@article{9414,
  abstract     = {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.},
  author       = {Ishihara, Keisuke and Decker, Franziska and Dos Santos Caldas, Paulo R and Pelletier, James F. and Loose, Martin and Brugués, Jan and Mitchison, Timothy J.},
  issn         = {1939-4586},
  journal      = {Molecular Biology of the Cell},
  number       = {9},
  pages        = {869--879},
  publisher    = {American Society for Cell Biology},
  title        = {{Spatial variation of microtubule depolymerization in large asters}},
  doi          = {10.1091/MBC.E20-11-0723},
  volume       = {32},
  year         = {2021},
}

@article{11082,
  abstract     = {The nuclear pore complex (NPC) plays a critical role in gene expression by mediating import of transcription regulators into the nucleus and export of RNA transcripts to the cytoplasm. Emerging evidence suggests that in addition to mediating transport, a subset of nucleoporins (Nups) engage in transcriptional activation and elongation at genomic loci that are not associated with NPCs. The underlying mechanism and regulation of Nup mobility on and off nuclear pores remain unclear. Here we show that Nup50 is a mobile Nup with a pronounced presence both at the NPC and in the nucleoplasm that can move between these different localizations. Strikingly, the dynamic behavior of Nup50 in both locations is dependent on active transcription by RNA polymerase II and requires the N-terminal half of the protein, which contains importin α– and Nup153-binding domains. However, Nup50 dynamics are independent of importin α, Nup153, and Nup98, even though the latter two proteins also exhibit transcription-dependent mobility. Of interest, depletion of Nup50 from C2C12 myoblasts does not affect cell proliferation but inhibits differentiation into myotubes. Taken together, our results suggest a transport-independent role for Nup50 in chromatin biology that occurs away from the NPC.},
  author       = {Buchwalter, Abigail L. and Liang, Yun and HETZER, Martin W},
  issn         = {1059-1524},
  journal      = {Molecular Biology of the Cell},
  keywords     = {Cell Biology, Molecular Biology},
  number       = {16},
  pages        = {2472--2484},
  publisher    = {American Society for Cell Biology},
  title        = {{Nup50 is required for cell differentiation and exhibits transcription-dependent dynamics}},
  doi          = {10.1091/mbc.e14-04-0865},
  volume       = {25},
  year         = {2014},
}