Microtubule polymer assembly and transport during axonal elongation.

1991/10/15 by Sigrid Reinsch, Timothy J. Mitchison, Marc W. Kirschner · 1 voice · 164 citations
Biochemistry, Genetics and Molecular Biology · #14-3-3 protein interactions #Axon #Axon guidance #Axoplasmic transport #Biology #Biophysics #Cell biology #Elongation #Growth cone #Materials science #Microtubule #Microtubule and mitosis dynamics #Photosynthetic Processes and Mechanisms #Tubulin

paper · pdf · doi:10.1083/jcb.115.2.365

published in The Journal of Cell Biology 115(2), 365-379 (Rockefeller University Press)

openalex publication_date 1991/10/15 · openalex created_date 2025/10/10 · openalex updated_date 2026/06/26

Abstract

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.

Cited by

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• Newly assembled microtubules are concentrated in the proximal and distal regions of growing axons. [europepmc]
• The emerging role of forces in axonal elongation. [europepmc]
• Identification of differentially expressed genes in SHSY5Y cells exposed to okadaic acid by suppression subtractive hybridization. [europepmc]
• Initial neurite outgrowth in Drosophila neurons is driven by kinesin-powered microtubule sliding. [europepmc]
• Okadaic acid: more than a diarrheic toxin. [europepmc]
• Drosophila growth cones advance by forward translocation of the neuronal cytoskeletal meshwork in vivo. [europepmc]
• Moonlighting Motors: Kinesin, Dynein, and Cell Polarity. [europepmc]
• An Integrated Cytoskeletal Model of Neurite Outgrowth. [europepmc]
• The model of local axon homeostasis - explaining the role and regulation of microtubule bundles in axon maintenance and pathology. [europepmc]
• Patterning Microtubule Network Organization Reshapes Cell-Like Compartments. [europepmc]
• The role of mechanics in axonal stability and development. [europepmc]
• A simple active fluid model unites cytokinesis, cell crawling, and axonal outgrowth. [europepmc]
• Functional analysis of dynactin and cytoplasmic dynein in slow axonal transport. [europepmc]
• Microtubule transport from the cell body into the axons of growing neurons. [europepmc]
• Transport and turnover of microtubules in frog neurons depend on the pattern of axonal growth. [europepmc]

Discussions

• Xenopus embryo growth cones move at 100-120 µm/hour 🏎️ doi.org/10.1083/jcb.... Scale bar below if 10 µm and total time is 11 minutes.That's about 2 times the speed of the fastest cell in the 2013 Ce [bsky, 29 points, 1 comments]

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