Our new preprint from @arjunrajlab @blobelgroup! Transcriptional burst initiation and polymerase pause release are key control points of transcriptional regulation. (Thread) biorxiv.org/content/early/…
2.We asked which steps of transcription are regulated by biological perturbations? (we used a mouse red blood cell line for all experiments)
3.Take home conclusion: frequency of transcriptional bursting and transcriptional pause release rate are the two main regulated rates of transcription. 
4.BET protein inhibition and erythroid differentiation changed both transcriptional burst frequency and polymerase pause release rate
5.The rates of polymerase binding and of transcriptional burst termination were mostly NOT changed
6.Our approach: comparing experimental results from single-cell RNA FISH and Pol II ChIP-seq to predictions of quantitative models
7.If burst frequency is a key regulated rate of transcription, what happens molecularly when a burst starts?? (unlike polymerase pause release, the field doesn’t know a lot about the mechanism of bursting)
8.We found that forced enhancer-promoter looping, as well as acutely increased GATA-1 transcription factor levels, specifically increased burst frequency (without changing other transcriptional rates)
9.This work provides a framework to identify changes in transcriptional rates: pick a drug (or other stimulus), do Pol II ChIP-seq and RNA FISH on some genes, and I can tell you which step(s) of transcription are altered!
10.Future directions: to use RNA FISH amplification technology developed in the lab by @SRouhanifard to take a population of cells, and sort bursting from non-transcribing cells, and perform chip/3C to see what’s going on during a burst
11.Questions and comments welcome! We're really excited to discuss this work!
also huge thanks to @KellerCaponePhD @rosshardison for their work!
