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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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NupA is essential and its deletion, similar to Nup2, does not affect initial short-term growth but causes mitotic DNA segregation defects. (A) a, Conidia from ∆nupA::pyrG transformant colonies were streaked on media supplemented with or without uridine and uracil (UU). Because nupA is essential, heterokaryons were generated after transformation that contained parental nuclei and nuclei carrying ∆nupA::pyrG. The heterokaryotic colonies produce uninucleated spores able to form colonies on +UU (parental spores can form colonies) but not on –UU (neither parental nor ∆nupA::pyrG spores can form colonies). b, Diagnostic PCR of heterokaryon SM51 showing two bands corresponding to the wild-type nupA and the ∆nupA::pyrG allele. (B) Bright-field images of germinated spores from the parental strain or heterokaryon SM51 producing wild-type and ∆nupA spores grown for 1 or 3 d at 22°C on the indicated media. Bar, ∼20 μm. (C) DAPI-stained wild-type germlings with typical one, two, four, and eight nuclei compared with ∆nupA germlings from heterokaryon SM51 of approximately the same length that had missegregated clustered DNA (arrows). Bar, ∼5 μm.
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Figure 3: NupA is essential and its deletion, similar to Nup2, does not affect initial short-term growth but causes mitotic DNA segregation defects. (A) a, Conidia from ∆nupA::pyrG transformant colonies were streaked on media supplemented with or without uridine and uracil (UU). Because nupA is essential, heterokaryons were generated after transformation that contained parental nuclei and nuclei carrying ∆nupA::pyrG. The heterokaryotic colonies produce uninucleated spores able to form colonies on +UU (parental spores can form colonies) but not on –UU (neither parental nor ∆nupA::pyrG spores can form colonies). b, Diagnostic PCR of heterokaryon SM51 showing two bands corresponding to the wild-type nupA and the ∆nupA::pyrG allele. (B) Bright-field images of germinated spores from the parental strain or heterokaryon SM51 producing wild-type and ∆nupA spores grown for 1 or 3 d at 22°C on the indicated media. Bar, ∼20 μm. (C) DAPI-stained wild-type germlings with typical one, two, four, and eight nuclei compared with ∆nupA germlings from heterokaryon SM51 of approximately the same length that had missegregated clustered DNA (arrows). Bar, ∼5 μm.

Mentions: Deletion of nupA led to the generation of diploid or heterokaryotic colonies, indicating that nupA, although poorly conserved, is essential. Using heterokaryon rescue (Osmani et al., 2006b), we identified heterokaryotic colonies that carried both ΔnupA and parental nuclei (Figure 3A). Diagnostic PCR confirmed the presence of the two genetically distinct types of nuclei (Figure 3Ab). ΔnupA mutant spores generated from the heterokaryotic colonies initially germinated and grew at a rate similar to wild-type spores but then stopped growing (Figure 3B) after several rounds of apparently defective mitosis, with nuclear DNA of the ΔnupA cells being missegregated and often clustered (Figure 3C). These phenotypes are very similar to the Δnup2 mutant (Osmani et al., 2006a), suggesting that Nup2 and NupA could have inter­dependent functions.


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 is essential and its deletion, similar to Nup2, does not affect initial short-term growth but causes mitotic DNA segregation defects. (A) a, Conidia from ∆nupA::pyrG transformant colonies were streaked on media supplemented with or without uridine and uracil (UU). Because nupA is essential, heterokaryons were generated after transformation that contained parental nuclei and nuclei carrying ∆nupA::pyrG. The heterokaryotic colonies produce uninucleated spores able to form colonies on +UU (parental spores can form colonies) but not on –UU (neither parental nor ∆nupA::pyrG spores can form colonies). b, Diagnostic PCR of heterokaryon SM51 showing two bands corresponding to the wild-type nupA and the ∆nupA::pyrG allele. (B) Bright-field images of germinated spores from the parental strain or heterokaryon SM51 producing wild-type and ∆nupA spores grown for 1 or 3 d at 22°C on the indicated media. Bar, ∼20 μm. (C) DAPI-stained wild-type germlings with typical one, two, four, and eight nuclei compared with ∆nupA germlings from heterokaryon SM51 of approximately the same length that had missegregated clustered DNA (arrows). Bar, ∼5 μm.
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Related In: Results  -  Collection

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Figure 3: NupA is essential and its deletion, similar to Nup2, does not affect initial short-term growth but causes mitotic DNA segregation defects. (A) a, Conidia from ∆nupA::pyrG transformant colonies were streaked on media supplemented with or without uridine and uracil (UU). Because nupA is essential, heterokaryons were generated after transformation that contained parental nuclei and nuclei carrying ∆nupA::pyrG. The heterokaryotic colonies produce uninucleated spores able to form colonies on +UU (parental spores can form colonies) but not on –UU (neither parental nor ∆nupA::pyrG spores can form colonies). b, Diagnostic PCR of heterokaryon SM51 showing two bands corresponding to the wild-type nupA and the ∆nupA::pyrG allele. (B) Bright-field images of germinated spores from the parental strain or heterokaryon SM51 producing wild-type and ∆nupA spores grown for 1 or 3 d at 22°C on the indicated media. Bar, ∼20 μm. (C) DAPI-stained wild-type germlings with typical one, two, four, and eight nuclei compared with ∆nupA germlings from heterokaryon SM51 of approximately the same length that had missegregated clustered DNA (arrows). Bar, ∼5 μm.
Mentions: Deletion of nupA led to the generation of diploid or heterokaryotic colonies, indicating that nupA, although poorly conserved, is essential. Using heterokaryon rescue (Osmani et al., 2006b), we identified heterokaryotic colonies that carried both ΔnupA and parental nuclei (Figure 3A). Diagnostic PCR confirmed the presence of the two genetically distinct types of nuclei (Figure 3Ab). ΔnupA mutant spores generated from the heterokaryotic colonies initially germinated and grew at a rate similar to wild-type spores but then stopped growing (Figure 3B) after several rounds of apparently defective mitosis, with nuclear DNA of the ΔnupA cells being missegregated and often clustered (Figure 3C). These phenotypes are very similar to the Δnup2 mutant (Osmani et al., 2006a), suggesting that Nup2 and NupA could have inter­dependent functions.

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