Background: The epithelial-mesenchymal signaling involving SHH-FOXF1, TBX4-FGF10, and TBX2 pathways is an essential transcriptional network operating during early lung organogenesis. However, precise regulatory interactions between different genes and proteins in this pathway are incompletely understood.
Methods: To identify TBX2 and TBX4 genome-wide binding sites, we performed chromatin immunoprecipitation followed by next-generation sequencing (ChIP-seq) in human fetal lung fibroblasts IMR-90.
Results: We identified 14,322 and 1,862 sites strongly-enriched for binding of TBX2 and TBX4, respectively, 43.95% and 18.79% of which are located in the gene promoter regions. Gene Ontology, pathway enrichment, and DNA binding motif analyses revealed a number of overrepresented cues and transcription factor binding motifs relevant for lung branching that can be transcriptionally regulated by TBX2 and/or TBX4. In addition, TBX2 and TBX4 binding sites were found enriched around and within FOXF1 and its antisense long noncoding RNA FENDRR, indicating that the TBX4-FGF10 cascade may directly interact with the SHH-FOXF1 signaling.
Conclusions: We highlight the complexity of transcriptional network driven by TBX2 and TBX4 and show that disruption of this crosstalk during morphogenesis can play a substantial role in etiology of lung developmental disorders.
Keywords: Lung morphogenesis; Motif enrichment; Transcriptional regulation.