E2F and GATA switches turn off WD repeat domain 77 expression in differentiating cells

WDR77 (WD repeat domain 77) is expressed during earlier lung development when cells are rapidly proliferating, but is absent from adult lung. It is re-activated during lung tumorigenesis and is essential for lung cancer cell proliferation. Signalling pathways/molecules that control WDR77 gene expression are unknown. Promoter mapping, gel shift assay and ChIP revealed that the WDR77 promoter contains bona fide response elements for E2F and GATA transcriptional factors as demonstrated in prostate cancer, lung cancer and erythroid cells, as well as in mouse lung tissues. The WDR77 promoter is transactivated by E2F1, E2F3, GATA1 and GATA6, but suppressed by E2F6, GATA1 and GATA3 in prostate cancer PC3 cells. WDR77 expression is associated with E2F1, E2F3, GATA2 and GATA6 occupancy on the WDR77 gene, whereas, in contrast, E2F6, GATA1 and GATA3 occupancy is associated with the loss of WDR77 expression during erythroid maturation and lung development. More importantly, the loss of WDR77 expression that results from E2F and GATA switches is required for cellular differentiation of erythroid and lung epithelial cells. In contrast, lung cancer cells avoid post-mitotic differentiation by sustaining WDR77 expression. Altogether, the present study provides a novel molecular mechanism by which WDR77 is regulated during erythroid and lung development and lung tumorigenesis.