Over-expression of DREF in the Drosophila wing imaginal disc induces apoptosis and a notching wing phenotype.

Abstract

DNA replication-related element binding factor (DREF) has been suggested to be involved in regulation of DNA replication- and proliferation-related genes in Drosophila. While the effects on the mutation in the DNA replication-related element (DRE) in cultured cells have been studied extensively, the consequences of elevating wild-type DREF activity in developing tissues have hitherto remained unclear. We over-expressed DREF in the wing imaginal disc using a GAL4-UAS targeted expression system in Drosophila. Over-expression of DREF induced a notching wing phenotype, which was associated with ectopic apoptosis. A half reduction of the reaper, head involution defective and grim gene dose suppressed this DREF-induced notching wing phenotype. Furthermore, this was also the case with co-expression of baculovirus P35, a caspase inhibitor. In addition, over-expression of the 32 kDa boundary element-associated factor (BEAF-32), thought to compete against DREF for common binding sites in genomic regions, rescued the DREF-induced notching wing phenotype, while a half reduction of the genomic region, including the BEAF-32 gene, exerted enhancing effects. To our knowledge, this is the first evidence for a genetic interaction between DREF and BEAF-32. The DREF-induced notching wing phenotype is caused by induction of apoptosis in the Drosophila wing imaginal disc.