title: Fisetin antagonizes cell fusion, cytoskeletal organization and bone resorption in RANKL-differentiated murine macrophages.
abstract: Osteoclastogenesis is comprised of several stage s including progenitor survival, differentiation to mononuclear preosteoclasts, cell fusion to multinuclear mature osteoclasts, and activation to osteoclasts with bone resorbing activity. Botanical antioxidants are now being increasingly investigated for their health-promoting effects on bone. This study investigated that fisetin, a flavonol found naturally in many fruits and vegetables, suppressed osteoclastogenesis by disturbing receptor activator of nuclear factor (NF)-κB ligand (RANKL)-mediated signaling pathway and demoting osteoclastogenic protein induction. Nontoxic fisetin at ≤10 μM inhibited the induction of RANK, tumor necrosis factor receptor associated factor 6 (TRAF6) and the activation of NF-κB in RANKL-stimulated RAW 264.7 macrophages. In RANKL-differentiated osteoclasts cell fusion protein of E-cadherin was induced, which was dampened by fisetin. The formation of tartrate-resistance acid phosphatase-positive multinucleated osteoclasts was suppressed by adding fisetin to RANKL-exposed macrophages. It was also found that fisetin reduced actin ring formation and gelsolin induction of osteclasts enhanced by RANKL through disturbing c-Src-proline-rich tyrosine kinase 2 signaling. Fisetin deterred preosteoclasts from the cell-cell fusion and the organization of the cytoskeleton to seal the resorbing area and to secret protons for bone resorption. Consistently, the 5 day-treatment of fisetin diminished RANKL-induced cellular expression of carbonic anhydrase II and integrin β3 concurrently with a reduction of osteoclast bone-resorbing activity. Therefore, fisetin was a natural therapeutic agent retarding osteoclast fusion and cytoskeletal organization such as actin rings and ruffled boarder, which is a property of mature osteoclasts and is required for osteoclasts to resorb bone.
authors: Department of Food Science and Nutrition, Hallym University, Chuncheon, South Korea.
authors: Yun-Ho
authors: YH
authors: Kim
authors: Department of Food Science and Nutrition, Hallym University, Chuncheon, South Korea.
authors: Jung-Lye
authors: JL
authors: Kim
authors: Department of Food Science and Nutrition, Hallym University, Chuncheon, South Korea.
authors: Eun-Jung
authors: EJ
authors: Lee
authors: Department of Food Science and Nutrition, Hallym University, Chuncheon, South Korea.
authors: Sin-Hye
authors: SH
authors: Park
authors: Department of Food Science and Nutrition, Hallym University, Chuncheon, South Korea.
authors: Seon-Young
authors: SY
authors: Han
authors: Department of Conversing Technology and Graduated School of Venture, School of Industrial Biotechnology, Hoseo University, Seoul, South Korea.
authors: Soon Ah
authors: SA
authors: Kang
authors: Department of Food Science and Nutrition, Hallym University, Chuncheon, South Korea. Electronic address: yhkang@hallym.ac.kr.
authors: Young-Hee
authors: YH
authors: Kang
mesh_terms: D000818:Animals; D001862:Bone Resorption; D002454:Cell Differentiation / Q000502:physiology*; D002459:Cell Fusion; D003599:Cytoskeleton / Q000187:drug effects*; D005419:Flavonoids / Q000494:pharmacology*; D044948:Flavonols; D008264:Macrophages / Q000166:cytology*; D051379:Mice; D053245:RANK Ligand / Q000502:physiology*
chemical_list: D005419:Flavonoids; D044948:Flavonols; D053245:RANK Ligand; C505689:Tnfsf11 protein, mouse; C017875:fisetin
keywords: Bone resorption; Cell fusion; Cytoskeletal organization; Fisetin; Pyk; c-Src