title: A targeted glycan-related gene screen reveals heparan sulfate proteoglycan sulfation regulates WNT and BMP trans-synaptic signaling.
abstract: A Drosophila transgenic RNAi screen targeting the glycan genome, including all N/O/GAG-glycan biosynthesis/modification enzymes and glycan-binding lectins, was conducted to discover novel glycan functions in synaptogenesis. As proof-of-product, we characterized functionally paired heparan sulfate (HS) 6-O-sulfotransferase (hs6st) and sulfatase (sulf1), which bidirectionally control HS proteoglycan (HSPG) sulfation. RNAi knockdown of hs6st and sulf1 causes opposite effects on functional synapse development, with decreased (hs6st) and increased (sulf1) neurotransmission strength confirmed in null mutants. HSPG co-receptors for WNT and BMP intercellular signaling, Dally-like Protein and Syndecan, are differentially misregulated in the synaptomatrix of these mutants. Consistently, hs6st and sulf1 nulls differentially elevate both WNT (Wingless; Wg) and BMP (Glass Bottom Boat; Gbb) ligand abundance in the synaptomatrix. Anterograde Wg signaling via Wg receptor dFrizzled2 C-terminus nuclear import and retrograde Gbb signaling via synaptic MAD phosphorylation and nuclear import are differentially activated in hs6st and sulf1 mutants. Consequently, transcriptional control of presynaptic glutamate release machinery and postsynaptic glutamate receptors is bidirectionally altered in hs6st and sulf1 mutants, explaining the bidirectional change in synaptic functional strength. Genetic correction of the altered WNT/BMP signaling restores normal synaptic development in both mutant conditions, proving that altered trans-synaptic signaling causes functional differentiation defects.
authors.affiliation: Department of Biological Sciences and Department of Cell and Developmental Biology, Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, Tennessee, United States of America.
authors.forename: Neil
authors.initials: N
authors.lastname: Dani
authors.forename: Minyeop
authors.initials: M
authors.lastname: Nahm
authors.forename: Seungbok
authors.initials: S
authors.lastname: Lee
authors.forename: Kendal
authors.initials: K
authors.lastname: Broadie
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D019485:Bone Morphogenetic Proteins / Q000378:metabolism*; D029721:Drosophila Proteins / Q000235:genetics*; D004331:Drosophila melanogaster / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D018507:Gene Expression Regulation, Developmental; D015316:Genetic Therapy; D006497:Heparan Sulfate / Q000378:metabolism; D011134:Polysaccharides / Q000378:metabolism; D011509:Proteoglycans / Q000378:metabolism; D015398:Signal Transduction; D013429:Sulfatases / Q000235:genetics*; D015238:Sulfotransferases / Q000235:genetics*; D013569:Synapses / Q000201:enzymology / Q000235:genetics / Q000473:pathology; D009435:Synaptic Transmission / Q000235:genetics; D060449:Wnt Signaling Pathway
chemical_list: D019485:Bone Morphogenetic Proteins; D029721:Drosophila Proteins; D006497:Heparan Sulfate; D011134:Polysaccharides; D011509:Proteoglycans; D013429:Sulfatases; D015238:Sulfotransferases; C404189:heparan sulfate 6-O-sulfotransferase; C568065:SULF1 protein, Drosophila