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Shemirani R, Lin G, Abduweli Uyghurturk D, Le M, Nakano Y. An miRNA derived from amelogenin exon4 regulates expression of transcription factor Runx2 by directly targeting upstream activators Nfia and Prkch. J Biol Chem 2022; 298:101807. [PMID: 35271849 PMCID: PMC9061250 DOI: 10.1016/j.jbc.2022.101807] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 03/02/2022] [Accepted: 03/04/2022] [Indexed: 11/30/2022] Open
Abstract
Amel, the gene encoding the amelogenin protein involved in enamel formation, is highly alternatively spliced. When exon4 is excised, it can form a mature miRNA (miR-exon4) that has previously been suggested to indirectly regulate expression of the Runt-related transcription factor 2 (Runx2) involved in bone development in ameloblasts and osteoblasts. However, the precise mechanism of this regulation is unclear. In this study, we aimed to identify direct targets of miR-exon4. The transcription factor family nuclear factor I/A (NFI/A) is known to negatively regulate expression of Runx2 and is among the most highly predicted direct targets of miR-exon4 that link to Runx2. Immunostaining detected NFI/A in osteoblasts and ameloblasts in vivo, and reporter assays confirmed direct interaction of the Nfia 3'-UTR and miR-exon4. In addition, silencing of Nfia in MC3T3-E1-M14 osteoblasts resulted in subsequent downregulation of Runx2. In a monoclonal subclone (mi2) of MC3T3-E1 cells wherein mature miR-exon4 was functionally inhibited, we observed significantly downregulated Runx2 expression. We showed that NFI/A was significantly upregulated in mi2 cells at both mRNA and protein levels. Furthermore, quantitative proteomics and pathway analysis of gene expression in mi2 cells suggested that miR-exon4 could directly target Prkch (protein kinase C-eta), possibly leading to RUNX2 regulation through mechanistic target of rapamycin kinase activation. Reporter assays also confirmed the direct interaction of miR-exon4 and the 3'-UTR of Prkch, and Western blot analysis confirmed significantly upregulated mechanistic target of rapamycin kinase phosphorylation in mi2 cells. Taken together, we conclude that Nfia and Prkch expression negatively correlates with miR-exon4-mediated Runx2 regulation in vivo and in vitro, suggesting miR-exon4 directly targets Nfia and Prkch to regulate Runx2.
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Affiliation(s)
- Rozana Shemirani
- Department of Orofacial Sciences, School of Dentistry, University of California, San Francisco, USA
| | - Gan Lin
- Department of Orofacial Sciences, School of Dentistry, University of California, San Francisco, USA
| | | | - Michael Le
- Department of Preventive and Restorative Dental Sciences, School of Dentistry, University of California, San Francisco, USA
| | - Yukiko Nakano
- Department of Orofacial Sciences, School of Dentistry, University of California, San Francisco, USA; Center for Children's Oral Health Research, School of Dentistry, University of California, San Francisco, USA.
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Amelogenin-Derived Peptides in Bone Regeneration: A Systematic Review. Int J Mol Sci 2021; 22:ijms22179224. [PMID: 34502132 PMCID: PMC8431254 DOI: 10.3390/ijms22179224] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 08/03/2021] [Accepted: 08/11/2021] [Indexed: 11/17/2022] Open
Abstract
Amelogenins are enamel matrix proteins currently used to treat bone defects in periodontal surgery. Recent studies have highlighted the relevance of amelogenin-derived peptides, named LRAP, TRAP, SP, and C11, in bone tissue engineering. Interestingly, these peptides seem to maintain or even improve the biological activity of the full-length protein, which has received attention in the field of bone regeneration. In this article, the authors combined a systematic and a narrative review. The former is focused on the existing scientific evidence on LRAP, TRAP, SP, and C11's ability to induce the production of mineralized extracellular matrix, while the latter is concentrated on the structure and function of amelogenin and amelogenin-derived peptides. Overall, the collected data suggest that LRAP and SP are able to induce stromal stem cell differentiation towards osteoblastic phenotypes; specifically, SP seems to be more reliable in bone regenerative approaches due to its osteoinduction and the absence of immunogenicity. However, even if some evidence is convincing, the limited number of studies and the scarcity of in vivo studies force us to wait for further investigations before drawing a solid final statement on the real potential of amelogenin-derived peptides in bone tissue engineering.
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Pandya M, Diekwisch TGH. Enamel biomimetics-fiction or future of dentistry. Int J Oral Sci 2019. [PMID: 30610185 DOI: 10.1038/s41368-018-0038-6,1-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/14/2023] Open
Abstract
Tooth enamel is a complex mineralized tissue consisting of long and parallel apatite crystals configured into decussating enamel rods. In recent years, multiple approaches have been introduced to generate or regenerate this highly attractive biomaterial characterized by great mechanical strength paired with relative resilience and tissue compatibility. In the present review, we discuss five pathways toward enamel tissue engineering, (i) enamel synthesis using physico-chemical means, (ii) protein matrix-guided enamel crystal growth, (iii) enamel surface remineralization, (iv) cell-based enamel engineering, and (v) biological enamel regeneration based on de novo induction of tooth morphogenesis. So far, physical synthesis approaches using extreme environmental conditions such as pH, heat and pressure have resulted in the formation of enamel-like crystal assemblies. Biochemical methods relying on enamel proteins as templating matrices have aided the growth of elongated calcium phosphate crystals. To illustrate the validity of this biochemical approach we have successfully grown enamel-like apatite crystals organized into decussating enamel rods using an organic enamel protein matrix. Other studies reviewed here have employed amelogenin-derived peptides or self-assembling dendrimers to re-mineralize mineral-depleted white lesions on tooth surfaces. So far, cell-based enamel tissue engineering has been hampered by the limitations of presently existing ameloblast cell lines. Going forward, these limitations may be overcome by new cell culture technologies. Finally, whole-tooth regeneration through reactivation of the signaling pathways triggered during natural enamel development represents a biological avenue toward faithful enamel regeneration. In the present review we have summarized the state of the art in enamel tissue engineering and provided novel insights into future opportunities to regenerate this arguably most fascinating of all dental tissues.
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Affiliation(s)
- Mirali Pandya
- Center for Craniofacial Research and Diagnosis, Texas A&M College of Dentistry, Dallas, TX, USA
| | - Thomas G H Diekwisch
- Center for Craniofacial Research and Diagnosis, Texas A&M College of Dentistry, Dallas, TX, USA.
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4
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Abstract
Tooth enamel is a complex mineralized tissue consisting of long and parallel apatite crystals configured into decussating enamel rods. In recent years, multiple approaches have been introduced to generate or regenerate this highly attractive biomaterial characterized by great mechanical strength paired with relative resilience and tissue compatibility. In the present review, we discuss five pathways toward enamel tissue engineering, (i) enamel synthesis using physico-chemical means, (ii) protein matrix-guided enamel crystal growth, (iii) enamel surface remineralization, (iv) cell-based enamel engineering, and (v) biological enamel regeneration based on de novo induction of tooth morphogenesis. So far, physical synthesis approaches using extreme environmental conditions such as pH, heat and pressure have resulted in the formation of enamel-like crystal assemblies. Biochemical methods relying on enamel proteins as templating matrices have aided the growth of elongated calcium phosphate crystals. To illustrate the validity of this biochemical approach we have successfully grown enamel-like apatite crystals organized into decussating enamel rods using an organic enamel protein matrix. Other studies reviewed here have employed amelogenin-derived peptides or self-assembling dendrimers to re-mineralize mineral-depleted white lesions on tooth surfaces. So far, cell-based enamel tissue engineering has been hampered by the limitations of presently existing ameloblast cell lines. Going forward, these limitations may be overcome by new cell culture technologies. Finally, whole-tooth regeneration through reactivation of the signaling pathways triggered during natural enamel development represents a biological avenue toward faithful enamel regeneration. In the present review we have summarized the state of the art in enamel tissue engineering and provided novel insights into future opportunities to regenerate this arguably most fascinating of all dental tissues. Five pathways for tooth enamel engineering hold great promise for developing new technologies, leading to novel biomaterials and biotechnologies to regenerate enamel tissue. Tooth enamel is a unique tissue-specific biomaterial with exceptional structural and mechanical properties. In recent years, many approaches have been adopted to generate or regenerate this complex tissue; Mirali Pandya and Thomas Diekwisch of Texas A&M College of Dentistry, USA conducted a review of the current state and future directions of enamel tissue engineering. In their review, the authors focused on five pathways for enamel tissue engineering: (1) physical synthesis of enamel; (2) biochemical enamel engineering; (3) in situ enamel engineering; (4) cell-based enamel engineering; and (5) whole tooth regeneration. The authors conclude that those five approaches will help identify the biological mechanisms that lead to the generation of tooth enamel.
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5
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Kim YJ, Kim YJ, Kang J, Shin TJ, Hyun HK, Lee SH, Lee ZH, Kim JW. A novel AMELX mutation causes hypoplastic amelogenesis imperfecta. Arch Oral Biol 2017; 76:61-65. [DOI: 10.1016/j.archoralbio.2017.01.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Revised: 10/17/2016] [Accepted: 01/03/2017] [Indexed: 10/20/2022]
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Matsuda Y, Hatakeyama Y, Nakashima K, Kamogashira N, Hatakeyama J, Tamaoki S, Sawa Y, Ishikawa H. Effects of a Chemically Synthesized Leucine-Rich Amelogenin Peptide (csLRAP) on Chondrogenic and Osteogenic Cells. J HARD TISSUE BIOL 2017. [DOI: 10.2485/jhtb.26.51] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
| | | | | | | | - Junko Hatakeyama
- Section of Operative Dentistry and Endodontology, Fukuoka Dental College
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7
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Yoo HI, Lee GH, Lee SY, Kang JH, Moon JS, Kim MS, Kim SH. Expression of amelogenin and effects of cyclosporin A in developing hair follicles in rats. J Anat 2015; 228:153-61. [PMID: 26426935 DOI: 10.1111/joa.12387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/27/2015] [Indexed: 11/29/2022] Open
Abstract
Amelogenin, an enamel matrix protein has been considered to be exclusively expressed by ameloblasts during odontogenesis. However, burgeoning evidence indicates that amelogenin is also expressed in non-mineralizing tissues. Under the hypothesis that amelogenin may be a functional molecule in developing hair follicles which share developmental features with odontogenesis, this study for the first time elucidated the presence and functional changes of amelogenin and its receptors during rat hair follicle development. Amelogenin was specifically localized in the outer epithelial root sheath of hair follicles. Its expression appeared in the deeper portion of hair follicles, i.e. the bulbar and suprabulbar regions rather than the superficial region. Lamp-1, an amelogenin receptor, was localized in either follicular cells or outer epithelial sheath cells, reflecting functional changes during development. The expression of amelogenin splicing variants increased in a time-dependent manner during postnatal development of hair follicles. Amelogenin expression was increased by treatment with cyclosporin A, which is an inducer of anagen in the hair follicle, whereas the level of Lamp-1 and -2 was decreased by cyclosporin A treatment. These results suggest that amelogenin may be a functional molecule involved in the development of the hair follicle rather than an inert hair shaft matrix protein.
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Affiliation(s)
- Hong-Il Yoo
- Dental Science Research Institute, School of Dentistry, Chonnam National University, Gwangju, Korea
| | - Gye-Hyeok Lee
- Dental Science Research Institute, School of Dentistry, Chonnam National University, Gwangju, Korea
| | - Su-Young Lee
- Dental Science Research Institute, School of Dentistry, Chonnam National University, Gwangju, Korea
| | - Jee-Hae Kang
- Dental Science Research Institute, School of Dentistry, Chonnam National University, Gwangju, Korea
| | - Jung-Sun Moon
- Dental Science Research Institute, School of Dentistry, Chonnam National University, Gwangju, Korea
| | - Min-Seok Kim
- Dental Science Research Institute, School of Dentistry, Chonnam National University, Gwangju, Korea
| | - Sun-Hun Kim
- Dental Science Research Institute, School of Dentistry, Chonnam National University, Gwangju, Korea
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8
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Stahl J, Nakano Y, Horst J, Zhu L, Le M, Zhang Y, Liu H, Li W, Den Besten PK. Exon4 amelogenin transcripts in enamel biomineralization. J Dent Res 2015; 94:836-42. [PMID: 25792521 PMCID: PMC4485327 DOI: 10.1177/0022034515577412] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Amelogenins are proteins formed by alternative splicing of the amelogenin gene, and are essential for tooth enamel formation. However, the unique functions of various alternatively spliced amelogenins in enamel formation are not well understood. In this study, we determined the spatiotemporal location of amelogenins derived from transcripts containing exon4 (AMG+4) in the enamel matrix, and the relative binding of recombinant AMG+4 to hydroxyapatite (HAP). Immunohistochemistry and mass spectrometry analyses showed that AMG+4 proteins were secreted into the enamel matrix at the early maturation stage. A stage-specific increase in the synthesis of AMG+4 was further supported by our observation that in mice overexpressing leucine-rich amelogenin peptide (TgLRAP), in which ameloblasts differentiate earlier, AMG+4 transcripts were also upregulated earlier. In vitro binding studies, supported by in silico modeling of protein binding to calcium and phosphate, showed that more recombinant AMG+4 bound to hydroxyapatite (HAP) as compared with recombinant AMG-4. The temporal and spatial localization of amelogenins containing exon4 peptide, and their functional differences in HAP binding, suggests that the unique properties of amelogenins containing exon4 cause a specific enhancement of biomineralization related to stabilization of early-formed HAP at the maturation stage.
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Affiliation(s)
- J Stahl
- Department of Orofacial Sciences, University of California, San Francisco, School of Dentistry, San Francisco, CA, USA Maxillofacial Injury and Disease Department, Naval Medical Research Unit, San Antonio, TX, USA
| | - Y Nakano
- Department of Orofacial Sciences, University of California, San Francisco, School of Dentistry, San Francisco, CA, USA
| | - J Horst
- Department of Biochemistry and Biophysics, University of California, San Francisco, School of Medicine, San Francisco, CA, USA
| | - L Zhu
- Department of Orofacial Sciences, University of California, San Francisco, School of Dentistry, San Francisco, CA, USA
| | - M Le
- Department of Orofacial Sciences, University of California, San Francisco, School of Dentistry, San Francisco, CA, USA
| | - Y Zhang
- Department of Orofacial Sciences, University of California, San Francisco, School of Dentistry, San Francisco, CA, USA
| | - H Liu
- Department of Obstetrics, Gynecology & Reproductive Sciences & Sandler-Moore Mass Spectrometry Core Facility, University of California, San Francisco, CA, USA
| | - W Li
- Department of Orofacial Sciences, University of California, San Francisco, School of Dentistry, San Francisco, CA, USA
| | - P K Den Besten
- Department of Orofacial Sciences, University of California, San Francisco, School of Dentistry, San Francisco, CA, USA
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9
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Tarasevich BJ, Philo JS, Maluf NK, Krueger S, Buchko GW, Lin G, Shaw WJ. The leucine-rich amelogenin protein (LRAP) is primarily monomeric and unstructured in physiological solution. J Struct Biol 2015; 190:81-91. [PMID: 25449314 PMCID: PMC4400868 DOI: 10.1016/j.jsb.2014.10.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Revised: 10/17/2014] [Accepted: 10/20/2014] [Indexed: 11/23/2022]
Abstract
Amelogenin proteins are critical to the formation of enamel in teeth and may have roles in controlling growth and regulating microstructures of the intricately woven hydroxyapatite (HAP). Leucine-rich amelogenin protein (LRAP) is a 59-residue splice variant of amelogenin and contains the N- and C-terminal charged regions of the full-length protein thought to control crystal growth. Although the quaternary structure of full-length amelogenin in solution has been well studied and can consist of self-assemblies of monomers called nanospheres, there is limited information on the quaternary structure of LRAP. Here, sedimentation velocity analytical ultracentrifugation (SV) and small angle neutron scattering (SANS) were used to study the tertiary and quaternary structure of LRAP at various pH values, ionic strengths, and concentrations. We found that the monomer is the dominant species of phosphorylated LRAP (LRAP(+P)) over a range of solution conditions (pH 2.7-4.1, pH 4.5-8, 50 mmol/L(mM) to 200 mM NaCl, 0.065-2 mg/mL). The monomer is also the dominant species for unphosphorylated LRAP (LRAP(-P)) at pH 7.4 and for LRAP(+P) in the presence of 2.5 mM calcium at pH 7.4. LRAP aggregates in a narrow pH range near the isoelectric point of pH 4.1. SV and SANS show that the LRAP monomer has a radius of ∼2.0 nm and an asymmetric structure, and solution NMR studies indicate that the monomer is largely unstructured. This work provides new insights into the secondary, tertiary, and quaternary structure of LRAP in solution and provides evidence that the monomeric species may be an important functional form of some amelogenins.
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Affiliation(s)
| | - John S Philo
- Alliance Protein Laboratories, Inc., San Diego, CA 92121, United States
| | - Nasib Karl Maluf
- Alliance Protein Laboratories, Inc., San Diego, CA 92121, United States
| | - Susan Krueger
- National Institute of Standards and Technology, Gaithersburg, MD 20899, United States
| | - Garry W Buchko
- Pacific Northwest National Laboratory, Richland, WA 99354, United States
| | - Genyao Lin
- WSP Chemicals & Technology, LLC, Leetsdale, PA 15056, United States
| | - Wendy J Shaw
- Pacific Northwest National Laboratory, Richland, WA 99354, United States
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10
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Katsura KA, Horst JA, Chandra D, Le TQ, Nakano Y, Zhang Y, Horst OV, Zhu L, Le MH, DenBesten PK. WDR72 models of structure and function: a stage-specific regulator of enamel mineralization. Matrix Biol 2014; 38:48-58. [PMID: 25008349 PMCID: PMC4185229 DOI: 10.1016/j.matbio.2014.06.005] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2013] [Revised: 06/21/2014] [Accepted: 06/26/2014] [Indexed: 12/18/2022]
Abstract
Amelogenesis Imperfecta (AI) is a clinical diagnosis that encompasses a group of genetic mutations, each affecting processes involved in tooth enamel formation and thus, result in various enamel defects. The hypomaturation enamel phenotype has been described for mutations involved in the later stage of enamel formation, including Klk4, Mmp20, C4orf26, and Wdr72. Using a candidate gene approach we discovered a novel Wdr72 human mutation in association with AI to be a 5-base pair deletion (c.806_810delGGCAG; p.G255VfsX294). To gain insight into the function of WDR72, we used computer modeling of the full-length human WDR72 protein structure and found that the predicted N-terminal sequence forms two beta-propeller folds with an alpha-solenoid tail at the C-terminus. This domain iteration is characteristic of vesicle coat proteins, such as beta'-COP, suggesting a role for WDR72 in the formation of membrane deformation complexes to regulate intracellular trafficking. Our Wdr72 knockout mouse model (Wdr72(-/-)), containing a LacZ reporter knock-in, exhibited hypomineralized enamel similar to the AI phenotype observed in humans with Wdr72 mutations. MicroCT scans of Wdr72(-/-) mandibles affirmed the hypomineralized enamel phenotype occurring at the onset of the maturation stage. H&E staining revealed a shortened height phenotype in the Wdr72(-/-) ameloblasts with retained proteins in the enamel matrix during maturation stage. H(+)/Cl(-) exchange transporter 5 (CLC5), an early endosome acidifier, was co-localized with WDR72 in maturation-stage ameloblasts and decreased in Wdr72(-/-) maturation-stage ameloblasts. There were no obvious differences in RAB4A and LAMP1 immunostaining of Wdr72(-/-) mice as compared to wildtype controls. Moreover, Wdr72(-/-) ameloblasts had reduced amelogenin immunoreactivity, suggesting defects in amelogenin fragment resorption from the matrix. These data demonstrate that WDR72 has a major role in enamel mineralization, most notably during the maturation stage, and suggest a function involving endocytic vesicle trafficking, possibly in the removal of amelogenin proteins.
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Affiliation(s)
- K A Katsura
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of California, San Francisco, 513 Parnassus Ave., San Francisco, CA 94143-0422, USA
| | - J A Horst
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of California, San Francisco, 513 Parnassus Ave., San Francisco, CA 94143-0422, USA
| | - D Chandra
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of California, San Francisco, 513 Parnassus Ave., San Francisco, CA 94143-0422, USA
| | - T Q Le
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of California, San Francisco, 513 Parnassus Ave., San Francisco, CA 94143-0422, USA
| | - Y Nakano
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of California, San Francisco, 513 Parnassus Ave., San Francisco, CA 94143-0422, USA
| | - Y Zhang
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of California, San Francisco, 513 Parnassus Ave., San Francisco, CA 94143-0422, USA
| | - O V Horst
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of California, San Francisco, 513 Parnassus Ave., San Francisco, CA 94143-0422, USA
| | - L Zhu
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of California, San Francisco, 513 Parnassus Ave., San Francisco, CA 94143-0422, USA
| | - M H Le
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of California, San Francisco, 513 Parnassus Ave., San Francisco, CA 94143-0422, USA
| | - P K DenBesten
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of California, San Francisco, 513 Parnassus Ave., San Francisco, CA 94143-0422, USA
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11
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Wang X, Xing Z, Zhang X, Zhu L, Diekwisch TGH. Alternative Splicing of the Amelogenin Gene in a Caudate Amphibian, Plethodon cinereus. PLoS One 2013; 8:e68965. [PMID: 23840861 PMCID: PMC3694012 DOI: 10.1371/journal.pone.0068965] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2012] [Accepted: 06/09/2013] [Indexed: 11/25/2022] Open
Abstract
As the major enamel matrix protein contributing to tooth development, amelogenin has been demonstrated to play a crucial role in tooth enamel formation. Previous studies have revealed amelogenin alternative splicing as a mechanism for amelogenin heterogeneous expression in mammals. While amelogenin and its splicing forms in mammalian vertebrates have been characterized, splicing variants of amelogenin gene still remains largely unknown in non-mammalian species. Here, using PCR and sequence analysis we discovered two novel amelogenin transcript variants in tooth organ extracts from a caudate amphibian, the salamander Plethodoncinereus. The one was shorter -S- (416 nucleotides including untranslated regions, 5 exons) and the other larger -L- (851 nt, 7 exons) than the previously published “normal” gene in this species -M- (812 nucleotides, 6 exons). This is the first report demonstrating the amelogenin alternative splicing in amphibian, revealing a unique exon 2b and two novel amelogenin gene transcripts in Plethodoncinereus.
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Affiliation(s)
- Xinping Wang
- College of Veterinary Medicine, Jilin University, Changchun, Jilin, China
- * E-mail:
| | - Zeli Xing
- College of Veterinary Medicine, Jilin University, Changchun, Jilin, China
| | - Xichen Zhang
- College of Veterinary Medicine, Jilin University, Changchun, Jilin, China
| | - Lisai Zhu
- College of Veterinary Medicine, Jilin University, Changchun, Jilin, China
| | - Thomas G. H. Diekwisch
- College of Dentistry, University of Illinois at Chicago, Chicago, Illinois, United States of America
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12
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Stahl J, Nakano Y, Kim SO, Gibson CW, Le T, DenBesten P. Leucine rich amelogenin peptide alters ameloblast differentiation in vivo. Matrix Biol 2013; 32:432-42. [PMID: 23747796 DOI: 10.1016/j.matbio.2013.05.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2013] [Revised: 05/27/2013] [Accepted: 05/27/2013] [Indexed: 02/07/2023]
Abstract
Highly mineralized tooth enamel develops from an extracellular matrix chiefly comprised of amelogenins formed by splicing of 7 (human) or 9 (rodent) exons secreted from specialized epithelial cells known as ameloblasts. Here we examined the role of the 59 amino acid alternatively spliced amelogenin known as leucine rich amelogenin peptide (LRAP) on enamel formation, using transgenic murine models in which LRAP overexpression is driven by an amelogenin promoter (TgLRAP). Beginning in the secretory stage of mouse amelogenesis, we found a reduced thickness of enamel matrix and a loss of Tomes' processes, followed by upregulated amelogenin mRNA expression, inhibited amelogenin secretion and loss of cell polarity. In the presecretory stage (P0) amelogenin m180 mRNA expression was increased 58 fold along with a 203 fold increase in MMP-20 expression and 3.5 and 3.2 fold increased in respectively enamelin and ameloblastin. When LRAP was overexpressed on an amelogenin knockout mouse model, the ameloblasts were not affected. Further, expression of the global chromatin organizer and transcription factor SATB1 was reduced in secretory stage TgLRAP ameloblasts. These findings identify a cellular role for LRAP in enamel formation that is not directly related to directing enamel crystal formation as is reported to be the primary function of full length amelogenins. The effect of LRAP overexpression in upregulating amelogenins, MMP-20 and SATB1, suggests a role in protein regulation critical to ameloblast secretion and matrix processing, to form a mineralized enamel matrix.
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Affiliation(s)
- Jonathan Stahl
- Department of Orofacial Sciences, School of Dentistry, University of California, San Francisco, CA, USA
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13
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Hatakeyama Y, Hatakeyama J, Oka K, Tsuruga E, Inai T, Sawa Y. Immunohistochemical Study of Lysosome-Associated Membrane Proteins During Periodontal Ligament Development. J HARD TISSUE BIOL 2013. [DOI: 10.2485/jhtb.22.233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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14
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Feng J, McDaniel JS, Chuang HH, Huang O, Rakian A, Xu X, Steffensen B, Donly KJ, MacDougall M, Chen S. Binding of amelogenin to MMP-9 and their co-expression in developing mouse teeth. J Mol Histol 2012; 43:473-85. [PMID: 22648084 PMCID: PMC3460178 DOI: 10.1007/s10735-012-9423-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2012] [Accepted: 04/29/2012] [Indexed: 12/02/2022]
Abstract
Amelogenin is the most abundant matrix protein in enamel. Proper amelogenin processing by proteinases is necessary for its biological functions during amelogenesis. Matrix metalloproteinase 9 (MMP-9) is responsible for the turnover of matrix components. The relationship between MMP-9 and amelogenin during tooth development remains unknown. We tested the hypothesis that MMP-9 binds to amelogenin and they are co-expressed in ameloblasts during amelogenesis. We evaluated the distribution of both proteins in the mouse teeth using immunohistochemistry and confocal microscopy. At postnatal day 2, the spatial distribution of amelogenin and MMP-9 was co-localized in preameloblasts, secretory ameloblasts, enamel matrix and odontoblasts. At the late stages of mouse tooth development, expression patterns of amelogenin and MMP-9 were similar to that seen in postnatal day 2. Their co-expression was further confirmed by RT-PCR, Western blot and enzymatic zymography analyses in enamel organ epithelial and odontoblast-like cells. Immunoprecipitation assay revealed that MMP-9 binds to amelogenin. The MMP-9 cleavage sites in amelogenin proteins across species were found using bio-informative software program. Analyses of these data suggest that MMP-9 may be involved in controlling amelogenin processing and enamel formation.
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Affiliation(s)
- Junsheng Feng
- Department of Developmental Dentistry, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229-3900, USA
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Huang Y, Goldberg M, Le T, Qiang R, Warner D, Witkowska HE, Liu H, Zhu L, Denbesten P, Li W. Amelogenin exons 8 and 9 encoded peptide enhances leucine rich amelogenin peptide mediated dental pulp repair. Cells Tissues Organs 2012; 196:151-60. [PMID: 22301468 DOI: 10.1159/000331248] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/26/2011] [Indexed: 01/09/2023] Open
Abstract
Amelogenins containing exons 8 and 9 are alternatively spliced variants of amelogenin. Some amelogenin spliced variants have been found to promote pulp regeneration following pulp exposure. The function of the amelogenin spliced variants with the exons 8 and 9 remains unknown. In this study, we synthesized recombinant leucine rich amelogenin peptide (LRAP, A-4), LRAP plus exons 8 and 9 peptide (LRAP 8, 9) or exons 8 and 9 peptide (P89), to determine their effects on odontoblasts. In vivo analyses were completed following the insertion of agarose beads containing LRAP or LRAP 8, 9 into exposed cavity preparations of rat molars. After 8, 15 or 30 days' exposure, the pulp tissues were analyzed for changes in histomorphometry and cell proliferation by PCNA stainings. In vitro analyses included the effects of the addition of the recombinant proteins or peptide on cell proliferation, differentiation and adhesion of postnatal human dental pulp cells (DPCs). These studies showed that in vivo LRAP 8, 9 enhanced the reparative dentin formation as compared to LRAP. In vitro LRAP 8, 9 promoted DPC proliferation and differentiation to a greater extent than LRAP. These data suggest that amelogenin exons 8 and 9 may be useful in amelogenin-mediated pulp repair.
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Affiliation(s)
- Yulei Huang
- Department of Oral Medicine, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, PR China
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Grandin HM, Gemperli AC, Dard M. Enamel matrix derivative: a review of cellular effects in vitro and a model of molecular arrangement and functioning. TISSUE ENGINEERING PART B-REVIEWS 2011; 18:181-202. [PMID: 22070552 DOI: 10.1089/ten.teb.2011.0365] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
BACKGROUND Enamel matrix derivative (EMD), the active component of Emdogain®, is a viable option in the treatment of periodontal disease owing to its ability to regenerate lost tissue. It is believed to mimic odontogenesis, though the details of its functioning remain the focus of current research. OBJECTIVE The aim of this article is to review all relevant literature reporting on the composition/characterization of EMD as well as the effects of EMD, and its components amelogenin and ameloblastin, on the behavior of various cell types in vitro. In this way, insight into the underlying mechanism of regeneration will be garnered and utilized to propose a model for the molecular arrangement and functioning of EMD. METHODS A review of in vitro studies of EMD, or components of EMD, was performed using key words "enamel matrix proteins" OR "EMD" OR "Emdogain" OR "amelogenin" OR "ameloblastin" OR "sheath proteins" AND "cells." Results of this analysis, together with current knowledge on the molecular composition of EMD and the structure and regulation of its components, are then used to present a model of EMD functioning. RESULTS Characterization of the molecular composition of EMD confirmed that amelogenin proteins, including their enzymatically cleaved and alternatively spliced fragments, dominate the protein complex (>90%). A small presence of ameloblastin has also been reported. Analysis of the effects of EMD indicated that gene expression, protein production, proliferation, and differentiation of various cell types are affected and often enhanced by EMD, particularly for periodontal ligament and osteoblastic cell types. EMD also stimulated angiogenesis. In contrast, EMD had a cytostatic effect on epithelial cells. Full-length amelogenin elicited similar effects to EMD, though to a lesser extent. Both the leucine-rich amelogenin peptide and the ameloblastin peptides demonstrated osteogenic effects. A model for molecular structure and functioning of EMD involving nanosphere formation, aggregation, and dissolution is presented. CONCLUSIONS EMD elicits a regenerative response in periodontal tissues that is only partly replicated by amelogenin or ameloblastin components. A synergistic effect among the various proteins and with the cells, as well as a temporal effect, may prove important aspects of the EMD response in vivo.
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Sculean A, Alessandri R, Miron R, Salvi GE, Bosshardt DD. Enamel Matrix Proteins and Periodontal Wound Healing and Regeneration. Clin Adv Periodontics 2011; 1:101-117. [DOI: 10.1902/cap.2011.110047] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2011] [Accepted: 06/14/2011] [Indexed: 12/13/2022]
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He P, Zhang Y, Kim SO, Radlanski RJ, Butcher K, Schneider RA, DenBesten PK. Ameloblast differentiation in the human developing tooth: effects of extracellular matrices. Matrix Biol 2010; 29:411-9. [PMID: 20211728 DOI: 10.1016/j.matbio.2010.03.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2009] [Revised: 02/26/2010] [Accepted: 03/01/2010] [Indexed: 11/25/2022]
Abstract
Tooth enamel is formed by epithelially-derived cells called ameloblasts, while the pulp dentin complex is formed by the dental mesenchyme. These tissues differentiate with reciprocal signaling interactions to form a mature tooth. In this study we have characterized ameloblast differentiation in human developing incisors, and have further investigated the role of extracellular matrix proteins on ameloblast differentiation. Histological and immunohistochemical analyses showed that in the human tooth, the basement membrane separating the early developing dental epithelium and mesenchyme was lost shortly before dentin deposition was initiated, prior to enamel matrix secretion. Presecretary ameloblasts elongated as they came into contact with the dentin matrix, and then shortened to become secretory ameloblasts. In situ hybridization showed that the presecretory stage of odontoblasts started to express type I collagen mRNA, and also briefly expressed amelogenin mRNA. This was followed by upregulation of amelogenin mRNA expression in secretory ameloblasts. In vitro, amelogenin expression was upregulated in ameloblast lineage cells cultured in Matrigel, and was further up-regulated when these cells/Matrigel were co-cultured with dental pulp cells. Co-culture also up-regulated type I collagen expression by the dental pulp cells. Type I collagen coated culture dishes promoted a more elongated ameloblast lineage cell morphology and enhanced cell adhesion via integrin alpha2beta1. Taken together, these results suggest that the basement membrane proteins and signals from underlying mesenchymal cells coordinate to initiate differentiation of preameloblasts and regulate type I collagen expression by odontoblasts. Type I collagen in the dentin matrix then anchors the presecretary ameloblasts as they further differentiate to secretory cells. These studies show the critical roles of the extracellular matrix proteins in ameloblast differentiation.
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Affiliation(s)
- Pingping He
- Department of Orofacial Sciences, University of California-San Francisco, 521 Parnassus Avenue, San Francisco, CA 94143-0640, USA
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Chen J, Zhang Y, Mendoza J, Denbesten P. Calcium-mediated differentiation of ameloblast lineage cells in vitro. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2009; 312B:458-64. [PMID: 19205028 DOI: 10.1002/jez.b.21279] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Calcium is a key component of the mineralized enamel matrix, but may also have a role in ameloblast cell differentiation. In this study we used human ameloblast lineage cells to determine the effect of calcium on cell function. Primary human ameloblast lineage cells were isolated from human fetal tooth buds. Cells were treated with calcium ranging from 0.05 to -1.8 mM. Cell morphology was imaged by phase contrast microscopy, and amelogenin was immunolocalized. Proliferation of cells treated with calcium was measured by BrdU immunoassay. The effect of calcium on mRNA expression of amelogenin, Type 1 collagen, DSPP, amelotin, and KLK-4 was compared by PCR analysis. Von Kossa staining was used to detect mineral formation after cells were pretreated with calcium. Calcium induced cell organization and clustering at 0.1 and 0.3 mM concentrations. Increasing concentrations of calcium significantly reduced ameloblast lineage cell proliferation. The addition of 0.1 mM calcium to the cultures upregulated expression of amelogenin, Type I collagen, and amelotin. After pretreatment with 0.3 mM calcium, the cells could form a mineralized matrix. These studies, which utilized human ameloblast lineage cells grown in vitro, showed that the addition of calcium at 0.1 and 0.3 mM, induced cell differentiation and upregulation of amelogenin Type I collagen and amelotin.
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Affiliation(s)
- James Chen
- Department of Orofacial Sciences, University of California, San Francisco, CA 94143, USA
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Haze A, Taylor AL, Haegewald S, Leiser Y, Shay B, Rosenfeld E, Gruenbaum-Cohen Y, Dafni L, Zimmermann B, Heikinheimo K, Gibson CW, Fisher LW, Young MF, Blumenfeld A, Bernimoulin JP, Deutsch D. Regeneration of bone and periodontal ligament induced by recombinant amelogenin after periodontitis. J Cell Mol Med 2009; 13:1110-24. [PMID: 19228267 PMCID: PMC2889159 DOI: 10.1111/j.1582-4934.2009.00700.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Regeneration of mineralized tissues affected by chronic diseases comprises a major scientific and clinical challenge. Periodontitis, one such prevalent disease, involves destruction of the tooth-supporting tissues, alveolar bone, periodontal-ligament and cementum, often leading to tooth loss. In 1997, it became clear that, in addition to their function in enamel formation, the hydrophobic ectodermal enamel matrix proteins (EMPs) play a role in the regeneration of these periodontal tissues. The epithelial EMPs are a heterogeneous mixture of polypeptides encoded by several genes. It was not clear, however, which of these many EMPs induces the regeneration and what mechanisms are involved. Here we show that a single recombinant human amelogenin protein (rHAM+), induced in vivo regeneration of all tooth-supporting tissues after creation of experimental periodontitis in a dog model. To further understand the regeneration process, amelogenin expression was detected in normal and regenerating cells of the alveolar bone (osteocytes, osteoblasts and osteoclasts), periodontal ligament, cementum and in bone marrow stromal cells. Amelogenin expression was highest in areas of high bone turnover and activity. Further studies showed that during the first 2 weeks after application, rHAM+ induced, directly or indirectly, significant recruitment of mesenchymal progenitor cells, which later differentiated to form the regenerated periodontal tissues. The ability of a single protein to bring about regeneration of all periodontal tissues, in the correct spatio-temporal order, through recruitment of mesenchymal progenitor cells, could pave the way for development of new therapeutic devices for treatment of periodontal, bone and ligament diseases based on rHAM+.
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Affiliation(s)
- Amir Haze
- Institute of Dental Sciences, Hebrew University - Hadassah, Jerusalem, Israel
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Bosshardt DD. Biological mediators and periodontal regeneration: a review of enamel matrix proteins at the cellular and molecular levels. J Clin Periodontol 2008; 35:87-105. [DOI: 10.1111/j.1600-051x.2008.01264.x] [Citation(s) in RCA: 194] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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Goldberg M, Farges JC, Lacerda-Pinheiro S, Six N, Jegat N, Decup F, Septier D, Carrouel F, Durand S, Chaussain-Miller C, Denbesten P, Veis A, Poliard A. Inflammatory and immunological aspects of dental pulp repair. Pharmacol Res 2008; 58:137-47. [PMID: 18602009 PMCID: PMC2853024 DOI: 10.1016/j.phrs.2008.05.013] [Citation(s) in RCA: 157] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2008] [Revised: 05/28/2008] [Accepted: 05/28/2008] [Indexed: 01/09/2023]
Abstract
The repair of dental pulp by direct capping with calcium hydroxide or by implantation of bioactive extracellular matrix (ECM) molecules implies a cascade of four steps: a moderate inflammation, the commitment of adult reserve stem cells, their proliferation and terminal differentiation. The link between the initial inflammation and cell commitment is not yet well established but appears as a potential key factor in the reparative process. Either the release of cytokines due to inflammatory events activates resident stem (progenitor) cells, or inflammatory cells or pulp fibroblasts undergo a phenotypic conversion into osteoblast/odontoblast-like progenitors implicated in reparative dentin formation. Activation of antigen-presenting dendritic cells by mild inflammatory processes may also promote osteoblast/odontoblast-like differentiation and expression of ECM molecules implicated in mineralization. Recognition of bacteria by specific odontoblast and fibroblast membrane receptors triggers an inflammatory and immune response within the pulp tissue that would also modulate the repair process.
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Affiliation(s)
- Michel Goldberg
- Laboratoire de Réparation et Remodelage des Tissus Oro-faciaux, EA 2496, Groupe Matrices Extracellulaires et Biominéralisation, 1 rue Maurice ARNOUX, Faculté de Chirurgie Dentaire, Université Paris-Descartes, 92120 Montrouge, France.
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