Cell & Developmental Biology
Cancer Cell Biology
Area of interest
Work in my laboratory focuses on the biology of RNAi. This biological pathway is becoming increasingly popular as a genetic tool. It is particularly valuable in mammalian cultured cells, where 'loss of function' methods were previously very restricted. Separate from its practical uses, the biology of RNAi is only beginning to be understood. This includes the exciting discovery that RNAi is used by cells to regulate their own genes. I am designing my laboratory to study key components of the biology of RNAi, and to explore new applications of this powerful technology.
Broadly speaking, I am pursuing three major lines of investigation:
1. Mechanistic study of RNAi.
My project as a postdoctoral associate in Greg Hannon's laboratory was a biochemical investigation into the mechanism of RNAi. In particular, we identified a Fragile X family member as a component of the RNAi machinery, raising the possibility that RNAi deficiency results in this Human disease. My independent laboratory is continuing biochemical studies on this RNAi/Fragile X complex. Specifically, we will characterize the role of RNAi components in the function of the Fragile X complex, and the role of Fragile X proteins in RNAi mediated gene knockdown. Weare working to understand the makeup of this common, RNAi/Fragile X complex, and how this makeup affects specificity of Fragile X regulated genes.
2. Cellular regulation by RNAi and microRNAs.
In C. elegans, Drosophila, and plants, microRNAs have been shown to play essential roles in gene regulation. Little is known about microRNA function in human cells. My laboratory is developing several genomic methods for analyzing microRNA function. We are particularly interested in growth control and transformation. We have identified several microRNAs that are correlated with tumorigenesis, and have functionally validated them in mouse lymphomagenesis models. We also plan to use microRNA overexpression libraries for phenotype driven screens, for the purpose of identifying key microRNAs involved in growth control and tumorigenesis.
3. Applications of RNAi to mammalian genetics.
The discovery of mammalian RNAi methods has enabled 'loss of function' studies in cultured cells. The typical application of this technology is for reverse genetics; that is, for knockdown of specific genes that are expected to be involved in a particular biologic process. Libraries of RNAi knockdown constructs that target approximately 8000 human genes are available to the research community. I am using this library to identify genes essential for angiogenic processes in cultured cells. It is my expectation that these essential genes will represent anti-angiogenic anti-cancer drug targets. In a parallel project, my laboratory is developing a mouse model system that uses RNAi in vivo to validate genes essential for tumor formation. Positive hits from the in vitro library screen will be tested in the mouse model. In addition, a set of approximately 50 genes previously implicated in pathological angiogenesis and tumor metastasis will be directly tested in the in vivo model. My long term goal is to perform knockdown library screens using this mouse model system to identify all possible anti-cancer drug targets.