Aldosterone Induces the Proliferation of Renal Tubular Epithelial Cells In Vivo but Not In Vitro

Abstract

Objective. To investigate the proliferation effect of aldosterone on renal tubular epithelial cells in vivo and in vitro. Methods. Thirty-two male C57BL/6J mice (20–22 g) were divided randomly into four groups: sham, unilateral nephrectomy (UN), unilateral nephrectomy plus aldosterone infusion (UA), and UA plus eplerenone (UAE). The kidneys were removed 6 weeks after treatment. Expression of proliferating cell nuclear antigen (PCNA) was detected by immunohistochemistry and western blotting. Human kidney proximal tubular epithelial (HK2) and mouse distal convoluted tubule (mDCT) cell lines were stimulated by aldosterone (0, 10−9, 10−8, 10−7, and 10−6 mol/L) in vitro. Cells were collected after 3, 6, 12, 24, 36, and 48 h, and proliferation of each group detected by western blotting, flow cytometry, live imaging, and the MTT assay. In addition, mDCT cells were costimulated with a medium containing a final concentration of 161 mmol/L Na+ and different concentrations of aldosterone, and the number of cells and cellular DNA content was measured by the MTT assay and flow cytometry. Results. Aldosterone could induce a significant increase in the number of PCNA-positive cells in mouse kidneys accompanied by increased deposition of collagen fibers. Eplerenone could inhibit aldosterone-induced cell proliferation and collagen deposition. HK2 cells and mDCT cells administered different concentrations, and different times of aldosterone stimulation failed to cause cell proliferation, and costimulation of aldosterone and salt did not cause proliferation changes in mDCT cells. Conclusions. Aldosterone perfusion can induce proliferation of mouse kidney cells in vivo, and eplerenone can inhibit this change, but aldosterone stimulates HK2 cells and mDCT in vitro without causing their proliferation.

Dietary sodium alters aldosterone's effect on renal sodium transporter expression and distal convoluted tubule remodelling

“…Both aldosterone and blood K + have been shown to drive changes in the architecture of the distal tubule. Aldosterone remodelling of the renal tubule is associated with cellular hypertrophy (Komarynets et al., 2020; Wade et al., 1990) and increased proliferation (Hao et al., 2021). Low blood [K + ] in the setting of a low K + diet leads to lengthening of the DCT and is a mechanism by which total NCC expression increases under conditions of hypokalaemia to help limit K + efflux (Saritas et al., 2018).…”

“…This leads to a lower intracellular [Cl − ], activation of with-no-lysine kinases (WNKs), and phosphorylation and activation of Ste20-related proline-alanine-rich kinase (SPAK) and oxidative stress-responsive gene 1 (OSR1) (Terker et al, 2015;Terker, Zhang, et al, 2016). This cascade ultimately induces phosphorylation and activation of NCC at several serine and threonine residues that increases its activity and surface expression (Chen et al, 2019;Hadchouel et al, 2016;Hossain Khan et al, 2012). Although some studies suggest that [K + ] is the major mediator of these alterations (Kristensen et al, 2022;Terker, Yarbrough, et al, 2016), aldosterone may also directly influence NCC expression by increasing expression of the WNK-SPAK/OSR1 pathway (Roy et al, 2015).…”