title: Arf6 guanine nucleotide exchange factor cytohesin-2 binds to CCDC120 and is transported along neurites to mediate neurite growth.
abstract: The mechanism of neurite growth is complicated, involving continuous cytoskeletal rearrangement and vesicular trafficking. Cytohesin-2 is a guanine nucleotide exchange factor for Arf6, an Arf family molecular switch protein, controlling cell morphological changes such as neuritogenesis. Here, we show that cytohesin-2 binds to a protein with a previously unknown function, CCDC120, which contains three coiled-coil domains, and is transported along neurites in differentiating N1E-115 cells. Transfection of the small interfering RNA (siRNA) specific for CCDC120 into cells inhibits neurite growth and Arf6 activation. When neurites start to extend, vesicles containing CCDC120 and cytohesin-2 are transported in an anterograde manner rather than a retrograde one. As neurites continue extension, anterograde vesicle transport decreases. CCDC120 knockdown inhibits cytohesin-2 localization into vesicles containing CCDC120 and diffuses cytohesin-2 in cytoplasmic regions, illustrating that CCDC120 determines cytohesin-2 localization in growing neurites. Reintroduction of the wild type CCDC120 construct into cells transfected with CCDC120 siRNA reverses blunted neurite growth and Arf6 activity, whereas the cytohesin-2-binding CC1 region-deficient CCDC120 construct does not. Thus, cytohesin-2 is transported along neurites by vesicles containing CCDC120, and it mediates neurite growth. These results suggest a mechanism by which guanine nucleotide exchange factor for Arf6 is transported to mediate neurite growth.
authors.affiliation: From the Department of Pharmacology, National Research Institute for Child Health and Development, Setagaya, Tokyo 157-8535, torii-t@ncchd.go.jp.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Torii
authors.affiliation: From the Department of Pharmacology, National Research Institute for Child Health and Development, Setagaya, Tokyo 157-8535.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Miyamoto
authors.affiliation: the Graduate School of Medicine, Jichi Medical University, Shimotsuke, Tochigi 329-0498.
authors.forename: Kenji
authors.initials: K
authors.lastname: Tago
authors.affiliation: the Amyotrophic Lateral Sclerosis/Neuropathy Project, Tokyo Metropolitan Institute of Medical Science, Setagaya, Tokyo 156-8506.
authors.forename: Kazunori
authors.initials: K
authors.lastname: Sango
authors.affiliation: From the Department of Pharmacology, National Research Institute for Child Health and Development, Setagaya, Tokyo 157-8535.
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Nakamura
authors.affiliation: the School of Pharmacy, Iwate Medical University, Morioka, Iwate 020-0023, and.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Sanbe
authors.affiliation: From the Department of Pharmacology, National Research Institute for Child Health and Development, Setagaya, Tokyo 157-8535.
authors.forename: Akito
authors.initials: A
authors.lastname: Tanoue
authors.affiliation: From the Department of Pharmacology, National Research Institute for Child Health and Development, Setagaya, Tokyo 157-8535, the Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyo, Tokyo 113-8510, Japan yamauchi-j@ncchd.go.jp.
authors.forename: Junji
authors.initials: J
authors.lastname: Yamauchi
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D020690:GTPase-Activating Proteins / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism; D055495:Neurogenesis / Q000235:genetics*; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D022161:Transport Vesicles / Q000378:metabolism*
chemical_list: C000595666:CCDC120 protein, human; D020690:GTPase-Activating Proteins; D009419:Nerve Tissue Proteins; D034741:RNA, Small Interfering; C102474:cytohesin-2
keywords: ADP Ribosylation Factor (ARF); GTPase; Guanine Nucleotide Exchange Factor (GEF); Neurite Outgrowth; Vesicles