Dynamics of transcriptional regulatory complexes: Mechanism and function

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This project will define a new mechanism for dynamic regulation of gene expression. Turning a gene on or off is known to occur by assembly of a "regulatory protein machine" on the DNA near the gene. Such machines are composed of gene-specific combinations of proteins that work as a unit to switch the gene on or off in particular cells in particular ways. Emerging results indicate that mechanisms have evolved to actively disassemble these machines, resulting in a dynamic process of machine building and breakdown. This project will investigate how the dynamics of these regulatory protein machines alters the expression patterns of specific genes. The study is important because gene expression patterns have long been thought to be specified solely by the makeup of the regulatory machines without considering the role played by dynamics of machine building and breakdown. The results of this work will define factors involved in regulatory machinery dynamics and how they selectively modulate gene expression patterns. Notably, this research plan is integral to the career planning, development, and advancement to independence of an outstanding woman scientist, providing valuable experience in conceiving, executing and managing an original, impactful research program.Focusing on the glucocorticoid receptor (GR), this project will test the hypothesis that transcriptional regulatory complex (TRC) dynamics is a determinant of specific gene expression. The steroid hormone cortisol, which gates GR activity, circulates at levels that fluctuate according to circadian and ultradian (~1 hour) cycles, and spike in response to certain external cues. DNA-bound GR-containing TRCs are highly dynamic in vivo, with disassembly driven by molecular chaperones. This project will 1) define mechanisms of GR:DNA dynamics; 2) identify factors that target chaperones to TRCs to confer disassembly; and 3) determine effects of TRC dynamics on GR-regulated transcription. Mechanisms will be pursued in vitro and in cultured cells using molecular biological, biochemical, and proteomic methods to define how chaperone-mediated dynamics confers specific transcription patterns in response to glucocorticoid fluctuations. Revealing dynamics as a regulatory modality will advance understanding of context-specific metazoan gene expression, the principle mechanism that distinguishes cells types and shapes biological processes.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.