CHROMATIN INTERACTION MECHANISM OF TRANSCRIPTIONAL CONTROL IN-VIVO

We have used a kinetic analysis to distinguish possible mechanisms of activation of transcription of the different genes in the human beta g lobin locus. Based on in situ studies at the single-cell level we have previously suggested a dynamic mechanism of single genes alternately interacting with the locus control region (LCR) to activate transcript ion. However, those steady-state experiments did not allow a direct me asurement of the dynamics of the mechanism and the presence of loci wi th in situ primary transcript signals from two beta-like genes in cis has left open the possibility that multiple genes in the locus could i nitiate transcription simultaneously. Kinetic assays involving removal of a block to transcription elongation in conjunction with RNA FISH s how that multiple beta gene primary transcript signals in cis represen t a transition between alternating transcriptional periods of single g enes, supporting a dynamic interaction mechanism.