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J Cell Biol. 2019 Aug 2. pii: jcb.201901127. doi: 10.1083/jcb.201901127. [Epub ahead of print]

Imaging within single NPCs reveals NXF1's role in mRNA export on the cytoplasmic side of the pore.

Author information

1
The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel.
2
Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan, Israel.
3
Department of Physics, Bar-Ilan University, Ramat Gan, Israel.
4
The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel yaron.shav-tal@biu.ac.il.

Abstract

Translocation of mRNA through the nuclear pore complex (NPC) requires interactions with different NPC regions. To determine the interactions that are crucial for effective mRNA export in living cells, we examined mRNA export within individual pores by applying various types of mRNA export blocks that stalled mRNPs at different stages of transition. Focusing on the major mRNA export factor NXF1, we found that initial mRNP binding to the NPC did not require NXF1 in the NPC, whereas release into the cytoplasm did. NXF1 localization in the NPC did not require RNA or RNA binding. Superresolution microscopy showed that NXF1 consistently occupied positions on the cytoplasmic side of the NPC. Interactions with specific nucleoporins were pinpointed using FLIM-FRET for measuring protein-protein interactions inside single NPCs, showing that Dbp5 helicase activity of mRNA release is conserved in yeast and humans. Altogether, we find that specific interactions on the cytoplasmic side of the NPC are fundamental for the directional flow of mRNA export.

PMID:
31375530
DOI:
10.1083/jcb.201901127

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