CTCF function is modulated by neighboring DNA binding factors

2011 ◽  
Vol 89 (5) ◽  
pp. 459-468 ◽  
Author(s):  
Oliver Weth ◽  
Rainer Renkawitz
Keyword(s):  
Dna Binding ◽  
Binding Site ◽  
Zinc Finger ◽  
Binding Sites ◽  
Zinc Finger Protein ◽  
Gene Activation ◽  
Ctcf Binding ◽  
Paternal Allele ◽  
Ctcf Binding Site ◽  
Enhancer Blocking

The zinc-finger protein CTCF was originally identified in the context of gene silencing and gene repression (Baniahmad et al. 1990; Lobanenkov et al. 1990). CTCF was later shown to be involved in several transcriptional mechanisms such as gene activation (Vostrov et al. 2002) and enhancer blocking (Filippova et al. 2001; Hark et al. 2000; Kanduri et al. 2000; Lutz et al. 2003; Szabó et al. 2000; Tanimoto et al. 2003; Phillips and Corces 2009; Bell et al. 1999; Zlatanova and Caiafa 2009a, 2009b). Insulators block the action of enhancers when positioned between enhancer and promoter. CTCF was found to be required in almost all cases of enhancer blocking tested in vertebrates. This CTCF-mediated enhancer blocking is in many instances conferred by constitutive CTCF action. For some examples however, a modulation of the enhancer blocking activity was documented (Lutz et al. 2003; Weth et al. 2010). One mechanism is achieved by regulation of binding to DNA. It was shown that CTCF is not able to bind to those binding-sites containing methylated CpG sequences. At the imprinting control region (ICR) of the Igf2/H19 locus the binding-site for CTCF on the paternal allele is methylated. This prevents DNA-binding of CTCF, resulting in the loss of enhancer blocking (Bell and Felsenfeld 2000; Chao et al. 2002; Filippova et al. 2001; Hark et al. 2000; Kanduri et al. 2000, 2002; Szabó et al. 2000; Takai et al. 2001). Not only can DNA methylation interfere with CTCF binding to DNA, it was also shown in one report that RNA transcription through the CTCF binding site results in CTCF eviction (Lefevre et al. 2008). In contrast to these cases most of the DNA sites are not differentially bound by CTCF. Even CTCF interaction with its cofactor cohesin does not seem to differ in different cell types (Schmidt et al. 2010). These results indicate that regulation of CTCF activity might be achieved by neighboring factors bound to DNA. In fact, whole genome analyses of CTCF binding sites identified several classes of neighboring sequences (Dickson et al. 2010; Boyle et al. 2010; Essien et al. 2009). Therefore, in this review we will summarize those results for which a combined action of CTCF with factors bound adjacently was found. These neighboring factors include the RNA polymerases I, II and III, another zinc finger factor VEZF1 and the factors YY1, SMAD, TR and Oct4. Each of these seems to influence, modulate or determine the function of CTCF. Thereby, at least some of the pleiotropic effects of CTCF can be explained.

scholarly journals On the prediction of DNA-binding preferences of C2H2-ZF domains using structural models: application on human CTCF

2020 ◽  
Vol 2 (3) ◽  
Author(s):  
Alberto Meseguer ◽  
Filip Årman ◽  
Oriol Fornes ◽  
Ruben Molina-Fernández ◽  
Jaume Bonet ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Dna Binding ◽  
Binding Site ◽  
Zinc Finger ◽  
Zinc Finger Protein ◽  
Computational Method ◽  
Chromatin Binding ◽  
Input Structure ◽  
Binding Factor ◽  
Potential Binding

Abstract Cis2-His2 zinc finger (C2H2-ZF) proteins are the largest family of transcription factors in human and higher metazoans. To date, the DNA-binding preferences of many members of this family remain unknown. We have developed a computational method to predict their DNA-binding preferences. We have computed theoretical position weight matrices (PWMs) of proteins composed by C2H2-ZF domains, with the only requirement of an input structure. We have predicted more than two-third of a single zinc-finger domain binding site for about 70% variants of Zif268, a classical member of this family. We have successfully matched between 60 and 90% of the binding-site motif of examples of proteins composed by three C2H2-ZF domains in JASPAR, a standard database of PWMs. The tests are used as a proof of the capacity to scan a DNA fragment and find the potential binding sites of transcription-factors formed by C2H2-ZF domains. As an example, we have tested the approach to predict the DNA-binding preferences of the human chromatin binding factor CTCF. We offer a server to model the structure of a zinc-finger protein and predict its PWM.

scholarly journals Isolation of a gene encoding a functional zinc finger protein homologous to erythroid Krüppel-like factor: identification of a new multigene family.

1995 ◽  
Vol 15 (11) ◽  
pp. 5957-5965 ◽  
Author(s):  
K P Anderson ◽  
C B Kern ◽  
S C Crable ◽  
J B Lingrel
Keyword(s):  
Dna Binding ◽  
Binding Site ◽  
Zinc Finger ◽  
Reporter Gene ◽  
Zinc Finger Protein ◽  
Erythroid Cell ◽  
Specific Gene ◽  
Beta Globin ◽  
Gene Encoding ◽  
Hybridization Probe

We have identified and characterized the gene for a novel zinc finger transcription factor which we have termed lung Krüppel-like factor (LKLF). LKLF was isolated through the use of the zinc finger domain of erythroid Krüppel-like factor (ELKF) as a hybridization probe and is closely related to this erythroid cell-specific gene. LKLF is expressed in a limited number of tissues, with the predominant expression seen in the lungs and spleen. The gene is developmentally controlled, with expression noted in the 7-day embryo followed by a down-regulation at 11 days and subsequent reactivation. A high degree of similarity is noted in the zinc finger regions of LKLF and EKLF. Beyond this domain, the sequences diverge significantly, although the putative transactivation domains for both LKLF and EKLF are proline-rich regions. In the DNA-binding domain, the three zinc finger motifs are so closely conserved that the predicted DNA contact sites are identical, suggesting that both proteins may bind to the same core sequence. This was further suggested by transactivation assays in which mouse fibroblasts were transiently transfected with a human beta-globin reporter gene in the absence and presence of an LKLF cDNA construct. Expression of the LKLF gene activates this human beta-globin promoter containing the CACCC sequence previously shown to be a binding site for EKLF. Mutation of this potential binding site results in a significant reduction in the reporter gene expression. LKLF and EKLF can thus be grouped as members of a unique family of transcription factors which have discrete patterns of expression in different tissues and which appear to recognize the same DNA-binding site.

scholarly journals An exceptionally conserved transcriptional repressor, CTCF, employs different combinations of zinc fingers to bind diverged promoter sequences of avian and mammalian c-myc oncogenes.

1996 ◽  
Vol 16 (6) ◽  
pp. 2802-2813 ◽  
Author(s):  
G N Filippova ◽  
S Fagerlie ◽  
E M Klenova ◽  
C Myers ◽  
Y Dehner ◽  
...  
Keyword(s):  
Dna Binding ◽  
Binding Site ◽  
Expression Patterns ◽  
Transcriptional Repressor ◽  
Ctcf Binding ◽  
Ctcf Binding Site ◽  
Cdna Clones ◽  
Regulatory Sequences ◽  
P2 Promoter ◽  
Gel Shift

We have isolated and analyzed human CTCF cDNA clones and show here that the ubiquitously expressed 11-zinc-finger factor CTCF is an exceptionally highly conserved protein displaying 93% identity between avian and human amino acid sequences. It binds specifically to regulatory sequences in the promoter-proximal regions of chicken, mouse, and human c-myc oncogenes. CTCF contains two transcription repressor domains transferable to a heterologous DNA binding domain. One CTCF binding site, conserved in mouse and human c-myc genes, is found immediately downstream of the major P2 promoter at a sequence which maps precisely within the region of RNA polymerase II pausing and release. Gel shift assays of nuclear extracts from mouse and human cells show that CTCF is the predominant factor binding to this sequence. Mutational analysis of the P2-proximal CTCF binding site and transient-cotransfection experiments demonstrate that CTCF is a transcriptional repressor of the human c-myc gene. Although there is 100% sequence identity in the DNA binding domains of the avian and human CTCF proteins, the regulatory sequences recognized by CTCF in chicken and human c-myc promoters are clearly diverged. Mutating the contact nucleotides confirms that CTCF binding to the human c-myc P2 promoter requires a number of unique contact DNA bases that are absent in the chicken c-myc CTCF binding site. Moreover, proteolytic-protection assays indicate that several more CTCF Zn fingers are involved in contacting the human CTCF binding site than the chicken site. Gel shift assays utilizing successively deleted Zn finger domains indicate that CTCF Zn fingers 2 to 7 are involved in binding to the chicken c-myc promoter, while fingers 3 to 11 mediate CTCF binding to the human promoter. This flexibility in Zn finger usage reveals CTCF to be a unique "multivalent" transcriptional factor and provides the first feasible explanation of how certain homologous genes (i.e., c-myc) of different vertebrate species are regulated by the same factor and maintain similar expression patterns despite significant promoter sequence divergence.

scholarly journals Gfi-1 encodes a nuclear zinc finger protein that binds DNA and functions as a transcriptional repressor.

1996 ◽  
Vol 16 (8) ◽  
pp. 4024-4034 ◽  
Author(s):  
P A Zweidler-Mckay ◽  
H L Grimes ◽  
M M Flubacher ◽  
P N Tsichlis
Keyword(s):  
T Cell ◽  
Binding Site ◽  
Electrophoretic Mobility ◽  
Zinc Finger ◽  
Binding Sites ◽  
Zinc Finger Protein ◽  
Zinc Fingers ◽  
Mobility Shift ◽  
Finger Protein ◽  
Electrophoretic Mobility Shift Assays

The Gfi-1 proto-oncogene encodes a zinc finger protein with six C2H2-type, C-terminal zinc finger motifs and is activated by provirus integration in T-cell lymphoma lines selected for interleukin-2 independence in culture and in primary retrovirus-induced thymomas. Gfi-1 expression in adult animals is restricted to the thymus, spleen, and testis and is enhanced in mitogen-stimulated splenocytes. In this report, we show that Gfi-1 is a 55-kDa nuclear protein that binds DNA in a sequence-specific manner. The Gfi-1 binding site, TAAATCAC(A/T)GCA, was defined via random oligonucleotide selection utilizing a bacterially expressed glutathione S-transferase-Gfi-1 fusion protein. Binding to this site was confirmed by electrophoretic mobility shift assays and DNase I footprinting. Methylation interference analysis and electrophoretic mobility shift assays with mutant oliginucleotides defined the relative importance of specific bases at the consensus binding site. Deletion of individual zinc fingers demonstrated that only zinc fingers 3, 4, and 5 are required for sequence-specific DNA binding. Potential Gfi-1 binding sites were detected in a large number of eukaryotic promoter-enhancers, including the enhancers of several proto-oncogenes and cytokine genes and the enhancer of the human cytomegalovirus (HCMV) major immediate-early promoter, which contains two such sites. HCMV major immediate-early-chloramphenicol acetyltransferase reporter constructs, transfected into NIH 3T3 fibroblasts, were repressed by Gfi-1, and the repression was abrogated by mutation of critical residues in the two Gfi-1 binding sites. These results suggest that Gfi-1 may play a role in HCMV biology and may contribute to oncogenesis and T-cell activation by repressing the expression of genes that inhibit these processes.

scholarly journals The Myc-associated zinc finger protein (MAZ) works together with CTCF to control cohesin positioning and genome organization

2021 ◽  
Vol 118 (7) ◽  
pp. e2023127118
Author(s):  
Tiaojiang Xiao ◽  
Xin Li ◽  
Gary Felsenfeld
Keyword(s):  
Rna Polymerase Ii ◽  
Zinc Finger ◽  
Binding Sites ◽  
Genome Organization ◽  
Large Scale ◽  
Zinc Finger Protein ◽  
Ctcf Binding ◽  
Finger Protein ◽  
Topologically Associated Domains ◽  
Cohesin Subunit

The Myc-associated zinc finger protein (MAZ) is often found at genomic binding sites adjacent to CTCF, a protein which affects large-scale genome organization through its interaction with cohesin. We show here that, like CTCF, MAZ physically interacts with a cohesin subunit and can arrest cohesin sliding independently of CTCF. It also shares with CTCF the ability to independently pause the elongating form of RNA polymerase II, and consequently affects RNA alternative splicing. CTCF/MAZ double sites are more effective at sequestering cohesin than sites occupied only by CTCF. Furthermore, depletion of CTCF results in preferential loss of CTCF from sites not occupied by MAZ. In an assay for insulation activity like that used for CTCF, binding of MAZ to sites between an enhancer and promoter results in down-regulation of reporter gene expression, supporting a role for MAZ as an insulator protein. Hi-C analysis of the effect of MAZ depletion on genome organization shows that local interactions within topologically associated domains (TADs) are disrupted, as well as contacts that establish the boundaries of individual TADs. We conclude that MAZ augments the action of CTCF in organizing the genome, but also shares properties with CTCF that allow it to act independently.

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