TY  - GEN
UR  - https://archiv.ub.uni-heidelberg.de/volltextserver/16199/
Y1  - 2014///
CY  - Heidelberg, Germany
TI  - CKAMP44 interacts with AMPARs via different protein domains and modulates neuronal morphogenesis
N2  - The L-?-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) are glutamate-gated ion channels that are important for fast synaptic transmission and synaptic plasticity in the central nervous system. The AMPARs? gating properties are tightly regulated by receptor number, subunit composition, co-transcriptional as well as post-translational subunit modifications and by their interactions with auxiliary proteins. Recently, a novel endogenous auxiliary protein of AMPARs, CKAMP44, was identified. CKAMP44 modulates the gating kinetics of AMPARs, such as deactivation, desensitization and recovery from desensitization. However, the detailed molecular mechanisms for the CKAMP44/AMPAR interaction and CKAMP44
regulation of AMPAR gating remain to be resolved. This dissertation unravels different CKAMP44 domains involved in AMPAR interaction and modulation, and investigates new roles of CKAMP44 in neuronal morphogenesis of primary neurons.
In order to identify CKAMP44 protein domains that are essential for CKAMP44/AMPAR interaction, AMPAR-mediated current modulation, and CKAMP44 spine delivery, a series of CKAMP44 deletion mutants were generated, expressed in HEK293 cells, primary hippocampal neurons and in neonatal mouse brains, and analyzed by co-immunoprecipitation, immunostaining and electrophysiological recordings. Our results show that the extracellular CKAMP44 domain triggers the modulation of AMPARs? gating properties. The intracellular Cterminal domain of CKAMP44 is required for postsynaptic localization of CKAMP44, and the R/K domain is needed for the physical CKAMP44/AMPAR interaction as well as for the efficient spine targeting of CKAMP44. The requirement of the R/K domain in CKAMP44/AMPAR binding might explain why the recombinantly expressed CKAMP44 extracellular domain failed to modulate AMPAR activity.
In addition to the regulatory function of CKAMP44 on AMPAR-mediated currents, our bidirectional manipulation of CKAMP44 expression in primary hippocampal neurons of Ckamp44?/? and wild-type mice provided evidence that
neuronal morphogenesis is modulated by CKAMP44. Primary neurons derived from Ckamp44?/? mice exhibited increased dendritic arborization and spine volume, but decreased spine density when compared to CKAMP44 expressing neurons.
IV CKAMP44 overexpression in neurons leads to the opposite results. In addition, CKAMP44 overexpression induced irregular spine morphology and multiple synapses generated at single spines. Therefore, we suggest that, in addition to the modulation of the AMPAR gating, CKAMP44 can tune dendritic arborization and spine formation during neuron maturation.
ID  - heidok16199
AV  - public
A1  - Zhang, Ling
ER  -