Activation of extracellular signal-regulated kinase ERK after hypo-osmotic stress in renal epithelial A6 cells

摘要

Activation of mitogen-activated protein (MAP) kinases has been reported to occur after a hypo-osmotic cell swelling in various types of cells. In renal epithelial A6 cells, the hypo-osmotic shock induced a rapid increase in the phosphorylation of an extracellular signal-regulated kinase (ERK)-like protein that was maximal 10 min after osmotic stress. Activation of ERK was significantly increased when hypo-osmotic stress was performed in the absence of extracellular Ca2+, a condition that inhibits regulatory volume decrease (RVD). Exposure of cells to PD98059, an inhibitor of the MAP kinase kinase MEK, at a concentration that fully cancelled ERK activation, did not inhibit RVD. On the contrary, RVD was abolished when osmotic shock was induced in the presence of SB203580, an inhibitor of stress-activated protein kinases (SAPKs). These results suggest that different MAP kinases are activated after hypo-osmotic stress in A6 cells. SAPKs would be involved in the control of RVD, while ERK would lead to later events, such as gene expression or energy metabolism. (C) 2004 Elsevier B.V. All rights reserved.