scholarly journals Rac1 is required for cell proliferation and G2/M progression

1997 ◽  
Vol 326 (1) ◽  
pp. 17-20 ◽  
Author(s):  
Kimberly A. MOORE ◽  
Rachna SETHI ◽  
A. Masharn DOANES ◽  
Thomas M. JOHNSON ◽  
John B. PRACYK ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Gene Transfer ◽  
Mammalian Cells ◽  
Growth Arrest ◽  
Dominant Negative ◽  
Multiplicity Of Infection ◽  
Gtp Binding ◽  
Dominant Negative Form ◽  
Negative Form

We have transiently expressed a dominant negative form of rac1 (N17rac1) using adenoviral-mediated gene transfer. The level of N17rac1 expression is demonstrated to be proportional to the multiplicity of infection. Expression of N17rac1 in Rat 2 fibroblasts results in cytostatic growth arrest. Cell-cycle analysis demonstrates that cells expressing N17rac1 accumulate in G2/M. These results suggest that rac1 is required for cell proliferation and provide the first demonstration in mammalian cells of a role for small GTP-binding proteins in the G2/M transition.

The evolutionarily conserved Dim1 protein defines a novel branch of the thioredoxin fold superfamily

1999 ◽  
Vol 1 (3) ◽  
pp. 109-118 ◽  
Author(s):  
YU-ZHU ZHANG ◽  
KATHLEEN L. GOULD ◽  
ROLAND L. DUNBRACK ◽  
HONG CHENG ◽  
HEINRICH RODER ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Mutational Analysis ◽  
Mrna Splicing ◽  
Dominant Negative ◽  
Cycle Arrest ◽  
Dominant Negative Form ◽  
Sequence Homologies ◽  
Evolutionarily Conserved ◽  
Carboxy Terminal ◽  
Negative Form

Zhang, Yu-Zhu, Kathleen L. Gould, Roland L. Dunbrack, Jr., Hong Cheng, Heinrich Roder, and Erica A. Golemis. The evolutionarily conserved Dim1 protein defines a novel branch of the thioredoxin fold superfamily. Physiol. Genomics 1: 109–118, 1999.—Dim1 is a small evolutionarily conserved protein essential for G2/M transition that has recently been implicated as a component of the mRNA splicing machinery. To date, the mechanism of Dim1 function remains poorly defined, in part because of the absence of informative sequence homologies between Dim1 and other functionally defined proteins or protein domains. We have used a combination of molecular modeling and NMR structural analysis to demonstrate that ∼125 of the 142 amino acids of human Dim1 (hDim1) define a novel branch of the thioredoxin fold superfamily. Mutational analysis of Dim1 based on the predicted fold indicates that alterations in the region corresponding to the thioredoxin active site do not affect Dim1 activity. However, removal of a very short carboxy-terminal extension generates a dominant negative form of the protein [hDim1-(1–128)] that when overproduced induces cell cycle arrest in G2, via a mechanism likely to involve alteration of Dim1 association with partner molecules. In sum, this study identifies the Dim1 proteins as a novel sixth branch of the thioredoxin superfamily involved in cell cycle.

scholarly journals Mammalian WDR12 is a novel member of the Pes1–Bop1 complex and is required for ribosome biogenesis and cell proliferation

2005 ◽  
Vol 170 (3) ◽  
pp. 367-378 ◽  
Author(s):  
Michael Hölzel ◽  
Michaela Rohrmoser ◽  
Martin Schlee ◽  
Thomas Grimm ◽  
Thomas Harasim ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Mammalian Cells ◽  
Ribosome Biogenesis ◽  
Target Genes ◽  
Dominant Negative ◽  
Stable Complex ◽  
Dominant Negative Mutant ◽  
Proliferating Cells ◽  
Independent Manner

Target genes of the protooncogene c-myc are implicated in cell cycle and growth control, yet the linkage of both is still unexplored. Here, we show that the products of the nucleolar target genes Pes1 and Bop1 form a stable complex with a novel member, WDR12 (PeBoW complex). Endogenous WDR12, a WD40 repeat protein, is crucial for processing of the 32S precursor ribosomal RNA (rRNA) and cell proliferation. Further, a conditionally expressed dominant-negative mutant of WDR12 also blocks rRNA processing and induces a reversible cell cycle arrest. Mutant WDR12 triggers accumulation of p53 in a p19ARF-independent manner in proliferating cells but not in quiescent cells. Interestingly, a potential homologous complex of Pes1–Bop1–WDR12 in yeast (Nop7p–Erb1p–Ytm1p) is involved in the control of ribosome biogenesis and S phase entry. In conclusion, the integrity of the PeBoW complex is required for ribosome biogenesis and cell proliferation in mammalian cells.

scholarly journals Adenovirus E4orf4 protein induces PP2A-dependent growth arrest in Saccharomyces cerevisiae and interacts with the anaphase-promoting complex/cyclosome

2001 ◽  
Vol 154 (2) ◽  
pp. 331-344 ◽  
Author(s):  
Daniel Kornitzer ◽  
Rakefet Sharf ◽  
Tamar Kleinberger
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Mammalian Cells ◽  
Growth Arrest ◽  
Anaphase Promoting Complex ◽  
Reading Frame ◽  
Cycle Growth ◽  
M Phase ◽  
Dependent Growth ◽  
Synthetically Lethal

Adenovirus early region 4 open reading frame 4 (E4orf4) protein has been reported to induce p53-independent, protein phosphatase 2A (PP2A)–dependent apoptosis in transformed mammalian cells. In this report, we show that E4orf4 induces an irreversible growth arrest in Saccharomyces cerevisiae at the G2/M phase of the cell cycle. Growth inhibition requires the presence of yeast PP2A-Cdc55, and is accompanied by accumulation of reactive oxygen species. E4orf4 expression is synthetically lethal with mutants defective in mitosis, including Cdc28/Cdk1 and anaphase-promoting complex/cyclosome (APC/C) mutants. Although APC/C activity is inhibited in the presence of E4orf4, Cdc28/Cdk1 is activated and partially counteracts the E4orf4-induced cell cycle arrest. The E4orf4–PP2A complex physically interacts with the APC/C, suggesting that E4orf4 functions by directly targeting PP2A to the APC/C, thereby leading to its inactivation. Finally, we show that E4orf4 can induce G2/M arrest in mammalian cells before apoptosis, indicating that E4orf4-induced events in yeast and mammalian cells are highly conserved.

scholarly journals Cooperative effects of genes controlling the G2/M checkpoint

2000 ◽  
Vol 14 (13) ◽  
pp. 1584-1588
Author(s):  
Timothy A. Chan ◽  
Paul M. Hwang ◽  
Heiko Hermeking ◽  
Kenneth W. Kinzler ◽  
Bert Vogelstein
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Mammalian Cells ◽  
Growth Arrest ◽  
Double Knockout ◽  
Specific Test ◽  
Cooperative Effects ◽  
Exogenous Expression ◽  
Induced Genes ◽  
Single Knockout

It is believed that multiple effectors independently control the checkpoints permitting transitions between cell cycle phases. However, this has not been rigorously demonstrated in mammalian cells. The p53-induced genes p21 and 14-3-3ς are each required for the G2 arrest and allow a specific test of this fundamental tenet. We generated human cells deficient in bothp21 and 14-3-3ς and determined whether the double knockout was more sensitive to DNA damage than either single knockout.p21−/−14-3-3ς−/− cells were significantly more sensitive to DNA damage or to the exogenous expression of p53 than cells lacking only p21 or only 14-3-3ς. Thus, p21 and 14-3-3ς play distinct but complementary roles in the G2/M checkpoint, and help explain why genes at the nodal points of growth arrest pathways, like p53, are the targets of mutation in cancer cells.

scholarly journals Jagged1/Notch3 Signaling Modulates Hemangioma-Derived Pericyte Proliferation and Maturation

2016 ◽  
Vol 40 (5) ◽  
pp. 895-907 ◽  
Author(s):  
Yi Ji ◽  
Siyuan Chen ◽  
Bo Xiang ◽  
Yuan Li ◽  
Li Li ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Smooth Muscle ◽  
Smooth Muscle Actin ◽  
Growth Arrest ◽  
Notch Signaling Pathway ◽  
Cell Growth Arrest ◽  
Muscle Myosin ◽  
Dependent Mechanism

Background: The Notch signaling pathway has been implicated in the pericyte phenotype, but its exact roles in hemangioma-derived pericytes (Hem-pericytes) remain ill defined. Methods: Hem-pericytes were stimulated by immobilized recombinant Jagged1. The potential mechanisms of Notch-induced Hem-pericytes growth arrest were investigated by cell cycle assay, and the role of the Notch in promoting Hem-pericyte maturation was also analyzed by real-time PCR and western blot. Results: Activation of Notch3 in Hem-pericytes significantly reduced cell proliferation and inhibited cell cycle transition. This event was associated with an increase in the levels of p21Cip1. Knockdown of p21Cip1 resulted in a significant rescue of Notch-induced cell growth arrest and an entry into the cell cycle. We showed that Jagged1 activation of Notch3 signaling upregulated the expression of the pericyte contractile markers smooth muscle myosin heavy chain (smMHC) and α-smooth muscle actin (αSMA), concomitant with an increase in the expression of myocardin in Hem-pericytes. We further revealed that the endothelial-derived Jagged1 modulated the Hem-pericyte phenotype via a contact-dependent mechanism. Conclusions: Our results demonstrated that Jagged1 activation of Notch3 resulted in a significant decrease in cell proliferation while concomitantly promoting Hem-pericyte maturation. These data provide initial evidence that Notch induces a quiescent phenotype in Hem-pericytes.

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