title: Drosophila sec10 is required for hormone secretion but not general exocytosis or neurotransmission.
abstract: The sec6/8, or exocyst, complex is implicated in trafficking of secretory vesicles to fusion sites in the plasma membrane. Genetic analyses have been done primarily in yeast, where mutation of the eight protein subunits similarly disrupts polarized vesicle fusion. The goal of this study was to assay the sec6/8 complex in Drosophila, and specifically to test its widely hypothesized functions in synaptogenesis and neurotransmission. We used a transgenic RNAi approach to remove the most highly conserved complex component, Drosophila sec10 (dSec10). Ubiquitous dSec10 RNAi resulted in early postembryonic lethality, demonstrating that dSec10 is essential. Surprisingly, tissue-specific dSec10 RNAi revealed no essential requirement in nervous system, musculature, gut or epidermis. Assays of polarized secretion in all these tissues failed to reveal any role for dSec10. In particular, the neuromuscular synapse showed no defects in morphogenesis or vesicle trafficking/fusion underlying neurotransmission. The essential requirement for dSec10 was restricted to the ring gland, the Drosophila organ specialized for endocrine function. The developmental arrest of dSec10 RNAi animals was partially rescued by feeding ecdysone, suggesting dSec10 mediates steroid hormone secretion. We conclude that dSec10 has no detectable role in most forms of polarized trafficking/exocytosis, including neurotransmission, but rather is essential for endocrine secretion.
authors.affiliation: Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235-1634, USA.
authors.forename: Hillary K
authors.initials: HK
authors.lastname: Andrews
authors.forename: Yong Q
authors.initials: YQ
authors.lastname: Zhang
authors.forename: Nick
authors.initials: N
authors.lastname: Trotta
authors.forename: Kendal
authors.initials: K
authors.lastname: Broadie
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D002352:Carrier Proteins / Q000737:chemistry* / Q000502:physiology*; D004330:Drosophila / Q000235:genetics* / Q000378:metabolism; D029721:Drosophila Proteins / Q000737:chemistry* / Q000502:physiology*; D004440:Ecdysone / Q000494:pharmacology; D004594:Electrophysiology; D005091:Exons; D020224:Expressed Sequence Tags; D049452:Green Fluorescent Proteins; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D007438:Introns; D008164:Luminescent Proteins / Q000378:metabolism; D026901:Membrane Transport Proteins; D009154:Mutation; D034622:RNA Interference; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D013997:Time Factors; D019076:Transgenes
chemical_list: D002352:Carrier Proteins; D029721:Drosophila Proteins; D008164:Luminescent Proteins; D026901:Membrane Transport Proteins; D011993:Recombinant Fusion Proteins; C474345:sec10 protein, Drosophila; D049452:Green Fluorescent Proteins; D004440:Ecdysone