• Archives of Pharmacal Research
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• v.26 no.11
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• pp.937-942
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• 2003

Nitric oxide(NO) induces apoptosis in human osteoblasts. Treatment with exogenous NO donors, SNAP (S-Nitroso-N-acelylpenicillamine) and SNP (sodium nitroprusside), to MG-63 osteoblasts resulted in apoptotic morphological changes, as shown by a bright blue-fluorescent condensed nuclei and chromatin fragmentation by fluorescence microscope of Hoechst 33258-staining. The activities of caspase-9 and the subsequent caspase-3-like cysteine proteases were increased during NO-induced cell death. Pretreatment with Z-VAD-FMK (a pancaspase inhibitor) or Ac-DEVD-CHO (a specific caspase-3 inhibitor) abrogated the NO-induced cell death. The NO donor markedly activated JNK, a stress-activated protein kinase in the human osteoblasts. This study showed that the inhibition of the JNK pathway markedly reduced NO-induced cell death. But neither PD98059 (MEK inhibitor) nor SB203580 (p38 MAPK inhibitor) had any effect on NO-induced death. Taken together, these results suggest that JNK/SAPK may be related to NO-induced apoptosis in MG-63 human osteoblasts.

• BMB Reports
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• v.43 no.9
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• pp.579-583
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• 2010

The adipocyte-derived hormone leptin regulates appetite and bone mass. Recent research demonstrates that reciprocally, osteoblasts have a role in controlling energy metabolism. Several genes expressed in osteoblasts are involved in this process, and one of them is the Esp gene. The remaining genes regulate Esp gene expression. OST-PTP, the protein name of Esp, regulates the carboxylation of osteocalcin secreted from osteoblasts, thus affecting insulin sensitivity and insulin secretion. This review provides evidence for a novel interpretation of the connection between bone and energy metabolism and expands our understanding of the novel physiology of bone beyond its classical functions.

• Journal of Periodontal and Implant Science
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• v.37 no.3
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• pp.553-562
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• 2007

Osteoblasts regulate osteoclastogenesis by production of various cytokines. Aggregatibacter(A) ac-tinomycetemcomitans is one of periodontopathogens which invades gingival tissue. Therefore, clarifying the effect of alive A. actinomycetemcomitans on osteoblasts is important to understand the mechanism of alveolar bone resorption in periodontitis. We investigated induction of osteoclastogenesis-inducing cytokines, adherence, and invasion by A. actinomycetemcomitans in osteoblasts. Osteoblasts were isolated from mouse calvaria and expression of cytokines was determined by RT-PCR. When the ratio of the number of A. actinomycetemcomtians to the number of osteoblasts was 10:1, 50:1 and 100:1, RANKL mRNA expression was increased. A. actinomycetemcomitans also increased expression of macrophage inflammatory protein (MIP) -1${\alpha}$, interleukin (IL)-1${\beta}$, and tumor necrosis factor (TNF)-${\alpha}$. A. actinomycetemcomitans attached to and invaded osteoblasts at ratio of 1000:1. These results suggest that A. actinomycetemcomitans increases osteoclastogenesis-inducing ability of osteoblasts by stimulating the expression of RANKL, MIP-1${\alpha}$,IL-1${\beta}$, and TNF-${\alpha}$ and that invasion of A. actinomycetemcomitans provides a means by which the bacteria escape from immune system and antibiotic therapy.

• Journal of dental hygiene science
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• v.18 no.2
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• pp.130-135
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• 2018

The aim of this study was to investigate the role of osteal macrophages (osteomac) and osteocytes in bone remodeling using a mathematical model. We constructed the bone system with pre-osteoblasts, osteoclasts, osteocytes, and osteomac. Each link of the parameters and ordinary differential equations followed the Graham's model in 2013 except for the parameters of osteomac signaling and osteocytes signaling to link preosteoblasts and osteoblasts. We simulated the changes in each cell and bone volume according to the changes in the parameters of osteomac signaling and osteocytes signaling. The results showed bone volume was unstable and decreased gradually when the effectiveness of osteocytes and osteomac dropped below a certain level. When the parameters of osteomac signaling and osteocytes signaling to link preosteoblasts and osteoblasts had a value less than 1, bone volume increased with the increase in the parameter of osteomac signaling to link preosteoblasts and osteoblasts. Moreover, although the parameter of osteocytes signaling to link preosteoblasts and osteoblasts, increased in case of a small parameter of osteomac signaling, bone volulme decreased. If the parameters of osteomac signaling to link preosteoblasts and osteoblasts were over a certain level, bone volume was positively maintained, despite the parameter of osteocyte signaling to link preosteoblasts and osteoblasts. We suggested the osteomac may affect bone remodeling and may play an important role in bone cell network.

• Archives of Pharmacal Research
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• v.27 no.12
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• pp.1258-1262
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• 2004

Phosphodiesterase (PDE) 4 is an enzyme that degrades intracellular cAMP. In the present study, the effect of rolipram, a specific phosphodiesterase (PDE) 4 inhibitor, on osteoclast formation was investigated. Rolipram induced osteoclast formation in cocultures of mouse bone marrow cells and calvarial osteoblasts. This activity was not observed in the absence of calvarial osteoblasts, suggesting that calvarial osteoblasts are likely target cells of rolipram. Osteoclast formation by rolipram was completely blocked by the addition of osteoprotegerin (OPG), a soluble decoy receptor for the osteoclast differentiation factor, TNF-related activation-induced cytokine (TRANCE, identical to RANKL, ODF, and OPGL). Northern blot analysis revealed the effect of rolipram to be associated with the increased expression of TRANCE mRNA in mouse calvarial osteoblasts. Collectively, these data indicate that PDE4 inhibitor up-regulates the TRANCE mRNA expression in osteoblasts, which in turn controls osteoclast formation.

• YAKHAK HOEJI
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• v.49 no.1
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• pp.109-113
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• 2005

In the present study treatment of IBMX, a phosphodiesterase (PDE) inhibitor, alone induced osteoclast formation in co-cultures of mouse bone marrow cells and calvarial osteoblasts. However, treatment of IBMX in combination with prostaglandin $E_2\;(PGE_2)$ inhibited osteoclast formation in a dose-dependent manner. Among various isozyme-specific PDE inhibitors, a PDE4 specific inhibitor, rolipram, showed similar effects as IBMX on osteoclast formation. To address the involvement of cyclic adenosine monophosphate (cAMP) in osteoclast formation, cAMP concentration in calvarial osteoblasts was investigated. When calvarial osteoblasts were co-cultured with IBMX alone or in combination with $PGE_2$, the patterns of cAMP concentration in calvarial osteoblasts were differ each other suggesting that cAMP in calvarial osteoblasts subtly regulates osteoclast formation.

• YAKHAK HOEJI
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• v.54 no.5
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• pp.410-415
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• 2010

We explored the role of phosphodiesterase 4 (PDE4) on parathyroid (PTH)-induced signaling in osteoblasts. PTH was shown to increase the activity of PDE, mainly PDE4, in osteoblasts, which is partly attributable to elevated PDE4B and PDE4D mRNA expression. The use of PDE4 inhibitor strengthened the PTH-induced extracellular signal-regulated kinase (ERK) and p38 MAP kinase (MAPK) activation. Furthermore, the PDE4 inhibitor stimulated PTH-induced receptor activator of nuclear factor-${\kappa}B$ ligand (RANKL) expression in osteoblasts, which in turn increased osteoclast formation. Taken together, these data suggest the negative role of PDE4 on PTH-induced signaling in osteoblasts.

• YAKHAK HOEJI
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• v.51 no.4
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• pp.235-238
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• 2007

To determine the regulatory roles of phosphodiesterase (PDE) inhibitors on $PGE_2$-induced osteoclastogenesis, we investigated the effect of PDE inhibitors on osteoclast formation in the presence of $PGE_2$. Among PDE isozyme specific inhibitors, milrinone, a selective PDE3 inhibitor, and rolipram, a specific PDE4 inhibitor, increased $PGE_2$-induced osteoclast formation in cocultures of mouse bone marrow cells and osteoblasts. To verify that whether the PDE3 and PDE4 inhibitors act indirectly on osteoblasts, we measured the concentration of intracellular cAMP in osteoblasts. Treatment of milrinone or rolipram increased $PGE_2$-stimulated cAMP levels in osteoblasts. Furthermore, northern blot analysis revealed that the PDE3 and PDE4 inhibitors works synergistically with $PGE_2$ to increase the expression of TRANCE mRNA in osteoblasts. On the contrary, the PDE3 and PDE4 inhibitors did not augment the number of osteoclasts differentiated from bone marrow cells by $PGE_2$. In conclusion, the stimulation of $PGE_2$-induced osteoclast formation by the PDE3 and PDE4 inhibitors are attributable to their indirect effect on osteoblasts, not to their direct effect on bone marrow-derived osteoclast precursors.

• BMB Reports
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• v.52 no.6
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• pp.391-396
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• 2019

Receptor activator of nuclear factor kappa B ligand (RANKL) expression in osteoblasts is regulated by 1,25-dihydroxyvitamin D3 (1,25D3). CCAAT/enhancer-binding protein beta ($C/EBP{\beta}$) has been proposed to function as a transcription factor and upregulate RANKL expression, but it is still uncertain how $C/EBP{\beta}$ is involved in 1,25D3-induced RANKL expression of osteoblasts. 1,25D3 stimulation increased the expression of RANKL and $C/EBP{\beta}$ genes in osteoblasts and enhanced phosphorylation and stability of these proteins. Moreover, induction of RANKL expression by 1,25D3 in osteoblasts was downregulated upon knockdown of $C/EBP{\beta}$. In contrast, $C/EBP{\beta}$ overexpression directly upregulated RANKL promoter activity and exhibited a synergistic effect on 1,25D3-induced RANKL expression. In particular, 1,25D3 treatment of osteoblasts increased $C/EBP{\beta}$ protein binding to the RANKL promoter. In conclusion, $C/EBP{\beta}$ is required for induction of RANKL by 1,25D3.

• Journal of the Korean institute of surface engineering
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• v.41 no.6
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• pp.264-268
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• 2008

Interaction between human osteoblast and TiN films was conducted in vitro. TiN films were produced by cathodic arc plasma deposition. The surface was characterized by atomic force microscopy (AFM). TiN films, glass substrates and Ti films were cultured with human osteoblasts for 48 and 72 h hours. Actin stress fiber patterns and microtubules of osteoblasts were found slightly more organized and distributed on TiN films compared to those on the Ti films and the glass substrates. Human osteoblasts also showed slightly higher cell attachment, proliferation, and focal contact adhesion on TiN films compared to those on Ti films and glass substrates. Our results demonstrated that TiN films showed slightly better cellular adhesion of osteoblasts than Ti films and glass substrates in a short-time culture period.