Kinesin-mediated transport of neurofilament protein oligomers in growing axons.
We examined cytoskeleton-associated forms of NF proteins during axonal neuritogenesis in cultured dorsal root ganglion (DRG) neurons and NB2a/d1 neuroblastoma. In addition to filamentous immunoreactivity, we observed punctate NF immunoreactivity throughout perikarya and neurites. Immuno-electron microscopy revealed this punctate immunoreactivity to consist of non-membrane-bound 75 nm round/ovoid structures consisting of amorphous, fibrous material. Endogenous and microinjected NF subunits incorporated into dots prior to their accumulation within filaments. A transfected GFP-conjugated NF-M incorporated into dots and translocated at a rate consistent with slow axonal transport in real-time video analyses. Some dots converted into a filamentous form or exuded filamentous material during transport. Dots contained conventional kinesin immunoreactivity, associated with microtubules, and their transport into axons was blocked by anti-kinesin antibodies and nocodazole. These oligomeric structures apparently represent one form in which NF subunits are transported in growing axons and may utilize kinesin as a transport motor.
Yabe
J T
JT
Center for Cellular Neurobiology and Neurodegeneration Research, Department of Biological Sciences, University of Massachusetts at Lowell, One University Avenue, Lowell, MA 01854, USA.
Pimenta
A
A
Shea
T B
TB
D000818:Animals; D001370:Axonal Transport / Q000502:physiology; D001369:Axons / Q000378:metabolism* / Q000502:physiology*; D018929:Cell Culture Techniques; D002642:Chick Embryo; D005727:Ganglia, Spinal / Q000378:metabolism; D016547:Kinesins / Q000378:metabolism* / Q000502:physiology*; D008870:Microtubules / Q000378:metabolism / Q000502:physiology; D020409:Molecular Motor Proteins / Q000378:metabolism / Q000502:physiology; D009447:Neuroblastoma; D016900:Neurofilament Proteins / Q000378:metabolism* / Q000502:physiology*
D020409:Molecular Motor Proteins; D016900:Neurofilament Proteins; D016547:Kinesins