title: Alpha-synuclein promotes early neurite outgrowth in cultured primary neurons.
abstract: We previously showed that alpha-synuclein (α-Syn), a protein implicated in the pathogenesis of several neurodegenerative diseases, is a microtubule-associated protein (MAP), facilitating the polymerization of tubulin into microtubules. Therefore, we hypothesized that α-Syn might promote neurite outgrowth, a process that requires microtubule assembly. To test this hypothesis, recombinant human wild type (WT) and mutant (A30P and A53T) α-Syn proteins were added to cultured primary rat cortical neurons, and their effects on early neurite outgrowth were observed. The WT and mutant α-Syn proteins entered the neurons after 1-4 h of incubation. However, a significant increase in neurite outgrowth was observed only in neurons treated with WT α-Syn. MES23.5 dopaminergic neuronal cells overexpressing WT α-Syn also exhibited enhanced neurite outgrowth, indicating that the ability of α-Syn to promote neurite outgrowth was not due to a direct action on the cell membrane or by the membrane translocation process. Co-immunoprecipitation demonstrated that the recombinant human α-Syn was bound to tubulin. In addition, the α-Syn-treated neurons displayed increased levels of polymerized tubulin. Because α-Syn's MAP functionality is mediated by specific domains, we generated N-terminal (a.a. 1-65), non-amyloid-β (non-Aβ) component (NAC) (a.a. 61-95) and C-terminal (a.a. 96-140) fragments and added them to the primary neurons. After 1-4 h of incubation, the various α-Syn fragments had entered the neurons. However, only the NAC and C-terminal fragments, which have been previously shown to mediate MAP functionality, promoted neurite outgrowth. These results suggest that α-Syn promotes neurite outgrowth by facilitating the polymerization of tubulin into microtubules.
authors: Department of Neurobiology, Beijing Institute of Geriatrics, Xuanwu Hospital of China Capital Medical University, No. 45 Changchun Street, Beijing, 100053, China.
authors: Guangwei
authors: G
authors: Liu
authors: Peng
authors: P
authors: Wang
authors: Xin
authors: X
authors: Li
authors: Yaohua
authors: Y
authors: Li
authors: Shengli
authors: S
authors: Xu
authors: Kenji
authors: K
authors: Uéda
authors: Piu
authors: P
authors: Chan
authors: Shun
authors: S
authors: Yu
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D015153:Blotting, Western; D002462:Cell Membrane / Q000378:metabolism; D002540:Cerebral Cortex / Q000166:cytology / Q000187:drug effects; D003600:Cytosol / Q000378:metabolism; D059290:Dopaminergic Neurons / Q000187:drug effects; D004926:Escherichia coli / Q000378:metabolism; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D016501:Neurites / Q000187:drug effects*; D009474:Neurons / Q000187:drug effects*; D010957:Plasmids / Q000235:genetics; D061251:Primary Cell Culture; D051381:Rats; D017208:Rats, Wistar; D011994:Recombinant Proteins / Q000494:pharmacology; D014162:Transfection; D014404:Tubulin / Q000302:isolation & purification / Q000378:metabolism; D051844:alpha-Synuclein / Q000494:pharmacology*
chemical_list: D011994:Recombinant Proteins; D014404:Tubulin; D051844:alpha-Synuclein