Biology subjects

Schapira, A. H.

Publications and source records attributed to Schapira, A. H..

5 recordsLinked to original sources

bioRxiv2024

Exploring the relationship between GBA1 host genotype and gut microbiome in the GBA1L444P/WT mouse model: Implications for Parkinson disease pathogenesis

BackgroundHeterozygous variants in GBA1 are the commonest genetic risk factor for Parkinson disease (PD) but penetrance is incomplete. GBA1 dysfunction can cause gastrointestinal disturbances and microbiome changes in preclinical models. Mounting evidence suggests that the microbiota-gut-brain axis is potentially implicated in PD pathogenesis. Whether the gut microbiome composition is influenced by host GBA1 genetics in heterozygosis has never been explored. ObjectivesTo evaluate whether heterozygosity for the GBA1 pathogenic L444P variant can cause perturbations in gut microbiome composition. MethodsFaecal samples collected from GBA1L444P/WT and GBA1WT/WT mice at 3 and 6 months of age were analysed through shotgun metagenomic sequencing. ResultsNo differences in - and {beta}-diversity were detected between genotyped groups, at either time points. Overall, we found a little variation of the gut microbiome composition and functional potential between GBA1L444P/WT and GBA1WT/WT mice over time. ConclusionHost GBA1 genotype does not impact gut microbiome structure and composition in the presented GBA1L444P/WT mouse model. Studies investigating the effect of a second hit on gut physiology and microbiome composition could explain the partial penetrance of GBA1 variants in PD.

neuroscience↗

bioRxiv2024

Simulated microgravity accelerates alpha-synuclein aggregation and induces oxidative stress in an in vitro Parkinson disease model

Parkinsons disease (PD) is a neurodegenerative disorder characterized by the accumulation of alpha-synuclein aggregates and progressive neuronal loss in the substantia nigra, with aging being its primary risk factor. The current available models to study PD mechanisms are largely relying on genetic mutations to recapitulate PD typical hallmarks, such as increased alpha-synuclein aggregation. However, they do not model the aging features associated with the disease. Microgravity, a condition experience by astronauts during space missions, is known to induce ageing-like modifications on both systemic and cellular physiology. To replicate the aging-related stress observed in PD patients, we exposed SH-SY5Y and 3K-SNCA mutant cell lines to simulated microgravity. Our findings revealed that simulated microgravity enhanced PD alterations, with a significant increase in misfolded and phosphorylated a-syn. This was accompanied by heightened oxidative stress, as evidenced by increased levels of reactive oxygen species, without a sufficient antioxidant response. These results suggest that simulated microgravity effectively mimics and accelerate the stress associated with aging in PD cell models, regardless of the presence of PD mutation. This study highlights the potential of simulated microgravity as a tool for investigating aging processes in neurodegenerative diseases.

neuroscience↗

bioRxiv2023

Reduction of a-synuclein aggregates by PIKfyve inhibition via TFEB-mediated lysosomal biogenesis in a Parkinson disease model

Parkinson disease is a neurodegenerative disorder characterised by impairment of motor function, and is associated with a progressive accumulation of insoluble aggregates of misfolded alpha-synuclein. In the present study, we exploited the SH-SY5Y cell model overexpressing a pro-aggregation form of alpha-synuclein to investigate the efficacy of PIKfyve-mediated lysosomal biogenesis, through TFEB, as potential target for Parkinson therapy. To investigate this, we exploited high-content imaging along with enzymatic assays to follow the progression of lysosomal biogenesis, lysosomal function and alpha-synuclein accumulation. The cellular model exploited in this study recapitulated important elements of the biochemical phenotype observed in Parkinson patient-derived neurons, including synuclein aggregates and impaired glucocerebrosidase (GCase) function. PIKfyve inhibition by YM201636 resulted in a lysosomal-dependant reduction of alpha-synuclein aggregates as early as 24 hours post-treatment. The mechanism of action of YM201636 was shown to be TFEB-mediated, with an increase in TFEB in the nuclei which subsequently resulted in increased lysosomal markers LAMP1 and GCase. PIKfyve inhibtion efficacy was also tested in differentiated SH-SY5Y cells, exhibiting a neuron-like morphology. In these cells, YM201636 also significantly reduced alpha-synuclein aggregates and increased TFEB nuclear presence. These findings suggest that PIKfyve inhibition could be exploited as therapeutic target for Parkinson disease.

neuroscience↗

bioRxiv2018

Detection of GBA missense mutations and other variants using the Oxford Nanopore MinION

PurposeMutations in GBA cause Gaucher disease when biallelic, and are strong risk factors for Parkinsons disease when heterozygous. GBA analysis is complicated by the nearby pseudogene. We aimed to design and validate a method for sequencing GBA on the Oxford Nanopore MinION.\n\nMethodsWe sequenced an 8.9 kb amplicon from DNA samples of 17 individuals, including patients with Parkinsons and Gaucher disease, on older and current (R9.4) flow cells. These included samples with known mutations, assessed in a blinded fashion on the R9.4 data. We used NanoOK for quality metrics, two different aligners (Graphmap and NGMLR), Nanopolish and Sniffles to call variants, and Whatshap for phasing.\n\nResultsWe detected all known mutations, including the common p.N409S (N370S) and p.L483P (L444P), and three rarer ones, at the correct zygosity, as well as intronic SNPs. In a sample with the complex RecNciI allele, we detected an additional coding mutation, and a 55-base pair deletion. We confirmed compound heterozygosity where relevant. False positives were easily identified.\n\nConclusionThe Oxford Nanopore MinION can detect missense mutations and an exonic deletion in this difficult gene, with the added advantage of phasing and intronic analysis. It can be used as an efficient diagnostic tool.

genetics↗

bioRxiv2017

DNA isolation protocol effects on nuclear DNA analysis by microarrays, droplet digital PCR, and whole genome sequencing, and on mitochondrial DNA copy number estimation

Potential bias introduced during DNA isolation is inadequately explored, although it could have significant impact on downstream analysis. To investigate this in human brain, we isolated DNA from cerebellum and frontal cortex using spin columns under different conditions, and salting-out. We first analysed DNA using array CGH, which revealed a striking wave pattern suggesting primarily GC-rich cerebellar losses, even against matched frontal cortex DNA, with a similar pattern on a SNP array. The aCGH changes varied with the isolation protocol. Droplet digital PCR of two genes also showed protocol-dependent losses. Whole genome sequencing showed GC-dependent variation in coverage with spin column isolation from cerebellum. We also extracted and sequenced DNA from substantia nigra using salting-out and phenol / chloroform. The mtDNA copy number, assessed by reads mapping to the mitochondrial genome, was higher in substantia nigra when using phenol / chloroform. We thus provide evidence for significant method-dependent bias in DNA isolation from human brain, as reported in rat tissues. This may contribute to array \"waves\", and could affect copy number determination, particularly if mosaicism is being sought, and sequencing coverage. Variations in isolation protocol may also affect apparent mtDNA abundance.

genomics↗