title: Neurexin in embryonic Drosophila neuromuscular junctions.
abstract: BACKGROUND
  Neurexin is a synaptic cell adhesion protein critical for synapse formation and function. Mutations in neurexin and neurexin-interacting proteins have been implicated in several neurological diseases. Previous studies have described Drosophila neurexin mutant phenotypes in third instar larvae and adults. However, the expression and function of Drosophila neurexin early in synapse development, when neurexin function is thought to be most important, has not been described.
  
  
  RESULTS
  We use a variety of techniques, including immunohistochemistry, electron microscopy, in situ hybridization, and electrophysiology, to characterize neurexin expression and phenotypes in embryonic Drosophila neuromuscular junctions (NMJs). Our results surprisingly suggest that neurexin in embryos is present both pre and postsynaptically. Presynaptic neurexin promotes presynaptic active zone formation and neurotransmitter release, but along with postsynaptic neurexin, also suppresses formation of ectopic glutamate receptor clusters. Interestingly, we find that loss of neurexin only affects receptors containing the subunit GluRIIA.
  
  
  CONCLUSIONS
  Our study extends previous results and provides important detail regarding the role of neurexin in Drosophila glutamate receptor abundance. The possibility that neurexin is present postsynaptically raises new hypotheses regarding neurexin function in synapses, and our results provide new insights into the role of neurexin in synapse development.
authors.affiliation: Biological Sciences, University of Illinois at Chicago, Chicago, Illinois, United States of America.
authors.forename: Kaiyun
authors.initials: K
authors.lastname: Chen
authors.forename: Elena O
authors.initials: EO
authors.lastname: Gracheva
authors.forename: Szi-Chieh
authors.initials: SC
authors.lastname: Yu
authors.forename: Qi
authors.initials: Q
authors.lastname: Sheng
authors.forename: Janet
authors.initials: J
authors.lastname: Richmond
authors.forename: David E
authors.initials: DE
authors.lastname: Featherstone
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D015816:Cell Adhesion Molecules, Neuronal / Q000235:genetics / Q000378:metabolism*; D004330:Drosophila / Q000196:embryology*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D017403:In Situ Hybridization; D016253:Microscopy, Immunoelectron; D009469:Neuromuscular Junction / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics
chemical_list: D015816:Cell Adhesion Molecules, Neuronal; D029721:Drosophila Proteins; C491321:Nrx protein, Drosophila; D012333:RNA, Messenger