The transcription factor E2F-1 mediates the autoregulation of RB gene expression

1994 ◽  
Vol 14 (1) ◽  
pp. 299-309
Author(s):  
B Shan ◽  
C Y Chang ◽  
D Jones ◽  
W H Lee
Keyword(s):  
Promoter Region ◽  
Promoter Activity ◽  
Cell Cycle Progression ◽  
Gene Mutations ◽  
Suppressor Gene ◽  
Recognition Sequence ◽  
Cycle Progression ◽  
Rb Gene ◽  
Transcription Factor E2f ◽  
Stimulation Of

The retinoblastoma (RB) gene is the prototype tumor suppressor gene. Mutations in this gene are often associated with the occurrence of various tumors. Several mutations have been found in the promoter region of the gene, suggesting that inappropriate transcriptional regulation of the RB gene contributes to tumorigenesis. Sequence analysis of the RB promoter has revealed a potential E2F recognition site within a region critical for RB gene transcription. By using the cloned E2F-1 gene, here we report that (i) RB expression is negatively regulated by its own gene product, (ii) E2F-1 binds specifically to an E2F recognition sequence in the RB promoter and transactivates the RB promoter, (iii) overexpression of RB suppresses E2F-1-mediated stimulation of RB promoter activity, and (iv) the expression of the RB gene is paralleled by the expression of the E2F-1 gene during cell cycle progression. These results demonstrate that expression of RB is negatively autoregulated through E2F-1.

scholarly journals The transcription factor E2F-1 mediates the autoregulation of RB gene expression.

1994 ◽  
Vol 14 (1) ◽  
pp. 299-309 ◽  
Author(s):  
B Shan ◽  
C Y Chang ◽  
D Jones ◽  
W H Lee
Keyword(s):  
Promoter Region ◽  
Promoter Activity ◽  
Cell Cycle Progression ◽  
Gene Mutations ◽  
Suppressor Gene ◽  
Recognition Sequence ◽  
Cycle Progression ◽  
Rb Gene ◽  
Transcription Factor E2f ◽  
Stimulation Of

The retinoblastoma (RB) gene is the prototype tumor suppressor gene. Mutations in this gene are often associated with the occurrence of various tumors. Several mutations have been found in the promoter region of the gene, suggesting that inappropriate transcriptional regulation of the RB gene contributes to tumorigenesis. Sequence analysis of the RB promoter has revealed a potential E2F recognition site within a region critical for RB gene transcription. By using the cloned E2F-1 gene, here we report that (i) RB expression is negatively regulated by its own gene product, (ii) E2F-1 binds specifically to an E2F recognition sequence in the RB promoter and transactivates the RB promoter, (iii) overexpression of RB suppresses E2F-1-mediated stimulation of RB promoter activity, and (iv) the expression of the RB gene is paralleled by the expression of the E2F-1 gene during cell cycle progression. These results demonstrate that expression of RB is negatively autoregulated through E2F-1.

scholarly journals The NF2 Tumor Suppressor Gene Product, Merlin, Inhibits Cell Proliferation and Cell Cycle Progression by Repressing Cyclin D1 Expression

2005 ◽  
Vol 25 (6) ◽  
pp. 2384-2394 ◽  
Author(s):  
Guang-Hui Xiao ◽  
Ryan Gallagher ◽  
Justin Shetler ◽  
Kristine Skele ◽  
Deborah A. Altomare ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Tumor Suppressor ◽  
Cyclin D1 ◽  
Tumor Suppressor Gene ◽  
Promoter Activity ◽  
Cell Cycle Progression ◽  
Malignant Tumors ◽  
Suppressor Gene ◽  
Cycle Progression

ABSTRACT Inactivation of the NF2 tumor suppressor gene has been observed in certain benign and malignant tumors. Recent studies have demonstrated that merlin, the product of the NF2 gene, is regulated by Rac/PAK signaling. However, the mechanism by which merlin acts as a tumor suppressor has remained obscure. In this report, we show that adenovirus-mediated expression of merlin in NF2-deficient tumor cells inhibits cell proliferation and arrests cells at G1 phase, concomitant with decreased expression of cyclin D1, inhibition of CDK4 activity, and dephosphorylation of pRB. The effect of merlin on cell cycle progression was partially overridden by ectopic expression of cyclin D1. RNA interference experiments showed that silencing of the endogenous NF2 gene results in upregulation of cyclin D1 and S-phase entry. Furthermore, PAK1-stimulated cyclin D1 promoter activity was repressed by cotransfection of NF2, and PAK activity was inhibited by expression of merlin. Interestingly, the S518A mutant form of merlin, which is refractory to phosphorylation by PAK, was more efficient than the wild-type protein in inhibiting cell cycle progression and in repressing cyclin D1 promoter activity. Collectively, our data indicate that merlin exerts its antiproliferative effect, at least in part, via repression of PAK-induced cyclin D1 expression, suggesting a unifying mechanism by which merlin inactivation might contribute to the overgrowth seen in both noninvasive and malignant tumors.

scholarly journals Targeting RB1 Loss in Cancers

Cancers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 3737
Author(s):  
Paing Linn ◽  
Susumu Kohno ◽  
Jindan Sheng ◽  
Nilakshi Kulathunga ◽  
Hai Yu ◽  
...  
Keyword(s):  
Cell Cycle Progression ◽  
Suppressor Gene ◽  
Therapeutic Approaches ◽  
Neighboring Gene ◽  
Genomic Aberration ◽  
Cycle Progression ◽  
Synthetic Lethal ◽  
Mitotic Kinases ◽  
Promote Cell Cycle Progression ◽  
Almost All

Retinoblastoma protein 1 (RB1) is encoded by a tumor suppressor gene that was discovered more than 30 years ago. Almost all mitogenic signals promote cell cycle progression by braking on the function of RB1 protein through mono- and subsequent hyper-phosphorylation mediated by cyclin-CDK complexes. The loss of RB1 function drives tumorigenesis in limited types of malignancies including retinoblastoma and small cell lung cancer. In a majority of human cancers, RB1 function is suppressed during tumor progression through various mechanisms. The latter gives rise to the acquisition of various phenotypes that confer malignant progression. The RB1-targeted molecules involved in such phenotypic changes are good quarries for cancer therapy. Indeed, a variety of novel therapies have been proposed to target RB1 loss. In particular, the inhibition of a number of mitotic kinases appeared to be synthetic lethal with RB1 deficiency. A recent study focusing on a neighboring gene that is often collaterally deleted together with RB1 revealed a pharmacologically targetable vulnerability in RB1-deficient cancers. Here we summarize current understanding on possible therapeutic approaches targeting functional or genomic aberration of RB1 in cancers.

scholarly journals Protein kinase B/Akt is essential for the insulin- but not progesterone-stimulated resumption of meiosis in Xenopus oocytes

2003 ◽  
Vol 369 (2) ◽  
pp. 227-238 ◽  
Author(s):  
Carsten B. ANDERSEN ◽  
Hiroshi SAKAUE ◽  
Taku NEDACHI ◽  
Kristina S. KOVACINA ◽  
Carol CLAYBERGER ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Cell Cycle Progression ◽  
Time Course ◽  
Xenopus Oocytes ◽  
Northern Blotting ◽  
Dominant Negative ◽  
Cycle Progression ◽  
Reverse Transcription Pcr ◽  
Rapid Activation ◽  
Stimulation Of

In the present study, we have characterized the Xenopus Akt expressed in oocytes from the African clawed frog Xenopus laevis and tested whether its activity is required for the insulin- and progesterone-stimulated resumption of meiosis. A cDNA encoding the Xenopus Akt was isolated and sequenced, and its expression in the Xenopus oocyte was confirmed by reverse transcription PCR and Northern blotting. Using phosphospecific antibodies and enzyme assays, a large and rapid activation of the Xenopus Akt was observed upon insulin stimulation of the oocytes. In contrast, progesterone caused a modest activation of this kinase with a slower time course. To test whether the activation of Akt was required in the stimulation of the resumption of meiosis, we have utilized two independent approaches: a functional dominant negative Akt mutant and an inhibitory monoclonal antibody. Both the mutant Akt, as well as the inhibitory monoclonal antibody, completely blocked the insulin-stimulated resumption of meiosis. In contrast, both treatments only partially inhibited (by approx. 30%) the progesterone-stimulated resumption of meiosis when submaximal doses of this hormone were utilized. These data demonstrate a crucial role for Akt in the insulin-stimulated cell cycle progression of Xenopus oocytes, whereas Akt may have an ancillary function in progesterone signalling.

scholarly journals The jun and fos protein families are both required for cell cycle progression in fibroblasts.

1991 ◽  
Vol 11 (9) ◽  
pp. 4466-4472 ◽  
Author(s):  
K Kovary ◽  
R Bravo
Keyword(s):  
Cell Cycle ◽  
Transcription Factors ◽  
Dna Synthesis ◽  
Cell Cycle Progression ◽  
S Phase ◽  
3T3 Cells ◽  
Cycle Progression ◽  
Serum Stimulation ◽  
Fos Protein ◽  
Stimulation Of

The expression of different members of the Jun and Fos families of transcription factors is rapidly induced following serum stimulation of quiescent fibroblasts. To determine whether these proteins are required for cell cycle progression, we microinjected affinity-purified antibodies directed against c-Fos, FosB, Fra-1, c-Jun, JunB, and JunD, and antibodies that recognize either the Fos or the Jun family of proteins, into Swiss 3T3 cells and determined their effects in cell cycle progression by monitoring DNA synthesis. We found that microinjection of anti-Fos and anti-Jun family antibodies efficiently blocked the entrance to the S phase of serum-stimulated or asynchronously growing cells. However, the antibodies against single members of the Fos family only partially inhibited DNA synthesis. In contrast, all three Jun antibodies prevented DNA synthesis more effectively than did any of the anti-Fos antibodies.

scholarly journals CREB Regulates Cell Cycle Progression through RFC3-PCNA Axis in Acute Myeloid Leukemia

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 881-881
Author(s):  
Hee-Don Chae ◽  
Bryan Mitton ◽  
Kathleen Sakamoto
Keyword(s):  
Cell Cycle ◽  
Acute Myeloid Leukemia ◽  
Promoter Region ◽  
Myeloid Leukemia ◽  
Cell Cycle Progression ◽  
Target Genes ◽  
Conflicts Of Interest ◽  
Nuclear Antigen ◽  
Cycle Progression ◽  
Acute Myeloid

Abstract CREB (cAMP Response Element Binding protein) is a transcription factor overexpressed in normal and neoplastic myelopoiesis and regulates cell cycle progression, although its oncogenic mechanism has not been well characterized. Replication Factor C3 (RFC3), a 38 kDa subunit of the RFC complex, is required for chromatin loading of proliferating cell nuclear antigen (PCNA) which is a sliding clamp platform for recruiting numerous proteins in DNA replication and repair processes. CREB1 expression was coupled with RFC3 expression during the G1/S progression in the KG-1 acute myeloid leukemia (AML) cell line, suggesting that RFC3 and CREB1 might be target genes of E2F, a key transcriptional regulator of the G1/S progression. Though there were two potential E2F binding sites in the RFC3 promoter region, chromatin immunoprecipitation assays provided no evidence for E2F1 binding to the RFC3 promoter, whereas E2F1 could directly act on the CREB1 expression. Treatment with the cyclin-dependent kinase (CDK) inhibitor AT7519 decreased expression of CREB1 and RFC3 as well as well-known E2F target genes such as CCNE1, CCNA2 and CCNB1 in KG-1 cells. These results indicate that CREB1 overexpression, a potentially important prognostic marker in leukemia patients, may be associated with dysregulated CDK-E2F activity in leukemia. There was also a direct correlation between the expression of RFC3 and CREB1 in human AML cell lines as well as in AML cells from patients. CREB interacted directly with the CRE site in RFC3 promoter region. CREB knockdown primarily inhibited G1/S cell cycle transition, decreasing expression of RFC3 as well as PCNA loading onto chromatin. Exogenous expression of RFC3 was sufficient to rescue the impaired G1/S progression and PCNA chromatin loading [Chromatin-bound PCNA-positive cells (%), control vs. CREB-knockdown vs. CREB-knockdown with RFC3 overexpression, 8h after release from mitotic arrest: 66.87 +/– 0.90 vs. 24.77 +/– 0.99 vs. 79.17 +/– 0.12, n=3, p< 0.01, mean +/– SEM] caused by CREB knockdown. Taken together, our results suggest that RFC3 may play a role in neoplastic myelopoiesis by promoting the G1/S progression, and its expression is regulated by CREB. These data provide new insight into CREB-driven regulation of the cell cycle in AML cells, and may contribute to leukemogenesis associated with CREB overexpression. Disclosures No relevant conflicts of interest to declare.

Cyclin-Dependent Kinase Phosphorylation of RUNX1/AML1 on Three Sites Increases Trans-Activation Potency and Stimulates Cell Proliferation.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 3351-3351
Author(s):  
Alan D. Friedman ◽  
Linsheng Zhang ◽  
Florence Bernardin Fried
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Aspartic Acid ◽  
Cell Cycle Progression ◽  
Hematopoietic Cell ◽  
Cyclin D3 ◽  
Cycle Progression ◽  
Inhibition Of Proliferation ◽  
Cdk Phosphorylation ◽  
Stimulation Of

RUNX1/AML1 regulates lineage-specific genes during hematopoiesis and also stimulates G1 cell cycle progression. CBFβ-SMMHC or AML1-ETO dominantly inhibit RUNX1 and slow G1 progression in hematopoietic cell lines or in murine or human marrow progenitors, cdk4, cyclin D2, or c-Myc overcome inhibition of proliferation by these CBF oncoproteins, exogenous RUNX1 stimulates G1 progression, and stimulation of G1 via deletion of p16INK4a or expression of E7 cooperates with CBFβ-SMMHC or TEL-AML1 to induce acute leukemia in mice. Induction of cdk4 or cyclin D3 transcription may underlie stimulation of G1 progression by RUNX1. Remarkably, the C. elegans ortholog of RUNX1, RNT-1, also stimulates G1 progression and couples stem cell proliferation with differentiation. Not only does RUNX1 regulate cell cycle progression, but in addition RUNX1 levels increase as hematopoietic cells progress from G1 to S and from S to G2/M. Within RUNX1, S48, S303, and S424 fit the cdk phosphorylation consensus, (S/T)PX(R/K). Phosphorylation of RUNX1 by cyclin dependent kinases on serine 303 was shown to mediate destabilization of RUNX1 in G2/M. We now find that S48 and S424 are also phosphorylated by cdk1 or cdk6. S48, S303, or S424 phosphopeptide antiserum that we developed specifically recognized kinased GST-RUNX1 and interacted with RUNX1 expressed in 293T cells or in the Ba/F3 hematopoietic cell line. S48 phosphorylation of RUNX1 paralleled total RUNX1 levels during cell cycle progression, S303 was more effectively phosphorylated in G2/M, and S424 in G1. Single, double, and triple mutation to alanine or to the partially phosphomimetic aspartic acid progressively diminished or increased trans-activation, such that the tripleA mutant activated a RUNX1 reporter 5-fold less potently than the tripleD mutant. Aspartic acid does not perfectly mimic serine phosphorylation, as illustrated by the much greater affinity of our antisera for wild-type RUNX1 versus RUNX1(tripleD), suggesting that the biologic effect of RUNX1 cdk phosphorylation is even more significant. The p300 co-activator retained interaction with the tripleA variant. The tripleD RUNX1 mutant rescued Ba/F3 cells from inhibition of proliferation by CBFβ-SMMHC more effectively than the tripleA mutant. Cdk phosphorylation of RUNX1 on three sites increases its ability to active transcription and to stimulate proliferation, potentially coupling entry of stem/progenitors into cycle with induction of genes required for hematopoietic lineage progression, such as those encoding myeloperoxidase, neutrophil elastase, the M-CSF receptor, and PU.1.

scholarly journals Distinct Signaling Pathways Mediate Stimulation of Cell Cycle Progression and Prevention of Apoptotic Cell Death by Estrogen in Rat Pituitary Tumor PR1 Cells

2003 ◽  
Vol 14 (12) ◽  
pp. 5051-5059 ◽  
Author(s):  
Simona Caporali ◽  
Manami Imai ◽  
Lucia Altucci ◽  
Massimo Cancemi ◽  
Silvana Caristi ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Cell Death ◽  
Dna Synthesis ◽  
Cell Survival ◽  
Pituitary Tumor ◽  
Cell Cycle Progression ◽  
Cycle Progression ◽  
Rat Pituitary ◽  
Stimulation Of

Estrogens control cell growth and viability in target cells via an interplay of genomic and extragenomic pathways not yet elucidated. Here, we show evidence that cell proliferation and survival are differentially regulated by estrogen in rat pituitary tumor PR1 cells. Pico- to femtomolar concentrations of 17β-estradiol (E2) are sufficient to foster PR1 cell proliferation, whereas nanomolar concentrations of the same are needed to prevent cell death that occurs at a high rate in these cells in the absence of hormone. Activation of endogenous (PRL) or transfected estrogen-responsive genes occurs at the same, higher concentrations of E2 required to promote cell survival, whereas stimulation of cyclin D3 expression and DNA synthesis occur at lower E2 concentrations. Similarly, the pure antiestrogen ICI 182,780 inhibits estrogen response element-dependent trans-activation and cell death more effectively than cyclin-cdk activity, G1-S transition, or DNA synthesis rate. In antiestrogen-treated and/or estrogen-deprived cells, death is due predominantly to apoptosis. Estrogen-induced cell survival, but not E2-dependent cell cycle progression, can be prevented by an inhibitor of c-Src kinase or by blockade of the mitogen-activated protein kinase kinase/extracellular signal-regulated kinase signaling pathway. These data indicate the coexistence of two distinguishable estrogen signaling pathways in PR1 cells, characterized by different functions and sensitivity to hormones and antihormones.

scholarly journals Silencing Lysine-Specific Histone Demethylase 1 (LSD1) Causes Increased HP1-Positive Chromatin, Stimulation of DNA Repair Processes, and Dysregulation of Proliferation by Chk1 Phosphorylation in Human Endothelial Cells

Cells ◽  
2019 ◽  
Vol 8 (10) ◽  
pp. 1212 ◽  
Author(s):  
Wojtala ◽  
Dąbek ◽  
Rybaczek ◽  
Śliwińska ◽  
Świderska ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Endothelial Cells ◽  
Dna Repair ◽  
Cell Cycle Progression ◽  
Cell Model ◽  
Heterochromatin Protein 1 ◽  
Cycle Progression ◽  
Repair Processes ◽  
Lysine Residues ◽  
Stimulation Of

: The methylation of histone lysine residues modifies chromatin conformation and regulates the expression of genes implicated in cell metabolism. Lysine-specific demethylase 1 (LSD1) is a flavin-dependent monoamine oxidase that can demethylate mono- and dimethylated histone lysines 4 and 9 (H3K4 and H3K9). The removal of methyl groups from the lysine residues of histone and non-histone proteins was found to be an important regulatory factor of cell proliferation. However, its role has not been fully elucidated. In this study, we assessed LSD1-mediated cell cycle progression using a human endothelial cell model. The short hairpin RNA knockdown of LSD1 inhibits the G2/M phase of cell cycle progression by checkpoint kinase 1 (Chk1) phosphorylation (S137). We observed elevated DNA damage, which was consistent with the increased detection of double-strand breaks as well as purines and pyrimidines oxidation, which accompanied the activation of ATR/ATRIP signaling by H2AXS139 phosphorylation. The irreversible pharmacological inhibition of LSD1 by 2-phenylcyclopropylamine (2-PCPA) inactivated its enzymatic activity, causing significant changes in heterochromatin and euchromatin conformation assessed by chromatin assembly factor 1 subunit A (CAF1A) and heterochromatin protein 1 isoform α and γ (HP1α/γ) immunofluorescence analysis. We conclude that the knockdown of LSD1 in endothelial cells leads to increased HP1-positive chromatin, the stimulation of DNA repair processes, and the dysregulation of proliferation machinery.

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