title: TrkB (tropomyosin-related kinase B) controls the assembly and maintenance of GABAergic synapses in the cerebellar cortex.
abstract: Inhibitory interneurons play a critical role in coordinating the activity of neural circuits. To explore the mechanisms that direct the organization of inhibitory circuits, we analyzed the involvement of tropomyosin-related kinase B (TrkB) in the assembly and maintenance of GABAergic inhibitory synapses between Golgi and granule cells in the mouse cerebellar cortex. We show that TrkB acts directly within each cell-type to regulate synaptic differentiation. TrkB is required not only for assembly, but also maintenance of these synapses and acts, primarily, by regulating the localization of synaptic constituents. Postsynaptically, TrkB controls the localization of a scaffolding protein, gephyrin, but acts at a step subsequent to the localization of a cell adhesion molecule, Neuroligin-2. Importantly, TrkB is required for the localization of an Ig superfamily cell adhesion molecule, Contactin-1, in Golgi and granule cells and the absence of Contactin-1 also results in deficits in inhibitory synaptic development. Thus, our findings demonstrate that TrkB controls the assembly and maintenance of GABAergic synapses and suggest that TrkB functions, in part, through promoting synaptic adhesion.
authors.affiliation: Department of Physiology, University of California, San Francisco, San Francisco, California 94158, USA.
authors.forename: Albert I
authors.initials: AI
authors.lastname: Chen
authors.forename: Cindy N
authors.initials: CN
authors.lastname: Nguyen
authors.forename: David R
authors.initials: DR
authors.lastname: Copenhagen
authors.forename: Sylvia
authors.initials: S
authors.lastname: Badurek
authors.forename: Liliana
authors.initials: L
authors.lastname: Minichiello
authors.forename: Barbara
authors.initials: B
authors.lastname: Ranscht
authors.forename: Louis F
authors.initials: LF
authors.lastname: Reichardt
mesh_terms: D000818:Animals; D002448:Cell Adhesion / Q000235:genetics / Q000502:physiology; D002454:Cell Differentiation / Q000235:genetics / Q000502:physiology*; D002525:Cerebellar Cortex / Q000201:enzymology* / Q000254:growth & development*; D007395:Interneurons / Q000166:cytology / Q000201:enzymology; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D020813:Receptor, trkB / Q000502:physiology*; D013569:Synapses / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D009435:Synaptic Transmission / Q000235:genetics; D014335:Tropomyosin / Q000502:physiology; D005680:gamma-Aminobutyric Acid / Q000502:physiology*
chemical_list: D014335:Tropomyosin; D005680:gamma-Aminobutyric Acid; D020813:Receptor, trkB