Section Days abstract book 2010.indd - RUB Research School ...

LS_11
Expression of accessory proteins of glutamate receptors
during neural differentiation of embryonic stem cells
Steffen Pahl, Elke Muth-Köhne, Svenja Pachernegg, Michael Hollmann
Department of Biochemistry I, Faculty of Chemistry and Biochemistry, Ruhr University
Bochum, 44780 Bochum, Germany
International Graduate School of Neuroscience, Ruhr University Bochum, 44780 Bochum,
Germany
e-mail: Steffen.Pahl@rub.de
Ionotropic glutamate receptors mediate excitatory neurotransmission in the adult vertebrate
CNS. Recent studies gave reason to expect iGluRs to be involved in the process of neural
differentiation of embryonic stem cells. Since there is evidence that a group of proteins,
namely TARPs, alter electrophysiological properties and trafficking of AMPARs, interaction
of accessory proteins with iGluRs could also influence neural differentiation. Following the
neuronal differentiation of ESCs an increase in mRNA expression levels of accessory proteins
correlating to an increase in expression of iGluRs was observed. Furthermore, protein
expression, except for PSD-95, was first detectable after differentiation of the cells into early
neurons. PSD-95 protein expression instead was already detected in the stage of NEPs.
A second part of the work focused on the electrophysiological characterization of an NMDAR
composed of the subunits NR1-1a and NR2A coexpressed with the putative NMDAR
accessory protein NETO1. The results showed that coexpression of NETO1 alone had no
effect on the agonist-induced currents of the analyzed NMDAR. However a combined
coexpression of NETO1 and total RNA isolated from adult mouse whole brain resulted in
increased agonist-induced currents, a lowered ion conductance at negative membrane
potentials and an inhibition of the block by MK801 on the analyzed NMDAR. These results
lead to the assumption that an additional protein is needed for modulation of NMDARs by
NETO1.