CDC42EP4, a perisynaptic scaffold protein in Bergmann glia, is required for glutamatergic tripartite synapse configuration

Publication date: Available online 9 January 2018 Source:Neurochemistry International Author(s): Natsumi Ageta-Ishihara, Kohtarou Konno, Maya Yamazaki, Manabu Abe, Kenji Sakimura, Masahiko Watanabe, Makoto Kinoshita Configuration of tripartite synapses, comprising the pre-, post-, and peri-synaptic components (axon terminal or bouton, dendritic spine, and astroglial terminal process), is a critical determinant of neurotransmitter kinetics and hence synaptic transmission. However, little is known about molecular basis for the regulation of tripartite synapse morphology. Previous studies showed that CDC42EP4, an effector protein of a cell morphogenesis regulator CDC42, is expressed exclusively in Bergmann glia in the cerebellar cortex, that it forms tight complex with the septin heterooligomer, and that it interacts indirectly with the glutamate transporter GLAST and MYH10/nonmuscle myosin ΙΙB. Scrutiny of Cdc42ep4 -/- mice had revealed that the CDC42EP4-septins-GLAST interaction facilitates glutamate clearance, while the role for CDC42EP4-septins-MYH10 interaction has remained unsolved. Here, we find anomalous configuration of the tripartite synapses comprising the parallel fiber boutons, dendritic spines of Purkinje cells, and Bergmann glial processes in Cdc42ep4 -/- mice. The complex anomalies include 1) recession of Bergmann glial membranes from the nearest active zones, and 2) extension of nonactive synaptic contact around active zone. In line with the recession...

Source: Neurochemistry International - January 10, 2018 Category: Neuroscience Source Type: research