Tetracycline-inducible gene expression in cultured rat renal CD cells and in intact CD from transgenic mice

The renal collecting duct (CD) plays a key role in the control of ion and f luid homeostasis. Several genetic diseases that involve mutations in genes encoding for ion transporters or hormone receptors specifically expressed i n CD have been described. Suitable cellular or transgenic animal models exp ressing such mutated genes in an inducible manner should represent attracti ve systems for structure-function relationship analyses and the generation of appropriate physiopathological models of related diseases. Our first goa l was to develop a CD cell line that allows inducible gene expression using the tetracycline-inducible system (Tet-On). We designed several strategies aimed at the development of a tight and highly inducible system in RCCD1 c ells, a rat cortical collecting duct (CCD) cell line exhibiting several pro perties of the native CCD. Analysis of reporter gene expression demonstrate d that the Tet-On system is suitable for inducible gene expression in these cells. In a second step, we have tested whether transgenic Tet-On mice exp ressing the tetracycline transactivator under the control of the human cyto megalovirus promoter were suitable for inducible gene expression in tubule epithelial cells. The results indicate that, in vivo, the inducible express ion of the lacZ reporter gene appeared to be restricted to the CD. This par ticular strain of transgenic mice may therefore be useful for the expressio n of genes of interest in an inducible manner in the collecting duct.