TY - JOUR
T1 - Ran-dependent docking of importin β- to RanBP2/Nup358 filaments is essential for protein import and cell viability
AU - Hamada, Masakazu
AU - Haeger, Anna
AU - Jeganathan, Karthik B.
AU - van Ree, Janine H.
AU - Malureanu, Liviu
AU - Wälde, Sarah
AU - Joseph, Jomon
AU - Kehlenbach, Ralph H.
AU - van Deursen, Jan M.
PY - 2011/8/22
Y1 - 2011/8/22
N2 - 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.
AB - 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.
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U2 - 10.1083/jcb.201102018
DO - 10.1083/jcb.201102018
M3 - Article
C2 - 21859863
AN - SCOPUS:80052614266
SN - 0021-9525
VL - 194
SP - 597
EP - 612
JO - Journal of Cell Biology
JF - Journal of Cell Biology
IS - 4
ER -