Dataset Information

Efficient checkpoint signaling depends on the integrated activities of Bub1 and the RZZ complex

ABSTRACT: Kinetochore localized Mad1 is essential for generating a “wait anaphase” signal during mitosis hereby ensuring accurate chromosome segregation. Inconsistent models for the function and quantitative contribution of the two mammalian Mad1 kinetochore receptors: Bub1 and the Rod-Zwilch-ZW10 (RZZ) complex exist. By combining genome editing and RNAi we achieve penetrant removal of Bub1 and Rod in human cells, which reveals that efficient checkpoint signaling depends on the integrated activities of these proteins. Rod removal reduces the proximity of Bub1 and Mad1 and we can bypass the requirement for Rod by tethering Mad1 to kinetochores or increasing the strength of the Bub1-Mad1 interaction. We find that Bub1 has checkpoint functions independent of Mad1 localization that are supported by low levels of Bub1 suggesting a catalytic function. In conclusion, our results support an integrated model for the Mad1 receptors in which the primary role of RZZ is to localize Mad1 at kinetochores to generate the Mad1-Bub1 complex.

INSTRUMENT(S): Q Exactive

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Epithelial Cell, Hela Cell

DISEASE(S): Cervix Carcinoma

SUBMITTER: Fabian Coscia

LAB HEAD: Jakob Nilsson

PROVIDER: PXD012235 | Pride | 2019-02-19

REPOSITORIES: Pride

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Dataset's files

Source:

			Action	DRS
	20180803_QE9_nLC02_FaCo_SA_BUB3-IPs_KO04-Venus-BUB3_1.raw	Raw
	20180803_QE9_nLC02_FaCo_SA_BUB3-IPs_KO20-Venus-BUB3_1.raw	Raw
	20180803_QE9_nLC02_FaCo_SA_BUB3-IPs_WT-Hela_Venus-BUB3_1.raw	Raw
	20180803_QE9_nLC02_FaCo_SA_BUB3-IPs_WT-Hela_Venus_1.raw	Raw
	20181023_QE10_nLC14_FaCo_SA_JakobN_BUB3-IPs_KO04_2.raw	Raw

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Publications

Efficient mitotic checkpoint signaling depends on integrated activities of Bub1 and the RZZ complex.

Zhang Gang G Kruse Thomas T Guasch Boldú Claudia C Garvanska Dimitriya H DH Coscia Fabian F Mann Matthias M Barisic Marin M Nilsson Jakob J

The EMBO journal 20190219 7

Kinetochore localized Mad1 is essential for generating a "wait anaphase" signal during mitosis, hereby ensuring accurate chromosome segregation. Inconsistent models for the function and quantitative contribution of the two mammalian Mad1 kinetochore receptors: Bub1 and the Rod-Zw10-Zwilch (RZZ) complex exist. By combining genome editing and RNAi, we achieve penetrant removal of Bub1 and Rod in human cells, which reveals that efficient checkpoint signaling depends on the integrated activities of ...[more]

PMID: 30782962

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Project description:Cryptococcus neoformans is an opportunistic, human fungal pathogen which undergoes fascinating switches in cell cycle control and ploidy when it encounters stressful environments such as the human lung. Here we carry out a mechanistic analysis of the spindle checkpoint which regulates the metaphase to anaphase transition, focusing on Mps1 kinase and the downstream checkpoint components Mad1 and Mad2. We demonstrate that Cryptococcus mad1D or mad2D strains are unable to respond to microtubule perturbations, continuing to re-bud and divide, and die as a consequence. Fluorescent tagging of Chromosome 3, using a lacO array and mNeonGreen-lacI fusion protein, demonstrates that mad mutants are unable to maintain sister-chromatid cohesion in the absence of microtubule polymers. Thus, the classic checkpoint functions of the SAC are conserved in Cryptococcus. In interphase, GFP-Mad1 is enriched at the nuclear periphery, and it is recruited to unattached kinetochores in mitosis. Purification of GFP-Mad1 followed by mass spectrometric analysis of associated proteins show that it forms a complex with Mad2 and that it interacts with other checkpoint signalling components (Bub1) and effectors (Cdc20 and APC/C sub-units) in mitosis. We also demonstrate that overexpression of Mps1 kinase is sufficient to arrest Cryptococcus cells in mitosis, and show that this arrest is dependent on both Mad1 and Mad2. We find that a C-terminal fragment of Mad1 is an effective in vitro substrate for Mps1 kinase and map several Mad1 phosphorylation sites. Some sites are highly conserved within the C-terminal Mad1 structure and we demonstrate that mutation of threonine 667 (T667A) leads to loss of checkpoint signalling and abrogation of the GAL-MPS1 arrest. Thus Mps1-dependent phosphorylation of C-terminal Mad1 residues is a critical step in Cryptococcus spindle checkpoint signalling. We conclude that CnMps1 protein kinase, Mad1 and Mad2 proteins have all conserved their important, spindle checkpoint signalling roles helping ensure high fidelity chromosome segregation.