• International Journal of Oral Biology
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• 제32권1호
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• pp.1-5
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• 2007

Receptor activator of nuclear factor ${\kappa}B$ ligand (RANKL) induces osteoclast formation from hematopoietic cells via up-regulation of positive regulators, including $NF-{\kappa}B$, c-Fos, microphthalmia transcription factor (Mitf), PU.1, and nuclear factor of activated T cells (NFAT) c1. In addition to the positive regulation by these transcription factors, RANKL appears to regulate negative regulators such as MafB and inhibitors of differentiation (Ids). Ids and MafB are abundantly expressed in osteoclast precursors, bone marrowderived monocyte/macrophage lineage cells (BMMs). Expression levels of these genes are significantly reduced by RANKL during osteoclastogenesis. Overexpression of these genes in BMMs inhibits the formation of tartarate-resistant acid phosphatase (TRAP)-positive multinuclear osteoclasts by down-regulation of NFATc1 and osteoclast-associated receptor (OSCAR), which are important for osteoclast differentiation. Furthermore, reduced expression of these genes enhances osteoclastogenesis and increases expression of NFATc1 and OSCAR. Taken together, RANKL induces osteoclastogenesis via up-regulation of positive regulators as well as down-regulation of negative regulators.

• International Journal of Oral Biology
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• 제38권2호
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• pp.67-72
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• 2013

This study examined the anti-osteoclastogenic effects of baicalin on receptor activator of NF-${\kappa}$B ligand (RANKL)-induced RAW264.7 cells. Baicalin is a flavonoid that is produced by Scutellaria baicalensis and is known to have multiple biological properties, including antibacterial, anti-inflammatory and analgesic effects. The effects of baicalin on osteoclasts were examined by measuring 1) cell viability; 2) the formation of tartrate-resistant acid phosphatase (TRAP) (+) multinucleated cells; 3) RANK/RANKL signaling pathways and 4) mRNA levels of osteoclast-associated genes. Baicalin inhibited the formation of RANKL-stimulated TRAP (+) multinucleated cells and also suppressed the RANKL-stimulated activation of p-38, ERK, cSrc and AKT signaling. Baicalin also inhibited the RANKL-stimulated degradation of $I{\kappa}B$ in RAW264.7 cells. In addition, the RANKL-stimulated induction of NFATc1 transcription factors was found to be abrogated by this flavonoid. Baicalin was further found to decrease the mRNA expression of osteoclast-associated genes, including carbonic anhydrase II, TRAP and cathepsin K in the RAW264.7 cells. Our data thus demonstrate that baicalin inhibits osteoclastogenesis by inhibiting the RANKL-induced activation of signaling molecules and transcription factors in osteoclast precursors.

• 치위생과학회지
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• 제15권6호
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• pp.753-760
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• 2015

숙주 면역 반응과 면역 체계는 치주 질환에 대한 개인의 감수성의 주요 원인이다. 세균 감염과 흡연은 치주 조직의 파괴의 원인과 진행에 관여하는 중요한 환경 위험 요인이다. 따라서, 본 연구는 사람 치주인대세포에서 LPS와 니코틴이 전염증성 사이토카인인 iNOS/COX-2의 발현과 NO/$PGE_2$ 생산에 미치는 영향을 알아보고 NFATc1가 어떤 기전으로 항염작용을 하는지 밝히고자 하였다. LPS와 니코틴을 처리한 사람 치주인대세포에서 iNOS/COX-2의 발현과 함께 NO/$PGE_2$ 생산은 증가되었다. NFATc1 inhibitor인 CsA는 LPS와 니코틴에 의해 유도되는 iNOS/COX-2의 발현과 함께 NO/$PGE_2$ 생산을 감소시켰다. 이러한 연구 결과로 볼 때, NFAT signaling pathway가 LPS와 니코틴에 의한 iNOS/COX-2의 발현을 조절하여 NO/$PGE_2$ 매개 염증에 대해 방어할 수 있다고 생각된다.

• International Journal of Oral Biology
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• 제45권1호
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• pp.15-24
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• 2020

The fruit of Chaenomeles sinensis (Thouin) Koehne (Chaenomelis Fructus) known as "Mo-Gua" in Korea has been commonly used in traditional medicine to treat inflammatory diseases, such as sore throat. However, its effect on bone metabolism has not been elucidated yet. Here, we examined the effect of Chaenomelis Fructus ethanol extract (CF-E) on receptor activator of nuclear factor (NF)-κB ligand (RANKL)-mediated osteoclast differentiation and formation. CF-E considerably inhibited osteoclast differentiation and tartrate-resistant acid phosphatase-positive multinuclear cell formation from bone marrow-derived macrophages and osteoclast precursor cells in a dose-dependent manner. In addition, the formation of actin rings and resorption pits were significantly suppressed in CF-E-treated osteoclasts as compared with the findings in non-treated control cells. Consistent with these phenotypic inhibitory results, the expressions of osteoclast differentiation marker genes (Acp5, Atp6v0d2, Oscar, CtsK, and Tm7sf4) and Nfatc1, a pivotal transcription factor for osteoclastogenesis, were markedly decreased by CF-E treatment. The inhibitory effect of CF-E on RANKL-induced osteoclastogenesis was associated with the suppression of NFATc1 expression, not by regulation of mitogen-activated protein kinases and NF-κB activation but by the inactivation of phospholipase C gamma 1 and 2. These results indicate that CF-E has an inhibitory effect on osteoclast differentiation and formation, and they suggest the possibility of CF-E as a traditional therapeutic agent against bone-resorptive diseases, such as osteoporosis, rheumatoid arthritis, and periodontitis.

• BMB Reports
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• 제45권3호
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• pp.171-176
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• 2012

Receptor activator of NF-${\kappa}B$ ligand (RANKL) triggers the differentiation of bone marrow-derived monocyte/macrophage precursor cells (BMMs) of hematopoietic origin into osteoclasts through the activation of mitogen-activated protein (MAP) kinases and transcription factors. Recently, reactive oxygen species (ROS) and antioxidant enzymes were shown to be closely associated with RANKL-mediated osteoclast differentiation. Although glutaredoxin2 (Glrx2) plays a role in cellular redox homeostasis, its role in RANKL-mediated osteoclastogenesis is unclear. We found that Glrx2 isoform b (Glrx2b) expression is induced during RANKLmediated osteoclastogenesis. Over-expression of Glrx2b strongly enhanced RANKL- mediated osteoclastogenesis. In addition, Glrx2b-transduced BMMs enhanced the expression of key transcription factors c-Fos and NFATc1, but pre-treatment with SB203580, a p38-specific inhibitor, completely blocked this enhancement. Conversely, down-regulation of Glrx2b decreased RANKL- mediated osteoclastogenesis and the expression of c-Fos and NFATc1 proteins. Also, Glrx2b down-regulation attenuated the RANKL-induced activation of p38. Taken together, these results suggest that Glrx2b enhances RANKL-induced osteoclastogenesis via p38 activation.

• Molecules and Cells
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• 제40권10호
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• pp.706-713
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• 2017

Osteoclasts are bone-resorbing cells that are derived from hematopoietic precursor cells and require macrophage-colony stimulating factor and receptor activator of nuclear factor-${\kappa}B$ ligand (RANKL) for their survival, proliferation, differentiation, and activation. The binding of RANKL to its receptor RANK triggers osteoclast precursors to differentiate into osteoclasts. This process depends on RANKL-RANK signaling, which is temporally regulated by various adaptor proteins and kinases. Here we summarize the current understanding of the mechanisms that regulate RANK signaling during osteoclastogenesis. In the early stage, RANK signaling is mediated by recruiting adaptor molecules such as tumor necrosis factor receptorassociated factor 6 (TRAF6), which leads to the activation of mitogen-activated protein kinases (MAPKs), and the transcription factors nuclear factor-${\kappa}B$ (NF-${\kappa}B$) and activator protein-1 (AP-1). Activated NF-${\kappa}B$ induces the nuclear factor of activated T-cells cytoplasmic 1 (NFATc1), which is the key osteoclastogenesis regulator. In the intermediate stage of signaling, the co-stimulatory signal induces $Ca^{2+}$ oscillation via activated phospholipase $C{\gamma}2$ ($PLC{\gamma}2$) together with c-Fos/AP-1, wherein $Ca^{2+}$ signaling facilitates the robust production of NFATc1. In the late stage of osteoclastogenesis, NFATc1 translocates into the nucleus where it induces numerous osteoclast-specific target genes that are responsible for cell fusion and function.

• 대한의생명과학회지
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• 제23권4호
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• pp.295-302
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• 2017

Mononuclear osteoclast precursors derived from hematopoietic progenitors fuse together and then become multinucleated mature osteoclasts by macrophage-colony stimulating factor (M-CSF) and receptor activator of nuclear factor-${\kappa}B$ ligand (RANKL). Especially, the binding of RANKL to its receptor RANK provides key signals for osteoclast differentiation and bone-resorbing function. RANK transduces intracellular signals by recruiting adaptor molecules such as TNFR-associated factors (TRAFs), which then activate mitogen activated protein kinases (MAPKs), Src/PI3K/Akt pathway, nuclear factor-${\kappa}B$ (NF-${\kappa}B$) and finally amplify NFATc1 activation for the transcription and activation of osteoclast marker genes. This review will briefly describe RANKL-RANK signaling pathways and key molecules critical for osteoclast differentiation.

• 농업생명과학연구
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• 제50권2호
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• pp.151-160
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• 2016

염증성 사이토카인은 파골세포형성과정에서 중요한 요인이며, 뼈의 흡수는 자주 골다공증과 연결된다. 설포라판은 보로콜리의 화뢰로 부터 분리된 물질로 염증성 사이토카인을 억제한다고 알려져 있다. 본 실험에서는 Receptor activator of nuclear factor kappaB ligand(RANKL)로 자극된 세포에서 설포라판이 파골세포 형성 억제에 대한 효과를 측정하였다. 설포라판은 대식세포인 RAW 264.7 세포에서 파골세포 특이 마커 유전자인 tartrate-resistant acid phosphatase(TRAP), Cathepsin K, matrix metalloproteinase 9(MMP-9), calcitonin receptor을 저해하였으며, TRAP, MMP-9, tumor necrosis factor receptor-associated factor 6(TRAF6)와 전사인자인 nuclease factor of activated T cells(NFATc1)의 단백질 발현과 RANKL로 자극하였을 때 전자인사인 nuclear factor kappaB(NF-kappaB)의 전사활성도 억제 하였다. 이와 같은 결과로 설포라판이 NF-kappaB의 전사활성 억제뿐만 아니라, 파골세포형성인자(TRAP, cathepsin K, MMP-9, calcitonin, NFATc1)와 NFATc1의 발현을 억제시키는 효과가 있음을 확인하였다.

• Biomolecules & Therapeutics
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• 제32권2호
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• pp.205-213
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• 2024

Hydroxychavicol, a primary active phenolic compound of betel leaves, previously inhibited bone loss in vivo by stimulating osteogenesis. However, the effect of hydroxychavicol on bone remodeling induced by osteoclasts is unknown. In this study, the anti-osteoclastogenic effects of hydroxychavicol and its mechanism were investigated in receptor activator of nuclear factor kappa-B ligand (RANKL)-induced osteoclasts. Hydroxychavicol reduced the number of tartrate resistance acid phosphatase (TRAP)-positive multinucleated, F-actin ring formation and bone-resorbing activity of osteoclasts differentiated from RAW264.7 cells in a concentration-dependent manner. Furthermore, hydroxychavicol decreased the expression of osteoclast-specific genes, including cathepsin K, MMP-9, and dendritic cell-specific transmembrane protein (DC-STAMP). For mechanistic studies, hydroxychavicol suppressed RANKL-induced expression of major transcription factors, including the nuclear factor of activated T-cells 1 (NFATc1), c-Fos, and c-Jun. At the early stage of osteoclast differentiation, hydroxychavicol blocked the phosphorylation of NF-κB subunits (p65 and Iκβα). This blockade led to the decrease of nuclear translocation of p65 induced by RANKL. In addition, the anti-osteoclastogenic effect of hydroxychavicol was confirmed by the inhibition of TRAP-positive multinucleated differentiation from human peripheral mononuclear cells (PBMCs). In conclusion, hydroxychavicol inhibits osteoclastogenesis by abrogating RANKL-induced NFATc1 expression by suppressing the NF-κB signaling pathway in vitro.

• 대한본초학회지
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• 제38권5호
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• pp.9-19
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• 2023

Objectives : Osteoporosis is a systemic skeletal disorder characterized by reduced bone mineral density and increased risk of fractures. Bisphosphonates and selective estrogen receptors, which are bone resorption inhibitors that are currently widely used as osteoporosis treatments, show serious side effects when administered for a long time. Research on bone resorption inhibitors that complement the problems of existing treatments is needed. The purpose of this study was to investigate the effect of inhibiting osteoclast differentiation and activity on the tuberous root of Ampelopsis japonica (Thunb.) Makino (AM). Methods : After extracting AM using distilled water and ethanol, the inhibitory effects of the two solvents on osteoclast differentiation were compared using the RANKL-induced in vitro experimental model and the TRAP assay kit. The impact of AM on bone resorption was investigated through the pit formation assay, and its effect on F-actin formation was assessed through fluorescent staining. Additionally, protein and mRNA expression levels of osteoclast differentiation markers (NFATc1, c-Fos, TRAP and ATP6v0d2) and resorption markers (MMP-9, CTK, and CA2) were analyzed via western blot and RT-PCR. Results : AM treatment significantly decreased the number of TRAP-positive cells and pit formation area. Furthermore, AM suppressed both the protein and mRNA expression of NFATc1 and c-Fos, key transcription factors involved in osteoclast differentiation and it downregulated the expression of osteoclast-associated genes such as TRAP, CTK, MMP-9, CA2, and ATP6v0d2. Conclusions : These results suggest that AM can inhibit bone resorption and osteoclast differentiation, indicating its potential for use in the treatment and prevention of osteoporosis.