title: Orchestration of stepwise synaptic growth by K+ and Ca2+ channels in Drosophila.
abstract: Synapse formation is tightly associated with neuronal excitability. We found striking synaptic overgrowth caused by Drosophila K(+)-channel mutations of the seizure and slowpoke genes, encoding Erg and Ca(2+)-activated large-conductance (BK) channels, respectively. These mutants display two distinct patterns of "satellite" budding from larval motor terminus synaptic boutons. Double-mutant analysis indicates that BK and Erg K(+) channels interact with separate sets of synaptic proteins to affect distinct growth steps. Post-synaptic L-type Ca(2+) channels, Dmca1D, and PSD-95-like scaffold protein, Discs large, are required for satellite budding induced by slowpoke and seizure mutations. Pre-synaptic cacophony Ca(2+) channels and the NCAM-like adhesion molecule, Fasciclin II, take part in a maturation step that is partially arrested by seizure mutations. Importantly, slowpoke and seizure satellites were both suppressed by rutabaga mutations that disrupt Ca(2+)/CaM-dependent adenylyl cyclase, demonstrating a convergence of K(+) channels of different functional categories in regulation of excitability-dependent Ca(2+) influx for triggering cAMP-mediated growth plasticity.
authors.affiliation: Department of Biology, The University of Iowa, Iowa City, IA 52242, USA. ihyelee@mit.edu
authors.forename: Jihye
authors.initials: J
authors.lastname: Lee
authors.forename: Chun-Fang
authors.initials: CF
authors.lastname: Wu
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D015220:Calcium Channels / Q000235:genetics / Q000502:physiology*; D029721:Drosophila Proteins / Q000235:genetics / Q000502:physiology*; D004331:Drosophila melanogaster / Q000235:genetics / Q000254:growth & development*; D051036:Large-Conductance Calcium-Activated Potassium Channels / Q000235:genetics / Q000502:physiology; D007814:Larva / Q000235:genetics / Q000254:growth & development; D009154:Mutation; D015221:Potassium Channels / Q000235:genetics / Q000502:physiology*; D013569:Synapses / Q000235:genetics / Q000502:physiology*
chemical_list: D015220:Calcium Channels; D029721:Drosophila Proteins; D051036:Large-Conductance Calcium-Activated Potassium Channels; D015221:Potassium Channels; C494844:slo protein, Drosophila