An E2F-binding site mediates the activation of the proliferative isoform of 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase by phosphatidylinositol 3-kinase

In the present study, we demonstrate that E2F is implicated in the regulation of the glycolytic enzyme 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (6PF2K/Fru-2,6-BPase) during cell division. The expression of this enzyme is induced during the G1/S transition of the cell cycle. We identified and monitored the E2F-pocket protein complexes that bind to the E2F site of the F-type promoter during cell-cycle entry, and we analysed their contribution to the phosphatidylinositol 3-kinase (PI 3-kinase)-mediated regulation of the promoter. We found that the predominant E2F complex bound to the F-type promoter in unstimulated/quiescent cells contains E2F4, DP1 and p130 proteins. In serum-stimulated (S-phase) cells, the composition of the complex switched to E2F1/4, DP1 and p107, together with cyclin A and cyclin-dependent kinase 2. Treatment with the PI 3-kinase specific inhibitor LY 294002 prevented the formation of the S-phase complex, suggesting that activation of the PI 3-kinase pathway is essential for the formation of this complex. Further supporting this idea, we obtained results showing that treatment of cycling NIH 3T3 cells with either wortmannin or LY 294002 induces the accumulation of the transcriptionally repressive p130—E2F4—DP1 complex. Using the Rat-1 ER—E2F1 cell line where E2F1 activity can be conditionally induced, we demonstrated that E2F activity is involved in the in vivo transcriptional regulation of the F-type 6PF2K/Fru-2,6-BPase gene. Taken together, our results show that the F-type 6PF2K/Fru-2,6-BPase is a genuine E2F-regulated gene, and that its regulation by the PI 3-kinase pathway is at least partially mediated through the E2F transcription factor.

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c-Cbl Is Tyrosine-Phosphorylated by Interleukin-4 and Enhances Mitogenic and Survival Signals of Interleukin-4 Receptor by Linking With the Phosphatidylinositol 3′-Kinase Pathway

Blood ◽

10.1182/blood.v91.1.46.46_46_53 ◽

1998 ◽

Vol 91 (1) ◽

pp. 46-53 ◽

Cited By ~ 7

Author(s):

Hiroo Ueno ◽

Ko Sasaki ◽

Hiroaki Honda ◽

Tetsuya Nakamoto ◽

Tetsuya Yamagata ◽

...

Keyword(s):

Specific Inhibitor ◽

Pi3 Kinase ◽

Interleukin 4 ◽

Phosphatidylinositol 3 Kinase ◽

Proliferation And Differentiation ◽

Interleukin 4 Receptor ◽

Pi3 Kinase Pathway ◽

Kinase Pathway ◽

Phosphatidylinositol 3 ◽

Survival Signals

Interleukin-4 (IL-4) is a cytokine that induces both proliferation and differentiation and suppresses apoptosis of B cells. Although IL-4 has been shown to activate the phosphatidylinositol 3′ (PI3)-kinase pathway, the role of PI3 kinase in the IL-4 receptor (IL-4R) signaling remains unclear. In this study, we demonstrated that c-Cbl proto-oncogene product is inducibly phosphorylated on tyrosine residues and is associated with the p85 subunit of PI3-kinase by IL-4 stimulation. Overexpression of c-Cbl enhances the PI3-kinase activity and, at the same time, mitogenic activity and survival of cells in the presence of IL-4. However, these effects of c-Cbl were abolished by wortmannin, a specific inhibitor for the PI3 kinase pathway, or by a point mutation at tyrosine 731 of c-Cbl, which is a major binding site for p85. These results indicate that c-Cbl plays a role in linking IL-4R with the PI3 kinase pathway and thus enhancing the mitogenic and survival signals.

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Transcriptional Repression by the Retinoblastoma Protein through the Recruitment of a Histone Methyltransferase

Molecular and Cellular Biology ◽

10.1128/mcb.21.19.6484-6494.2001 ◽

2001 ◽

Vol 21 (19) ◽

pp. 6484-6494 ◽

Cited By ~ 124

Author(s):

Laurence Vandel ◽

Estelle Nicolas ◽

Olivier Vaute ◽

Roger Ferreira ◽

Slimane Ait-Si-Ali ◽

...

Keyword(s):

Cell Cycle ◽

Transcriptional Repression ◽

Histone Deacetylases ◽

Histone H3 ◽

Histone Methyltransferase ◽

S Phase ◽

E2f Transcription Factor ◽

Cycle Dependent

ABSTRACT The E2F transcription factor controls the cell cycle-dependent expression of many S-phase-specific genes. Transcriptional repression of these genes in G0 and at the beginning of G1by the retinoblasma protein Rb is crucial for the proper control of cell proliferation. Rb has been proposed to function, at least in part, through the recruitment of histone deacetylases. However, recent results indicate that other chromatin-modifying enzymes are likely to be involved. Here, we show that Rb also interacts with a histone methyltransferase, which specifically methylates K9 of histone H3. The results of coimmunoprecipitation experiments of endogenous or transfected proteins indicate that this histone methyltransferase is the recently described heterochromatin-associated protein Suv39H1. Interestingly, phosphorylation of Rb in vitro as well as in vivo abolished the Rb-Suv39H1 interaction. We also found that Suv39H1 and Rb cooperate to repress E2F activity and that Suv39H1 could be recruited to E2F1 through its interaction with Rb. Taken together, these data indicate that Suv39H1 is involved in transcriptional repression by Rb and suggest an unexpected link between E2F regulation and heterochromatin.

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c-Cbl Is Tyrosine-Phosphorylated by Interleukin-4 and Enhances Mitogenic and Survival Signals of Interleukin-4 Receptor by Linking With the Phosphatidylinositol 3′-Kinase Pathway

Blood ◽

10.1182/blood.v91.1.46 ◽

1998 ◽

Vol 91 (1) ◽

pp. 46-53 ◽

Cited By ~ 56

Author(s):

Hiroo Ueno ◽

Ko Sasaki ◽

Hiroaki Honda ◽

Tetsuya Nakamoto ◽

Tetsuya Yamagata ◽

...

Keyword(s):

Specific Inhibitor ◽

Pi3 Kinase ◽

Interleukin 4 ◽

Phosphatidylinositol 3 Kinase ◽

Proliferation And Differentiation ◽

Interleukin 4 Receptor ◽

Pi3 Kinase Pathway ◽

Kinase Pathway ◽

Phosphatidylinositol 3 ◽

Survival Signals

Abstract Interleukin-4 (IL-4) is a cytokine that induces both proliferation and differentiation and suppresses apoptosis of B cells. Although IL-4 has been shown to activate the phosphatidylinositol 3′ (PI3)-kinase pathway, the role of PI3 kinase in the IL-4 receptor (IL-4R) signaling remains unclear. In this study, we demonstrated that c-Cbl proto-oncogene product is inducibly phosphorylated on tyrosine residues and is associated with the p85 subunit of PI3-kinase by IL-4 stimulation. Overexpression of c-Cbl enhances the PI3-kinase activity and, at the same time, mitogenic activity and survival of cells in the presence of IL-4. However, these effects of c-Cbl were abolished by wortmannin, a specific inhibitor for the PI3 kinase pathway, or by a point mutation at tyrosine 731 of c-Cbl, which is a major binding site for p85. These results indicate that c-Cbl plays a role in linking IL-4R with the PI3 kinase pathway and thus enhancing the mitogenic and survival signals.

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ZSTK474, a specific phosphatidylinositol 3-kinase inhibitor, induces G1 arrest of the cell cycle in vivo

European Journal of Cancer ◽

10.1016/j.ejca.2011.10.006 ◽

2012 ◽

Vol 48 (6) ◽

pp. 936-943 ◽

Cited By ~ 26

Author(s):

Shingo Dan ◽

Mutsumi Okamura ◽

Yumiko Mukai ◽

Hisashi Yoshimi ◽

Yasumichi Inoue ◽

...

Keyword(s):

Cell Cycle ◽

Kinase Inhibitor ◽

G1 Arrest ◽

Phosphatidylinositol 3 Kinase ◽

Phosphatidylinositol 3

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Requirement of phosphatidylinositol 3-kinase-dependent pathway and Src for Gas6-Axl mitogenic and survival activities in NIH 3T3 fibroblasts.

Molecular and Cellular Biology ◽

10.1128/mcb.17.8.4442 ◽

1997 ◽

Vol 17 (8) ◽

pp. 4442-4453 ◽

Cited By ~ 135

Author(s):

S Goruppi ◽

E Ruaro ◽

B Varnum ◽

C Schneider

Keyword(s):

Tyrosine Kinase ◽

Specific Inhibitor ◽

S Phase ◽

Phosphatidylinositol 3 Kinase ◽

3T3 Cells ◽

Src Tyrosine Kinase ◽

Survival Effect ◽

Nih 3T3 ◽

Nih 3T3 Cells ◽

Phosphatidylinositol 3

Gas6 is a secreted protein previously identified as the ligand of the Axl receptor tyrosine kinase. We have shown that Gas6 is able to induce cell cycle reentry of serum-starved NIH 3T3 cells and to efficiently prevent apoptosis after complete growth factor removal, a survival effect uncoupled from Gas6-induced mitogenesis. Here we report that the mitogenic effect of Gas6 requires phosphatidylinositol 3-kinase (PI3K) activity since it is abrogated both by the specific inhibitor wortmannin and by overexpression of the dominant negative P13K p85 subunit. Consistently, Gas6 activates the P13K downstream targets S6K and Akt, whose activation is abrogated by addition of wortmannin. Moreover, rapamycin treatment blocks Gas6-induced entry into the S phase of serum-starved NIH 3T3 cells. We also demonstrate the requirement of Src tyrosine kinase for Gas6 signalling since stable or transient expression of a catalytically inactive form of Src significantly inhibited Gas6-stimulated entry into the S phase. Accordingly, Gas6 addition to serum-starved NIH 3T3 cells causes activation of the intrinsic Src kinase activity. When specifically analyzed in a survival assay, these elements were found to be required for the survival effect of Gas6. Taken together, the evidence presented here identifies elements involved in the Gas6 transduction pathway that are responsible for its antiapoptotic effect and suggests that Src is involved in the events regulating cell survival.

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Activation of Phosphatidylinositol 3-Kinase Is Sufficient for Cell Cycle Entry and Promotes Cellular Changes Characteristic of Oncogenic Transformation

Molecular and Cellular Biology ◽

10.1128/mcb.18.10.5699 ◽

1998 ◽

Vol 18 (10) ◽

pp. 5699-5711 ◽

Cited By ~ 181

Author(s):

Anke Klippel ◽

Maria-Amelia Escobedo ◽

Matthew S. Wachowicz ◽

Gerald Apell ◽

Timothy W. Brown ◽

...

Keyword(s):

Cell Cycle ◽

Cell Growth ◽

Soft Agar ◽

S Phase ◽

Oncogenic Transformation ◽

Phosphatidylinositol 3 Kinase ◽

Kinase Activation ◽

Serum Stimulation ◽

Cellular Changes ◽

Phosphatidylinositol 3

ABSTRACT Using a new inducible form of phosphatidylinositol 3-kinase (PI 3-kinase) we have found that PI 3-kinase activation has the following effects on cell growth and proliferation. (i) Activation of PI 3-kinase was sufficient to promote entry into S phase of the cell cycle within several hours. This was shown by activation of cyclin-dependent kinase 4 (Cdk4) and Cdk2 and by the induction of DNA synthesis. (ii) PI 3-kinase activation alone was not, however, sufficient to provide for progression through the entire cell cycle. Instead, prolonged activation of PI 3-kinase in the absence of serum stimulation resulted in apoptosis. It is possible that the cells undergo apoptosis because the PI 3-kinase-induced entry into the cell cycle is abnormal. For example, we found that the cyclin E-Cdk2 complex, which normally disappears after entry into S phase of the cell cycle, fails to be downregulated following induction by PI 3-kinase. (iii) Finally, we found that prolonged activation of PI 3-kinase in the presence of serum resulted in cellular changes that resemble those associated with oncogenic transformation. The cells reached high densities, were irregular and refractile in appearance, and formed colonies in soft agar. In contrast, neither PI 3-kinase nor serum stimulation alone could induce these changes. Our results suggest that activation of PI 3-kinase promotes anchorage-independent cell growth and entry into the cell cycle but does not abrogate the growth factor requirement for cell proliferation.

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