Glucosidase Beta Acid Research Articles

The GBA1 K198E Variant Is Associated with Suppression of Glucocerebrosidase Activity, Autophagy Impairment, Oxidative Stress, Mitochondrial Damage, and Apoptosis in Skin Fibroblasts.

Parkinson's disease (PD) is a multifactorial, chronic, and progressive neurodegenerative disorder inducing movement alterations as a result of the loss of dopaminergic (DAergic) neurons of the pars compacta in the substantia nigra and protein aggregates of alpha synuclein (α-Syn). Although its etiopathology agent has not yet been clearly established, environmental and genetic factors have been suggested as the major contributors to the disease. Mutations in the glucosidase beta acid 1 (GBA1) gene, which encodes the lysosomal glucosylceramidase (GCase) enzyme, are one of the major genetic risks for PD. We found that the GBA1 K198E fibroblasts but not WT fibroblasts showed reduced catalytic activity of heterozygous mutant GCase by -70% but its expression levels increased by 3.68-fold; increased the acidification of autophagy vacuoles (e.g., autophagosomes, lysosomes, and autolysosomes) by +1600%; augmented the expression of autophagosome protein Beclin-1 (+133%) and LC3-II (+750%), and lysosomal-autophagosome fusion protein LAMP-2 (+107%); increased the accumulation of lysosomes (+400%); decreased the mitochondrial membrane potential (∆Ψm) by -19% but the expression of Parkin protein remained unperturbed; increased the oxidized DJ-1Cys106-SOH by +900%, as evidence of oxidative stress; increased phosphorylated LRRK2 at Ser935 (+1050%) along with phosphorylated α-synuclein (α-Syn) at pathological residue Ser129 (+1200%); increased the executer apoptotic protein caspase 3 (cleaved caspase 3) by +733%. Although exposure of WT fibroblasts to environmental neutoxin rotenone (ROT, 1 μM) exacerbated the autophagy-lysosomal system, oxidative stress, and apoptosis markers, ROT moderately increased those markers in GBA1 K198E fibroblasts. We concluded that the K198E mutation endogenously primes skin fibroblasts toward autophagy dysfunction, OS, and apoptosis. Our findings suggest that the GBA1 K198E fibroblasts are biochemically and molecularly equivalent to the response of WT GBA1 fibroblasts exposed to ROT.

Clinicogenetic Profile, Treatment Modalities, and Mortality Predictors of Gaucher Disease: A 15-Year Retrospective Study

Introduction: Gaucher disease (GD) is a rare autosomal recessive lysosomal storage disorder, in which biallelic pathogenic variants in the Glucosidase beta acid (GBA) gene result in defective functioning of glucosylceramidase that causes deposition of glucocerebroside in cells. GD has 3 major types namely, non-neuronopathic (type I), acute neuronopathic (type II), and chronic neuronopathic (type III). Definite treatment options are limited and expensive. They succumb early to the disease, if untreated. There is paucity of studies from the Indian subcontinent, which elicit the factors resulting in their premature mortality. Materials and Methods: A retrospective study was carried out in a tertiary care setting of South India to assess the clinical profile, mutation spectrum, and various management strategies (only supportive therapy, enzyme replacement therapy [ERT], substrate reduction therapy [SRT] haematopoietic stem cell transplant [HSCT]), and mortality predictors of patients with GD from 2004 to 2019. A Kaplan-Meier survival curve was plotted. In silico predictions were performed for novel variants. Results: There were 60 patients with all types of GD seen over the study period of 15 years. Their median age at diagnosis was 2 years. The median follow-up was for 5 years (interquartile range [IQR] = 2–8). The overall mortality rate was 35%; however, it was only 10% in those receiving definite treatment. Mortality was higher (47.5%) by more than 4 folds in those only on supportive therapy. The median survival from the time of diagnosis was 6.3 years (IQR = 3.5–10.8) in the definite treatment group and 3.5 years (IQR = 1–5) in those on supportive therapy. The Kaplan-Meier survival analysis showed significant (p value 0.001) mortality difference between these groups. The multiple logistic regression analysis found the neuronopathic type (OR = 5) and only supportive therapy (OR = 6.3) to be the independent risk factors for premature mortality. Conclusion: GD is a rare disease with a high mortality rate, if left untreated. ERT and SRT are the definitive treatments which increase the survival. In resource-limited settings like India, with higher prevalence of the neuronopathic type, HSCT may be a more suitable definitive treatment option, due to its one-time intervention and cost, assuming similar efficacy to ERT. However, the efficacy and safety of HSCT in GD needs to be established further by substantial patient numbers undergoing it.

Correction of pathology in mice displaying Gaucher disease type 1 by a clinically-applicable lentiviral vector

Gaucher disease type 1 (GD1) is an inherited lysosomal disorder with multisystemic effects in patients. Hallmark symptoms include hepatosplenomegaly, cytopenias, and bone disease with varying degrees of severity. Mutations in a single gene, glucosidase beta acid 1 (GBA1), are the underlying cause for the disorder, resulting in insufficient activity of the enzyme glucocerebrosidase, which in turn leads to a progressive accumulation of the lipid component glucocerebroside. In this study, we treat mice with signs consistent with GD1, with hematopoietic stem/progenitor cells transduced with a lentiviral vector containing an RNA transcript that, after reverse transcription, results in codon-optimized cDNA that, upon its integration into the genome encodes for functional human glucocerebrosidase. Five months after gene transfer, a highly significant reduction in glucocerebroside accumulation with subsequent reversal of hepatosplenomegaly, restoration of blood parameters, and a tendency of increased bone mass and density was evident in vector-treated mice compared to non-treated controls. Furthermore, histopathology revealed a prominent reduction of Gaucher cell infiltration after gene therapy. The vector displayed an oligoclonal distribution pattern but with no sign of vector-induced clonal dominance and a typical lentiviral vector integration profile. Cumulatively, our findings support the initiation of the first clinical trial for GD1 using the lentiviral vector described here.

Modeling Parkinson's Disease Using Induced Pluripotent Stem Cells.

Parkinson's disease (PD) is the second most common neurodegenerative disease. The molecular mechanisms of PD at the cellular level involve oxidative stress, mitochondrial dysfunction, autophagy, axonal transport, and neuroinflammation. Induced pluripotent stem cells (iPSCs) with patient-specific genetic background are capable of directed differentiation into dopaminergic neurons. Cell models based on iPSCs are powerful tools for studying the molecular mechanisms of PD. The iPSCs used for PD studies were mainly from patients carrying mutations in synuclein alpha (SNCA), leucine-rich repeat kinase 2 (LRRK2), PTEN-induced putative kinase 1 (PINK1), parkin RBR E3 ubiquitin protein ligase (PARK2), cytoplasmic protein sorting 35 (VPS35), and variants in glucosidase beta acid (GBA). In this review, we summarized the advances in molecular mechanisms of Parkinson's disease using iPSC models.

Deep Brain Stimulation in Patients With Mutations in Parkinson's Disease-Related Genes: A Systematic Review.

Deep brain stimulation (DBS) is an effective treatment for Parkinson's disease (PD), and careful selection of candidates is a key component of successful therapy. Although it is recognized that factors such as age, disease duration, and levodopa responsiveness can influence outcomes, it is unclear whether genetic background should also serve as a parameter. The aim of this systematic review is to explore studies that have evaluated DBS in patients with mutations in PD-related genes. We performed a selective literature search for articles regarding the effects of DBS in autosomal dominant or recessive forms of PD or in PD patients with genetic risk factors. Data regarding changes in motor and nonmotor scores and the presence of adverse events after the stimulation were collected. A total of 25 studies were included in the systematic review, comprising 135 patients. In the shorter term, most patients showed marked or satisfactory response to subthalamic DBS, although leucine rich repeat kinase 2 carriers of R114G mutations had higher rates of unsatisfactory outcome. Longer term follow-up data were scarce but suggested that motor benefit is sustained. Patients with the glucosidase beta acid (GBA) mutation showed higher rates of cognitive decline after surgery. Motor outcome was scarce for pallidal DBS. Few adverse events were reported. Subthalamic DBS results in positive outcomes in the short term in patients with Parkin, GBA, and leucine-rich repeat kinase 2 (non-R144G) mutations, although the small sample size limits the interpretation of our findings. Longer and larger cohorts of follow-up, with broader nonmotor symptom evaluations will be necessary to better customize DBS therapy in this population.

M30 - NEXT-GENERATION RNA SEQUENCING OF POST-MORTEM ANTERIOR CINGULATE AND DORSOLATERAL PREFRONTAL CORTICES TO IDENTIFY DIFFERENTIALLY EXPRESSED GENES IN PATHOLOGY-VERIFIED LEWY BODY DEMENTIA

Background Lewy Body Dementias (LBD) include Dementia with Lewy Bodies (DLB) and Parkinson's Disease Dementia (PDD). DLB is the second most common neurodegenerative dementia, and it is associated with increased mortality, earlier nursing home admissions, higher risk of falls, poorer quality-of-life, more health resource utilisation, higher costs, and more caregivers’ burden than Alzheimer's disease. There are no disease-modifying treatments for LBD, and reliable cost-effective biomarkers that can aid early diagnosis of LBD remain elusive. Identifying Differentially Expressed Genes (DEG) in LBD brains can reveal underlying functionally disrupted molecular pathways, and it may lead to novel biomarkers and potential RNA drugs for LBD. However, relevant studies investigating transcriptomics of LBD remain sparse. Methods We studied anterior cingulate and dorsolateral prefrontal cortices of post-mortem pathology-verified brains from the following three groups, (i) DLB (n=7), (ii) PDD (n=7), and (iii) non-demented older people (n=6). Total RNA was extracted, and their quality was assessed by Agilent 2100 Bioanalyzer (N=40). Next-generation RNA-sequencing (RNA-seq) (75 bp; paired-end; minimum 30 million clean reads/ sample) was completed using Illumina HiSeq-4000. After appropriate quality control, reads were aligned to the human genome by HISAT2. Aligned reads were counted by featureCounts, and DEG were identified by edgeR 3.18.1 with Benjamini-Hochberg false discovery correction (5%). Functional analyses of identified DEGs were performed using Ingenuity Pathway Analysis. Subgroup analyses were performed between LBD with and without pathogenic GBA (Glucosidase, Beta Acid) mutations. Results We have identified specific significantly upregulated and downregulated DEGs in LBD, while comparing with non-demented older people. Downregulated DEGs in LBD include Oxytocin Receptor (OXTR), Myeloperoxidase (MPO), Selectin E (SELE), Cathepsin G (CTSG), and Somatostatin (SST), and upregulated DEGs in LBD include X-Inactive Specific Transcript (XIST), Polypeptide N-acetyl galactosaminyl transferase 6 (GALNT6), and mitochondrial Proline dehydrogenase (PRODH). DEGs in LBD are significantly enriched for prion diseases, cytokine-cytokine receptor interaction, phagosome, and glycerophospholipid metabolism pathways. We have also identified the DEGs that significantly differ between DLB and PDD, and the transcriptomic differences between the two cortical regions. Discussion Although this has been an explorative study, this is the hitherto largest RNA-seq study investigating the transcriptomics of pathology-verified LBD brains. In addition to enhancing our understanding of LBD neurobiology at molecular level, this study has identified specific RNA targets that may be novel biomarkers and therapeutic targets for DLB and PDD. Further replication experiments, and more bioinformatic analyses of our data are on-going. We are currently investigating serum exosomal RNA cargo of people with LBD for evaluating the peripheral biomarker potential of identified DEGs. Translational relevance and therapeutic potential of identified DEGs will be evaluated by in-vitro experiments.

Genetic and clinical characteristics of Filipino patients with Gaucher disease

Gaucher disease (GD) is a lysosomal storage disorder caused by the deficiency of the β-glucocerebrosidase enzyme due to disease causing mutations in the GBA1 (glucosidase beta acid) gene, leading to the abnormal accumulation of the lipid glucocerebroside in lysosomal macrophages. This is a review of the clinical features and molecular profiles of 14 Filipino patients with GD. Five patients presented with type 1 disease, two had type 2 GD and seven had type 3 GD. The age of onset for all types was between 1 and 2 years of age but there was a delay of 2.2 years from the time of symptom onset to confirmation of diagnosis. Hepatosplenomegaly, anemia and thrombocytopenia were present in most of the patients. Stunting was seen in 64.3% and bone abnormalities were present in 63.6%. The most common mutant allele detected in this cohort was L483P (previously L444P), followed by F252I, P358A and G241R. IVS2+1 G>A, N409S and G416S mutations were reported singularly. There were 3 patients who were found to have N131S mutations and one patient with D257V mutation, mutant alleles that have only been reported among the Filipinos to date. Except for N409S, the mutations found in this cohort were generally severe and were congruent with the severe phenotypes found in most patients. Of the 14 patients, only 6 were able to undergo enzyme replacement therapy which significantly improved the hematologic parameters and decreased the sizes of the liver and spleen but did not consistently improve the growth and skeletal abnormalities nor alleviate the neurological manifestations of our patients with GD. Improved monitoring through recommended modalities for assessments and tools for evaluation should be implemented in order to fully appreciate the severity of the disease and accuracy of the response to treatment.

GBA-Associated Parkinson's Disease: Progression in a Deep Brain Stimulation Cohort.

Recent evidence suggests that glucosidase beta acid (GBA) mutations predispose Parkinson's disease (PD) patients to a greater burden of cognitive impairment and non-motor symptoms. This emerging knowledge has not yet been considered in patients who have undergone deep brain stimulation (DBS); a surgery that is generally contraindicated in those with cognitive deficits. To explore the long-term phenotypic progression of GBA-associated PD, in a DBS cohort. Thirty-four PD patients who had undergone DBS surgery between 2002 and 2011 were included in this study; 17 patients with GBA mutations were matched to 17 non-carriers. Clinical evaluation involved the administration of four assessments: The Mattis Dementia Rating Scale was used to assess cognitive function; non-motor symptoms were assessed using the Non-Motor Symptom Assessment Scale for PD; quality of life was measured using the Parkinson's Disease Questionnaire; and motor symptoms were evaluated using part III of the Movement Disorders Society Unified Parkinson's Disease Rating Scale, in on-medication/on-stimulation conditions. Levodopa equivalent doses (LED) and DBS settings were compared with clinical outcomes. At a mean follow-up of 7.5 years after DBS, cognitive impairment was more prevalent (70% vs 19%) and more severe in GBA mutation carriers compared to non-carriers (60% vs 6% were severely impaired). Non-motor symptoms were also more severe and quality of life more impaired in GBA-associated PD. Motor symptoms, LED, and stimulation settings were not significantly different between groups at follow-up. GBA status appears to be an important predictor for non-motor symptom disease progression, after deep brain stimulation surgery.

Gaucher-Associated Parkinsonism

Gaucher disease is associated with Parkinson’s disease (PD) by mutations in glucocerebrosidase (GCase). The gene encoding GCase, glucosidase beta acid (GBA), is an important risk factor for PD. Findings from large studies have shown that patients with PD have an increased frequency of mutations in GBA and that GBA mutation carriers exhibit diverse parkinsonian phenotypes and Lewy body pathology. Although the mechanism for this association remains elusive, some hypotheses have been proposed to explain it, including gain of function caused by GBA mutations, which increases α-synuclein (α-syn) aggregation, loss of function due to lysosomal enzyme deficiency, which affects α-syn clearance, and even a bidirectional feedback loop, but each of these hypotheses has its limitations. It is also worth noting that many findings have implicated the interaction between α-syn and GCase, indicating the essential role of the interaction in the pathogenesis of GBA-associated parkinsonism. Therefore, the current review focuses on α-syn and GCase, and it provides some new thoughts that may be helpful for understanding the α-syn-GCase interaction and unraveling the exact mechanism underlying GBA-associated parkinsonism.

Gaucher disease in Syrian children: common mutations identification, and clinical futures.

BACKGROUND AND OBJECTIVESGaucher disease (GD) is caused by the deficiency of glucosidase beta acid (GBA). Three clinical forms of GD are available. Some mutations in the GBA gene have a high frequency in specific populations. The aim of this study was to analyze the characteristics of phenotypes and genotypes of GD in Syrian pediatric patients and assess whether a genotype-phenotype relationship could be helpful in treatment decision-making.DESIGN AND SETTINGSA cross-sectional clinical genetic study of 19 Syrian children admitted to Children’s Hospital, Damascus University.PATIENTS AND METHODSNineteen Syrian children with GD were enrolled in the study; DNA was extracted from peripheral blood leukocytes. The GBA gene was amplified by polymerase chain reaction, and the 9 most common mutations were studied using a Gaucher Disease Strip Assay (ViennaLab Diagnostics GmbH, Vienna, Austria).RESULTSThe majority of children had an early age of onset. A total of 17 patients presented severe hematological and skeletal complications. Neurological involvement was encountered in 2 patients. Twelve patients (63, 2%) were homozygous for the L444P mutation, 1 patient (5.3%) was homozygous for the N370S mutation, and 1 patient (5.3%) was heterozygous for the N370S mutation. Five patients (26.3%) had unknown mutations.CONCLUSIONL444P/L444P was the most common genotype in the studied patients. GD3 with severe visceral presentation in childhood was the dominant phenotype; N370S was found in the heterozygote state in 1 case and in the homozygote state in 1 case. This phenotype and genotype pattern is encountered in the Middle East. There was no genotype-phenotype correlation.

Differential effects of severe vs mild GBA mutations on Parkinson disease.

To better define the genotype-phenotype correlations between the type of GBA (glucosidase, beta, acid) mutation, severe or mild, and the risk and age at onset (AAO), and potential mechanism of Parkinson disease (PD). We analyzed 1,000 patients of Ashkenazi-Jewish descent with PD for 7 founder GBA mutations, and conducted a meta-analysis of risk and AAO according to GBA genotype (severe or mild mutation). The meta-analysis included 11,453 patients with PD and 14,565 controls from worldwide populations. The statistical analysis was done with and without continuity correction (constant or empirical), considering biases that could potentially affect the results. Among Ashkenazi-Jewish patients with PD, the odds ratios for PD were 2.2 and 10.3 for mild and severe GBA mutation carriers, respectively. The observed frequency of severe GBA mutation carriers among patients with PD was more than 4-fold than expected (4.4% vs 0.9%, respectively, p < 0.0001, Fisher exact test). In the different models of the meta-analysis, the odds ratios for PD ranged between 2.84 and 4.94 for mild GBA mutation carriers and 9.92 and 21.29 for severe GBA mutation carriers (p < 1 × 10(-6) for all analyses). Pooled analysis demonstrated AAO of 53.1 (±11.2) and 58.1 (±10.6) years for severe and mild GBA mutation carriers, respectively (p = 4.3 × 10(-5)). These data demonstrate that mild and severe heterozygous GBA mutations differentially affect the risk and the AAO of PD. Our results have important implications for genetic counseling and clinical follow-up.

Increased glucocerebrosidase expression and activity in preeclamptic placenta

IntroductionLysosomal glucosidase beta acid (GBA) deficiency is inherent to Gaucher disease, Parkinsonism and Lewy-body dementia. Increased GBA expression has never been associated with human disease. We describe increased GBA expression and activity in placenta from preeclamptic pregnancies. Methods112 placenta biopsies were available for qPCR, analysis of GBA gene expression and activity. Microanalysis was performed on 20 placenta samples. Alternatively spliced placental GBA transcripts were cloned, expressed in HEK293 cells and analyzed by Western blot and activity assay. ResultsGBA is expressed in the syncytiotrophoblast layer of human placenta already at 5 weeks of gestation. We identified five novel GBA transcripts in placenta that enzymatically inactive when expressed in HEK293 cells. Both GBA RNA expression and enzymatic activity are upregulated in preeclamptic placenta. Microarray analysis of 20 placenta tissues identified 158 genes co-regulating with GBA expression and gene enrichment analysis highlights lysosomal function. In our micro-array data GBA expression does not correlate with FLT1 expression, currently the most powerful marker for preeclampsia. There are 89 transcripts that are negatively correlated with GBA expression of which BMP4 and TFEB are interesting as they are essential to early placenta function. DiscussionAlthough very speculative, we hypothesize that increased GBA expression might relate to placentation through decreased BMP4 signaling or vascularization through downregulation of TFEB. Ceramide, the product of hydrolysis of glucosylceramide by GBA and involved in the regulation of cell differentiation, survival and apoptosis, is another putative candidate linking increased GBA activity to preeclampsia. Both pathways merit further investigation.

Cognitive and Antipsychotic Medication Use in Monoallelic GBA-Related Parkinson Disease.

Mutations in glucosidase, beta, acid (GBA) are associated with cognitive impairment in Parkinson disease (PD) as well as dementia with Lewy bodies. For both of these diseases, dementia and hallucinations are typically treated with cholinesterase inhibitors and antipsychotics. However, in some lysosomal storage disorders certain antipsychotic medications are poorly tolerated. This study examined cholinesterase inhibitor and antipsychotic use in monoallelic GBA-related PD to explore potential pharmacogenetic relationships. Monoallelic GBA mutation carriers with PD (GBA-PD) with at least two clinic visits (n = 34) were matched for age-of-onset and gender to GBA and leucine-rich repeat kinase 2 (LRRK2) mutation negative idiopathic PD subjects (IPD) (n = 60). Information regarding cholinesterase inhibitor and antipsychotic use as well as impaired cognition (UPDRS Mentation >1) and hallucinations (UPDRS Thought Disorder >1) were obtained. GBA-PD more frequently reported hallucinations (HR = 5.0; p = 0.01) and they were more likely to have cognitive impairment but this was not statistically significant (HR 2.2, p = 0.07). Antipsychotic use was not significantly different between GBA-PD and IPD (HR = 1.9; p = 0.28), but GBA-PD were more likely to have sustained cholinesterase inhibitor use (HR = 3.1; p = 0.008), even after adjustment for cognition and hallucinations. Consistent with reports of worse cognition, GBA-PD patients are more likely to use cholinesterase inhibitors compared to IPD. While there was no difference in antipsychotic use between IPD and GBA-PD, persistent use of quetiapine in GBA-PD suggests that it is tolerated and that a significant interaction is unlikely. Further prospective study in larger samples with more extensive cognitive assessment is warranted to better understand pharmacogenetic relationships in GBA-PD.

Murine models of acute neuronopathic Gaucher disease

Gaucher disease (GD) is an autosomal recessive lysosomal storage disorder caused by mutations in the glucosidase, beta, acid (GBA) gene that encodes the lysosomal enzyme glucosylceramidase (GCase). GCase deficiency leads to characteristic visceral pathology and, in some patients, lethal neurological manifestations. Here, we report the generation of mouse models with the severe neuronopathic form of GD. To circumvent the lethal skin phenotype observed in several of the previous GCase-deficient animals, we genetically engineered a mouse model with strong reduction in GCase activity in all tissues except the skin. These mice exhibit rapid motor dysfunction associated with severe neurodegeneration and apoptotic cell death within the brain, reminiscent of neuronopathic GD. In addition, we have created a second mouse model, in which GCase deficiency is restricted to neural and glial cell progenitors and progeny. These mice develop similar pathology as the first mouse model, but with a delayed onset and slower disease progression, which indicates that GCase deficiency within microglial cells that are of hematopoietic origin is not the primary determinant of the CNS pathology. These findings also demonstrate that normal microglial cells cannot rescue this neurodegenerative disease. These mouse models have significant implications for the development of therapy for patients with neuronopathic GD.