimary dysmenorrhea (PD) constitutes a common gynecological disease among young women. The NLRP3 inflammasome may be activated and expressed in PD, but the mechanistic link between NLRP3 inflammasome activation and PD is still unclear.MethodsTo investigate the potential role of NLRP3 inflammasome activation in the pathogenesis of PD, 30 female Kunming mice without pregnancy were used for experiments. The PD mouse model was constructed by 11 days of successive co-treatment with estradiol and oxytocin. MCC950, a potent and specific small-molecule inhibitor of the NLRP3 inflammasome, was used to treat PD mice. The disease level was assessed by the writhing response and hot water tail-flick test. The levels of prostaglandin E2 (PGE2) and prostaglandin F2 alpha (PGF2α) in the uterine tissues of mice were detected by ELISA. The expression levels of protein and cytokines, including NLRP3, cysteine aspartic acid-specific protease 1 (caspase-1), interleukin (IL)-1β, IL-18, nuclear factor kappa B (NF-κB) p65, phospho-NF-κB p65, and cyclooxygenase-2 (COX-2) were revealed by western blot analysis.ResultsMCC950 greatly ameliorated the writhing response induced by the combination of oxytocin and estradiol, with an increasing length of tail-flick latency. MCC950 also significantly decreased the levels of PGF2α and PGE2, and the expressions of NLRP3, caspase-1, IL-1β, IL-18, phospho-NF-κB p65, NF-κB p65, and COX-2 in the uterus.ConclusionsMCC950 markedly alleviated the pain and pathological damage in PD mice by inhibiting NLRP3 activation. The underlying mechanism may be related to hypoactive uterine inflammation via suppression of NLRP3 activation and the NF-κB/COX-2/PG pathway in uteruses of PD mice.

Human telomerase reverse transcriptase positively regulates mitophagy by inhibiting the processing and cytoplasmic release of mitochondrial PINK1

Mutations in the phosphatase and tensin homologue-induced putative kinase 1 (PINK1) gene have been linked to an early-onset autosomal recessive form of familial Parkinson′s disease (PD). PINK1, a mitochondrial serine/threonine-protein kinase, plays an important role in clearing defective mitochondria by mitophagy – the selective removal of mitochondria through autophagy. Evidence suggests that alteration of the PINK1 pathway contributes to the pathogenesis of PD, but the mechanisms by which the PINK1 pathway regulates mitochondrial quality control through mitophagy remain unclear. Human telomerase reverse transcriptase (hTERT) is a catalytic subunit of telomerase that functions in telomere maintenance as well as several non-telomeric activities. For example, hTERT has been associated with cellular immortalization, cell growth control, and mitochondrial regulation. We determined that hTERT negatively regulates the cleavage and cytosolic processing of PINK1 and enhances its mitochondrial localization by inhibiting mitochondrial processing peptidase β (MPPβ). Consequently, hTERT promotes mitophagy following carbonyl cyanide m-chlorophenylhydrazone (CCCP)-induced mitochondrial dysfunction and improves the function of damaged mitochondria by modulating PINK1. These findings suggest that hTERT positively regulates PINK1 function, leading to increased mitophagy following mitochondrial damage.

Characterization of Age-dependent Behavior Deficits in the PGC-1α Knockout Mouse, in Relevance to the Parkinson's Disease Model

Parkinson’s disease is a disorder of adult onset involving the progressive degeneration of selective portions of the central nervous system. It is known that mitochondrial dysfunction is involved in the pathogenesis of PD. Given that PGC-1α induces proliferation of mitochondria via transcription regulation, it is possible that PGC-1α pathway dysregulation is involved in PD pathogenesis. To determine how derangement of the PGC-1α pathway in age contributes to PD, in this study, we have characterized the number of dopaminergic neuron in the substantia nigra pars compacta (SNpc), motor behaviors and related expression of mitochondrial markers (CoxIV, SDHA, and Tomm20) in the ventral midbrains of PGC-1α null mice. We found an overall decrease in spontaneous, voluntary movements and severely impaired motor coordination in all age groups (10 months and 20 months) of PGC-1α null mice, while pole testing detected impaired motor activity in older PGC-1α null mice only. TH-positive neurons were significantly less in older PGC-1α null mice. Concentration of DA as well as its two metabolites reduced in an age-dependent manner in PGC-1α null mice. Expression of CoxIV, SDHA and Tomm20 also significantly decreased in the ventral midbrains of 10-month-old PGC-1α null mice. Thus, PGC-1α KO in mice induced dopaminergic neuron degeneration in the SNpc and DA deficits in the striatum in an age-dependent manner. Progressive impairment of motor coordination in an age-dependent manner was correlated to the extent of nigrostriatal dopaminergic pathway degeneration and mitochondrial dysfunction.

Mutation screening and burden analysis of VPS13C in Chinese patients with early-onset Parkinson's disease

Homozygous and compound heterozygous mutations in the vacuolar protein sorting 13C (VPS13C) gene can cause autosomal recessive parkinsonism via mitochondrial pathway. The present study aimed to screen the mutations of VPS13C in a cohort of Chinese patients with early-onset Parkinson's disease (EOPD) and further explore its pathogenicity via burden analysis. A total of 669 patients with EOPD were sequenced with whole-exome sequencing and analyzed homozygous or compound heterozygous mutations in VPS13C. Moreover, rare variants with minor allele frequency <0.1% were included in the burden analysis. In total, 7 (1.05%) patients with EOPD carried compound heterozygous mutations in VPS13C, including 3 patients with novel compound heterozygous missense mutations and 4 patients with at least 1 nonsense or splicing-site mutations. Furthermore, burden analysis indicated that patients with EOPD had an enrichment of rare variants in VPS13C. In conclusion, our findings of compound missense mutations expanded the mutation spectrum of VPS13C in EOPD. Burden analysis further elucidated the importance of VPS13C in the pathogenesis of PD.

Эпигенетическая регуляция экспрессии гена SNCA при болезни Паркинсона

В настоящем исследовании проведена оценка уровня мРНК и белка генов SNCA, DNMT1, а также степени метилирования интрона 1 гена SNCA в CD45+ клетках периферической крови пациентов со спорадической болезнью Паркинсона (БП) и индивидуумов контрольной группы. Впервые было выявлено снижение концентрации белка DNMT1 в CD45+ клетках периферической крови пациентов с БП по сравнению с группой контроля. Обнаружено увеличение уровня мРНК гена DNMT1 у пациентов с БП по сравнению с контролем. Не выявлено статистически значимых различий при сравнении степени метилирования интрона 1 гена SNCA в CD45+ клетках периферической крови пациентов с БП и контроля. В группе контроля выявлена обратная корреляция степени метилирования отдельных CpG островков с концентрацией белка альфа-синуклеина и уровнем мРНК гена SNCA. Проведенное исследование позволяет предположить участие гена DNMT1 в патогенезе БП и отсутствие ассоциации степени метилирования интрона 1 гена SNCA с БП. The aim of this study was to assess the level of mRNA and protein of the SNCA, DNMT1 genes, as well as intron 1 methylation of the SNCA gene in CD45 + peripheral blood cells of patients with sporadic PD and control individuals. For the first time, a decrease in the concentration of DNMT1 protein in CD45 + peripheral blood cells from PD patients compare to controls was revealed. An increase in DNMT1 gene expression in PD patients compare to controls was found. No differences in intron 1 methylation of the SNCA gene in CD45 + peripheral blood cells was found between PD patients and controls. An inverse correlations between methylation level of 21, 22 CpG island in intron1 of SNCA gene and mRNA SNCA gene and alpha-synuclein protein level were found. The study suggests the involvement of DNMT1 in the pathogenesis of PD and the lack of association of PD with intron 1 methylation of the SNCA gene.

Анализ уровня экспрессии генов гистаминергической системы на ранней симптомной стадии болезни Паркинсона

Целью данной работы было изучение изменений экспрессии генов гистаминергической системы в развитии патологических процессов при болезни Паркинсона (БП) на ранней симптомной стадии. На МФТП-индуцированной модели ранней симптомной стадии БП (мыши-самцы линии C57BL/6 по 10 шт. в контрольной и опытной группах) проанализирована экспрессия 9 генов, имеющих отношение к гистаминергической системе, методом обратной транскрипции и ПЦР в реальном времени (TaqMan). В результате были выявлены изменения на уровне мРНК для ряда генов в тканях мозга мышей, которые могут указывать на вовлеченность гистаминергической системы в патогенез БП на ранней стадии. The goal of this work was to study changes of histaminergic system genes expression level in the early symptom stage of PD. We were use MPTP mouse model of early symptom stage of PD in this study. Male mice C57BL/6 were used (n=10 in the control and experimental groups). For analysis we were choose nine genes, which associated with histaminergic system. Measuring of expression levels was carried out using reverse transcription reaction and real-time PCR (TaqMan). Changes at the mRNA level for a number of genes in the brain tissues of mice with MPTP-induced PD were founded. Based on these data, it can be suggested that histaminergic system is involve in early stage PD pathogenesis.

Транскриптомный анализ дермальных фибробластов, полученных от близнецов, дискордантных по болезни Паркинсона

Впервые проведен анализ транскриптома фибробластов, полученных от близнецов, дискордантных по спорадической форме БП. Полученные данные свидетельствуют о потенциале исследования фибробластов больных БП для понимания процессов, участвующих в патогенезе БП, а также обращают внимание на три потенциально значимых гена-кандидата БП - GRIK2, PTGS2 и SCN9A. Analysis of transcriptome of fibroblasts, derived from twins, discordant in sporadic form of PD, have been conducted for the first time. We have obtained the evidence for potential utility of fibroblast studies for undrestanding the processes, underlying the PD pathogenesis. Also, our data highlights 3 possible candidate PD genes - GRIK2, PTGS2 &amp; SCN9A.

DJ-1 is indispensable for the S-nitrosylation of Parkin, which maintains function of mitochondria

The DJ-1 gene, a causative gene for familial Parkinson’s disease (PD), has been reported to have various functions, including transcriptional regulation, antioxidant response, and chaperone and protease functions; however, the molecular mechanism associated with the pathogenesis of PD remains elusive. To further explore the molecular function of DJ-1 in the pathogenesis of PD, we compared protein expression profiles in brain tissues from wild-type and DJ-1-deficient mice. Two-dimensional difference gel electrophoresis analysis and subsequent analysis using data mining methods revealed alterations in the expression of molecules associated with energy production. We demonstrated that DJ-1 deletion inhibited S-nitrosylation of endogenous Parkin as well as overexpressed Parkin in neuroblastoma cells and mouse brain tissues. Thus, we used genome editing to generate neuroblastoma cells with DJ-1 deletion or S-nitrosylated cysteine mutation in Parkin and demonstrated that these cells exhibited similar phenotypes characterized by enhancement of cell death under mitochondrial depolarization and dysfunction of mitochondria. Our data indicate that DJ-1 is required for the S-nitrosylation of Parkin, which positively affects mitochondrial function, and suggest that the denitrosylation of Parkin via DJ-1 inactivation might contribute to PD pathogenesis and act as a therapeutic target.

Contra-Directional Expression of Plasma Superoxide Dismutase with Lipoprotein Cholesterol and High-Sensitivity C-reactive Protein as Important Markers of Parkinson's Disease Severity.

Aim: Oxidative stress and inflammation play critical roles in the neuropathogenesis of PD. We aimed to evaluate oxidative stress and inflammation status by measuring serum superoxide dismutase (SOD) with lipoprotein cholesterol and high-sensitivity C-reactive protein (hsCRP) respectively in PD patients, and explore their correlation with the disease severity.Methods: We performed a cross-sectional study that included 204 PD patients and 204 age-matched healthy controls (HCs). Plasma levels of SOD, hsCRP, total cholesterol, high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) were measured. A series of neuropsychological assessments were performed to rate the severity of PD.Results: The plasma levels of SOD (135.7 ± 20.14 vs. 147.2 ± 24.34, P < 0.0001), total cholesterol, HDL-C and LDL-C in PD were significantly lower than those in HCs; the hsCRP level was remarkably increased in PD compared to HC (2.766 ± 3.242 vs. 1.637 ± 1.597, P < 0.0001). The plasma SOD was negatively correlated with the hsCRP, while positively correlated with total cholesterol, HDL-C, and LDL-C in PD patients. The plasma SOD were negatively correlated with H&Y, total UPDRS, UPDRS (I), UPDRS (II), and UPDRS (III) scores, but positively correlated with MoCA and MMSE scores. Besides, hsCRP was negatively correlated with MoCA; while total cholesterol, HDL-C and LDL-C were positively correlated with the MoCA, respectively.Conclusion: Our findings suggest that lower SOD along with cholesterol, HDL-C and LDL-C, and higher hsCRP levels might be important markers to assess the PD severity. A better understanding of SOD and hsCRP may yield insights into the pathogenesis of PD.

Salivary alpha-synuclein (total and oligomeric form): potential biomarkers in Parkinson\u2019s disease

BackgroundParkinson’s disease (PD) is one of the most common degenerative diseases of the central nervous system (CNS). Alpha-synuclein (A-syn) plays a critical role in the pathogenesis of PD. The close relation between the salivary glands and the CNS could render the A-syn secretions in the saliva useful biomarkers for PD.Aim of the workTo study the salivary A-syn levels in a cohort of PD Egyptian patients and to correlate these A-syn levels with the patients’ clinical data and disease severity.Patients and methodsTwenty-five PD patients and 15 age- and sex-matched healthy subjects, as a control group, were enrolled. Evaluation of PD patients was performed using the Unified Parkinson’s Disease Rating Scale (UPDRS) and modified Hoehn and Yahr scale (HYS). Samples of the saliva were analyzed using the enzyme-linked immunosorbent assay (ELISA) technique for the specific anti A-syn total and anti A-syn oligomer (A-synolig).ResultsThere was a statistically significant increase in A-synolig level and A-synolig/A-syn total ratio and a decrease in A-syn total level among PD patients. A statistically significant increase in A-synolig level was detected among patients having bradykinesia and rigidity as predominant symptoms. Also, there was a statistically significant positive correlation between A-synolig level and the disease duration. No statistically significant correlation was found between A-syn concentrations and disease severity.ConclusionSalivary A-syn total and A-synolig can be used as potential biomarkers for PD diagnosis.

Alteration of brain temperature and systemic inflammation in Parkinson\u2019s disease

ObjectivesParkinson’s disease (PD) is known to be related to various factors, including neuroinflammation, increased oxidative stress, and brain temperature alteration. We aimed to evaluate the correlation between these factors using diffusion-weighted imaging (DWI) thermometry and blood tests of systemic inflammation.MethodsFrom July 2012 to Jun 2017, 103 patients with PD (44 men and 59 women; mean age, 60.43 ± 9.12 years) and 106 sex- and age-matched healthy volunteers (48 men and 58 women; mean age, 58.16 ± 8.45 years) retrospectively underwent magnetic resonance DWI thermometry to estimate brain intraventricular temperature (Tv). Subjects were divided into three subgroups in light of their ages. The tested inflammatory markers included plasma nuclear DNA, mitochondrial DNA, apoptotic leukocytes, and serum adhesion molecules. The correlations among the Tv values, clinical severity, and systemic inflammatory markers were then calculated.ResultsThe PD patients did not show a natural trend of decline in Tv with age. Comparisons among the different age groups revealed that the younger PD subjects had significantly lower Tv values than the younger controls, but the older subjects had no significant group differences. Overall, the PD patients exhibited lower Tv values than the controls, as well as increased oxidative stress. The brain temperature showed positive correlations with inflammatory markers, including plasma nuclear DNA and L-selectin levels, in all the subjects.ConclusionsPossible pathophysiological correlations between systemic inflammation and brain temperature were indicated by the results of this study, a finding which may aid us in investigating the underlying pathogenesis of PD.

A Novel Antisense &lt;i&gt;Alu&lt;/i&gt; Insertion/Deletion Polymorphism of &lt;i&gt;ALDH1A1&lt;/i&gt; Modulates Risk of Parkinson's Disease

Background: Studies in animal models have suggested that aldehyde dehydrogenase 1 (encoded by ALDH1A1) protects against PD by reducing toxic metabolite of dopamine. Herein we aimed to investigate whether ALDH1A1 is genetically associated with PD susceptibility in humans. Methods: A Han Chinese population comprised of 506 sporadic PD patients and 533 controls was recruited to analyze six tag-single nucleotide polymorphisms (SNPs) of ALDH1A1, followed by haplotype analyses and further functional analyses of an associated insertion/deletion polymorphism. Findings: The tag-SNP rs7043217 was significantly associated with PD susceptibility with the T serving as a risk allele (P = 0.006, OR = 1.278, 95% CI =1.074-1.520). Multiple haplotypes led to abnormalities of PD risk, topped by a 4-SNP GGTA module in order of rs4646547, rs1888202, rs7043217 and rs647880 (P = 9.610 × 10-8, OR = 6.420, 95% CI = 2.944-13.998). An insertion/deletion polymorphism of a novel antisense Alu element, herein named Yb8c4, was identified in intron 4 of ALDH1A1, which was in complete linkage disequilibrium with rs7043217. The antisense Yb8c4 insertion displayed a suppressive activity on gene transcription. Interpretation: ALDH1A1 variation, as featured by the antisense Yb8c4 insertion/deletion polymorphism, modulates PD risk in human populations. Our results provide novel genetic insights into the role of ALDH1 in PD pathogenesis. Funding Statement: The study was supported in part by funding from National Natural Science Foundation of China (31701080, 81571087, 81771380 and 81771510), Zhejiang Provincial Natural Science Foundation (LD19H090001 and LZ19H090002), Science and Technology Department of Zhejiang Province (2018C37111), and Wenzhou Municipal Science and Technology Bureau (C20170003). Declaration of Interests: The authors declare no conflict of interest. Ethics Approval Statement: The study was approved by the ethics committee of the Second Affiliated Hospital and Yuying Children’s hospital, Wenzhou Medical University.

Organochlorine pesticide levels in Greek patients with Parkinson’s disease

BackgroundParkinson’s disease (PD) is a neurodegenerative disease, mostly presenting with characteristic motor symptoms. Organochlorines (OC) are a class of widely-used pesticides that have been included among the list of environmental factors incriminated in PD pathogenesis. However, most studies reporting this association are based on questionnaires, and few have reported exposure data. AimTo examine the relationship between OC blood concentrations and PD risk. MethodsIn the present study, we studied the concentrations of 8 OC compounds (hexachlorobenzene, heptachlor, hepachlor epoxide, c-chlordane, a-chlordane, p,p’-DDE, DDD, DDT) in 104 Greek PD patients and 110 healthy controls. ResultsAll substances studied were present in at least one sample. The most frequently detected (above the level of quantification) pesticides were p,p’-DDE (n = 214, 100 % of both groups) and hexachlorobenzene, HCB (n = 189, cases 46.5 %, controls 53.5 %). Higher levels of DDE were detected among PD patients in comparison to controls by using logistic regression analysis to control for confounders [Odds Ratio, OR (95 % confidence interval, C.I.)]: 2.592,(1.29–5.21)], whilst lower levels of HCB were detect among PD patients [OR,95 %CI:0.176(0.09−0.35)]. ConclusionsOur data suggest that exposure to specific OCs is related to the risk of PD. Further studies, using real exposure data, are needed in order to confirm and extend these findings.

Serum growth differentiation factor 15, but not lactate, is elevated in patients with Parkinson's disease

BackgroundParkinson's disease (PD) is among the most frequently-occurring neurodegenerative diseases in humans. Although mitochondrial dysfunction is suggested to play a central role in PD pathogenesis, few studies have clinically evaluated mitochondrial function in PD patients. We therefore aimed to determine whether mitochondrial function is altered in PD patients by applying two approaches that are normally used for the diagnosis of mitochondrial disorder (MD). MethodsWe measured serum growth differentiation factor 15 (GDF15) levels in 36 PD patients, 30 age-matched healthy controls, and 5 MD patients. Among these, 20 PD patients and 18 healthy controls underwent the lactate stress test. Serum GDF15 levels were evaluated with respect to clinical characteristics. ResultsMean GDF15 levels were significantly higher in the PD (1472 pg/mL, p = .034) and MD (3363 pg/mL, p < .001) groups than in the control group (1093 pg/mL). The lactate stress test exhibited no significant differences between PD patients and controls. Age was identified as an independent factor that correlated with serum GDF15 levels in both groups. In PD patients, there was no significant difference between serum GDF15 levels and other clinical parameters including sex, cognitive function, and lifestyle. ConclusionSerum GDF15 levels, but not lactate levels, were elevated in Japanese patients with PD, thus highlighting the potential association between PD and GDF15.

Finnish Parkinson\u2019s disease study integrating protein-protein interaction network data with exome sequencing analysis

Variants associated with Parkinson’s disease (PD) have generally a small effect size and, therefore, large sample sizes or targeted analyses are required to detect significant associations in a whole exome sequencing (WES) study. Here, we used protein-protein interaction (PPI) information on 36 genes with established or suggested associations with PD to target the analysis of the WES data. We performed an association analysis on WES data from 439 Finnish PD subjects and 855 controls, and included a Finnish population cohort as the replication dataset with 60 PD subjects and 8214 controls. Single variant association (SVA) test in the discovery dataset yielded 11 candidate variants in seven genes, but the associations were not significant in the replication cohort after correction for multiple testing. Polygenic risk score using variants rs2230288 and rs2291312, however, was associated to PD with odds ratio of 2.7 (95% confidence interval 1.4–5.2; p < 2.56e-03). Furthermore, an analysis of the PPI network revealed enriched clusters of biological processes among established and candidate genes, and these functional networks were visualized in the study. We identified novel candidate variants for PD using a gene prioritization based on PPI information, and described why these variants may be involved in the pathogenesis of PD.

PINK1 phosphorylates ubiquitin predominantly in astrocytes

Loss-of-function mutations in PINK1 are causally linked to recessively inherited Parkinson’s disease (PD), with marked loss of dopaminergic neurons in the substantia nigra that are required for normal movement. PINK1 is a nuclear-encoded mitochondrial-targeted kinase that phosphorylates a conserved serine at amino acid 65 (pS65) in ubiquitin as well as Parkin, another gene with loss-of-function mutations linked to recessive parkinsonism. The steady-state levels of PINK1 protein are very low, even in cells that express PINK1, because PINK1 is normally targeted for degradation after mitochondrial import by a process that is dependent upon mitochondrial membrane potential. Dissipation of the mitochondrial membrane potential with ionophores, such as CCCP and valinomycin, causes the accumulation of PINK1 on the outer mitochondrial membrane, a marked increase of pS65-ubiquitin and the recruitment of Parkin, which targets dysfunctional mitochondria for degradation by autophagy. While the high penetrance of PINK1 mutations establish its critical function for maintaining neurons, the activity of PINK1 in primary neurons has been difficult to detect. Mounting evidence implicates non-neuronal cells, including astrocytes and microglia, in the pathogenesis of both idiopathic and inherited PD. Herein we used both western analysis and immunofluorescence of pS65-ubiquitin to directly compare the activity of PINK1 in primary neurons, astrocytes, microglia, and oligodendrocyte progenitor cells cultured from the brains of wild-type (WT) and PINK1 knockout (KO) rat pups. Our findings that PINK1-dependent ubiquitin phosphorylation is predominantly in astrocytes supports increased priority for research on the function of PINK1 in astrocytes and the contribution of astrocyte dysfunction to PD pathogenesis.

Cellular alterations identified in pluripotent stem cell-derived midbrain spheroids generated from a female patient with progressive external ophthalmoplegia and parkinsonism who carries a novel variation (p.Q811R) in the POLG1 gene

Variations in the POLG1 gene encoding the catalytic subunit of the mitochondrial DNA polymerase gamma, have recently been associated with Parkinson’s disease (PD), especially in patients diagnosed with progressive external ophthalmoplegia (PEO). However, the majority of the studies reporting this association mainly focused on the genetic identification of the variation in POLG1 in PD patient primary cells, and determination of mitochondrial DNA copy number, providing little information about the cellular alterations existing in patient brain cells, in particular dopaminergic neurons. Therefore, through the use of induced pluripotent stem cells (iPSCs), we assessed cellular alterations in novel p.Q811R POLG1 (POLG1Q811R) variant midbrain dopaminergic neuron-containing spheroids (MDNS) from a female patient who developed early-onset PD, and compared them to cultures derived from a healthy control of the same gender. Both POLG1 variant and control MDNS contained functional midbrain regionalized TH/FOXA2-positive dopaminergic neurons, capable of releasing dopamine. Western blot analysis identified the presence of high molecular weight oligomeric alpha-synuclein in POLG1Q811R MDNS compared to control cultures. In order to assess POLG1Q811R-related cellular alterations within the MDNS, we applied mass-spectrometry based quantitative proteomic analysis. In total, 6749 proteins were identified, with 61 significantly differentially expressed between POLG1Q811R and control samples. Pro- and anti-inflammatory signaling and pathways involved in energy metabolism were altered. Notably, increased glycolysis in POLG1Q811R MDNS was suggested by the increase in PFKM and LDHA levels and confirmed using functional analysis of glycolytic rate and oxygen consumption levels. Our results validate the use of iPSCs to assess cellular alterations in relation to PD pathogenesis, in a unique PD patient carrying a novel p.Q811R variation in POLG1, and identify several altered pathways that may be relevant to PD pathogenesis.

NG2 glia regulate brain innate immunity via TGF-\u03b22/TGFBR2 axis

BackgroundBrain innate immunity is vital for maintaining normal brain functions. Immune homeostatic imbalances play pivotal roles in the pathogenesis of neurological diseases including Parkinson’s disease (PD). However, the molecular and cellular mechanisms underlying the regulation of brain innate immunity and their significance in PD pathogenesis are still largely unknown.MethodsCre-inducible diphtheria toxin receptor (iDTR) and diphtheria toxin-mediated cell ablation was performed to investigate the impact of neuron-glial antigen 2 (NG2) glia on the brain innate immunity. RNA sequencing analysis was carried out to identify differentially expressed genes in mouse brain with ablated NG2 glia and lipopolysaccharide (LPS) challenge. Neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated mice were used to evaluate neuroinflammatory response in the presence or absence of NG2 glia. The survival of dopaminergic neurons or glial cell activation was evaluated by immunohistochemistry. Co-cultures of NG2 glia and microglia were used to examine the influence of NG2 glia to microglial activation.ResultsWe show that NG2 glia are required for the maintenance of immune homeostasis in the brain via transforming growth factor-β2 (TGF-β2)-TGF-β type II receptor (TGFBR2)-CX3C chemokine receptor 1 (CX3CR1) signaling, which suppresses the activation of microglia. We demonstrate that mice with ablated NG2 glia display a profound downregulation of the expression of microglia-specific signature genes and remarkable inflammatory response in the brain following exposure to endotoxin lipopolysaccharides. Gain- or loss-of-function studies show that NG2 glia-derived TGF-β2 and its receptor TGFBR2 in microglia are key regulators of the CX3CR1-modulated immune response. Furthermore, deficiency of NG2 glia contributes to neuroinflammation and nigral dopaminergic neuron loss in MPTP-induced mouse PD model.ConclusionsThese findings suggest that NG2 glia play a critical role in modulation of neuroinflammation and provide a compelling rationale for the development of new therapeutics for neurological disorders.