Synaptic calcium-channel function in Drosophila: Analysis and transformation rescue of temperature-sensitive paralytic and lethal mutations of Cacophony

Fumiko Kawasaki, Stephen C. Collins, Richard W. Ordway

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64 Citations (Scopus)

Abstract

Voltage-gated calcium channels play a key role in chemical synaptic transmission by providing the calcium trigger for regulated neurotransmitter release. Genes encoding the primary structural subunit, α1, as well as accessory subunits of presynaptic calcium channels have now been identified in a variety of organisms. The cacophony (cac) gene in Drosophila, also known as nightblind A, encodes a voltage-gated calcium-channel α1 subunit homologous to vertebrate α1 subunits implicated in neurotransmitter release. A recent genetic screen in our laboratory isolated cacTS2, a conditional cac mutant exhibiting rapid paralysis at elevated temperatures. This mutant has allowed synaptic electrophysiology after acute perturbation of a specific calcium-channel gene product, demonstrating that cac encodes a primary calcium channel functioning in neurotransmitter release. Here we report the molecular lesion in cacTS2, a missense mutation within a calcium-dependent regulatory domain of the α1 subunit, as well as phenotypic rescue of temperature-sensitive and lethal cac mutations by transgenic expression of a wild-type cac cDNA. Notably, rescue of rapid, calcium-triggered neurotransmitter release was achieved by neural expression of a single cDNA containing a subset of alternative exons and lacking any conserved synaptic-protein interaction sequence. Possible implications of these findings are discussed in the context of structure-function studies of synaptic calcium channels, as well as alternative splicing and mRNA editing of the cac transcript.

Original languageEnglish (US)
Pages (from-to)5856-5864
Number of pages9
JournalJournal of Neuroscience
Volume22
Issue number14
StatePublished - Jul 15 2002

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Calcium Channels
Drosophila
Mutation
Temperature
Neurotransmitter Agents
Calcium
Complementary DNA
Genes
Electrophysiology
Alternative Splicing
Missense Mutation
Synaptic Transmission
Paralysis
Vertebrates
Exons
Messenger RNA
Proteins

All Science Journal Classification (ASJC) codes

  • Neuroscience(all)

Cite this

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abstract = "Voltage-gated calcium channels play a key role in chemical synaptic transmission by providing the calcium trigger for regulated neurotransmitter release. Genes encoding the primary structural subunit, α1, as well as accessory subunits of presynaptic calcium channels have now been identified in a variety of organisms. The cacophony (cac) gene in Drosophila, also known as nightblind A, encodes a voltage-gated calcium-channel α1 subunit homologous to vertebrate α1 subunits implicated in neurotransmitter release. A recent genetic screen in our laboratory isolated cacTS2, a conditional cac mutant exhibiting rapid paralysis at elevated temperatures. This mutant has allowed synaptic electrophysiology after acute perturbation of a specific calcium-channel gene product, demonstrating that cac encodes a primary calcium channel functioning in neurotransmitter release. Here we report the molecular lesion in cacTS2, a missense mutation within a calcium-dependent regulatory domain of the α1 subunit, as well as phenotypic rescue of temperature-sensitive and lethal cac mutations by transgenic expression of a wild-type cac cDNA. Notably, rescue of rapid, calcium-triggered neurotransmitter release was achieved by neural expression of a single cDNA containing a subset of alternative exons and lacking any conserved synaptic-protein interaction sequence. Possible implications of these findings are discussed in the context of structure-function studies of synaptic calcium channels, as well as alternative splicing and mRNA editing of the cac transcript.",
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