Premium
Ran GTP and importin β regulate meiosis I spindle assembly and function in mouse oocytes
Author(s) -
Drutovic David,
Duan Xing,
Li Rong,
Kalab Petr,
Solc Petr
Publication year - 2019
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.15252/embj.2019101689
Subject(s) - czech , whiting , library science , biology , computer science , fish <actinopterygii> , philosophy , linguistics , fishery
Homologous chromosome segregation during meiosis I ( MI ) in mammalian oocytes is carried out by the acentrosomal MI spindles. Whereas studies in human oocytes identified Ran GTP ase as a crucial regulator of the MI spindle function, experiments in mouse oocytes questioned the generality of this notion. Here, we use live‐cell imaging with fluorescent probes and Förster resonance energy transfer ( FRET ) biosensors to monitor the changes in Ran and importin β signaling induced by perturbations of Ran in mouse oocytes while examining the MI spindle dynamics. We show that unlike RanT24N employed in previous studies, a RanT24N, T42A double mutant inhibits Ran GEF without perturbing cargo binding to importin β and disrupts MI spindle function in chromosome segregation. Roles of Ran and importin β in the coalescence of microtubule organizing centers ( MTOC s) and MI spindle assembly are further supported by the use of the chemical inhibitor importazole, whose effects are partially rescued by the GTP hydrolysis‐resistant RanQ69L mutant. These results indicate that Ran GTP is essential for MI spindle assembly and function both in humans and mice.