Uncovering gene regulatory network in limb development

My PhD work at UIC is focused on identifying regulatory interactions between genes that are involved in limb development. This is an image of a genetically mosaic Drosophila leg in prepupal stage that lacks the function of a conserved transcriptional cofactor called dachshund (dac). The human homolog of dac, DACH1, is involved in tumorigenesis and has been reported to have altered expression profile in cancer patients. The image reveals, for the first time, dac regulates the expression of two key developmental genes Hox gene Sex combs reduced (Scr) and bric à brac (bab). It is known that spatially defined Hox gene expression is crucial for the development of organs and tissues at precise positions along the body axis of animals. Loss of dac, marked by lack of green fluorescent protein, resulted in ectopic bab expression (blue circles) and loss of the Hox gene Scr throughout the leg tissue (absence of red color within the blue regions). This finding provides a key to understand the complex genetic networks that are responsible for limb development and sheds light on the conserved nature of regulatory interactions among developmental genes that are co-opted in different biological systems.