2-Methoxystypandrone represses RANKL-mediated osteoclastogenesis by down-regulating formation of TRAF6-TAK1 signalling complexes.

Abstract

BACKGROUND AND PURPOSE:

2-Methoxystypandrone (2-MS) is a naphthoquinone isolated from Polygonum cuspidatum, a Chinese herb used to treat bone diseases. Here we have determined whether 2-MS antagonised osteoclast development and bone resorption.

EXPERIMENTAL APPROACH:

RAW264.7 cells were treated with receptor activator of nuclear factor kappaB (NF-kappaB) ligand (RANKL) to induce differentiation into osteoclasts. RT-PCR and Western blot were used to analyse osteoclast-associated gene expression and signalling pathways.

KEY RESULTS:

The number of multinuclear osteoclasts, actin rings and resorption pit formation were markedly inhibited by 2-MS, targeting osteoclast differentiation at an early stage and without significant cytotoxicity. The anti-resorption effect of 2-MS was accompanied by decreasing dendritic cell-specific transmembrane protein and matrix metalloproteinase-9 (MMP-9) mRNA expression. RANKL-increased MMP-9 gelatinolytic activity was also attenuated by concurrent, but not by subsequent addition of 2-MS. 2-MS markedly inhibited not only the RANKL-triggered nuclear translocations of NF-kappaB, c-Fos and nuclear factor of activated T cells c1 (NFATc1), but also the subsequent NFATc1 induction. Degradation of IkappaB and phosphorylation of mitogen-activated protein kinases were also suppressed. RANKL facilitated the formation of signaling complexes of tumour necrosis factor receptor-associated factor 6 and transforming growth factor beta-activated kinase 1 (TRAF6-TAK1), important for osteoclastogenesis and formation of such signalling complexes was prevented by 2-MS.

CONCLUSIONS AND IMPLICATIONS:

The anti-osteoclastogenic effects of 2-MS could reflect the block of RANKL-induced association of TRAF6-TAK1 complexes with consequent decrease of IkappaB-mediated NF-kappaB and mitogen-activated protein kinases-mediated c-Fos activation pathways and suppression of NFATc1 and other gene expression, essential for bone resorption.

• Authors: W F Chiou, J F Liao, C Y Huang, C C Chen
• Journal: British journal of pharmacology (Br J Pharmacol) Vol. 161 Issue 2 Pg. 321-35 (Sep 2010) ISSN: 1476-5381 [Electronic] England
• PMID: 20735418 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• 2-Methoxystypandrone
• Bone Density Conservation Agents
• Drugs, Chinese Herbal
• Naphthoquinones
• Protease Inhibitors
• RANK Ligand
• TNF Receptor-Associated Factor 6
• Mitogen-Activated Protein Kinases
• MAP Kinase Kinase Kinases
• MAP kinase kinase kinase 7

Topics

• Animals
• Bone Density Conservation Agents (isolation & purification, pharmacology)
• Bone Resorption (genetics, metabolism, prevention & control)
• Cell Differentiation (drug effects)
• Cell Line
• Down-Regulation
• Drugs, Chinese Herbal (isolation & purification, pharmacology)
• Fallopia japonica (chemistry)
• MAP Kinase Kinase Kinases (genetics, metabolism)
• Macrophages (cytology, drug effects, metabolism)
• Mice
• Mitogen-Activated Protein Kinases (antagonists & inhibitors)
• Naphthoquinones (isolation & purification, pharmacology)
• Osteoclasts (cytology, drug effects, metabolism)
• Protease Inhibitors (pharmacology)
• Protein Binding
• RANK Ligand (pharmacology)
• Signal Transduction (drug effects)
• TNF Receptor-Associated Factor 6 (genetics, metabolism)