title: TUC-4b, a novel TUC family variant, regulates neurite outgrowth and associates with vesicles in the growth cone.
abstract: The TUC (TOAD-64/Ulip/CRMP) proteins are homologs of UNC-33, a protein that is required for axon extension and guidance in Caenorhabditis elegans. The TUC proteins are expressed in newly born neurons in the developing nervous system and have been implicated in semaphorin signaling and neuronal polarity. Here, we identify several new variants of the TUC family, each of which is expressed during distinct periods of neural development. We cloned and characterized TUC-4b, a variant of TUC-4a that includes a unique N-terminal extension. The functional relevance of this N-terminal domain is demonstrated by the finding that overexpression of TUC-4b, but not TUC-4a, results in increased neurite length and branching. Furthermore, whereas TUC-4a is expressed throughout life, TUC-4b is expressed exclusively during embryonic development. TUC-4b is localized to SV2 (synaptic vesicle protein 2)-positive vesicles in the central domain of the growth cone, suggesting a potential role in growth cone vesicle transport. Furthermore, TUC-4b interacts with the SH3A (Src homology 3A) domain of intersectin, an endocytic-exocytic adaptor protein. Together, these data suggest that TUC-4b can regulate neurite extension and branching through a mechanism that may involve membrane transport in the growth cone.
authors.affiliation: Section of Neurobiology, Yale University School of Medicine, New Haven, Connecticut 06510, USA. quinncc@umdnj.edu
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Quinn
authors.forename: Esteban
authors.initials: E
authors.lastname: Chen
authors.forename: Tashi G
authors.initials: TG
authors.lastname: Kinjo
authors.forename: Gail
authors.initials: G
authors.lastname: Kelly
authors.forename: Alexander W
authors.initials: AW
authors.lastname: Bell
authors.forename: Robert C
authors.initials: RC
authors.lastname: Elliott
authors.forename: Peter S
authors.initials: PS
authors.lastname: McPherson
authors.forename: Susan
authors.initials: S
authors.lastname: Hockfield
mesh_terms: D033942:Adaptor Proteins, Vesicular Transport; D000595:Amino Acid Sequence; D000818:Animals; D001369:Axons / Q000502:physiology / Q000648:ultrastructure; D029742:Caenorhabditis elegans Proteins / Q000032:analysis* / Q000235:genetics / Q000502:physiology*; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism; D003001:Cloning, Molecular; D020439:Growth Cones / Q000737:chemistry*; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000032:analysis* / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D009420:Nervous System / Q000196:embryology / Q000378:metabolism; D016501:Neurites / Q000648:ultrastructure*; D020033:Protein Isoforms / Q000032:analysis / Q000737:chemistry; D051381:Rats; D017207:Rats, Sprague-Dawley; D013572:Synaptic Vesicles / Q000737:chemistry* / Q000502:physiology; D018909:src Homology Domains
chemical_list: D033942:Adaptor Proteins, Vesicular Transport; D029742:Caenorhabditis elegans Proteins; D002352:Carrier Proteins; D009419:Nerve Tissue Proteins; D020033:Protein Isoforms; C115919:intersectin 1