The goal of this project is to better define the genetic program that drives kidney formation in the embryo. While all cells carry the same complement of genes, different cell types use, or express, different sets of genes. This is similar to a computer that has a large number of programs, but only executes one or a few programs at a given time. Two computers with the same program capacity could be doing very different things at a given moment. And two cells in the embryo, with the same genes, could be doing very different things because they are using different sets of genes.
Microarrays, or gene chips, allow one to simultaneously look at all of the approximately 25,000 genes present in every cell and to determine which ones are active. Gene chips are rapid, sensitive, and quantitative. Even low levels of gene expression are detected, and numeric expression levels are defined for each gene.
The first part of this project is to use gene chips to determine the gene expression states of entire kidneys at different stages of their development in the mouse embryo. This provides a global view of all the genes used in this process. But the adult kidney is a complicated structure, with many parts, including the blood filtration unit, the glomerulus, tubules that retrieve essential elements from the filtered blood, and collecting ducts that gather the residual waste for elimination. We can learn still more about kidney formation by studying the genetic control of the development of each of these substructures.
In this project we use lasers to cut out the embryonic elements that give rise to each of these adult kidney parts. This is called laser capture microdissection. We then use gene chips to define the gene expression states of each of these purified pieces. This allows us to better understand the genetic programs that drive formation of each part of the kidney.