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Foto: Henseler, Copyright: BMBF
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Serotonylation of neuronal proteins by transglutaminases – Novel mechanisms in neuronal plasticity
Dr. René Hummerich, Helene Schamber, Prof. (apl.) Dr. Patrick Schloss
In the central nervous system serotonin plays important roles as a neurotransmitter as well as during neuronal development and in synaptogenesis. Outside the central nervous system, serotonin is covalently transamidated to procoagulant proteins involved in blood clotting. This process is mediated by transglutaminases and named “serotonylation”. Serotonylated proteins then tightly bind to specific serotonin binding sites on fibrinogen and thrombospondin to form stable extracellular multivalent complexes needed for thrombus formation. We investigate whether transglutaminases can also covalently incorporate extracellular serotonin to neural proteins and whether this might affect extracellular protein expression. So far, our data reveal that recombinant transglutaminase specifically transamidates [³H]-serotonin to cell-surface proteins from C6 glioma cells and the extracellular matrix protein fibronectin. Serotonylation of [³H]-serotonin was inhibited by the transglutaminase inhibitor cystamine and unlabelled serotonin. Transglutaminase-mediated transamidation of unlabelled serotonin to C6 cells induced an aggregation of extracellular protein matrices adjacent to and between single cells. Transglutaminase also transamidated the autofluorescent serotonin analogue 5, 7 dihydroxytryptamine and monodansylcadaverine (MDC) into living C6 glioma cells. Electrophoretic separation of MDC-labelled C6 cells identified several distinct fluorescent proteins one of which was fibronectin.
Differentiation of embryonic stem cells to neurons: models to study long-term changes and synaptic plasticity on the cellular level (SFB636)
Dr. Thorsten Lau, Felix Heimann, Eva Krause, Verena Proissl. Helene Schamber, Annabelle Schlüter, Christoph Spieler, Prof. (apl.) Dr. Patrick Schloss
Cognitive processes such as memory formation and extinction are controlled by modulatory inputs from serotonergic, noradrenergic and dopaminergic neurons and many mental disorders such as depression, anxiety and addiction involve disturbances in these neurotransmitter systems. Pharmaco-therapeutically applied drugs exert their action either by elevating monoamine concentrations in the extracellular space by blocking neurotransmitter re-uptake or by antagonizing the action of monoamines at the respective receptors. Interestingly, many drugs of abuse act directly on monoaminergic neurons by inhibiting neurotransmitter transporters (cocaine) or triggering transmitter release (ecstasy, nicotine and ethanol). With respect to drug/target interactions pharmacological and biochemical studies have so far been performed on brain synaptosomes or cells expressing recombinant target proteins. Up to now, it was not possible to analyze the effects of these drugs on the cellular level, because monoaminergic neurons expressing the native target proteins were not available in cell culture.
The goal of our project is to analyze the molecular mechanisms of psychoactive drugs on their native target molecules imbedded in their natural surroundings, i.e. in intact monoaminergic neurons. Therefore we have established differentiation protocols to generate dopaminergic and serotonergic neurons from mouse embryonic stem cells.
Generation of neuronal cells from human peripheral blood mononuclear cells: analysis of the expression and function of mental disease-associated proteins (e.g. BDNF)
Dr. Sandra Horschitz, Prof. Dr. Andreas Meyer-Lindenberg, Prof. (apl.) Dr. Patrick Schloss
We have examined the potency of two methods for the neuronal differentiation of embryonic stem cells on the generation of neuronal cells from human blood cells. A mixture of mononuclear cells from peripheral blood cells expressing monocytic, hematopoietic, and mesenchymal cell surface markers were exposed to all-trans retinoic acid, epidermal growth factor, and basic fibroblast growth factor (method A), or epidermal growth factor, fibroblast growth factor 8b, sonic hedgehog and ascorbic acid (method B). Both methods led to the generation of neuronal cells as judged by changes in morphology and the expression of the neuronal markers microtubule-associated protein type 2, tau, and beta-tubulin III. Differentiation according to method B favoured the development of neurons also expressing the dopamine transporter.
Differentiation of blood stem cells to megacaryocytes and platelets: Analyse the influence of methylphenidate on DAT expression and function
Dr. Yvonne Grimmer, Dr. Sarah Hohmann, Prof. Dr. Dr. Tobias Banaschweski, Prof. (apl.) Dr. Patrick Schloss
- in work -
Differentiation of blood stem cells to megacaryocytes and platelets: Analyse the influence of SSRIs on SERT expression and function (GRK880)
Nina Schweinfurth, Dr. Florian Lederbogen, Prof. (apl.) Dr. Michael Deuschle, Prof. (apl.) Dr. Patrick Schloss
- in work -
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