TY - JOUR
T1 - Microtubule reorganization is obligatory for growth cone turning
AU - Williamson, Toni
AU - Gordon-Weeks, Phillip R.
AU - Schachner, Melitta
AU - Taylor, Joanne
PY - 1996/12/24
Y1 - 1996/12/24
N2 - To examine the role of microtubules in growth cone turning, we have compared the microtubule organization in growth cones advancing on uniform laminin substrates with their organization in growth cones turning at a laminin-tenascin border. The majority (82%) of growth cones on laminin had a symmetrical microtubule organization, in which the microtubules entering the growth cone splay out toward the periphery of the growth cone. Growth cones at tenascin borders had symmetrically arranged microtubules in only 34% of cases, whereas in the majority of cases the microtubules were displaced toward one-half of the growth cone, presumably stabilizing in the direction of the turn along the tenascin border. These results suggest that reorganization of microtubules could underlie growth cone turning. Further evidence for the involvement of microtubule rearrangement in growth cone turning was provided by experiments in which growth cones approached tenascin borders in the presence of nanomolar concentrations of the microtubule stabilizing compound, Taxol. Taxol altered the organization of microtubules in growth cones growing on laminin by restricting their distribution to the proximal regions of the growth cone and increasing their bundling. Taxol did not stop growth cone advance on laminin. When growing in the presence of Taxol, growth cones at tenascin borders were not able to turn and grow along the laminin-tenascin border, and consequently stopped at the border. Growth cones were arrested at borders for as long as Taxol was present (up to 6 h) without showing any signs of drug toxicity. These effects of Taxol were reversible. Together, these results suggest that microtubule reorganization in growth cones is a necessary event in growth cone turning.
AB - To examine the role of microtubules in growth cone turning, we have compared the microtubule organization in growth cones advancing on uniform laminin substrates with their organization in growth cones turning at a laminin-tenascin border. The majority (82%) of growth cones on laminin had a symmetrical microtubule organization, in which the microtubules entering the growth cone splay out toward the periphery of the growth cone. Growth cones at tenascin borders had symmetrically arranged microtubules in only 34% of cases, whereas in the majority of cases the microtubules were displaced toward one-half of the growth cone, presumably stabilizing in the direction of the turn along the tenascin border. These results suggest that reorganization of microtubules could underlie growth cone turning. Further evidence for the involvement of microtubule rearrangement in growth cone turning was provided by experiments in which growth cones approached tenascin borders in the presence of nanomolar concentrations of the microtubule stabilizing compound, Taxol. Taxol altered the organization of microtubules in growth cones growing on laminin by restricting their distribution to the proximal regions of the growth cone and increasing their bundling. Taxol did not stop growth cone advance on laminin. When growing in the presence of Taxol, growth cones at tenascin borders were not able to turn and grow along the laminin-tenascin border, and consequently stopped at the border. Growth cones were arrested at borders for as long as Taxol was present (up to 6 h) without showing any signs of drug toxicity. These effects of Taxol were reversible. Together, these results suggest that microtubule reorganization in growth cones is a necessary event in growth cone turning.
KW - Taxol
KW - axonal pathfinding
KW - tenascin
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U2 - 10.1073/pnas.93.26.15221
DO - 10.1073/pnas.93.26.15221
M3 - Article
C2 - 8986791
AN - SCOPUS:0030461627
SN - 0027-8424
VL - 93
SP - 15221
EP - 15226
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 26
ER -