Limits...
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.

Show MeSH

Related in: MedlinePlus

nup2- and nupA- mutants display defects in mitotic exit. (A) Images captured during live-cell imaging of wild-type (SM116) and (B) nupA- (ΔnupA, from heterokaryon SM127) strains during mitosis, monitoring the INM marker GFP-AN0162 and NLS-DsRed. Without NupA function, the nucleus fails to complete karyokinesis and forms one polyploid nucleus after mitosis. GFP-AN0162 does not locate to the periphery of the nucleolus after anaphase as obviously as the wild type (compare structures at arrows). Pseudocoloring represents false coloring using the thermal color scale of ImageJ. The Fire Color lookup table was applied to grayscale images to produce false-color images (pixels with a value of 0 are white, and pixels with a value of 255 are black). Bar, ∼2.5 μm. (C) Mitosis of a wild type (strain HA375) following spindle and chromatin dynamics of four mitotic nuclei. Bar, ∼5 μm. (D) A mitotic depolyploidization event in a nupA- mutant (from heterokaryon SM98) showing multiple bipolar spindles forming in a polyploid nucleus that remains in an extended metaphase-like state before exiting mitosis. Bar, ∼5 μm. (E) Quantitation of the percentage of larger polyploid nuclei generated in wild-type (strain HA375) compared with nup2- and nupA- cells (heterokaryons SM96 and SM98, respectively).
© Copyright Policy - creative-commons
Related In: Results  -  Collection


getmorefigures.php?uid=PMC4325833&req=5

Figure 7: nup2- and nupA- mutants display defects in mitotic exit. (A) Images captured during live-cell imaging of wild-type (SM116) and (B) nupA- (ΔnupA, from heterokaryon SM127) strains during mitosis, monitoring the INM marker GFP-AN0162 and NLS-DsRed. Without NupA function, the nucleus fails to complete karyokinesis and forms one polyploid nucleus after mitosis. GFP-AN0162 does not locate to the periphery of the nucleolus after anaphase as obviously as the wild type (compare structures at arrows). Pseudocoloring represents false coloring using the thermal color scale of ImageJ. The Fire Color lookup table was applied to grayscale images to produce false-color images (pixels with a value of 0 are white, and pixels with a value of 255 are black). Bar, ∼2.5 μm. (C) Mitosis of a wild type (strain HA375) following spindle and chromatin dynamics of four mitotic nuclei. Bar, ∼5 μm. (D) A mitotic depolyploidization event in a nupA- mutant (from heterokaryon SM98) showing multiple bipolar spindles forming in a polyploid nucleus that remains in an extended metaphase-like state before exiting mitosis. Bar, ∼5 μm. (E) Quantitation of the percentage of larger polyploid nuclei generated in wild-type (strain HA375) compared with nup2- and nupA- cells (heterokaryons SM96 and SM98, respectively).

Mentions: In cells lacking Nup2 or NupA, although the SAC is engaged causing mitotic delay, the cells do not all subsequently complete mitosis normally, even though the SAC is apparently fulfilled to allow progression into anaphase. This was revealed by monitoring formation of daughter nuclei in ΔnupA cells using the inner nuclear membrane (INM) marker AN0162-GFP in combination with NLS-DsRed. AN0162 is an INM marker that contains a C-terminal transmembrane domain and is similar to the Schizosaccharomyces pombe INM protein Bqt4 (unpublished data and annotated at AspGD as AN0162). During karyokinesis, the NE undergoes double restrictions and abscissions to generate daughter nuclei. This process also separates the nucleolus from nuclei (Ukil et al., 2009). Twenty percent of nupA- nuclei displayed defects during mitotic exit, and although two apparently normal G1 nuclei were initially formed, they remain associated via the NE, and karyokinesis failed, resulting in the formation of a single diploid nucleus (Figure 7, B and E). During failed nucleokinesis, AN0162 did not locate correctly around the nucleolus (compare Figure 7, A and B, arrow). Furthermore, after several rounds of mitosis, some mutant polyploid nuclei were seen to form multiple bipolar spindles during mitosis (Figure 7D), indicating that these nuclei were the products of more than one round of defective karyokinesis. Lack of Nup2 or NupA therefore compromises aspects of mitosis that are monitored by the SAC and also perturbs NE dynamics during mitotic exit, which can lead to failed karyokinesis.


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)

nup2- and nupA- mutants display defects in mitotic exit. (A) Images captured during live-cell imaging of wild-type (SM116) and (B) nupA- (ΔnupA, from heterokaryon SM127) strains during mitosis, monitoring the INM marker GFP-AN0162 and NLS-DsRed. Without NupA function, the nucleus fails to complete karyokinesis and forms one polyploid nucleus after mitosis. GFP-AN0162 does not locate to the periphery of the nucleolus after anaphase as obviously as the wild type (compare structures at arrows). Pseudocoloring represents false coloring using the thermal color scale of ImageJ. The Fire Color lookup table was applied to grayscale images to produce false-color images (pixels with a value of 0 are white, and pixels with a value of 255 are black). Bar, ∼2.5 μm. (C) Mitosis of a wild type (strain HA375) following spindle and chromatin dynamics of four mitotic nuclei. Bar, ∼5 μm. (D) A mitotic depolyploidization event in a nupA- mutant (from heterokaryon SM98) showing multiple bipolar spindles forming in a polyploid nucleus that remains in an extended metaphase-like state before exiting mitosis. Bar, ∼5 μm. (E) Quantitation of the percentage of larger polyploid nuclei generated in wild-type (strain HA375) compared with nup2- and nupA- cells (heterokaryons SM96 and SM98, respectively).
© Copyright Policy - creative-commons
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4325833&req=5

Figure 7: nup2- and nupA- mutants display defects in mitotic exit. (A) Images captured during live-cell imaging of wild-type (SM116) and (B) nupA- (ΔnupA, from heterokaryon SM127) strains during mitosis, monitoring the INM marker GFP-AN0162 and NLS-DsRed. Without NupA function, the nucleus fails to complete karyokinesis and forms one polyploid nucleus after mitosis. GFP-AN0162 does not locate to the periphery of the nucleolus after anaphase as obviously as the wild type (compare structures at arrows). Pseudocoloring represents false coloring using the thermal color scale of ImageJ. The Fire Color lookup table was applied to grayscale images to produce false-color images (pixels with a value of 0 are white, and pixels with a value of 255 are black). Bar, ∼2.5 μm. (C) Mitosis of a wild type (strain HA375) following spindle and chromatin dynamics of four mitotic nuclei. Bar, ∼5 μm. (D) A mitotic depolyploidization event in a nupA- mutant (from heterokaryon SM98) showing multiple bipolar spindles forming in a polyploid nucleus that remains in an extended metaphase-like state before exiting mitosis. Bar, ∼5 μm. (E) Quantitation of the percentage of larger polyploid nuclei generated in wild-type (strain HA375) compared with nup2- and nupA- cells (heterokaryons SM96 and SM98, respectively).
Mentions: In cells lacking Nup2 or NupA, although the SAC is engaged causing mitotic delay, the cells do not all subsequently complete mitosis normally, even though the SAC is apparently fulfilled to allow progression into anaphase. This was revealed by monitoring formation of daughter nuclei in ΔnupA cells using the inner nuclear membrane (INM) marker AN0162-GFP in combination with NLS-DsRed. AN0162 is an INM marker that contains a C-terminal transmembrane domain and is similar to the Schizosaccharomyces pombe INM protein Bqt4 (unpublished data and annotated at AspGD as AN0162). During karyokinesis, the NE undergoes double restrictions and abscissions to generate daughter nuclei. This process also separates the nucleolus from nuclei (Ukil et al., 2009). Twenty percent of nupA- nuclei displayed defects during mitotic exit, and although two apparently normal G1 nuclei were initially formed, they remain associated via the NE, and karyokinesis failed, resulting in the formation of a single diploid nucleus (Figure 7, B and E). During failed nucleokinesis, AN0162 did not locate correctly around the nucleolus (compare Figure 7, A and B, arrow). Furthermore, after several rounds of mitosis, some mutant polyploid nuclei were seen to form multiple bipolar spindles during mitosis (Figure 7D), indicating that these nuclei were the products of more than one round of defective karyokinesis. Lack of Nup2 or NupA therefore compromises aspects of mitosis that are monitored by the SAC and also perturbs NE dynamics during mitotic exit, which can lead to failed karyokinesis.

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