Nuclear reformation after mitosis requires downregulation of the Ran GTPase effector RanBP1 in mammalian cells.
The GTPase Ran regulates nucleocytoplasmic transport in interphase and spindle organisation in mitosis via effectors of the importin beta superfamily. Ran-binding protein 1 (RanBP1) regulates guanine nucleotide turnover on Ran, as well as its interactions with effectors. Unlike other Ran network members that are steadily expressed, RanBP1 abundance is modulated during the mammalian cell cycle, peaking in mitosis and declining at mitotic exit. Here, we show that RanBP1 downregulation takes place in mid to late telophase, concomitant with the reformation of nuclei. Mild RanBP1 overexpression in murine cells causes RanBP1 to persist in late mitosis and hinders a set of events underlying the telophase to interphase transition, including chromatin decondensation, nuclear expansion and nuclear lamina reorganisation. Moreover, the reorganisation of nuclear pores fails associated with defective nuclear relocalisation of NLS cargoes. Co-expression of importin beta, together with RanBP1, however mitigates these defects. Thus, RanBP1 downregulation is required for nuclear reorganisation pathways operated by importin beta after mitosis.
Ciciarello
Marilena
M
CNR National Research Council, Institute of Molecular Biology and Pathology, c/o Sapienza University of Rome, Rome, 00185, Italy.
Roscioli
Emanuele
E
Di Fiore
Barbara
B
Di Francesco
Laura
L
Sobrero
Fabrizia
F
Bernard
Delphine
D
Mangiacasale
Rosamaria
R
Harel
Amnon
A
Schininà
Maria Eugenia
ME
Lavia
Patrizia
P
D000818:Animals; D002460:Cell Line; D002467:Cell Nucleus / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D015536:Down-Regulation; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D008938:Mitosis; D041681:NIH 3T3 Cells; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D020931:ran GTP-Binding Protein / Q000235:genetics / Q000378:metabolism*
D009687:Nuclear Proteins; C091775:ran-binding protein 1; D020931:ran GTP-Binding Protein