Regulatory Precision in Stress Responsive Transcriptional Networks

PROJECT SUMMARY Many cellular challenges ? chemical, metabolic, and physical ? generate reactive oxygen species (ROS), which have the potential to damage macromolecules including proteins, lipids, and nucleic acids. Members of the Cap-n-Collar (CNC) transcription factor family, including NRF2, regulate antioxidant gene expression and mitigate ROS-mediated damage. These opposing oxidant and antioxidant forces must be precisely balanced: too little NRF2 and excess ROS cause cell damage and mutation, whereas too much NRF2 gives cells a dangerous proliferative advantage. To fully understand the mechanistic implications of NRF2 activation we need a comprehensive view of its regulatory network, yet surprisingly little is known about the global reach of NRF2's regulatory activity and how it integrates with additional stress-responsive transcription factors. We will use a combination of hypothesis-driven genomics and focused biological validation experiments to provide both systems level and mechanistic insights into the NRF2 regulatory network and consequences of its activation. Importantly, this work will also address issues regarding the general principles of transcriptional regulatory precision, including: (1) how transcription factor DNA binding properties and combinatorial transcription factor interactions integrate to drive graded versus switch-like gene expression, (2) the dynamics and cell-type specificity of rapid transcriptional reprogramming in human cells, (3) how variation in cis- regulatory DNA is functionally linked to disease risk, and (4) the mechanisms of cell autonomous and non- autonomous regulatory network propagation. These are relevant issues for all transcriptional regulators, so the knowledge gained in the context of NRF2-mediated gene regulation will also extend to additional transcription factor families.