A negatively-charged region within C-terminal domain maintains proper CTCF DNA binding (RNA-Seq)
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE261212 | GEO | 2024/11/30
REPOSITORIES: GEO
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Project description:As an essential regulator of higher-order chromatin structures, CTCF is a highly conserved DNA binding protein with a central DNA-binding domain of 11 tandem zinc fingers, which are flanked by N- and C-terminal domains of intrinsically disordered regions. The N-terminal domain interacts with cohesin complex and the central ZF domains recognize a large range of diverse genomic sites. However, the function of C-terminal unstructured domain remains less understood. Here, we found that deletion of C-terminal fragment of 116 amino acid increases CTCF-DNA binding. By genetic dissection of this fragment, we uncovered a negatively-charged region responsible for repressing CTCF binding to DNA. Thus, the unstructured C-terminal domain play an important role in maintaining proper CTCF-DNA interactions.
2024-11-30 | GSE261213 | GEO
Project description:As an essential regulator of higher-order chromatin structures, CTCF is a highly conserved DNA binding protein with a central DNA-binding domain of 11 tandem zinc fingers, which are flanked by N- and C-terminal domains of intrinsically disordered regions. The N-terminal domain interacts with cohesin complex and the central ZF domains recognize a large range of diverse genomic sites. However, the function of C-terminal unstructured domain remains less understood. Here, we found that deletion of C-terminal fragment of 116 amino acid increases CTCF-DNA binding. By genetic dissection of this fragment, we uncovered a negatively-charged region responsible for repressing CTCF binding to DNA. Thus, the unstructured C-terminal domain play an important role in maintaining proper CTCF-DNA interactions.
2024-11-30 | GSE261210 | GEO
Project description:As an essential regulator of higher-order chromatin structures, CTCF is a highly conserved DNA binding protein with a central DNA-binding domain of 11 tandem zinc fingers, which are flanked by N- and C-terminal domains of intrinsically disordered regions. The N-terminal domain interacts with cohesin complex and the central ZF domains recognize a large range of diverse genomic sites. However, the function of C-terminal unstructured domain remains less understood. Here, we found that deletion of C-terminal fragment of 116 amino acid increases CTCF-DNA binding. By genetic dissection of this fragment, we uncovered a negatively-charged region responsible for repressing CTCF binding to DNA. Thus, the unstructured C-terminal domain play an important role in maintaining proper CTCF-DNA interactions.
2024-11-30 | GSE261209 | GEO
Project description:CTCF is the main architectural protein found in the majority of examined bilaterians. CTCFs of various organisms contain unstructured N-terminal dimerization domain (DD) along with clusters consisting of eleven zinc-finger domains of C2H2 type. The Drosophila (dCTCF) and human (hCTCF) CTCF share sequence homology only in five C2H2 domains that specifically bind to conserved 15 bp motif. By using CTCFattP(mCh) platform to introduce desired changes in the Drosophila CTCF gene, we generated a series of transgenic lines expressing dCTCF with different variants of the N-terminal domain. Our findings revealed that the functionality of dCTCF is significantly affected solely by the deletion of the N-terminal DD. Also, we observed a strong impact on the binding of the dCTCF mutant to chromatin upon deletion of the DD. However, chromatin binding was restored in transgenic flies expressing a chimeric CTCF protein with the DD of hCTCF. Although the chimeric protein exhibited lower expression level compared to the dCTCF variants, it efficiently bound to chromatin similar to the wild type (wt) protein. Our results suggest that one of the evolutionarily conserved function of the unstructured dimerization domain is to recruit dCTCF to its binding sites in vivo.
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Project description:Insulators are DNA elements, which prevent inappropriate interactions between the neighboring regions of the genome. They can be functionally classified as either enhancer blockers or domain barriers. CTCF (CCCTC binding factor) is the only known major insulator binding protein in the vertebrates and has been shown to bind many enhancer-blocking elements. However, it is not clear whether it plays a role in chromatin domain barriers between active and repressive domains. Here, we used ChIP-Seq to map the genome-wide binding sites of CTCF in three cell types and identified significant binding of CTCF to the boundaries of repressive chromatin domains marked by H3K27me3. Although we find an extensive overlapping of CTCF binding sites across the three cell types, its association with the domain boundaries is cell type-specific. We further show that the nucleosomes flanking CTCF binding sites are well positioned and associated with histone H2AK5 acetylation (H2AK5ac). Interestingly, we found a complementary pattern between the repressive H3K27me3 and the active H2AK5ac regions, which are separated by CTCF. Our findings indicate that CTCF may play important roles in the barrier activity of insulators and provide a resource for further investigation of the CTCF function in organizing chromatin in the human genome. Examination of the role of CTCF in chromatin domain barrier function In addition to the ChIP-seq analysis, two replicates of HeLa expression data were studied.
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Project description:The Drosophila male-specific lethal (MSL) complex binds to the male X chromosome to activate transcription, and consists of five proteins, MSL1, MSL2, MSL3, MOF, MLE, and two roX RNAs. The MLE helicase remodels the roX lncRNAs, enabling the lncRNA-mediated assembly of the Drosophila dosage compensation complex. MSL2 is expressed only in males and interacts with the N-terminal zinc-finger of the transcription factor CLAMP that is important for specific recruitment of the MSL complex on the male X chromosome. Here we found that the unstructured C-terminal region of MLE interacts with 6-7 zinc-finger domains of CLAMP. In vitro 4-5 zinc fingers are critical for specific DNA-binding of CLAMP with GA-repeats, which constitute the core motif at the high affinity binding sites for MSL proteins. Deletion of the Clamp Binding Domain (CBD) in MLE results in decreasing of MSL proteins association with male X chromosome and increasing of male lethality. These results suggest that interactions of unstructured regions in MSL2 and MLE with CLAMP zinc finger domains are important for the specific recruitment of the MSL complex on the male X chromosome.
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Project description:Histone modifications associated with gene silencing typically mark large contiguous regions of the genome forming repressive chromatin domain structures. Since the repressive domains exist in close proximity to active regions, maintenance of domain structure is critically important. This study shows that nickel, a nonmutagenic carcinogen, can disrupt histone H3 lysine 9 dimethylation (H3K9me2) domain structures genome-wide, resulting in spreading of H3K9me2 marks into the active regions, which is associated with gene silencing. Our results suggest inhibition of DNA binding of the insulator protein CCCTC-binding factor (CTCF) at the H3K9me2 domain boundaries as a potential reason for H3K9me2 domain disruption. These findings have major implications in understanding chromatin dynamics and the consequences of chromatin domain disruption during pathogenesis. Investigations into the genomic landscape of histone modifications in heterochromatic regions have revealed histone H3 lysine 9 dimethylation (H3K9me2) to be important for differentiation and maintaining cell identity. H3K9me2 is associated with gene silencing and is organized into large repressive domains that exist in close proximity to active genes, indicating the importance of maintenance of proper domain structure. Here we show that nickel, a nonmutagenic environmental carcinogen, disrupted H3K9me2 domains, resulting in the spreading of H3K9me2 into active regions, which was associated with gene silencing. We found weak CCCTC-binding factor (CTCF)-binding sites and reduced CTCF binding at the Ni-disrupted H3K9me2 domain boundaries, suggesting a loss of CTCF-mediated insulation function as a potential reason for domain disruption and spreading. We furthermore show that euchromatin islands, local regions of active chromatin within large H3K9me2 domains, can protect genes from H3K9me2-spreadingM-bM-^@M-^Sassociated gene silencing. These results have major implications in understanding H3K9me2 dynamics and the consequences of chromatin domain disruption during pathogenesis.
2014-09-24 | E-GEOD-56053 | biostudies-arrayexpress
Project description:Transcription factors are often regarded as being comprised of a DNA-binding domain and a functional domain. The two domains are considered separable and autonomous, with the DNA-binding domain directing the factor to its target genes and the functional domain imparting transcriptional regulation. We have examined a typical Zinc Finger (ZF) transcription factor from the Krüppel-like factor (KLF) family, KLF3. This factor has an N-terminal repression domain that binds the co-repressor C-terminal binding protein (CtBP), and a DNA-binding domain composed of three classical (ZFs) at its C-terminus. We established a system to compare the genomic occupancy profile of wildtype KLF3 with two mutants affecting the N-terminal functional domain: a mutant unable to contact its cofactor CtBP and a mutant lacking the entire N-terminal domain, but retaining the ZFs intact. We used chromatin immunoprecipitation followed by sequencing (ChIP-seq) to assess binding across the genome in murine embryonic fibroblasts. Our results define the in vivo recognition site for KLF3 and the two mutants as a typical CACCC-like element. Unexpectedly, we observe that mutations in the N-terminal functional domain severely affect DNA binding. In general, both mutations reduce binding but there are also instances where binding is retained or even increased. These results provide a clear demonstration that the correct localization of transcription factors to their target genes is not solely dependent on their DNA-contact domains. This informs our understanding of how transcription factors operate and is of relevance to the design of artificial ZF proteins. ChIP-seq was performed on the three samples, KLF3, ΔDL and DBD in duplicate (biological replicates). Input samples were used as controls.
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Project description:Histone post-translational modifications play pivotal roles in eukaryotic gene expression. To date, most studies have focused on modifications in unstructured histone N-terminal tail domains and their binding proteins. However, transcriptional regulation by chromatin-effector proteins that directly recognize modifications in histone globular domains has yet to be clearly demonstrated, despite the richness of their multiple modifications. Here, we show that the ATP-dependent chromatin-remodeling BAF complex stimulates p53-dependent transcription through direct interaction with H3K56ac located on the lateral surface of the histone globular domain. Mechanistically, the BAF complex recognizes nucleosomal H3K56ac via the DPF domain in the DPF2 subunit and exhibits enhanced nucleosome-remodeling activity in the presence of H3K56ac. We further demonstrate that a defect in H3K56ac–BAF complex interaction leads to impaired p53-dependent gene expression and DNA damage responses. Our study provides direct evidence that histone globular domain modifications participate in the regulation of gene expression.
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Project description:Histone post-translational modifications play pivotal roles in eukaryotic gene expression. To date, most studies have focused on modifications in unstructured histone N-terminal tail domains and their binding proteins. However, transcriptional regulation by chromatin-effector proteins that directly recognize modifications in histone globular domains has yet to be clearly demonstrated, despite the richness of their multiple modifications. Here, we show that the ATP-dependent chromatin-remodeling BAF complex stimulates p53-dependent transcription through direct interaction with H3K56ac located on the lateral surface of the histone globular domain. Mechanistically, the BAF complex recognizes nucleosomal H3K56ac via the DPF domain in the DPF2 subunit and exhibits enhanced nucleosome-remodeling activity in the presence of H3K56ac. We further demonstrate that a defect in H3K56ac–BAF complex interaction leads to impaired p53-dependent gene expression and DNA damage responses. Our study provides direct evidence that histone globular domain modifications participate in the regulation of gene expression.
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