Witkin KL~Cohen-Fix O, 2012

Pubmed ID 22658600
Title The budding yeast nuclear envelope adjacent to the nucleolus serves as a membrane sink during mitotic delay.
Authors Keren L Witkin, Yolanda Chong, Sichen Shao, Micah T Webster, Sujoy Lahiri, Alison D Walters, Brandon Lee, Judice L Y Koh, William A Prinz, Brenda J Andrews, Orna Cohen-Fix
Abstract The mechanisms that dictate nuclear shape are largely unknown. Here we screened the budding yeast deletion collection for mutants with abnormal nuclear shape. A common phenotype was the appearance of a nuclear extension, particularly in mutants in DNA repair and chromosome segregation genes. Our data suggest that these mutations led to the abnormal nuclear morphology indirectly, by causing a checkpoint-induced cell-cycle delay. Indeed, delaying cells in mitosis by other means also led to the appearance of nuclear extensions, whereas inactivating the DNA damage checkpoint pathway in a DNA repair mutant reduced the fraction of cells with nuclear extensions. Formation of a nuclear extension was specific to a mitotic delay, because cells arrested in S or G2 had round nuclei. Moreover, the nuclear extension always coincided with the nucleolus, while the morphology of the DNA mass remained largely unchanged. Finally, we found that phospholipid synthesis continued unperturbed when cells delayed in mitosis, and inhibiting phospholipid synthesis abolished the formation of nuclear extensions. Our data suggest a mechanism that promotes nuclear envelope expansion during mitosis. When mitotic progression is delayed, cells sequester the added membrane to the nuclear envelope associated with the nucleolus, possibly to avoid disruption of intranuclear organization.
Citation Curr. Biol. 2012; 22:1128-33

Datasets

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Paper Phenotype Condition Reference Collection Tested mutants Data Details
Witkin KL~Cohen-Fix O, 2012 formation of nuclear extensions (Pus1-GFP) standard hap a ~4,300 Discrete

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