DNA break induces rapid transcription repression mediated by proteasome-dependent RNAPII removal

A DNA double-strand break (DSB) jeopardizes genome integrity and endangers cell viability. Actively transcribed genes are particularly detrimental if broken and need to be repressed. However, it remains elusive how fast the repression is initiated and how far it influences the neighboring genes on the chromosome. We adopt a recently developed, very fast CRISPR to generate a DSB at a specific genomic locus with precise timing, visualize transcription in live cells, and measure the RNA polymerase II (RNAPII) occupancy near the broken site. We observe that a single DSB represses the transcription of the damaged gene in minutes, which coincides with the recruitment of a damage repair protein. Transcription repression propagates bi-directionally along the chromosome from the DSB for hundreds of kilobases, and proteasome is evoked to remove RNAPII in this process. Our method builds a foundation to measure the rapid kinetic events around a single DSB and elucidate the molecular mechanism. [Display omitted] •Single double-strand break causes transcription repression of broken genes in a few minutes•Transcription repression propagates along the chromosome for hundreds of kilobases•Rapid transcription repression is not regulated by PRC1-mediated H2A K119 ubiquitination•Proteasome-mediated RNAPII removal contributes to transcription repression and propagation He et al. apply light-activated CRISPR to induce a DNA double-strand break and observe rapid transcription repression and its propagation along the damaged chromosome. They demonstrate that proteasomes remove RNAPII around the damaged site. Their method builds a foundation to measure the kinetics after DSB and elucidate the molecular mechanism.