Epithelial Vasopressin Type-2 Receptors Regulate Myofibroblasts by a YAP-CCN2-Dependent Mechanism in Polycystic Kidney Disease.

Abstract

Fibrosis is a major cause of loss of renal function in autosomal dominant polycystic kidney disease (ADPKD). In this study, we examined whether vasopressin type-2 receptor (V2R) activity in cystic epithelial cells can stimulate interstitial myofibroblasts and fibrosis in ADPKD kidneys. We treated <i>Pkd1</i> gene knockout (<i>Pkd1</i>KO) mice with dDAVP, a V2R agonist, for 3 days and evaluated the effect on myofibroblast deposition of extracellular matrix (ECM). We also analyzed the effects of conditioned media from primary cultures of human ADPKD cystic epithelial cells on myofibroblast activation. Because secretion of the profibrotic connective tissue growth factor (CCN2) increased significantly in dDAVP-treated <i>Pkd1</i>KO mouse kidneys, we examined its role in V2R-dependent fibrosis in ADPKD as well as that of yes-associated protein (YAP). V2R stimulation using dDAVP increased the renal interstitial myofibroblast population and ECM deposition. Similarly, conditioned media from human ADPKD cystic epithelial cells increased myofibroblast activation <i>in vitro</i>, suggesting a paracrine mechanism. Renal collecting duct-specific gene deletion of <i>CCN2</i> significantly reduced cyst growth and myofibroblasts in <i>Pkd1</i>KO mouse kidneys. We found that YAP regulates <i>CCN2</i>, and YAP inhibition or gene deletion reduces renal fibrosis in <i>Pkd1</i>KO mouse kidneys. Importantly, YAP inactivation blocks the dDAVP-induced increase in myofibroblasts in <i>Pkd1</i>KO kidneys. Further <i>in vitro</i> studies showed that V2R regulates YAP by an ERK1/2-dependent mechanism in human ADPKD cystic epithelial cells. Our results demonstrate a novel mechanism by which cystic epithelial cells stimulate myofibroblasts in the pericystic microenvironment, leading to fibrosis in ADPKD. The V2R-YAP-CCN2 cell signaling pathway may present a potential therapeutic target for fibrosis in ADPKD.