Activation of the MAPKs ERK1/2 by cell swelling in turbot hepatocytes

• Published in: Biology of the Cell
• Main Authors: Fouchs, Audrey, Ollivier, Hélène, Haond, Christophe, Roy, Stella, Calvès, Patrick, Pichavant‐Rafini, Karine
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2010
• Subjects: Mek; Turbot
• Online Access: http://dx.doi.org/10.1042/bc20090154; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1042%2FBC20090154; https://onlinelibrary.wiley.com/doi/pdf/10.1042/BC20090154

Background information . Activation of MAPKs (mitogen‐activated protein kinases), in particular ERK1/2 (extracellular‐signal‐regulated kinase 1/2), has been reported to take place in a large variety of cell types after hypo‐osmotic cell swelling. Depending on cell type, ERK1/2 phosphorylation can then serve or not the RVD (regulatory volume decrease) process. The present study investigates ERK1/2 activation after aniso‐osmotic stimulations in turbot hepatocytes and the potential link between phosphorylation of these proteins and RVD. Results . In turbot hepatocytes, Western‐blot analysis shows that a hypo‐osmotic shock from 320 to 240 mOsm·kg −1 induced a rapid increase in ERK1/2 phosphorylation, whereas a hyper‐osmotic shock from 320 to 400 mOsm·kg −1 induced no significant change in the phosphorylation of these proteins. The hypo‐osmotic‐induced ERK1/2 phosphorylation was significantly prevented when hypo‐osmotic shock was performed in the presence of the specific MEK (MAPK/ERK kinase) inhibitor PD98059 (100 μM). In these conditions, the RVD process was not altered, suggesting that ERK1/2 did not participate in this process in turbot hepatocytes. Moreover, the hypo‐osmotic‐induced activation of ERK1/2 was significantly prevented by breakdown of extracellular ATP by apyrase (10 units·ml −1 ), by inhibition of purinergic P 2 receptors by suramin (100 μM) or by calcium depletion using EGTA (1 mM) and thapsigargin (1 μM). Conclusions . In turbot hepatocytes, hypo‐osmotic swelling but not hyper‐osmotic shrinkage induced the activation of ERK1/2. However, these proteins do not seem to be involved in the RVD process. Their hypo‐osmotic‐induced activation is partially due to cascades of signalling events triggered by the binding of released ATP on purinergic P 2 receptors and requires the presence of calcium.