GBA-associated Parkinson's Disease Research Articles

IPSC-Derived Astrocytes Contribute to In Vitro Modeling of Parkinson's Disease Caused by the GBA1 N370S Mutation.

Parkinson's disease (PD) is a neurodegenerative disorder that ranks second in prevalence after Alzheimer's disease. The number of PD diagnoses increases annually. Nevertheless, modern PD treatments merely mitigate symptoms rather than preventing neurodegeneration progression. The creation of an appropriate model to thoroughly study the mechanisms of PD pathogenesis remains a current challenge in biomedicine. Recently, there has been an increase in data regarding the involvement of not only dopaminergic neurons of the substantia nigra but also astrocytes in the pathogenesis of PD. Cell models based on induced pluripotent stem cells (iPSCs) and their differentiated derivatives are a useful tool for studying the contribution and interaction of these two cell types in PD. Here, we generated two iPSC lines, ICGi034-B and ICGi034-C, by reprogramming peripheral blood mononuclear cells of a patient with a heterozygous mutation c.1226A>G (p.N370S) in the GBA1 gene by non-integrating episomal vectors encoding OCT4, KLF4, L-MYC, SOX2, LIN28, and mp53DD. The iPSC lines demonstrate the expression of pluripotency markers and are capable of differentiating into three germ layers. We differentiated the ICGi034-B and ICGi034-C iPSC lines into astrocytes. This resulting cell model can be used to study the involvement of astrocytes in the pathogenesis of GBA-associated PD.

Chapter 10 - Genetic mechanism vs genetic subtypes: The example of GBA

Genetic variants in GBA, encoding the lysosomal enzyme glucocerebrosidase (GCase), are common risk factors for Parkinson's disease (PD). Genotype-phenotype studies have demonstrated that different types of GBA variants have differential effects on the phenotype. Variants could be classified as mild or severe depending on the type of Gaucher disease they cause in the biallelic state. It was shown that severe GBA variants, as compared to mild variants, are associated with higher risk of PD, earlier age at onset, and faster progression of motor and nonmotor symptoms. The observed difference in phenotype might be caused by a diversity of cellular mechanisms related to the particular variants. The lysosomal function of GCase is thought to play a significant role in the development of GBA-associated PD, and other mechanisms such as endoplasmic reticulum retention, mitochondrial dysfunction, and neuroinflammation have also been suggested. Moreover, genetic modifiers such as LRRK2, TMEM175, SNCA, and CTSB can either affect GCase activity or modulate risk and age at onset of GBA-associated PD. To achieve ideal outcomes with precision medicine, therapies will have to be tailored to individuals with specific variants, potentially in combination with known modifiers.

Дисфункция глюкоцереброзидазы и накопление альфа-синуклеина - патофизиологический дуэт при GBA-ассоциированной болезни Паркинсона

Глюкоцереброзидаза (GCase) - лизосомный фермент, кодируемый геном GBA. Мутации в гене GBA являются наиболее распространенным генетическим фактором риска болезни Паркинсона (БП). Гомозиготное носительство мутаций в гене GBA приводит к развитию болезни Гоше (БГ). Было показано, что мутации в гене GBA могут влиять на накопление белка альфа-синуклеина, агрегация которого рассматривается в настоящее время как ключевое звено патогенеза БП. В данном исследовании нами была сопоставлена ферментативная активность GCase, концентрация субстрата фермента HexSph и уровень белка альфа-синуклеина в первичной культуре макрофагов периферической крови пациентов с БГ, GBA-ассоциированной БП, бессимптомных носителей мутации в гене GBA (GBA-носителей), а также в присутствии селективного ингибитора GCase кондуритол-В-эпоксида (CBE) как на первичной культуре макрофагов контрольной группы пациентов, так и в клетках мозга модельных животных (мышей). В результате проведенного исследования на первичной культуре макрофагов, а также в клетках мозга мышиной модели показано, что при снижении активности GCase происходит накопление субстрата HexSph. На модельных животных нами впервые показано влияние ингибирования функции GCase на накопление олигомерных форм альфа-синуклеина. В макрофагах носителей мутаций в гене GBA было показано понижение активности GCase и накопление субстрата вне зависимости от наличия патологии. Таким образом, исходя из полученных данных можно предположить, что выраженная дисфункция GCase сопровождается накоплением лизосфинголипидов и изменением катаболизма альфа-синуклеина как в клетках первичной культуры макрофагов человека, так в клетках модельных животных. Glucocerebrosidase (GCase) is a lysosomal enzyme encoded by the GBA gene, mutations in which are the most common genetic risk factor for Parkinson’s disease (PD). Homozygous carriage of mutations in the GBA gene leads to the development of Gaucher disease (GD). It has been shown that mutations in the GBA gene can affect the accumulation of alpha-synuclein protein. Its aggregation is currently considered as a key link in the pathogenesis of PD. In this study, we compared the enzymatic activity of GCase, the concentration of the HexSph enzyme substrate and the level of alpha-synuclein protein in the primary culture of macrophages of patients with GD, GBA-associated PD, asymptomatic carriers of mutation in the GBA gene and control group individuals in the presence of a selective GCase inhibitor conduritol-B-epoxide, as well as in the brain cells of model animals with lysosome dysfunction. As a result of the study conducted on the primary culture of macrophages, as well as on animal models, it was shown that lysosome dysfunction leads to decreased GCase activity and HexSph accumulation. In this study on model animals, we have shown for the first time the effect of GCase function inhibition on the oligomeric forms of alpha-synuclein accumulation.

SWATH Mass Spectrometry-Based CSF Proteome Profile of GBA-Linked Parkinson's Disease Patients.

β-glucocerebrosidase (GBA)-associated mutations are a significant risk factor for Parkinson's disease (PD) that aggravate the disease pathology by upregulating the deposition of α-Synuclein (α-Syn). The resultant clinical profile varies for PD patients without GBA mutations. The current study aimed to identify the proteomic targets involved in the pathogenic pathways leading to the differential clinical presentation of GBA-associated PD. CSF samples (n = 32) were obtained from PD patients with GBA mutations (n = 22), PD patients without GBA mutations (n = 7), and healthy controls that were carriers of GBA mutations (n = 3). All samples were subjected to in-gel tryptic digestion followed by the construction of the spectral library and quantitative SWATH-based analysis. CSF α-Syn levels were reduced in both PDIdiopathic and PDGBA cases. Our SWATH-based mass spectrometric analysis detected 363 proteins involved in immune response, stress response, and cell signaling in various groups. Intergroup analysis showed that 52 proteins were significantly up- or downregulated in various groups. Of these 52 targets, 20 proteins were significantly altered in PDGBA cases only while 2 showed different levels in PDIdiopathic patients. Our results show that the levels of several pathologically relevant proteins, including Contactin-1, Selenium-binding protein 1, Adhesion G Protein-Coupled Receptor, and Apolipoprotein E are significantly different among the sporadic and genetic variants of PD and hint at aggravated synaptic damage, oxidative stress, neuronal loss, and aggregation of α-Syn in PDGBA cases.

GBA Variants and Parkinson Disease: Mechanisms and Treatments.

The GBA gene encodes for the lysosomal enzyme glucocerebrosidase (GCase), which maintains glycosphingolipid homeostasis. Approximately 5–15% of PD patients have mutations in the GBA gene, making it numerically the most important genetic risk factor for Parkinson disease (PD). Clinically, GBA-associated PD is identical to sporadic PD, aside from the earlier age at onset (AAO), more frequent cognitive impairment and more rapid progression. Mutations in GBA can be associated with loss- and gain-of-function mechanisms. A key hallmark of PD is the presence of intraneuronal proteinaceous inclusions named Lewy bodies, which are made up primarily of alpha-synuclein. Mutations in the GBA gene may lead to loss of GCase activity and lysosomal dysfunction, which may impair alpha-synuclein metabolism. Models of GCase deficiency demonstrate dysfunction of the autophagic-lysosomal pathway and subsequent accumulation of alpha-synuclein. This dysfunction can also lead to aberrant lipid metabolism, including the accumulation of glycosphingolipids, glucosylceramide and glucosylsphingosine. Certain mutations cause GCase to be misfolded and retained in the endoplasmic reticulum (ER), activating stress responses including the unfolded protein response (UPR), which may contribute to neurodegeneration. In addition to these mechanisms, a GCase deficiency has also been associated with mitochondrial dysfunction and neuroinflammation, which have been implicated in the pathogenesis of PD. This review discusses the pathways associated with GBA-PD and highlights potential treatments which may act to target GCase and prevent neurodegeneration.

Role of Lysosomal Gene Variants in Modulating GBA-Associated Parkinson's Disease Risk.

BackgroundTo date, variants in the GBA gene represent the most frequent large‐effect genetic factor associated with Parkinson's disease (PD). However, the reason why individuals with the same GBA variant may or may not develop neurodegeneration and PD is still unclear.ObjectivesTherefore, we evaluated the contribution of rare variants in genes responsible for lysosomal storage disorders (LSDs) to GBA‐PD risk, comparing the burden of deleterious variants in LSD genes in PD patients versus asymptomatic subjects, all carriers of deleterious variants in GBA.MethodsWe used a custom next‐generation sequencing panel, including 50 LSD genes, to screen 305 patients and 207 controls (discovery cohort). Replication and meta‐analysis were performed in two replication cohorts of GBA‐variant carriers, of 250 patients and 287 controls, for whom exome or genome data were available.ResultsStatistical analysis in the discovery cohort revealed a significantly increased burden of deleterious variants in LSD genes in patients (P = 0.0029). Moreover, our analyses evidenced that the two strongest modifiers of GBA penetrance are a second variation in GBA (5.6% vs. 1.4%, P = 0.023) and variants in genes causing mucopolysaccharidoses (6.9% vs. 1%, P = 0.0020). These results were confirmed in the meta‐analysis, where we observed pooled odds ratios of 1.42 (95% confidence interval [CI] = 1.10–1.83, P = 0.0063), 4.36 (95% CI = 2.02–9.45, P = 0.00019), and 1.83 (95% CI = 1.04–3.22, P = 0.038) for variants in LSD genes, GBA, and mucopolysaccharidosis genes, respectively.ConclusionThe identification of genetic lesions in lysosomal genes increasing PD risk may have important implications in terms of patient stratification for future therapeutic trials. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson Movement Disorder Society.

Pharmacokinetics and biomarker responses in patients with Gaucher disease type 3 or GBA-associated Parkinson's disease treated with venglustat

Pharmacokinetics and biomarker responses in patients with Gaucher disease type 3 or GBA-associated Parkinson's disease treated with venglustat

Generation of induced pluripotent stem cell line, ICGi034-A, by reprogramming peripheral blood mononuclear cells from a patient with Parkinson’s disease associated with GBA mutation

Mutation in the glucocerebrosidase encoding gene (GBA) is one of the most frequent genetic cause of Parkinson's disease. ICGi034-A induced pluripotent stem cell (iPSC) line obtained by reprogramming peripheral blood mononuclear cells (PBMCs) of a patient with heterozygous c.1226A > G (p.N370S) mutation in the GBA gene can be used for studying the fundamental mechanisms of the pathogenesis of GBA-associated Parkinson's disease, and for potential drug screening. The iPSCs express pluripotency markers (NANOG, SSEA4, TRA-1-60, OCT4, SOX2), have a normal karyotype, and are capable of producing derivatives of three germ layers.

P.0730 Alteration of lysosomal activities associate with disturbance of alpha-synuclein protein level in blood of patients with GBA-associated parkinson's disease

P.0730 Alteration of lysosomal activities associate with disturbance of alpha-synuclein protein level in blood of patients with GBA-associated parkinson's disease

Alteration of expression levels of genes involved in maintaining dopaminergic system as trigger for GBA-associated Parkinson's disease

Introduction. Mutations in the GBA gene are the major genetic risk factor for Parkinson's disease (PD), neurodegenerative movement disorder that affects dopaminergic neurons. Not all carriers of GBA mutations (GBA-Carriers) develop PD during their lives. We supposed association of development of PD among GBA-carriers with more pronounced changes in expression levels of genes involved in the maintenance of dopaminergic neurons than in sporadic PD. The aim was to estimate expression levels of JUNB, NR4A2, SLC18A2, EGR1 genes in GBA-PD patients, GBA-carriers, PD patients and controls.

Association of gender and age at onset with glucocerebrosidase associated Parkinson's disease: a systematic review and meta-analysis.

Glucocerebrosidase (GBA) gene has been proved to be a risk factor for the development of Parkinson's disease (PD). However, the gender effect in the prevalence of GBA-associated PD (GBA-PD) is still controversial. And there is no conclusion whether the age at onset (AAO) of PD is different between carriers and non-carriers of GBA. To clarify the association between gender and AAO in GBA-PD, we conducted a systematic review and meta-analysis. PubMed, Web of Science, and Embase were retrieved to obtain potentially related studies. The odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to determine the association between gender and GBA-PD. And the weighted mean difference (WMD) with 95% CIs was employed to assess the difference of AAO between carriers and non-carriers of GBA. A total of twenty-eight studies involving 16,488 PD patients were included in this meta-analysis. The results showed the prevalence of female patients was higher in GBA-PD [OR: 1.19, (95% CI, 1.07-1.32), P = 0.001]. Meanwhile, GBA carriers had younger age at PD onset than GBA non-carriers [WMD: 2.87, (95% CI, 2.48-3.27), P < 0.001]. Results of subgroup analysis showed the prevalence of women in GBA-PD was higher than men in North American and European PD patients, while the gender difference was not significant in other areas around the world, suggesting an ethnic specificity of gender effect for GBA-PD. Our results indicate the higher female prevalence with ethnic specificity and younger AAO of GBA carriers in GBA-PD.

P.101 Involvement of the genes related to lysosomal storage disorders in GBA-associated Parkinson's disease

P.101 Involvement of the genes related to lysosomal storage disorders in GBA-associated Parkinson's disease

P.114 Contribution of the SNCA gene and genes involved in autophagy in the pathogenesis of GBA-associated parkinson's disease

P.114 Contribution of the SNCA gene and genes involved in autophagy in the pathogenesis of GBA-associated parkinson's disease

Neuroimaging, genetic, and enzymatic study in a Japanese family with a GBA gross deletion

IntroductionGlucocerebrosidase gene (GBA) variants are associated with Parkinson's disease (PD) and dementia with Lewy bodies (DLB). The molecular mechanisms underlying these diseases with GBA variants, however, are not well understood. In order to determine the effect of a deletion mutation in GBA, we performed a neuroimaging, genetic, and enzymatic study in a Japanese family with a gross deletion of exons 3 to 11 in GBA. MethodsWe performed [123I] FP-CIT SPECT and [123I] N-isopropyl-p-iodoamphetamine SPECT (IMP-SPECT), and determined GBA expression and glucocerebrosidase (GCase) activity in leukocytes in two GBA-associated PD patients and nine unaffected individuals (including four mutation carriers) in a Japanese family with a heterozygous gross deletion mutation in the GBA gene. ResultsThe two PD patients and two of the four clinically unaffected carriers showed decreased [123I] FP-CIT uptake. IMP-SPECT showed a pattern like that in DLB in one patient. When we compared PD patients with GBA mutations with clinically unaffected carriers, there was a poor correlation between the development of PD and the expression level of GBA or GCase activity. ConclusionWe confirmed the gross deletion mutation in the GBA gene, which appeared to be associated with the PD or reduced [123I] FP-CIT in this family. However, since we cannot conclude whether a reduction of GCase activity is directly correlated with the pathogenesis of PD or not, longitudinal follow-up of this family is needed.

Patient's perception: shorter and more severe prodromal phase in GBA-associated PD.

Prevalence and time of occurrence of prodromal symptoms of Parkinson's disease (PD) in relation to the onset of classical motor manifestation varies between patients. Possible modifying factors might be different genetic architectures predisposing to varying burden of manifestations. To characterize the prodromal phase in PD patients with heterozygous mutations in the GBA gene compared to PD patients without GBA mutation. In a retrospective design, 151 participants [47 PD patients carrying a GBA mutation (PDGBA ), 52 idiopathic PD patients (PDidiopathic ), 52 healthy elderly (CON)] underwent a validated structured interview designed to assess prevalence and time of occurrence of prodromal symptoms. PDGBA showed a higher prevalence of prodromal symptoms and almost simultaneous occurrence of non-motor and early motor symptoms shortly before PD diagnosis whereas PDidiopathic reported a longer prodromal phase starting with non-motor symptoms. The short and severe prodromal phase in PDGBA might call for shorter assessment intervals in yet premanifest GBA mutation carriers.

Increased yield of full GBA sequencing in Ashkenazi Jews with Parkinson's disease

BackgroundVariants in GBA are the most common genetic risk factor for Parkinson's disease (PD), and are especially prevalent in the Ashkenazi Jewish (AJ) population. However, most studies on GBA in AJ genotype only seven selected Gaucher-associated pathogenic variants rather than sequencing the whole gene, which may leave carriers of PD-associated GBA variants undiscovered. MethodsGBA was fully sequenced using molecular inversion probes (MIPs) and Sanger sequencing in 735 AJ PD patients and 662 AJ controls, from Israel and New York. Additional AJ control data (n = 3044) from the Inflammatory Bowel Disease Exome Portal was used. ResultsFull GBA sequencing increased the number of variants discovered by 17.4%, compared to targeted genotyping. An additional 17 PD patients were identified with GBA-associated PD. The p.E326K variant was found in 1.6% of AJ PD patients, making it the second most common PD-associated GBA variant in AJ. GBA variants were found in 18% of PD patients and 7.5% of controls (OR = 2.7, 95%CI = 1.9–3.8, p < 0.0001). ConclusionWithout full sequencing of GBA, or at minimum including p.E326K in the genotyping panel, a significant proportion of variant carriers go undiscovered and may be incorrectly assigned as non-carriers in studies or clinical trials.

Phenotypic Characteristics in GBA-Associated Parkinson's Disease: A Study in a Greek Population.

We compared phenotypic characteristics in 35 Greek patients with Parkinson's disease (PD), carriers of GBA1 mutations (GBA-PD), with 35 Genetically Unidentified PD patients (GU-PD). We found a previously reported higher prevalence of cognitive impairment and a little appreciated more frequent bilateral onset of the disease in GBA-PD vs GU-PD. As far as the exposure to environmental factors, linked to PD, is concerned, our study hints to the possibility that pesticide exposure may be more common in GBA-PD patients, and possibly act synergistically with the mutation carrier status to trigger the disease.

Evaluation of glucosyl ceramide synthase (GCS) inhibition for GBA-associated Parkinson disease

Evaluation of glucosyl ceramide synthase (GCS) inhibition for GBA-associated Parkinson disease

Serum lipid alterations in GBA-associated Parkinson's disease

IntroductionMutations in the GBA gene, encoding for the lysosomal enzyme glucocerebrosidase, are associated with Gaucher disease. Alterations in plasma sphingolipids have been reported in Gaucher, and similarly in brain extracts in Lewy body disease. As GBA mutations are prevalent risk factors for Parkinson's disease and overlap of molecular pathways are presumable, here we assessed the lipid profiles in Parkinson's patients with and without GBA mutations. MethodsWe sequenced all GBA exons in 415 Parkinson's patients, previously genotyped for LRRK2. 64 patients (29 GBA positive vs. 35 non-GBA-carriers including 18 LRRK2 positive and 17 non-mutated) were analyzed for chitotriosidase activity and for the concentration of 40 lipid classes using HPLC-MS. Results29/415 patients (6.9%) carried 8 different GBA mutations associated with Gaucher or Parkinson's, including one novel mutation. Chitotriosidase activity was similar across the genetic groups, while the levels of key lipids were altered in GBA mutation carriers: Monohexosylceramide, Ceramide and Sphingomyelin were elevated; while Phosphatidic acid (PA), Phosphatidylethanolamine (PE), Plasmalogen phosphatidylethanolamine (PEp) and Acyl Phosphatidylglycerol (AcylPG) were decreased. ConclusionThe results suggest an important role for these lipids in GBA mediated Parkinson's disease and assist in the identification of common pathways between Gaucher and Parkinson's. Ultimately, our findings may lead to the identification of novel biomarkers for individuals at increased risk of developing Parkinson's disease.

Glucosylsphingosine Promotes α-Synuclein Pathology in Mutant GBA-Associated Parkinson's Disease.

Glucocerebrosidase 1 (GBA) mutations responsible for Gaucher disease (GD) are the most common genetic risk factor for Parkinson's disease (PD). Although the genetic link between GD and PD is well established, the underlying molecular mechanism(s) are not well understood. We propose that glucosylsphingosine, a sphingolipid accumulating in GD, mediates PD pathology in GBA-associated PD. We show that, whereas GD-related sphingolipids (glucosylceramide, glucosylsphingosine, sphingosine, sphingosine-1-phosphate) promote α-synuclein aggregation in vitro, glucosylsphingosine triggers the formation of oligomeric α-synuclein species capable of templating in human cells and neurons. Using newly generated GD/PD mouse lines of either sex [Gba mutant (N370S, L444P, KO) crossed to α-synuclein transgenics], we show that Gba mutations predispose to PD through a loss-of-function mechanism. We further demonstrate that glucosylsphingosine specifically accumulates in young GD/PD mouse brain. With age, brains exhibit glucosylceramide accumulations colocalized with α-synuclein pathology. These findings indicate that glucosylsphingosine promotes pathological aggregation of α-synuclein, increasing PD risk in GD patients and carriers.SIGNIFICANCE STATEMENT Parkinson's disease (PD) is a prevalent neurodegenerative disorder in the aging population. Glucocerebrosidase 1 mutations, which cause Gaucher disease, are the most common genetic risk factor for PD, underscoring the importance of delineating the mechanisms underlying mutant GBA-associated PD. We show that lipids accumulating in Gaucher disease, especially glucosylsphingosine, play a key role in PD pathology in the brain. These data indicate that ASAH1 (acid ceramidase 1) and GBA2 (glucocerebrosidase 2) enzymes that mediate glucosylsphingosine production and metabolism are attractive therapeutic targets for treating mutant GBA-associated PD.