Overexpression of PKD2 in the mouse is associated with renal tubulopathy

Polycystin-2 (PC-2), a cation channel of the Trp family, is involved in autosomal dominant polycystic kidney disease ( ADPKD) type 2 (ADPKD2). This protein has recently been localized to the primary cilium where its channel function seems to be involved in a mechanosensory phenomenon. However, its biological function is not totally understood, especially in tubule formation. In the present paper, we describe a mouse model for human PC-2 overexpression, obtained by inserting a human bacterial artificial chromosome (BAC) containing the PKD2 gene. Three lines were generated, expressing different levels of PKD2. One line, PKD2-Y, has been explored in more detail and we will present physiological and molecular exploration of these transgenic animals. Our data demonstrate that transgenic animals older than 12 months present tubulopathy with proteinuria and failure to concentrate urine. Moreover, the kidney cortex has been found disorganized. Finally, we observe that extracellular matrix protein expression is downregulated in these animals. In conclusion, overexpression of human PKD2 leads to anomalies in tubular function, probably due to abnormalities in tubule morphogenesis.