Orphan nuclear receptor TR4 uses non-equivalent binding sites to regulate gene targets from proximal and distal transcriptional regulatory elements during human definitive erythropoiesis [ChIP-seq]

In this study, we resolved the genome-wide binding of TR4 in differentiating human erythroid cells by performing chromatin immunoprecipitation followed by next-generation sequencing (ChIP-seq). We found that TR4 preferentially binds to DR1 elements in the promoters of its target genes, and that the majority of these genes encode proteins that participate in fundamental biological functions such as mRNA processing, translation, RNA splicing and primary metabolic process. Interestingly, we also found an increased occurrence of other repeat element motifs (such as DR4, IR1 and ER6) at TR4-bound distal sites that are located more than 10 Kbp away from the nearest gene. This raises the tantalizing possibility that TR4 may heterodimerize with unique partners, including other nuclear receptors such as RXR, thus allowing TR4 to elicit unique transcriptional responses when acting at proximal (promoter) and distal (enhancer and silencer) regulatory sites during human erythropoiesis.