title: L-type Ca(2+) channel agonist inhibits RANKL-induced osteoclast formation via NFATc1 down-regulation.
abstract: OBJECTIVE
  BayK 8644 is an L-type Ca(2+) channel agonist that enhances Ca(2+) influx and elevates cytosolic Ca(2+). As intracellular calcium plays a key role in osteoclast formation, we investigated the effects of BayK 8644 in cultures of bone marrow-derived precursor cells with macrophage colony-stimulating factor (M-CSF) and receptor activator of nuclear factor kappaB ligand (RANKL).
  
  
  METHODS
  We performed an osteoclast formation assay, a pit formation assay, real-time PCR, and Western blot analysis.
  
  
  RESULTS
  BayK 8644 concentration-dependently suppressed osteoclastogenesis, as well as the expression of osteoclastic marker genes. It also decreased osteoclastic bone resorption on a dentine slice. While the RANKL-stimulated induction of IL-1β and IL-6 was not affected, TNF-α induction was reduced by BayK 8644 treatment. In addition, BayK 8644 blocked IκB degradation and the induction of nuclear factor of activated T cells c1 (NFATc1), the master regulator of osteoclast differentiation, following RANKL stimulation. Finally, forced expression of NFATc1 reversed the inhibitory effect of BayK 8644 on osteoclastogenesis, suggesting that NFATc1 is a downstream target for the anti-osteoclastogenic action of BayK 8644. Taken together, our data suggest that BayK 8644 has an anti-osteoclastogenic effect by inhibiting RANKL-induced activation of NF-κB pathways, thereby suppressing the gene expression of NFATc1 in osteoclast precursors.
  
  
  CONCLUSIONS
  Our results provide a molecular understanding of the inhibitory effect of the L-type Ca(2+) channel agonist, BayK 8644, on osteoclastogenesis.
authors.affiliation: College of Pharmacy, Sookmyung Women's University; Hyochangwongil, Yongsan-ku, Seoul, Republic of Korea.
authors.forename: A Long Sae Mi
authors.initials: AL
authors.lastname: Noh
authors.forename: Hyojung
authors.initials: H
authors.lastname: Park
authors.forename: Ting
authors.initials: T
authors.lastname: Zheng
authors.forename: Hyun-Il
authors.initials: HI
authors.lastname: Ha
authors.forename: Mijung
authors.initials: M
authors.lastname: Yim
mesh_terms: D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000818:Animals; D001854:Bone Marrow Cells / Q000187:drug effects; D001862:Bone Resorption / Q000139:chemically induced / Q000517:prevention & control; D002120:Calcium Channel Agonists / Q000494:pharmacology*; D020746:Calcium Channels, L-Type / Q000187:drug effects*; D002478:Cells, Cultured; D015536:Down-Regulation / Q000502:physiology; D015870:Gene Expression / Q000187:drug effects; D005822:Genetic Vectors / Q000235:genetics; D006801:Humans; D007202:Indicators and Reagents; D051379:Mice; D008810:Mice, Inbred C57BL; D009000:Monocytes / Q000378:metabolism; D016328:NF-kappa B / Q000502:physiology; D050778:NFATC Transcription Factors / Q000096:biosynthesis* / Q000235:genetics; D010010:Osteoclasts / Q000187:drug effects*; D053245:RANK Ligand / Q000037:antagonists & inhibitors* / Q000494:pharmacology*; D012313:RNA / Q000096:biosynthesis / Q000235:genetics / Q000302:isolation & purification; D012190:Retroviridae / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis
chemical_list: D002120:Calcium Channel Agonists; D020746:Calcium Channels, L-Type; D007202:Indicators and Reagents; D016328:NF-kappa B; D050778:NFATC Transcription Factors; C494005:Nfatc1 protein, mouse; D053245:RANK Ligand; C505689:Tnfsf11 protein, mouse; D014409:Tumor Necrosis Factor-alpha; D012313:RNA; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester