title: Zebrafish calls for reinterpretation for the roles of P/Q calcium channels in neuromuscular transmission.
abstract: A long-held tenet of neuromuscular transmission is that calcium-dependent neurotransmitter release is mediated by N-type calcium channels in frog but P/Q-type channels in mammals. The N-type assignment in frog is based principally on pharmacological sensitivity to ω-conotoxin GVIA. Our studies show that zebrafish neuromuscular transmission is also sensitive to ω-conotoxin GVIA. However, positional cloning of a mutant line with compromised neuromuscular function identified a mutation in a P/Q- rather than N-type channel. Cloning and heterologous expression of this P/Q-type channel confirmed a block by ω-conotoxin GVIA raising the likelihood that all vertebrates, including frog, use the P/Q-type calcium channel for neuromuscular transmission. In addition, our P/Q defective mutant line offered a means of testing the ability of roscovitine, known to potentiate frog neuromuscular transmission, to mediate behavioral and functional rescue. Acute treatment led to rapid improvement of both, pointing to potential therapeutic benefit for myasthenic disorders involving calcium channel dysfunction.
authors.affiliation: Oregon Health and Science University, Portland, Oregon 97239, USA.
authors.forename: Hua
authors.initials: H
authors.lastname: Wen
authors.forename: Michael W
authors.initials: MW
authors.lastname: Linhoff
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Hubbard
authors.forename: Nathan R
authors.initials: NR
authors.lastname: Nelson
authors.forename: Donald
authors.initials: D
authors.lastname: Stensland
authors.forename: Julia
authors.initials: J
authors.lastname: Dallman
authors.forename: Gail
authors.initials: G
authors.lastname: Mandel
authors.forename: Paul
authors.initials: P
authors.lastname: Brehm
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D030801:Animals, Genetically Modified; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000235:genetics / Q000502:physiology; D020864:Calcium Channels, N-Type / Q000235:genetics / Q000502:physiology; D020865:Calcium Channels, P-Type / Q000235:genetics / Q000502:physiology*; D020907:Calcium Channels, Q-Type / Q000235:genetics / Q000502:physiology*; D003001:Cloning, Molecular; D057809:HEK293 Cells; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation / Q000502:physiology; D009469:Neuromuscular Junction / Q000235:genetics / Q000502:physiology*; D009435:Synaptic Transmission / Q000235:genetics / Q000502:physiology*; D015027:Zebrafish
chemical_list: C105656:CACNA1A protein, human; C500545:CACNA1B protein, human; D002121:Calcium Channel Blockers; D015220:Calcium Channels; D020864:Calcium Channels, N-Type; D020865:Calcium Channels, P-Type; D020907:Calcium Channels, Q-Type