RT Journal
A1 Hartl, Dominik
A1 Krebs, Arnaud R.
A1 Grand, Ralph S.
A1 Baubec, Tuncay
A1 Isbel, Luke
A1 Wirbelauer, Christiane
A1 Burger, Lukas
A1 Schübeler, Dirk
T1 CG dinucleotides enhance promoter activity independent of DNA methylation
JF Genome Research 
JO Genome Research 
YR 2019 
FD April 01 
VO 29 
IS 4 
SP 554 
OP 563 
DO 10.1101/gr.241653.118 
UL http://genome.cshlp.org/content/29/4/554.abstract 
AB Most mammalian RNA polymerase II initiation events occur at CpG islands, which are rich in CpGs and devoid of DNA methylation. Despite their relevance for gene regulation, it is unknown to what extent the CpG dinucleotide itself actually contributes to promoter activity. To address this question, we determined the transcriptional activity of a large number of chromosomally integrated promoter constructs and monitored binding of transcription factors assumed to play a role in CpG island activity. This revealed that CpG density significantly improves motif-based prediction of transcription factor binding. Our experiments also show that high CpG density alone is insufficient for transcriptional activity, yet results in increased transcriptional output when combined with particular transcription factor motifs. However, this CpG contribution to promoter activity is independent of DNA methyltransferase activity. Together, this refines our understanding of mammalian promoter regulation as it shows that high CpG density within CpG islands directly contributes to an environment permissive for full transcriptional activity.