Mitotic Cyclin Ubiquitination
Mitotic Cyclin Ubiquitination - Related Videos
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Detection of Protein Ubiquitination
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Cited by 96 •
2009
Ubiquitination is a key posttranslational modification carried out by a set of three enzymes. Mutations of genes involved in this modification are associated with many different human diseases. Here, we describe protocols to detect protein ubiquitination in cultured cells in vivo and test tubes in vitro.
10:54
Studying Proteolysis of Cyclin B at the Single Cell Level in Whole Cell Populations
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Cited by 2 •
2012
Metaphase to anaphase transition is triggered through anaphase-promoting complex (APC/C)-dependent ubiquitination and subsequent destruction of cyclin B. Here, we established a system which, following pulse-chase labeling, allows monitoring cyclin B proteolysis in entire cell populations and facilitates the detection of interference by the mitotic checkpoint.
10:43
siRNA Screening to Identify Ubiquitin and Ubiquitin-like System Regulators of Biological Pathways in Cultured Mammalian Cells
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Cited by 4 •
2014
Here, we describe a methodology to perform a targeted siRNA “ubiquitome” screen to identify novel ubiquitin and ubiquitin-like regulators of the HIF1A-mediated cellular response to hypoxia. This can be adapted to any biological pathway where a robust read out of reporter activity is available.
02:27
The Mitotic Spindle
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2021
The mitotic spindle—or spindle apparatus—is a eukaryotic, cytoskeletal structure made up of long protein fibers called microtubules. Formed during cell division, the spindle separates sister chromatids and moves them to opposite ends of a parental cell, where the now individual chromosomes are distributed to two daughter cell nuclei. The bipolar configuration of the mitotic spindle facilitates chromosomal segregation, preparing the cell for division. One mechanism that ensures bipolar mitotic...
10:10
Observing Mitotic Division and Dynamics in a Live Zebrafish Embryo
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Cited by 8 •
2016
Mitosis is critical to every living organism and defects often lead to cancer and developmental disorders. Using this imaging protocol and zebrafish as a model system, researchers can visualize mitosis in a live vertebrate organism and the multitude of defects that arise when mitotic processes are defective.
FAQs
The spindle checkpoint acts as a timing gate for APC/C activity toward cyclin B. Before the checkpoint is satisfied, cyclin B remains protected from this destruction pathway, preserving cyclin-dependent kinase 1 activity during the earlier part of mitosis. Once the checkpoint is satisfied, APC/C-mediated ubiquitination can proceed, linking chromosome-segregation readiness to the onset of mitotic exit.
Ubiquitin chains provide the destruction signal placed on cyclin B by APC/C. The 26S proteasome recognizes this tagged form and degrades the cyclin, rather than merely modifying its activity temporarily. This arrangement converts a regulatory decision made by the ubiquitin ligase into a targeted reduction of a specific mitotic regulator.
Cyclin B destruction reduces cyclin-dependent kinase 1 activity, creating a biochemical switch that supports the transition out of mitosis. This decline helps coordinate sister chromatid separation with later mitotic events instead of allowing high mitotic kinase activity to persist. Consequently, regulated kinase downregulation connects proteolysis with orderly chromosome segregation and mitotic exit.
Its timing is essential because cyclin destruction is coupled to spindle checkpoint satisfaction and anaphase. Premature activation would uncouple cyclin-dependent kinase 1 reduction from the cell’s readiness to segregate chromosomes, while delayed destruction could postpone mitotic exit. The process therefore functions as a coordinated cell-cycle switch, not simply as continuous protein turnover.
Studies can connect APC/C activity, cyclin B destruction, cyclin-dependent kinase 1 reduction, sister chromatid separation, and mitotic exit as linked outcomes. Examining these events together helps determine whether the transition is coordinated correctly. It also provides a way to relate molecular ubiquitination control to chromosome-segregation accuracy at the cellular level.
The pathway offers several connected points for analysis: the checkpoint-dependent activation of APC/C, ubiquitin tagging of cyclin B, recognition by the 26S proteasome, and the resulting change in cyclin-dependent kinase 1 activity. Considering these stages together allows researchers to study how a regulated protein-destruction event produces a defined cell-cycle transition.
Because mitotic cyclin ubiquitination helps coordinate chromosome segregation and mitotic exit, defects in the pathway can be examined as potential sources of abnormal cell-cycle control. Its study connects molecular regulation by APC/C and the proteasome with broader questions about proliferation. This makes the process useful for investigating how failures in mitotic regulation may affect cellular behavior.