title: ITSN-1 controls vesicle recycling at the neuromuscular junction and functions in parallel with DAB-1.
abstract: Intersectins (Itsn) are conserved EH and SH3 domain containing adaptor proteins. In Drosophila melanogaster, ITSN is required to regulate synaptic morphology, to facilitate efficient synaptic vesicle recycling and for viability. Here, we report our genetic analysis of Caenorhabditis elegans intersectin. In contrast to Drosophila, C. elegans itsn-1 protein null mutants are viable and display grossly normal locomotion and development. However, motor neurons in these mutants show a dramatic increase in large irregular vesicles and accumulate membrane-associated vesicles at putative endocytic hotspots, approximately 300 nm from the presynaptic density. This defect occurs precisely where endogenous ITSN-1 protein localizes in wild-type animals and is associated with a significant reduction in synaptic vesicle number and reduced frequency of endogenous synaptic events at neuromuscular junctions (NMJs). ITSN-1 forms a stable complex with EHS-1 (Eps15) and is expressed at reduced levels in ehs-1 mutants. Thus, ITSN-1 together with EHS-1, coordinate vesicle recycling at C. elegans NMJs. We also found that both itsn-1 and ehs-1 mutants show poor viability and growth in a Disabled (dab-1) null mutant background. These results show for the first time that intersectin and Eps15 proteins function in the same genetic pathway, and appear to function synergistically with the clathrin-coat-associated sorting protein, Disabled, for viability.
authors.affiliation: Program in Developmental and Stem Cell Biology, The Hospital for Sick Children. 101 College Street, TMDT East Tower, Toronto, Ontario M5G 1L7, Canada.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Magali
authors.initials: M
authors.lastname: Bouhours
authors.forename: Elena O
authors.initials: EO
authors.lastname: Gracheva
authors.forename: Edward H
authors.initials: EH
authors.lastname: Liao
authors.forename: Keli
authors.initials: K
authors.lastname: Xu
authors.forename: Ameet S
authors.initials: AS
authors.lastname: Sengar
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Xin
authors.forename: John
authors.initials: J
authors.lastname: Roder
authors.forename: Charles
authors.initials: C
authors.lastname: Boone
authors.forename: Janet E
authors.initials: JE
authors.lastname: Richmond
authors.forename: Mei
authors.initials: M
authors.lastname: Zhen
authors.forename: Sean E
authors.initials: SE
authors.lastname: Egan
mesh_terms: D033942:Adaptor Proteins, Vesicular Transport / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D030801:Animals, Genetically Modified; D017173:Caenorhabditis elegans / Q000033:anatomy & histology / Q000235:genetics / Q000502:physiology; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster; D004705:Endocytosis; D017353:Gene Deletion; D017930:Genes, Reporter; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D009469:Neuromuscular Junction / Q000502:physiology*; D018408:Patch-Clamp Techniques; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013569:Synapses / Q000378:metabolism / Q000648:ultrastructure; D009435:Synaptic Transmission / Q000502:physiology; D013572:Synaptic Vesicles / Q000378:metabolism* / Q000648:ultrastructure; D020798:Two-Hybrid System Techniques
chemical_list: D033942:Adaptor Proteins, Vesicular Transport; D029742:Caenorhabditis elegans Proteins; C510381:DAB-1 protein, C elegans; C530059:Ehs-1 protein, C elegans; C530058:ITSN-1 protein, C elegans; D047908:Intracellular Signaling Peptides and Proteins; D011993:Recombinant Fusion Proteins