Osmotic swelling-induced activation of the extracellular-signal-regulated protein kinases Erk-1 and Erk-2 in intestine 407 cells involves the Ras/Raf-signalling pathway.
Human Intestine 407 cells respond to hypo-osmotic stress with a rapid stimulation of compensatory ionic conductances accompanied by a transient increase in the activity of the extracellular-signal-regulated protein kinases Erk-1 and Erk-2. In this study, we examined the upstream regulators of hypotonicity-induced Erk-1/Erk-2 activation and their possible role in cell-volume regulation. The hypotonicity-provoked Erk-1/Erk-2 activation was greatly reduced in cells pretreated with the specific mitogen-activated/Erk-activating kinase inhibitor PD098059 and was preceded by a transient stimulation of Raf-1. Pretreatment of the cells with PMA, GF109203X, wortmannin or Clostridium botulinum C3 exoenzyme did not appreciably affect the hypotonicity-provoked Erk-1/Erk-2 stimulation, suggesting the osmosensitive signalling pathway to be largely independent of protein kinase C and p21(rho). In contrast, expression of dominant negative RasN17 completely abolished the hypotonicity-induced Erk-1/Erk-2 activation. Stimulation of the swelling-induced ion efflux was independent of activation of these mitogen-activated protein kinases, as revealed by hypotonicity-provoked isotope efflux from 125I-- and 86Rb+-loaded cells after pretreatment with PD098059 and after expression of RasN17. In addition, the epidermal-growth-factor-induced potentiation of the hypotonicity-provoked anionic response did not depend on the increase in Erk-1/Erk-2 activity but, instead, was found to depend on Ca2+ influx. Taken together, these results indicate that hypotonic stress induces Erk-1/Erk-2 activation through the Ras/Raf-signalling pathway, and argue against a direct role for this pathway in cell-volume control.
van der Wijk
T
T
Department of Biochemistry, Cardiovascular Research Institute COEUR, Faculty of Medicine and Health Sciences, Erasmus University, P.O. Box 1738, 3000 DR Rotterdam, The Netherlands. vanderwijk@bc1.fgg.eur.nl
Dorrestijn
J
J
Narumiya
S
S
Maassen
J A
JA
de Jonge
H R
HR
Tilly
B C
BC
D036002:ADP Ribose Transferases / Q000494:pharmacology; D000730:Androstadienes / Q000494:pharmacology; D001905:Botulinum Toxins; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000494:pharmacology*; D002460:Cell Line; D048429:Cell Size / Q000187:drug effects; D004789:Enzyme Activation / Q000502:physiology; D004815:Epidermal Growth Factor / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D006801:Humans; D007038:Hypotonic Solutions / Q000494:pharmacology; D007211:Indoles / Q000494:pharmacology; D007422:Intestines / Q000201:enzymology*; D007457:Iodine Radioisotopes / Q000378:metabolism; D008301:Maleimides / Q000494:pharmacology; D009997:Osmotic Pressure; D010766:Phosphorylation; D012414:Rubidium Radioisotopes / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D000077191:Wortmannin; D018631:ras Proteins / Q000502:physiology*
D000730:Androstadienes; D005419:Flavonoids; D007038:Hypotonic Solutions; D007211:Indoles; D007457:Iodine Radioisotopes; D008301:Maleimides; D012414:Rubidium Radioisotopes; D004815:Epidermal Growth Factor; D036002:ADP Ribose Transferases; C063007:exoenzyme C3, Clostridium botulinum; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D001905:Botulinum Toxins; D018631:ras Proteins; C070515:bisindolylmaleimide I; D013755:Tetradecanoylphorbol Acetate; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; D000077191:Wortmannin