title: Hydrogen peroxide activates p70(S6k) signaling pathway.
abstract: We investigated a possible role of reactive oxygen species (ROS) in p70(S6k) activation, which plays an important role in the progression of cells from G(0)/G(1) to S phase of the cell cycle by translational up-regulation of a family of mRNA transcripts that encode for components of the protein synthetic machinery. Treatment of mouse epidermal cell JB6 with H(2)O(2) generated extracellularly by glucose/glucose oxidase led to the activation of p70(S6k) and p90(Rsk) and to phosphorylation of p42(MAPK)/p44(MAPK). The activation of p70(S6k) and p90(Rsk) was dose-dependent and transient, maximal activities being in extracts treated for 15 and 30 min, respectively. Further characterization of ROS-induced activation of p70(S6k) using specific inhibitors for p70(S6k) signaling pathway, rapamycin, and wortmannin revealed that ROS acted upstream of the rapamycin-sensitive component FRAP/RAFT and wortmannin-sensitive component phosphatidylinositol 3-kinase, because both inhibitors caused the inhibition of ROS-induced p70(S6k) activity. In addition, Ca(2+) chelation also inhibited ROS-induced activation of p70(S6k), indicating that Ca(2+) is a mediator of p70(S6k) activation by ROS. However, down-regulation of 12-O-tetradecanoylphorbol-13-acetate (TPA)-responsive protein kinase C (PKC) by chronic pretreatment with TPA or a specific PKC inhibitor Ro-31-8220 did not block the activation of p70(S6k) by ROS, indicating that the activation of TPA-responsive PKC was not required for stimulation of p70(S6k) activity by H(2)O(2) in JB6 cells. Exposure of JB6 cells to platelet-derived growth factor or epidermal growth factor led to a rapid increase in H(2)O(2), phosphorylation, and activation of p70(S6k), which were antagonized by the pretreatment of catalase. Taken together, the results suggest that ROS act as a messenger in growth factor-induced p70(S6k) signaling pathway.
authors.affiliation: Department of Biochemistry, College of Pharmacy, Sungkyunkwan University, Suwon 440-746, Korea.
authors.forename: G U
authors.initials: GU
authors.lastname: Bae
authors.forename: D W
authors.initials: DW
authors.lastname: Seo
authors.forename: H K
authors.initials: HK
authors.lastname: Kwon
authors.forename: H Y
authors.initials: HY
authors.lastname: Lee
authors.forename: S
authors.initials: S
authors.lastname: Hong
authors.forename: Z W
authors.initials: ZW
authors.lastname: Lee
authors.forename: K S
authors.initials: KS
authors.lastname: Ha
authors.forename: H W
authors.initials: HW
authors.lastname: Lee
authors.forename: J W
authors.initials: JW
authors.lastname: Han
mesh_terms: D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002374:Catalase / Q000494:pharmacology; D002460:Cell Line; D004789:Enzyme Activation; D004815:Epidermal Growth Factor / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D007211:Indoles / Q000494:pharmacology; D051379:Mice; D008807:Mice, Inbred BALB C; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010766:Phosphorylation; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D017382:Reactive Oxygen Species / Q000378:metabolism; D019893:Ribosomal Protein S6 Kinases / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D020123:Sirolimus / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D000077191:Wortmannin
chemical_list: D000730:Androstadienes; D007211:Indoles; D010982:Platelet-Derived Growth Factor; D017382:Reactive Oxygen Species; D004815:Epidermal Growth Factor; D006861:Hydrogen Peroxide; D002374:Catalase; D019893:Ribosomal Protein S6 Kinases; D011493:Protein Kinase C; D020928:Mitogen-Activated Protein Kinases; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium; D020123:Sirolimus; C064758:Ro 31-8220; D000077191:Wortmannin