scholarly journals Reversal of Growth Suppression by p107 via Direct Phosphorylation by Cyclin D1/Cyclin-Dependent Kinase 4

2002 ◽  
Vol 22 (7) ◽  
pp. 2242-2254 ◽  
Author(s):  
Xiaohong Leng ◽  
Martin Noble ◽  
Peter D. Adams ◽  
Jun Qin ◽  
J. Wade Harper
Keyword(s):  
Cell Cycle ◽  
Cyclin D1 ◽  
Control Cell ◽  
Growth Suppression ◽  
Cyclin Dependent Kinase ◽  
Culture Cells ◽  
Cycle Arrest ◽  
A Cell ◽  
Control Cell Division

ABSTRACT p107 functions to control cell division and development through interaction with members of the E2F family of transcription factors. p107 is phosphorylated in a cell cycle-regulated manner, and its phosphorylation leads to its release from E2F. Although it is known that p107 physically associates with E- and A-type cyclin/cyclin-dependent kinase 2 (Cdk2) complexes through a cyclin-binding RXL motif located in the spacer domain, the mechanisms underlying p107 inactivation via phosphorylation remain poorly defined. Recent genetic evidence indicates a requirement for cyclin D1/Cdk4 complexes in p107 inactivation. In this work, we provide direct biochemical evidence for the involvement of cyclin D1/Cdk4 in the inactivation of p107's growth-suppressive function. While coexpression of cyclin D1/Cdk4 can reverse the cell cycle arrest properties of p107 in Saos-2 cells, we find that p107 in which the Lys-Arg-Arg-Leu sequence of the RXL motif is replaced by four alanine residues is largely refractory to inactivation by cyclin D/Cdk4, indicating a role for this motif in p107 inactivation without a requirement for its tight interaction with cyclin D1/Cdk4. We identified four phosphorylation sites in p107 (Thr-369, Ser-640, Ser-964, and Ser-975) that are efficiently phosphorylated by Cdk4 but not by Cdk2 in vitro and are also phosphorylated in tissue culture cells. Growth suppression by p107 containing nonphosphorylatable residues in these four sites is not reversed by coexpression of cyclin D1/Cdk4. In model p107 spacer region peptides, phosphorylation of S640 by cyclin D1/Cdk4 is strictly dependent upon an intact RXL motif, but phosphorylation of this site in the absence of an RXL motif can be partially restored by replacement of S643 by arginine. This suggests that one role for the RXL motif is to facilitate phosphorylation of nonconsensus Cdk substrates. Taken together, these data indicate that p107 is inactivated by cyclin D1/Cdk4 via direct phosphorylation and that the RXL motif of p107 plays a role in its inactivation by Cdk4 in the absence of stable binding.

scholarly journals Growth Suppression by Acute PromyelocyticLeukemia-Associated Protein PLZF Is Mediated by Repression ofc-mycExpression

2003 ◽  
Vol 23 (24) ◽  
pp. 9375-9388 ◽  
Author(s):  
Melanie J. McConnell ◽  
Nathalie Chevallier ◽  
Windy Berkofsky-Fessler ◽  
Jena M. Giltnane ◽  
Rupal B. Malani ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Growth ◽  
Cell Cycle Arrest ◽  
Target Genes ◽  
Ectopic Expression ◽  
Growth Suppression ◽  
Quiescent State ◽  
Cycle Arrest

ABSTRACT The transcriptional repressor PLZF was identified by its translocation with retinoic acid receptor alpha in t(11;17) acute promyelocytic leukemia (APL). Ectopic expression of PLZF leads to cell cycle arrest and growth suppression, while disruption of normal PLZF function is implicated in the development of APL. To clarify the function of PLZF in cell growth and survival, we used an inducible PLZF cell line in a microarray analysis to identify the target genes repressed by PLZF. One prominent gene identified was c-myc. The array analysis demonstrated that repression of c-myc by PLZF led to a reduction in c-myc-activated transcripts and an increase in c-myc-repressed transcripts. Regulation of c-myc by PLZF was shown to be both direct and reversible. An interaction between PLZF and the c-myc promoter could be detected both in vitro and in vivo. PLZF repressed the wild-type c-myc promoter in a reporter assay, dependent on the integrity of the binding site identified in vitro. PLZF binding in vivo was coincident with a decrease in RNA polymerase occupation of the c-myc promoter, indicating that repression occurred via a reduction in the initiation of transcription. Finally, expression of c-myc reversed the cell cycle arrest induced by PLZF. These data suggest that PLZF expression maintains a cell in a quiescent state by repressing c-myc expression and preventing cell cycle progression. Loss of this repression through the translocation that occurs in t(11;17) would have serious consequences for cell growth control.

scholarly journals Differential Roles for Cyclin-Dependent Kinase Inhibitors p21 and p16 in the Mechanisms of Senescence and Differentiation in Human Fibroblasts

1999 ◽  
Vol 19 (3) ◽  
pp. 2109-2117 ◽  
Author(s):  
Gretchen H. Stein ◽  
Linda F. Drullinger ◽  
Alexandre Soulard ◽  
Vjekoslav Dulić
Keyword(s):  
Cell Cycle ◽  
Cyclin D1 ◽  
Cell Cycle Arrest ◽  
Early Stage ◽  
Cyclin E ◽  
Human Fibroblasts ◽  
Senescent Cell ◽  
Nuclear Antigen ◽  
Cyclin Dependent Kinase ◽  
Cycle Arrest

ABSTRACT The irreversible G1 arrest in senescent human diploid fibroblasts is probably caused by inactivation of the G1cyclin–cyclin-dependent kinase (Cdk) complexes responsible for phosphorylation of the retinoblastoma protein (pRb). We show that the Cdk inhibitor p21Sdi1,Cip1,Waf1, which accumulates progressively in aging cells, binds to and inactivates all cyclin E-Cdk2 complexes in senescent cells, whereas in young cells only p21-free Cdk2 complexes are active. Furthermore, the senescent-cell-cycle arrest occurs prior to the accumulation of the Cdk4-Cdk6 inhibitor p16Ink4a, suggesting that p21 may be sufficient for this event. Accordingly, cyclin D1-associated phosphorylation of pRb at Ser-780 is lacking even in newly senescent fibroblasts that have a low amount of p16. Instead, the cyclin D1-Cdk4 and cyclin D1-Cdk6 complexes in these cells are associated with an increased amount of p21, suggesting that p21 may be responsible for inactivation of both cyclin E- and cyclin D1-associated kinase activity at the early stage of senescence. Moreover, even in the late stage of senescence when p16 is high, cyclin D1-Cdk4 complexes are persistent, albeit reduced by ≤50% compared to young cells. We also provide new evidence that p21 may play a role in inactivation of the DNA replication factor proliferating cell nuclear antigen during early senescence. Finally, because p16 accumulates in parallel with the increases in senescence-associated β-Gal activity and cell volume that characterize the senescent phenotype, we suggest that p16 upregulation may be part of a differentiation program that is turned on in senescent cells. Since p21 decreases after senescence is achieved, this upregulation of p16 may be essential for maintenance of the senescent-cell-cycle arrest.

scholarly journals Isoliquiritigenin inhibits the proliferation, migration and metastasis of Hep3B cells via suppressing cyclin D1 and PI3K/AKT pathway

2020 ◽  
Vol 40 (1) ◽  
Author(s):  
Yun Huang ◽  
Chen Liu ◽  
Wu-Cha Zeng ◽  
Guo-Yan Xu ◽  
Jian-Min Wu ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cyclin D1 ◽  
Inhibitory Effect ◽  
Cycle Arrest ◽  
Novel Drugs ◽  
Epithelial Marker ◽  
Hep3b Cells ◽  
Induced Apoptosis

Abstract The overall survival rate of patients with hepatocellular carcinoma (HCC) has remained unchanged over the last several decades. Therefore, novel drugs and therapies are required for HCC treatment. Isoliquiritigenin (ISL), a natural flavonoid predominantly isolated from the traditional Chinese medicine Glycyrrhizae Radix (Licorice), has a high anticancer potential and broad application value in various cancers. Here, we aimed to investigate the anticancer role of ISL in the HCC cell line Hep3B. Functional analysis revealed that ISL inhibited the proliferation of Hep3B cells by causing G1/S cell cycle arrest in vitro. Meanwhile, the inhibitory effect of ISL on proliferation was also observed in vivo. Further analysis revealed that ISL could suppress the migration and metastasis of Hep3B cells in vitro and in vivo. Mechanistic analysis revealed that ISL inhibited cyclin D1 and up-regulated the proteins P21, P27 that negatively regulate the cell cycle. Furthermore, ISL induced apoptosis while inhibiting cell cycle transition. In addition, phosphatidylinositol 3′-kinase/protein kinase B (PI3K/AKT) signal pathway was suppressed by ISL treatment, and the epithelial marker E-cadherin was up-regulated when the mesenchymal markers Vimentin and N-cadherin were down-regulated. In brief, our findings suggest that ISL could be a promising agent for preventing HCC tumorigenesis and metastasis.

scholarly journals Ketamine Activates Cell Cycle Signaling and Apoptosis in the Neonatal Rat Brain

2010 ◽  
Vol 112 (5) ◽  
pp. 1155-1163 ◽  
Author(s):  
Sulpicio G. Soriano ◽  
Qian Liu ◽  
Jing Li ◽  
Jia-Ren Liu ◽  
Xiao Hui Han ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Death ◽  
Cyclin D1 ◽  
Small Interfering Rna ◽  
Caspase 3 ◽  
Primary Neurons ◽  
Cyclin Dependent Kinase ◽  
Cell Cycle Signaling ◽  
Interfering Rna

Background Prolonged exposure to ketamine results in accelerated neurodegeneration and neurocognitive deficits in the neonatal rats. Experimental models of neurodegeneration have implicated reentry of postmitotic neurons into the cell cycle, leading to cell death. The authors hypothesize that the ketamine-induced neuroapoptosis is partially due to aberrant cycle cell reentry. To explore this hypothesis, the authors characterized the effect of ketamine on the cell cycle signaling pathway in the developing rodent brain in vivo and in vitro. Methods Postnatal day 7 rat pups and primary neurons were used for the experiments. Each rat pup received five intraperitoneal doses of either saline or ketamine (5, 10, and 20 mg/kg/dose) at 90-min intervals over 6 h. Primary neurons were exposed to varying concentrations of ketamine to determine the dose and duration effects. The expression of cell cycle proteins (cyclin D1, cyclin-dependent kinase 4, and E2F1), Bcl2-interacting mediator of cell death (Bim), and activated caspase-3 was determined. The effect of cyclin D1 knockdown by small interfering RNA was also examined in primary neurons incubated in ketamine. Results Ketamine mediated a dose- and time-dependent increase in expression of cell cycle proteins and activated caspase-3. Cyclin D1, cyclin-dependent kinase 4, E2F1, Bim, and cleaved caspase-3 expression increased at 12 h and peaked at 24 h in vitro. Knockdown of cyclin D1 by small interfering RNA attenuated Bim and cleaved caspase-3 expression. Conclusion These findings support a model in which ketamine induces aberrant cell cycle reentry, leading to apoptotic cell death in the developing rat brain.

scholarly journals In Vitro Validation of Network Pharmacology Predictions: Ginsenoside Rg3 Inhibits Hepatocellular Carcinoma Cell Proliferation via SIRT2

2021 ◽  
Vol 16 (4) ◽  
pp. 1934578X2110048
Author(s):  
Qiyu Zheng ◽  
Zhidong Qiu ◽  
Zhiyuan Sun ◽  
Lingling Cao ◽  
Fuqiang Li ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Cyclin D1 ◽  
Molecular Mechanisms ◽  
Interaction Network ◽  
Phase Cell ◽  
Network Pharmacology ◽  
Ginsenoside Rg3 ◽  
Cycle Arrest

To elucidate the molecular mechanisms underlying the therapeutic activity of ginsenoside Rg3 (Gs-Rg3) in the context of hepatocellular carcinoma (HCC). Methods Relevant databases were searched to identify protein targets that were both dysregulated and implicated in HCC, as well as targeted by Gs-Rg3. Generation of a protein-protein interaction network facilitated the selection of connected nodes for the construction of a shared disease- and drug-target interaction network model, and topological analysis identified the most highly connected nodes. Targets were annotated with their associated Gene Ontology terms, followed by Kyoto Encyclopedia of Genes and Genomes biological pathway enrichment analysis. In vitro experiments using 2 hours CC cell lines (Bel-7402 and HCCLM3) were performed to investigate the impact of Gs-Rg3 on cell proliferation, viability, cell cycle, cyclin D1 and sirtuin 2 (SIRT2) levels, and global cellular histone acetylation (specifically H3K18ac and H4K16ac). Results Network pharmacology suggested that Gs-Rg3 synergistically targets multiple proteins and pathways relevant to HCC pathogenesis, including those involved in cell cycle and proliferation. In vitro experiments confirmed that Gs-Rg3 dose-dependently inhibits cell proliferation and viability; induces G1 phase cell cycle arrest; decreases cyclin D1, cyclin-dependent kinase 2 (CDK2), and SIRT2 levels; and enhances global H3K18ac and H4K16ac. Conclusions Hypotheses derived from the network analysis were confirmed in vitro. Gs-Rg3 induces G1 phase cell cycle arrest, concomitant with decreased cyclin D1 and CDK2 levels, suggesting a possible mechanism for inhibiting proliferation. In addition, Gs-Rg3 decreases SIRT2 levels, concomitant with enhanced global H3K18ac and H4K16ac. These findings provide a theoretical basis and a support for further preclinical study of the safety and antineoplastic molecular mechanisms of Gs-Rg3, with the goal of eventual clinical translation.

scholarly journals Requirement of Cyclin E-Cdk2 Inhibition in p16INK4a-Mediated Growth Suppression

1998 ◽  
Vol 18 (9) ◽  
pp. 5284-5290 ◽  
Author(s):  
Hong Jiang ◽  
Hubert S. Chou ◽  
Liang Zhu
Keyword(s):  
Cell Cycle ◽  
Cyclin D1 ◽  
Tumor Cells ◽  
Kinase Activity ◽  
Cyclin E ◽  
Growth Suppression ◽  
Dominant Negative ◽  
Cyclin D ◽  
Loss Of Function

ABSTRACT Loss-of-function mutations of p16 INK4a have been identified in a large number of human tumors. An established biochemical function of p16 is its ability to specifically inhibit cyclin D-dependent kinases in vitro, and this inhibition is believed to be the cause of the p16-mediated G1 cell cycle arrest after reintroduction of p16 into p16-deficient tumor cells. However, a mutant of Cdk4, Cdk4N158, designed to specifically inhibit cyclin D-dependent kinases through dominant negative interference, was unable to arrest the cell cycle of the same cells (S. van den Heuvel and E. Harlow, Science 262:2050–2054, 1993). In this study, we determined functional differences between p16 and Cdk4N158. We show that p16 and Cdk4N158 inhibit the kinase activity of cellular cyclin D1 complexes through different mechanisms. p16 dissociated cyclin D1-Cdk4 complexes with the release of bound p27 KIP1 , while Cdk4N158 formed complexes with cyclin D1 and p27. In cells induced to overexpress p16, a higher portion of cellular p27 formed complexes with cyclin E-Cdk2, and Cdk2-associated kinase activities were correspondingly inhibited. Cells engineered to express moderately elevated levels of cyclin E became resistant to p16-mediated growth suppression. These results demonstrate that inhibition of cyclin D-dependent kinase activity may not be sufficient to cause G1 arrest in actively proliferating tumor cells. Inhibition of cyclin E-dependent kinases is required in p16-mediated growth suppression.

scholarly journals Schlafen-1 causes a cell cycle arrest by inhibiting induction of cyclin D1.

2016 ◽  
Vol 291 (48) ◽  
pp. 25278-25278 ◽  
Author(s):  
Gareth Brady ◽  
Louise Boggan ◽  
Andrew Bowie ◽  
Luke A. J. O'Neill
Keyword(s):  
Cell Cycle ◽  
Cyclin D1 ◽  
Cell Cycle Arrest ◽  
Cycle Arrest ◽  
A Cell

scholarly journals Schlafen-1 Causes a Cell Cycle Arrest by Inhibiting Induction of Cyclin D1

2005 ◽  
Vol 280 (35) ◽  
pp. 30723-30734 ◽  
Author(s):  
Gareth Brady ◽  
Louise Boggan ◽  
Andrew Bowie ◽  
Luke A. J. O'Neill
Keyword(s):  
Cell Cycle ◽  
Cyclin D1 ◽  
Cell Cycle Arrest ◽  
Cycle Arrest ◽  
A Cell

The Novel NFkB Inhibitor V1810 Induces Apoptosis and Cell Cycle Arrest in Multiple Myeloma Cells and Overcomes NFkB Mediated Drug Resistance.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 1715-1715 ◽  
Author(s):  
Felix Meinel ◽  
Sonja Mandl-Weber ◽  
Philipp Baumann ◽  
Johann Leban ◽  
Ralf Schmidmaier
Keyword(s):  
Cell Cycle ◽  
Multiple Myeloma ◽  
Drug Resistance ◽  
Cell Death ◽  
Cyclin D1 ◽  
Cell Cycle Arrest ◽  
Cyclin D3 ◽  
Cycle Arrest ◽  
Rpmi 8226

Abstract Multiple Myeloma (MM) is a fatal malignancy characterised by the accumulation and expansion of antibody producing plasma cells in the bone marrow. Evidence is increasing that nuclear factor kappa B (NFκB) is a promising target for new anti-myeloma therapies. In this study, we assessed the in vitro activity of V1810, a novel NFκB inhibitor. V1810 potently induces cell death in all tested MM cell lines (OPM-2, U266, NCI-H929, RPMI-8226) with an IC50 ranging between 5μM to 10μM as well as in primary MM cells from patients. Cell death induced by V1810 clearly shows biological features of apoptosis such as DNA fragmentation and caspase 3 cleavage. In OPM2, U266 and RPMI-8226 cells induction of apoptosis is accompanied by cell cycle arrest. Western blots revealed downregulation of cyclin D1 (U266) or cyclin D2 (OPM2, NCI-H929, RPMI-8226) respectively, but not cyclin D3. Consistent with the downregulation of cyclin D1/2, retinoblastoma protein was found to be hypophosphorylated. Considering that cyclin D1 and D2 are known to be NFκB target genes, this is in line with our finding that V1810 inhibits baseline NFκB activity in MM cells (36% relative reduction). Importantly, V1810 also abrogates NFκB activation induced by genotoxic drugs like melphalan and doxorubicin. Accordingly, V1810 and melphalan synergistically decrease MM cell viability. Taken together, V1810 induces apoptosis and cell cycle arrest in MM cells by inhibition of NFκB and overcomes NFκB mediated drug resistance to melphalan. The maximum tolerable dose (MTD) of V1810 in BalbC mice was 10mg/kg i.v. and plasma concentrations of 9.5μM are achievable in NRMI mice after 5mg/kg V1810 i.v., which corresponds well to the used in vitro concentrations. This study strongly supports the further development of NFkB inhibitors in MM, especially in combination with genotoxic drugs.

scholarly journals NSun2 Promotes Cell Growth via Elevating Cyclin-Dependent Kinase 1 Translation

2015 ◽  
Vol 35 (23) ◽  
pp. 4043-4052 ◽  
Author(s):  
Junyue Xing ◽  
Jie Yi ◽  
Xiaoyu Cai ◽  
Hao Tang ◽  
Zhenyun Liu ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Cell Division Cycle ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Cyclin Dependent Kinase ◽  
A Cell ◽  
Cycle Dependent ◽  
Insight Into

The tRNA methytransferase NSun2 promotes cell proliferation, but the molecular mechanism has not been elucidated. Here, we report that NSun2 regulates cyclin-dependent kinase 1 (CDK1) expression in a cell cycle-dependent manner. Knockdown of NSun2 decreased the CDK1 protein level, while overexpression of NSun2 elevated it without alteringCDK1mRNA levels. Further studies revealed that NSun2 methylatedCDK1mRNAin vitroand in cells and that methylation by NSun2 enhanced CDK1 translation. Importantly, NSun2-mediated regulation of CDK1 expression had an impact on the cell division cycle. These results provide new insight into the regulation of CDK1 during the cell division cycle.

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