Phenotypic effects of aldosterone and dexamethasone in a SV40-transformed mammalian cortical ascending limb cell line exhibiting mineralocorticoid receptors.
We have analyzed the functional and morphological effects of corticosteroid hormones in a SV40-transformed rabbit cortical-ascending-limb (CAL) cell line (RC.SV2, Vandewalle et al., 1989) having mineralocorticoid (MR) and glucocorticoid (GR) receptors (Rafestin-Oblin et al., 1993). Both aldosterone and dexamethasone (5 x 10(-8) M) induced a marked increase in (3H)ouabain binding (used to quantify membrane Na(+)-K+ ATPase) detectable as early as 6 hours and maximal at 24 hours (+56-57%) (due to a 1.6-1.8-fold increase in cell membrane binding sites without Kd alteration), and significantly augmented the ouabain-sensitive component of Rb+ influx. Triiodothyronine (T3, 10(-9) M) also stimulated ouabain binding by 21% but was not permissive for steroid action, whereas 5 micrograms/ml insulin had no effect. Both steroid hormones, T3 and insulin induced the formation of domes that was tightly correlated with ouabain binding (r = 0.949) except for insulin. The effects of aldosterone and dexamethasone on cell monolayers and cell ultrastructure were, however, strikingly different as aldosterone induced a marked amplification of basolateral areas with appearance of large intercellular spaces, reminiscent of the changes observed in deoxycorticosterone-treated rats, whereas dexamethasone predominantly influenced cell height. This discrepancy might be due to specific occupancy of MR and GR by aldosterone and dexamethasone, respectively, and/or to nongenomic effects of dexamethasone. We have thus characterized a cell culture model making it possible to analyze the actions of mineralocorticoid and glucocorticoid hormones in the mammalian kidney.
INSERM U.246, UER Xavier Bichat, Paris, France.
A
A
Vandewalle
M E
ME
Rafestin-Oblin
J
J
Hagege
M
M
Géniteau-Legendre
R
R
Cassingéna
P M
PM
Ronco
D000305:Adrenal Cortex Hormones / Q000032:analysis / Q000378:metabolism; D000450:Aldosterone / Q000494:pharmacology*; D000818:Animals; D002461:Cell Line, Transformed; D003907:Dexamethasone / Q000494:pharmacology*; D007328:Insulin / Q000494:pharmacology; D007686:Kidney Tubules, Distal / Q000737:chemistry* / Q000166:cytology* / Q000648:ultrastructure; D008854:Microscopy, Electron; D010042:Ouabain / Q000378:metabolism; D010641:Phenotype; D011817:Rabbits; D018161:Receptors, Mineralocorticoid; D011987:Receptors, Steroid / Q000032:analysis* / Q000378:metabolism; D012413:Rubidium; D013539:Simian virus 40 / Q000502:physiology*; D000254:Sodium-Potassium-Exchanging ATPase / Q000032:analysis / Q000187:drug effects / Q000502:physiology; D014284:Triiodothyronine / Q000494:pharmacology
D000305:Adrenal Cortex Hormones; D007328:Insulin; D018161:Receptors, Mineralocorticoid; D011987:Receptors, Steroid; D014284:Triiodothyronine; D000450:Aldosterone; D010042:Ouabain; D003907:Dexamethasone; D000254:Sodium-Potassium-Exchanging ATPase; D012413:Rubidium