Erk1/2 phosphorylation and reactive oxygen species formation via nitric oxide and Akt-1/Raf-1 crosstalk in cultured rat cerebellar granule cells exposed to the organic solvent 1,2,4-trimethylcyclohexane.
Previously, we have shown that exposure of cultured rat cerebellar granule cells to the hydrocarbon solvent 1,2,4-trimethylcyclohexane leads to formation of reactive oxygen species (ROS). However, the cellular mechanisms responsible for formation of ROS in these cells after exposure to organic solvents are poorly understood. Here, we found that 1,2,4-trimethylcyclohexane induced a time and concentration dependent dephosphorylation of Akt-1 at Ser-473 and Raf-1 at Ser-259. An increased level of phosphorylated extracellular signal-regulated kinases (Erk1/2) at Tyr-204 was observed. By use of the nitric oxide synthase inhibitors N(omega)-nitro-L-arginine methylester and diphenyleneiodonium, we found that intracellular formation of nitric oxide was necessary for phosphorylation of Erk1/2 and for the formation of ROS. Furthermore, the ROS formation was inhibited by the Erk1/2 pathway inhibitor U0126. A 1,2,4-trimethylcyclohexane (TMCH)-induced cell death was lowered by U0126 and the free radical scavenger vitamin E. Our results show that Erk1/2 kinases and nitric oxide (NO) may participate in ROS formation induced by 1,2,4-trimethylcyclohexane in cultured rat cerebellar granule cells, and also indicate a crosstalk between Akt and the Raf-Mek-Erk signaling systems.
Myhre
Oddvar
O
Norwegian Defence Research Establishment, Division for Protection and Materiel, P.O. Box 25, N-2027 Kjeller, Norway. oddvar.myhre@amersham.com
Sterri
Sigrun Hanne
SH
Bogen
Inger Lise
IL
Fonnum
Frode
F
D000818:Animals; D015153:Blotting, Western; D002070:Butadienes / Q000494:pharmacology; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology / Q000378:metabolism*; D003510:Cyclohexanes / Q000633:toxicity*; D003594:Cytoplasmic Granules / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D009570:Nitriles / Q000494:pharmacology; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D048491:Proto-Oncogene Proteins A-raf / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism*; D020239:Receptor Cross-Talk / Q000502:physiology; D012997:Solvents / Q000633:toxicity
D002070:Butadienes; D003510:Cyclohexanes; D004791:Enzyme Inhibitors; D020030:Nitric Oxide Donors; D009570:Nitriles; D011518:Proto-Oncogene Proteins; D017382:Reactive Oxygen Species; D012997:Solvents; C113580:U 0126; C069243:1,2,4-trimethylcyclohexane; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; C494920:Akt1 protein, rat; D017346:Protein Serine-Threonine Kinases; D048491:Proto-Oncogene Proteins A-raf; D051057:Proto-Oncogene Proteins c-akt; D020928:Mitogen-Activated Protein Kinases