Exportins can inhibit major mitotic assembly events in vitro: membrane fusion, nuclear pore formation, and spindle assembly. Issue 1 (1st January 2020)

• Record Type: Journal Article
• Authors: Nord, Matthew S.; Bernis, Cyril; Carmona, Sarah; Garland, Dennis C.; Travesa, Anna; Forbes, Douglass J.
• Is Part Of: Nucleus. Volume 11: Issue 1(2020)
• Page Start: 178
• Page End: 193
• Publication Date: 2020-01-01
• Subjects: Exportins -- cell cycle -- ranGTP -- nuclear pore -- spindle -- assembly -- nucleoporin -- importins -- karyopherins -- Crm1; Cell nuclei -- Periodicals; Biology -- Periodicals; Biology; Cell nuclei; Periodicals; 571.6605
• DOI: 10.1080/19491034.2020.1798093
• Languages: English
• ISSNs: 1949-1034

Abstract

ABSTRACT: 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.