Transcription of the E2F-1 gene is rendered cell cycle dependent by E2F DNA-binding sites within its promoter

1994 ◽  
Vol 14 (10) ◽  
pp. 6607-6615
Author(s):  
E Neuman ◽  
E K Flemington ◽  
W R Sellers ◽  
W G Kaelin

The cell cycle-regulatory transcription factor E2F-1 is regulated by interactions with proteins such as the retinoblastoma gene product and by cell cycle-dependent alterations in E2F-1 mRNA abundance. To better understand this latter phenomenon, we have isolated the human E2F-1 promoter. The human E2F-1 promoter, fused to a luciferase cDNA, gave rise to cell cycle-dependent luciferase activity upon transfection into mammalian cells in a manner which paralleled previously reported changes in E2F-1 mRNA abundance. The E2F-1 promoter contains four potential E2F-binding sites organized as two imperfect palindromes. Gel shift and transactivation studies suggested that these sites can bind to E2F in vitro and in vivo. Mutation of the two E2F palindromes abolished the cell cycle dependence of the E2F-1 promoter. Thus, E2F-1 appears to be regulated at the level of transcription, and this regulation is due, at least in part, to binding of one or more E2F family members to the E2F-1 promoter.

1994 ◽  
Vol 14 (10) ◽  
pp. 6607-6615 ◽  
Author(s):  
E Neuman ◽  
E K Flemington ◽  
W R Sellers ◽  
W G Kaelin

The cell cycle-regulatory transcription factor E2F-1 is regulated by interactions with proteins such as the retinoblastoma gene product and by cell cycle-dependent alterations in E2F-1 mRNA abundance. To better understand this latter phenomenon, we have isolated the human E2F-1 promoter. The human E2F-1 promoter, fused to a luciferase cDNA, gave rise to cell cycle-dependent luciferase activity upon transfection into mammalian cells in a manner which paralleled previously reported changes in E2F-1 mRNA abundance. The E2F-1 promoter contains four potential E2F-binding sites organized as two imperfect palindromes. Gel shift and transactivation studies suggested that these sites can bind to E2F in vitro and in vivo. Mutation of the two E2F palindromes abolished the cell cycle dependence of the E2F-1 promoter. Thus, E2F-1 appears to be regulated at the level of transcription, and this regulation is due, at least in part, to binding of one or more E2F family members to the E2F-1 promoter.


1997 ◽  
Vol 17 (12) ◽  
pp. 6994-7007 ◽  
Author(s):  
Y Tao ◽  
R F Kassatly ◽  
W D Cress ◽  
J M Horowitz

The product of the retinoblastoma (Rb) susceptibility gene, Rb-1, regulates the activity of a wide variety of transcription factors, such as E2F, in a cell cycle-dependent fashion. E2F is a heterodimeric transcription factor composed of two subunits each encoded by one of two related gene families, denoted E2F and DP. Five E2F genes, E2F-1 through E2F-5, and two DP genes, DP-1 and DP-2, have been isolated from mammals, and heterodimeric complexes of these proteins are expressed in most, if not all, vertebrate cells. It is not yet clear whether E2F/DP complexes regulate overlapping and/or specific cellular genes. Moreover, little is known about whether Rb regulates all or a subset of E2F-dependent genes. Using recombinant E2F, DP, and Rb proteins prepared in baculovirus-infected cells and a repetitive immunoprecipitation-PCR procedure (CASTing), we have identified consensus DNA-binding sites for E2F-1/DP-1, E2F-1/DP-2, E2F-4/DP-1, and E2F-4/DP-2 complexes as well as an Rb/E2F-1/DP-1 trimeric complex. Our data indicate that (i) E2F, DP, and Rb proteins each influence the selection of E2F-binding sites; (ii) E2F sites differ with respect to their intrinsic DNA-bending properties; (iii) E2F/DP complexes induce distinct degrees of DNA bending; and (iv) complex-specific E2F sites selected in vitro function distinctly as regulators of cell cycle-dependent transcription in vivo. These data indicate that the specific sequence of an E2F site may determine its role in transcriptional regulation and suggest that Rb/E2F complexes may regulate subsets of E2F-dependent cellular genes.


1996 ◽  
Vol 16 (4) ◽  
pp. 1659-1667 ◽  
Author(s):  
J Karlseder ◽  
H Rotheneder ◽  
E Wintersberger

Within the region around 150 bp upstream of the initiation codon, which was previously shown to suffice for growth-regulated expression, the murine thymidine kinase gene carries a single binding site for transcription factor Sp1; about 10 bp downstream of this site, there is a binding motif for transcription factor E2F. The latter protein appears to be responsible for growth regulation of the promoter. Mutational inactivation of either the Sp1 or the E2F site almost completely abolishes promoter activity, suggesting that the two transcription factors interact directly in delivering an activation signal to the basic transcription machinery. This was verified by demonstrating with the use of glutathione S-transferase fusion proteins that E2F and Sp1 bind to each other in vitro. For this interaction, the C-terminal part of Sp1 and the N terminus of E2F1, a domain also present in E2F2 and E2F3 but absent in E2F4 and E2F5, were essential. Accordingly, E2F1 to E2F3 but not E2F4 and E2F5 were found to bind sp1 in vitro. Coimmunoprecipitation experiments showed that complexes exist in vivo, and it was estabilished that the distance between the binding sites for the two transcription factors was critical for optimal promoter activity. Finally, in vivo footprinting experiments indicated that both the sp1 and E2F binding sites are occupied throughout the cell cycle. Mutation of either binding motif abolished binding of both transcription factors in vivo, which may indicate cooperative binding of the two proteins to chromatin-organized DNA. Our data are in line with the hypothesis that E2F functions as a growth- and cell cycle regulated tethering factor between Sp1 and the basic transcription machinery.


2004 ◽  
Vol 3 (5) ◽  
pp. 1185-1197 ◽  
Author(s):  
Bidyottam Mittra ◽  
Dan S. Ray

ABSTRACT Crithidia fasciculata cycling sequence binding proteins (CSBP) have been shown to bind with high specificity to sequence elements present in several mRNAs that accumulate periodically during the cell cycle. The first described CSBP has subunits of 35.6 (CSBPA) and 42 kDa (CSBPB). A second distinct binding protein termed CSBP II has been purified from CSBPA null mutant cells, lacking both CSBPA and CSBPB proteins, and contains three major polypeptides with predicted molecular masses of 63, 44.5, and 33 kDa. Polypeptides of identical size were radiolabeled in UV cross-linking assays performed with purified CSBP II and 32P-labeled RNA probes containing six copies of the cycling sequence. The CSBP II binding activity was found to cycle in parallel with target mRNA levels during progression through the cell cycle. We have cloned genes encoding these three CSBP II proteins, termed RBP63, RBP45, and RBP33, and characterized their binding properties. The RBP63 protein is a member of the poly(A) binding protein family. Homologs of RBP45 and RBP33 proteins were found only among the kinetoplastids. Both RBP45 and RBP33 proteins and their homologs have a conserved carboxy-terminal half that contains a PSP1-like domain. All three CSBP II proteins show specificity for binding the wild-type cycling sequence in vitro. RBP45 and RBP33 are phosphoproteins, and RBP45 has been found to bind in vivo specifically to target mRNA containing cycling sequences. The levels of phosphorylation of both RBP45 and RBP33 were found to cycle during the cell cycle.


2018 ◽  
Vol 115 (16) ◽  
pp. E3692-E3701 ◽  
Author(s):  
Chaitanya Rastogi ◽  
H. Tomas Rube ◽  
Judith F. Kribelbauer ◽  
Justin Crocker ◽  
Ryan E. Loker ◽  
...  

Transcription factors (TFs) control gene expression by binding to genomic DNA in a sequence-specific manner. Mutations in TF binding sites are increasingly found to be associated with human disease, yet we currently lack robust methods to predict these sites. Here, we developed a versatile maximum likelihood framework named No Read Left Behind (NRLB) that infers a biophysical model of protein-DNA recognition across the full affinity range from a library of in vitro selected DNA binding sites. NRLB predicts human Max homodimer binding in near-perfect agreement with existing low-throughput measurements. It can capture the specificity of the p53 tetramer and distinguish multiple binding modes within a single sample. Additionally, we confirm that newly identified low-affinity enhancer binding sites are functional in vivo, and that their contribution to gene expression matches their predicted affinity. Our results establish a powerful paradigm for identifying protein binding sites and interpreting gene regulatory sequences in eukaryotic genomes.


2017 ◽  
Author(s):  
Luca Tosti ◽  
James Ashmore ◽  
Boon Siang Nicholas Tan ◽  
Benedetta Carbone ◽  
Tapan K Mistri ◽  
...  

AbstractThe identification of transcription factor (TF) binding sites in the genome is critical to understanding gene regulatory networks (GRNs). While ChIP-seq is commonly used to identify TF targets, it requires specific ChIP-grade antibodies and high cell numbers, often limiting its applicability. DNA adenine methyltransferase identification (DamID), developed and widely used in Drosophila, is a distinct technology to investigate protein-DNA interactions. Unlike ChIP-seq, it does not require antibodies, precipitation steps or chemical protein-DNA crosslinking, but to date it has been seldom used in mammalian cells due to technical impediments. Here we describe an optimised DamID method coupled with next generation sequencing (DamID-seq) in mouse cells, and demonstrate the identification of the binding sites of two TFs, OCT4 and SOX2, in as few as 1,000 embryonic stem cells (ESCs) and neural stem cells (NSCs), respectively. Furthermore, we have applied this technique in vivo for the first time in mammals. Oct4 DamID-seq in the gastrulating mouse embryo at 7.5 days post coitum (dpc) successfully identified multiple Oct4 binding sites proximal to genes involved in embryo development, neural tube formation, mesoderm-cardiac tissue development, consistent with the pivotal role of this TF in post-implantation embryo. This technology paves the way to unprecedented investigations of TF-DNA interactions and GRNs in specific cell types with limited availability in mammals including in vivo samples.


2001 ◽  
Vol 21 (19) ◽  
pp. 6484-6494 ◽  
Author(s):  
Laurence Vandel ◽  
Estelle Nicolas ◽  
Olivier Vaute ◽  
Roger Ferreira ◽  
Slimane Ait-Si-Ali ◽  
...  

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.


1993 ◽  
Vol 13 (12) ◽  
pp. 7469-7475 ◽  
Author(s):  
C Chang ◽  
J D Gralla

Transcription associated with a terminal deoxynucleotide transferase gene initiator element is shown to respond to the transcription factor GAL4-VP16 both in vivo and in vitro. High-level transcription requires both an intact initiator element and bound activator. Transcription from this initiator-directed promoter is synergistic in vivo in that five GAL4 DNA binding sites yield 36 times the expression of a single site. Promoters dominated by initiator and TATA elements respond similarly to several GAL4-based activators, including GAL4-Sp1, GAL4-CTF, GAL4(1-147), GAL4-p53, GAL4-C/EBP, and GAL4-ER(EF), as well as GAL4-VP16 and Sp1. These and other similarities suggest that primary activation of TATA- and initiator-dominated promoters occurs at common steps. Since the initial assembly steps do not appear to be common for the two promoter types, the results place interesting constraints on models for how activation occurs.


2002 ◽  
Vol 13 (6) ◽  
pp. 2016-2030 ◽  
Author(s):  
Mitsuru Okuwaki ◽  
Masafumi Tsujimoto ◽  
Kyosuke Nagata

Nucleophosmin/B23 is a nucleolar phosphoprotein. It has been shown that B23 binds to nucleic acids, digests RNA, and is localized in nucleolar granular components from which preribosomal particles are transported to cytoplasm. The intracellular localization of B23 is significantly changed during the cell cycle. Here, we have examined the cellular localization of B23 proteins and the effect of mitotic phosphorylation of B23.1 on its RNA binding activity. Two splicing variants of B23 proteins, termed B23.1 and B23.2, were complexed both in vivo and in vitro. The RNA binding activity of B23.1 was impaired by hetero-oligomer formation with B23.2. Both subtypes of B23 proteins were phosphorylated during mitosis by cyclin B/cdc2. The RNA binding activity of B23.1 was repressed through cyclin B/cdc2-mediated phosphorylation at specific sites in B23. Thus, the RNA binding activity of B23.1 is stringently modulated by its phosphorylation and subtype association. Interphase B23.1 was mainly localized in nucleoli, whereas B23.2 and mitotic B23.1, those of which were incapable of binding to RNA, were dispersed throughout the nucleoplasm and cytoplasm, respectively. These results suggest that nucleolar localization of B23.1 is mediated by its ability to associate with RNA.


2010 ◽  
Vol 428 (1) ◽  
pp. 103-111 ◽  
Author(s):  
Pierre-Luc Tanguay ◽  
Geneviève Rodier ◽  
Sylvain Meloche

ERK3 (extracellular-signal-regulated kinase 3) is an atypical MAPK (mitogen-activated protein kinase) that is suggested to play a role in cell-cycle progression and cellular differentiation. However, it is not known whether the function of ERK3 is regulated during the cell cycle. In the present paper, we report that ERK3 is stoichiometrically hyperphosphorylated during entry into mitosis and is dephosphorylated at the M→G1 transition. The phosphorylation of ERK3 is associated with the accumulation of the protein in mitosis. In vitro phosphorylation of a series of ERK3-deletion mutants by mitotic cell extracts revealed that phosphorylation is confined to the unique C-terminal extension of the protein. Using MS analysis, we identified four novel phosphorylation sites, Ser684, Ser688, Thr698 and Ser705, located at the extreme C-terminus of ERK3. All four sites are followed by a proline residue. We have shown that purified cyclin B-Cdk1 (cyclindependent kinase 1) phosphorylates these sites in vitro and demonstrate that Cdk1 acts as a major Thr698 kinase in vivo. Reciprocally, we found that the phosphatases Cdc14A and Cdc14B (Cdc is cell-division cycle) bind to ERK3 and reverse its C-terminal phosphorylation in mitosis. Importantly, alanine substitution of the four C-terminal phosphorylation sites markedly decreased the half-life of ERK3 in mitosis, thereby linking phosphorylation to the stabilization of the kinase. The results of the present study identify a novel regulatory mechanism of ERK3 that operates in a cell-cycle-dependent manner.


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