The Journal of Cell Biology, Vol 115, 365-379, Copyright © 1991 by The Rockefeller University Press

ARTICLES

Microtubule polymer assembly and transport during axonal elongation

SS Reinsch, TJ Mitchison and M Kirschner
Department of Biochemistry and Biophysics, University of California, San Francisco 94143.

As axons elongate, tubulin, which is synthesized in the cell body, must be transported and assembled into new structures in the axon. The mechanism of transport and the location of assembly are presently unknown. We report here on the use of tubulin tagged with a photoactivatable fluorescent group to investigate these issues. Photoactivatable tubulin, microinjected into frog embryos at the two- cell stage, is incorporated into microtubules in neurons obtained from explants of the neural tube. When activated by light, a fluorescent mark is made on the microtubules in the axon, and transport and turnover can be visualized directly. We find that microtubules are generated in or near the cell body and continually transported distally as a coherent phase of polymer during axon elongation. This vectorial polymer movement was observed at all levels on the axon, even in the absence of axonal elongation. Measurements of the rate of polymer translocation at various places in the axon suggest that new polymer is formed by intercalary assembly along the axon and assembly at the growth cone in addition to transport of polymer from the cell body. Finally, polymer movement near the growth cone appeared to respond in a characteristic manner to growth cone behavior, while polymer proximally in the axon moved more consistently. These results suggest that microtubule translocation is the principal means of tubulin transport and that translocation plays an important role in generating new axon structure at the growth cone.
CiteULike    Complore    Connotea    Del.icio.us    Digg    Facebook    Reddit    Technorati    Twitter    What's this?

This article has been cited by other articles:

• Miller, K. E., Sheetz, M. P. (2006). Direct evidence for coherent low velocity axonal transport of mitochondria. JCB 173: 373-381 [Abstract] [Full Text]  
• Wang, L., Brown, A. (2001). Rapid Intermittent Movement of Axonal Neurofilaments Observed by Fluorescence Photobleaching. Mol. Biol. Cell 12: 3257-3267 [Abstract] [Full Text]  
• Ackerley, S., Grierson, A. J., Brownlees, J., Thornhill, P., Anderton, B. H., Leigh, P. N., Shaw, C. E., Miller, C. C.J. (2000). Glutamate Slows Axonal Transport of Neurofilaments in Transfected Neurons. JCB 150: 165-176 [Abstract] [Full Text]  
• Gallo, G., Letourneau, P. C. (1999). Different Contributions of Microtubule Dynamics and Transport to the Growth of Axons and Collateral Sprouts. J. Neurosci. 19: 3860-3873 [Abstract] [Full Text]  
• Koehnle, T. J., Brown, A. (1999). Slow Axonal Transport of Neurofilament Protein in Cultured Neurons. JCB 144: 447-458 [Abstract] [Full Text]  
• Vorobjev, I., Rodionov, V., Maly, I., Borisy, G. (1999). Contribution of plus and minus end pathways to microtubule turnover. J. Cell Sci. 112: 2277-2289 [Abstract]  
• Zakharenko, S., Popov, S. (1998). Dynamics of Axonal Microtubules Regulate the Topology of New Membrane Insertion into the Growing Neurites. JCB 143: 1077-1086 [Abstract] [Full Text]  
• Chang, S., Rodionov, V. I., Borisy, G. G., Popov, S. V. (1998). Transport and Turnover of Microtubules in Frog Neurons Depend on the Pattern of Axonal Growth. J. Neurosci. 18: 821-829 [Abstract] [Full Text]  
• Slaughter, T., Wang, J., Black, M. M. (1997). Microtubule Transport from the Cell Body into the Axons of Growing Neurons. J. Neurosci. 17: 5807-5819 [Abstract] [Full Text]  
• Dillman III, J. F., Dabney, L. P., Karki, S., Paschal, B. M., Holzbaur, E. L. F., Pfister, K. K. (1996). Functional Analysis of Dynactin and Cytoplasmic Dynein in Slow Axonal Transport. J. Neurosci. 16: 6742-6752 [Abstract] [Full Text]  
• Challacombe, J., Snow, D., Letourneau, P. (1996). Actin filament bundles are required for microtubule reorientation during growth cone turning to avoid an inhibitory guidance cue. J. Cell Sci. 109: 2031-2040 [Abstract]  
• Hoffman, P. N. (1995). Review : The Synthesis, Axonal Transport, and Phosphorylation of Neurofilaments Determine Axonal Caliber in Myelinated Nerve Fibers. Neuroscientist 1: 76-83 [Abstract]  
• Zhu, J, Bloom, S., Lazarides, E, Woods, C (1995). Identification of a novel Ca(2+)-regulated protein that is associated with the marginal band and centrosomes of chicken erythrocytes. J. Cell Sci. 108: 685-698 [Abstract]  
• Paturle-Lafanechere, L, Manier, M, Trigault, N, Pirollet, F, Mazarguil, H, Job, D (1994). Accumulation of delta 2-tubulin, a major tubulin variant that cannot be tyrosinated, in neuronal tissues and in stable microtubule assemblies. J. Cell Sci. 107: 1529-1543 [Abstract]  
• Baas, P., Pienkowski, T., Cimbalnik, K., Toyama, K, Bakalis, S, Ahmad, F., Kosik, K. (1994). Tau confers drug stability but not cold stability to microtubules in living cells. J. Cell Sci. 107: 135-143 [Abstract]  
• Popov, S, Brown, A, Poo, M. (1993). Forward plasma membrane flow in growing nerve processes. Science 259: 244-246 [Abstract]  
• Zheng, J, Buxbaum, R., Heidemann, S. (1993). Investigation of microtubule assembly and organization accompanying tension-induced neurite initiation. J. Cell Sci. 104: 1239-1250 [Abstract]  
• Morris, R., Hollenbeck, P. (1993). The regulation of bidirectional mitochondrial transport is coordinated with axonal outgrowth. J. Cell Sci. 104: 917-927 [Abstract]  
• Lafont, F, Rouget, M, Rousselet, A, Valenza, C, Prochiantz, A (1993). Specific responses of axons and dendrites to cytoskeleton perturbations: an in vitro study. J. Cell Sci. 104: 433-443 [Abstract]  

Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents