TY - JOUR T1 - Real-time observation of light-controlled transcription in living cells JF - bioRxiv DO - 10.1101/132050 SP - 132050 AU - Anne Rademacher AU - Fabian Erdel AU - Jorge Trojanowski AU - Karsten Rippe Y1 - 2017/01/01 UR - http://biorxiv.org/content/early/2017/04/28/132050.abstract N2 - 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. ER -