title: IL2-dependent phosphorylation of 40S ribosomal protein S6 is controlled by PI-3K/mTOR signalling in CTLL2 cells.
abstract: Growth factors and hormones activate global and selective protein translation by phosphorylation and therefore activation of p70 S6 kinase through a wortmannin-sensitive phosphoinositide-3 kinase (PI-3K) antiapoptotic pathway and a rapamycin-sensitive signalling pathway of mTOR. Here we demonstrate that the phosphorylation of 40S ribosomal protein S6, a physiological substrate p70 S6 kinase, was highly increased by growth-stimulation of the cytolytic T cells (CTLL2) with interleukin 2 (IL2), which was accompanied with the increased phosphorylation of p70 S6K. The activity of p70 S6K and phosphorylation of the S6 protein was completely blocked by rapamycin and significantly decreased upon treatment of the cells with wortmannin, indicating an involvement of the PI-3K pathway in concert with the signalling pathway of mTOR in IL2-dependent phos-phorylation of ribosomal protein S6. The phosphorylation and activity of PKB/Akt in IL2-stimulated CTLL2 cells were rapamycin-insensitive and reduced upon wortmannin treatment of the cells, confirming a requirement for PI-3K for Akt activity. The data support the hypothesis that Akt may act downstream to PI-3K and upstream to mTOR in an IL2-mediated signal transduction pathway that controls phosphorylation of the regulatory protein S6 in CTLL2 cells.
authors.affiliation: Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, 166 37 Prague 6, Czech Republic. tuhack@img.cas.cz
authors.forename: Zdena
authors.initials: Z
authors.lastname: Tuhácková
authors.forename: Eva
authors.initials: E
authors.lastname: Sloncová
authors.forename: Martina
authors.initials: M
authors.lastname: Vojtechová
authors.forename: Vlasta
authors.initials: V
authors.lastname: Sovová
mesh_terms: D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D002460:Cell Line; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D015151:Immunoblotting; D007376:Interleukin-2 / Q000378:metabolism*; D051379:Mice; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000502:physiology*; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D038601:Ribosomal Protein S6 / Q000737:chemistry* / Q000378:metabolism; D015398:Signal Transduction; D020123:Sirolimus / Q000494:pharmacology; D058570:TOR Serine-Threonine Kinases; D000077191:Wortmannin
chemical_list: D000730:Androstadienes; D004791:Enzyme Inhibitors; D007376:Interleukin-2; D019869:Phosphatidylinositol 3-Kinases; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D038601:Ribosomal Protein S6; D020123:Sirolimus; D058570:TOR Serine-Threonine Kinases; D000077191:Wortmannin; C546842:MTOR protein, human; C546843:mTOR protein, mouse; C494918:AKT1 protein, human