RANKL-induced osteoclastogenesis is suppressed by 4-O-methylhonokiol in bone marrow-derived macrophages

Abstract

Magnolol, honokiol, and obovatol are well known bioactive constituents of the bark of Magnolia officinalis and have been reported to have beneficial effects in various diseases. We recently isolated a novel active compound, 4-O-methylhonokiol (4-O-MH) from the ethanol extract of M. officinalis, which was previously reported to have pharmacological effects including anti-inflammatory, anti-oxidative, and anti-aging activities. Here, we examined the pharmacological properties of 4-O-MH on osteoblast (bone-forming cells) and osteoclast (bone-resorbing cells) differentiation, and its underlying signaling pathways in primary cultured pre-osteoblasts and bone marrow macrophages. Our results showed that 4-O-MH did not affect cell viability in pre-osteoblasts and did not influence osteoblast differentiation and mineralized nodule formation, as assessed by alkaline phosphatase activity and Alizarin red staining. However, 4-O-MH significantly inhibited TRAP-positive multinuclear osteoclasts and F-actin ring formation during Receptor activator of NF-κB ligand (RANKL)-mediated osteoclastogenesis without cytotoxicity. In addition, 4-O-MH suppressed RANKL-induced critical factors (c-Fos, NF-ATc1, TRAP, and ITB3) for osteoclast differentiation and function. Furthermore, RANKL-mediated signaling, including ERK1/2, AKT, and NF-kB pathways was attenuated by 4-O-MH. Taken together, 4-O-MH has an inhibitory role in RANKL-mediated osteoclastogenesis but not osteoblast differentiation, and our findings also suggest that 4-O-MH is a potential therapeutic agent for bone-destructive diseases such as osteoporosis, alveolar bone resorption, and osteoarthritis.

Chitinase 3 like 1 suppresses the stability and activity of p53 to promote lung tumorigenesis

“…Cell proliferation was measured by an 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay to detect NADH-dependent dehydrogenase activity as previously described [37]. 5 mg/ml 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT; Sigma-Aldrich, St. Louis, MO) diluted in PBS was added to the cells, which was then incubated for 2 h to allow MTT to metabolize to formazan.…”

Limonoid Triterpene, Obacunone Increases Runt-Related Transcription Factor 2 to Promote Osteoblast Differentiation and Function

“…Osteoblasts actively participate in the bone formation and repair by complex events: the migration and proliferation of pre-osteoblasts, osteoblast differentiation, and then the synthesis, secretion, and mineralization of the bone matrix [10]. Dysregulation in complex processes causes pathogenesis in bone diseases such as osteoporosis and periodontal disease [43][44][45][46]. Thus, our findings suggest that Obac might be a phytotherapeutic compound for drug development based on biological mechanisms to treat bone diseases such as osteoporosis and periodontal disease.…”

Magnolol prevents ovariectomy‑induced bone loss by suppressing osteoclastogenesis via inhibition of the nuclear factor‑κB and mitogen‑activated protein kinase pathways

“…RANKL serves a vital role in osteoclast maturation (32). RANKL binds to RANK on immature osteoclasts, resulting in the activation of the NF-κB and MAPK pathways (11,12,20). The NF-κB pathway is closely associated with osteoclastogen-esis and inflammation, and agents targeting this pathway are used to treat osteoporosis and inflammatory conditions (13,28).…”

“…Magnolol is the active component of the Chinese medicine Magnolia officinalis and is used clinically for its anti-inflammatory and antioxidant effects (16-19). Magnolol reportedly inhibits RANKL-induced osteoclastic differentiation of RAW264.7 macrophages (20). However, further research is required to assess the effect of magnolol on osteoporosis and the underlying mechanism(s).…”