• Journal of Periodontal and Implant Science
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• 제36권4호
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• pp.839-847
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• 2006

The aim of this study is to monitor reporter gene expression under osteocalcin gene promoter, using a real-time molecular imaging system, as tool to investigate osteoblast differentiation. The promoter region of mouse osteocalcin gene 2 (mOG2), the best-characterized osteoblast-specific gene, was inserted in promoterless luciferase reporter vector. Expression of reporter gene was confirmed and relationship between the reporter gene expression and osteoblastic differentiation was evaluated. Gene expression according to osteoblstic differentiation on biomaterials, utilizing a real-time molecular imaging system, was monitored. Luciferase was expressed at the only cells transduced with pGL4/mOGP and the level of expression was statistically higher at cells cultured in mineralization medium than cells in growth medium. CCCD camera detected the luciferase expression and was visible differentiation-dependent intensity of luminescence. The cells produced osteocalcin with time-dependent increment in BMP-2 treated cells and there was difference between BMP-2 treated cells and untreated cells at 14days. There was difference at the level of luciferase expression under pGL4/mOGP between BMP-2 treated cells and untreated cells at 3days. CCCD camera detected the luciferase expression at cells transduced with pGL4/mOGP on Ti disc and was visible differentiation-dependent intensity of luminescence This study shows that 1) expression of luciferase is regulated by the mouse OC promoter, 2) the CCCD detection system is a reliable quantitative gene detection tool for the osteoblast differentiation, 3) the dynamics of mouse OC promoter regulation during osteoblast differentiation is achieved in real time and quantitatively on biomaterial. The present system is a very reliable system for monitoring of osteoblast differentiation in real time and may be used for monitoring the effects of growth factors, drug, cytokines and biomaterials on osteoblast differentiation in animal.

• 대한치주과학회:학술대회논문집
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• 대한치주과학회 2006년도 제46회 종합학술대회 연제초록
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• pp.115-115
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• 2006

• BMB Reports
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• 제47권8호
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• pp.463-468
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• 2014

Osteoblasts are specialized mesenchymal cells that are responsible for bone formation. In this study, we examine the role of GATA4 in osteoblast differentiation. GATA4 was abundantly expressed in preosteoblast cells and gradually down-regulated during osteoblast differentiation. Overexpression of GATA4 in osteoblastic cells inhibited alkaline phosphatase activity and nodule formation in osteogenic conditioned cell culture system. In addition, overexpression of GATA4 attenuated expression of osteogenic marker genes, including Runx2, alkaline phosphatase, bone sialoprotein, and osteocalcin, all of which are important for osteoblast differentiation and function. Overexpression of GATA4 attenuated Runx2 promoter activity, whereas silencing of GATA4 increased Runx2 induction. We found that GATA4 interacted with Dlx5 and subsequently decreased Dlx5 binding activity to Runx2 promoter region. Our data suggest that GATA4 acts as a negative regulator in osteoblast differentiation by downregulation of Runx2.

• Molecules and Cells
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• 제43권1호
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• pp.34-47
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• 2020

The circadian clock regulates various physiological processes, including bone metabolism. The nuclear receptors Reverbs, comprising Rev-erbα and Rev-erbβ, play a key role as transcriptional regulators of the circadian clock. In this study, we demonstrate that Rev-erbs negatively regulate differentiation of osteoclasts and osteoblasts. The knockdown of Rev-erbα in osteoclast precursor cells enhanced receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast formation, as well as expression of nuclear factor of activated T cells 1 (NFATc1), osteoclast-associated receptor (OSCAR), and tartrate-resistant acid phosphatase (TRAP). The overexpression of Rev-erbα leads to attenuation of the NFATc1 expression via inhibition of recruitment of c-Fos to the NFATc1 promoter. The overexpression of Rev-erbα in osteoblast precursors attenuated the expression of osteoblast marker genes including Runx2, alkaline phosphatase (ALP), bone sialoprotein (BSP), and osteocalcin (OC). Rev-erbα interfered with the recruitment of Runx2 to the promoter region of the target genes. Conversely, knockdown of Rev-erbα in the osteoblast precursors enhanced the osteoblast differentiation and function. In addition, Rev-erbα negatively regulated osteoclast and osteoblast differentiation by suppressing the p38 MAPK pathway. Furthermore, intraperitoneal administration of GSK4112, a Rev-erb agonist, protects RANKL-induced bone loss via inhibition of osteoclast differentiation in vivo. Taken together, our results demonstrate a molecular mechanism of Rev-erbs in the bone remodeling, and provide a molecular basis for a potential therapeutic target for treatment of bone disease characterized by excessive bone resorption.

• Journal of Periodontal and Implant Science
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• 제40권1호
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• pp.39-44
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• 2010

Purpose: Bone tissues for clinical application can be improved by studies on osteoblast differentiation. Runx2 is known to be an important transcription factor for osteoblast differentiation. However, bone morphogenetic protein (BMP)-2 treatment to stimulate Runx2 is not sufficient to acquire enough bone formation in osteoblasts. Therefore, it is necessary to find other regulatory factors which can improve the transcriptional activity of Runx2. The erythroblast transformation-specific (ETS) transcription factor family is reported to be involved in various aspects of cellular proliferation and differentiation. Methods: We have noticed that the promoters of osteoblast differentiation markers such as alkaline phosphatase (Alp), osteopontin (Opn), and osteocalcin (Oc) contain Ets binding sequences which are also close to Runx2 binding elements. Luciferase assays were performed to measure the promoter activities of these osteoblast differentiation markers after the transfection of Runx2, myeloid Elf-1-like factor (MEF), and Runxs+MEF. Reverse-transcription polymerase chain reaction was also done to check the mRNA levels of Opn after Runx2 and MEF transfection into rat osteoblast (ROS) cells. Results: We have found that MEF, an Ets transcription factor, increased the transcriptional activities of Alp, Opn, and Oc. The addition of Runx2 resulted in the 2- to 6-fold increase of the activities. This means that these two transcription factors have a synergistic effect on the osteoblast differentiation markers. Furthermore, early introduction of these two Runx2 and MEF factors significantly elevated the expression of the Opn mRNA levels in ROS cells. We also showed that Runx2 and MEF proteins physically interact with each other. Conclusions: Runx2 interacts with MEF proteins and binds to the promoters of the osteoblast markers such as Opn nearby MEF to increase its transcriptional activity. Our results also imply that osteoblast differentiation and bone formation can be increased by activating MEF to elicit the synergistic effect of Runx2 and MEF.

• 대한소아치과학회지
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• 제45권2호
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• pp.144-153
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• 2018

본 연구는 치근 및 치주조직의 형성과정동안 Sonic Hedgehog (SHH) signaling의 역할에 대해 알아보고자 치성간엽에서 조직특이적으로 Smoothened (Smo)가 활성화 또는 차단되는 mouse를 제작하여 분석하였다. 생후 28일경 Smo 활성화모델에서는 H-E 염색 시 얇은 두께의 치근상아질, 넓어진 치수강, 치주인대공간에 느슨하게 배열되어있는 섬유들이 관찰되었다. 면역조직화학염색 시 Smo 활성화모델은 wild type mouse와 비교하여 백악질, 치주인대 그리고/또는 백악모세포의 표식자인 Bsp, Dmp1, Periostin, Ank 같은 기질 단백질들의 발현이 현저히 감소하였다. 그러나 Smo 차단모델은 wild type mouse와 비교하여 이러한 기질 단백질들의 발현에 차이가 보이지 않았다. 본 연구를 통하여 치근 및 치주조직의 정상적인 형성과정에 낮은 수준으로 조절되는 SHH signaling이 필요하다는 것을 확인할 수 있었다.

• 생명과학회지
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• 제27권5호
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• pp.501-508
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• 2017

Bone morphogenetic proteins (BMPs)는 다양한 세포기능을 조절하는 중요한 사이토카인 중 하나이다. 최근 BMP와 일주기 유전자들이 연관되어 있다는 연구결과들이 보고되고 있지만 조골세포에서 일주기 유전자인 Per1의 역할은 아직 명확하지 않다. 본 연구에서는 조골세포 분화에서 Per1의 역할을 조사하였다. MC3T3-E1 세포에서 BMP2 처리에 의해 Per1 mRNA 발현과 luciferase 활성이 증가하는 것을 확인하였다. 또한 Per1 과발현 실험을 통해서 Per1 유전자가 Runx2, ALP, OC의 발현을 증가시켰으며 ascorbic acid와 ${\beta}$-glycerophosphate에 의한 ALP 염색과 석회화가 Per1 과발현에 의해 더욱 증가하는 것을 확인하였다. 이상의 결과는 일주기 리듬을 조절하는 Per1 유전자가 조골세포의 분화를 촉진하는 인자로 작용함을 시사한다.

• International Journal of Oral Biology
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• 제32권4호
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• pp.119-125
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• 2007

Dlx3 is a homeodomain protein and is known to play a role in development and differentiation of many tissues. Deletion of four base pairs in DLX3 (NT3198) is causally related to tricho-dento-osseous (TDO) syndrome (OMIM #190320), a genetic disorder manifested by taurodontism, hair abnormalities, and increased bone density in the cranium. The molecular mechanisms that explain the phenotypic characteristics of TDO syndrome have not been clearly determined. In this study, we examined phenotypic characteristics of wild type DLX3(wtDlx3) and 4-BP DEL DLX3 (TDO mtDlx3) in C2C12 cells. To investigate how wtDlx3 and TDO mtDlx3 differentially regulate osteoblastic differentiation, reporter assays were performed by using luciferase reporters containing the promoters of alkaline phosphatase, bone sialoprotein or osteocalcin. Both wtDlx3 and TDO mtDlx3 enhanced significantly all the reporter activities but the effect of mtDlx3 was much weaker than that of wtDlx3. In spite of these differences in reporter activity, electrophoretic mobility shift assay showed that both wtDlx3 and TDO mtDlx3 formed similar amounts of DNA binding complexes with Dlx3 binding consensus sequence or with ALP promoter oligonucleotide bearing the Dlx3 binding core sequence. TDO mtDlx3 exhibits a longer half-life than wtDlx3 and it corresponds to PESTfind analysis result showing that potential PEST sequence was missed in carboxy terminal of TDO mtDlx3. In addition, co-immunoprecipitation demonstrated that TDO mtDlx3 binds to Msx2 more strongly than wtDlx3. Taken together, though TDO mtDlx3 acted as a weaker transcriptional activator than wtDlx3 in osteoblastic cells, there is possibility that during in vivo osteoblast differentiation TDO mtDlx3 may antagonize transcriptional repressor activity of Msx2 more effectively and for longer period than wtDlx3, resulting in enhancement of osteoblast differentiation.