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Nup2 requires a highly divergent partner, NupA, to fulfill functions at nuclear pore complexes and the mitotic chromatin region.

Markossian S, Suresh S, Osmani AH, Osmani SA - Mol. Biol. Cell (2014)

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.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Gene Regulation and Development, National Institute for Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892.

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Related in: MedlinePlus

NupA localizes like Nup2 to NPCs during interphase and to the chromatin region during mitosis. (A) Images and kymograph from time-lapse microscopy (strain SM86) monitoring NupA-GFP and NLS-DsRed. NupA-GFP locates to the chromatin region during mitosis (M) as NLS-DsRed disperses from the mitotic nucleus when NPCs are partially disassembled. During exit from mitosis, NupA relocates back to NPCs as nuclear transport is reestablished. (B) NupA-GFP and Histone H1-mRFP in strain SM122 during G2, mitosis (M), and G1. Also shown are a merged image and pixel profiles for both signals through the dividing nucleus. (C) NupA-GFP and Nup2-ChRFP in strain SM88 during G2, mitosis (M), and G1. Also shown are a merged image and pixel profiles for both signals through the dividing nucleus. (D) Cartoon of the location of Nup2 and NupA (red) during mitotic phases. (E) Sequential z-stack confocal images of Nup2-GFP and NupA-GFP in combination with Histone H1-mRFP in metaphase and anaphase/telophase as indicated (strains SO572 and SM124, respectively). Nuclei that had just exited metaphase and had their DNA still condensed were classified as anaphase–telophase. Nup2 and NupA move from throughout the chromatin region to around segregating chromatin after anaphase. Bar, ∼5 μm.
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Figure 4: NupA localizes like Nup2 to NPCs during interphase and to the chromatin region during mitosis. (A) Images and kymograph from time-lapse microscopy (strain SM86) monitoring NupA-GFP and NLS-DsRed. NupA-GFP locates to the chromatin region during mitosis (M) as NLS-DsRed disperses from the mitotic nucleus when NPCs are partially disassembled. During exit from mitosis, NupA relocates back to NPCs as nuclear transport is reestablished. (B) NupA-GFP and Histone H1-mRFP in strain SM122 during G2, mitosis (M), and G1. Also shown are a merged image and pixel profiles for both signals through the dividing nucleus. (C) NupA-GFP and Nup2-ChRFP in strain SM88 during G2, mitosis (M), and G1. Also shown are a merged image and pixel profiles for both signals through the dividing nucleus. (D) Cartoon of the location of Nup2 and NupA (red) during mitotic phases. (E) Sequential z-stack confocal images of Nup2-GFP and NupA-GFP in combination with Histone H1-mRFP in metaphase and anaphase/telophase as indicated (strains SO572 and SM124, respectively). Nuclei that had just exited metaphase and had their DNA still condensed were classified as anaphase–telophase. Nup2 and NupA move from throughout the chromatin region to around segregating chromatin after anaphase. Bar, ∼5 μm.

Mentions: As mentioned above, during A. nidulans mitosis, NPCs partially disassemble, and nuclear proteins, such as NLS-DsRed, disperse from nuclei and locate throughout the cell (De Souza et al., 2004; Osmani et al., 2006a; De Souza and Osmani, 2009). Dispersal of NLS-DsRed therefore acts as a marker for entry into mitosis and its nuclear reimport a marker for mitotic exit into G1. In a manner identical to Nup2, NupA-GFP was found to translocate from NPCs to concentrate to the mitotic chromatin region until cells exit mitosis (Figure 4A). Accordingly, NupA-GFP and the chromatin marker histone H1–monomeric red fluorescent protein (mRFP) localized together during mitosis (Figure 4B), and, as expected from their copurification, NupA-GFP and Nup2-ChRFP localize together at interphase NPCs and the mitotic chromatin region (Figure 4C).


Nup2 requires a highly divergent partner, NupA, to fulfill functions at nuclear pore complexes and the mitotic chromatin region.

Markossian S, Suresh S, Osmani AH, Osmani SA - Mol. Biol. Cell (2014)

NupA localizes like Nup2 to NPCs during interphase and to the chromatin region during mitosis. (A) Images and kymograph from time-lapse microscopy (strain SM86) monitoring NupA-GFP and NLS-DsRed. NupA-GFP locates to the chromatin region during mitosis (M) as NLS-DsRed disperses from the mitotic nucleus when NPCs are partially disassembled. During exit from mitosis, NupA relocates back to NPCs as nuclear transport is reestablished. (B) NupA-GFP and Histone H1-mRFP in strain SM122 during G2, mitosis (M), and G1. Also shown are a merged image and pixel profiles for both signals through the dividing nucleus. (C) NupA-GFP and Nup2-ChRFP in strain SM88 during G2, mitosis (M), and G1. Also shown are a merged image and pixel profiles for both signals through the dividing nucleus. (D) Cartoon of the location of Nup2 and NupA (red) during mitotic phases. (E) Sequential z-stack confocal images of Nup2-GFP and NupA-GFP in combination with Histone H1-mRFP in metaphase and anaphase/telophase as indicated (strains SO572 and SM124, respectively). Nuclei that had just exited metaphase and had their DNA still condensed were classified as anaphase–telophase. Nup2 and NupA move from throughout the chromatin region to around segregating chromatin after anaphase. Bar, ∼5 μm.
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Related In: Results  -  Collection

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Figure 4: NupA localizes like Nup2 to NPCs during interphase and to the chromatin region during mitosis. (A) Images and kymograph from time-lapse microscopy (strain SM86) monitoring NupA-GFP and NLS-DsRed. NupA-GFP locates to the chromatin region during mitosis (M) as NLS-DsRed disperses from the mitotic nucleus when NPCs are partially disassembled. During exit from mitosis, NupA relocates back to NPCs as nuclear transport is reestablished. (B) NupA-GFP and Histone H1-mRFP in strain SM122 during G2, mitosis (M), and G1. Also shown are a merged image and pixel profiles for both signals through the dividing nucleus. (C) NupA-GFP and Nup2-ChRFP in strain SM88 during G2, mitosis (M), and G1. Also shown are a merged image and pixel profiles for both signals through the dividing nucleus. (D) Cartoon of the location of Nup2 and NupA (red) during mitotic phases. (E) Sequential z-stack confocal images of Nup2-GFP and NupA-GFP in combination with Histone H1-mRFP in metaphase and anaphase/telophase as indicated (strains SO572 and SM124, respectively). Nuclei that had just exited metaphase and had their DNA still condensed were classified as anaphase–telophase. Nup2 and NupA move from throughout the chromatin region to around segregating chromatin after anaphase. Bar, ∼5 μm.
Mentions: As mentioned above, during A. nidulans mitosis, NPCs partially disassemble, and nuclear proteins, such as NLS-DsRed, disperse from nuclei and locate throughout the cell (De Souza et al., 2004; Osmani et al., 2006a; De Souza and Osmani, 2009). Dispersal of NLS-DsRed therefore acts as a marker for entry into mitosis and its nuclear reimport a marker for mitotic exit into G1. In a manner identical to Nup2, NupA-GFP was found to translocate from NPCs to concentrate to the mitotic chromatin region until cells exit mitosis (Figure 4A). Accordingly, NupA-GFP and the chromatin marker histone H1–monomeric red fluorescent protein (mRFP) localized together during mitosis (Figure 4B), and, as expected from their copurification, NupA-GFP and Nup2-ChRFP localize together at interphase NPCs and the mitotic chromatin region (Figure 4C).

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.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Gene Regulation and Development, National Institute for Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892.

Show MeSH
Related in: MedlinePlus