title: The interaction of neurofilaments with the microtubule motor cytoplasmic dynein.
abstract: Neurofilaments are synthesized in the cell body of neurons and transported outward along the axon via slow axonal transport. Direct observation of neurofilaments trafficking in live cells suggests that the slow outward rate of transport is due to the net effects of anterograde and retrograde microtubule motors pulling in opposition. Previous studies have suggested that cytoplasmic dynein is required for efficient neurofilament transport. In this study, we examine the interaction of neurofilaments with cytoplasmic dynein. We used fluid tapping mode atomic force microscopy to visualize single neurofilaments, microtubules, dynein/dynactin, and physical interactions between these neuronal components. AFM images suggest that neurofilaments act as cargo for dynein, associating with the base of the motor complex. Yeast two-hybrid and affinity chromatography assays confirm this hypothesis, indicating that neurofilament subunit M binds directly to dynein IC. This interaction is blocked by monoclonal antibodies directed either to NF-M or to dynein. Together these data suggest that a specific interaction between neurofilament subunit M and cytoplasmic dynein is involved in the saltatory bidirectional motility of neurofilaments undergoing axonal transport in the neuron.
authors.affiliation: Institute of Medicine and Engineering, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6085, USA.
authors.forename: Oliver I
authors.initials: OI
authors.lastname: Wagner
authors.forename: Jennifer
authors.initials: J
authors.lastname: Ascaño
authors.forename: Mariko
authors.initials: M
authors.lastname: Tokito
authors.forename: Jean-Francois
authors.initials: JF
authors.lastname: Leterrier
authors.forename: Paul A
authors.initials: PA
authors.lastname: Janmey
authors.forename: Erika L F
authors.initials: EL
authors.lastname: Holzbaur
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism; D002417:Cattle; D002846:Chromatography, Affinity; D003593:Cytoplasm / Q000378:metabolism*; D000072159:Dynactin Complex; D004398:Dyneins / Q000737:chemistry*; D018625:Microscopy, Atomic Force; D008854:Microscopy, Electron; D008869:Microtubule-Associated Proteins / Q000737:chemistry; D008870:Microtubules / Q000378:metabolism*; D016900:Neurofilament Proteins / Q000737:chemistry*; D009474:Neurons / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D051381:Rats; D013116:Spinal Cord / Q000378:metabolism; D020798:Two-Hybrid System Techniques
chemical_list: D000072159:Dynactin Complex; D008869:Microtubule-Associated Proteins; D016900:Neurofilament Proteins; D004398:Dyneins