Ouabain-stimulated trafficking regulation of the Na/K-ATPase and NHE3 in renal proximal tubule cells

Abstract

We have demonstrated that ouabain regulates protein trafficking of the Na/K-ATPase α1 subunit and NHE3 (Na/H exchanger, isoform 3) via ouabain-activated Na/K-ATPase signaling in porcine LLC-PK1 cells. To investigate whether this mechanism is species-specific, ouabain-induced regulation of the α1 subunit and NHE3 as well as transcellular 22Na+ transport were compared in three renal proximal tubular cell lines (human HK-2, porcine LLC-PK1, and AAC-19 originated from LLC-PK1 in which the pig α1 was replaced by ouabain-resistant rat α1). Ouabain inhibited transcellular 22Na+ transport due to an ouabain-induced redistribution of the α1 subunit and NHE3. In LLC-PK1 cells, ouabain also inhibited the endocytic recycling of internalized NHE3, but has no significant effect on recycling of endocytosed α1 subunit. These data indicated that the ouabain-induced redistribution of the α1 subunit and NHE3 is not a species-specific phenomenon, and ouabain-activated Na/K-ATPase signaling influences NHE3 regulation.

Involvement of Reactive Oxygen Species in a Feed-forward Mechanism of Na/K-ATPase-mediated Signaling Transduction

“…In LLC-PK1 cells, a low concentration of ouabain (up to 100 nM, about 1/10th of IC 50 ) does not inhibit 86 Rb ϩ uptake nor alter intracellular Na ϩ concentration when administered for up to 15 min (13, 47), but it does inhibit 86 Rb ϩ and Na ϩ uptake when administered for longer periods as we reported previously (13,47,48), due to ouabain-induced Na/K-ATPase endocytosis via Na/KATPase signaling (11,13,21,47,48). In LLC-PK1 cells, ouabain (1 h)-induced inhibition of transepithelial 22 Na ϩ flux is mostly dependent on the coordinated regulation of Na/K-ATPase and NHE3 through Na/K-ATPase signaling (13,21,47). Ouabain induced redistribution of Na/K-ATPase and NHE3 in LLC-PK1 cells, with a resultant reduction in cell surface levels of both transporters to depress apical Na ϩ entry through NHE3 (and other Na ϩ -coupled Na ϩ transporters) and basolateral Na ϩ extrusion through Na/K-ATPase.…”

Expression of lymphocyte coding genes in peripheral blood and lymphocyte infiltration in cardiac tissues influenced by cyclosporin A in heterotopic heart transplantation model in rats

“…We hypothesized that these genes take part in energy metabolism in T cell activation [27]. Ribosomal protein S25 is involved in P53-induced apoptosis during acute rejection [28][29][30].…”

Airway surface liquid volume expansion induces rapid changes in amiloride-sensitive Na+transport across upper airway epithelium-Implications concerning the resolution of pulmonary edema

“…1993; Yan et al. 2012). This cell culture insert system allows selective access to the basolateral and apical surfaces of the cells.…”