scholarly journals Hepatitis C Virus Core Functions as a Suppressor of Cyclin-dependent Kinase-activating Kinase and Impairs Cell Cycle Progression

2004 ◽  
Vol 279 (12) ◽  
pp. 11719-11726 ◽  
Author(s):  
Kazuyoshi Ohkawa ◽  
Hisashi Ishida ◽  
Fumihiko Nakanishi ◽  
Atsushi Hosui ◽  
Keiji Ueda ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Cell Cycle Progression ◽  
Cyclin Dependent Kinase ◽  
Cycle Progression ◽  
Virus Core

scholarly journals Budding yeast relies on G1 cyclin specificity to couple cell cycle progression with morphogenetic development

2021 ◽  
Vol 7 (23) ◽  
pp. eabg0007
Author(s):  
Deniz Pirincci Ercan ◽  
Florine Chrétien ◽  
Probir Chakravarty ◽  
Helen R. Flynn ◽  
Ambrosius P. Snijders ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Budding Yeast ◽  
Quantitative Model ◽  
Cyclin Dependent Kinase ◽  
Cycle Progression ◽  
Model Cell ◽  
Mitotic Cyclin ◽  
Substrate Phosphorylation ◽  
The Cost

Two models have been put forward for cyclin-dependent kinase (Cdk) control of the cell cycle. In the qualitative model, cell cycle events are ordered by distinct substrate specificities of successive cyclin waves. Alternatively, in the quantitative model, the gradual rise of Cdk activity from G1 phase to mitosis leads to ordered substrate phosphorylation at sequential thresholds. Here, we study the relative contributions of qualitative and quantitative Cdk control in Saccharomyces cerevisiae. All S phase and mitotic cyclins can be replaced by a single mitotic cyclin, albeit at the cost of reduced fitness. A single cyclin can also replace all G1 cyclins to support ordered cell cycle progression, fulfilling key predictions of the quantitative model. However, single-cyclin cells fail to polarize or grow buds and thus cannot survive. Our results suggest that budding yeast has become dependent on G1 cyclin specificity to couple cell cycle progression to essential morphogenetic events.

Cyclin specificity: how many wheels do you need on a unicycle?

2001 ◽  
Vol 114 (10) ◽  
pp. 1811-1820 ◽  
Author(s):  
M.E. Miller ◽  
F.R. Cross
Keyword(s):  
Cell Cycle ◽  
Subcellular Localization ◽  
Cell Cycle Progression ◽  
Eukaryotic Cell ◽  
Cyclin Dependent Kinase ◽  
Temporal Expression ◽  
Cycle Progression

Cyclin-dependent kinase (CDK) activity is essential for eukaryotic cell cycle events. Multiple cyclins activate CDKs in all eukaryotes, but it is unclear whether multiple cyclins are really required for cell cycle progression. It has been argued that cyclins may predominantly act as simple enzymatic activators of CDKs; in opposition to this idea, it has been argued that cyclins might target the activated CDK to particular substrates or inhibitors. Such targeting might occur through a combination of factors, including temporal expression, protein associations, and subcellular localization.

scholarly journals Molecular Evolution Allows Bypass of the Requirement for Activation Loop Phosphorylation of the Cdc28 Cyclin-Dependent Kinase

1998 ◽  
Vol 18 (5) ◽  
pp. 2923-2931 ◽  
Author(s):  
Frederick R. Cross ◽  
Kristi Levine
Keyword(s):  
Cell Cycle ◽  
Biological Activity ◽  
Cell Cycle Progression ◽  
Dna Amplification ◽  
Protein Kinase Activity ◽  
Activation Loop ◽  
Cyclin Dependent Kinase ◽  
High Biological Activity ◽  
Cycle Progression ◽  
Growth Defects

ABSTRACT Many protein kinases are regulated by phosphorylation in the activation loop, which is required for enzymatic activity. Glutamic acid can substitute for phosphothreonine in some proteins activated by phosphorylation, but this substitution (T169E) at the site of activation loop phosphorylation in the Saccharomyces cerevisiae cyclin-dependent kinase (Cdk) Cdc28p blocks biological function and protein kinase activity. Using cycles of error-prone DNA amplification followed by selection for successively higher levels of function, we identified mutant versions of Cdc28p-T169E with high biological activity. The enzymatic and biological activity of the mutant Cdc28p was essentially normally regulated by cyclin, and the mutants supported normal cell cycle progression and regulation. Therefore, it is not a requirement for control of the yeast cell cycle that Cdc28p be cyclically phosphorylated and dephosphorylated. TheseCDC28 mutants allow viability in the absence of Cak1p, the essential kinase that phosphorylates Cdc28p-T169, demonstrating that T169 phosphorylation is the only essential function of Cak1p. Some growth defects remain in suppressed cak1 cdc28 strains carrying the mutant CDC28 genes, consistent with additional nonessential roles for CAK1.

scholarly journals Structure-function relationships of the yeast cyclin-dependent kinase Pho85.

1995 ◽  
Vol 15 (10) ◽  
pp. 5482-5491 ◽  
Author(s):  
R C Santos ◽  
N C Waters ◽  
C L Creasy ◽  
L W Bergman
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Structure Function ◽  
Cell Cycle Progression ◽  
Substrate Recognition ◽  
The Other ◽  
Cyclin Dependent Kinase ◽  
Cycle Progression ◽  
Cyclin Dependent Kinases ◽  
Induced Mutagenesis

The PHO85 gene of Saccharomyces cerevisiae encodes a cyclin-dependent kinase involved in both transcriptional regulation and cell cycle progression. Although a great deal is known concerning the structure, function, and regulation of the highly homologous Cdc28 protein kinase, little is known concerning these relationships in regard to Pho85. In this study, we constructed a series of Pho85-Cdc28 chimeras to map the region(s) of the Pho85 molecule that is critical for function of Pho85 in repression of acid phosphatase (PHO5) expression. Using a combination of site-directed and ethyl methanesulfonate-induced mutagenesis, we have identified numerous residues critical for either activation of the Pho85 kinase, interaction of Pho85 with the cyclin-like molecule Pho80, or substrate recognition. Finally, analysis of mutations analogous to those previously identified in either Cdc28 or cdc2 of Schizosaccharomyces pombe suggested that the inhibition of Pho85-Pho80 activity in mechanistically different from that seen in the other cyclin-dependent kinases.

Interleukin-7 promotes survival and cell cycle progression of T-cell acute lymphoblastic leukemia cells by down-regulating the cyclin-dependent kinase inhibitor p27kip1

Blood ◽  
2001 ◽  
Vol 98 (5) ◽  
pp. 1524-1531 ◽  
Author(s):  
Joao T. Barata ◽  
Angelo A. Cardoso ◽  
Lee M. Nadler ◽  
Vassiliki A. Boussiotis
Keyword(s):  
Cell Cycle ◽  
T Cell ◽  
Cell Cycle Progression ◽  
Lymphoblastic Leukemia ◽  
Cyclin Dependent Kinase ◽  
Malignant Cells ◽  
Cycle Progression ◽  
Interleukin 7 ◽  
Cell Acute Lymphoblastic Leukemia ◽  
Immature Thymocytes

In normal T-cell development interleukin-7 (IL-7) functions as an antiapoptotic factor by regulating bcl-2 expression in immature thymocytes and mature T cells. Similar to what occurs in normal immature thymocytes, prevention of spontaneous apoptosis by IL-7 in precursor T-cell acute lymphoblastic leukemia (T-ALL) cells correlates with up-regulation of bcl-2. IL-7 is also implicated in leukemogenesis because IL-7 transgenic mice develop lymphoid malignancies, suggesting that IL-7 may regulate the generation and expansion of malignant cells. This study shows that in the presence of IL-7, T-ALL cells not only up-regulated bcl-2 expression and escaped apoptosis but also progressed in the cell cycle, resulting in sequential induction of cyclin D2 and cyclin A. Down-regulation of p27kip1 was mandatory for IL-7–mediated cell cycle progression and temporally coincided with activation of cyclin-dependent kinase (cdk)4 and cdk2 and hyperphosphorylation of Rb. Strikingly, forced expression of p27kip1 in T-ALL cells not only prevented cell cycle progression but also reversed IL-7–mediated up-regulation of bcl-2 and promotion of viability. These results show for the first time that a causative link between IL-7–mediated proliferation and p27kip1 down-regulation exists in malignant T cells. Moreover, these results suggest that p27kip1 may function as a tumor suppressor gene not only because it is a negative regulator of cell cycle progression but also because it is associated with induction of apoptosis of primary malignant cells.

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