title: AMP-activated protein kinase regulates PDGF-BB-stimulated interleukin-6 synthesis in osteoblasts: involvement of mitogen-activated protein kinases.
abstract: OBJECTIVE
  We have previously reported that platelet-derived growth factor (PDGF)-BB stimulates synthesis of interleukin-6 (IL-6), a potent bone resorptive agent, in osteoblast-like MC3T3-E1 cells, and that the activation of p44/p42 mitogen-activated protein (MAP) kinase, p38MAP kinase and stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK) is implicated in the IL-6 synthesis. In the present study,we investigated the involvement of AMP-activated protein kinase (AMPK), a regulator of energy metabolism, in the PDGF-BB-stimulated IL-6 synthesis in MC3T3-E1 cells.
  
  
  METHODS
  The levels of IL-6 were measured by ELISA. The phosphorylation of each protein kinases was analyzed by Western blotting. The mRNA levels of IL-6 were determined by real-time RT-PCR.
  
  
  RESULTS
  PDGF-BB time-dependently induced the phosphorylation of AMPK. Compound C, an inhibitor of AMPK, which reduced PDGF-BB-induced acetyl-CoA carboxylase phosphorylation, dose-dependently suppressed the PDGF-BB-stimulated IL-6 release. In addition, the PDGF-BB-stimulated IL-6 release in human osteoblasts was also inhibited by compound C. The mRNA expression of IL-6 induced by PDGF-BB was markedly reduced by compound C. The PDGF-BB-induced phosphorylation of p44/p42 MAP kinase, p38 MAP kinase and SAPK/JNK was inhibited by compound C.
  
  
  CONCLUSIONS
  These results strongly suggest that AMPK positively regulates PDGF-BB-stimulated IL-6 synthesis via the MAP kinases in osteoblasts.
authors.affiliation: Department of Orthopedic Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya 467-8601, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Kato
authors.forename: Takanobu
authors.initials: T
authors.lastname: Otsuka
authors.forename: Akira
authors.initials: A
authors.lastname: Kondo
authors.forename: Rie
authors.initials: R
authors.lastname: Matsushima-Nishiwaki
authors.forename: Hideo
authors.initials: H
authors.lastname: Natsume
authors.forename: Osamu
authors.initials: O
authors.lastname: Kozawa
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Tokuda
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*; D000818:Animals; D000077214:Becaplermin; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D015850:Interleukin-6 / Q000096:biosynthesis*; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*; D010006:Osteoblasts / Q000187:drug effects / Q000378:metabolism*; D020574:Proto-Oncogene Proteins c-sis / Q000494:pharmacology*; D011720:Pyrazoles / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology
chemical_list: D015850:Interleukin-6; D020574:Proto-Oncogene Proteins c-sis; D011720:Pyrazoles; D011743:Pyrimidines; C516138:dorsomorphin; D000077214:Becaplermin; D020928:Mitogen-Activated Protein Kinases; D055372:AMP-Activated Protein Kinases