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Nucleus January 1, 2020; 11 (1): 178-193.

Exportins can inhibit major mitotic assembly events in vitro: membrane fusion, nuclear pore formation, and spindle assembly.

Nord MS , Bernis C , Carmona S , Garland DC , Travesa A , Forbes DJ .

XENOPUS: egg extracts are a powerful in vitro tool for studying complex biological processes, including nuclear reconstitution, nuclear membrane and pore assembly, and spindle assembly. Extracts have been further used to demonstrate a moonlighting regulatory role for nuclear import receptors or importins on these cell cycle assembly events. Here we show that exportins can also play a role in these events. Addition of Crm1, Exportin-t, or Exportin-5 decreased nuclear pore assembly in vitro. RanQ69L-GTP, a constitutively active form of RanGTP, ameliorated inhibition. Both Crm1 and Exportin-t inhibited fusion of nuclear membranes, again counteracted by RanQ69L-GTP. In mitotic extracts, Crm1 and Exportin-t negatively impacted spindle assembly. Pulldowns from the extracts using Crm1- or Exportin-t-beads revealed nucleoporins known to be essential for both nuclear pore and spindle assembly, with RanQ69L-GTP decreasing a subset of these target interactions. This study suggests a model where exportins, like importins, can regulate major mitotic assembly events.

PubMed ID: 32762441
PMC ID: PMC7540616
Article link: Nucleus
Grant support: [+]

Species referenced: Xenopus laevis
Genes referenced: nup133 nup98 post xpo5 xpot
GO keywords: nuclear pore [+]

Article Images: [+] show captions
References [+] :
Arnaoutov, Crm1 is a mitotic effector of Ran-GTP in somatic cells. 2005, Pubmed