Ouabain promotes partial epithelial to mesenchymal transition (EMT) changes in human autosomal dominant polycystic kidney disease (ADPKD) cells

Abstract

The hormone ouabain has been shown to enhance the cystic phenotype of autosomal dominant polycystic kidney disease (ADPKD). Among other characteristics, the ADPKD phenotype includes cell de-differentiation and epithelial to mesenchymal transition (EMT). Here, we determined whether physiological concentrations of ouabain induces EMT in human renal epithelial cells from patients with ADPKD. We found that ADPKD cells respond to ouabain with a decrease in expression of the epithelial marker E-cadherin and increase in the expression of the mesenchymal markers N-cadherin, α smooth muscle actin (αSMA) and collagen-I; and the tight junction protein occludin and claudin-1. Other adhesion molecules, such as ZO-1, β-catenin and vinculin were not significantly modified by ouabain. At the cellular level, ouabain stimulated ADPKD cell migration, reduced cell-cell interaction, and the ability of ADPKD cells to form aggregates. Moreover, ouabain increased the transepithelial electrical resistance of ADPKD cell monolayers, suggesting that the paracellular transport pathway was preserved in the cells. These effects of ouabain were not observed in normal human kidney (NHK) cells. Altogether these results show a novel role for ouabain in ADPKD, inducing changes that lead to a partial EMT phenotype in the cells. These effects further support the key role that ouabain has as a factor that promotes the cystic characteristics of ADPKD cells.

Telocinobufagin and Marinobufagin Produce Different Effects in LLC-PK1 Cells: A Case of Functional Selectivity of Bufadienolides

“…Moreover, Wnt/β-catenin activation through constitutively active β-catenin or dnTCF4 VP16 were not blocked by the bufadienolide, suggesting that telocinobufagin acts upstream to β-catenin stabilization. Recently, some CTS have been demonstrated to inhibit Wnt/β-catenin signaling in tumor cells [ 78 , 83 , 84 ] but, on the other hand, in renal cells, CTS have been reported to promote EMT [ 85 , 86 ] and β-catenin nuclear translocation [ 87 ]. Further studies are definitely necessary to characterize the mechanism(s) of action involved in telocinobufagin-induced LLC-PK1 cell death.…”

Proteomic analysis of AQP11-null kidney: Proximal tubular type polycystic kidney disease

“…Another interesting observation in this study was decreased cadherin and increased fibronectin in AQP11-null kidneys. Both are markers for epithelial-mesenchymal transition (EMT) [24] , [25] , [26] , [27] , which has been shown to be associated with kidney cyst formation in ADPKD and pck rats [28] , [29] , [30] . Moreover, proteins related to wound healing such as fibronectin1 and Ptk7 were also induced in AQP11-null kidneys.…”

Circulating Ouabain Modulates Expression of Claudins in Rat Intestine and Cerebral Blood Vessels

“…Previously, in cell cultures, effects of nanomolar ouabain concentrations on claudin-1, -2, -4 and -11 expression were investigated [ 20 , 21 , 22 ]. In this study, we used the porcine jejunum cell line IPEC-J2 [ 31 ] to test the effect of nanomolar ouabain on the expression of a broad range of claudins.…”

“…However, studies on cultured cells indicate its additional role in formation of tight junctions (TJ) and in regulation of TJ structure and permeability via the Na,K-ATPase-mediated modulation of claudin expression. Ouabain serves as the main pharmacological tool in these studies [ 20 , 21 , 22 ]. Claudins (27 family members) are integral proteins in the plasma membrane that form the TJ and determine paracellular permeability and barrier properties of epithelium, endothelium and mesothelium [ 23 , 24 , 25 ].…”