The Stat3/GR interaction code: predictive value of direct/indirect DNA recruitment for transcription outcome. Mus musculus

Transcription factor recruitment to genomic sites of action is primarily due to direct protein:DNA interactions. The subsequent recruitment of co-regulatory complexes leads to either transcriptional activation or repression. In contrast to this canonical scheme, some transcription factors such as the glucocorticoid receptor (GR) behave as transcriptional repressors when recruited to target genes through protein tethering. We have investigated the genome-wide prevalence of tethering between GR and Stat3 and found non-reciprocal interactions, namely that GR tethering to DNA-bound Stat3 results in transcriptional repression whereas Stat3 tethering to GR results in synergism. Further, other schemes of GR and Stat3 co-recruitment to regulatory modules result in transcriptional synergism, including neighbouring and composite binding sites. The results indicate extensive transcriptional interactions between Stat3 and GR; further, they provide a genome-wide assessment of transcriptional regulation by tethering and a molecular basis for integration of signals mediated by GR and Stats in health and disease. Overall design: ChIP-seq analysis of Stat3 and GR binding sites in pituitary corticotroph AtT-20 cell model. Five independant ChIPs were pooled prior library preparation for each contitions: STAT3 (LIF), STAT3 (Dex+LIF), GR (Dex+LIF), GR (Dex) and control IgG.