Mutant glucocerebrosidase impairs alpha-synuclein degradation by blockade of chaperone-mediated autophagy
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA781959 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR16986503.fastq.gz | Fastqsanger.gz | |||
| SRR16986504.fastq.gz | Fastqsanger.gz | |||
| SRR16986505.fastq.gz | Fastqsanger.gz | |||
| SRR16986506.fastq.gz | Fastqsanger.gz | |||
| SRR16986507.fastq.gz | Fastqsanger.gz |
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Project description:The most common genetic risk factors for Parkinson’s disease (PD) are a set of heterozygous mutant (MT) alleles of the GBA1 gene that encodes Beta-glucocerebrosidase (GCase), an enzyme normally trafficked through the ER/ Golgi apparatus to the lysosomal lumen. We found that half of the GCase in lysosomes from post-mortem human GBA-PD brains was present on the lysosomal surface, and that this mislocalization depends on a pentapeptide motif in GCase used to target cytosolic protein for degradation by chaperone-mediated autophagy (CMA). Unfolded mutant GCase at the lysosomal surface inhibits CMA, causing accumulation of CMA substrates including -synuclein. Using single cell transcriptional analysis and comparative proteomics of brains from GBA-PD patients we confirmed reduced CMA activity and proteome changes comparable to those in CMA-deficient mouse brain. Loss of the MT GCase CMA motif is sufficient to rescue primary substantia nigra dopamine neurons from MT-GCase induced neuronal death. We conclude that MT GCase alleles block CMA function and produce -synuclein accumulation.
2022-03-16 | GSE189202 | GEO
Project description:The most common genetic risk factors for Parkinson’s disease (PD) are a set of heterozygous mutant (MT) alleles of the GBA1 gene that encodes -glucocerebrosidase (GCase), an enzyme that is normally trafficked from the endoplasmic reticulum and Golgi apparatus to the lysosomal lumen. We examined isolated lysosomes from anterior cingulate cortex, a region of high alpha-synuclein accumulation in GBA-PD, and found that while lysosomal GCase is entirely luminal in healthy controls, half of the lysosomal GBA-PD GCase was present on the lysosomal surface. This lysosomal mislocalization is dependent on a pentapeptide motif in GCase used for targeting of cytosolic proteins to lysosomes for degradation by chaperone-mediated autophagy (CMA), a type of autophagy inhibited by PD-related pathogenic proteins including -synuclein and LRRK2. Single cell transcriptional analysis and comparative proteomics of brains from GBA-PD patients demonstrated reduced CMA activity and overall proteome changes similar to those observed in mouse models with CMA blockage. We found that the delivery of unfolded mutant GCase to lysosomes decreased CMA due to recognition of unfolded mutant GCase to the chaperone hsc70, and the resulting complex binds the CMA receptor LAMP2A at the lysosomal surface. Unfolded mutant GCase is a poor substrate for translocation into the lysosomal lumen, and by interfering with LAMP2A multimerization, blocks the translocation and causes cytosolic accumulation of other CMA substrates including -synuclein and tau. In primary substantia nigra dopamine neurons, MT GCase led to neuronal death, while loss of the GCase CMA motif or deletion of -synuclein rescued the neurons. These results indicate how MT GCase alleles may converge with other PD proteins to block CMA function and produce -synuclein accumulation.
2022-02-03 | PXD028656 | Pride
Project description:We studied the transcriptomic changes induced by downregulating LAMP2A, key mediator of chaperone-mediated autophagy, in patient-derived glioma stem cells. Overall, 1299 transcripts were significantly downregulated, whereas 1673 appeared to be upregulated. KEGG pathway analysis highlighted PI3K-AKT and p53 signaling and pathways associated with ECM interactions, actin cytoskeleton and focal adhesion as the main altered pathways.
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Project description:Many neurodegenerative disorders including Alzheimer’s disease (AD) and frontotemporal lobar degeneration (FTLD) are characterized by abnormal protein deposition and frequently show comorbid pathology. Progranulin (PGRN) is implicated not only in TDP-43 but in tau and alpha-synuclein proteinopathies. However, the underlying mechanisms are unknown. Here, we generated P301S tau transgenic mice with PGRN haploinsufficiency and loss and found that those mice exhibit exacerbated disinhibition phenotype while showing attenuated memory impairment, hippocampal atrophy, and transcriptomic changes. Remarkably, the phenotypic alteration was accompanied by an increase in tau inclusions, which are positive for alpha-synuclein, a PGRN binding partner beta-glucocerebrosidase (GCase), and its substrate glucosylceramide. GCase inhibition or PGRN deficiency enhanced tau aggregation induced by AD-derived tau seeds in neurons. In vitro, GCase and glucosylceramide promoted P301S tau aggregation. Similar co-pathology was observed in AD and FTLD-GRN patients.
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Project description:Transcriptomic data of downregulated chaperone-mediated autophagy in glioma stem cell activity.
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Project description:While defective α-synuclein homeostasis is central to the pathogenesis of Parkinson’s, fundamental questions about its intracellular trafficking remain unresolved. We have developed a bimolecular fluorescence complementation assay in living cells to monitor de novo ubiquitination of α-synuclein. We identified lysine residues 45, 58 and 60 as critical ubiquitination sites for the degradation of α-synuclein. This is mediated by NBR1 binding to ubiquitinated α-synuclein and entry into endosomes in a process that involves ESCRT I-III complexes for subsequent lysosomal degradation. Autophagy or the autophagic chaperone Hsc70 are dispensable for this pathway. Antibodies against diglycine-modified α-synuclein peptides confirmed that endogenous α-synuclein is similarly ubiquitinated in brain and targeted to the lysosome in rat primary and human iPSC-derived neurons. Ubiquitinated α-synuclein was detected in Lewy bodies and cellular models of aggregation suggesting that it may be entrapped with endo/lysosomes in inclusion bodies. Collectively, our data elucidate the intracellular trafficking of de novo ubiquitinated α-synuclein and provide the tools for investigating the rapidly turned-over fraction of this disease-causing protein.
2023-05-17 | PXD038364 | Pride
Project description:The activity of chaperone-mediated autophagy (CMA), a catabolic pathway for selective degradation of cytosolic proteins in lysosomes, decreases with age, but the consequences of this functional decline in vivo remain unknown. In this work, we have generated a conditional knockout mouse to selectively block CMA in liver. We have found that blockage of CMA causes hepatic glycogen depletion and hepatosteatosis. The liver phenotype is accompanied by reduced peripheral adiposity, increased energy expenditure, and altered glucose homeostasis. Comparative lysosomal proteomics revealed that key enzymes in carbohydrate and lipid metabolism are normally degraded by CMA and that impairment of this regulated degradation contributes to the metabolic abnormalities observed in CMA-defective animals. These findings highlight the involvement of CMA in regulating hepatic metabolism and suggest that the age-related decline in CMA may have a negative impact on the energetic balance of old organisms.
2014-12-31 | GSE49553 | GEO
Project description:Altered degradation of alpha-synuclein (alpha-syn) has been implicated in the pathogenesis of Parkinson disease (PD). We have shown that alpha-syn can be degraded via chaperone-mediated autophagy (CMA), a selective lysosomal mechanism for degradation of cytosolic proteins. Pathogenic mutants of alpha-syn block lysosomal translocation, impairing their own degradation along with that of other CMA substrates. While pathogenic alpha-syn mutations are rare, alpha-syn undergoes posttranslational modifications, which may underlie its accumulation in cytosolic aggregates in most forms of PD. Using mouse ventral medial neuron cultures, SH-SY5Y cells in culture, and isolated mouse lysosomes, we have found that most of these posttranslational modifications of alpha-syn impair degradation of this protein by CMA but do not affect degradation of other substrates. Dopamine-modified alpha-syn, however, is not only poorly degraded by CMA but also blocks degradation of other substrates by this pathway. As blockage of CMA increases cellular vulnerability to stressors, we propose that dopamine-induced autophagic inhibition could explain the selective degeneration of PD dopaminergic neurons.
| S-EPMC2157565 | biostudies-literature
Project description:Mutations in glucocerebrosidase (GBA) are the most prevalent genetic risk factor for Lewy body disorders (LBD) – collectively Parkinson’s disease, Parkinson’s disease dementia and dementia with Lewy bodies. Despite this genetic association, it remains unclear how GBA mutation contributes to the susceptibility of developing LBD. We investigated relationships between LBD-specific glucocerebrosidase deficits, GBA-related pathways, and α-synuclein levels in post-mortem brain tissue from LBD and controls with and without GBA mutations. Our study shows that LBD brains, regardless of GBA mutations, are characterised by altered sphingolipid metabolism, with prominent changes in ceramide species. Since extracellular vesicles (EV) could be involved in LBD pathogenesis by spreading disease linked lipids and proteins, we investigated EV derived from post-mortem cerebrospinal fluid (CSF) and brain tissue from GBA mutation carriers and non-carriers. EV purified from LBD post-mortem CSF and frontal cortex are heavily loaded with ceramides and neurodegeneration-linked proteins including alpha-synuclein and amyloid precursor protein. Our in vitro studies demonstrate that LBD EV constitute a “pathological package” capable of inducing aggregation of wild type alpha-synuclein, potentially through a combination of alpha-synuclein-ceramide interaction and the presence of pathological forms of alpha-synuclein. Together our findings indicate that abnormalities in ceramide metabolism are a feature of LBD, constituting a promising source of biomarkers. GBA mutation likely accelerates the pathological process occurring in sporadic LBD, probably through endolysosomal deficiency, but does not induce alpha-synucleinopathy since healthy normal GBA mutation carriers without alpha-synuclein pathology occur.
2021-11-02 | PXD026980 | Pride
Project description:Molecular chaperones are critical to maintaining intracellular proteostasis and have been shown to have a protective role against alpha-synuclein mediated toxicity. Co-chaperone proteins regulate the activity of molecular chaperones and connect the chaperone network to protein degradation and cell death pathways. Bcl-2 associated athanogene 5 (BAG5) is a co-chaperone that modulates proteostasis by inhibiting the activity of Hsp70 and several E3 ubiquitin ligases, resulting in enhanced neurodegeneration in models of Parkinson’s disease (PD). Here we identify a novel interaction between BAG5 and p62/sequestosome-1 (SQSTM1), suggesting that BAG5 may bridge the chaperone network to autophagy-mediated protein degradation. The interaction was discovered using affinity purifaction followed by mass spectrometry to identify BAG5 interacting proteins and was validated by subsequent in vitro immunoprecipitation studies.
2020-08-05 | PXD019473 | Pride