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Wen M, Bai Q, Li Y, Li Y, Ma D, Chu J. Morphological study of remineralization of the eroded enamel lesions by tyrosine-rich amelogenin peptide. BMC Oral Health 2024; 24:1054. [PMID: 39252060 PMCID: PMC11384721 DOI: 10.1186/s12903-024-04777-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2024] [Accepted: 08/20/2024] [Indexed: 09/11/2024] Open
Abstract
BACKGROUND Tyrosine-rich amelogenin peptide (TRAP) is the main amelogenin digestion product in the developmental enamel matrix. It has been shown to promote remineralization of demineralized enamel in our previous study. However, direct evidence of the effect of TRAP on the morphology and nanostructure of crystal growth on an enamel surface has not been reported. This study aimed to examine the effect of TRAP on the morphology of calcium phosphate crystals grown on early enamel erosion using a pH-cycling model. METHODS Eroded lesions were produced in human premolars by 30-second immersion in 37% phosphoric acid. Forty-five samples of eroded human premolar enamel blocks were selected and randomly divided into 3 groups: deionized water (DDW, negative control); 100 µg/mL TRAP, and 2 ppm sodium fluoride (NaF, positive control group). For 14 days, the specimens were exposed to a pH-cycling model. Using scanning electron microscopy (SEM) and atomic force microscopy (AFM) methods, the surface morphology, calcium-phosphorus ratio, and enamel surface roughness were examined. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) were used to assess crystal characteristics. RESULTS After pH-cycling, compared to the two control groups, the surface of the eroded enamel of the peptide TRAP group shows a large number of new, densely arranged rod-like crystals, parallel to each other, regularly arranged, forming an ordered structure, with crystal morphology similar to that of natural enamel. The crystals are mostly hydroxyapatite (HA). CONCLUSION This study demonstrates that the peptide TRAP modulates the formation of hydroxyapatite in eroded enamel and that the newly formed crystals resemble natural enamel crystals and promote the remineralization of enamel, providing a promising biomaterial for remineralization treatment of enamel lesions.
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Affiliation(s)
- Mingzhu Wen
- The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Qinghua Bai
- The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Yiwei Li
- The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Yaru Li
- The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Dandan Ma
- The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Jinpu Chu
- The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China.
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2
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Gabe CM, Bui AT, Lukashova L, Verdelis K, Vasquez B, Beniash E, Margolis HC. Role of amelogenin phosphorylation in regulating dental enamel formation. Matrix Biol 2024; 131:17-29. [PMID: 38759902 PMCID: PMC11363587 DOI: 10.1016/j.matbio.2024.05.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Revised: 05/08/2024] [Accepted: 05/14/2024] [Indexed: 05/19/2024]
Abstract
Amelogenin (AMELX), the predominant matrix protein in enamel formation, contains a singular phosphorylation site at Serine 16 (S16) that greatly enhances AMELX's capacity to stabilize amorphous calcium phosphate (ACP) and inhibit its transformation to apatitic enamel crystals. To explore the potential role of AMELX phosphorylation in vivo, we developed a knock-in (KI) mouse model in which AMELX phosphorylation is prevented by substituting S16 with Ala (A). As anticipated, AMELXS16A KI mice displayed a severe phenotype characterized by weak hypoplastic enamel, absence of enamel rods, extensive ectopic calcifications, a greater rate of ACP transformation to apatitic crystals, and progressive cell pathology in enamel-forming cells (ameloblasts). In the present investigation, our focus was on understanding the mechanisms of action of phosphorylated AMELX in amelogenesis. We have hypothesized that the absence of AMELX phosphorylation would result in a loss of controlled mineralization during the secretory stage of amelogenesis, leading to an enhanced rate of enamel mineralization that causes enamel acidification due to excessive proton release. To test these hypotheses, we employed microcomputed tomography (µCT), colorimetric pH assessment, and Fourier Transform Infrared (FTIR) microspectroscopy of apical portions of mandibular incisors from 8-week old wildtype (WT) and KI mice. As hypothesized, µCT analyses demonstrated significantly higher rates of enamel mineral densification in KI mice during the secretory stage compared to the WT. Despite a greater rate of enamel densification, maximal KI enamel thickness increased at a significantly lower rate than that of the WT during the secretory stage of amelogenesis, reaching a thickness in mid-maturation that is approximately half that of the WT. pH assessments revealed a lower pH in secretory enamel in KI compared to WT mice, as hypothesized. FTIR findings further demonstrated that KI enamel is comprised of significantly greater amounts of acid phosphate compared to the WT, consistent with our pH assessments. Furthermore, FTIR microspectroscopy indicated a significantly higher mineral-to-organic ratio in KI enamel, as supported by µCT findings. Collectively, our current findings demonstrate that phosphorylated AMELX plays crucial mechanistic roles in regulating the rate of enamel mineral formation, and in maintaining physico-chemical homeostasis and the enamel growth pattern during early stages of amelogenesis.
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Affiliation(s)
- Claire M Gabe
- Department of Oral and Craniofacial Sciences, University of Pittsburgh School of Dental Medicine, 335 Sutherland Drive (UPSDM), Pittsburgh, PA 15260, USA; Center for Craniofacial Regeneration, UPSDM, Pittsburgh, PA, USA
| | - Ai Thu Bui
- Department of Oral and Craniofacial Sciences, University of Pittsburgh School of Dental Medicine, 335 Sutherland Drive (UPSDM), Pittsburgh, PA 15260, USA; Center for Craniofacial Regeneration, UPSDM, Pittsburgh, PA, USA
| | | | - Kostas Verdelis
- Center for Craniofacial Regeneration, UPSDM, Pittsburgh, PA, USA; Department of Endodontics, UPSDM, Pittsburgh, PA, USA
| | - Brent Vasquez
- Department of Oral and Craniofacial Sciences, University of Pittsburgh School of Dental Medicine, 335 Sutherland Drive (UPSDM), Pittsburgh, PA 15260, USA; Center for Craniofacial Regeneration, UPSDM, Pittsburgh, PA, USA
| | - Elia Beniash
- Department of Oral and Craniofacial Sciences, University of Pittsburgh School of Dental Medicine, 335 Sutherland Drive (UPSDM), Pittsburgh, PA 15260, USA; Center for Craniofacial Regeneration, UPSDM, Pittsburgh, PA, USA
| | - Henry C Margolis
- Department of Oral and Craniofacial Sciences, University of Pittsburgh School of Dental Medicine, 335 Sutherland Drive (UPSDM), Pittsburgh, PA 15260, USA; Center for Craniofacial Regeneration, UPSDM, Pittsburgh, PA, USA; Department of Periodontics and Preventive Dentistry, UPSDM, Pittsburgh, PA, USA.
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3
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Kegulian NC, Visakan G, Bapat RA, Moradian-Oldak J. Ameloblastin and its multifunctionality in amelogenesis: A review. Matrix Biol 2024; 131:62-76. [PMID: 38815936 PMCID: PMC11218920 DOI: 10.1016/j.matbio.2024.05.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2024] [Revised: 05/16/2024] [Accepted: 05/24/2024] [Indexed: 06/01/2024]
Abstract
Extracellular matrix proteins play crucial roles in the formation of mineralized tissues like bone and teeth via multifunctional mechanisms. In tooth enamel, ameloblastin (Ambn) is one such multifunctional extracellular matrix protein implicated in cell signaling and polarity, cell adhesion to the developing enamel matrix, and stabilization of prismatic enamel morphology. To provide a perspective for Ambn structure and function, we begin this review by describing dental enamel and enamel formation (amelogenesis) followed by a description of enamel extracellular matrix. We then summarize the established domains and motifs in Ambn protein, human amelogenesis imperfecta cases, and genetically engineered mouse models involving mutated or null Ambn. We subsequently delineate in silico, in vitro, and in vivo evidence for the amphipathic helix in Ambn as a proposed cell-matrix adhesive and then more recent in vitro evidence for the multitargeting domain as the basis for dynamic interactions of Ambn with itself, amelogenin, and membranes. The multitargeting domain facilitates tuning between Ambn-membrane interactions and self/co-assembly and supports a likely overall role for Ambn as a matricellular protein. We anticipate that this review will enhance the understanding of multifunctional matrix proteins by consolidating diverse mechanisms through which Ambn contributes to enamel extracellular matrix mineralization.
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Affiliation(s)
- Natalie C Kegulian
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, 2250 Alcazar St., CSA 148, Los Angeles, CA 90033, USA
| | - Gayathri Visakan
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, 2250 Alcazar St., CSA 148, Los Angeles, CA 90033, USA
| | - Rucha Arun Bapat
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, 2250 Alcazar St., CSA 148, Los Angeles, CA 90033, USA
| | - Janet Moradian-Oldak
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, 2250 Alcazar St., CSA 148, Los Angeles, CA 90033, USA.
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4
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Buchko GW, Zhou M, Vesely CH, Tao J, Shaw WJ, Mehl RA, Cooley RB. High-yield recombinant bacterial expression of 13 C-, 15 N-labeled, serine-16 phosphorylated, murine amelogenin using a modified third generation genetic code expansion protocol. Protein Sci 2023; 32:e4560. [PMID: 36585836 PMCID: PMC9850436 DOI: 10.1002/pro.4560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 12/21/2022] [Accepted: 12/29/2022] [Indexed: 01/01/2023]
Abstract
Amelogenin constitutes ~90% of the enamel matrix in the secretory stage of amelogenesis, a still poorly understood process that results in the formation of the hardest and most mineralized tissue in vertebrates-enamel. Most biophysical research with amelogenin uses recombinant protein expressed in Escherichia coli. In addition to providing copious amounts of protein, recombinant expression allows 13 C- and 15 N-labeling for detailed structural studies using NMR spectroscopy. However, native amelogenin is phosphorylated at one position, Ser-16 in murine amelogenin, and there is mounting evidence that Ser-16 phosphorylation is important. Using a modified genetic code expansion protocol we have expressed and purified uniformly 13 C-, 15 N-labeled murine amelogenin (pS16M179) with ~95% of the protein being correctly phosphorylated. Homogeneous phosphorylation was achieved using commercially available, enriched, 13 C-, 15 N-labeled media, and protein expression was induced with isopropyl β-D-1-thiogalactopyranoside at 310 K. Phosphoserine incorporation was verified from one-dimensional 31 P NMR spectra, comparison of 1 H-15 N HSQC spectra, Phos-tag SDS PAGE, and mass spectrometry. Phosphorus-31 NMR spectra for pS16M179 under conditions known to trigger amelogenin self-assembly into nanospheres confirm nanosphere models with buried N-termini. Lambda phosphatase treatment of these nanospheres results in the dephosphorylation of pS16M179, confirming that smaller oligomers and monomers with exposed N-termini are in equilibrium with nanospheres. Such 13 C-, 15 N-labeling of amelogenin with accurately encoded phosphoserine incorporation will accelerate biomineralization research to understand amelogenesis and stimulate the expanded use of genetic code expansion protocols to introduce phosphorylated amino acids into proteins.
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Affiliation(s)
- Garry W. Buchko
- Earth and Biological Sciences DirectoratePacific Northwest National LaboratoryRichlandWashingtonUSA,School of Molecular BiosciencesWashington State UniversityPullmanWashingtonUSA
| | - Mowei Zhou
- Earth and Biological Sciences DirectoratePacific Northwest National LaboratoryRichlandWashingtonUSA
| | - Cat Hoang Vesely
- Department of Biochemistry and BiophysicsOregon State UniversityCorvallisOregonUSA
| | - Jinhui Tao
- Physical and Computational Sciences DirectoratePacific Northwest National LaboratoryRichlandWashingtonUSA
| | - Wendy J. Shaw
- Physical and Computational Sciences DirectoratePacific Northwest National LaboratoryRichlandWashingtonUSA
| | - Ryan A. Mehl
- Department of Biochemistry and BiophysicsOregon State UniversityCorvallisOregonUSA
| | - Richard B. Cooley
- Department of Biochemistry and BiophysicsOregon State UniversityCorvallisOregonUSA
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5
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Buchko GW, Mergelsberg ST, Tarasevich BJ, Shaw WJ. Residue-Specific Insights into the Intermolecular Protein–Protein Interfaces Driving Amelogenin Self-Assembly in Solution. Biochemistry 2022; 61:2909-2921. [DOI: 10.1021/acs.biochem.2c00522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Affiliation(s)
- Garry W. Buchko
- Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
- School of Molecular Biosciences, Washington State University, Pullman, Washington 99164, United States
| | - Sebastian T. Mergelsberg
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Barbara J. Tarasevich
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Wendy J. Shaw
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
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6
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Tao J, Hanson E, Dohnalkova AC, Buchko GW, Jin B, Shaw WJ, Tarasevich BJ. Changes in the C-terminal, N-terminal, and histidine regions of amelogenin reveal the role of oligomer quaternary structure on adsorption and hydroxyapatite mineralization. Front Physiol 2022; 13:1034662. [PMID: 36523551 PMCID: PMC9746691 DOI: 10.3389/fphys.2022.1034662] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Accepted: 11/14/2022] [Indexed: 10/29/2023] Open
Abstract
Adsorption interactions between amelogenin and calcium phosphate minerals are believed to be important to amelogenin's function in enamel formation, however, the role of specific amino acid residues and domains within the protein in controlling adsorption is not well known. We synthesized "mechanistic probes" by systematically removing charged regions of amelogenin in order to elucidate their roles. The probes included amelogenin without the charged residues in the N-terminus (SEKR), without two, three, or eight histidines (H) in the central protein region (H2, H3, H8), or without the C-terminal residues (Delta). In-situ atomic force microscopy (AFM) adsorption studies onto hydroxyapatite (HAP) single crystals confirmed that the C-terminus was the dominant domain in promoting adsorption. We propose that subtle changes in protein-protein interactions for proteins with histidines and N-terminal residues removed resulted in changes in the oligomer quaternary size and structure that also affected protein adsorption. HAP mineralization studies revealed that the oligomer-HAP binding energy and protein layer thickness were factors in controlling the amorphous calcium phosphate (ACP) to HAP induction time. Our studies with mechanistic probes reveal the importance of the oligomer quaternary structure in controlling amelogenin adsorption and HAP mineralization.
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Affiliation(s)
- Jinhui Tao
- Pacific Northwest National Laboratory, Richland, WA, United States
| | - Emma Hanson
- Pacific Northwest National Laboratory, Richland, WA, United States
| | | | - Garry W. Buchko
- Pacific Northwest National Laboratory, Richland, WA, United States
- School of Molecular Biosciences, Washington State University, Pullman, WA, United States
| | - Biao Jin
- Pacific Northwest National Laboratory, Richland, WA, United States
| | - Wendy J. Shaw
- Pacific Northwest National Laboratory, Richland, WA, United States
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7
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Santra M, Liu YC, Jhanji V, Yam GHF. Human SMILE-Derived Stromal Lenticule Scaffold for Regenerative Therapy: Review and Perspectives. Int J Mol Sci 2022; 23:ijms23147967. [PMID: 35887309 PMCID: PMC9315730 DOI: 10.3390/ijms23147967] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 07/10/2022] [Accepted: 07/18/2022] [Indexed: 12/13/2022] Open
Abstract
A transparent cornea is paramount for vision. Corneal opacity is one of the leading causes of blindness. Although conventional corneal transplantation has been successful in recovering patients’ vision, the outcomes are challenged by a global lack of donor tissue availability. Bioengineered corneal tissues are gaining momentum as a new source for corneal wound healing and scar management. Extracellular matrix (ECM)-scaffold-based engineering offers a new perspective on corneal regenerative medicine. Ultrathin stromal laminar tissues obtained from lenticule-based refractive correction procedures, such as SMall Incision Lenticule Extraction (SMILE), are an accessible and novel source of collagen-rich ECM scaffolds with high mechanical strength, biocompatibility, and transparency. After customization (including decellularization), these lenticules can serve as an acellular scaffold niche to repopulate cells, including stromal keratocytes and stem cells, with functional phenotypes. The intrastromal transplantation of these cell/tissue composites can regenerate native-like corneal stromal tissue and restore corneal transparency. This review highlights the current status of ECM-scaffold-based engineering with cells, along with the development of drug and growth factor delivery systems, and elucidates the potential uses of stromal lenticule scaffolds in regenerative therapeutics.
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Affiliation(s)
- Mithun Santra
- Corneal Regeneration Laboratory, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA; (M.S.); (V.J.)
| | - Yu-Chi Liu
- Tissue Engineering and Cell Therapy Group, Singapore Eye Research Institute, Singapore 169856, Singapore;
- Ophthalmology and Visual Sciences Academic Clinical Program, Duke-NUS Medical School, Singapore 169857, Singapore
| | - Vishal Jhanji
- Corneal Regeneration Laboratory, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA; (M.S.); (V.J.)
| | - Gary Hin-Fai Yam
- Corneal Regeneration Laboratory, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA; (M.S.); (V.J.)
- Tissue Engineering and Cell Therapy Group, Singapore Eye Research Institute, Singapore 169856, Singapore;
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA
- Correspondence:
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8
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Peng X, Han S, Wang K, Ding L, Liu Z, Zhang L. The Amelogenin-Derived Peptide TVH-19 Promotes Dentinal Tubule Occlusion and Mineralization. Polymers (Basel) 2021; 13:2473. [PMID: 34372076 PMCID: PMC8347252 DOI: 10.3390/polym13152473] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 07/18/2021] [Accepted: 07/23/2021] [Indexed: 12/12/2022] Open
Abstract
In this study, the amelogenin-derived peptide, TVH-19, which has been confirmed to promote mineralization, was evaluated to derive its potential to induce dentinal tubule occlusion. The binding capability of fluorescein isothiocyanate (FITC)-labeled TVH-19 to the demineralized dentin surface was analyzed by confocal laser scanning microscopy (CLSM). Additionally, the sealing function of the peptide was studied through the remineralization of demineralized dentin in vitro. The adsorption results showed that TVH-19 could bind to the hydroxyapatite and demineralized dentin surfaces, especially to periodontal dentin. Scanning electron microscopy analysis further revealed that TVH-19 created mineral precipitates. The plugging rate in the TVH-19 group was higher than that in the PBS group. Moreover, energy-dispersive X-ray spectroscopy (EDX) results indicated that the calcium/phosphorus (Ca/P) ratio of the new minerals induced by TVH-19 was close to that of the hydroxyapatite. Attenuated total internal reflection-Fourier transform infrared (ATR-FTIR) spectrometry and X-ray diffraction (XRD) results indicated that the hydroxyapatite crystals formed via remineralization elongated the axial growth and closely resembled the natural dentin components. These findings indicate that TVH-19 can effectively promote dentin sealing by binding to the periodontal dentin, promoting mineral deposition, and reducing the space between the dentin tubules.
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Affiliation(s)
| | | | | | | | | | - Linglin Zhang
- State Key Laboratory of Oral Diseases, National Clinical Research Centre for Oral Disease, Sichuan University, Chengdu 610041, China; (X.P.); (S.H.); (K.W.); (L.D.); (Z.L.)
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9
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Geng S, Lei Y, Snead ML. Minimal amelogenin domain for enamel formation. JOM (WARRENDALE, PA. : 1989) 2021; 73:1696-1704. [PMID: 34456537 PMCID: PMC8386916 DOI: 10.1007/s11837-021-04687-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Accepted: 03/31/2021] [Indexed: 06/13/2023]
Abstract
Amelogenin is the most abundant matrix protein guiding hydroxyapatite formation in enamel, the durable bioceramic tissue that covers vertebrate teeth. Here, we sought to refine structure-function for an amelogenin domain based on in vitro data showing a 42 amino acid amelogenin-derived peptide (ADP7) mimicked formation of hydroxyapatite similar to that observed for the full-length mouse 180 amino acid protein. In mice, we used CRISPR-Cas9 to express only ADP7 by the native amelogenin promoter. Analysis revealed ADP7 messenger RNA expression in developing mouse teeth with the formation of a thin layer of enamel. In vivo, ADP7 peptide partially replaced the function of the full-length amelogenin protein and its several protein isoforms. Protein structure-function relationships identified through in vitro assays can be deployed in whole model animals using CRISPR-Cas9 to validate function of a minimal protein domain to be translated for clinical use as an enamel biomimetic.
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Affiliation(s)
- Shuhui Geng
- The University of Southern California, Herman Ostrow School of Dentistry of USC, Center for Craniofacial Molecular Biology, Los Angeles, CA 90033
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China, 201210
| | - Yaping Lei
- The University of Southern California, Herman Ostrow School of Dentistry of USC, Center for Craniofacial Molecular Biology, Los Angeles, CA 90033
- Biology and Biologic Engineering, California Institute of Technology, Pasadena, CA 91125
| | - Malcolm L Snead
- The University of Southern California, Herman Ostrow School of Dentistry of USC, Center for Craniofacial Molecular Biology, Los Angeles, CA 90033
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10
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Bapat RA, Su J, Moradian-Oldak J. Co-Immunoprecipitation Reveals Interactions Between Amelogenin and Ameloblastin via Their Self-Assembly Domains. Front Physiol 2020; 11:622086. [PMID: 33424645 PMCID: PMC7786100 DOI: 10.3389/fphys.2020.622086] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 12/04/2020] [Indexed: 01/28/2023] Open
Abstract
Macromolecular assembly of extracellular enamel matrix proteins (EMPs) is intimately associated with the nucleation, growth, and maturation of highly organized hydroxyapatite crystals giving rise to healthy dental enamel. Although the colocalization of two of the most abundant EMPs amelogenin (Amel) and ameloblastin (Ambn) in molar enamel has been established, the evidence toward their interaction is scarce. We used co-immunoprecipitation (co-IP) to show evidence of direct molecular interactions between recombinant and native Amel and Ambn. Ambn fragments containing Y/F-x-x-Y/L/F-x-Y/F self-assembly motif were isolated from the co-IP column and characterized by mass spectroscopy. We used recombinant Ambn (rAmbn) mutants with deletion of exons 5 and 6 as well as Ambn derived synthetic peptides to demonstrate that Ambn binds to Amel via its previously identified Y/F-x-x-Y/L/F-x-Y/F self-assembly motif at the N-terminus of its exon 5 encoded region. Using an N-terminal specific anti-Ambn antibody, we showed that Ambn N-terminal fragments colocalized with Amel from secretory to maturation stages of enamel formation in a single section of developing mouse incisor, and closely followed mineral patterns in enamel rod interrod architecture. We conclude that Ambn self-assembly motif is involved in its interaction with Amel in solution and that colocalization between the two proteins persists from secretory to maturation stages of amelogenesis. Our in vitro and in situ data support the notion that Amel and Ambn may form heteromolecular assemblies that may perform important physiological roles during enamel formation.
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Affiliation(s)
| | | | - Janet Moradian-Oldak
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, CA, United States
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11
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Characterization of AMBN I and II Isoforms and Study of Their Ca 2+-Binding Properties. Int J Mol Sci 2020; 21:ijms21239293. [PMID: 33291486 PMCID: PMC7730623 DOI: 10.3390/ijms21239293] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 12/02/2020] [Accepted: 12/03/2020] [Indexed: 01/29/2023] Open
Abstract
Ameloblastin (Ambn) as an intrinsically disordered protein (IDP) stands for an important role in the formation of enamel—the hardest biomineralized tissue commonly formed in vertebrates. The human ameloblastin (AMBN) is expressed in two isoforms: full-length isoform I (AMBN ISO I) and isoform II (AMBN ISO II), which is about 15 amino acid residues shorter than AMBN ISO I. The significant feature of AMBN—its oligomerization ability—is enabled due to a specific sequence encoded by exon 5 present at the N-terminal part in both known isoforms. In this study, we characterized AMBN ISO I and AMBN ISO II by biochemical and biophysical methods to determine their common features and differences. We confirmed that both AMBN ISO I and AMBN ISO II form oligomers in in vitro conditions. Due to an important role of AMBN in biomineralization, we further addressed the calcium (Ca2+)-binding properties of AMBN ISO I and ISO II. The binding properties of AMBN to Ca2+ may explain the role of AMBN in biomineralization and more generally in Ca2+ homeostasis processes.
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12
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Sequence characteristics responsible for protein‐protein interactions in the intrinsically disordered regions of caseins, amelogenins, and small heat‐shock proteins. Biopolymers 2019; 110:e23319. [DOI: 10.1002/bip.23319] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Revised: 06/11/2019] [Accepted: 06/19/2019] [Indexed: 01/01/2023]
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13
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Mechanics of amelogenin TRAP protein in the proximity of hydroxyapatite mineral is altered by interfacial water. Chem Phys 2019. [DOI: 10.1016/j.chemphys.2019.02.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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14
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Wang X, Wang Y, Wang K, Ren Q, Li H, Zheng S, Niu Y, Zhou X, Li W, Zhang L. Bifunctional anticaries peptides with antibacterial and remineralizing effects. Oral Dis 2018; 25:488-496. [PMID: 30291730 DOI: 10.1111/odi.12990] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Revised: 09/17/2018] [Accepted: 09/28/2018] [Indexed: 02/05/2023]
Affiliation(s)
- Xiuqing Wang
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & Department of Cariology and Endodontics; West China Hospital of Stomatology, Sichuan University; Chengdu China
- Department of Endodontics and Operative Dentistry, School and Hospital of Stomatology; Fujian Medical University; Fuzhou China
| | - Yufei Wang
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & Department of Cariology and Endodontics; West China Hospital of Stomatology, Sichuan University; Chengdu China
| | - Kun Wang
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & Department of Cariology and Endodontics; West China Hospital of Stomatology, Sichuan University; Chengdu China
| | - Qian Ren
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & Department of Cariology and Endodontics; West China Hospital of Stomatology, Sichuan University; Chengdu China
| | - Haoran Li
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & Department of Cariology and Endodontics; West China Hospital of Stomatology, Sichuan University; Chengdu China
| | - Sainan Zheng
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & Department of Cariology and Endodontics; West China Hospital of Stomatology, Sichuan University; Chengdu China
| | - Yumei Niu
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & Department of Cariology and Endodontics; West China Hospital of Stomatology, Sichuan University; Chengdu China
| | - Xuedong Zhou
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & Department of Cariology and Endodontics; West China Hospital of Stomatology, Sichuan University; Chengdu China
| | - Wei Li
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & Department of Cariology and Endodontics; West China Hospital of Stomatology, Sichuan University; Chengdu China
| | - Linglin Zhang
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & Department of Cariology and Endodontics; West China Hospital of Stomatology, Sichuan University; Chengdu China
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15
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Al-Jawad M, Addison O, Sirovica S, Siddiqui S, Martin RA, Wood DJ, Watts DC. Intracoronal stress transfer through enamel following RBC photopolymerisation: A synchrotron X-ray study. Dent Mater 2018; 34:1426-1439. [PMID: 30119841 DOI: 10.1016/j.dental.2018.07.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 07/29/2018] [Accepted: 07/29/2018] [Indexed: 11/28/2022]
Abstract
OBJECTIVES To measure the spatial distribution of crystallographic strain in tooth enamel induced by the photo-polymerisation of a dimethacrylate resin based composite cavity restoration. METHODS Six sound first premolar teeth, allocated into two groups (n=3), were prepared with mesio-occlusal distal cavities. The enamel was machined at the point of maximum convexity on the outer tooth to create a vertical fin of thickness 100μm and 0.5mm depth to allow for synchrotron X-ray diffraction measurements. 2D diffraction patterns were used to determine crystallite orientation and quantify changes in the hydroxyapatite crystal lattice parameters, before and after photo-polymerisation of a composite material placed in the cavity, to calculate strain in the respective axis. The composite was photo-polymerised with either relatively high (1200mWcm-2, group 1) or low (480mWcm-2, group 2) irradiances using LED or quartz halogen light sources, respectively. A paired t-test was used to determine significant differences in strain between irradiance protocols at ɑ=0.001. RESULTS Photo-polymerisation of the composite in the adjacent cavity induced significant changes in both the crystallographic c and a axes of the enamel measurement area. However the magnitude of strain was low with ∼0.1% difference before and after composite photo-polymerisation. Strain in enamel was not uniformly distributed and varied spatially as a function of crystallite orientation. Increased alignment of crystallites perpendicular to the cavity wall was associated with higher c axis strain. Additionally, strain was significantly greater in the c (p<0.001) and a axis (p<0.001) when using a high irradiance photo-polymerisation protocol. SIGNIFICANCE Although cuspal deflection is routinely measured to indirectly assess the 'global' effect of composite shrinkage on the tooth-restoration complex, here we show that absolute strains generated in enamel are low, indicating strain relief mechanisms may be operative. The use of low irradiance protocols for photo-polymerisation resulted in reduced strain.
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Affiliation(s)
- Maisoon Al-Jawad
- Institute of Dentistry, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK.
| | - Owen Addison
- Biomaterials Unit, University of Birmingham School of Dentistry, Birmingham, UK; University of Alberta, School of Dentistry, Edmonton, AB, Canada.
| | - Slobodan Sirovica
- University of Alberta, School of Dentistry, Edmonton, AB, Canada; Aston Institute of Materials Research, Aston University, Birmingham, UK
| | - Samera Siddiqui
- Institute of Dentistry, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Richard A Martin
- Aston Institute of Materials Research, Aston University, Birmingham, UK
| | - David J Wood
- Biomaterials and Tissue Engineering Research Group, School of Dentistry, University of Leeds, Leeds, UK
| | - David C Watts
- School of Medical Sciences and Photon Science Institute, University of Manchester, UK
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16
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Chu J, Feng X, Guo H, Zhang T, Zhao H, Zhang Q. Remineralization Efficacy of an Amelogenin-Based Synthetic Peptide on Carious Lesions. Front Physiol 2018; 9:842. [PMID: 30026702 PMCID: PMC6041723 DOI: 10.3389/fphys.2018.00842] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 06/14/2018] [Indexed: 11/13/2022] Open
Abstract
Objective: The aim of this study was to evaluate the remineralization efficacy of an amelogenin-based peptide on initial enamel carious lesions in vitro. Furthermore, we attempted to provide insights into the possible mechanism of the remineralization, including determining the calcium-binding properties of the peptide and its effects on calcium phosphate mineralization. Methods: The peptide comprising the N-terminus and the C-terminus of porcine amelogenin was synthesized by Synpeptide Co., Ltd. Fifty specimens were randomly assigned to five immersing treatment groups for 12 days: remineralizing medium only; 12.5 μg/mL peptide + remineralizing medium; 25 μg/mL peptide + remineralizing medium; 50 μg/mL peptide + remineralizing medium; fluoride + remineralizing medium. After immersion, mean mineral loss before and after remineralization of each specimen was determined using micro-CT. Mean mineral gain after remineralization was calculated. Calcium binding properties were measured by Isothermal titration calorimetry (ITC). TEM and Fourier transform-infrared were used to determine the effects of the peptide on calcium phosphate mineralization. Results: A significant decrease in mineral loss after remineralization process in all groups was observed (p < 0.05). Treatment in remineralizing medium resulted in the lowest mineral gain while the fluoridated treatment exhibited the highest mineral gain among all groups. Inclusion of synthetic peptide in the remineralizing medium exhibited a higher mineral gain and the gain of 50 μg/mL group was greater than that of the 25 μg/mL group. No significant difference in mineral gain was observed between the remineralizing medium only group and the 12.5 μg/mL peptide group (p > 0.05). ITC values showed that the Ca2+-binding affinity of the peptide is about 9.914 × 104M−1. Furthermore, the peptide was found to inhibit calcium phosphate precipitation and stabilize amorphous calcium phosphate formation for more than 2 h and finally transform into ordered hydroxyapatite crystals. Conclusion: Specific concentrations of the amelogenin-based synthetic peptide promoted in vitro remineralization, with higher concentrations exhibiting significantly greater remineralization. This study presented evidence suggesting that the peptide may act as a Ca2+carrier as well as a regulating factor. When the stabilizing calcium and phosphorus ions bind with the peptide they become biologically available for the remineralization of deeper carious lesions, while also regulated by the peptide to transform into ordered hydroxyapatite crystals.
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Affiliation(s)
- Jinpu Chu
- The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Xiaofang Feng
- The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China.,College of Stomatology, Zhengzhou University, Zhengzhou, China
| | - Huijing Guo
- The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Tieting Zhang
- The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Hualei Zhao
- The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China.,College of Stomatology, Zhengzhou University, Zhengzhou, China
| | - Qun Zhang
- The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China.,College of Stomatology, Zhengzhou University, Zhengzhou, China
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17
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Rathsam C, Farahani RM, Hains PG, Valova VA, Charadram N, Zoellner H, Swain M, Hunter N. Characterization of inter-crystallite peptides in human enamel rods reveals contribution by the Y allele of amelogenin. J Struct Biol 2018; 204:26-37. [PMID: 29959991 DOI: 10.1016/j.jsb.2018.06.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Revised: 06/19/2018] [Accepted: 06/21/2018] [Indexed: 11/18/2022]
Abstract
Proteins of the inter-rod sheath and peptides within the narrow inter-crystallite space of the rod structure are considered largely responsible for visco-elastic and visco-plastic properties of enamel. The present study was designed to investigate putative peptides of the inter-crystallite space. Entities of 1-6 kDa extracted from enamel rods of erupted permanent teeth were analysed by mass spectrometry (MS) and shown to comprise N-terminal amelogenin (AMEL) peptides either containing or not containing exon 4 product. Other dominant entities consisted of an N-terminal peptide from ameloblastin (AMBN) and a series of the most hydrophobic peptides from serum albumin (ALBN). Amelogenin peptides encoded by the Y-chromosome allele were strongly detected in Enamel from male teeth. Location of N-terminal AMEL peptides as well as AMBN and ALBN, between apatite crystallites, was disclosed by immunogold scanning electron microscopy (SEM). Density plots confirmed the relative abundance of these products including exon 4+ AMEL peptides that have greater capacity for binding to hydroxyapatite. Hydrophilic X and Y peptides encoded in exon 4 differ only in substitution of non-polar isoleucine in Y for polar threonine in X with reduced disruption of the hydrophobic N-terminal structure in the Y form. Despite similarity of X and Y alleles of AMEL the non-coding region upstream from exon 4 shows significant variation with implications for segregation of processing of transcripts from exon 4. Detection of fragments from multiple additional proteins including keratins (KER), fetuin A (FETUA), proteinases and proteinase inhibitors, likely reflect biochemical events during enamel formation.
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Affiliation(s)
- Catherine Rathsam
- Institute of Dental Research, Westmead Institute for Medical Research and Centre for Oral Health, Westmead, New South Wales, Australia.
| | - Ramin M Farahani
- Institute of Dental Research, Westmead Institute for Medical Research and Centre for Oral Health, Westmead, New South Wales, Australia; Faculty of Dentistry, The University of Sydney, New South Wales, Australia
| | - Peter G Hains
- Children's Medical Research Institute, The University of Sydney, Westmead, New South Wales, Australia
| | - Valentina A Valova
- Children's Medical Research Institute, The University of Sydney, Westmead, New South Wales, Australia
| | - Nattida Charadram
- Institute of Dental Research, Westmead Institute for Medical Research and Centre for Oral Health, Westmead, New South Wales, Australia; Faculty of Dentistry, The University of Sydney, New South Wales, Australia
| | - Hans Zoellner
- Faculty of Dentistry, The University of Sydney, New South Wales, Australia
| | - Michael Swain
- Faculty of Dentistry, The University of Sydney, New South Wales, Australia; Faculty of Dentistry, Kuwait University, Kuwait
| | - Neil Hunter
- Institute of Dental Research, Westmead Institute for Medical Research and Centre for Oral Health, Westmead, New South Wales, Australia; Faculty of Dentistry, The University of Sydney, New South Wales, Australia
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18
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Brown N, Lei J, Zhan C, Shimon LJW, Adler-Abramovich L, Wei G, Gazit E. Structural Polymorphism in a Self-Assembled Tri-Aromatic Peptide System. ACS NANO 2018; 12:3253-3262. [PMID: 29558116 PMCID: PMC6333291 DOI: 10.1021/acsnano.7b07723] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Self-assembly is a process of key importance in natural systems and in nanotechnology. Peptides are attractive building blocks due to their relative facile synthesis, biocompatibility, and other unique properties. Diphenylalanine (FF) and its derivatives are known to form nanostructures of various architectures and interesting and varied characteristics. The larger triphenylalanine peptide (FFF) was found to self-assemble as efficiently as FF, forming related but distinct architectures of plate-like and spherical nanostructures. Here, to understand the effect of triaromatic systems on the self-assembly process, we examined carboxybenzyl-protected diphenylalanine (z-FF) as a minimal model for such an arrangement. We explored different self-assembly conditions by changing solvent compositions and peptide concentrations, generating a phase diagram for the assemblies. We discovered that z-FF can form a variety of structures, including nanowires, fibers, nanospheres, and nanotoroids, the latter were previously observed only in considerably larger or co-assembly systems. Secondary structure analysis revealed that all assemblies possessed a β-sheet conformation. Additionally, in solvent combinations with high water ratios, z-FF formed rigid and self-healing hydrogels. X-ray crystallography revealed a "wishbone" structure, in which z-FF dimers are linked by hydrogen bonds mediated by methanol molecules, with a 2-fold screw symmetry along the c-axis. All-atom molecular dynamics (MD) simulations revealed conformations similar to the crystal structure. Coarse-grained MD simulated the assembly of the peptide into either fibers or spheres in different solvent systems, consistent with the experimental results. This work thus expands the building block library for the fabrication of nanostructures by peptide self-assembly.
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Affiliation(s)
- Noam Brown
- Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
- Department of Chemical Physics, School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Jiangtao Lei
- Department of Physics, State Key Laboratory of Surface Physics, Key Laboratory for Computational Physical Sciences (MOE), and Collaborative Innovation Center of Advanced Microstructures (Nanjing), Fudan University, Shanghai 200433, People’s Republic of China
| | - Chendi Zhan
- Department of Physics, State Key Laboratory of Surface Physics, Key Laboratory for Computational Physical Sciences (MOE), and Collaborative Innovation Center of Advanced Microstructures (Nanjing), Fudan University, Shanghai 200433, People’s Republic of China
| | - Linda J. W. Shimon
- Department of Chemical Research Support, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Lihi Adler-Abramovich
- Department of Oral Biology, the Goldschleger School of Dental Medicine, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Guanghong Wei
- Department of Physics, State Key Laboratory of Surface Physics, Key Laboratory for Computational Physical Sciences (MOE), and Collaborative Innovation Center of Advanced Microstructures (Nanjing), Fudan University, Shanghai 200433, People’s Republic of China
- Corresponding Authors: .
| | - Ehud Gazit
- Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
- Corresponding Authors: .
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19
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Mukherjee K, Ruan Q, Nutt S, Tao J, De Yoreo JJ, Moradian-Oldak J. Peptide-Based Bioinspired Approach to Regrowing Multilayered Aprismatic Enamel. ACS OMEGA 2018; 3:2546-2557. [PMID: 29623301 PMCID: PMC5879487 DOI: 10.1021/acsomega.7b02004] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2017] [Accepted: 02/22/2018] [Indexed: 05/28/2023]
Abstract
The gradual discovery of functional domains in native enamel matrix proteins has enabled the design of smart bioinspired peptides for tooth enamel mimetics and repair. In this study, we expanded upon the concept of biomineralization to design smaller amelogenin-inspired peptides with conserved functional domains for clinical translation. The synthetic peptides displayed a characteristic nanostructured scaffold reminiscent of 'nanospheres' seen in the enamel matrix and effectively controlled apatite nucleation in vitro resulting in the formation of smaller crystallites. Following application of the peptides to sectioned human molar teeth, a robust, oriented, synthetic aprismatic enamel was observed after 7 days of incubation in situ. There was a two-fold increase in the hardness and modulus of the regrown enamel-like apatite layers and an increase in the attachment of the tooth-regrown layer interface compared to control samples. Repeated peptide applications generated multiple enamel-like hydroxyapatite (HAP) layers of limited thickness produced by epitaxial growth in which c-axis oriented nanorods evolved on the surface of native enamel. We conclude that peptide analogues with active domains can effectively regulate the orientation of regenerated HAP layers to influence functional response. Moreover, this enamel biofabrication approach demonstrates the peptide-mediated growth of multiple microscale HAP arrays of organized microarchitecture with potential for enamel repair.
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Affiliation(s)
- Kaushik Mukherjee
- Center
for Craniofacial Molecular Biology, Division of Biomedical Sciences,
Herman Ostrow School of Dentistry, University
of Southern California, 2250 Alcazar Street, 90033 Los Angeles, United States
| | - Qichao Ruan
- Center
for Craniofacial Molecular Biology, Division of Biomedical Sciences,
Herman Ostrow School of Dentistry, University
of Southern California, 2250 Alcazar Street, 90033 Los Angeles, United States
| | - Steven Nutt
- Mork
Family Department of Chemical Engineering and Materials Science, University of Southern California, 3651 Watt Way, 90089 Los Angeles, United States
| | - Jinhui Tao
- Physical
Sciences Division, Pacific Northwest National
Laboratory, 902 Battelle
Blvd, 99352 Richland, United States
| | - James J. De Yoreo
- Physical
Sciences Division, Pacific Northwest National
Laboratory, 902 Battelle
Blvd, 99352 Richland, United States
| | - Janet Moradian-Oldak
- Center
for Craniofacial Molecular Biology, Division of Biomedical Sciences,
Herman Ostrow School of Dentistry, University
of Southern California, 2250 Alcazar Street, 90033 Los Angeles, United States
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20
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Le Norcy E, Lesieur J, Sadoine J, Rochefort GY, Chaussain C, Poliard A. Phosphorylated and Non-phosphorylated Leucine Rich Amelogenin Peptide Differentially Affect Ameloblast Mineralization. Front Physiol 2018; 9:55. [PMID: 29472869 PMCID: PMC5809816 DOI: 10.3389/fphys.2018.00055] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Accepted: 01/17/2018] [Indexed: 01/03/2023] Open
Abstract
The Leucine Rich Amelogenin Peptide (LRAP) is a product of alternative splicing of the amelogenin gene. As full length amelogenin, LRAP has been shown, in precipitation experiments, to regulate hydroxyapatite (HAP) crystal formation depending on its phosphorylation status. However, very few studies have questioned the impact of its phosphorylation status on enamel mineralization in biological models. Therefore, we have analyzed the effect of phosphorylated (+P) or non-phosphorylated (−P) LRAP on enamel formation in ameloblast-like cell lines and ex vivo cultures of murine postnatal day 1 molar germs. To this end, the mineral formed was analyzed by micro-computed tomography, Field Emission Scanning Electron Microscopy, Transmission Electron Microscopy, Selected Area Electon Diffraction imaging. Amelogenin gene transcription was evaluated by qPCR analysis. Our data show that, in both cells and germ cultures, LRAP is able to induce an up-regulation of amelogenin transcription independently of its phosphorylation status. Mineral formation is promoted by LRAP(+P) in all models, while LRAP(–P) essentially affects HAP crystal formation through an increase in crystal length and organization in ameloblast-like cells. Altogether, these data suggest a differential effect of LRAP depending on its phosphorylation status and on the ameloblast stage at the time of treatment. Therefore, LRAP isoforms can be envisioned as potential candidates for treatment of enamel lesions or defects and their action should be further evaluated in pathological models.
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Affiliation(s)
- Elvire Le Norcy
- EA2496 Faculté de Chirurgie Dentaire, Université Paris Descartes USPC, Paris, France.,APHP, Hôpital Bretonneau, Service d'Odontologie, Paris, France
| | - Julie Lesieur
- EA2496 Faculté de Chirurgie Dentaire, Université Paris Descartes USPC, Paris, France
| | - Jeremy Sadoine
- EA2496 Faculté de Chirurgie Dentaire, Université Paris Descartes USPC, Paris, France
| | - Gaël Y Rochefort
- EA2496 Faculté de Chirurgie Dentaire, Université Paris Descartes USPC, Paris, France
| | - Catherine Chaussain
- EA2496 Faculté de Chirurgie Dentaire, Université Paris Descartes USPC, Paris, France.,APHP, Hôpital Bretonneau, Service d'Odontologie, Paris, France
| | - Anne Poliard
- EA2496 Faculté de Chirurgie Dentaire, Université Paris Descartes USPC, Paris, France
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21
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Lacruz RS, Habelitz S, Wright JT, Paine ML. DENTAL ENAMEL FORMATION AND IMPLICATIONS FOR ORAL HEALTH AND DISEASE. Physiol Rev 2017; 97:939-993. [PMID: 28468833 DOI: 10.1152/physrev.00030.2016] [Citation(s) in RCA: 223] [Impact Index Per Article: 31.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 01/10/2017] [Accepted: 01/10/2017] [Indexed: 12/16/2022] Open
Abstract
Dental enamel is the hardest and most mineralized tissue in extinct and extant vertebrate species and provides maximum durability that allows teeth to function as weapons and/or tools as well as for food processing. Enamel development and mineralization is an intricate process tightly regulated by cells of the enamel organ called ameloblasts. These heavily polarized cells form a monolayer around the developing enamel tissue and move as a single forming front in specified directions as they lay down a proteinaceous matrix that serves as a template for crystal growth. Ameloblasts maintain intercellular connections creating a semi-permeable barrier that at one end (basal/proximal) receives nutrients and ions from blood vessels, and at the opposite end (secretory/apical/distal) forms extracellular crystals within specified pH conditions. In this unique environment, ameloblasts orchestrate crystal growth via multiple cellular activities including modulating the transport of minerals and ions, pH regulation, proteolysis, and endocytosis. In many vertebrates, the bulk of the enamel tissue volume is first formed and subsequently mineralized by these same cells as they retransform their morphology and function. Cell death by apoptosis and regression are the fates of many ameloblasts following enamel maturation, and what cells remain of the enamel organ are shed during tooth eruption, or are incorporated into the tooth's epithelial attachment to the oral gingiva. In this review, we examine key aspects of dental enamel formation, from its developmental genesis to the ever-increasing wealth of data on the mechanisms mediating ionic transport, as well as the clinical outcomes resulting from abnormal ameloblast function.
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Affiliation(s)
- Rodrigo S Lacruz
- Department of Basic Science and Craniofacial Biology, College of Dentistry, New York University, New York, New York; Department of Preventive and Restorative Dental Sciences, University of California, San Francisco, San Francisco, California; Department of Pediatric Dentistry, School of Dentistry, University of North Carolina, Chapel Hill, North Carolina; Herman Ostrow School of Dentistry, Center for Craniofacial Molecular Biology, University of Southern California, Los Angeles, California
| | - Stefan Habelitz
- Department of Basic Science and Craniofacial Biology, College of Dentistry, New York University, New York, New York; Department of Preventive and Restorative Dental Sciences, University of California, San Francisco, San Francisco, California; Department of Pediatric Dentistry, School of Dentistry, University of North Carolina, Chapel Hill, North Carolina; Herman Ostrow School of Dentistry, Center for Craniofacial Molecular Biology, University of Southern California, Los Angeles, California
| | - J Timothy Wright
- Department of Basic Science and Craniofacial Biology, College of Dentistry, New York University, New York, New York; Department of Preventive and Restorative Dental Sciences, University of California, San Francisco, San Francisco, California; Department of Pediatric Dentistry, School of Dentistry, University of North Carolina, Chapel Hill, North Carolina; Herman Ostrow School of Dentistry, Center for Craniofacial Molecular Biology, University of Southern California, Los Angeles, California
| | - Michael L Paine
- Department of Basic Science and Craniofacial Biology, College of Dentistry, New York University, New York, New York; Department of Preventive and Restorative Dental Sciences, University of California, San Francisco, San Francisco, California; Department of Pediatric Dentistry, School of Dentistry, University of North Carolina, Chapel Hill, North Carolina; Herman Ostrow School of Dentistry, Center for Craniofacial Molecular Biology, University of Southern California, Los Angeles, California
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22
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Stakkestad Ø, Lyngstadaas SP, Thiede B, Vondrasek J, Skålhegg BS, Reseland JE. Phosphorylation Modulates Ameloblastin Self-assembly and Ca 2+ Binding. Front Physiol 2017; 8:531. [PMID: 28798693 PMCID: PMC5529409 DOI: 10.3389/fphys.2017.00531] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Accepted: 07/10/2017] [Indexed: 01/10/2023] Open
Abstract
Ameloblastin (AMBN), an important component of the self-assembled enamel extra cellular matrix, contains several in silico predicted phosphorylation sites. However, to what extent these sites actually are phosphorylated and the possible effects of such post-translational modifications are still largely unknown. Here we report on in vitro experiments aimed at investigating what sites in AMBN are phosphorylated by casein kinase 2 (CK2) and protein kinase A (PKA) and the impact such phosphorylation has on self-assembly and calcium binding. All predicted sites in AMBN can be phosphorylated by CK2 and/or PKA. The experiments show that phosphorylation, especially in the exon 5 derived part of the molecule, is inversely correlated with AMBN self-assembly. These results support earlier findings suggesting that AMBN self-assembly is mostly dependent on the exon 5 encoded region of the AMBN gene. Phosphorylation was significantly more efficient when the AMBN molecules were in solution and not present as supramolecular assemblies, suggesting that post-translational modification of AMBN must take place before the enamel matrix molecules self-assemble inside the ameloblast cell. Moreover, phosphorylation of exon 5, and the consequent reduction in self-assembly, seem to reduce the calcium binding capacity of AMBN suggesting that post-translational modification of AMBN also can be involved in control of free Ca2+ during enamel extra cellular matrix biomineralization. Finally, it is speculated that phosphorylation can provide a functional crossroad for AMBN either to be phosphorylated and act as monomeric signal molecule during early odontogenesis and bone formation, or escape phosphorylation to be subsequently secreted as supramolecular assemblies that partake in enamel matrix structure and mineralization.
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Affiliation(s)
- Øystein Stakkestad
- Department of Biomaterials, Institute of Clinical Dentistry, University of OsloOslo, Norway
| | - Ståle P Lyngstadaas
- Department of Biomaterials, Institute of Clinical Dentistry, University of OsloOslo, Norway
| | - Bernd Thiede
- Section for Biochemistry and Molecular Biology, Department of Biosciences, University of OsloOslo, Norway
| | - Jiri Vondrasek
- Department of Bioinformatics, Institute of Organic Chemistry and Biochemistry, Czech Academy of SciencesPrague, Czechia
| | - Bjørn S Skålhegg
- Division of Molecular Nutrition, Department of Nutrition, University of OsloOslo, Norway
| | - Janne E Reseland
- Department of Biomaterials, Institute of Clinical Dentistry, University of OsloOslo, Norway
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23
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Gabe CM, Brookes SJ, Kirkham J. Preparative SDS PAGE as an Alternative to His-Tag Purification of Recombinant Amelogenin. Front Physiol 2017; 8:424. [PMID: 28670287 PMCID: PMC5472695 DOI: 10.3389/fphys.2017.00424] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Accepted: 06/01/2017] [Indexed: 11/21/2022] Open
Abstract
Recombinant protein technology provides an invaluable source of proteins for use in structure-function studies, as immunogens, and in the development of therapeutics. Recombinant proteins are typically engineered with "tags" that allow the protein to be purified from crude host cell extracts using affinity based chromatography techniques. Amelogenin is the principal component of the developing enamel matrix and a frequent focus for biomineralization researchers. Several groups have reported the successful production of recombinant amelogenins but the production of recombinant amelogenin free of any tags, and at single band purity on silver stained SDS PAGE is technically challenging. This is important, as rigorous structure-function research frequently demands a high degree of protein purity and fidelity of protein sequence. Our aim was to generate His-tagged recombinant amelogenin at single band purity on silver stained SDS PAGE for use in functionality studies after His-tag cleavage. An acetic acid extraction technique (previously reported to produce recombinant amelogenin at 95% purity directly from E. coli) followed by repeated rounds of nickel column affinity chromatography, failed to generate recombinant amelogenin at single band purity. This was because following an initial round of nickel column affinity chromatography, subsequent cleavage of the His-tag was not 100% efficient. A second round of nickel column affinity chromatography, used in attempts to separate the cleaved His-tag free recombinant from uncleaved His-tagged contaminants, was still unsatisfactory as cleaved recombinant amelogenin exhibited significant affinity for the nickel column. To solve this problem, we used preparative SDS PAGE to successfully purify cleaved recombinant amelogenins to single band purity on silver stained SDS PAGE. The resolving power of preparative SDS PAGE was such that His-tag based purification of recombinant amelogenin becomes redundant. We suggest that acetic acid extraction of recombinant amelogenin and subsequent purification using preparative SDS PAGE provides a simple route to highly purified His-tag free amelogenin for use in structure-function experiments and beyond.
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Affiliation(s)
| | - Steven J. Brookes
- Division of Oral Biology, School of Dentistry, University of LeedsLeeds, United Kingdom
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24
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Krishnaraju RK, Hart TC, Schleyer TK. Comparative Genomics and Structure Prediction of Dental Matrix Proteins. Adv Dent Res 2016; 17:100-3. [PMID: 15126218 DOI: 10.1177/154407370301700123] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Non-collagenous matrix proteins secreted by the ameloblasts (amelogenin) and odontoblasts (osteocalcin) play important roles in the mineralization of enamel and dentin. In this study, comparative genomics approaches were used to identify the functional domains and model the three-dimensional structure of amelogenin and osteocalcin, respectively. Multiple sequence analysis of amelogenin in different species showed a high degree of sequence conservation at the nucleotide and protein levels. At the protein level, motifs (a sequence pattern that occurs repeatedly in a group of related proteins or genes), conserved domains, secondary structural characteristics, and functional sites of amelogenin from lower phyla were similar to those of the higher-level mammals, reflecting the high degree of sequence conservation during vertebrate evolution. Osteocalcin, produced by both odontoblasts and osetoblasts, also showed sequence similarity between species. Three-dimensional structure predictions developed by modeling of conserved domains of osteocalcin supported a role for glutamic acid residues in the calcium mineralization process.
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Affiliation(s)
- R K Krishnaraju
- Center for Biomedical Informatics, University of Pittsburgh, PA 15261, USA.
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Margolis HC, Beniash E, Fowler CE. Role of Macromolecular Assembly of Enamel Matrix Proteins in Enamel Formation. J Dent Res 2016; 85:775-93. [PMID: 16931858 DOI: 10.1177/154405910608500902] [Citation(s) in RCA: 205] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Unlike other mineralized tissues, mature dental enamel is primarily (> 95% by weight) composed of apatitic crystals and has a unique hierarchical structure. Due to its high mineral content and organized structure, enamel has exceptional functional properties and is the hardest substance in the human body. Enamel formation (amelogenesis) is the result of highly orchestrated extracellular processes that regulate the nucleation, growth, and organization of forming mineral crystals. However, major aspects of the mechanism of enamel formation are not well-understood, although substantial evidence suggests that protein-protein and protein-mineral interactions play crucial roles in this process. The purpose of this review is a critical evaluation of the present state of knowledge regarding the potential role of the assembly of enamel matrix proteins in the regulation of crystal growth and the structural organization of the resulting enamel tissue. This review primarily focuses on the structure and function of amelogenin, the predominant enamel matrix protein. This review also provides a brief description of novel in vitro approaches that have used synthetic macromolecules ( i.e., surfactants and polymers) to regulate the formation of hierarchical inorganic (composite) structures in a fashion analogous to that believed to take place in biological systems, such as enamel. Accordingly, this review illustrates the potential for developing bio-inspired approaches to mineralized tissue repair and regeneration. In conclusion, the authors present a hypothesis, based on the evidence presented, that the full-length amelogenin uniquely regulates proper enamel formation through a process of cooperative mineralization, and not as a pre-formed matrix.
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Affiliation(s)
- H C Margolis
- Department of Biomineralization, The Forsyth Institute, 140 The Fenway, Boston, MA 02115, USA.
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Apicella A, Marascio M, Colangelo V, Soncini M, Gautieri A, Plummer CJG. Molecular dynamics simulations of the intrinsically disordered protein amelogenin. J Biomol Struct Dyn 2016; 35:1813-1823. [PMID: 27366858 DOI: 10.1080/07391102.2016.1196151] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Amelogenin refers to a class of intrinsically disordered proteins that are the major constituents of enamel matrix derivative (EMD), an extract of porcine fetal teeth used in regenerative periodontal therapy. Modifications in molecular conformation induced by external stresses, such as changes in temperature or pH, are known to reduce the effectiveness of EMD. However, detailed descriptions of the conformational behavior of native amelogenin are lacking in the open literature. In the present work, a molecular model for the secondary and tertiary structure of the full-length major porcine amelogenin P173 was constructed from its primary sequence by replica exchange molecular dynamics (REMD) simulations. The REMD results for isolated amelogenin molecules at different temperatures were shown to be consistent with the available spectroscopic data. They therefore represent an important first step toward the simulation of the intra- and intermolecular interactions that mediate self-organization in amelogenin and its behavior in the presence of other EMD components under conditions representative of its therapeutic application.
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Affiliation(s)
- Alessandra Apicella
- a Laboratoire de Technologie des Composites et Polymères (LTC) , Ecole Polytechnique Fédérale de Lausanne (EPFL) , Station 12, CH-1015 Lausanne , Switzerland
| | - Matteo Marascio
- a Laboratoire de Technologie des Composites et Polymères (LTC) , Ecole Polytechnique Fédérale de Lausanne (EPFL) , Station 12, CH-1015 Lausanne , Switzerland.,b Dipartimento di Elettronica, Informazione e Bioingegneria , Politecnico di Milano , Piazza Leonardo da Vinci 32, 20133 Milan , Italy
| | - Vincenzo Colangelo
- b Dipartimento di Elettronica, Informazione e Bioingegneria , Politecnico di Milano , Piazza Leonardo da Vinci 32, 20133 Milan , Italy
| | - Monica Soncini
- b Dipartimento di Elettronica, Informazione e Bioingegneria , Politecnico di Milano , Piazza Leonardo da Vinci 32, 20133 Milan , Italy
| | - Alfonso Gautieri
- b Dipartimento di Elettronica, Informazione e Bioingegneria , Politecnico di Milano , Piazza Leonardo da Vinci 32, 20133 Milan , Italy
| | - Christopher J G Plummer
- a Laboratoire de Technologie des Composites et Polymères (LTC) , Ecole Polytechnique Fédérale de Lausanne (EPFL) , Station 12, CH-1015 Lausanne , Switzerland
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Lokappa SB, Chandrababu KB, Moradian-Oldak J. Tooth enamel protein amelogenin binds to ameloblast cell membrane-mimicking vesicles via its N-terminus. Biochem Biophys Res Commun 2015; 464:956-61. [PMID: 26188506 PMCID: PMC4532586 DOI: 10.1016/j.bbrc.2015.07.082] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 07/16/2015] [Indexed: 11/18/2022]
Abstract
We have recently reported that the extracellular enamel protein amelogenin has affinity to interact with phospholipids and proposed that such interactions may play key roles in enamel biomineralization as well as reported amelogenin signaling activities. Here, in order to identify the liposome-interacting domains of amelogenin we designed four different amelogenin mutants containing only a single tryptophan at positions 25, 45, 112 and 161. Circular dichroism studies of the mutants confirmed that they are structurally similar to the wild-type amelogenin. Utilizing the intrinsic fluorescence of single tryptophan residue and fluorescence resonance energy transfer [FRET], we analyzed the accessibility and strength of their binding with an ameloblast cell membrane-mimicking model membrane (ACML) and a negatively charged liposome used as a membrane model. We found that amelogenin has membrane-binding ability mainly via its N-terminal, close to residues W25 and W45. Significant blue shift was also observed in the fluorescence of a N-terminal peptide following addition of liposomes. We suggest that, among other mechanisms, enamel malformation in cases of Amelogenesis Imperfecta (AI) with mutations at the N-terminal may be the result of defective amelogenin-cell interactions.
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Affiliation(s)
- Sowmya Bekshe Lokappa
- Center for Craniofacial Molecular Biology, Division of Biomedical Sciences, Herman Ostrow School of Dentistry, University of Southern California, 2250 Alcazar Street, Los Angeles, CA 90033, USA
| | - Karthik Balakrishna Chandrababu
- Center for Craniofacial Molecular Biology, Division of Biomedical Sciences, Herman Ostrow School of Dentistry, University of Southern California, 2250 Alcazar Street, Los Angeles, CA 90033, USA
| | - Janet Moradian-Oldak
- Center for Craniofacial Molecular Biology, Division of Biomedical Sciences, Herman Ostrow School of Dentistry, University of Southern California, 2250 Alcazar Street, Los Angeles, CA 90033, USA.
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Abstract
Mature tooth enamel is acellular and does not regenerate itself. Developing technologies that rebuild tooth enamel and preserve tooth structure is therefore of great interest. Considering the importance of amelogenin protein in dental enamel formation, its ability to control apatite mineralization in vitro, and its potential to be applied in fabrication of future bio-inspired dental material this review focuses on two major subjects: amelogenin and enamel biomimetics. We review the most recent findings on amelogenin secondary and tertiary structural properties with a focus on its interactions with different targets including other enamel proteins, apatite mineral, and phospholipids. Following a brief overview of enamel hierarchical structure and its mechanical properties we will present the state-of-the-art strategies in the biomimetic reconstruction of human enamel.
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Affiliation(s)
- Qichao Ruan
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, CA 90033, USA
| | - Janet Moradian-Oldak
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, CA 90033, USA
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Geng S, White SN, Paine ML, Snead ML. Protein Interaction between Ameloblastin and Proteasome Subunit α Type 3 Can Facilitate Redistribution of Ameloblastin Domains within Forming Enamel. J Biol Chem 2015; 290:20661-20673. [PMID: 26070558 DOI: 10.1074/jbc.m115.640185] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Indexed: 11/06/2022] Open
Abstract
Enamel is a bioceramic tissue composed of thousands of hydroxyapatite crystallites aligned in parallel within boundaries fabricated by a single ameloblast cell. Enamel is the hardest tissue in the vertebrate body; however, it starts development as a self-organizing assembly of matrix proteins that control crystallite habit. Here, we examine ameloblastin, a protein that is initially distributed uniformly across the cell boundary but redistributes to the lateral margins of the extracellular matrix following secretion thus producing cell-defined boundaries within the matrix and the mineral phase. The yeast two-hybrid assay identified that proteasome subunit α type 3 (Psma3) interacts with ameloblastin. Confocal microscopy confirmed Psma3 co-distribution with ameloblastin at the ameloblast secretory end piece. Co-immunoprecipitation assay of mouse ameloblast cell lysates with either ameloblastin or Psma3 antibody identified each reciprocal protein partner. Protein engineering demonstrated that only the ameloblastin C terminus interacts with Psma3. We show that 20S proteasome digestion of ameloblastin in vitro generates an N-terminal cleavage fragment consistent with the in vivo pattern of ameloblastin distribution. These findings suggest a novel pathway participating in control of protein distribution within the extracellular space that serves to regulate the protein-mineral interactions essential to biomineralization.
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Affiliation(s)
- Shuhui Geng
- Center for Craniofacial Molecular Biology, University of Southern California, Los Angeles, California 90033
| | - Shane N White
- School of Dentistry, UCLA, Los Angeles, California 90095
| | - Michael L Paine
- Center for Craniofacial Molecular Biology, University of Southern California, Los Angeles, California 90033
| | - Malcolm L Snead
- Center for Craniofacial Molecular Biology, University of Southern California, Los Angeles, California 90033.
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Lignon G, de la Dure-Molla M, Dessombz A, Berdal A, Babajko S. [Enamel: a unique self-assembling in mineral world]. Med Sci (Paris) 2015; 31:515-21. [PMID: 26059302 DOI: 10.1051/medsci/20153105013] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Enamel is a unique tissue in vertebrates, acellular, formed on a labile scaffolding matrix and hypermineralized. The ameloblasts are epithelial cells in charge of amelogenesis. They secrete a number of matrix proteins degraded by enzymes during enamel mineralization. This ordered cellular and extracellular events imply that any genetic or environmental perturbation will produce indelible and recognizable defects. The specificity of defects will indicate the affected cellular process. Thus, depending on the specificity of alterations, the teratogenic event can be retrospectively established. Advances in the field allow to use enamel defects as diagnostic tools for molecular disorders. The multifunctionality of enamel peptides is presently identified from their chemical roles in mineralization to cell signaling, constituting a source of concrete innovations in regenerative medicine.
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Affiliation(s)
- Guilhem Lignon
- Laboratoire de physiopathologie orale moléculaire, Inserm UMRS 1138, centre de recherche des Cordeliers, université Paris Diderot-Paris 7, université Pierre et Marie Curie-Paris 6, université Paris Descartes-Paris 5, 15-21, rue de l'École de Médecine, 75270 Paris cedex 06, France
| | - Muriel de la Dure-Molla
- Laboratoire de physiopathologie orale moléculaire, Inserm UMRS 1138, centre de recherche des Cordeliers, université Paris Diderot-Paris 7, université Pierre et Marie Curie-Paris 6, université Paris Descartes-Paris 5, 15-21, rue de l'École de Médecine, 75270 Paris cedex 06, France - Centre de référence des malformations rares de la face et de la cavité buccale, CRMR-MAFACE, hôpital Rothschild, APHP, Paris, France
| | - Arnaud Dessombz
- Laboratoire de physiopathologie orale moléculaire, Inserm UMRS 1138, centre de recherche des Cordeliers, université Paris Diderot-Paris 7, université Pierre et Marie Curie-Paris 6, université Paris Descartes-Paris 5, 15-21, rue de l'École de Médecine, 75270 Paris cedex 06, France
| | - Ariane Berdal
- Laboratoire de physiopathologie orale moléculaire, Inserm UMRS 1138, centre de recherche des Cordeliers, université Paris Diderot-Paris 7, université Pierre et Marie Curie-Paris 6, université Paris Descartes-Paris 5, 15-21, rue de l'École de Médecine, 75270 Paris cedex 06, France - Centre de référence des malformations rares de la face et de la cavité buccale, CRMR-MAFACE, hôpital Rothschild, APHP, Paris, France
| | - Sylvie Babajko
- Laboratoire de physiopathologie orale moléculaire, Inserm UMRS 1138, centre de recherche des Cordeliers, université Paris Diderot-Paris 7, université Pierre et Marie Curie-Paris 6, université Paris Descartes-Paris 5, 15-21, rue de l'École de Médecine, 75270 Paris cedex 06, France
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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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Snead ML. Biomineralization of a self-assembled-, soft-matrix precursor: Enamel. JOM (WARRENDALE, PA. : 1989) 2015; 67:788-795. [PMID: 26052186 PMCID: PMC4454482 DOI: 10.1007/s11837-015-1305-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Enamel is the bioceramic covering of teeth, a composite tissue composed of hierarchical organized hydroxyapatite crystallites fabricated by cells under physiologic pH and temperature. Enamel material properties resist wear and fracture to serve a lifetime of chewing. Understanding the cellular and molecular mechanisms for enamel formation may allow a biology-inspired approach to material fabrication based on self-assembling proteins that control form and function. Genetic understanding of human diseases expose insight from Nature's errors by exposing critical fabrication events that can be validated experimentally and duplicated in mice using genetic engineering to phenocopy the human disease so that it can be explored in detail. This approach led to assessment of amelogenin protein self-assembly which, when altered, disrupts fabrication of the soft enamel protein matrix. A misassembled protein matrix precursor results in loss of cell to matrix contacts essential to fabrication and mineralization.
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Affiliation(s)
- Malcolm L Snead
- Center for Craniofacial Molecular Biology Hermann Ostrow School of Dentistry of USC The University of Southern California 2250 Alcazar St., CSA Room 142, HSC Los Angeles, CA 90032
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Bonde J, Bülow L. Random mutagenesis of amelogenin for engineering protein nanoparticles. Biotechnol Bioeng 2015; 112:1319-26. [DOI: 10.1002/bit.25556] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Accepted: 01/27/2015] [Indexed: 01/11/2023]
Affiliation(s)
- Johan Bonde
- Division of Pure and Applied Biochemistry; Center for Applied Life Sciences; Lund University; 221 00 Lund Sweden
| | - Leif Bülow
- Division of Pure and Applied Biochemistry; Center for Applied Life Sciences; Lund University; 221 00 Lund Sweden
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Moeinzadeh S, Jabbari E. Morphogenic Peptides in Regeneration of Load Bearing Tissues. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 881:95-110. [PMID: 26545746 DOI: 10.1007/978-3-319-22345-2_6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Morphogenic proteins due to their short half-life require high doses of growth factors in regeneration of load bearing tissues which leads to undesirable side effects. These side effects include bone overgrowth, tumor formation and immune reaction. An alternative approach to reduce undesirable side effects of proteins in regenerative medicine is to use morphogenic peptides derived from the active domains of morphogenic proteins or soluble and insoluble components of the extracellular matrix of mineralized load bearing tissues to induce differentiation of progenitor cells, mineralization, maturation and bone formation. In that regard, many peptides with osteogenic activity have been discovered. These include peptides derived from bone morphogenic proteins (BMPs), those based on interaction with integrin and heparin-binding receptors, collagen derived peptides, peptides derived from other soluble ECM proteins such as bone sialoprotein and enamel matrix proteins, and those peptides derived from vasculoinductive and neuro-inductive proteins. Although these peptides show significant osteogenic activity in vitro and increase mineralization and bone formation in animal models, they are not widely used in clinical orthopedic applications as an alternative to morphogenic proteins. This is partly due to the limited availability of data on structure and function of morphogenic peptides in physiological medium, particularly in tissue engineered scaffolds. Due to their amphiphilic nature, peptides spontaneously self-assemble and aggregate into micellar structures in physiological medium. Aggregation alters the sequence of amino acids in morphogenic peptides that interact with cell surface receptors thus affecting osteogenic activity of the peptide. Aggregation and micelle formation can dramatically reduce the active concentration of morphogenic peptides with many-fold increase in peptide concentration in physiological medium. Other factors that affect bioactivity are the non-specific interaction of morphogenic peptides with lipid bilayer of the cell membrane, interaction of the peptide with cell surface receptors that do not specifically induce osteogenesis leading to less-than-optimal osteogenic activity of the peptide, and less-than-optimal interaction of the peptide with osteogenic receptors on the cell surface. Covalent attachment or physical interaction with the tissue engineered matrix can also alter the bioactivity of morphogenic peptides and lead to a lower extent of osteogenesis and bone formation. This chapter reviews advances in discovery of morphogenic peptide, their structural characterization, and challenges in using morphogenic peptides in clinical applications as growth factors in tissue engineered devices for regeneration of load bearing tissues.
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Affiliation(s)
- Seyedsina Moeinzadeh
- Biomimetic Materials and Tissue Engineering Laboratories, Department of Chemical Engineering, Swearingen Engineering Center, Rm 2C11, University of South Carolina, Columbia, SC, 29208, USA
| | - Esmaiel Jabbari
- Biomimetic Materials and Tissue Engineering Laboratories, Department of Chemical Engineering, Swearingen Engineering Center, Rm 2C11, University of South Carolina, Columbia, SC, 29208, USA.
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Ruan Q, Moradian-Oldak J. Amelogenin and enamel biomimetics. J Mater Chem B 2015. [DOI: 10.1039/c5tb00163c and 21=21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Mature tooth enamel is acellular and does not regenerate itself.
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Affiliation(s)
- Qichao Ruan
- Center for Craniofacial Molecular Biology
- Herman Ostrow School of Dentistry
- University of Southern California
- Los Angeles
- USA
| | - Janet Moradian-Oldak
- Center for Craniofacial Molecular Biology
- Herman Ostrow School of Dentistry
- University of Southern California
- Los Angeles
- USA
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Buchko GW, Shaw WJ. Improved protocol to purify untagged amelogenin - Application to murine amelogenin containing the equivalent P70→T point mutation observed in human amelogenesis imperfecta. Protein Expr Purif 2014; 105:14-22. [PMID: 25306873 DOI: 10.1016/j.pep.2014.09.020] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Accepted: 09/17/2014] [Indexed: 11/16/2022]
Abstract
Amelogenin is the predominant extracellular protein responsible for converting carbonated hydroxyapatite into dental enamel, the hardest and most heavily mineralized tissue in vertebrates. Despite much effort, the precise mechanism by which amelogenin regulates enamel formation is not fully understood. To assist efforts aimed at understanding the biochemical mechanism of enamel formation, more facile protocols to purify recombinantly expressed amelogenin, ideally without any tag to assist affinity purification, are advantageous. Here we describe an improved method to purify milligram quantities of amelogenin that exploits its high solubility in 2% glacial acetic acid under conditions of low ionic strength. The method involves heating the frozen cell pellet for two 15min periods at ∼70°C with 2min of sonication in between, dialysis twice in 2% acetic acid (1:250 v/v), and reverse phase chromatography. A further improvement in yield is obtained by resuspending the frozen cell pellet in 6M guanidine hydrochloride in the first step. The acetic acid heating method is illustrated with a murine amelogenin containing the corresponding P70→T point mutation observed in an human amelogenin associated with amelogenesis imperfecta (P71T), while the guanidine hydrochloride heating method is illustrated with wild type murine amelogenin (M180). The self-assembly properties of P71T were probed by NMR chemical shift perturbation studies as a function of protein (0.1-1.8mM) and NaCl (0-367mM) concentration. Relative to similar studies with wild type murine amelogenin, P71T self-associates at lower protein or salt concentrations with the interactions initiated near the N-terminus.
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Affiliation(s)
- Garry W Buchko
- Fundamental and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA 99352, USA.
| | - Wendy J Shaw
- Fundamental and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA 99352, USA
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de Moraes Ramos-Perez FM, do Espírito Santo AR, da Cruz Perez DE, Novaes PD, Bóscolo FN, Line SRP, de Almeida SM. Ionizing radiation effects on the secretory-stage ameloblasts and enamel organic extracellular matrix. RADIATION AND ENVIRONMENTAL BIOPHYSICS 2014; 53:589-598. [PMID: 24699801 DOI: 10.1007/s00411-014-0539-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Accepted: 03/23/2014] [Indexed: 06/03/2023]
Abstract
This study assessed the effects of high doses of ionizing radiation on eruption rate, odontogenic region morphology, secretory-stage ameloblasts, and enamel organic extracellular matrix (EOECM) of rat maxillary incisors. For the study, 30 male rats were divided into three experimental groups: control (non-irradiated), irradiated by 15 Gy, and irradiated by 25 Gy. Irradiated groups received a single dose of 15 or 25 Gy of X-rays in the head and neck region. The maxillary incisor eruption rate was measured. Sections of 5-µm thickness of the maxillary incisor odontogenic regions were evaluated using bright field light microscopy. Ultrathin sections of secretory ameloblasts and their EOECM were analyzed by transmission electron microscopy (TEM). Irradiated groups showed significantly diminished eruption rate values at the 4th and at the 6th day after irradiation. Reduced optical retardation values were observed in the irradiated groups. The odontogenic region of maxillary incisors from irradiated rats exhibited altered and poorly organized preameloblasts. TEM showed degeneration areas in the secretory-stage EOECM and several autophagosomes in the secretory ameloblasts from irradiated animals. In conclusion, high radiation doses delay eruption and induce disturbances in secretory ameloblasts and EOECM of rat maxillary incisors. These findings may be associated with structural defects of mature enamel.
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Affiliation(s)
- Flávia Maria de Moraes Ramos-Perez
- Área de Radiologia Odontológica, Departamento de Clinica e Odontologia Preventiva, Universidade Federal de Pernambuco, Avenida Prof. Moraes Rego, 1235, Cidade Universitária, CEP 50670-901, Recife, PE, Brazil,
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Buchko GW, Lin G, Tarasevich BJ, Shaw WJ. A solution NMR investigation into the impaired self-assembly properties of two murine amelogenins containing the point mutations T21→I or P41→T. Arch Biochem Biophys 2013; 537:217-24. [PMID: 23896516 PMCID: PMC3788651 DOI: 10.1016/j.abb.2013.07.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Revised: 07/10/2013] [Accepted: 07/12/2013] [Indexed: 10/26/2022]
Abstract
Amelogenesis imperfecta describes a group of inherited disorders that results in defective tooth enamel. Two disorders associated with human amelogenesis imperfecta are the point mutations T21→I or P40→T in amelogenin, the dominant protein present during the early stages of enamel biomineralization. The biophysical properties of wildtype murine amelogenin (M180) and two proteins containing the equivalent mutations in murine amelogenin, T21→I (M180-I) and P41→T (M180-T), were probed by NMR spectroscopy. At low protein concentration (0.1mM), M180, M180-I, and M180-T are predominately monomeric at pH 3.0 in 2% acetic acid and neither mutation produces a major structural change. Chemical shift perturbation studies as a function of protein (0.1-1.8mM) or NaCl (0-400mM) concentrations show that the mutations affect the self-association properties by causing self-assembly at lower protein or salt concentrations, relative to wildtype amelogenin, with the largest effect observed for M180-I. Under both conditions, the premature self-assembly is initiated near the N-terminus, providing further evidence for the importance of this region in the self-assembly process. The self-association of M180-I and M180-T at lower protein concentrations and lower ionic strengths than wildtype M180 may account for the clinical phenotypes of these mutations, defective enamel formation.
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Affiliation(s)
- Garry W. Buchko
- Fundamental Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA 99352, USA
| | - Genyao Lin
- Fundamental Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA 99352, USA
| | - Barbara J. Tarasevich
- Fundamental Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA 99352, USA
| | - Wendy J. Shaw
- Fundamental Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA 99352, USA
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CryoTEM study of effects of phosphorylation on the hierarchical assembly of porcine amelogenin and its regulation of mineralization in vitro. J Struct Biol 2013; 183:250-7. [PMID: 23707542 DOI: 10.1016/j.jsb.2013.05.011] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2013] [Revised: 04/22/2013] [Accepted: 05/15/2013] [Indexed: 11/21/2022]
Abstract
Amelogenin, the major extracellular enamel matrix protein, plays a critical role in regulating the growth and organization of enamel. Assembly and mineralization of full-length native (P173) and recombinant (rP172) porcine amelogenins were studied by cryogenic Transmission Electron Microscopy (cryoTEM). The cryoTEM revealed that both native and recombinant porcine amelogenins undergo step-wise self-assembly. Although the overall structural organization of P173 and rP172 oligomers was similar and resembled oligomers of murine recombinant amelogenin rM179, there were subtle differences suggesting that a single phosphorylated serine present in P173 might affect amelogenin self-assembly. Our mineralization studies demonstrated that both P173 and rP172 oligomers stabilize initial mineral clusters. Importantly, however, rP172 regulated the organization of initial mineral clusters into linear chains and guided the formation of parallel arrays of elongated mineral particles, which are the hallmark of enamel structural organization. These results are similar to those obtained previously using full-length recombinant murine amelogenin (Fang et al., 2011a). In contrast to that seen with rP172, phosphorylated P173 strongly inhibits mineralization for extended periods of time. We propose that these differences might be due to the differences in the structural organization and charge distribution between P173 and rP172. Overall our studies indicate that self-assembly of amelogenin and the mechanisms of its control over mineralization might be universal across different mammalian species. Our data also provide new insight into the effect of phosphorylation on amelogenin self-assembly and its regulation of mineralization.
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40
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Bromley KM, Lakshminarayanan R, Thompson M, Lokappa SB, Gallon VA, Cho KR, Qiu SR, Moradian-Oldak J. Amelogenin processing by MMP-20 prevents protein occlusion inside calcite crystals. CRYSTAL GROWTH & DESIGN 2012; 12:4897-4905. [PMID: 23226976 PMCID: PMC3513936 DOI: 10.1021/cg300754a] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Calcite crystals were grown in the presence of full-length amelogenin and during its proteolysis by recombinant human matrix metalloproteinase 20 (rhMMP-20). Recombinant porcine amelogenin (rP172) altered the shape of calcite crystals by inhibiting the growth of steps on the {104} faces and became occluded inside the crystals. Upon co-addition of rhMMP-20, the majority of the protein was digested resulting in a truncated amelogenin lacking the C-terminal segment. In rP172-rhMMP-20 samples, the occlusion of amelogenin into the calcite crystals was drastically decreased. Truncated amelogenin (rP147) and the 25-residue C-terminal domain produced crystals with regular shape and less occluded organic material. Removal of the C-terminal diminished the affinity of amelogenin to the crystals and therefore prevented occlusion. We hypothesize that HAP and calcite interact with amelogenin in a similar manner. In the case of each material, full-length amelogenin binds most strongly, truncated amelogenin binds weakly and the C-terminus alone has the weakest interaction. Regarding enamel crystal growth, the prevention of occlusion into maturing enamel crystals might be a major benefit resulting from the selective cleavage of amelogenin at the C-terminus by MMP-20. Our data have important implications for understanding the hypomineralized enamel phenotype in cases of amelogenesis imperfecta resulting from MMP-20 mutations and will contribute to the design of enamel inspired biomaterials.
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Affiliation(s)
- Keith M. Bromley
- Center for Craniofacial Molecular Biology, University of Southern California, 2250 Alcazar Street, Los Angeles, CA 90033, USA
| | - Rajamani Lakshminarayanan
- Centre for Translational Medicine, NUS, Yong Loo Lin School of Medicine, 14 Medical Drive, Singapore Eye Research Institute (SERI), Level 8-South Core, Singapore 117599
| | - Mitchell Thompson
- Center for Craniofacial Molecular Biology, University of Southern California, 2250 Alcazar Street, Los Angeles, CA 90033, USA
| | - Sowmya B. Lokappa
- Center for Craniofacial Molecular Biology, University of Southern California, 2250 Alcazar Street, Los Angeles, CA 90033, USA
| | - Victoria A. Gallon
- Center for Craniofacial Molecular Biology, University of Southern California, 2250 Alcazar Street, Los Angeles, CA 90033, USA
| | - Kang R. Cho
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, USA
- Lawrence Berkeley National Laboratory, One Cyclotron Rd., MS 67R1235A, Berkeley, CA 94720, USA
| | - S. Roger Qiu
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - Janet Moradian-Oldak
- Center for Craniofacial Molecular Biology, University of Southern California, 2250 Alcazar Street, Los Angeles, CA 90033, USA
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41
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Bazin D, Daudon M, Combes C, Rey C. Characterization and some physicochemical aspects of pathological microcalcifications. Chem Rev 2012; 112:5092-120. [PMID: 22809072 DOI: 10.1021/cr200068d] [Citation(s) in RCA: 145] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- D Bazin
- Laboratoire de Physique des Solides, CNRS, Université Paris-Sud, 91405 Orsay, France.
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42
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Holcroft J, Ganss B. Identification of amelotin- and ODAM-interacting enamel matrix proteins using the yeast two-hybrid system. Eur J Oral Sci 2012; 119 Suppl 1:301-6. [PMID: 22243260 DOI: 10.1111/j.1600-0722.2011.00870.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The formation of dental enamel is a prototype of functional tissue development through biomineralization. Amelotin (AMTN) is a recently discovered secreted enamel protein predominantly expressed during the maturation stage of enamel formation. It accumulates in a basal lamina-like structure at the interface between ameloblasts and enamel mineral and it co-localizes with another recently described enamel protein, odontogenic ameloblast-associated protein (ODAM). The purpose of this study was to determine whether AMTN and ODAM bind to each other and/or to other well-established enamel matrix proteins. The coding sequences of all enamel proteins were cloned into appropriate vectors of the GAL4-based Matchmaker Gold Yeast Two-Hybrid System. The growth of yeast cells on selective media and color induction were used as indicators for reporter gene expression through protein-protein interactions in combinations of prey and bait constructs. We found that AMTN interacts with itself and with ODAM, but not with amelogenin (AMEL), ameloblastin (AMBN), or enamelin (ENAM). Using ODAM as bait, the interaction with AMTN was confirmed. Furthermore, ODAM was found to bind to itself and to AMBN, as well as weakly to AMEL but not to ENAM. We propose a model where the distinct expression of AMTN and ODAM and their interaction are involved in defining the enamel microstructure at the enamel surface.
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Affiliation(s)
- James Holcroft
- Matrix Dynamics Group, University of Toronto, Faculty of Dentistry, Toronto, ON, Canada
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43
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Le Norcy E, Kwak SY, Allaire M, Fratzl P, Yamakoshi Y, Simmer JP, Margolis HC. Effect of phosphorylation on the interaction of calcium with leucine-rich amelogenin peptide. Eur J Oral Sci 2012; 119 Suppl 1:97-102. [PMID: 22243234 DOI: 10.1111/j.1600-0722.2011.00900.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Amelogenin undergoes self-assembly and plays an essential role in guiding enamel mineral formation. The leucine-rich amelogenin peptide (LRAP) is an alternative splice product of the amelogenin gene and is composed of the N terminus (containing the only phosphate group) and the C terminus of full-length amelogenin. This study was conducted to investigate further the role of phosphorylation in LRAP self-assembly in the presence and absence of calcium using small angle X-ray scattering (SAXS). Consistent with our previous dynamic light-scattering findings for phosphorylated (+P) and non-phosphorylated (-P) LRAP, SAXS analyses revealed radii of gyration (R(g)) for LRAP(-P) (46.3-48.0 Å) that were larger than those for LRAP(+P) (25.0-27.4 Å) at pH 7.4. However, added calcium (up to 2.5 mM) induced significant increases in the R(g) of LRAP(+P) (up to 46.4 Å), while it had relatively little effect on LRAP(-P) particle size. Furthermore, SAXS analyses suggested compact folded structures for LRAP(-P) in the presence and absence of calcium, whereas the conformation of LRAP(+P) changed from an unfolded structure to a more compact structure upon the addition of calcium. We conclude that the single phosphate group in LRAP(+P) induces functionally important conformational changes, suggesting that phosphorylation may also influence amelogenin conformation and protein-mineral interactions during the early stages of amelogenesis.
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Affiliation(s)
- Elvire Le Norcy
- Department of Biomineralization, The Forsyth Institute, Cambridge, MA 02142, USA
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44
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Calvaresi M, Höfinger S, Zerbetto F. Local Ice Melting by an Antifreeze Protein. Biomacromolecules 2012; 13:2046-52. [DOI: 10.1021/bm300366f] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Matteo Calvaresi
- Dipartimento di
Chimica “G. Ciamician”, Università di Bologna, Via F. Selmi 2, 40126 Bologna, Italy
| | - Siegfried Höfinger
- Dipartimento di
Chimica “G. Ciamician”, Università di Bologna, Via F. Selmi 2, 40126 Bologna, Italy
- Department of Physics, Michigan Technological University, 1400
Townsend Drive, 49931 Houghton, Michigan, United States
| | - Francesco Zerbetto
- Dipartimento di
Chimica “G. Ciamician”, Università di Bologna, Via F. Selmi 2, 40126 Bologna, Italy
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45
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Lacruz RS, Hacia JG, Bromage TG, Boyde A, Lei Y, Xu Y, Miller JD, Paine ML, Snead ML. The circadian clock modulates enamel development. J Biol Rhythms 2012; 27:237-45. [PMID: 22653892 PMCID: PMC3511783 DOI: 10.1177/0748730412442830] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Fully mature enamel is about 98% mineral by weight. While mineral crystals appear very early during its formative phase, the newly secreted enamel is a soft gel-like matrix containing several enamel matrix proteins of which the most abundant is amelogenin (Amelx). Histological analysis of mineralized dental enamel reveals markings called cross-striations associated with daily increments of enamel formation, as evidenced by injections of labeling dyes at known time intervals. The daily incremental growth of enamel has led to the hypothesis that the circadian clock might be involved in the regulation of enamel development. To identify daily rhythms of clock genes and Amelx, we subjected murine ameloblast cells to serum synchronization to analyze the expression of the circadian transcription factors Per2 and Bmal1 by real-time PCR. Results indicate that these key genetic regulators of the circadian clock are expressed in synchronized murine ameloblast cell cultures and that their expression profile follows a circadian pattern with acrophase and bathyphase for both gene transcripts in antiphase. Immunohistological analysis confirms the protein expression of Bmal and Cry in enamel cells. Amelx expression in 2-day postnatal mouse molars dissected every 4 hours for a duration of 48 hours oscillated with an approximately 24-hour period, with a significant approximately 2-fold decrease in expression during the dark period compared to the light period. The expression of genes involved in bicarbonate production (Car2) and transport (Slc4a4), as well as in enamel matrix endocytosis (Lamp1), was greater during the dark period, indicating that ameloblasts express these proteins when Amelx expression is at the nadir. The human and mouse Amelx genes each contain a single nonconserved E-box element within 10 kb upstream of their respective transcription start sites. We also found that within 2 kb of the transcription start site of the human NFYA gene, which encodes a positive regulator of amelogenin, there is an E-box element that is conserved in rodents and other mammals. Moreover, we found that Nfya expression in serum-synchronized murine ameloblasts oscillated with a strong 24-hour rhythm. Taken together, our data support the hypothesis that the circadian clock temporally regulates enamel development.
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Affiliation(s)
- Rodrigo S Lacruz
- Center for Craniofacial Molecular Biology, Ostrow School of Dentistry, University of Southern California, Los Angeles, CA 90033, USA.
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46
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Sa Y, Wang Z, Ma X, Lei C, Liang S, Sun L, Jiang T, Wang Y. Investigation of three home-applied bleaching agents on enamel structure and mechanical properties: an in situ study. JOURNAL OF BIOMEDICAL OPTICS 2012; 17:035002. [PMID: 22502559 DOI: 10.1117/1.jbo.17.3.035002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The safety of at-home tooth bleaching, based upon carbamide peroxide (CP) or hydrogen peroxide (HP) as the active agent, has been questioned. The aim of the present study was to investigate the effects of three differently concentrated home-applied bleaching agents on human enamel under in situ conditions. Sixty specimens were divided randomly into four groups and treated with 10% CP, 15% CP, 20% CP, and distilled water, respectively. Raman spectroscopy, attenuated total reflectance-infrared (ATR-IR) spectroscopy, atomic force microscopy (AFM), microhardness, and fracture toughness (FT) measurements were conducted to determine variations on enamel structure and mechanical properties before and after the bleaching process. Raman revealed little variation of Raman relative intensity after treatment with CP, which was consistent with the results of ATR-IR, AFM, and microhardness analyses. In addition, laser-induced fluorescence (LIF) intensity, and FT showed significant decreases on CP-treated specimens. These findings suggested there were minimal demineralization effects of the three at-home bleaching agents on enamel in situ. However, the decrease of LIF intensity and FT on enamel seemed to be inevitable.
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Affiliation(s)
- Yue Sa
- Wuhan University, The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan 430079, China
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47
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Cheng ZJ, Wang Q, Wang XM, Cui FZ, Ge J, Chen D, Tian LL. Enamel distribution, structure and mechanical alterations in col1-caPPR mice molar. Arch Oral Biol 2011; 56:1020-6. [DOI: 10.1016/j.archoralbio.2011.03.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2010] [Revised: 03/21/2011] [Accepted: 03/22/2011] [Indexed: 10/18/2022]
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48
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Bromley KM, Kiss AS, Lokappa SB, Lakshminarayanan R, Fan D, Ndao M, Evans JS, Moradian-Oldak J. Dissecting amelogenin protein nanospheres: characterization of metastable oligomers. J Biol Chem 2011; 286:34643-53. [PMID: 21840988 DOI: 10.1074/jbc.m111.250928] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Amelogenin self-assembles to form an extracellular protein matrix, which serves as a template for the continuously growing enamel apatite crystals. To gain further insight into the molecular mechanism of amelogenin nanosphere formation, we manipulated the interactions between amelogenin monomers by altering pH, temperature, and protein concentration to create isolated metastable amelogenin oligomers. Recombinant porcine amelogenins (rP172 and rP148) and three different mutants containing only a single tryptophan (Trp(161), Trp(45), and Trp(25)) were used. Dynamic light scattering and fluorescence studies demonstrated that oligomers were metastable and in constant equilibrium with monomers. Stable oligomers with an average hydrodynamic radius (R(H)) of 7.5 nm were observed at pH 5.5 between 4 and 10 mg · ml(-1). We did not find any evidence of a significant increase in folding upon self-association of the monomers into oligomers, indicating that they are disordered. Fluorescence experiments with single tryptophan amelogenins revealed that upon oligomerization the C terminus of amelogenin (around residue Trp(161)) is exposed at the surface of the oligomers, whereas the N-terminal region around Trp(25) and Trp(45) is involved in protein-protein interaction. The truncated rP148 formed similar but smaller oligomers, suggesting that the C terminus is not critical for amelogenin oligomerization. We propose a model for nanosphere formation via oligomers, and we predict that nanospheres will break up to form oligomers in mildly acidic environments via histidine protonation. We further suggest that oligomeric structures might be functional components during maturation of enamel apatite.
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Affiliation(s)
- Keith M Bromley
- Center for Craniofacial Molecular Biology, Ostrow School of Dentistry, University of Southern California, Los Angeles, California 90033, USA
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49
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Altered self-assembly and apatite binding of amelogenin induced by N-terminal proline mutation. Arch Oral Biol 2011; 56:331-6. [PMID: 21081224 DOI: 10.1016/j.archoralbio.2010.10.017] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2010] [Revised: 10/08/2010] [Accepted: 10/23/2010] [Indexed: 11/23/2022]
Abstract
OBJECTIVE A single Pro-70 to Thr (p.P70T) mutation of amelogenin is known to result in hypomineralised amelogenesis imperfecta (AI). This study aims to test the hypothesis that the given mutation affects the self-assembly of amelogenin molecules and impairs their ability to conduct the growth of apatite crystals. DESIGN Recombinant human full-length wild-type (rh174) and p.P70T mutated amelogenins were analysed using dynamic light scattering (DLS), protein quantification assay and atomic force microscopy (AFM) before and after the binding of amelogenins to hydroxyapatite crystals. The crystal growth modulated by both amelogenins in a dynamic titration system was observed using AFM. RESULTS As compared to rh174 amelogenin, p.P70T mutant displayed significantly increased sizes of the assemblies, higher binding affinity to apatite, and decreased crystal height. CONCLUSION Pro-70 plays an important structural role in the biologically relevant amelogenin self-assembly. The disturbed regularity of amelogenin nanospheres by this single mutation resulted in an increased binding to apatite and inhibited crystal growth.
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50
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Le Norcy E, Kwak SY, Wiedemann-Bidlack FB, Beniash E, Yamakoshi Y, Simmer JP, Margolis HC. Potential role of the amelogenin N-terminus in the regulation of calcium phosphate formation in vitro. Cells Tissues Organs 2011; 194:188-93. [PMID: 21576914 DOI: 10.1159/000324827] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
N-terminal and C-terminal (CT) domains of amelogenin have been shown to be essential for proper enamel formation. Recent studies have also suggested that although the C-terminus plays an apparent role in protein-mineral interactions, other amelogenin structural domains are involved. The objective was to explore the role of the amelogenin N-terminus in the regulation of calcium phosphate formation in vitro. Spontaneous mineralization studies were carried out using the phosphorylated (+P) and nonphosphorylated (-P) N-terminus of the leucine-rich amelogenin peptide (LRAP) that lacks the hydrophilic CT domain. Mineralization progress was monitored via changes in solution pH. Mineral phases formed were characterized using TEM, selected area electron diffraction, and FT-IR. In controls, amorphous calcium phosphate was initially formed and subsequently transformed to randomly oriented hydroxyapatite (HA) plate-like crystals. In contrast to the control, LRAP(+P)-CT stabilized ACP formation for >1 day, while LRAP(-P)-CT accelerated the transformation of ACP to HA but had little effect on crystal shape or orientation. In conclusion, the N-terminal domain found in LRAP, as in amelogenins, appears to have the capacity to interact with forming calcium phosphate mineral phases. Results suggest that the N-terminal domain of amelogenin may play a direct role in early stages of enamel formation.
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Affiliation(s)
- E Le Norcy
- Department of Biomineralization, The Forsyth Institute, Cambridge, Mass., USA
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