Correction: Loss of β-Glucocerebrosidase Activity Does Not Affect Alpha-Synuclein Levels or Lysosomal Function in Neuronal Cells.
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ABSTRACT:
SUBMITTER: Dermentzaki G
PROVIDER: S-EPMC8177519 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:To date, a plethora of studies have provided evidence favoring an association between Gaucher disease (GD) and Parkinson's disease (PD). GD, the most common lysosomal storage disorder, results from the diminished activity of the lysosomal enzyme β-glucocerebrosidase (GCase), caused by mutations in the β-glucocerebrosidase gene (GBA). Alpha-synuclein (ASYN), a presynaptic protein, has been strongly implicated in PD pathogenesis. ASYN may in part be degraded by the lysosomes and may itself aberrantly impact lysosomal function. Therefore, a putative link between deficient GCase and ASYN, involving lysosomal dysfunction, has been proposed to be responsible for the risk for PD conferred by GBA mutations. In this current work, we aimed to investigate the effects of pharmacological inhibition of GCase on ASYN accumulation/aggregation, as well as on lysosomal function, in differentiated SH-SY5Y cells and in primary neuronal cultures. Following profound inhibition of the enzyme activity, we did not find significant alterations in ASYN levels, or any changes in the clearance or formation of its oligomeric species. We further observed no significant impairment of the lysosomal degradation machinery. These findings suggest that additional interaction pathways together with aberrant GCase and ASYN must govern this complex relation between GD and PD.
| S-EPMC3620326 | biostudies-literature
Project description:Lysosomal dysfunction is a common pathological feature of neurodegenerative diseases. GTP-binding protein type A1 (GBA1) encodes β-glucocerebrosidase 1 (GCase 1), a lysosomal hydrolase. Homozygous mutations in GBA1 cause Gaucher disease, the most common lysosomal storage disease, while heterozygous mutations are strong risk factors for Parkinson's disease. However, whether loss of GCase 1 activity is sufficient for lysosomal dysfunction has not been clearly determined. Here, we generated human neuroblastoma cell lines with nonsense mutations in the GBA1 gene using zinc-finger nucleases. Depending on the site of mutation, GCase 1 activity was lost or maintained. The cell line with GCase 1 deficiency showed indications of lysosomal dysfunction, such as accumulation of lysosomal substrates, reduced dextran degradation and accumulation of enlarged vacuolar structures. In contrast, the cell line with C-terminal truncation of GCase 1 but with intact GCase 1 activity showed normal lysosomal function. When α-synuclein was overexpressed, accumulation and secretion of insoluble aggregates increased in cells with GCase 1 deficiency but did not change in mutant cells with normal GCase 1 activity. These results demonstrate that loss of GCase 1 activity is sufficient to cause lysosomal dysfunction and accumulation of α-synuclein aggregates.
| S-EPMC4351412 | biostudies-other
Project description:Mutations in the GBA1 gene are the most common genetic risk factor for Parkinson's disease (PD) and dementia with Lewy bodies (DLB). GBA1 encodes the lysosomal lipid hydrolase glucocerebrosidase (GCase), and its activity has been linked to accumulation of ?-synuclein. The current study systematically examines the relationship between GCase activity and both pathogenic and non-pathogenic forms of ?-synuclein in primary hippocampal, cortical, and midbrain neuron and astrocyte cultures, as well as in transgenic mice and a non-transgenic mouse model of PD. We find that reduced GCase activity does not result in aggregation of ?-synuclein. However, in the context of extant misfolded ?-synuclein, GCase activity modulates neuronal susceptibility to pathology. Furthermore, this modulation does not depend on neuron type but rather is driven by the level of pathological ?-synuclein seeds. This study has implications for understanding how GBA1 mutations influence PD pathogenesis and provides a platform for testing novel therapeutics.
| S-EPMC7060125 | biostudies-literature
Project description:Mutations in the GBA1 gene are associated with increased risk of Parkinson's disease, and the protein produced by the gene, glucocerebrosidase, interacts with α-synuclein, the protein at the center of the disease etiology. One possibility is that the mutations disrupt a beneficial interaction between the proteins, and a beneficial interaction would imply that the proteins have coevolved. To explore this possibility, a correlated mutation analysis has been performed for all 72 vertebrate species where complete sequences of α-synuclein and glucocerebrosidase are known. The most highly correlated pair of residue variations is α-synuclein A53T and glucocerebrosidase G115E. Intriguingly, the A53T mutation is a Parkinson's disease risk factor in humans, suggesting the pathology associated with this mutation and interaction with glucocerebrosidase might be connected. Correlations with β-synuclein are also evaluated. To assess the impact of lowered species number on accuracy, intra and inter-chain correlations are also calculated for hemoglobin, using mutual information Z-value and direct coupling analyses.
| S-EPMC4516260 | biostudies-literature
Project description:Pathologic accumulation of alpha-synuclein is a feature of human parkinsonism and other neurodegenerative diseases. This accumulation may be counteracted by mechanisms of protein degradation that have been investigated in vitro but remain to be elucidated in animal models. In this study, lysosomal clearance of alpha-synuclein in vivo was indicated by the detection of alpha-synuclein in the lumen of lysosomes isolated from the mouse midbrain. When neuronal alpha-synuclein expression was enhanced as a result of toxic injury (i.e. treatment of mice with the herbicide paraquat) or transgenic protein overexpression, the intralysosomal content of alpha-synuclein was also significantly increased. This effect was paralleled by a marked elevation of the lysosome-associated membrane protein type 2A (LAMP-2A) and the lysosomal heat shock cognate protein of 70 kDa (hsc70), two essential components of chaperone-mediated autophagy (CMA). Immunofluorescence microscopy revealed an increase in punctate (lysosomal) LAMP-2A staining that co-localized with alpha-synuclein within nigral dopaminergic neurons of paraquat-treated and alpha-synuclein-overexpressing animals. The data provide in vivo evidence of lysosomal degradation of alpha-synuclein under normal conditions and, quite importantly, under conditions of enhanced protein burden. In the latter, increased lysosomal clearance of alpha-synuclein was mediated, at least in part, by CMA induction. It is conceivable that these neuronal mechanisms of protein clearance play an important role in neurodegenerative processes characterized by abnormal alpha-synuclein buildup.
| S-EPMC2859524 | biostudies-literature
Project description:Mutations in GBA, the gene encoding glucocerebrosidase, the lysosomal enzyme deficient in Gaucher disease increase the risk for developing Parkinson disease. Recent research suggests a relationship between glucocerebrosidase and the Parkinson disease-related amyloid-forming protein, α-synuclein; however, the specific molecular mechanisms responsible for association remain elusive. Previously, we showed that α-synuclein and glucocerebrosidase interact selectively under lysosomal conditions, and proposed that this newly identified interaction might influence cellular levels of α-synuclein by either promoting protein degradation and/or preventing aggregation. Here, we demonstrate that membrane-bound α-synuclein interacts with glucocerebrosidase, and that this complex formation inhibits enzyme function. Using site-specific fluorescence and Förster energy transfer probes, we mapped the protein-enzyme interacting regions on unilamellar vesicles. Our data suggest that on the membrane surface, the glucocerebrosidase-α-synuclein interaction involves a larger α-synuclein region compared to that found in solution. In addition, α-synuclein acts as a mixed inhibitor with an apparent IC(50) in the submicromolar range. Importantly, the membrane-bound, α-helical form of α-synuclein is necessary for inhibition. This glucocerebrosidase interaction and inhibition likely contribute to the mechanism underlying GBA-associated parkinsonism.
| S-EPMC3552326 | biostudies-literature
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:Abnormal alpha-synuclein (α-synuclein) expression and aggregation is a key characteristic of Parkinson's disease (PD). However, the exact mechanism(s) linking α-synuclein to the other central feature of PD, dopaminergic neuron loss, remains unclear. Therefore, improved cell and in vivo models are needed to investigate the role of α-synuclein in dopaminergic neuron loss. MicroRNA-7 (miR-7) regulates α-synuclein expression by binding to the 3' UTR of the Synuclein Alpha Non A4 Component of Amyloid Precursor (SNCA) gene and inhibiting its translation. We show that miR-7 is decreased in the substantia nigra of patients with PD and, therefore, may play an essential role in the regulation of α-synuclein expression. Furthermore, we have found that lentiviral-mediated expression of miR-7 complementary binding sites to stably induce a loss of miR-7 function results in an increase in α-synuclein expression in vitro and in vivo. We have also shown that depletion of miR-7 using a miR-decoy produces a loss of nigral dopaminergic neurons accompanied by a reduction of striatal dopamine content. These data suggest that miR-7 has an important role in the regulation of α-synuclein and dopamine physiology and may provide a new paradigm to study the pathology of PD.
| S-EPMC5628933 | biostudies-literature
Project description:Mutations in ATP13A2 (PARK9) cause Kufor-Rakeb syndrome (KRS) characterized by juvenile-onset parkinsonism, pyramidal signs and dementia. PARK9 belongs to type 5 P-type ATPase with its putative function as a cation transporter. Loss of PARK9 leads to lysosomal dysfunction and subsequent ?-synuclein (?-Syn) accumulation. However, the mechanistic link between PARK9 and lysosomal dysfunction remains unclear. Here, we found that patient fibroblasts expressing mutant PARK9 or primary neurons with silenced PARK9 exhibited increased sensitivity to extracellular zinc (Zn(2+)). This effect was rescued with the Zn(2+) chelators clioquinol or TPEN. PARK9-deficient cells showed decreased lysosomal sequestration of Zn(2+) and increased expression of zinc transporters. Importantly, increased concentrations of Zn(2+) (Zn(2+) stress) resulted in lysosomal dysfunction that was partially restored by expression of wild-type PARK9. Zn(2+) stress also caused increased expression of ?-Syn and consequently decreased activity of the lysosomal enzyme glucocerebrosidase. Together, these data suggest that PARK9 loss of function leads to dyshomeostasis of intracellular Zn(2+) that in turn contributes to lysosomal dysfunction and accumulation of ?-Syn. It will be of interest to examine whether therapeutic lowering of zinc may prove beneficial for patients with KRS.
| S-EPMC4014186 | biostudies-literature
Project description:Long noncoding RNAs (lncRNAs) are implicated in the autophagic-lysosomal pathway (ALP) and are closely linked to Parkinson's disease (PD) pathology. β-Glucocerebrosidase (GCase) has also been reported to be correlated with α-synuclein (α-syn) proteostasis. However, lncRNAs and α-syn in neural-derived L1CAM exosomes and GCase activity in the plasma of PD patients have not been studied. This study used an ultrasensitive methodology, fluorescence nanoparticle tracking analysis (NTA), to measure plasma L1CAM exosomes and Quanterix Simoa to measure α-syn concentrations in L1CAM exosomes. Eighty-five healthy controls and 93 PD patients were enrolled, and several scales were used to rate the severity of PD. Receiver operating characteristic (ROC) curves were applied to map the diagnostic accuracy of categorizing PD patients and healthy subjects. We found increased Linc-POU3F3 and α-syn concentrations in L1CAM exosomes and decreased GCase activity in PD patients compared with controls. The three biomarkers displayed obvious differences among PD patients based on gender, H-Y stage, and UPDRS-III distribution. Interestingly, Linc-POU3F3 was significantly positively correlated with α-syn in L1CAM exosomes and inversely correlated with GCase activity in PD patients. Significant correlations were observed among L1CAM exosomal Linc-POU3F3 levels, GCase activity, and PD severity, including motor/cognitive dysfunction. Additionally, the combination of Linc-POU3F3 and α-syn in L1CAM exosomes and GCase activity could discriminate PD patients from controls. These results suggest that L1CAM exosomal Linc-POU3F3, L1CAM exosomal α-syn, and GCase activity may shed light on the mechanism underlying the autophagic-lysosomal system in the pathogenesis of PD and could be used to assess the severity of PD.
| S-EPMC7609611 | biostudies-literature