In vivo induction of postsynaptic molecular assembly by the cell adhesion molecule Fasciclin2.
Cell adhesion molecules (CAMs) are thought to mediate interactions between innervating axons and their targets. However, such interactions have not been directly observed in vivo. In this paper, we study the function and dynamics of Fasciclin2 (Fas2), a homophilic CAM expressed both pre- and postsynaptically during neuromuscular synapse formation in Drosophila melanogaster. We apply live imaging of functional fluorescent fusion proteins expressed in muscles and find that Fas2 and Discs-Large (Dlg; a scaffolding protein known to bind Fas2) accumulate at the synaptic contact site soon after the arrival of the nerve. Genetic, deletion, and photobleaching analyses suggest that Fas2-mediated trans-synaptic adhesion is important for the postsynaptic accumulation of both Fas2 itself and Dlg. In fas2 mutants, many aspects of synapse formation appear normal; however, we see a reduction in the synaptic accumulation of Scribble (another scaffolding protein) and glutamate receptor subunits GluRIIA and GluRIIB. We propose that Fas2 mediates trans-synaptic adhesion, which contributes to postsynaptic molecular assembly at the onset of synaptogenesis.
Kohsaka
Hiroshi
H
Department of Physics, Graduate School of Science, Graduate School of Frontier Sciences, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.
Takasu
Etsuko
E
Nose
Akinao
A
D000818:Animals; D015816:Cell Adhesion Molecules, Neuronal / Q000032:analysis / Q000378:metabolism / Q000502:physiology*; D029721:Drosophila Proteins / Q000032:analysis / Q000378:metabolism / Q000502:physiology*; D004331:Drosophila melanogaster / Q000235:genetics / Q000378:metabolism*; D036681:Fluorescence Recovery After Photobleaching; D008164:Luminescent Proteins / Q000032:analysis; D008954:Models, Biological; D021122:Protein Subunits / Q000378:metabolism; D017470:Receptors, Glutamate / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000032:analysis; D013569:Synapses / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000378:metabolism
D015816:Cell Adhesion Molecules, Neuronal; D029721:Drosophila Proteins; D008164:Luminescent Proteins; D021122:Protein Subunits; D017470:Receptors, Glutamate; D011993:Recombinant Fusion Proteins; D025521:Tumor Suppressor Proteins; C051642:fasciclin II; C070350:dlg1 protein, Drosophila