Hyperosmotic and isosmotic shrinkage differentially affect protein phosphorylation and ion transport.
In the present work, we compared the outcome of hyperosmotic and isosmotic shrinkage on ion transport and protein phosphorylation in C11-MDCK cells resembling intercalated cells from collecting ducts and in vascular smooth muscle cells (VSMC) from the rat aorta. Hyperosmotic shrinkage was triggered by cell exposure to hypertonic medium, whereas isosmotic shrinkage was evoked by cell transfer from an hypoosmotic to an isosmotic environment. Despite a similar cell volume decrease of 40%-50%, the consequences of hyperosmotic and isosmotic shrinkage on cellular functions were sharply different. In C11-MDCK and VSMC, hyperosmotic shrinkage completely inhibited Na(+),K(+)-ATPase and Na(+),P(i) cotransport. In contrast, in both types of cells isosmotic shrinkage slightly increased rather than suppressed Na(+),K(+)-ATPase and did not change Na(+),P(i) cotransport. In C11-MDCK cells, phosphorylation of JNK1/2 and Erk1/2 mitogen-activated protein kinases was augmented in hyperosmotically shrunken cells by ∼7- and 2-fold, respectively, but was not affected in cells subjected to isosmotic shrinkage. These results demonstrate that the data obtained in cells subjected to hyperosmotic shrinkage cannot be considered as sufficient proof implicating cell volume perturbations in the regulation of cellular functions under isosmotic conditions.
Research Centre, Centre hospitalier de l'Université de Montréal - Technopôle Angus, Montreal, QC H1W 4A4, Canada.
Svetlana V
SV
Koltsova
Olga A
OA
Akimova
Sergei V
SV
Kotelevtsev
Ryszard
R
Grygorczyk
Sergei N
SN
Orlov
D000818:Animals; D001011:Aorta / Q000378:metabolism / Q000473:pathology; D048429:Cell Size; D004285:Dogs; D004847:Epithelial Cells / Q000473:pathology*; D017136:Ion Transport; D007685:Kidney Tubules, Collecting / Q000378:metabolism* / Q000473:pathology; D007700:Kinetics; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D048055:Mitogen-Activated Protein Kinase 8 / Q000378:metabolism; D048056:Mitogen-Activated Protein Kinase 9 / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000378:metabolism* / Q000473:pathology; D032389:Myocytes, Smooth Muscle / Q000378:metabolism* / Q000473:pathology; D009997:Osmotic Pressure; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D051381:Rats; D050608:Sodium-Phosphate Cotransporter Proteins / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*
D050608:Sodium-Phosphate Cotransporter Proteins; D048056:Mitogen-Activated Protein Kinase 9; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048055:Mitogen-Activated Protein Kinase 8; D000254:Sodium-Potassium-Exchanging ATPase