scholarly journals Intragenic CpG islands play important roles in bivalent chromatin assembly of developmental genes

2017 ◽  
Vol 114 (10) ◽  
pp. E1885-E1894 ◽  
Author(s):  
Sun-Min Lee ◽  
Jungwoo Lee ◽  
Kyung-Min Noh ◽  
Won-Young Choi ◽  
Sejin Jeon ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Transcriptional Activation ◽  
Epigenetic Modification ◽  
Embryonic Stem ◽  
Housekeeping Genes ◽  
Regulation Of Transcription ◽  
Physical Interaction ◽  
Cell Type ◽  
Cell Type Specific ◽  
Specific Regulation

CpG, 5′-C-phosphate-G-3′, islands (CGIs) have long been known for their association with enhancers, silencers, and promoters, and for their epigenetic signatures. They are maintained in embryonic stem cells (ESCs) in a poised but inactive state via the formation of bivalent chromatin containing both active and repressive marks. CGIs also occur within coding sequences, where their functional role has remained obscure. Intragenic CGIs (iCGIs) are largely absent from housekeeping genes, but they are found in all genes associated with organ development and cell lineage control. In this paper, we investigated the epigenetic status of iCGIs and found that they too reside in bivalent chromatin in ESCs. Cell type-specific DNA methylation of iCGIs in differentiated cells was linked to the loss of both the H3K4me3 and H3K27me3 marks, and disruption of physical interaction with promoter regions, resulting in transcriptional activation of key regulators of differentiation such as PAXs, HOXs, and WNTs. The differential epigenetic modification of iCGIs appears to be mediated by cell type-specific transcription factors distinct from those bound by promoter, and these transcription factors may be involved in the hypermethylation of iCGIs upon cell differentiation. iCGIs thus play a key role in the cell type-specific regulation of transcription.

Epigenetic Regulation of the Dendritic Cell Marker Gene MADDAM /ADAM19.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 4187-4187
Author(s):  
Marina Kreutz ◽  
Achim Ehrnsperger ◽  
Michael Rehli ◽  
Reinhard Andreesen
Keyword(s):  
Transcription Factors ◽  
Dendritic Cell ◽  
Binding Sites ◽  
Cpg Island ◽  
Trichostatin A ◽  
Proximal Promoter ◽  
Cell Type ◽  
Reporter Activity ◽  
Cell Type Specific ◽  
Specific Regulation

Abstract MADDAM (Metalloprotease And Disintegrin Dendritic Cell Antigen Marker, ADAM19), a human metalloprotease belonging to the ADAM-family, is strongly expressed during in vitro differentiation of monocytes into dendritic cells (DC), whereas differentiation of monocytes into macrophages (MAC) is associated with a loss of MADDAM transcription. To investigate the mechanisms underlying this cell-type specific expression pattern we defined the transcriptional start site and the proximal promoter of the MADDAM gene. Gene bank analysis of the CpG island promoter and first intron revealed putative binding sites for several transcription factors, including VDR, NF-kB and Sp1-family factors. EMSA demonstrated binding of Sp1, Sp3, NF-kB and VDR to their putative binding sites in the proximal promoter region and mutation of these elements led to a decreased reporter activity of the proximal promoter in luciferase assays. A minimal promoter construct of 150-bp showed weak reporter activity in primary monocyte-derived MAC and a threefold higher activity in monocyte-derived DC, indicating that differential binding of transcription factors contributes to the cell-type specific regulation of MADDAM. Transfection of monocytic THP-1 cells with the 150-bp fragment also resulted in significant reporter activity, despite the lack of endogenous MADDAM expression. Interestingly, Trichostatin A (TSA), a known inhibitor of histone deacetylation, lead to a dose dependent induction of MADDAM mRNA in THP-1 cells. Chromatin immunoprecipitation (ChIP) assays demonstrate increased levels of acetylated histones H3 and H4 in DC as compared to MAC, indicating an important role of histone acetylation in the cell-type specific regulation of the MADDAM gene.

scholarly journals Developmentally Programmed 3′ CpG Island Methylation Confers Tissue- and Cell-Type-Specific Transcriptional Activation

2013 ◽  
Vol 33 (9) ◽  
pp. 1845-1858 ◽  
Author(s):  
Da-Hai Yu ◽  
Carol Ware ◽  
Robert A. Waterland ◽  
Jiexin Zhang ◽  
Miao-Hsueh Chen ◽  
...  
Keyword(s):  
Transcriptional Regulation ◽  
Transcriptional Activation ◽  
Functional Role ◽  
Cpg Island ◽  
Embryonic Stem ◽  
Luciferase Reporter ◽  
Specific Gene ◽  
Cell Type ◽  
Cell Type Specific

During development, a small but significant number of CpG islands (CGIs) become methylated. The timing of developmentally programmed CGI methylation and associated mechanisms of transcriptional regulation during cellular differentiation, however, remain poorly characterized. Here, we used genome-wide DNA methylation microarrays to identify epigenetic changes during human embryonic stem cell (hESC) differentiation. We discovered a group of CGIs associated with developmental genes that gain methylation after hESCs differentiate. Conversely, erasure of methylation was observed at the identified CGIs during subsequent reprogramming to induced pluripotent stem cells (iPSCs), further supporting a functional role for the CGI methylation. Both global gene expression profiling and quantitative reverse transcription-PCR (RT-PCR) validation indicated opposing effects of CGI methylation in transcriptional regulation during differentiation, with promoter CGI methylation repressing and 3′ CGI methylation activating transcription. By studying diverse human tissues and mouse models, we further confirmed that developmentally programmed 3′ CGI methylation confers tissue- and cell-type-specific gene activationin vivo. Importantly, luciferase reporter assays provided evidence that 3′ CGI methylation regulates transcriptional activation via a CTCF-dependent enhancer-blocking mechanism. These findings expand the classic view of mammalian CGI methylation as a mechanism for transcriptional silencing and indicate a functional role for 3′ CGI methylation in developmental gene regulation.

scholarly journals A common intermediary factor (p52/54) recognizing "acidic blob"-type domains is required for transcriptional activation by the Jun proteins.

1992 ◽  
Vol 12 (12) ◽  
pp. 5508-5515 ◽  
Author(s):  
T Oehler ◽  
P Angel
Keyword(s):  
Transcription Factors ◽  
Rna Polymerase Ii ◽  
Transcriptional Activation ◽  
Target Genes ◽  
Serum Response Factor ◽  
Limiting Factor ◽  
Regulation Of Transcription ◽  
Physical Interaction ◽  
Main Component

The ability of the c-Jun protein, the main component of the transcription factor AP1, to interact directly or indirectly with the RNA polymerase II-initiation complex to activate transcription was investigated by in vivo transcription interference ("squelching") experiments. Coexpression of a Jun mutant lacking its DNA binding domain strongly represses the activity of wild-type c-Jun. Repression depends on the presence of the transactivation domains (TADs), suggesting that a limiting factor interacting with the TADs is essential to link Jun and the components of the transcriptional machinery. The activity of this intermediary factor(s) is restricted to TADs characterized by an abundance of negatively charged amino acids, as demonstrated by the abilities of the TADs of JunB, GAL4, and VP16 to repress c-Jun activity. Depending on the presence of the TADs of Jun, we found physical interaction between Jun and a cluster of three proteins with molecular masses of 52, 53, and 54 kDa (p52/54). Association between Jun and p52/54 is strongly reduced in the presence of VP16, suggesting that the two proteins compete for binding to p52/54. Transcription factors containing a different type of TAD (e.g., GHF1, estrogen receptor, or serum response factor) fail to inhibit Jun activity, suggesting that these proteins act through a different mechanism. We consider the requirement of Jun to interact with p52/54 utilized by other transcription factors a new mechanism in the regulation of transcription of Jun-dependent target genes.

A common intermediary factor (p52/54) recognizing "acidic blob"-type domains is required for transcriptional activation by the Jun proteins

1992 ◽  
Vol 12 (12) ◽  
pp. 5508-5515
Author(s):  
T Oehler ◽  
P Angel
Keyword(s):  
Transcription Factors ◽  
Rna Polymerase Ii ◽  
Transcriptional Activation ◽  
Target Genes ◽  
Serum Response Factor ◽  
Limiting Factor ◽  
Regulation Of Transcription ◽  
Physical Interaction ◽  
Main Component

The ability of the c-Jun protein, the main component of the transcription factor AP1, to interact directly or indirectly with the RNA polymerase II-initiation complex to activate transcription was investigated by in vivo transcription interference ("squelching") experiments. Coexpression of a Jun mutant lacking its DNA binding domain strongly represses the activity of wild-type c-Jun. Repression depends on the presence of the transactivation domains (TADs), suggesting that a limiting factor interacting with the TADs is essential to link Jun and the components of the transcriptional machinery. The activity of this intermediary factor(s) is restricted to TADs characterized by an abundance of negatively charged amino acids, as demonstrated by the abilities of the TADs of JunB, GAL4, and VP16 to repress c-Jun activity. Depending on the presence of the TADs of Jun, we found physical interaction between Jun and a cluster of three proteins with molecular masses of 52, 53, and 54 kDa (p52/54). Association between Jun and p52/54 is strongly reduced in the presence of VP16, suggesting that the two proteins compete for binding to p52/54. Transcription factors containing a different type of TAD (e.g., GHF1, estrogen receptor, or serum response factor) fail to inhibit Jun activity, suggesting that these proteins act through a different mechanism. We consider the requirement of Jun to interact with p52/54 utilized by other transcription factors a new mechanism in the regulation of transcription of Jun-dependent target genes.

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