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Single particle investigation of membrane binding properties and Ca2+ conductivity of Fe3+-induced α-synuclein oligomers
Basal Ganglia 3 (2013) 39–71
Contents lists available at SciVerse ScienceDirect
Basal Ganglia journal homepage: www.elsevier.com/locate/baga
Abstracts German Parkinson Congress, Würzburg, 13–15 March 2013
Poster session: Genetics and Molecular Pathophysiology
P2
P1
G. Nübling, F. Schmidt, F. Kamp, T. Högen, L. Johannes, S. Lorenzl, A. Giese
Characterization of sphingosine-1-phosphate and its receptors in Parkinson’s disease – Is there a link? J.C.M. Schlachetzki, J. von Wittgenstein, B. Winner, I. Prots, J. Winkler Erlangen, Germany Inflammation in Parkinson’s disease (PD) has been recently recognized not only as a mere bystander during disease progression but in particular as an important disease modifying or even accelerating factor. Recently, several genes involved in PD have been suggested to impinge on the sphingolipid metabolism (Bras et al., 2008). However, the role of the sphingolipid sphingosine 1-phosphate (S1P) and its receptors (S1P1–S1P5) is much less understood in PD. S1P influences cell proliferation and activation via binding to the G-protein coupled S1P receptors in astrocytes. In addition, the receptor S1P1 is involved in the activation and migration of microglial cells (Y. Wei et al., 2010). Modulation of S1P receptors has been shown to be efficious in neuroinflammatory diseases such as multiple sclerosis (V. Brinkmann et al., 2010) and exerts neuroprotective effects in acute ischemia (Y. Wei et al., 2010). We hypothesize that S1P receptors are promising targets for disease modifying approaches in PD due to its diverse actions on neurons and microglia. Here we studied, whether modulation of S1P and its receptors (1) confer neuroprotection in a human mesencephalic cell line with a dopaminergic phenotype, and (2) regulates neuroinflammatory processes in a microglial cell line. In addition, we conducted a detailed analysis of monocytes derived from 14 male PD patients and healthy age- and sex-matched controls with respect to the gene expression of all five S1P receptors and S1P-dependent pathways. In future experiments, we aim to test a possible disease-modifying effect of S1P1 in acute and transgenic models of PD. http://dx.doi.org/10.1016/j.baga.2013.01.002
2210-5336/$ – see front matter http://dx.doi.org/10.1016/j.baga.2013.01.001
Single particle investigation of membrane binding properties and Ca2+ conductivity of Fe3+ -induced ␣-synuclein oligomers
München, Germany Background: Synucleinopathies are a heterogeneous group of neurodegenerative disorders characterized by intracellular deposits of aggregated ␣-synuclein (asyn). It is increasingly recognized that small asyn oligomers might be the pathophysiologically relevant toxic aggregate species in these diseases. Furthermore, several lines of evidence point towards a potential role of trivalent metal ions in asyn oligomer formation. Recent evidence indicates that asyn oligomers may act as membrane pores interfering with the electrophysiological equilibrium of neuronal membranes. Methods: We applied fluorimetry, single particle fluorescence techniques and a setup for single-channel electrophysiology montioring of membrane conductance to investigate a possible role of Fe3+ induced asyn oligomers as Ca2+ conducting membrane pores. We further investigated the influence of asyn S129E pseudophosphorylation on oligomer binding to small unilammelar vesicles (SUV). Results: We demonstrate that asyn binding to lipid membranes is strongly dependent on both aggregation state and membrane composition. Fe3+ -induced asyn oligomers bind to lipid vesicles and planar bilayers and increase transmembranous Ca2+ conductance. Pseudophosphorylation at position 129 inhibits binding of Fe3+ induced oligomers to SUV. Discussion: Our results corroborate the previous finding that Fe3+ -induced asyn oligomers may act as membrane pores. These oligomers exhibit Ca2+ conductivity and may thus exert neurotoxicity. Phosphorylation at position 129 inhibits oligomer membrane binding and may thus play a neuroprotective role. http://dx.doi.org/10.1016/j.baga.2013.01.003
Contents lists available at SciVerse ScienceDirect
Basal Ganglia journal homepage: www.elsevier.com/locate/baga
Abstracts German Parkinson Congress, Würzburg, 13–15 March 2013
Poster session: Genetics and Molecular Pathophysiology
P2
P1
G. Nübling, F. Schmidt, F. Kamp, T. Högen, L. Johannes, S. Lorenzl, A. Giese
Characterization of sphingosine-1-phosphate and its receptors in Parkinson’s disease – Is there a link? J.C.M. Schlachetzki, J. von Wittgenstein, B. Winner, I. Prots, J. Winkler Erlangen, Germany Inflammation in Parkinson’s disease (PD) has been recently recognized not only as a mere bystander during disease progression but in particular as an important disease modifying or even accelerating factor. Recently, several genes involved in PD have been suggested to impinge on the sphingolipid metabolism (Bras et al., 2008). However, the role of the sphingolipid sphingosine 1-phosphate (S1P) and its receptors (S1P1–S1P5) is much less understood in PD. S1P influences cell proliferation and activation via binding to the G-protein coupled S1P receptors in astrocytes. In addition, the receptor S1P1 is involved in the activation and migration of microglial cells (Y. Wei et al., 2010). Modulation of S1P receptors has been shown to be efficious in neuroinflammatory diseases such as multiple sclerosis (V. Brinkmann et al., 2010) and exerts neuroprotective effects in acute ischemia (Y. Wei et al., 2010). We hypothesize that S1P receptors are promising targets for disease modifying approaches in PD due to its diverse actions on neurons and microglia. Here we studied, whether modulation of S1P and its receptors (1) confer neuroprotection in a human mesencephalic cell line with a dopaminergic phenotype, and (2) regulates neuroinflammatory processes in a microglial cell line. In addition, we conducted a detailed analysis of monocytes derived from 14 male PD patients and healthy age- and sex-matched controls with respect to the gene expression of all five S1P receptors and S1P-dependent pathways. In future experiments, we aim to test a possible disease-modifying effect of S1P1 in acute and transgenic models of PD. http://dx.doi.org/10.1016/j.baga.2013.01.002
2210-5336/$ – see front matter http://dx.doi.org/10.1016/j.baga.2013.01.001
Single particle investigation of membrane binding properties and Ca2+ conductivity of Fe3+ -induced ␣-synuclein oligomers
München, Germany Background: Synucleinopathies are a heterogeneous group of neurodegenerative disorders characterized by intracellular deposits of aggregated ␣-synuclein (asyn). It is increasingly recognized that small asyn oligomers might be the pathophysiologically relevant toxic aggregate species in these diseases. Furthermore, several lines of evidence point towards a potential role of trivalent metal ions in asyn oligomer formation. Recent evidence indicates that asyn oligomers may act as membrane pores interfering with the electrophysiological equilibrium of neuronal membranes. Methods: We applied fluorimetry, single particle fluorescence techniques and a setup for single-channel electrophysiology montioring of membrane conductance to investigate a possible role of Fe3+ induced asyn oligomers as Ca2+ conducting membrane pores. We further investigated the influence of asyn S129E pseudophosphorylation on oligomer binding to small unilammelar vesicles (SUV). Results: We demonstrate that asyn binding to lipid membranes is strongly dependent on both aggregation state and membrane composition. Fe3+ -induced asyn oligomers bind to lipid vesicles and planar bilayers and increase transmembranous Ca2+ conductance. Pseudophosphorylation at position 129 inhibits binding of Fe3+ induced oligomers to SUV. Discussion: Our results corroborate the previous finding that Fe3+ -induced asyn oligomers may act as membrane pores. These oligomers exhibit Ca2+ conductivity and may thus exert neurotoxicity. Phosphorylation at position 129 inhibits oligomer membrane binding and may thus play a neuroprotective role. http://dx.doi.org/10.1016/j.baga.2013.01.003