Raoul D. Nelson, M.D., Ph.D., Associate Professor of Pediatrics
Dr. Nelson studies regulation of gene expression within principal and intercalated cells of the collecting duct. Aquaporin-2 and the V-ATPase B1 subunit promoters have been coupled to GFP in transgenic mice to achieve principal and intercalated cell, respectively, -specific expression in vivo. Studies are underway to define the promoter elements and transcription factors responsible for cell specific gene expression. Fluorescent assisted microdissection and FACS are used to isolate collecting ducts, principal cells or intercalated cells from transgenic kidneys expressing GFP. In addition, transgenic kidneys expressing GFP are being used to develop cell culture systems. Dr. Nelson has identified candidate collecting duct specific transcription factor gene families. The epithelial Ets factors are the first group of collecting duct transcription factors under investigation. Real-time RT-PCR, in situ hybridization and immunocytochemistry are being used to define the expression of these factors in the adult and developing kidney. In addition, the reporter gene assays and chromatin immunoprecipitation assays are being used to examine the role of these factors in the regulation of collecting duct transporters such as aquaporin-2, epithelial sodium channel and V-ATPase. The epithelial Ets factors may be important in the differentiation and maturation of the collecting duct, and also potentially in diseases of the collecting duct.
Knowledge about collecting duct specific gene expression is being used to develop principal and intercalated cell specific gene targeting systems. The aquaporin-2 promoter has already been used to drive expression of Cre recombinase in transgenic mice. These transgenic mice are being used to constitutively delete genes in principal cells. One such application that is currently underway is to delete PKD1 in principal cells of the collecting duct in attempts to develop a non-lethal mouse model of polycystic kidney disease. The V-ATPase B1 subunit promoter is currently being employed to drive the expression of Cre recombinase or rtTA intercalated cells of transgenic mice. These transgenic mice will be used to achieve constitutive and temporal regulated deletion of genes in the intercalated cells. One such application of this system will be to delete the V-ATPase in intercalated cells.
