EURON and THEME joint PhD meeting

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82 EURON and THEME joint meeting 2011 Does the proteoglycan NG2 influence neuron-NG2 cell synaptic signaling? S. Passlick 1 , K. Karram 2,3 , J. Trotter 3 , G. Seifert 1 , C. Steinhäuser 1 , R. Jabs 1 1 Institute of Cellular Neurosciences, University of Bonn, Germany; 2 Institute for Molecular Medicine, University of Mainz, Germany; 3 Molecular Cell Biology, University of Mainz, Germany. Glial cells expressing the proteoglycan NG2 are widely distributed throughout the developing and adult gray and white matter of the CNS. Several properties distinguish them from astrocytes, mature oligodendrocytes and microglia. NG2 cells express different types of voltage-gated K + , Na + , and Ca 2+ -channels. They also express a variety of ligand-gated receptors including group I metabotropic glutamate receptors and ionotropic AMPA- and GABA A -receptors. Furthermore, NG2 cells are the only non-neuronal cells in the CNS that form synapses with neurons. In this respect, it is interesting that the NG2 protein (i) binds to the postsynaptic Glutamate Receptor Interaction Protein (GRIP) and (ii) contains two Laminin G/Neurexin/Sex Hormone Binding Globulin (LNS) domains in the extracellular region. GRIP is considered important for clustering of the GluR2 subunit of AMPA receptors. LNS domains are characteristic for postsynaptic neurexins that, by binding to presynaptic neuroligins, are important for synapse formation in neurons. In this study we asked whether the NG2 protein is crucial for the formation of functional NG2 cell synapses, by influencing clustering of postsynaptic receptors or neuroligin interactions. To address this issue, we investigated synaptic transmission between glutamatergic neurons and NG2 cells in NG2-EYFP-knockin (+/- and -/-) and wildtype mice (p 8-14). We recorded whole-cell membrane currents from hippocampal NG2 cells during electrical stimulation of Schaffer collaterals and analysed the evoked excitatory postsynaptic currents (eEPSCs). Comparison of the kinetics and paired-pulse ratios of NG2 cell eEPSCs revealed no significant differences among the tested genotypes. We conclude that the lack of the NG2 protein does not cause a general failure of synaptic signaling between glutamatergic neurons and NG2 cells in the hippocampus. It remains to be tested whether miniature EPSCs, which are not synchronised by presynaptic action potentials, are affected in NG2-deficient mice. Supported by DFG (SPP 1172) and EC (FP7-202167 Neuroglia).
83 EURON and THEME joint meeting 2011 Multiple Mitochondrial DNA deletions in human disease Viktoriya Peeva, Gábor Zsurka, Susanne Schöler, Alexei P. Kudin, Stefan Vielhaber, Grazyna Debska-Vielhaber, Werner Zuschratter, Cornelia Kornblum, and Wolfram S. Kunz Division of Neurochemistry, Department of Epileptology and Life&Brain Center, University Bonn, Sigmund-Freud-Str. 25, 53105, Bonn, Germany. Charcot-Marie-Tooth neuropathy type 2A (CMT2A) is an autosomal dominant axonal form of peripheral neuropathy caused by mutations in the mitofusin 2 gene (MFN2), which encodes a mitochondrial outer membrane protein that promotes mitochondrial fusion. In this study we investigated two novel MFN2 mutations and their effect on mitochondrial function in skeletal muscle and cultured fibroblasts of two patients affected by the disease. To elucidate the potential mitochondrial impairment in skeletal muscle biopsies and fibroblasts of these patients, high-resolution respirometry and sensitive PCRbased deletion detection methods were applied, and the mtDNA copy number was determined. Altered distribution of mitochondria in type 2A skeletal muscle fibers, characterized with accumulation of subsarcolemmal mitochondria and rarefication of intermyofibrillar mitochondria were observed in skeletal muscle biopsy from the patients. The sensitivity of saponin-permeabilized muscle fibers and digitoninpermeabilized fibroblasts to the cytochrome c oxidase (COX) inhibitor azide increased, although their maximal activities of respiration were only slightly affected by the MFN2 mutations. In comparison to controls, the MFN2 muscle showed decrease in the mtDNA copy number (the extent of mtDNA depletion was lower when compared to patients carrying POLG mutation), and elevated levels of mtDNA deletions. Overall, these mtDNA changes are implicated to cause the increased flux control of COX in CMT2A fibroblasts and skeletal muscle. Our findings support the viewpoint that impairment of the fusion proteins affect mitochondrial function. This appears to be related to the role of mitochondrial dynamics for segregation of mtDNA mutations.
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EURON and THEME joint PhD meeting U
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The local organizing committee: Pro
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Information about THEME 3 EURON and
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5 EURON and THEME joint meeting 201
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EURON a short introduction 7 EURON
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Programme 13 EURON and THEME joint
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Thursday September 22 nd 9:00 - 10:
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Friday September 23 rd 17 EURON and
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Poster presentations 19 EURON and T
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EURON Lecture Frank Kirchhoff ADDRE
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ABSTRACT 25 EURON and THEME joint m
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THEME Lecture Eckhard Mandelkow POS
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ABSTRACT 29 EURON and THEME joint m
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Page 105 and 106: List of Participants 103 EURON and
Page 107 and 108: Nuersailike Abuduwali University of
Page 109 and 110: Marianne Eisenhardt University of B
Page 111 and 112: Sabine Klein University of Bonn PhD
Page 113 and 114: Viktoriya Peeva University of Bonn
Page 115: Sylvie van der Kruijs Maastricht Un
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EURON and THEME joint PhD meeting

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