Abstract
Alternative splicing of Dscam generates an enormous molecular diversity with maximally 38,016 different receptors. Whether this large diversity is required in vivo is currently unclear. We examined the role of Dscam in neuron-target recognition of single mechanosensory neurons, which connect with different target cells through multiple axonal branches. Analysis of Dscam null neurons demonstrated an essential role of Dscam for growth and directed extension of axon branches. Expression of randomly chosen single isoforms could not rescue connectivity but did restore basic axonal extension and rudimentary branching. Moreover, two Dscam alleles were generated that each reduced the maximally possible Dscam diversity to 22,176 isoforms. Reduction of Dscam diversity resulted in specific connectivity defects of mechanosensory neurons. Furthermore, the observed allele-specific phenotypes suggest functional differences among isoforms. Our findings provide evidence that a very large number of structurally unique receptor isoforms is required to ensure fidelity and precision of neuronal connectivity.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Alternative Splicing / physiology
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Animals
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Cell Adhesion Molecules
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Cell Differentiation / physiology*
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Drosophila Proteins / genetics
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Drosophila Proteins / metabolism*
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Drosophila melanogaster / cytology
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Drosophila melanogaster / embryology*
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Drosophila melanogaster / metabolism
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Genetic Variation / physiology
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Genotype
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Growth Cones / metabolism*
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Growth Cones / ultrastructure
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Mechanoreceptors / cytology
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Mechanoreceptors / embryology
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Mechanoreceptors / metabolism
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Mutation / physiology
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Nervous System / cytology
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Nervous System / embryology*
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Nervous System / metabolism
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Neural Pathways / cytology
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Neural Pathways / embryology*
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Neural Pathways / metabolism
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Neurons, Afferent / cytology
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Neurons, Afferent / metabolism
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Phenotype
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Protein Isoforms / genetics
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Protein Isoforms / metabolism
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Protein Structure, Tertiary / physiology
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Receptors, Cell Surface / genetics
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Receptors, Cell Surface / metabolism
Substances
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Cell Adhesion Molecules
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Drosophila Proteins
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Dscam1 protein, Drosophila
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Protein Isoforms
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Receptors, Cell Surface