Abstract
Classical cadherins have been proposed to mediate interactions between pre- and postsynaptic cells that are necessary for synapse formation. We provide the first direct, genetic evidence in favor of this model by examining the role of N-cadherin in controlling the pattern of synaptic connections made by photoreceptor axons in Drosophila. N-cadherin is required in both individual photoreceptors and their target neurons for photoreceptor axon extension. Cell-by-cell reconstruction of wild-type photoreceptor axons extending within mosaic patches of mutant target cells shows that N-cadherin mediates attractive interactions between photoreceptors and their targets. This interaction is not limited to those cells that will become the synaptic partners of photoreceptors. Multiple N-cadherin isoforms are produced, but single isoforms can substitute for endogenous N-cadherin activity. We propose that N-cadherin mediates a homophilic, attractive interaction between photoreceptor growth cones and their targets that precedes synaptic partner choice.
Publication types
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Comparative Study
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Animals
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Animals, Genetically Modified
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Axons / physiology*
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Cadherins / metabolism
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Cadherins / physiology*
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Drosophila / physiology*
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Drosophila Proteins
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ELAV Proteins
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Gene Deletion
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Gene Expression Regulation, Developmental
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Green Fluorescent Proteins / metabolism
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Immunohistochemistry / methods
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Membrane Glycoproteins / metabolism
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Microscopy, Confocal / methods
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Models, Neurological
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Mutagenesis / physiology
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Mutagenesis / radiation effects
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Nerve Tissue Proteins / metabolism
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Neurons / metabolism*
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Photoreceptor Cells, Invertebrate / cytology*
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Photoreceptor Cells, Invertebrate / physiology
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RNA, Messenger / metabolism
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RNA-Binding Proteins / metabolism
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Reverse Transcriptase Polymerase Chain Reaction / methods
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Synapses / metabolism*
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beta-Galactosidase / metabolism
Substances
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Cadherins
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Drosophila Proteins
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ELAV Proteins
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Membrane Glycoproteins
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Nerve Tissue Proteins
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RNA, Messenger
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RNA-Binding Proteins
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chp protein, Drosophila
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Green Fluorescent Proteins
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beta-Galactosidase