article published yes Keisuke Ishihara author Franziska Decker author Paulo R Dos Santos Caldas author 38FCDB4C-F248-11E8-B48F-1D18A9856A870000-0001-6730-4461 James F. Pelletier author Martin Loose author 462D4284-F248-11E8-B48F-1D18A9856A870000-0001-7309-9724 Jan Brugués author Timothy J. Mitchison author MaLo department Self-Organization of the Bacterial Cell project Reconstitution of Bacterial Cell Division Using Purified Components project Microtubule plus-end depolymerization rate is a potentially important target of physiological regulation, but it has been challenging to measure, so its role in spatial organization is poorly understood. Here we apply a method for tracking plus ends based on time difference imaging to measure depolymerization rates in large interphase asters growing in Xenopus egg extract. We observed strong spatial regulation of depolymerization rates, which were higher in the aster interior compared with the periphery, and much less regulation of polymerization or catastrophe rates. We interpret these data in terms of a limiting component model, where aster growth results in lower levels of soluble tubulin and microtubule-associated proteins (MAPs) in the interior cytosol compared with that at the periphery. The steady-state polymer fraction of tubulin was ∼30%, so tubulin is not strongly depleted in the aster interior. We propose that the limiting component for microtubule assembly is a MAP that inhibits depolymerization, and that egg asters are tuned to low microtubule density. https://creativecommons.org/licenses/by-nc-sa/3.0/ American Society for Cell Biology2021 eng 1059-1524 1939-4586 33439671 00064157470000510.1091/MBC.E20-11-0723 329869-879 K. Ishihara, F. Decker, P.R. Dos Santos Caldas, J.F. Pelletier, M. Loose, J. Brugués, T.J. Mitchison, Molecular Biology of the Cell 32 (2021) 869–879. Ishihara, K., Decker, F., Dos Santos Caldas, P. R., Pelletier, J. F., Loose, M., Brugués, J., &#38; Mitchison, T. J. (2021). Spatial variation of microtubule depolymerization in large asters. <i>Molecular Biology of the Cell</i>. American Society for Cell Biology. <a href="https://doi.org/10.1091/MBC.E20-11-0723">https://doi.org/10.1091/MBC.E20-11-0723</a> Ishihara, Keisuke, Franziska Decker, Paulo R Dos Santos Caldas, James F. Pelletier, Martin Loose, Jan Brugués, and Timothy J. Mitchison. “Spatial Variation of Microtubule Depolymerization in Large Asters.” <i>Molecular Biology of the Cell</i>. American Society for Cell Biology, 2021. <a href="https://doi.org/10.1091/MBC.E20-11-0723">https://doi.org/10.1091/MBC.E20-11-0723</a>. K. Ishihara <i>et al.</i>, “Spatial variation of microtubule depolymerization in large asters,” <i>Molecular Biology of the Cell</i>, vol. 32, no. 9. American Society for Cell Biology, pp. 869–879, 2021. Ishihara, Keisuke, et al. “Spatial Variation of Microtubule Depolymerization in Large Asters.” <i>Molecular Biology of the Cell</i>, vol. 32, no. 9, American Society for Cell Biology, 2021, pp. 869–79, doi:<a href="https://doi.org/10.1091/MBC.E20-11-0723">10.1091/MBC.E20-11-0723</a>. Ishihara K, Decker F, Dos Santos Caldas PR, et al. Spatial variation of microtubule depolymerization in large asters. <i>Molecular Biology of the Cell</i>. 2021;32(9):869-879. doi:<a href="https://doi.org/10.1091/MBC.E20-11-0723">10.1091/MBC.E20-11-0723</a> Ishihara K, Decker F, Dos Santos Caldas PR, Pelletier JF, Loose M, Brugués J, Mitchison TJ. 2021. Spatial variation of microtubule depolymerization in large asters. Molecular Biology of the Cell. 32(9), 869–879. 94142021-05-23T22:01:45Z2026-06-18T19:52:16Z