Proteomics-Based Monitoring of Pathway Activity Reveals that Blocking Diacylglycerol Biosynthesis Rescues from Alpha-Synuclein Toxicity.
Ontology highlight
ABSTRACT:
SUBMITTER: Soste M
PROVIDER: S-EPMC6859835 | biostudies-literature |
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:The aggregation of α-synuclein plays a major role in Parkinson disease (PD) pathogenesis. Recent evidence suggests that defects in the autophagy-mediated clearance of α-synuclein contribute to the progressive loss of nigral dopamine neurons. Using an in vivo model of α-synuclein toxicity, we show that the PD-like neurodegenerative changes induced by excess cellular levels of α-synuclein in nigral dopamine neurons are closely linked to a progressive decline in markers of lysosome function, accompanied by cytoplasmic retention of transcription factor EB (TFEB), a major transcriptional regulator of the autophagy-lysosome pathway. The changes in lysosomal function, observed in the rat model as well as in human PD midbrain, were reversed by overexpression of TFEB, which afforded robust neuroprotection via the clearance of α-synuclein oligomers, and were aggravated by microRNA-128-mediated repression of TFEB in both A9 and A10 dopamine neurons. Delayed activation of TFEB function through inhibition of mammalian target of rapamycin blocked α-synuclein induced neurodegeneration and further disease progression. The results provide a mechanistic link between α-synuclein toxicity and impaired TFEB function, and highlight TFEB as a key player in the induction of α-synuclein-induced toxicity and PD pathogenesis, thus identifying TFEB as a promising target for therapies aimed at neuroprotection and disease modification in PD.
| S-EPMC3651458 | biostudies-literature
Project description:The neuropathological substrate of dementia with Lewy bodies (DLB) is defined by the inextricable cross-seeding accretion of amyloid-β (Aβ) and α-synuclein (α-syn)-laden deposits in cholinergic neurons. The recent revelation that neuropeptide kisspeptin-10 (KP-10) is able to mitigate Aβ toxicity via an extracellular binding mechanism may provide a new horizon for innovative drug design endeavors. Considering the sequence similarities between α-syn's non-amyloid-β component (NAC) and Aβ's C-terminus, we hypothesized that KP-10 would enhance cholinergic neuronal resistance against α-syn's deleterious consequences through preferential binding. Here, human cholinergic SH-SY5Y cells were transiently transformed to upsurge the mRNA expression of α-syn while α-syn-mediated cholinergic toxicity was quantified utilizing a standardized viability-based assay. Remarkably, the E46K mutant α-syn displayed elevated α-syn mRNA levels, which subsequently induced more cellular toxicity compared with the wild-type α-syn in choline acetyltransferase (ChAT)-positive cholinergic neurons. Treatment with a high concentration of KP-10 (10 µM) further decreased cholinergic cell viability, while low concentrations of KP-10 (0.01-1 µM) substantially suppressed wild-type and E46K mutant α-syn-mediated toxicity. Correlating with the in vitro observations are approximations from in silico algorithms, which inferred that KP-10 binds favorably to the C-terminal residues of wild-type and E46K mutant α-syn with CDOCKER energy scores of -118.049 kcal/mol and -114.869 kcal/mol, respectively. Over the course of 50 ns simulation time, explicit-solvent molecular dynamics conjointly revealed that the docked complexes were relatively stable despite small-scale fluctuations upon assembly. Taken together, our findings insinuate that KP-10 may serve as a novel therapeutic scaffold with far-reaching implications for the conceptualization of α-syn-based treatments.
| S-EPMC9105316 | biostudies-literature
Project description:?-Synuclein (SNCA) is a presynaptic protein that is associated with the pathophysiology of synucleinopathies, including Parkinson's disease. SNCA is a naturally aggregation-prone protein, which may be degraded by the ubiquitin-proteasome system (UPS) and by lysosomal degradation pathways. Besides being a target of the proteolytic systems, SNCA can also alter the function of these pathways further, contributing to the progression of neurodegeneration. Deterioration of UPS and autophagy activities with aging further aggravates this toxic cycle. Caloric restriction (CR) is still the most effective non-genetic intervention promoting lifespan extension. It is known that CR-mediated lifespan extension is linked to the regulation of proteolytic systems, but the mechanisms underlying CR rescue of SNCA toxicity remain poorly understood. This study shows that CR balances UPS and autophagy activities during aging. CR enhances UPS activity, reversing the decline of the UPS activity promoted by SNCA, and keeps autophagy at homeostatic levels. Maintenance of autophagy at homeostatic levels appears to be relevant for UPS activity and for the mechanism underlying rescue of cells from SNCA-mediated toxicity by CR.
| S-EPMC6326672 | biostudies-other
Project description:Parkinson´s disease (PD) pathology progresses throughout the nervous system. Whereas motor symptoms are always present, there is a high variability in the prevalence of non-motor symptoms. It has been postulated that the progression of the pathology is based on a prion-like disease mechanism partly due to the seeding effect of endocytosed-alpha-synuclein (ASYN) on the endogenous ASYN. Here, we analyzed the role of endogenous ASYN in the progression of PD-like pathology in vivo and in vitro and compared the effect of endocytosed-ASYN as well as paraquat and rotenone on primary enteric, dopaminergic and cortical neurons from wild-type and ASYN-KO mice. Our results show that, in vivo, pathology progression did not occur in the absence of endogenous ASYN. Remarkably, the damage caused by endocytosed-ASYN, rotenone or paraquat was independent from endogenous ASYN and related to the alteration of the host´s mitochondrial membrane potential. Dopaminergic neurons were very sensitive to these noxae compared to other neuronal subtypes. These results suggest that ASYN-mitochondrial interactions play a major role in initiating the pathological process in the host neuron and endogenous ASYN is essential for the transsynaptical transmission of the pathology. Our results also suggest that protecting mitochondrial function is a valid primary therapeutic target.
| S-EPMC9763379 | biostudies-literature
Project description:BackgroundSynucleinopathies are characterized by neurodegeneration and deposition of the presynaptic protein α-synuclein in pathological protein inclusions. Growing evidence suggests the complement system not only has physiological functions in the central nervous system, but also is involved in mediating the pathological loss of synapses in Alzheimer's disease. However, it is not established whether the complement system has a similar role in the diseases Parkinson's disease, Dementia with Lewy bodies, and multiple system atrophy (MSA) that are associated with α-synuclein aggregate pathology.MethodsTo investigate if the complement system has a pathological role in synucleinopathies, we assessed the effect of the complement system on the viability of an α-synuclein expressing cell model and examined direct activation of the complement system by α-synuclein in a plate-based activation assay. Finally, we investigated the levels of the initiator of the classical pathway, C1q, in postmortem brain samples from MSA patients.ResultsWe demonstrate that α-synuclein activates the classical complement pathway and mediates complement-dependent toxicity in α-synuclein expressing SH-SY5Y cells. The α-synuclein-dependent cellular toxicity was rescued by the complement inhibitors RaCI (inhibiting C5) and Cp20 (inhibiting C3). Furthermore, we observed a trend for higher levels of C1q in the putamen of MSA subjects than that of controls.Conclusionα-Synuclein can activate the classical complement pathway, and the complement system is involved in α-synuclein-dependent cellular cytotoxicity suggesting the system could play a prodegenerative role in synucleinopathies.
| S-EPMC8369722 | biostudies-literature
Project description:Neurodegeneration in Parkinson's disease (PD) can be recapitulated in animals by administration of α-synuclein preformed fibrils (PFFs) into the brain. However, the mechanism by which these PFFs induce toxicity is unknown. Iron is implicated in PD pathophysiology, so we investigated whether α-synuclein PFFs induce ferroptosis, an iron-dependent cell death pathway. A range of ferroptosis inhibitors were added to a striatal neuron-derived cell line (STHdhQ7/7 cells), a dopaminergic neuron-derived cell line (SN4741 cells), and WT primary cortical neurons, all of which had been intoxicated with α-synuclein PFFs. Viability was not recovered by these inhibitors except for liproxstatin-1, a best-in-class ferroptosis inhibitor, when used at high doses. High-dose liproxstatin-1 visibly enlarged the area of a cell that contained acidic vesicles and elevated the expression of several proteins associated with the autophagy-lysosomal pathway similarly to the known lysosomal inhibitors, chloroquine and bafilomycin A1. Consistent with high-dose liproxstatin-1 protecting via a lysosomal mechanism, we further de-monstrated that loss of viability induced by α-synuclein PFFs was attenuated by chloroquine and bafilomycin A1 as well as the lysosomal cysteine protease inhibitors, leupeptin, E-64D, and Ca-074-Me, but not other autophagy or lysosomal enzyme inhibitors. We confirmed using immunofluorescence microscopy that heparin prevented uptake of α-synuclein PFFs into cells but that chloroquine did not stop α-synuclein uptake into lysosomes despite impairing lysosomal function and inhibiting α-synuclein toxicity. Together, these data suggested that α-synuclein PFFs are toxic in functional lysosomes in vitro. Therapeutic strategies that prevent α-synuclein fibril uptake into lysosomes may be of benefit in PD.
| S-EPMC7762966 | biostudies-literature
Project description:Pathogenic α-synuclein and tau are critical drivers of neurodegeneration, and their mutations cause neuronal loss in patients. Whether the underlying preferential neuronal vulnerability is a cell-type-intrinsic property or a consequence of increased expression levels remains elusive. Here, we explore cell-type-specific α-synuclein and tau expression in human brain datasets and use deep phenotyping as well as brain-wide single-cell RNA sequencing of >200 live neuron types in fruit flies to determine which cellular environments react most to α-synuclein or tau toxicity. We detect phenotypic and transcriptomic evidence of differential neuronal vulnerability independent of α-synuclein or tau expression levels. Comparing vulnerable with resilient neurons in Drosophila enabled us to predict numerous human neuron subtypes with increased intrinsic susceptibility to pathogenic α-synuclein or tau. By uncovering synapse- and Ca2+ homeostasis-related genes as tau toxicity modifiers, our work paves the way to leverage neuronal identity to uncover modifiers of neurodegeneration-associated toxic proteins.
| S-EPMC10191620 | biostudies-literature
Project description:Mutations and copy number variation in the SNCA gene encoding the neuronal protein alpha-synuclein have been linked to familial Parkinson disease (Thomas, B., and Beal, M. F. (2007) Parkinson's disease. Hum. Mol. Genet. 16, R183-R194). The carboxyl terminus of alpha-synuclein can be phosphorylated at tyrosine 125 and serine 129, although only a small fraction of the protein is phosphorylated under normal conditions (Okochi, M., Walter, J., Koyama, A., Nakajo, S., Baba, M., Iwatsubo, T., Meijer, L., Kahle, P. J., and Haass, C. (2000) Constitutive phosphorylation of the Parkinson's disease associated alpha-synuclein. J. Biol. Chem. 275, 390-397). Under pathological conditions, such as in Parkinson disease, alpha-synuclein is a major component of Lewy bodies, a pathological hallmark of Parkinson disease, and is mostly phosphorylated at Ser-129 (Anderson, J. P., Walker, D. E., Goldstein, J. M., de Laat, R., Banducci, K., Caccavello, R. J., Barbour, R., Huang, J. P., Kling, K., Lee, M., Diep, L., Keim, P. S., Shen, X. F., Chataway, T., Schlossmacher, M. G., Seubert, P., Schenk, D., Sinha, S., Gai, W. P., and Chilcote, T. J. (2006) Phosphorylation of Ser-129 is the dominant pathological modification of alpha-synuclein in familial and sporadic Lewy body disease. J. Biol. Chem. 281, 29739-29752). Controversy exists over the extent to which phosphorylation of alpha-synuclein and/or the visible protein aggregation in Lewy bodies are steps in disease pathogenesis, are protective, or are neutral markers for the disease process. Here we used the combination of peptide pulldown assays and mass spectrometry to identify and compare protein-protein interactions of phosphorylated and non-phosphorylated alpha-synuclein. We showed that non-phosphorylated alpha-synuclein carboxyl terminus pulled down protein complexes that were highly enriched for mitochondrial electron transport proteins, whereas alpha-synuclein carboxyl terminus phosphorylated on either Ser-129 or Tyr-125 did not. Instead the set of proteins pulled down by phosphorylated alpha-synuclein was highly enriched in certain cytoskeletal proteins, in vesicular trafficking proteins, and in a small number of enzymes involved in protein serine phosphorylation. This targeted comparative proteomics approach for unbiased identification of protein-protein interactions suggests that there are functional consequences when alpha-synuclein is phosphorylated.
| S-EPMC2577212 | biostudies-literature
Project description:The abnormal accumulation of alpha-synuclein (α-syn) aggregates in neurons and glial cells is widely known to be associated with many neurodegenerative diseases, including Parkinson's disease (PD), Dementia with Lewy bodies (DLB), and Multiple system atrophy (MSA). Mitochondrial dysfunction in neurons and glia is known as a key feature of α-syn toxicity. Studies aimed at understanding α-syn-induced toxicity and its role in neurodegenerative diseases have primarily focused on neurons. However, a growing body of evidence demonstrates that glial cells such as microglia and astrocytes have been implicated in the initial pathogenesis and the progression of α-Synucleinopathy. Glial cells are important for supporting neuronal survival, synaptic functions, and local immunity. Furthermore, recent studies highlight the role of mitochondrial metabolism in the normal function of glial cells. In this work, we review the complex relationship between glial mitochondria and α-syn-mediated neurodegeneration, which may provide novel insights into the roles of glial cells in α-syn-associated neurodegenerative diseases.
| S-EPMC7686475 | biostudies-literature
Project description:The mechanism by which the Parkinson's disease-related protein alpha-synuclein (alpha-syn) causes neurodegeneration has not been elucidated. To determine the genes that protect cells from alpha-syn, we used a genetic screen to identify suppressors of the super sensitivity of the yeast Saccharomyces cerevisiae expressing alpha-syn to killing by hydrogen peroxide. Forty genes in ubiquitin-dependent protein catabolism, protein biosynthesis, vesicle trafficking and the response to stress were identified. Five of the forty genes--ENT3, IDP3, JEM1, ARG2 and HSP82--ranked highest in their ability to block alpha-syn-induced reactive oxygen species accumulation, and these five genes were characterized in more detail. The deletion of any of these five genes enhanced the toxicity of alpha-syn as judged by growth defects compared with wild-type cells expressing alpha-syn, which indicates that these genes protect cells from alpha-syn. Strikingly, four of the five genes are specific for alpha-syn in that they fail to protect cells from the toxicity of the two inherited mutants A30P or A53T. This finding suggests that alpha-syn causes toxicity to cells through a different pathway than these two inherited mutants. Lastly, overexpression of Ent3p, which is a clathrin adapter protein involved in protein transport between the Golgi and the vacuole, causes alpha-syn to redistribute from the plasma membrane into cytoplasmic vesicular structures. Our interpretation is that Ent3p mediates the transport of alpha-syn to the vacuole for proteolytic degradation. A similar clathrin adaptor protein, epsinR, exists in humans.
| S-EPMC2581432 | biostudies-literature