Distinct roles for cyclin-dependent kinases in cell cycle control

Science ◽  
1993 ◽  
Vol 262 (5142) ◽  
pp. 2050-2054 ◽  
Author(s):  
S van den Heuvel ◽  
E Harlow
1994 ◽  
Vol 127 (2) ◽  
pp. 467-478 ◽  
Author(s):  
J P Tassan ◽  
S J Schultz ◽  
J Bartek ◽  
E A Nigg

The activity of cyclin-dependent kinases (cdks) depends on the phosphorylation of a residue corresponding to threonine 161 in human p34cdc2. One enzyme responsible for phosphorylating this critical residue has recently been purified from Xenopus and starfish. It was termed CAK (for cdk-activating kinase), and it was shown to contain p40MO15 as its catalytic subunit. In view of the cardinal role of cdks in cell cycle control, it is important to learn if and how CAK activity is regulated during the somatic cell cycle. Here, we report a molecular characterization of a human p40MO15 homologue and its associated CAK activity. We have cloned and sequenced a cDNA coding for human p40MO15, and raised specific polyclonal and monoclonal antibodies against the corresponding protein expressed in Escherichia coli. These tools were then used to demonstrate that p40MO15 protein expression and CAK activity are constant throughout the somatic cell cycle. Gel filtration suggests that active CAK is a multiprotein complex, and immunoprecipitation experiments identify two polypeptides of 34 and 32 kD as likely complex partners of p40MO15. The association of the three proteins is near stoichiometric and invariant throughout the cell cycle. Immunocytochemistry and biochemical enucleation experiments both demonstrate that p40MO15 is nuclear at all stages of the cell cycle (except for mitosis, when the protein redistributes throughout the cell), although the p34cdc2/cyclin B complex, one of the major purported substrates of CAK, occurs in the cytoplasm until shortly before mitosis. The absence of obvious changes in CAK activity in exponentially growing cells constitutes a surprise. It suggests that the phosphorylation state of threonine 161 in p34cdc2 (and the corresponding residue in other cdks) may be regulated primarily by the availability of the cdk/cyclin substrates, and by phosphatase(s).


2020 ◽  
Vol 31 (26) ◽  
pp. 2871-2873
Author(s):  
Paul Nurse

Cell cycle mutants in the budding and fission yeasts have played critical roles in working out how the eukaryotic cell cycle operates and is controlled. The starting point was Lee Hartwell’s 1970s landmark papers describing the first cell division cycle (CDC) mutants in budding yeast. These mutants were blocked at different cell cycle stages and so were unable to complete the cell cycle, thus defining genes necessary for successful cell division. Inspired by Hartwell’s work, I isolated CDC mutants in the very distantly related fission yeast. This started a program of searches for mutants in fission yeast that revealed a range of phenotypes informative about eukaryotic cell cycle control. These included mutants defining genes that were rate-limiting for the onset of mitosis and of the S-phase, that were responsible for there being only one S-phase in each cell cycle, and that ensured that mitosis only took place when S-phase was properly completed. This is a brief account of the discovery of these mutants and how they led to the identification of cyclin-dependent kinases as core to these cell cycle controls.


2021 ◽  
Author(s):  
Souradeep Basu ◽  
Paul Nurse ◽  
Andrew Jones

Abstract Cyclin dependent kinases (CDKs) lie at the heart of eukaryotic cell cycle control, with different Cyclin-CDK complexes initiating DNA replication (S-CDKs) and mitosis (M-CDKs). However, the principles on which Cyclin-CDKs organise the temporal order of cell cycle events are contentious. The currently most widely accepted model, is that the S-CDKs and M-CDKs are functionally specialised, with significant different substrate specificities to execute different cell cycle events. A second model is that S-CDKs and M-CDKs are redundant with each other, with both acting as sources of overall cellular CDK activity. Here we reconcile these two views of core cell cycle control. Using a multiplexed phosphoproteomics assay of in vivo S-CDK and M-CDK activities in fission yeast, we show that S-CDK and M-CDK substrate specificities are very similar, showing that S-CDKs are not completely specialised for S-phase alone. Normally S-CDK cannot undergo mitosis, but is able to do so when Protein Phosphatase 1 (PP1) is removed from the centrosome, allowing several mitotic substrates to be better phosphorylated by S-CDK in vivo. Thus, an increase in S-CDK activity in vivo is sufficient to allow S-CDK to carry out M-CDK function. Therefore, we unite the two opposing views of cell cycle control, showing that the core cell cycle engine which temporally orders cell cycle progression is largely based upon a quantitative increase of CDK activity through the cell cycle, combined with minor qualitative differences in catalytic specialisation of S-CDKs and M-CDKs.


Cells ◽  
2022 ◽  
Vol 11 (2) ◽  
pp. 279
Author(s):  
Zhi-Liang Zheng

Cell cycle control is vital for cell proliferation in all eukaryotic organisms. The entire cell cycle can be conceptually separated into four distinct phases, Gap 1 (G1), DNA synthesis (S), G2, and mitosis (M), which progress sequentially. The precise control of transcription, in particular, at the G1 to S and G2 to M transitions, is crucial for the synthesis of many phase-specific proteins, to ensure orderly progression throughout the cell cycle. This mini-review highlights highly conserved transcriptional regulators that are shared in budding yeast (Saccharomyces cerevisiae), Arabidopsis thaliana model plant, and humans, which have been separated for more than a billion years of evolution. These include structurally and/or functionally conserved regulators cyclin-dependent kinases (CDKs), RNA polymerase II C-terminal domain (CTD) phosphatases, and the classical versus shortcut models of Pol II transcriptional control. A few of CDKs and CTD phosphatases counteract to control the Pol II CTD Ser phosphorylation codes and are considered critical regulators of Pol II transcriptional process from initiation to elongation and termination. The functions of plant-unique CDKs and CTD phosphatases in relation to cell division are also briefly summarized. Future studies towards testing a cooperative transcriptional mechanism, which is proposed here and involves sequence-specific transcription factors and the shortcut model of Pol II CTD code modulation, across the three eukaryotic kingdoms will reveal how individual organisms achieve the most productive, large-scale transcription of phase-specific genes required for orderly progression throughout the entire cell cycle.


2020 ◽  
Vol 5 (1) ◽  
pp. 1-9
Author(s):  
Muzna Shah ◽  
Muhammad Fazal Hussain Qureshi ◽  
Danish Mohammad ◽  
Mahira Lakhani ◽  
Tabinda Urooj ◽  
...  

Cyclin-dependent kinases (CDKs) are the catalytic subunits or protein kinases characterized by separate subunit “cyclin” that are essential for their enzymatic activity. CDKs play important roles in the control of cell cycle progression, cell division, neuronal function, epigenetic regulation, metabolism, stem cell renewal and transcription. However, they can accomplish some of these tasks independently, without binding with cyclin protein or kinase activity. Thus, so far, twenty different CDKs and cyclins have been reported in mammalian cells. The evolutionary expansion of the CDK family in mammals led to the division of CDKs into three cell-cycle-related subfamilies (Cdk1, Cdk4 and Cdk5) and five transcriptional subfamilies (Cdk7, Cdk8, Cdk9, Cdk11 and Cdk20). In this review, we summarizes that how CDKs are traditionally involve their latest revelations, their functional diversity beyond cell cycle regulation and their impact on development of disease in mammals.  


2018 ◽  
Vol 218 (1) ◽  
pp. 171-189 ◽  
Author(s):  
Kyle D. Moran ◽  
Hui Kang ◽  
Ana V. Araujo ◽  
Trevin R. Zyla ◽  
Koji Saito ◽  
...  

In many cells, morphogenetic events are coordinated with the cell cycle by cyclin-dependent kinases (CDKs). For example, many mammalian cells display extended morphologies during interphase but round up into more spherical shapes during mitosis (high CDK activity) and constrict a furrow during cytokinesis (low CDK activity). In the budding yeast Saccharomyces cerevisiae, bud formation reproducibly initiates near the G1/S transition and requires activation of CDKs at a point called “start” in G1. Previous work suggested that CDKs acted by controlling the ability of cells to polarize Cdc42, a conserved Rho-family GTPase that regulates cell polarity and the actin cytoskeleton in many systems. However, we report that yeast daughter cells can polarize Cdc42 before CDK activation at start. This polarization operates via a positive feedback loop mediated by the Cdc42 effector Ste20. We further identify a major and novel locus of CDK action downstream of Cdc42 polarization, affecting the ability of several other Cdc42 effectors to localize to the polarity site.


Parasitology ◽  
2016 ◽  
Vol 144 (5) ◽  
pp. 571-582 ◽  
Author(s):  
ERICK AMADOR ◽  
KARLA LÓPEZ-PACHECO ◽  
NATALY MORALES ◽  
ROBERTO CORIA ◽  
IMELDA LÓPEZ-VILLASEÑOR

SUMMARYCyclin-dependent kinases (CDKs) have important roles in regulating key checkpoints between stages of the cell cycle. Their activity is tightly regulated through a variety of mechanisms, including through binding with cyclin proteins and the Cdc2/Cdc28 kinase subunit (CKS), and their phosphorylation at specific amino acids. Studies of the components involved in cell cycle control in parasitic protozoa are limited. Trichomonas vaginalis is the causative agent of trichomoniasis in humans and is therefore important in public health; however, some of the basic biological processes used by this organism have not been defined. Here, we characterized proteins potentially involved in cell cycle regulation in T. vaginalis. Three genes encoding protein kinases were identified in the T. vaginalis genome, and the corresponding recombinant proteins (TvCRK1, TvCRK2, TvCRK5) were studied. These proteins displayed similar sequence features to CDKs. Two genes encoding CKSs were also identified, and the corresponding recombinant proteins were found to interact with TvCRK1 and TvCRK2 by a yeast two-hybrid system. One putative cyclin B protein from T. vaginalis was found to bind to and activate the kinase activities of TvCRK1 and TvCRK5, but not TvCRK2. This work is the first characterization of proteins involved in cell cycle control in T. vaginalis.


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