title: Neurofilaments can undergo axonal transport and cytoskeletal incorporation in a discontinuous manner.
abstract: Neurofilaments (NFs) are thought to provide structural support for axons. Some NFs exhibit an extended residence time along axons, the nature of which remains unclear. In prior studies in NB2a/d1 cells, hypophosphorylated NFs were demonstrated to be dispersed throughout the axon and to undergo relatively rapid axonal transport, while extensively phosphorylated NFs organized into a "bundle" localized along the center of the axon. It was not conclusively determined whether bundled NFs underwent transport or instead underwent turnover via exchange with transporting individual NFs. Herein, using transfection with multiple constructs and regional photobleaching, we demonstrate that bundled NFs undergo relatively slow transport as well as exchange with surrounding individual NFs. We also demonstrate that newly synthesized NFs disperse nonhomogenously throughout axonal neurites and perikarya. These findings provide a mechanism by which some NFs exhibit extended residence time within axons, which lessens the metabolic burden of cytoskeletal turnover.
authors.affiliation: Center for Cellular Neurobiology and Neurodegeneration Research, Department of Biological Sciences, University of Massachusetts-Lowell, One University Avenue Lowell, Massachusetts 01854, USA.
authors.forename: Walter K-H
authors.initials: WK
authors.lastname: Chan
authors.forename: Jason T
authors.initials: JT
authors.lastname: Yabe
authors.forename: Aurea F
authors.initials: AF
authors.lastname: Pimenta
authors.forename: Daniela
authors.initials: D
authors.lastname: Ortiz
authors.forename: Thomas B
authors.initials: TB
authors.lastname: Shea
mesh_terms: D000818:Animals; D001370:Axonal Transport / Q000502:physiology*; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000378:metabolism* / Q000648:ultrastructure; D049452:Green Fluorescent Proteins / Q000032:analysis / Q000096:biosynthesis / Q000235:genetics; D015151:Immunoblotting; D051379:Mice; D018613:Microscopy, Confocal; D016900:Neurofilament Proteins / Q000378:metabolism*; D038761:Photobleaching; D014162:Transfection
chemical_list: D016900:Neurofilament Proteins; D049452:Green Fluorescent Proteins