title: Intersectin regulates dendritic spine development and somatodendritic endocytosis but not synaptic vesicle recycling in hippocampal neurons.
abstract: Intersectin-short (intersectin-s) is a multimodule scaffolding protein functioning in constitutive and regulated forms of endocytosis in non-neuronal cells and in synaptic vesicle (SV) recycling at the neuromuscular junction of Drosophila and Caenorhabditis elegans. In vertebrates, alternative splicing generates a second isoform, intersectin-long (intersectin-l), that contains additional modular domains providing a guanine nucleotide exchange factor activity for Cdc42. In mammals, intersectin-s is expressed in multiple tissues and cells, including glia, but excluded from neurons, whereas intersectin-l is a neuron-specific isoform. Thus, intersectin-I may regulate multiple forms of endocytosis in mammalian neurons, including SV endocytosis. We now report, however, that intersectin-l is localized to somatodendritic regions of cultured hippocampal neurons, with some juxtanuclear accumulation, but is excluded from synaptophysin-labeled axon terminals. Consistently, intersectin-l knockdown (KD) does not affect SV recycling. Instead intersectin-l co-localizes with clathrin heavy chain and adaptor protein 2 in the somatodendritic region of neurons, and its KD reduces the rate of transferrin endocytosis. The protein also co-localizes with F-actin at dendritic spines, and intersectin-l KD disrupts spine maturation during development. Our data indicate that intersectin-l is indeed an important regulator of constitutive endocytosis and neuronal development but that it is not a prominent player in the regulated endocytosis of SVs.
authors.affiliation: Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec H3A 2B4, Canada.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Thomas
authors.forename: Brigitte
authors.initials: B
authors.lastname: Ritter
authors.forename: David
authors.initials: D
authors.lastname: Verbich
authors.forename: Claire
authors.initials: C
authors.lastname: Sanson
authors.forename: Lyne
authors.initials: L
authors.lastname: Bourbonnière
authors.forename: R Anne
authors.initials: RA
authors.lastname: McKinney
authors.forename: Peter S
authors.initials: PS
authors.lastname: McPherson
mesh_terms: D000199:Actins / Q000235:genetics / Q000378:metabolism; D033942:Adaptor Proteins, Vesicular Transport / Q000235:genetics / Q000378:metabolism*; D017398:Alternative Splicing / Q000502:physiology; D000818:Animals; D001369:Axons / Q000378:metabolism; D017173:Caenorhabditis elegans; D033922:Clathrin Heavy Chains / Q000235:genetics / Q000378:metabolism; D049229:Dendritic Spines / Q000378:metabolism*; D004331:Drosophila melanogaster; D004705:Endocytosis / Q000502:physiology*; D055785:Gene Knockdown Techniques; D006624:Hippocampus / Q000166:cytology / Q000378:metabolism*; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary / Q000502:physiology; D051381:Rats; D013572:Synaptic Vesicles / Q000235:genetics / Q000378:metabolism*
chemical_list: D000199:Actins; D033942:Adaptor Proteins, Vesicular Transport; D020033:Protein Isoforms; C115919:intersectin 1; D033922:Clathrin Heavy Chains