Nup2 requires a highly divergent partner, NupA, to fulfill functions at nuclear pore complexes and the mitotic chromatin region.
Bottom Line: These mitotic problems are not caused by overall defects in mitotic NPC disassembly-reassembly or general nuclear import.However, without Nup2 or NupA, although the SAC protein Mad1 locates to its mitotic locations, it fails to locate to NPCs normally in G1 after mitosis.Collectively the study provides new insight into the roles of Nup2 and NupA during mitosis and in a surveillance mechanism that regulates nucleokinesis when mitotic defects occur after SAC fulfillment.
Affiliation: Laboratory of Gene Regulation and Development, National Institute for Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892.Show MeSH
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Mentions: Although transport of NLS-DsRed does not require Nup2 and NupA, we observed defects in the location of Mad1-GFP to nuclei after mitosis. Mad1-GFP displays distinct sequential cell cycle–regulated locations; NPCs during interphase, at kinetochores and the Mlp1-associated spindle matrix region during mitosis, transiently dispersed from nuclei during exit from mitosis and then briefly in the nucleoplasm before being reassembled back to NPCs in G1 (De Souza et al., 2009; Figure 9A). In the absence of Nup2 or NupA, live-cell imaging revealed that Mad1-GFP located normally at NPCs before mitosis and also transitioned to kinetochores upon entry into mitosis, as expected (Figures 6C and 9A). Also as in wild-type cells, Mad1-GFP dispersed from nuclei during mitotic exit. However, in the absence of Nup2, Mad1-GFP failed to accumulate back into G1 nuclei normally after completion of mitosis (Figure 9A).
Affiliation: Laboratory of Gene Regulation and Development, National Institute for Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892.