mRNA export from mammalian cell nuclei is dependent on GANP.
Bulk nuclear export of messenger ribonucleoproteins (mRNPs) through nuclear pore complexes (NPCs) is mediated by NXF1. It binds mRNPs through adaptor proteins such as ALY and SR splicing factors and mediates translocation through the central NPC transport channel via transient interactions with FG nucleoporins. Here, we show that mammalian cells require GANP (germinal center-associated nuclear protein) for efficient mRNP nuclear export and for efficient recruitment of NXF1 to NPCs. Separate regions of GANP show local homology to FG nucleoporins, the yeast mRNA export factor Sac3p, and the mammalian MCM3 acetyltransferase. GANP interacts with both NXF1 and NPCs and partitions between NPCs and the nuclear interior. GANP depletion inhibits mRNA export, with retention of mRNPs and NXF1 in punctate foci within the nucleus. The GANP N-terminal region that contains FG motifs interacts with the NXF1 FG-binding domain. Overexpression of this GANP fragment leads to nuclear accumulation of both poly(A)(+)RNA and NXF1. Treatment with transcription inhibitors redistributes GANP from NPCs into foci throughout the nucleus. These results establish GANP as an integral component of the mammalian mRNA export machinery and suggest a model whereby GANP facilitates the transfer of NXF1-containing mRNPs to NPCs.
Wickramasinghe
Vihandha O
VO
MRC Cancer Cell Unit, Hutchison/MRC Research Centre, Hills Road, Cambridge CB2 0XZ, UK. vw222@hutchison-mrc.cam.ac.uk
McMurtrie
Paul I A
PI
Mills
Anthony D
AD
Takei
Yoshinori
Y
Penrhyn-Lowe
Sue
S
Amagase
Yoko
Y
Main
Sarah
S
Marr
Jackie
J
Stewart
Murray
M
Laskey
Ronald A
RA
D000123:Acetyltransferases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D021581:Active Transport, Cell Nucleus; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D018858:Germinal Center / Q000378:metabolism*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008322:Mammals; D008954:Models, Biological; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D029543:Nucleocytoplasmic Transport Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D010750:Phosphoproteins / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D016601:RNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D012261:Ribonucleoproteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
C481510:GANP protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; C122111:NXF1 protein, human; D009687:Nuclear Proteins; D029543:Nucleocytoplasmic Transport Proteins; D010750:Phosphoproteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins; C026452:messenger ribonucleoprotein; D000123:Acetyltransferases; C406825:MCM3AP protein, human