RT Journal Article SR Electronic T1 S-phase transcriptional buffering quantified on two different promoters JF Life Science Alliance JO Life Sci. Alliance FD Life Science Alliance LLC SP e201800086 DO 10.26508/lsa.201800086 VO 1 IS 5 A1 Sharon Yunger A1 Pinhas Kafri A1 Liat Rosenfeld A1 Eliraz Greenberg A1 Noa Kinor A1 Yuval Garini A1 Yaron Shav-Tal YR 2018 UL https://www.life-science-alliance.org/content/1/5/e201800086.abstract AB Imaging of transcription by quantitative fluorescence-based techniques allows the examination of gene expression kinetics in single cells. Using a cell system for the in vivo visualization of mammalian mRNA transcriptional kinetics at single-gene resolution during the cell cycle, we previously demonstrated a reduction in transcription levels after replication. This phenomenon has been described as a homeostasis mechanism that buffers mRNA transcription levels with respect to the cell cycle stage and the number of transcribing alleles. Here, we examined how transcriptional buffering enforced during S phase affects two different promoters, the cytomegalovirus promoter versus the cyclin D1 promoter, that drive the same gene body. We found that global modulation of histone modifications could completely revert the transcription down-regulation imposed during replication. Furthermore, measuring these levels of transcriptional activity in fixed and living cells showed that the transcriptional potential of the genes was significantly higher than actual transcription levels, suggesting that promoters might normally be limited from reaching their full transcriptional potential.