Ran-dependent docking of importin β- to RanBP2/Nup358 filaments is essential for protein import and cell viability

Masakazu Hamada, Anna Haeger, Karthik B. Jeganathan, Janine H. van Ree, Liviu Malureanu, Sarah Wälde, Jomon Joseph, Ralph H. Kehlenbach, Jan M. van Deursen

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Abstract

RanBP2/Nup358, the major component of the cytoplasmic filaments of the nuclear pore complex (NPC), is essential for mouse embryogenesis and is implicated in both macromolecular transport and mitosis, but its specific molecular functions are unknown. Using RanBP2 conditional knockout mouse embryonic fibroblasts and a series of mutant constructs, we show that transport, rather than mitotic, functions of RanBP2 are required for cell viability. Cre-mediated RanBP2 inactivation caused cell death with defects in M9- and classical nuclear localization signal (cNLS)-mediated protein import, nuclear export signal-mediated protein export, and messenger ribonucleic acid export but no apparent mitotic failure. A short N-terminal RanBP2 fragment harboring the NPCbinding domain, three phenylalanine-glycine motifs, and one Ran-binding domain (RBD) corrected all transport defects and restored viability. Mutation of the RBD within this fragment caused lethality and perturbed binding to Ran guanosine triphosphate (GTP)-importin-β, accumulation of importin-β at nuclear pores, and cNLS-mediated protein import. These data suggest that a critical function of RanBP2 is to capture recycling RanGTP-importin-β complexes at cytoplasmic fibrils to allow for adequate cNLS-mediated cargo import.

Original languageEnglish (US)
Pages (from-to)597-612
Number of pages16
JournalJournal of Cell Biology
Volume194
Issue number4
DOIs
StatePublished - Aug 22 2011

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ASJC Scopus subject areas

  • Cell Biology

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Hamada, M., Haeger, A., Jeganathan, K. B., van Ree, J. H., Malureanu, L., Wälde, S., Joseph, J., Kehlenbach, R. H., & van Deursen, J. M. (2011). Ran-dependent docking of importin β- to RanBP2/Nup358 filaments is essential for protein import and cell viability. Journal of Cell Biology, 194(4), 597-612. https://doi.org/10.1083/jcb.201102018