scholarly journals Regulation of Exit from Quiescence by p27 and Cyclin D1-CDK4

1998 ◽  
Vol 18 (11) ◽  
pp. 6605-6615 ◽  
Author(s):  
Mohamed H. Ladha ◽  
Kwang Y. Lee ◽  
Todd M. Upton ◽  
Michael F. Reed ◽  
Mark E. Ewen
Keyword(s):  
Cyclin D1 ◽  
Dominant Negative ◽  
Mitogen Activated Protein Kinase ◽  
Cyclin Dependent Kinase ◽  
3T3 Cells ◽  
Rate Limiting Step ◽  
Mitogen Activated Protein ◽  
Nih 3T3 ◽  
Rate Limiting ◽  
Nih 3T3 Cells

ABSTRACT The synthesis of cyclin D1 and its assembly with cyclin-dependent kinase 4 (CDK4) to form an active complex is a rate-limiting step in progression through the G1 phase of the cell cycle. Using an activated allele of mitogen-activated protein kinase kinase 1 (MEK1), we show that this kinase plays a significant role in positively regulating the expression of cyclin D1. This was found both in quiescent serum-starved cells and in cells expressing dominant-negative Ras. Despite the observation that cyclin D1 is a target of MEK1, in cycling cells, activated MEK1, but not cyclin D1, is capable of overcoming a G1 arrest induced by Ras inactivation. Either wild-type or catalytically inactive CDK4 cooperates with cyclin D1 in reversing the G1 arrest induced by inhibition of Ras activity. In quiescent NIH 3T3 cells expressing either ectopic cyclin D1 or activated MEK1, cyclin D1 is able to efficiently associate with CDK4; however, the complex is inactive. A significant percentage of the cyclin D1-CDK4 complexes are associated with p27 in serum-starved activated MEK1 or cyclin D1 cell lines. Reduction of p27 levels by expression of antisense p27 allows for S-phase entry from quiescence in NIH 3T3 cells expressing ectopic cyclin D1, but not in parental cells.

scholarly journals Leukemia-Related Transcription Factor TEL Is Negatively Regulated through Extracellular Signal-Regulated Kinase-Induced Phosphorylation

2004 ◽  
Vol 24 (8) ◽  
pp. 3227-3237 ◽  
Author(s):  
Kazuhiro Maki ◽  
Honoka Arai ◽  
Kazuo Waga ◽  
Ko Sasaki ◽  
Fumihiko Nakamura ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Dna Binding ◽  
Dominant Negative ◽  
Mitogen Activated Protein Kinase ◽  
Dominant Negative Effect ◽  
Phosphorylation Sites ◽  
3T3 Cells ◽  
Nih 3T3 ◽  
Nih 3T3 Cells

ABSTRACT TEL is an ETS family transcription factor that possesses multiple putative mitogen-activated protein kinase phosphorylation sites. We here describe the functional regulation of TEL via ERK pathways. Overexpressed TEL becomes phosphorylated in vivo by activated ERK. TEL is also directly phosphorylated in vitro by ERK. The inducible phosphorylation sites are Ser213 and Ser257. TEL binds to a common docking domain in ERK. In vivo ERK-dependent phosphorylation reduces trans-repressional and DNA-binding abilities of TEL for ETS-binding sites. A mutant carrying substituted glutamates on both Ser213 and Ser257 functionally mimics hyperphosphorylated TEL and also shows a dominant-negative effect on TEL-induced transcriptional suppression. Losing DNA-binding affinity through phosphorylation but heterodimerizing with unmodified TEL could be an underlying mechanism. Moreover, the glutamate mutant dominantly interferes with TEL-induced erythroid differentiation in MEL cells and growth suppression in NIH 3T3 cells. Finally, endogenous TEL is dephosphorylated in parallel with ERK inactivation in differentiating MEL cells and is phosphorylated through ERK activation in Ras-transformed NIH 3T3 cells. These data indicate that TEL is a constituent downstream of ERK in signal transduction systems and is physiologically regulated by ERK in molecular and biological features.

Activation of mitogen-activated protein kinase kinase by v-Raf in NIH 3T3 cells and in vitro

Science ◽  
1992 ◽  
Vol 257 (5075) ◽  
pp. 1404-1407 ◽  
Author(s):  
P Dent ◽  
W Haser ◽  
T. Haystead ◽  
L. Vincent ◽  
T. Roberts ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Mitogen Activated Protein Kinase ◽  
3T3 Cells ◽  
Mitogen Activated Protein ◽  
Nih 3T3 ◽  
Protein Kinase Kinase ◽  
Nih 3T3 Cells

scholarly journals Enhanced ROS Production in Oncogenically Transformed Cells Potentiates c-Jun N-Terminal Kinase and p38 Mitogen-Activated Protein Kinase Activation and Sensitization to Genotoxic Stress

2001 ◽  
Vol 21 (20) ◽  
pp. 6913-6926 ◽  
Author(s):  
Moran Benhar ◽  
Idan Dalyot ◽  
David Engelberg ◽  
Alexander Levitzki
Keyword(s):  
Protein Kinase ◽  
Mitogen Activated Protein Kinase ◽  
Transformed Cells ◽  
3T3 Cells ◽  
Stress Kinases ◽  
Mitogen Activated Protein ◽  
Stress Kinase ◽  
Transformed Cell Lines ◽  
Nih 3T3 ◽  
Nih 3T3 Cells

ABSTRACT Many primary tumors as well as transformed cell lines display high sensitivity to chemotherapeutic drugs and radiation. The molecular mechanisms that underlie this sensitivity are largely unknown. Here we show that the sensitization of transformed cells to stress stimuli is due to the potentiation of the c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase pathways. Activation of these pathways by the antitumor drug cis-platin (CDDP) and by other stress agents is markedly enhanced and is induced by lower stress doses in NIH 3T3 cells overexpressing epidermal growth factor receptor, HER1–2 kinase, or oncogenic Ras than in nontransformed NIH 3T3 cells. Inhibition of stress kinase activity by specific inhibitors reduces CDDP-mediated cell death in transformed cells, whereas overactivation of stress kinase pathways augments cells death. Potentiation of stress kinases is a common feature of cells transformed by different oncogenes, including cells derived from human tumors, and is shown here to be independent of the activity of the particular transforming oncoprotein. We further show that the mechanism that underlies potentiation of stress kinases in transformed cells involves reactive oxygen species (ROS), whose production is elevated in these cells. JNK/p38 activation is inhibited by antioxidants and in particular by inhibitors of the mitochondrial respiratory chain and NADPH oxidase. Conversely, by artificially elevating ROS levels in nontransformed NIH 3T3 cells we were able to induce potentiation of JNK/p38 activation. Taken together, our findings suggest that ROS-dependent potentiation of stress kinase pathways accounts for the sensitization of transformed cells to stress and anticancer drugs.

scholarly journals Mas Oncogene Signaling and Transformation Require the Small GTP-Binding Protein Rac

1998 ◽  
Vol 18 (3) ◽  
pp. 1225-1235 ◽  
Author(s):  
Irene E. Zohn ◽  
Marc Symons ◽  
Magdalena Chrzanowska-Wodnicka ◽  
John K. Westwick ◽  
Channing J. Der
Keyword(s):  
Cyclin D1 ◽  
Signaling Pathways ◽  
G Protein ◽  
Serum Response Factor ◽  
Dominant Negative ◽  
3T3 Cells ◽  
Rho Family ◽  
Nih 3T3 ◽  
G Protein Coupled ◽  
Nih 3T3 Cells

ABSTRACT The Mas oncogene encodes a novel G-protein-coupled receptor that was identified originally as a transforming protein when overexpressed in NIH 3T3 cells. The mechanism and signaling pathways that mediate Mas transformation have not been determined. We observed that the foci of transformed NIH 3T3 cells caused by Mas were similar to those caused by activated Rho and Rac proteins. Therefore, we determined if Mas signaling and transformation are mediated through activation of a specific Rho family protein. First, we observed that, like activated Rac1, Mas cooperated with activated Raf and caused synergistic transformation of NIH 3T3 cells. Second, both Mas- and Rac1-transformed NIH 3T3 cells retained actin stress fibers and showed enhanced membrane ruffling. Third, like Rac, Mas induced lamellipodium formation in porcine aortic endothelial cells. Fourth, Mas and Rac1 strongly activated the JNK and p38, but not ERK, mitogen-activated protein kinases. Fifth, Mas and Rac1 stimulated transcription from common DNA promoter elements: NF-κB, serum response factor (SRF), Jun/ATF-2, and the cyclin D1 promoter. Finally, Mas transformation and some of Mas signaling (SRF and cyclin D1 but not NF-κB activation) were blocked by dominant negative Rac1. Taken together, these observations suggest that Mas transformation is mediated in part by activation of Rac-dependent signaling pathways. Thus, Rho family proteins are common mediators of transformation by a diverse variety of oncogene proteins that include Ras, Dbl family, and G-protein-coupled oncogene proteins.

Sign in / Sign up

Export Citation Format

Share Document