title: Sugar-free frosting, a homolog of SAD kinase, drives neural-specific glycan expression in the Drosophila embryo.
abstract: Precise glycan structures on specific glycoproteins impart functionalities essential for neural development. However, mechanisms controlling embryonic neural-specific glycosylation are unknown. A genetic screen for relevant mutations in Drosophila generated the sugar-free frosting (sff) mutant that reveals a new function for protein kinases in regulating substrate flux through specific Golgi processing pathways. Sff is the Drosophila homolog of SAD kinase, which regulates synaptic vesicle tethering and neuronal polarity in nematodes and vertebrates. Our Drosophila sff mutant phenotype has features in common with SAD kinase mutant phenotypes in these other organisms, but we detect altered neural glycosylation well before the initiation of embryonic synaptogenesis. Characterization of Golgi compartmentation markers indicates altered colocalization that is consistent with the detected shift in glycan complexity in sff mutant embryos. Therefore, in analogy to synaptic vesicle tethering, we propose that Sff regulates vesicle tethering at Golgi membranes in the developing Drosophila embryo. Furthermore, neuronal sff expression is dependent on transcellular signaling through a non-neural toll-like receptor, linking neural-specific glycan expression to a kinase activity that is induced in response to environmental cues.
authors.affiliation: Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA 30602-4712, USA.
authors.forename: Sarah
authors.initials: S
authors.lastname: Baas
authors.forename: Mary
authors.initials: M
authors.lastname: Sharrow
authors.forename: Varshika
authors.initials: V
authors.lastname: Kotu
authors.forename: Meg
authors.initials: M
authors.lastname: Middleton
authors.forename: Khoi
authors.initials: K
authors.lastname: Nguyen
authors.forename: Heather
authors.initials: H
authors.lastname: Flanagan-Steet
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Aoki
authors.forename: Michael
authors.initials: M
authors.lastname: Tiemeyer
mesh_terms: D000818:Animals; D002853:Chromatography, Liquid; D004330:Drosophila / Q000196:embryology* / Q000201:enzymology*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004625:Embryo, Nonmammalian / Q000201:enzymology*; D006031:Glycosylation; D006056:Golgi Apparatus / Q000378:metabolism; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D007425:Intracellular Membranes / Q000378:metabolism; D018613:Microscopy, Confocal; D011134:Polysaccharides / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D053719:Tandem Mass Spectrometry
chemical_list: D029721:Drosophila Proteins; D011134:Polysaccharides