title: N-Acetyl-D-Glucosamine Kinase Promotes the Axonal Growth of Developing Neurons.
abstract: N-acetyl-D-glucosamine kinase (NAGK) plays an enzyme activity-independent, non-canonical role in the dendritogenesis of hippocampal neurons in culture. In this study, we investigated its role in axonal development. We found NAGK was distributed throughout neurons until developmental stage 3 (axonal outgrowth), and that its axonal expression remarkably decreased during stage 4 (dendritic outgrowth) and became negligible in stage 5 (mature). Immunocytochemistry (ICC) showed colocalization of NAGK with tubulin in hippocampal neurons and with Golgi in somata, dendrites, and nascent axons. A proximity ligation assay (PLA) for NAGK and Golgi marker protein followed by ICC for tubulin or dynein light chain roadblock type 1 (DYNLRB1) in stage 3 neurons showed NAGK-Golgi complex colocalized with DYNLRB1 at the tips of microtubule (MT) fibers in axonal growth cones and in somatodendritic areas. PLAs for NAGK-dynein combined with tubulin or Golgi ICC showed similar signal patterns, indicating a three way interaction between NAGK, dynein, and Golgi in growing axons. In addition, overexpression of the NAGK gene and of kinase mutant NAGK genes increased axonal lengths, and knockdown of NAGK by small hairpin (sh) RNA reduced axonal lengths; suggesting a structural role for NAGK in axonal growth. Finally, transfection of 'DYNLRB1 (74-96)', a small peptide derived from DYNLRB1's C-terminal, which binds with NAGK, resulted in neurons with shorter axons in culture. The authors suggest a NAGK-dynein-Golgi tripartite interaction in growing axons is instrumental during early axonal development.
authors.affiliation: Department of Anatomy, College of Medicine Dongguk University, Gyeongju 780-714, Korea.
authors.forename: Md Ariful
authors.initials: MA
authors.lastname: Islam
authors.affiliation: Department of Anatomy, College of Medicine Dongguk University, Gyeongju 780-714, Korea.
authors.forename: Syeda Ridita
authors.initials: SR
authors.lastname: Sharif
authors.affiliation: Dongguk Medical Institute, College of Medicine Dongguk University, Gyeongju 780-714, Korea.
authors.forename: HyunSook
authors.initials: H
authors.lastname: Lee
authors.affiliation: Department of Anatomy, College of Medicine Dongguk University, Gyeongju 780-714, Korea.|Dongguk Medical Institute, College of Medicine Dongguk University, Gyeongju 780-714, Korea.
authors.forename: Il Soo
authors.initials: IS
authors.lastname: Moon
mesh_terms: D000818:Animals; D001369:Axons / Q000201:enzymology / Q000502:physiology*; D002478:Cells, Cultured; D056445:Cytoplasmic Dyneins / Q000378:metabolism*; D003712:Dendrites / Q000201:enzymology / Q000502:physiology; D055785:Gene Knockdown Techniques / Q000379:methods; D006056:Golgi Apparatus / Q000378:metabolism*; D006624:Hippocampus / Q000201:enzymology / Q000502:physiology; D007150:Immunohistochemistry; D008870:Microtubules / Q000378:metabolism; D055495:Neurogenesis / Q000502:physiology*; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D061251:Primary Cell Culture; D034741:RNA, Small Interfering / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D014404:Tubulin / Q000378:metabolism
chemical_list: D034741:RNA, Small Interfering; D014404:Tubulin; D017853:Phosphotransferases (Alcohol Group Acceptor); C018716:N-acetylglucosamine kinase; D056445:Cytoplasmic Dyneins; C000604283:DYNLRB1 protein, rat
keywords: Golgi; NAGK; axon; dynein; microtubule; neuron