title: The Extracellular and Cytoplasmic Domains of Syndecan Cooperate Postsynaptically to Promote Synapse Growth at the Drosophila Neuromuscular Junction.
abstract: The heparan sulfate proteoglycan (HSPG) Syndecan (Sdc) is a crucial regulator of synapse development and growth in both vertebrates and invertebrates. In Drosophila, Sdc binds via its extracellular heparan sulfate (HS) sidechains to the receptor protein tyrosine phosphatase LAR to promote the morphological growth of the neuromuscular junction (NMJ). To date, however, little else is known about the molecular mechanisms by which Sdc functions to promote synapse growth. Here we show that all detectable Sdc found at the NMJ is provided by the muscle, strongly suggesting a post-synaptic role for Sdc. We also show that both the cytoplasmic and extracellular domains of Sdc are required to promote synapse growth or to rescue Sdc loss of function. We report the results of a yeast two-hybrid screen using the cytoplasmic domains of Sdc as bait, and identify several novel candidate binding partners for the cytoplasmic domains of Sdc. Together, these studies provide new insight into the mechanism of Sdc function at the NMJ, and provide enticing future directions for further exploring how Sdc promotes synapse growth.
authors.affiliation: Neuroscience Department, Pomona College, Claremont, California, United States of America.
authors.forename: Margaret U
authors.initials: MU
authors.lastname: Nguyen
authors.affiliation: Molecular Biology Program, Pomona College, Claremont, California, United States of America.
authors.forename: Jereen
authors.initials: J
authors.lastname: Kwong
authors.affiliation: Molecular Biology Program, Pomona College, Claremont, California, United States of America.
authors.forename: Julia
authors.initials: J
authors.lastname: Chang
authors.affiliation: Neuroscience Department, Pomona College, Claremont, California, United States of America.
authors.forename: Victoria G
authors.initials: VG
authors.lastname: Gillet
authors.affiliation: Neuroscience Department, Pomona College, Claremont, California, United States of America.
authors.forename: Rachel M
authors.initials: RM
authors.lastname: Lee
authors.affiliation: Molecular Biology Program, Pomona College, Claremont, California, United States of America.|Neuroscience Department, Pomona College, Claremont, California, United States of America.
authors.forename: Karl Gregory
authors.initials: KG
authors.lastname: Johnson
mesh_terms: D000818:Animals; D004330:Drosophila; D029721:Drosophila Proteins / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000378:metabolism; D009469:Neuromuscular Junction / Q000378:metabolism*; D013569:Synapses / Q000378:metabolism*; D009435:Synaptic Transmission / Q000502:physiology; D053667:Syndecans / Q000378:metabolism*
chemical_list: D029721:Drosophila Proteins; D053667:Syndecans