RACK7 Senses and Fine-Tunes Enhancer Activity [ChIP-Seq]

Enhancers regulate dynamic gene expression in a spatiotemporal specific manner. A number of positive as well as negative regulators of enhancers have been reported so far. However, whether and how these regulators sense enhancer activity dynamics remains unclear. In this study, we show that a specific enhancer regulator, RACK7, swiftly re-distributes from repressed enhancers to activated enhancers in response to a plethora of acute stimulations. We further show that this process depends on transcription and RACK7 positively regulates enhancer activation by promoting the recruitment of RNA polymerase II. Taken together, our findings suggest that RACK7 senses enhancer activity changes and facilitates their activation during acute stimulations. Overall design: HeLa and MCF-7 cells are maintained in Dulbecco's Modified Eagle's Medium supplemented with 10% fetal bovine serum, 1% Non-Essential Amino Acids, 1% Penicillin-Streptomycin Solution. When preparing for E2 stimulation in MCF-7 cells, the cells are transferred to a Phenol Red-free RPMI-1640 Medium supplemented with 10% Charcoal Stripped Fetal Bovine Serum, 1% Non-Essential Amino Acids, 1% Penicillin-Streptomycin Solution, 1% Glutamine for three days prior to 17ß-estradiol (E2) treatment. The culture medium is replaced on the second day, and a 1-hour treatment with 100 nM E2 or equal volume of EtOH was administered prior to cell harvest. For PBS or epidermal growth factor (EGF) treatment in HeLa cells, the cells are transferred to a medium containing 0.5% fetal bovine serum, refresh the culture medium on the second day. Following a 48h of serum starvation, the starved cells are then subjected to a 20-minute treatment with 50 ng/mL of EGF.