Project description:We performed RNAseq using whole Drosophila heads after expressing human wild type alpha synuclein in either glia, neurons, or both types. We identified many upregulated genes when alpha synuclein was expresed in glia and many downregulated genes with it was expresed in neurons or both cell types.
Project description:Abnormal neuronal aggregation of a-synuclein is implicated in the development of Parkinson’s disease. Glial cells also show extensive a-synuclein pathology and are thought to contribute to disease progression. However, the mechanism that produces the glial a-synuclein pathology and the interaction between neurons and glia in the disease-inflicted microenvironment remain unknown. Here, we show that in neuronal cells misfolded a-synuclein proteins are selectively translocated into vesicles, leading to exocytosis of the aggregated forms. More importantly, our data demonstrate that astrocytes take up the neuron-derived a-synuclein aggregates and produce a-synuclein inclusions similar to the ones found in human brains. This uptake is paralleled by changes in the gene expression profile reflecting an inflammatory response. These results suggest that astroglial a-synuclein pathology is produced by cell-to-cell transmission of neuronal a-synuclein aggregates. This transmission step is thus an important mediator of pathogenic glial responses and could qualify as a new therapeutic target. To determine how astrocytes respond to extracellular a-synuclein, gene expression profiles were established and analyzed for nearly 22,000 rat genes using the Illumina RatRef-12 Expression BeadChip. Total RNA was isolated from astrocytes exposed for 6h or 24h to conditioned medium from cultures of a-synuclein or lacZ expressing cells.
Project description:Abnormal neuronal aggregation of a-synuclein is implicated in the development of Parkinson’s disease. Glial cells also show extensive a-synuclein pathology and are thought to contribute to disease progression. However, the mechanism that produces the glial a-synuclein pathology and the interaction between neurons and glia in the disease-inflicted microenvironment remain unknown. Here, we show that in neuronal cells misfolded a-synuclein proteins are selectively translocated into vesicles, leading to exocytosis of the aggregated forms. More importantly, our data demonstrate that astrocytes take up the neuron-derived a-synuclein aggregates and produce a-synuclein inclusions similar to the ones found in human brains. This uptake is paralleled by changes in the gene expression profile reflecting an inflammatory response. These results suggest that astroglial a-synuclein pathology is produced by cell-to-cell transmission of neuronal a-synuclein aggregates. This transmission step is thus an important mediator of pathogenic glial responses and could qualify as a new therapeutic target.
Project description:α-Synuclein is an abundant presynaptic protein that when aggregated and dyslocated from the synapse is associated to Parkinson’s disease and dementia. The normal presynaptic function of α-synuclein is unclear as well as the disease triggering mechanism. In order to extend the knowledge of the α-synuclein interactome during normal function and disease, we have used porcine brain synaptosomes as a source of ligands and purified α-synuclein monomers or oligomers as bait in co-immunoprecipitation experiments. The isolated binding synaptosomal proteins were identified with LC-LTQ-orbitrap tandem mass spectrometry and quantified by peak area using the freely-available Windows client application, Skyline Targeted Proteomic Environment. To compare proteins binding to a-synuclein monomer with proteins binding to a-synuclein oligomer, quantifications were log transformed, normalized to buffer-background, and compared by students t-test. Furthermore, to specify the preferential binding an average fold increase was calculated by comparing binding to monomer and oligomer. 10 α-synuclein preferential monomer binding proteins were identified and among those, we successfully validated Abl interactor 1, and myelin proteolipid protein. 76 α-synuclein preferential oligomer binding proteins were found, including glutamate decarboxylase 2, synapsin 1, and glial fibrillary acidic protein, which were positively validated. We identified 92 proteins binding to α-synuclein, for which we were not able to detect any conformational preferences among. This study presents a catalog of proteins interacting with α-synuclein in its non-aggregated and aggregated oligomeric state, which can be used to investigate the normal and pathological roles of α-synuclein.
Project description:Alpha-synuclein is an abundant protein implicated in synaptic function and plasticity, but the molecular mechanism of its action is not understood. Missense mutations and gene duplication/triplication events result in Parkinson's disease, a neurodegenerative disorder of old age with impaired movement and emotion control. Here, we systematically investigated the striatal as well as the cerebellar transcriptome profile of alpha-synuclein-deficient mice via a genome-wide microarray survey in order to gain hypothesis-free molecular insights into the physiological function of alpha-synuclein. A genotype-dependent, specific and strong downregulation of forkhead box P1 (Foxp1) transcript levels was observed in all brain regions from postnatal age until old age and could be validated by qPCR. In view of the co-localization and heterodimer formation of FOXP1 with FOXP2, a transcription factor with a well established role for vocalization, and the reported regulation of both alpha-synuclein and FOXP2 expression during avian song learning, we performed a detailed assessment of mouse movements and vocalizations in the postnatal period. While there was no difference in isolation-induced behavioral activity in these animals, the alpha-synuclein-deficient mice exhibited an increased production of isolation-induced ultrasonic vocalizations (USVs). This phenotype might also reflect the reduced expression of the anxiety-related GABA-A receptor subunit gamma 2 (Gabrg2) we observed. Taken together, we identified an early behavioral consequence of alpha-synuclein deficiency and accompanying molecular changes, which supports the notion that the neural connectivity of sound or emotion control systems is affected. Factorial design comparing SNCA knock-out mice with wild type littermates in two different tissues (striatum, cerebellum) at two different timepoints (6 and 21 month)
Project description:We conducted a screening for nuclear proteins which interact with α-synuclein by mass-spectrometry. As a result, we found that α-synuclein interact with BAF complex. Furthermore, overexpressed α-synuclein increased global H4R3me2s by promoting interaction between BAF complex and PRMT5 in cultered cells. In this study, we explored the influence of overexpressed α-synuclein on H4R3me2s by ChIP-seq using anti-H4R3me2s antibody.
Project description:Abnormal accumulation of aggregated proteins and sustained microglial activation are important contributors of neurodegenerative process in neurological diseases. Recent studies have shown that aggregation-prone proteins, such as a-synuclein, the protein implicated in Parkinson’s disease (PD), are released from neuronal cells and thus present in the extracellular fluid, pointing to the possible paracrine effects of these proteins on microglial immune responses. However, the mechanism underlying the disease-associated microglial activation and the role of neuronal proteins in this process remain unknown. Here, we show that extracellular a-synuclein released from neuronal cells is an endogenous ligand of toll-like receptor 2 (TLR2) and activates microglia, which in turn induces neurodegeneration. Interaction between neuron-released a-synuclein and TLR2 and subsequent activation of the TLR2 signaling were demonstrated comprehensively by using computational modeling of signaling network and by the experimental validation in TLR2-deficient microglia both in vitro and in vivo. In contrast to the neuron-released a-synuclein, recombinant a-synuclein proteins, including monomer, oligomer, fibril, or nitrated forms, were not able to interact or activate TLR2, suggesting that neuronal cells have a mechanism of enriching specific forms of a-synuclein capable of activating TLR2 during the process of releasing this protein. Taken together, the results suggest that both neuron-released extracellular a-synuclein and TLR2 might be novel therapeutic targets for modifying neuroinflammation in PD and related neurodegenerative diseases. We collected culture media from differentiated SH-SY5Y cells overexpressing either human a-synuclein (alpha-SCM) or beta-galactosidase (LZCM) and treat these media to primary rat microglia at the concentration of a-synuclein of 1.1M. Transcriptome analyses with microglial cells treated with either aSCM or LZCM at two different time points, 6 h and 24 h.
Project description:Alpha synuclein in it's native state in solution was crosslinked using a variety of short-range crosslinking reagents. Crosslinks detected by mass spectrometry were then used as constraints in a discrete molecular dynamics simulation of the synuclein protein, and a structural ensemble of the protein was determined.
Project description:A key process of neurodegeneration in Parkinson's disease (PD) is the transneuronal spreading of alpha-synuclein. Alpha-synuclein is a presynaptic protein that is implicated in the pathogenesis of PD and other synucleinopathies, where it forms, upon intracellular aggregation, pathological inclusions. Other hallmarks of PD include neurodegeneration and microgliosis in susceptible brain regions. Whether it is primarily transneuronal spreading of a-synuclein particles, inclusion formation, or other mechanisms, such as inflammation, that cause neurodegeneration in PD is unclear. We used spreading/aggregation of alpha-synuclein induced by intracerebral injection of a-synuclein preformed fibrils into the mouse brain to address this question. We performed quantitative histological analysis for a-synuclein inclusions, neurodegeneration, and microgliosis in different brain regions, and a gene expression profiling of the ventral midbrain, at two different timepoints after disease induction. We observed significant neurodegeneration and microgliosis in brain regions not only with, but also withouta-synuclein inclusions. We also observed prominent microgliosis in injured brain regions that did not correlate with neurodegeneration nor with inclusion load. In longitudinal gene expression profiling experiments, we observed early and unique alterations linked to microglial mediated inflammation that preceded neurodegeneration, indicating an active role of microglia in inducing neurodegeneration. Our observations indicate that a-synuclein inclusion formation is not the major driver in the early phases of PD-like neurodegeneration, but that diffusible, oligomeric a-synuclein species, which induce unusual microglial reactivity, play a key role in this process.
Project description:Altogether results show that peroxidase activity of cytochrome c contributes to α-synuclein radical formation and oligomerization, and that α-synuclein through its co-localization with cytochrome c or on it's own, affects several biological pathways which contribute to increased neuronal death in Maneb and paraquat (MP)-induced model of Parkinson's disease.