The Manton Center for Orphan Disease Research
Joanne Chan, PhD
Vascular Dissection of TSC/LAM Progression in a Zebrafish Model
Tuberous Sclerosis Complex, TSC, is a rare hereditary disease that can be diagnosed in utero or at infancy due to mutations in 2 genes (TSC1, TSC2) that function together. TSC children have multiple system defects including neurological disorders and predisposition to a number of benign tumors as they age. Among these tumors is a rare kidney tumor found in TSC children at about 5-6 years of age. In the general population, these tumors occur at about 58 years of age. A major complication is that these tumors are highly vascularized and can rupture. However, early removal of the tumors will also remove kidney function so that young children would need dialysis or kidney transplants. Recently, mutations in the same genes were found in another rare disease called LAM, where young women are mostly affected. They are diagnosed from reduced lung function but also frequently have the same benign kidney tumors as TSC children. One common aspect of these 2 diseases is that the mutations in these Tsc1/2 genes lead to overactive mTOR kinase activity affecting many cell types. My hypothesis for this study is that these mutations also increase the levels of the vascular endothelial growth factor, a robust stimulator of blood vessel formation. Through this common ability to increase nutrient and oxygen to benign tumors, these tumors continue to enlarge and threaten organ function. This proposal uses the zebrafish as a model system to investigate these ideas. The zebrafish embryo is transparent and blood vessels can be clearly visualized. By altering the levels of mTOR kinase activity and VEGF levels, we hope to further our understanding of the mechanisms common to both TSC and LAM and provide insights into potential earlier intervention.