title: Differential effects of Akt pathway inhibitors on IL-1β-induced protein phosphorylation in human fibroblast-like synoviocytes.
abstract: BACKGROUND
  Interleukin (IL)-1β activates various signal transduction pathways including p38 mitogen-activated protein kinase (MAPK), c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK), and Akt in human fibroblast-like synoviocytes (HFLS).
  
  
  OBJECTIVE
  We investigated the effects of an Akt inhibitor, a phosphatidylinositol 3-kinase (PI3K) inhibitor, and Akt RNAi knockdown on IL-1β-induced protein phosphorylation in HFLS to clarify the role of the PI3K/Akt signaling pathway in the phosphorylation of the inhibitor of κB (IκB)α and heat shock protein 27 (HSP27).
  
  
  METHODS
  A multiplex suspension array system was used for the detection of phosphorylated proteins.
  
  
  RESULTS
  IL-1β induced biphasic phosphorylation of IκBα, with the first phase occurring 10 min after IL-1β stimulation, and this was augmented by treatment with Akt inhibitor IV. However, this phenomenon was not observed after treatment with LY-294002, a PI3K inhibitor. Furthermore, Akt inhibitor IV suppressed ERK2 phosphorylation, whereas LY-294002 and Akt RNAi had no effect. In contrast, Akt inhibitor IV, LY-294002, and Akt RNAi augmented HSP27 phosphorylation.
  
  
  CONCLUSIONS
  Modulation of different stages of the PI3K/Akt pathway may differentially affect the phosphorylation of IκBα and HSP27 in HFLS.
authors.affiliation: Research and Development Center, Santen Pharmaceutical Co., Ltd., Takayama-cho, Ikoma, Nara, Japan. ftsuji@minuet.plala.or.jp
authors.forename: Fumio
authors.initials: F
authors.lastname: Tsuji
authors.forename: Kentaro
authors.initials: K
authors.lastname: Oh-Hashi
authors.forename: Kazutoshi
authors.initials: K
authors.lastname: Kiuchi
mesh_terms: D002478:Cells, Cultured; D002867:Chromones / Q000494:pharmacology; D005347:Fibroblasts; D055785:Gene Knockdown Techniques; D055551:HSP27 Heat-Shock Proteins / Q000378:metabolism*; D006801:Humans; D020672:I-kappa B Proteins / Q000378:metabolism*; D053583:Interleukin-1beta / Q000378:metabolism*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D009025:Morpholines / Q000494:pharmacology; D000072000:NF-KappaB Inhibitor alpha; D051058:Oncogene Protein v-akt / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism*; D058539:Phosphatidylinositol 3-Kinase / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D034622:RNA Interference; D013583:Synovial Membrane / Q000166:cytology* / Q000378:metabolism*
chemical_list: D002867:Chromones; D055551:HSP27 Heat-Shock Proteins; D020672:I-kappa B Proteins; D053583:Interleukin-1beta; D009025:Morpholines; C000606204:NFKBIA protein, human; D000081082:Phosphoinositide-3 Kinase Inhibitors; D000072000:NF-KappaB Inhibitor alpha; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D058539:Phosphatidylinositol 3-Kinase; D051058:Oncogene Protein v-akt; C535150:MAPK1 protein, human; D019950:Mitogen-Activated Protein Kinase 1