%0 Journal Article
%T Increased synaptic microtubules and altered synapse development in Drosophila sec8 mutants
%A Faith LW Liebl
%A Kaiyun Chen
%A Julie Karr
%A Qi Sheng
%A David E Featherstone
%J BMC Biology
%D 2005
%I BioMed Central
%R 10.1186/1741-7007-3-27
%X We identified lethal sec8 mutants in an unbiased forward genetic screen for mutations causing defects in development of glutamatergic Drosophila neuromuscular junctions (NMJs). The Drosophila NMJ is genetically malleable and accessible throughout development to electrophysiology and immunocytochemistry, making it ideal for examination of the sec8 mutant synaptic phenotype. We developed antibodies to Drosophila Sec8 and showed that Sec8 is abundant at the NMJ. In our sec8 null mutants, in which the sec8 gene is specifically deleted, Sec8 immunoreactivity at the NMJ is eliminated but immunoblots reveal substantial maternal contribution in the rest of the animal. Contrary to the hypothesis that Sec8 is required for neurite outgrowth or synaptic terminal growth, immunocytochemical examination revealed that sec8 mutant NMJs developed more branches and presynaptic terminals during larval development, compared to controls. Synaptic electrophysiology showed no evidence that Sec8 is required for basal neurotransmission, though glutamate receptor trafficking was mildly disrupted in sec8 mutants. The most dramatic NMJ phenotype in sec8 mutants was an increase in synaptic microtubule density, which was approximately doubled compared to controls.Sec8 is abundant in the Drosophila NMJ. Sec8 is required in vivo for regulation of synaptic microtubule formation, and (probably secondarily) regulation of synaptic growth and glutamate receptor trafficking. We did not find any evidence that Sec8 is required for basal neurotransmission.The Sec6/8 complex, or 'exocyst', is an octomeric protein complex thought to comprise the proteins Sec3, Sec5, Sec6, Sec8, Sec10, Sec15, Exo70 and Exo84. This complex has been most extensively studied in yeast, where it is required for membrane trafficking and secretion [1,2]. In multicellular organisms, Sec proteins are expressed at particularly high levels in the nervous system [3,4]. The functional role of Sec proteins in neurons, however, including whe
%U http://www.biomedcentral.com/1741-7007/3/27