CHO cells can be arrested with hydoxyurea at the beginning of the DNA synthesis phase of the cell cycle. Subsequent treatment with the xanthine, caffeine, induces cells to bypass the S-phase checkpoint and enter unscheduled mitosis [Schlegel and Pardee,1986, Science 232:1264-1266]. These treated cells build a normal spindle and distribute kinetochores, unattached to chromosomes, to their daughter cells [Brinkley et al.,1988, Nature 336:251-254; Zinkowski et al.,1991, J Cell Biol 113:1091-1110; Wise and Brinkley,1997, Cell Motil Cytoskeleton 36:291-302; Balczon et al.,2003, Chromosoma 112:96-102]. To investigate how these cells distribute kinetochores to daughter cells, we analyzed the spindle checkpoint components, Mad2, CENP-E, and the 3F3 phosphoepitope, using immunofluorescence and digital microscopy. Even though the kinetochores were unpaired and DNA was fragmented, the tension, alignment, and motor components of the checkpoint were found to be present and localized as predicted in prometaphase and metaphase. This unusual mitosis proves that a cell can successfully localize checkpoint proteins and divide even when kinetochores are unpaired and fragmented.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1002/cm.20310 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
The dependence of shugoshin on Bub1-kinase activity is dispensable for the maintenance of spindle assembly checkpoint response in Cryptococcus neoformans.
PLoS Genet
January 2025
Molecular Mycology Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru, India.
During chromosome segregation, the spindle assembly checkpoint (SAC) detects errors in kinetochore-microtubule attachments. Timely activation and maintenance of the SAC until defects are corrected is essential for genome stability. Here, we show that shugoshin (Sgo1), a conserved tension-sensing protein, ensures the maintenance of SAC signals in response to unattached kinetochores during mitosis in a basidiomycete budding yeast Cryptococcus neoformans.
View Article and Find Full Text PDFUnveiling the Movement of RanBP1 During the Cell Cycle and Its Interaction with a Cyclin-Dependent Kinase (CDK) in Plants.
Int J Mol Sci
December 2024
Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto 14040-901, SP, Brazil.
In the flower development study, we identified SCI1 (Stigma/style Cell-cycle Inhibitor 1), a regulator of cell proliferation. SCI1 interacts with NtCDKG;2 ( Cyclin-Dependent Kinase G;2), a homolog of human CDK11, which is responsible for RanGTP-dependent microtubule stabilization, regulating spindle assembly rate. In a Y2H screening of a cDNA library using NtCDKG;2 as bait, a RanBP1 (Ran-Binding Protein 1) was revealed as its interaction partner.
View Article and Find Full Text PDFMDM2 functions as a timer reporting the length of mitosis.
Nat Cell Biol
January 2025
Department of Biochemistry, University of Oxford, Oxford, UK.
Delays in mitosis trigger p53-dependent arrest in G1 of the next cell cycle, thus preventing repeated cycles of chromosome instability and aneuploidy. Here we show that MDM2, the p53 ubiquitin ligase, is a key component of the timer mechanism triggering G1 arrest in response to prolonged mitosis. This timer function arises due to the attenuation of protein synthesis in mitosis.
View Article and Find Full Text PDFExploring the Conformational Space of MPS1 Kinase Using Metadynamics.
Proteins
January 2025
Department of Chemistry and Chemical Biology, Indian Institute of Technology (Indian School of Mines), Dhanbad, India.
MPS1 kinase is a dual specificity kinase that plays an important role in the spindle assembly checkpoint mechanism during cell division. Overexpression of MPS1 kinase is reported in several cancers. However, drug discovery and development efforts targeting MPS1 kinase did not result in any clinically successful candidates.
View Article and Find Full Text PDFCul3 substrate adaptor SPOP targets Nup153 for degradation.
Mol Biol Cell
January 2025
Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA.
SPOP is a Cul3 substrate adaptor responsible for the degradation of many proteins related to cell growth and proliferation. Because mutation or misregulation of SPOP drives cancer progression, understanding the suite of SPOP substrates is important to understanding the regulation of cell proliferation. Here, we identify Nup153, a component of the nuclear basket of the nuclear pore complex, as a novel substrate of SPOP.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!