@article {Rademacher132050, author = {Anne Rademacher and Fabian Erdel and Jorge Trojanowski and Karsten Rippe}, title = {Real-time observation of light-controlled transcription in living cells}, elocation-id = {132050}, year = {2017}, doi = {10.1101/132050}, publisher = {Cold Spring Harbor Laboratory}, abstract = {Gene expression is a tightly controlled process that is coordinated in space and time. To dissect its dynamic regulation with high temporal resolution, we introduce an optogenetic tool termed BLInCR (Blue Light-Induced Chromatin Recruitment) that combines rapid and reversible light-dependent recruitment of effector proteins with a real-time readout for transcription. We used BLInCR to control the activity of a reporter gene cluster in the human osteosarcoma cell line U2OS by reversibly recruiting the viral transactivator VP16. RNA production was detectable \~{}2 minutes after VP16 recruitment and readily decreased when VP16 dissociated from the cluster in the absence of light. Quantitative assessment of the activation process revealed biphasic activation kinetics with a pronounced early phase in cells treated with the histone deacetylase inhibitor SAHA. Comparison with kinetic models for transcription activation suggests that the gene cluster undergoes a maturation process when activated. BLInCR will facilitate the study of transcription dynamics in living cells.}, URL = {https://www.biorxiv.org/content/early/2017/04/28/132050}, eprint = {https://www.biorxiv.org/content/early/2017/04/28/132050.full.pdf}, journal = {bioRxiv} }