We used the fruitfly, Drosophila melanogaster, to understand how cells learn where they are in the body and how they use that information to make the correct structure. Flies are a good model system because we can easily knock out the function of one gene at a time, and then see how the fly develops without the protein produced by that gene. A mutation disrupting a single gene can have a big effect on the final pattern of the animal. This tells us that the broken gene is an important part of the information system that cells use. For example, the left and middle images in the header are normal fly embryos at early (left) and late (center) stages of development. The embryo at the right is a late stage embryo that has no functional Wnt protein. Without Wnt, the fly can’t properly pattern its heart, gut, nervous system, skin, and many other tissues. This is true in humans, too: Wnt mutations are associated with birth defects. We used genetic tricks to figure out the mechanics of Wnt gene activity in the fly (below, left), and then tested human cells (below, right) to see if it all works the same way there. That’s not just important for understanding embryonic patterning and birth defects, it is also useful for understanding human cancers, which can arise if Wnts accidentally get reactivated in adults. The more we learn about how Wnts work, the better tools we will have for diagnosing and treating this lethal disease.
Fruitfly (Drosophila melanogaster) Human cells in culture (at higher magnification)