• Journal of Nutrition and Health
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• v.51 no.1
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• pp.23-30
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• 2018

Purpose: Runx2 (runt-related transcription factor 2), a bone-specific transcription factor, is a key regulator of osteoblast differentiation and its expression is induced by the activation of BMP-2 signaling. This study examined whether zinc modulates BMP-2 signaling and therefore stimulates Runx2 and osteoblast differentiation gene expression. Methods: Two osteoblastic MC3T3-E1 cell lines (subclones 4 as a high osteoblast differentiation and subclone 24 as a low osteoblastic differentiation) were cultured in an osteogenic medium (OSM) as the normal control, Zn-($1{\mu}M$ Zn) or Zn+($15{\mu}M$ Zn) for 24 h. The genes and proteins for BMP-2 signaling (BMP-2, Smad-1/p-Smad-1), transcription factors (Runx2, osterix), and osteoblast differentiation marker proteins were assessed. Results: In both cell lines, BMP-2 mRAN and protein expression and extracellular BMP-2 secretion all decreased in Zn-. The expression of Smad-1 (downstream regulator of BMP-2 signaling) and p-Smad-1 (phosphorylated Smad-1) also downregulated in Zn-. Furthermore, the expression of the bone-specific transcription factors, Runx2 and osterix, decreased in Zn-, which might be due to the decreased BMP-2 expression and Smad-1 activation (p-Smad-1) by Zn-, because Runx2 and osterix both are downstream in BMP-2 signaling. Bone marker gene expression, such as alkaline phosphatase (ALP), collagen type I (COLI), osteocalcin, and osteopontin were also downregulated in Zn-. Conclusion: The results suggest that a zinc deficiency in osteoblasts suppresses the BMP-2 signaling pathway via the suppression of Smad-1 activation, and this suppressed BMP-2 signaling can cause poor osteoblast differentiation.

• International Journal of Oral Biology
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• v.34 no.2
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• pp.115-121
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• 2009

Bone morphogenetic protein (BMP) 2 is a potent osteogenic factor. Although both Smad1/5 and mitogenactivated protein kinases (MAPKs) are activated by BMP2, the hierarchical relationship between them is unclear. In this study, we examined if BMP2-stimulated MAPK activation is regulated by Smad1/5 or vice versa. When C2C12 cells were treated with BMP2, the activation of extracellular signal-regulated kinase (ERK), p38 MAPK and c-Jun-N-terminal kinase was evident within 5 min. The knockdown of both Smad1 and Smad5 by small interfering RNA did not affect the activation of these MAPKs. In addition, neither the overexpression of Smad1 nor Smad5 induced ERK activation. When ERK activation was induced by constitutively active MEK1 expression, the protein level and activation of Smad1 increased. Furthermore, the inhibition of constitutively active BMP receptor type IB-induced ERK activation significantly suppressed Smad1 activation. These results indicate that Smad1/5 activation is not necessary for BMP2-induced MAPK activation and also that ERK positively regulates Smad1 activation.

• The Korean Journal of Physiology and Pharmacology
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• v.17 no.5
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• pp.447-453
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• 2013

Osteoblastic activity of nectandrin A was examined in C2C12 cells. Nectandrin A enhances the BMP-induced osteoblastic differentiation and mineralization, manifested by the up-regulation of differentiation markers (alkaline phosphatase and osteogenic genes) and increased calcium contents. In C2C12 cells co-transfected with expression vector encoding Smad4 and Id1-Luc reporter, nectandrin A increased Id1 luciferase activity in a concentration-dependent manner, when compared to that in BMP-2 treated cells, indicating that Smad signaling pathway is associated with nectandrin A-enhanced osteoblastic differentiation in C2C12 cells. In addition, nectandrin A activated p38 mitogen-activated protein kinase (MAPK) in time- and concentration-dependent manners, and phosphorylated form of pSmad1/5/8 and alkaline phosphatase activity were both decreased when the cells were pretreated with SB203580, a p38 MAPK inhibitor, suggesting that p38 MAPK might be an upstream kinase for Smad signaling pathway. Taken together, nectandrin A enhances the BMP-induced osteoblastic differentiation and mineralization of C2C12 cells via activation of p38 MAPK-Smad signaling pathway, and it has a therapeutic potential for osteoporosis by promoting bone formation.

• Journal of Korean Neurosurgical Society
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• v.65 no.2
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• pp.186-195
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• 2022

Objective : To explore the histological feature of the cervical disc degeneration in patients with degenerative ossification (DO) and its potential mechanisms. Methods : A total of 96 surgical segments, from cervical disc degenerative disease patients with surgical treatment, were divided into ossification group (group O, n=46) and non-ossification group (group NO, n=50) based on preoperative radiological exams. Samples of disc tissues and osteophytes were harvested during the decompression operation. The hematoxylin-eosin staining, Masson trichrome staining and Safranin O-fast green staining were used to compare the histological differences between the two groups. And the distribution and content of transforming growth factor (TGF)-β1, p-Smad2 and p-Smad3 between the two groups were compared by a semi-quantitative immunohistochemistry (IHC) method. Results : For all the disc tissues, the content of disc cells and collagen fibers decreased gradually from the outer annulus fibrosus (OAF) to the central nucleus pulposus (NP). Compared with group NO, the number of disc cells in group O increased significantly. But for proteoglycan in the inner annulus fibrosus (IAF) and NP, the content in group O decreased significantly. IHC analysis showed that TGF-β1, p-Smad2, and p-Smad3 were detected in all tissues. For group O, the content of TGF-β1 in the OAF and NP was significantly higher than that in group NO. For p-Smad2 in IAF and p-Smad3 in OAF, the content in group O were significantly higher than group NO. Conclusion : Histologically, cervical disc degeneration in patients with DO is more severe than that without DO. Local higher content of TGF-β1, p-Smad2, and p-Smad3 are involved in the disc degeneration with DO. Further studies with multi-approach analyses are needed to better understand the role of TGF-β/Smads signaling pathway in the disc degeneration with DO.

• Biomedical Science Letters
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• v.19 no.2
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• pp.124-131
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• 2013

Genome-wide association studies (GWAS) have identified a number of common variants associated with serum liver enzyme homeostasis in population. In the previous study, single nucleotide polymorphisms (SNPs) in several genes have been reported to be associated with serum liver enzyme levels in European population. We aimed to confirm whether the genetic variation of SMAD2 (SMAD family member 2) gene influence the serum liver enzyme levels in Korean population. We genotyped variants in or near SMAD2 in a population-based sample including 994 unrelated Korean adult. Here, we performed association analysis to elucidate the possible relations of genetic polymorphisms in SMAD2 gene with serum liver enzyme levels. By examining genotype data of a total of 944 subjects in 5 hospital health promotion center, we discovered the SMAD2 gene polymorphisms are associated with serum liver enzyme levels. The common and highest significant polymorphism was rs17736760 (${\beta}$=3.51, P=5.31E-07) with glutamic oxaloacetic transferase (GOT), rs17736760 (${\beta}$=5.99, P=1.25E-05) with glutamic pyruvate transaminase (GPT), and rs17736760 (${\beta}$=15.68, P=9.93E-07) with gamma glutamyl transferase (GGT) in all group. Furthermore, the SNP rs17736760 was consistently associated with GOT (${\beta}$=5.25, P=1.72E-06), GPT (${\beta}$=9.97, P=1.16E-05), GGT (${\beta}$=26.13, P=3.43E-06) in men group. Consequently, we found statistically significant SNP in SMAD2 gene that are associated with serum levels of GOT, GPT, and GGT. In addition, these results suggest that the individuals with the minor alleles of the SNP in the SMAD2 gene may be more elevated serum liver enzyme levels in the Korean population.

• Tuberculosis and Respiratory Diseases
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• v.82 no.1
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• pp.42-52
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• 2019

Background: Transforming growth factor ${\beta}$ (TGF-${\beta}$), retinoic acid (RA), p38 mitogen-activated protein kinase (MAPK), and MEK signaling play critical roles in cell differentiation, proliferation, and apoptosis. We investigated the effect of RA and the role of these signaling molecules on the phosphorylation of Smad2/3 (p-Smad2/3) induced by TGF-${\beta}1$. Methods: A549 epithelial cells and CCD-11Lu fibroblasts were incubated and stimulated with or without all-trans RA (ATRA) and TGF-${\beta}1$ and with MAPK or MEK inhibitors. The levels of p-Smad2/3 were analyzed by western blotting. For animal models, we studied three experimental mouse groups: control, bleomycin, and bleomycin+ATRA group. Changes in histopathology, lung injury score, and levels of TGF-${\beta}1$ and Smad3 were evaluated at 1 and 3 weeks. Results: When A549 cells were pre-stimulated with TGF-${\beta}1$ prior to RA treatment, RA completely inhibited the p-Smad2/3. However, when A549 cells were pre-treated with RA prior to TGF-${\beta}1$ stimulation, RA did not completely suppress the p-Smad2/3. When A549 cells were pre-treated with MAPK inhibitor, TGF-${\beta}1$ failed to phosphorylate Smad2/3. In fibroblasts, p38 MAPK inhibitor suppressed TGF-${\beta}1$-induced p-Smad2. In a bleomycin-induced lung injury mouse model, RA decreased the expression of TGF-${\beta}1$ and Smad3 at 1 and 3 weeks. Conclusion: RA had inhibitory effects on the phosphorylation of Smad induced by TGF-${\beta}1$ in vitro, and RA also decreased the expression of TGF-${\beta}1$ at 1 and 3 weeks in vivo. Furthermore, pre-treatment with a MAPK inhibitor showed a preventative effect on TGF-${\beta}1$/Smad phosphorylation in epithelial cells. As a result, a combination of RA and MAPK inhibitors may suppress the TGF-${\beta}1$-induced lung injury and fibrosis.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.1
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• pp.273-276
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• 2014

Ellagic acid has been shown to inhibit tumor cell growth. However, the underlying molecular mechanisms remain elusive. In this study, our aim was to investigate whether ellagic acid inhibits the proliferation of MCF-7 human breast cancer cells via regulation of the TGF-${\beta}$/Smad3 signaling pathway. MCF-7 breast cancer cells were transfected with pEGFP-C3 or pEGFP-C3/Smad3 plasmids, and treated with ellagic acid alone or in combination with SIS3, a specific inhibitor of Smad3 phosphorylation. Cell proliferation was assessed by MTT assay and the cell cycle was detected by flow cytometry. Moreover, gene expression was detected by RT-PCR, real-time PCR and Western blot analysis. The MTT assay showed that SIS3 attenuated the inhibitory activity of ellagic acid on the proliferation of MCF-7 cells. Flow cytometry revealed that ellagic acid induced G0/G1 cell cycle arrest which was mitigated by SIS3. Moreover, SIS3 reversed the effects of ellagic acid on the expression of downstream targets of the TGF-${\beta}$/Smad3 pathway. In conclusion, ellagic acid leads to decreased phosphorylation of RB proteins mainly through modulation of the TGF-${\beta}$/Smad3 pathway, and thereby inhibits the proliferation of MCF-7 breast cancer cells.

• BMB Reports
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• v.52 no.3
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• pp.202-207
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• 2019

Keloids are the most common pathological form of trauma healing, with features that seriously affect appearance and body function, are difficult to treat and have a high recurrence rate. Emerging evidence suggests that miRNAs are involved in a variety of pathological processes and play an important role in the process of fibrosis. In this study, we investigated the function and regulatory network of miR-152-5p in keloids. The miRNA miR-152-5p is frequently downregulated in keloid tissue and primary cells compared to normal skin tissue and fibroblasts. In addition, the downregulation of miR-152-5p is significantly associated with the proliferation, migration and apoptosis of keloid cells. Overexpression of miR-152-5p significantly inhibits the progression of fibrosis in keloids. Smad3 is a direct target of miR-152-5p, and knockdown of Smad3 also inhibits fibrosis progression, consistent with the overexpression of miR-152-5p. The interaction between miR-152-5p and Smad3 occurs through the Erk1/2 and Akt pathways and regulates collagen3 production. In summary, our study demonstrates that miR-152-5p/Smad3 regulatory pathways involved in fibrotic progression may be a potential therapeutic target of keloids.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.11
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• pp.5709-5714
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• 2012

Objective: To evaluate the effects of curcumin on matrixmetalloproteinase-9 (MMP-9) and invasion ability induced by transforming growth factor-${\beta}1$ (TGF-${\beta}1$) in MDA-MB-231 cells and potential mechanisms. Methods: Human breast cancer MDA-MB-231 cells were used with the CCK-8 assay to measure the cytotoxicity of curcumin. After treatment with 10 ng/ml TGF-${\beta}1$, with or without curcumin (${\leq}10{\mu}M$), cell invasion was checked by transwell chamber. The effects of curcumin on TGF-${\beta}1$-stimulated MMP-9 and phosphorylation of Smad2, extracellular-regulated kinase (ERK), and p38 mitogen activated protein kinases (p38MAPK) were examined by Western blotting. Supernatant liquid were collected to analyze the activity of MMP-9 via zymography. Following treatment with PD98059, a specific inhibitor of ERK, and SB203580, a specific inhibitor of p38MAPK, Western blotting and zymography were employed to examine MMP-9 expression and activity, respectively. Results: Low dose curcumin (${\leq}10{\mu}M$) did not show any obvious toxicity to the cells, while $0{\sim}10{\mu}mol/L$ caused a concentration-dependent reduction in cell invasion provoked by TGF-${\beta}1$. Curcumin also markedly inhibited TGF-${\beta}1$-regulated MMP-9 and activation of Smad2, ERK1/2 and p38 in a dose- and time-dependent manner. Additionally, PD98059, but not SB203580, showed a similar pattern of inhibition of MMP-9 expression. Conclusion: Curcumin inhibited TGF-${\beta}1$-stimulated MMP-9 and the invasive phenotype in MDA-MB-231 cells, possibly associated with TGF-${\beta}$/Smad and TGF-${\beta}$/ERK signaling.

• The Korean Journal of Physiology and Pharmacology
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• v.20 no.3
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• pp.305-314
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• 2016

Inflammatory and fibrotic responses are accelerated during the reperfusion period, and excessive fibrosis and inflammation contribute to cardiac malfunction. NecroX compounds have been shown to protect the liver and heart from ischemia-reperfusion injury. The aim of this study was to further define the role and mechanism of action of NecroX-5 in regulating inflammation and fibrosis responses in a model of hypoxia/reoxygenation (HR). We utilized HR-treated rat hearts and lipopolysaccharide (LPS)-treated H9C2 culture cells in the presence or absence of NecroX-5 ($10{\mu}mol/L$) treatment as experimental models. Addition of NecroX-5 significantly increased decorin (Dcn) expression levels in HR-treated hearts. In contrast, expression of transforming growth factor beta 1 ($TGF{\beta}1$) and Smad2 phosphorylation (pSmad2) was strongly attenuated in NecroX-5-treated hearts. In addition, significantly increased production of tumor necrosis factor alpha ($TNF{\alpha}$), $TGF{\beta}1$, and pSmad2, and markedly decreased Dcn expression levels, were observed in LPS-stimulated H9C2 cells. Interestingly, NecroX-5 supplementation effectively attenuated the increased expression levels of $TNF{\alpha}$, $TGF{\beta}1$, and pSmad2, as well as the decreased expression of Dcn. Thus, our data demonstrate potential antiinflammatory and anti-fibrotic effects of NecroX-5 against cardiac HR injuries via modulation of the $TNF{\alpha}/Dcn/TGF{\beta}1/Smad2$ pathway.