Systematic Identification of Ftz and Ftz-F1 Responsive Target Genes and Their Enhancers. Amanda Field¹, Ray Anderson¹, Jie Xang¹, Leslie Pick^1,2. 1) Program in Molecular & Cell Biology, University of Maryland, College Park, MD; 2) Department of Entomology, University of Maryland, College Park, MD.

   Fushi tarazu (Ftz) and its obligate cofactor Ftz-F1 cooperatively bind to DNA and co-regulate the transcription of genes responsible for segmentation in the early embryo. Ftz is a homeodomain protein which binds DNA promiscuously, whereas Ftz-F1 is an orphan nuclear receptor with a well characterized DNA binding sequence. To identify the range of targets regulated by Ftz/Ftz-F1, a microarray analysis was performed comparing blastoderm/gastrulation stage wild type and ftz-f1 mutant embryos. This resulted in a short list of candidate targets that were downregulated in the absence of Ftz-F1 protein. The microarray data was combined with the blastoderm staged ChIP-chip data sets, generated by the BDTNP, showing where Ftz protein is bound in the genome. This combination produced a testable list of novel candidate Ftz/Ftz-F1 target enhancers near the genes of interest from the microarray. To test whether these regions correspond to Ftz/Ftz-F1-dependent enhancers, reporter genes were constructed in which these genomic regions are fused upstream of a basal promoter and E. coli lacZ. Reporter gene expression was analyzed in wild type, ftz and ftz-f1 mutant transgenic Drosophila. Once Ftz-responsive enhancer regions are well defined, this will be used to computationally extract the code for Ftz/Ftz-F1 DNA binding.