ITSN-1 Controls Vesicle Recycling at the Neuromuscular Junction and Functions in Parallel with DAB-1

• Published in: Traffic (Copenhagen, Denmark) Vol. 9; no. 5; pp. 742 - 754
• Main Authors: Wang, Wei, Bouhours, Magali, Gracheva, Elena O, Liao, Edward H, Xu, Keli, Sengar, Ameet S, Xin, Xiaofeng, Roder, John, Boone, Charles, Richmond, Janet E, Zhen, Mei, Egan, Sean E
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01.05.2008; Blackwell Publishing Ltd
• Subjects: Adaptor Proteins, Vesicular Transport - genetics; Adaptor Proteins, Vesicular Transport - metabolism; Animals; Animals, Genetically Modified; Caenorhabditis elegans; Caenorhabditis elegans - anatomy & histology; Caenorhabditis elegans - genetics; Caenorhabditis elegans - physiology; Caenorhabditis elegans Proteins - genetics; Caenorhabditis elegans Proteins - metabolism; Dab; Drosophila melanogaster; Endocytosis; Eps15; Gene Deletion; Genes, Reporter; Humans; intersectin; Intracellular Signaling Peptides and Proteins - genetics; Intracellular Signaling Peptides and Proteins - metabolism; Neuromuscular Junction - physiology; Patch-Clamp Techniques; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; Synapses - metabolism; Synapses - ultrastructure; Synaptic Transmission - physiology; synaptic vesicle; Synaptic Vesicles - metabolism; Synaptic Vesicles - ultrastructure; Two-Hybrid System Techniques
• ISSN: 1398-9219; 1600-0854
• DOI: 10.1111/j.1600-0854.2008.00712.x

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.