Fine-tuning transcriptional activity of transcriptional regulatory factors by DNA-sequence induced selective use of coregulators

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The goal of this project is to understand how transcriptional outputs are modulated by context-specific cooperations between transcription factors (TFs) and coregulators. DNA guides TFs to defined genomic loci to regulate the expression of genes. The ability of TFs to activate transcription critically depends on the recruitment of coregulators for example in order to assemble the pre initiation complex to initiate transcription. The role of DNA binding sites was traditionally thought to be restricted to simply recruiting TFs. Recent studies however revealed that DNA sequences induce alternative conformations in the associated TF resulting in different regulatory activities. In work preceding this proposal we have identified DNA binding site sequence-specific coregulators of the glucocorticoid receptor (GR), a hormone dependent TF. Specifically, we identified coactivators Brm and BATF3 and a corepressor HDAC10. Here we will employ in vitro approaches to study how the sequence of DNA binding sites influences the ability of GR to interact with these and other coregulators. In parallel, we will determine their role in the regulation of endogenous GR-target genes using microarrays and determine the genomic loci to which these coregulators are recruited by GR using chromatin immunoprecipitation experiments. Together, these studies will provide novel insights into how TFs and coregulators cooperate in a context-dependent manner to fine-tune the expression levels of individual target genes.