RanBP2/Nup358 provides a major binding site for NXF1-p15 dimers at the nuclear pore complex and functions in nuclear mRNA export.
Metazoan NXF1-p15 heterodimers promote the nuclear export of bulk mRNA across nuclear pore complexes (NPCs). In vitro, NXF1-p15 forms a stable complex with the nucleoporin RanBP2/Nup358, a component of the cytoplasmic filaments of the NPC, suggesting a role for this nucleoporin in mRNA export. We show that depletion of RanBP2 from Drosophila cells inhibits proliferation and mRNA export. Concomitantly, the localization of NXF1 at the NPC is strongly reduced and a significant fraction of this normally nuclear protein is detected in the cytoplasm. Under the same conditions, the steady-state subcellular localization of other nuclear or cytoplasmic proteins and CRM1-mediated protein export are not detectably affected, indicating that the release of NXF1 into the cytoplasm and the inhibition of mRNA export are not due to a general defect in NPC function. The specific role of RanBP2 in the recruitment of NXF1 to the NPC is highlighted by the observation that depletion of CAN/Nup214 also inhibits cell proliferation and mRNA export but does not affect NXF1 localization. Our results indicate that RanBP2 provides a major binding site for NXF1 at the cytoplasmic filaments of the NPC, thereby restricting its diffusion in the cytoplasm after NPC translocation. In RanBP2-depleted cells, NXF1 diffuses freely through the cytoplasm. Consequently, the nuclear levels of the protein decrease and export of bulk mRNA is impaired.
Forler
Daniel
D
EMBL, 69117 Heidelberg, Germany.
Rabut
Gwénaël
G
Ciccarelli
Francesca D
FD
Herold
Andrea
A
Köcher
Thomas
T
Niggeweg
Ricarda
R
Bork
Peer
P
Ellenberg
Jan
J
Izaurralde
Elisa
E
D000818:Animals; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase / Q000378:metabolism; D019281:Dimerization; D004331:Drosophila melanogaster / Q000378:metabolism; D006801:Humans; D028884:Karyopherins / Q000378:metabolism; D018832:Molecular Chaperones; D022022:Nuclear Pore / Q000378:metabolism*; D028861:Nuclear Pore Complex Proteins / Q000378:metabolism*; D029543:Nucleocytoplasmic Transport Proteins / Q000378:metabolism*; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000378:metabolism*; D018160:Receptors, Cytoplasmic and Nuclear; D000097606:Exportin 1 Protein
D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D028884:Karyopherins; D018832:Molecular Chaperones; D028861:Nuclear Pore Complex Proteins; D029543:Nucleocytoplasmic Transport Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D018160:Receptors, Cytoplasmic and Nuclear; D000097606:Exportin 1 Protein; C122111:NXF1 protein, human; C406243:RBM8A protein, human; C094493:ran-binding protein 2; C085108:APEX1 protein, human