Effects of cyclosporine A on Na,K-ATPase expression in the renal epithelial cell line NBL-1.
The bovine renal epithelial cell line NBL-1 has been used to monitor the effects of cyclosporine A (CsA) on Na+,K(+)-ATPase activity and expression. CsA at two single doses (0.6 mg/liter and 2.5 mg/liter) inhibits the ouabain-sensitive component of Rb+ uptake, assumed to be Na+,K(+)-ATPase, but increases the low activity of a furosemide-sensitive component corresponding to a Na+/K+/Cl- cotransporter. CsA addition also induces a slight decrease of alpha 1 subunit mRNA levels, without altering the already low beta 1 subunit mRNA amounts. Hypertonic treatment of NBL-1 cells leads to a significant increase in both Na+,K(+)-ATPase activity and alpha 1 subunit mRNA amounts, but does not modify beta 1 subunit mRNA levels. The differential response of the alpha 1 and beta 1 subunit genes may explain why hypertonic treatment does not result in higher alpha 1 protein expression, and supports the view that increased activity relies upon post-translational events, despite the likely transcriptional activation of the alpha 1 subunit gene. The addition of CsA does not alter the hypertonicity-mediated increase of Na+,K(+)-ATPase activity but blocks the accumulation of alpha 1 subunit mRNA. In conclusion, CsA may compromise the ion handling by renal cells as a result of the inhibition of basal Na+,K(+)-ATPase activity and the stimulation of Na+/K+/Cl- cotransport activity. Moreover, this is the first report showing that CsA may affect the long-term adaptation of the pump by altering its subunit gene expression.
Ferrer-Martínez
A
A
Departament de Bioquímica i Biologia Molecular, Universitat de Barcelona, Spain.
Felipe
A
A
Barceló
P
P
Casado
F J
FJ
Ballarín
J
J
Pastor-Anglada
M
M
D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002352:Carrier Proteins / Q000378:metabolism; D002417:Cattle; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology; D016572:Cyclosporine / Q000494:pharmacology*; D004247:DNA / Q000096:biosynthesis; D004232:Diuretics / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004848:Epithelium / Q000187:drug effects / Q000201:enzymology; D005665:Furosemide / Q000494:pharmacology; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D007668:Kidney / Q000201:enzymology*; D008565:Membrane Proteins / Q000378:metabolism; D010042:Ouabain / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis; D012413:Rubidium / Q000378:metabolism; D028021:Sodium-Potassium-Chloride Symporters; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000378:metabolism; D013936:Thymidine / Q000378:metabolism
D002352:Carrier Proteins; D004232:Diuretics; D004791:Enzyme Inhibitors; D007166:Immunosuppressive Agents; D008565:Membrane Proteins; D012333:RNA, Messenger; D028021:Sodium-Potassium-Chloride Symporters; D010042:Ouabain; D005665:Furosemide; D016572:Cyclosporine; D004247:DNA; D000254:Sodium-Potassium-Exchanging ATPase; D012413:Rubidium; D013936:Thymidine