Mechanical force derived from transcriptional activity can induce local order and frozen motion in interphase chromosome

Recent experiments reported that dynamics of human interphase chromosome is accelerated by inhibiting transcription. This result is counterintuitive as transcription involves the elongation process of RNA polymerase which is known to exert force along DNA. To understand this phenomenon, we investigated, using polymer simulations, how mechanical force derived from transcriptional activity affects the dynamic properties of interphase chromosome. In our simulations, a pair of active forces is exerted on chromosome loci in an extensile manner to mimic the effect of transcriptional elongation. We observe that the dynamics of the active polymer chain becomes slower than that of a passive one, which is already in a glassy regime. We demonstrate that the active force gives rise to local crystallization along with frozen motion in a particular range of the force magnitude. By noting the extent of agreement between our results and experimental observations, we suggest the possibility of local order in interphase chromosome induced by transcriptional activity and its contribution to chromatin structure and dynamics.