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Joo-cheol Park – One of the best experts on this subject based on the ideXlab platform.

  • The Nfic-osterix pathway regulates Ameloblast differentiation and enamel formation
    Cell and Tissue Research, 2018
    Co-Authors: Joo-cheol Park
    Abstract:

    Enamel makes up the outermost layer of the crown and its hardness protects other dental tissues from various stimuli. Enamel cannot be regenerated once damaged because Ameloblasts are lost during the tooth eruption. Since the Ameloblast differentiation mechanism is still unknown, further research is essential for developing treatments for defective or damaged enamel. Previously, we have reported that osteoblast differentiation and bone formation were regulated through the runt-related transcription factor 2 (Runx2)-nuclear factor 1-C (Nfic)-osterix (Osx) pathway where Nfic directly controls Osx expression. This pathway regulates odontoblast differentiation and dentin formation as well. The aim of this study was to investigate if the same pathway is applicable for Ameloblast differentiation. Structural enamel defects with disorganized Ameloblasts and decreased proliferation activity of the cervical loop were observed in Nfic ^−/− mice incisors. Expression of the Ameloblast differentiation markers was also downregulated significantly in Nfic ^−/− mice. Real-time PCR analyses suggested that Runx2, Nfic, and Osx regulate the expression of Ameloblast differentiation markers, where Runx2 is upstream of Nfic, and Nfic controls Osx expression. Therefore, we suggest the Runx2-Nfic-Osx pathway as one of the key factors that regulate Ameloblast differentiation.

  • dental follicle cells and cementoblasts induce apoptosis of Ameloblast lineage and hertwig s epithelial root sheath epithelial rests of malassez cells through the fas fas ligand pathway
    European Journal of Oral Sciences, 2012
    Co-Authors: Jihyun Lee, Dongseol Lee, Hyun Nam, Gene Lee, Byoungmoo Seo, Youngsik Cho, Hyunsook Bae, Joo-cheol Park
    Abstract:

    Lee J-H, Lee D-S, Nam H, Lee G, Seo B-M, Cho Y-S, Bae H-S, Park J-C. Dental follicle cells and cementoblasts induce apoptosis of Ameloblast-lineage and Hertwig’s epithelial root sheath/epithelial rests of Malassez cells through the Fas–Fas ligand pathway. Eur J Oral Sci 2012; 120: 29–37. © 2011 Eur J Oral Sci Hertwig’s epithelial root sheath (HERS), epithelial rests of Malassez (ERM) cells, and reduced Ameloblasts undergo apoptosis during tooth development. This study examined the effects of dental follicle cells and cementoblasts on the apoptosis of Ameloblast-lineage and HERS/ERM cells derived from the enamel organ. We also elucidated the induction pathways and identified the apoptotic pathway involved in this process. Here, we showed terminal deoxynucleotidyl transferase-mediated biotin–dUTP nick-end labeling (TUNEL)-positive HERS cells and reduced Ameloblasts near dental follicle cells during tooth development. Co-culturing Ameloblast-lineage cell line (ALC) Ameloblasts and HERS/ERM cells with either dental follicle cells or OCCM-30 cementoblasts markedly enhanced the apoptosis of Ameloblasts and HERS/ERM cells compared with cells cultured alone. However, dental follicle cells and cementoblasts did not modulate the apoptotic responses of co-cultured non-odontogenic MCF10A or KB cells. When Ameloblasts + HERS and cementoblasts + dental follicle cells were co-cultured, the expression of Fas ligand (FasL) increased in cementoblasts + dental follicle cells, while the expression of Fas increased in Ameloblasts + HERS. Interestingly, recombinant FasL induced Ameloblast apoptosis while the cementoblast-induced Ameloblast apoptosis was suppressed by the Fas/FasL antagonist Kp7-6. These results suggest that during tooth development, dental follicle cells and cementoblasts induce apoptosis of Ameloblast-lineage and HERS/ERM cells through the Fas–FasL pathway, but do not induce the apoptosis of non-odontogenic epithelial cells.

  • Odontogenic Ameloblasts‐associated protein (ODAM), via phosphorylation by bone morphogenetic protein receptor type IB (BMPR–IB), is implicated in Ameloblast differentiation
    Journal of cellular biochemistry, 2012
    Co-Authors: Hye Kyung Lee, Youngsik Cho, Hyunsook Bae, Jong-tae Park, Moon-il Cho, Joo-cheol Park
    Abstract:

    To elucidate the function of the odontogenic Ameloblast-associated protein (ODAM) in Ameloblasts, we identified more than 74 proteins that interact with ODAM using protoarray. Of the identified proteins, bone morphogenetic protprotein receptor type-IB (BMPR-IB) was physiologically relevant in differentiating Ameloblasts. ODAM and BMPR-IB exhibited similar patterns of expression in vitro, during Ameloblast differentiation. ODAM and BMPR-IB interacted through the C-terminus of ODAM, which resulted in increased ODAM phosphorylation in the presence of bone morphogenetic protprotein 2 (BMP-2). Immunoprecipitation assays using Ser-Xaa-Glu (SXE) mutants of ODAM demonstrated that the phosphorylation of ODAM by BMPR-IB occurs at this motif, and this phosphorylation is required for the activation of MAPKs. ODAM phosphorylation was detected in Ameloblasts during Ameloblast differentiation and enamel mineralization in vitro and involved in the activation of downstream factors of MAPKs. Therefore, the BMP-2-BMPR-IB-ODAM-MAPK signaling cascade has important roles in Ameloblast differentiation and enamel mineralization. Our data suggest that ODAM facilitates the progression of tooth development in cooperation with BMPR-IB through distinct domains of ODAM.

Hye Kyung Lee – One of the best experts on this subject based on the ideXlab platform.

  • Odontogenic Ameloblasts‐associated protein (ODAM), via phosphorylation by bone morphogenetic protein receptor type IB (BMPR–IB), is implicated in Ameloblast differentiation
    Journal of cellular biochemistry, 2012
    Co-Authors: Hye Kyung Lee, Youngsik Cho, Hyunsook Bae, Jong-tae Park, Moon-il Cho, Joo-cheol Park
    Abstract:

    To elucidate the function of the odontogenic Ameloblast-associated protein (ODAM) in Ameloblasts, we identified more than 74 proteins that interact with ODAM using protoarray. Of the identified proteins, bone morphogenetic protein receptor type-IB (BMPR-IB) was physiologically relevant in differentiating Ameloblasts. ODAM and BMPR-IB exhibited similar patterns of expression in vitro, during Ameloblast differentiation. ODAM and BMPR-IB interacted through the C-terminus of ODAM, which resulted in increased ODAM phosphorylation in the presence of bone morphogenetic protein 2 (BMP-2). Immunoprecipitation assays using Ser-Xaa-Glu (SXE) mutants of ODAM demonstrated that the phosphorylation of ODAM by BMPR-IB occurs at this motif, and this phosphorylation is required for the activation of MAPKs. ODAM phosphorylation was detected in Ameloblasts during Ameloblast differentiation and enamel mineralization in vitro and involved in the activation of downstream factors of MAPKs. Therefore, the BMP-2-BMPR-IB-ODAM-MAPK signaling cascade has important roles in Ameloblast differentiation and enamel mineralization. Our data suggest that ODAM facilitates the progression of tooth development in cooperation with BMPR-IB through distinct domains of ODAM.

  • odontogenic Ameloblasts associated protein odam via phosphorylation by bone morphogenetic protein receptor type ib bmpr ib is implicated in Ameloblast differentiation
    Journal of Cellular Biochemistry, 2011
    Co-Authors: Hye Kyung Lee, Youngsik Cho, Hyunsook Bae, Jong-tae Park, Moon-il Cho, Joo-cheol Park
    Abstract:

    To elucidate the function of the odontogenic Ameloblast-associated protein (ODAM) in Ameloblasts, we identified more than 74 proteins that interact with ODAM using protoarray. Of the identified proteins, bone morphogenetic protprotein receptor type-IB (BMPR-IB) was physiologically relevant in differentiating Ameloblasts. ODAM and BMPR-IB exhibited similar patterns of expression in vitro, during Ameloblast differentiation. ODAM and BMPR-IB interacted through the C-terminus of ODAM, which resulted in increased ODAM phosphorylation in the presence of bone morphogenetic protprotein 2 (BMP-2). Immunoprecipitation assays using Ser-Xaa-Glu (SXE) mutants of ODAM demonstrated that the phosphorylation of ODAM by BMPR-IB occurs at this motif, and this phosphorylation is required for the activation of MAPKs. ODAM phosphorylation was detected in Ameloblasts during Ameloblast differentiation and enamel mineralization in vitro and involved in the activation of downstream factors of MAPKs. Therefore, the BMP-2-BMPR-IB-ODAM-MAPK signaling cascade has important roles in Ameloblast differentiation and enamel mineralization. Our data suggest that ODAM facilitates the progression of tooth development in cooperation with BMPR-IB through distinct domains of ODAM.

  • the odontogenic Ameloblast associated protein odam cooperates with runx2 and modulates enamel mineralization via regulation of mmp 20
    Journal of Cellular Biochemistry, 2010
    Co-Authors: Hye Kyung Lee, Dongseol Lee, Hyunsook Bae, Jong-tae Park, Moon-il Cho, Hyunmo Ryoo, Sujin Park, Joo-cheol Park
    Abstract:

    We have previously reported that the odontogenic Ameloblast-associated protein (ODAM) plays important roles in enamel mineralization through the regulation of matrix metalloproteinase-20 (MMP-20). However, the precise function of ODAM in MMP-20 regulation remains largely unknown. The aim of the present study was to uncover the molecular mechanisms responsible for MMP-20 regulation. The subcellular localization of ODAM varies in a stage-specific fashion during Ameloblast differentiation. During the secretory stage of amelogenesis ODAM was localized to both the nucleus and cytoplasm of Ameloblasts. However, during the maturation stage of amelogenesis, ODAM was observed in the cytoplasm and at the interface between Ameloblasts and the enamel layer, but not in the nucleus. Secreted ODAM was detected in the conditioned medium of Ameloblast-lineage cell line (ALC) from days 14 to 21, which coincided with the maturation stage of amelogenesis. Interestingly, the expression of Runx2 and nuclear ODAM correlated with MMP-20 expression in ALC. We therefore examined whether ODAM cooperates with Runx2 to regulate MMP-20 and modulate enamel mineralization. Increased expression of ODAM and Runx2 augmented MMP-20 expression, and Runx2 expression enhanced expression of ODAM, although overexpression of ODAM did not influence Runx2 expression. Conversely, loss of Runx2 in ALC decreased ODAM expression, resulting in down-regulation of MMP-20 expression. Increased MMP-20 expression accelerated amelogenin processing during enamel mineralization. Our data suggest that Runx2 regulates the expression of ODAM and that nuclear ODAM serves an important regulatory function in the mineralization of enamel through the regulation of MMP-20 apart from a different, currently unidentified, function of extracellular ODAM. J. Cell. Biochem. 111: 755–767, 2010. © 2010 Wiley-Liss, Inc.

John D. Bartlett – One of the best experts on this subject based on the ideXlab platform.

  • mmp20 overexpression disrupts molar Ameloblast polarity and migration
    Journal of Dental Research, 2018
    Co-Authors: M. Shin, M B Chavez, A Ikeda, Brian L. Foster, John D. Bartlett
    Abstract:

    Ameloblasts responsible for enamel formation express matrix metalloproteinase 20 (MMP20), an enzyme that cleaves enamel matrix proteins, including amelogenin (AMELX) and Ameloblastin (AMBN). Previously, we showed that continuously erupting incisors from transgenic mice overexpressing active MMP20 had a massive cell infiltrate present within their enamel space, leading to enamel mineralization defects. However, effects of MMP20 overexpression on mouse molars were not analyzed, although these teeth more accurately represent human odontogenesis. Therefore, MMP20-overexpressing mice (Mmp20+/+Tg+) were assessed by multiscale analyses, combining several approaches from high-resolution micro–computed tomography to enamel organ immunoblots. During the secretory stage at postnatal day 6 (P6), Mmp20+/+Tg+ mice had a discontinuous Ameloblast layer and, unlike incisors, molar P12 maturation stage Ameloblasts abnormally migrated away from the enamel layer into the stratum intermedium/stellate retireticulum. TOPflash assay…

  • Murine matrix metalloproteinase-20 overexpression stimulates cell invasion into the enamel layer via enhanced Wnt signaling
    Scientific Reports, 2016
    Co-Authors: Masashi Shin, Maiko Suzuki, Xiaomu Guan, Charles E Smith, John D. Bartlett
    Abstract:

    Matrix metalloproteinase-20 (MMP20) is expressed by Ameloblasts in developing teeth and MMP20 mutations cause enamel malformation. We established a stably transfected Tet-Off Mmp20-inducible Ameloblast-lineage cell line and found that MMP20 expression promoted cell invasion. Previously, we engineered transgenic mice (Tg) that drive Mmp20 expression and showed that Mmp20+/+Tg mice had soft enamel. Here we asked if Mmp20 overexpression disrupts Ameloblast function. Incisors from Mmp20+/+ mice expressing the Mmp20 Tg had a striking cell infiltrate which nearly replaced the entire enamel layer. A thin layer of enamel-like material remained over the dentin and at the outer tooth surface, but between these regions were invading fibroblasts and epithelial cells that surrounded ectopic bone-like calcifications. Mmp20+/+Tg mice had decreased enamel organ cadherin levels compared to the Mmp20 ablated and WT mice and, instead of predominantly locating adjacent to the Ameloblast cell membrane, β-catenin was predominantly present within the nuclei of invading cells. Our data suggest that increased cadherin cleavage by transgenic MMP20 in the WT background releases excess β-catenin, which translocates to Ameloblast nuclei to promote cell migration/invasion. Therefore, we conclude that MMP20 plays a role in normal Ameloblast migration through tightly controlled Wnt signaling and that MMP20 overexpression disrupts this process.

  • mmp20 modulates cadherin expression in Ameloblasts as enamel develops
    Journal of Dental Research, 2013
    Co-Authors: Xiaomu Guan, John D. Bartlett
    Abstract:

    Matrix metalloproteinase-20 (enamelysin, MMP20) is essential for dental enamel development. Seven different MMP20 mutations in humans cause non-syndromic enamel malformations, termed amelogenesis imperfecta, and ablation of Mmp20 in mice results in thin brittle enamel with a dysplastic rod pattern. Healthy enamel formation requires the sliding movement of Ameloblasts in rows during the secretory stage of development. This is essential for formation of the characteristic decussating enamel rod pattern observed in rodents, and this is also when MMP20 is secreted into the enamel matrix. Therefore, we propose that MMP20 facilitates Ameloblast movement by cleaving Ameloblast cell-cell contacts. Here we show that MMP20 cleaves the extracellular domains of the E- and N-cadherin adherens junction proteins, that both E- and N-cadherin transcripts are expressed at significantly higher levels in Mmp20 null vs. wild-type (WT) mice, and that in Mmp20 ablated mice, high-level Ameloblast N-cadherin expression persists during the maturation stage of development. Furthermore, we show that E-cadherin gene expression is down-regulated from the pre-secretory to the secretory stage, while N-cadherin levels are up-regulated. This E- to N-cadherin switch supports epithelial migration in other tissues and may be an important event necessary for the Ameloblasts to start moving in rows that slide by one another.

Jong-tae Park – One of the best experts on this subject based on the ideXlab platform.

  • Odontogenic Ameloblasts‐associated protein (ODAM), via phosphorylation by bone morphogenetic protein receptor type IB (BMPR–IB), is implicated in Ameloblast differentiation
    Journal of cellular biochemistry, 2012
    Co-Authors: Hye Kyung Lee, Youngsik Cho, Hyunsook Bae, Jong-tae Park, Moon-il Cho, Joo-cheol Park
    Abstract:

    To elucidate the function of the odontogenic Ameloblast-associated protein (ODAM) in Ameloblasts, we identified more than 74 proteins that interact with ODAM using protoarray. Of the identified proteins, bone morphogenetic protein receptor type-IB (BMPR-IB) was physiologically relevant in differentiating Ameloblasts. ODAM and BMPR-IB exhibited similar patterns of expression in vitro, during Ameloblast differentiation. ODAM and BMPR-IB interacted through the C-terminus of ODAM, which resulted in increased ODAM phosphorylation in the presence of bone morphogenetic protein 2 (BMP-2). Immunoprecipitation assays using Ser-Xaa-Glu (SXE) mutants of ODAM demonstrated that the phosphorylation of ODAM by BMPR-IB occurs at this motif, and this phosphorylation is required for the activation of MAPKs. ODAM phosphorylation was detected in Ameloblasts during Ameloblast differentiation and enamel mineralization in vitro and involved in the activation of downstream factors of MAPKs. Therefore, the BMP-2-BMPR-IB-ODAM-MAPK signaling cascade has important roles in Ameloblast differentiation and enamel mineralization. Our data suggest that ODAM facilitates the progression of tooth development in cooperation with BMPR-IB through distinct domains of ODAM.

  • odontogenic Ameloblasts associated protein odam via phosphorylation by bone morphogenetic protein receptor type ib bmpr ib is implicated in Ameloblast differentiation
    Journal of Cellular Biochemistry, 2011
    Co-Authors: Hye Kyung Lee, Youngsik Cho, Hyunsook Bae, Jong-tae Park, Moon-il Cho, Joo-cheol Park
    Abstract:

    To elucidate the function of the odontogenic Ameloblast-associated protein (ODAM) in Ameloblasts, we identified more than 74 proteins that interact with ODAM using protoarray. Of the identified proteins, bone morphogenetic protein receptor type-IB (BMPR-IB) was physiologically relevant in differentiating Ameloblasts. ODAM and BMPR-IB exhibited similar patterns of expression in vitro, during Ameloblast differentiation. ODAM and BMPR-IB interacted through the C-terminus of ODAM, which resulted in increased ODAM phosphorylation in the presence of bone morphogenetic protein 2 (BMP-2). Immunoprecipitation assays using Ser-Xaa-Glu (SXE) mutants of ODAM demonstrated that the phosphorylation of ODAM by BMPR-IB occurs at this motif, and this phosphorylation is required for the activation of MAPKs. ODAM phosphorylation was detected in Ameloblasts during Ameloblast differentiation and enamel mineralization in vitro and involved in the activation of downstream factors of MAPKs. Therefore, the BMP-2-BMPR-IB-ODAM-MAPK signaling cascade has important roles in Ameloblast differentiation and enamel mineralization. Our data suggest that ODAM facilitates the progression of tooth development in cooperation with BMPR-IB through distinct domains of ODAM.

  • the odontogenic Ameloblast associated protein odam cooperates with runx2 and modulates enamel mineralization via regulation of mmp 20
    Journal of Cellular Biochemistry, 2010
    Co-Authors: Hye Kyung Lee, Dongseol Lee, Hyunsook Bae, Jong-tae Park, Moon-il Cho, Hyunmo Ryoo, Sujin Park, Joo-cheol Park
    Abstract:

    We have previously reported that the odontogenic Ameloblast-associated protein (ODAM) plays important roles in enamel mineralization through the regulation of matrix metalloproteinase-20 (MMP-20). However, the precise function of ODAM in MMP-20 regulation remains largely unknown. The aim of the present study was to uncover the molecular mechanisms responsible for MMP-20 regulation. The subcellular localization of ODAM varies in a stage-specific fashion during Ameloblast differentiation. During the secretory stage of amelogenesis ODAM was localized to both the nucleus and cytoplasm of Ameloblasts. However, during the maturation stage of amelogenesis, ODAM was observed in the cytoplasm and at the interface between Ameloblasts and the enamel layer, but not in the nucleus. Secreted ODAM was detected in the conditioned medium of Ameloblast-lineage cell line (ALC) from days 14 to 21, which coincided with the maturation stage of amelogenesis. Interestingly, the expression of Runx2 and nuclear ODAM correlated with MMP-20 expression in ALC. We therefore examined whether ODAM cooperates with Runx2 to regulate MMP-20 and modulate enamel mineralization. Increased expression of ODAM and Runx2 augmented MMP-20 expression, and Runx2 expression enhanced expression of ODAM, although overexpression of ODAM did not influence Runx2 expression. Conversely, loss of Runx2 in ALC decreased ODAM expression, resulting in down-regulation of MMP-20 expression. Increased MMP-20 expression accelerated amelogenin processing during enamel mineralization. Our data suggest that Runx2 regulates the expression of ODAM and that nuclear ODAM serves an important regulatory function in the mineralization of enamel through the regulation of MMP-20 apart from a different, currently unidentified, function of extracellular ODAM. J. Cell. Biochem. 111: 755–767, 2010. © 2010 Wiley-Liss, Inc.

Moon-il Cho – One of the best experts on this subject based on the ideXlab platform.

  • Odontogenic Ameloblasts‐associated protein (ODAM), via phosphorylation by bone morphogenetic protein receptor type IB (BMPR–IB), is implicated in Ameloblast differentiation
    Journal of cellular biochemistry, 2012
    Co-Authors: Hye Kyung Lee, Youngsik Cho, Hyunsook Bae, Jong-tae Park, Moon-il Cho, Joo-cheol Park
    Abstract:

    To elucidate the function of the odontogenic Ameloblast-associated protein (ODAM) in Ameloblasts, we identified more than 74 proteins that interact with ODAM using protoarray. Of the identified proteins, bone morphogenetic protein receptor type-IB (BMPR-IB) was physiologically relevant in differentiating Ameloblasts. ODAM and BMPR-IB exhibited similar patterns of expression in vitro, during Ameloblast differentiation. ODAM and BMPR-IB interacted through the C-terminus of ODAM, which resulted in increased ODAM phosphorylation in the presence of bone morphogenetic protein 2 (BMP-2). Immunoprecipitation assays using Ser-Xaa-Glu (SXE) mutants of ODAM demonstrated that the phosphorylation of ODAM by BMPR-IB occurs at this motif, and this phosphorylation is required for the activation of MAPKs. ODAM phosphorylation was detected in Ameloblasts during Ameloblast differentiation and enamel mineralization in vitro and involved in the activation of downstream factors of MAPKs. Therefore, the BMP-2-BMPR-IB-ODAM-MAPK signaling cascade has important roles in Ameloblast differentiation and enamel mineralization. Our data suggest that ODAM facilitates the progression of tooth development in cooperation with BMPR-IB through distinct domains of ODAM.

  • odontogenic Ameloblasts associated protein odam via phosphorylation by bone morphogenetic protein receptor type ib bmpr ib is implicated in Ameloblast differentiation
    Journal of Cellular Biochemistry, 2011
    Co-Authors: Hye Kyung Lee, Youngsik Cho, Hyunsook Bae, Jong-tae Park, Moon-il Cho, Joo-cheol Park
    Abstract:

    To elucidate the function of the odontogenic Ameloblast-associated protein (ODAM) in Ameloblasts, we identified more than 74 proteins that interact with ODAM using protoarray. Of the identified proteins, bone morphogenetic protein receptor type-IB (BMPR-IB) was physiologically relevant in differentiating Ameloblasts. ODAM and BMPR-IB exhibited similar patterns of expression in vitro, during Ameloblast differentiation. ODAM and BMPR-IB interacted through the C-terminus of ODAM, which resulted in increased ODAM phosphorylation in the presence of bone morphogenetic protein 2 (BMP-2). Immunoprecipitation assays using Ser-Xaa-Glu (SXE) mutants of ODAM demonstrated that the phosphorylation of ODAM by BMPR-IB occurs at this motif, and this phosphorylation is required for the activation of MAPKs. ODAM phosphorylation was detected in Ameloblasts during Ameloblast differentiation and enamel mineralization in vitro and involved in the activation of downstream factors of MAPKs. Therefore, the BMP-2-BMPR-IB-ODAM-MAPK signaling cascade has important roles in Ameloblast differentiation and enamel mineralization. Our data suggest that ODAM facilitates the progression of tooth development in cooperation with BMPR-IB through distinct domains of ODAM.

  • the odontogenic Ameloblast associated protein odam cooperates with runx2 and modulates enamel mineralization via regulation of mmp 20
    Journal of Cellular Biochemistry, 2010
    Co-Authors: Hye Kyung Lee, Dongseol Lee, Hyunsook Bae, Jong-tae Park, Moon-il Cho, Hyunmo Ryoo, Sujin Park, Joo-cheol Park
    Abstract:

    We have previously reported that the odontogenic Ameloblast-associated protein (ODAM) plays important roles in enamel mineralization through the regulation of matrix metalloproteinase-20 (MMP-20). However, the precise function of ODAM in MMP-20 regulation remains largely unknown. The aim of the present study was to uncover the molecular mechanisms responsible for MMP-20 regulation. The subcellular localization of ODAM varies in a stage-specific fashion during Ameloblast differentiation. During the secretory stage of amelogenesis ODAM was localized to both the nucleus and cytoplasm of Ameloblasts. However, during the maturation stage of amelogenesis, ODAM was observed in the cytoplasm and at the interface between Ameloblasts and the enamel layer, but not in the nucleus. Secreted ODAM was detected in the conditioned medium of Ameloblast-lineage cell line (ALC) from days 14 to 21, which coincided with the maturation stage of amelogenesis. Interestingly, the expression of Runx2 and nuclear ODAM correlated with MMP-20 expression in ALC. We therefore examined whether ODAM cooperates with Runx2 to regulate MMP-20 and modulate enamel mineralization. Increased expression of ODAM and Runx2 augmented MMP-20 expression, and Runx2 expression enhanced expression of ODAM, although overexpression of ODAM did not influence Runx2 expression. Conversely, loss of Runx2 in ALC decreased ODAM expression, resulting in down-regulation of MMP-20 expression. Increased MMP-20 expression accelerated amelogenin processing during enamel mineralization. Our data suggest that Runx2 regulates the expression of ODAM and that nuclear ODAM serves an important regulatory function in the mineralization of enamel through the regulation of MMP-20 apart from a different, currently unidentified, function of extracellular ODAM. J. Cell. Biochem. 111: 755–767, 2010. © 2010 Wiley-Liss, Inc.