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Kawasaki K, Sasagawa I, Mikami M, Nakatomi M, Ishiyama M. Ganoin and acrodin formation on scales and teeth in spotted gar: A vital role of enamelin in the unique process of enamel mineralization. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART B, MOLECULAR AND DEVELOPMENTAL EVOLUTION 2023; 340:455-468. [PMID: 36464775 PMCID: PMC10239528 DOI: 10.1002/jez.b.23183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 11/12/2022] [Accepted: 11/15/2022] [Indexed: 12/12/2022]
Abstract
Gars and bichirs develop scales and teeth with ancient actinopterygian characteristics. Their scale surface and tooth collar are covered with enamel, also known as ganoin, whereas the tooth cap is equipped with an enamel-like tissue, acrodin. Here, we investigated the formation and mineralization of the ganoin and acrodin matrices in spotted gar, and the evolution of the scpp5, ameloblastin (ambn), and enamelin (enam) genes, which encode matrix proteins of ganoin. Results suggest that, in bichirs and gars, all these genes retain structural characteristics of their orthologs in stem actinopterygians, presumably reflecting the presence of ganoin on scales and teeth. During scale formation, Scpp5 and Enam were initially found in the incipient ganoin matrix and the underlying collagen matrix, whereas Ambn was detected mostly in a surface region of the well-developed ganoin matrix. Although collagen is the principal acrodin matrix protein, Scpp5 was detected within the matrix. Similarities in timings of mineralization and the secretion of Scpp5 suggest that acrodin evolved by the loss of the matrix secretory stage of ganoin formation: dentin formation is immediately followed by the maturation stage. The late onset of Ambn secretion during ganoin formation implies that Ambn is not essential for mineral ribbon formation, the hallmark of the enamel matrix. Furthermore, Scpp5 resembles amelogenin that is not important for the initial formation of mineral ribbons in mammals. It is thus likely that the evolution of ENAM was vital to the origin of the unique mineralization process of the enamel matrix.
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Affiliation(s)
- Kazuhiko Kawasaki
- Department of Anthropology, Pennsylvania State University, University Park, Pennsylvania, USA
| | - Ichiro Sasagawa
- Advanced Research Center, School of Life Dentistry at Niigata the Nippon Dental University, Niigata, Japan
| | - Masato Mikami
- Department of Microbiology, School of Life Dentistry at Niigata the Nippon Dental University, Niigata, Japan
| | - Mitsushiro Nakatomi
- Department of Human, Information and Life Sciences, School of Health Sciences, University of Occupational and Environmental Health, Kitakyushu, Japan
| | - Mikio Ishiyama
- Department of Histology, School of Life Dentistry at Niigata the Nippon Dental University, Niigata, Japan
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Athanasiadou D, Carneiro KMM. DNA nanostructures as templates for biomineralization. Nat Rev Chem 2021; 5:93-108. [PMID: 37117611 DOI: 10.1038/s41570-020-00242-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/26/2020] [Indexed: 12/22/2022]
Abstract
Nature uses extracellular matrix scaffolds to organize biominerals into hierarchical structures over various length scales. This has inspired the design of biomimetic mineralization scaffolds, with DNA nanostructures being among the most promising. DNA nanotechnology makes use of molecular recognition to controllably give 1D, 2D and 3D nanostructures. The control we have over these structures makes them attractive templates for the synthesis of mineralized tissues, such as bones and teeth. In this Review, we first summarize recent work on the crystallization processes and structural features of biominerals on the nanoscale. We then describe self-assembled DNA nanostructures and come to the intersection of these two themes: recent applications of DNA templates in nanoscale biomineralization, a crucial process to regenerate mineralized tissues.
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Zhu L, Wang L, Matsuura A, Zhang M, Lu P, Iimura K, Nagata K, Suzuki M. Purification, crystallization and X-ray analysis of Pf-SCP (sarcoplasmic Ca-binding protein), related to storage and transport of calcium in mantle of Pinctada fucata. Protein Expr Purif 2020; 178:105781. [PMID: 33137413 DOI: 10.1016/j.pep.2020.105781] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 10/18/2020] [Indexed: 10/23/2022]
Abstract
Pf-SCP, a 21 kDa protein with two EF-hand motifs and a phosphorylation site, was identified from mantle tissue and binds to calcium ions and transports calcium components from cell to the shell of Pinctada fucata. To reveal the molecular basis of the calcium binding activity of Pf-SCP, we expressed the recombinant protein of full-length Pf-SCP in Escherichia coli. Recombinant Pf-SCP (rPf-SCP) purified by Ni affinity chromatography and size exclusion chromatography appeared as a single band on SDS-PAGE. The circular dichroism spectroscopy showed that the α-helix content decreased when rPf-SCP interacted with both calcium ions and calcium carbonate. Western blotting and immunostaining verified the Pf-SCP expression in the shell and localization most in the mantle epithelial cells. To further understand the structural and functional regulation of Pf-SCP by calcium ions and calcium carbonate, the crystallization experiments of rPf-SCP in the presence of calcium ions were performed. A crystal of rPf-SCP obtained in the presence of calcium ions diffracted X-rays up to a resolution of 1.8 Å. The space group of the crystal is C2 with unit cell parameters of a = 96.828 Å, b = 55.906 Å, c = 102.14 Å and β = 90.009°, indicating that three molecules of rPf-SCP are contained in an asymmetric unit as estimated at the value of the Matthews coefficient. These results suggest that Pf-SCP may play a role in calcium ions transportation and shell mineralization by concentrating calcium ions inside the mantle epithelial cells and interacting with calcium carbonate molecules.
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Affiliation(s)
- Lingxiao Zhu
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Liying Wang
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Akihiro Matsuura
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Mimin Zhang
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Peng Lu
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Kurin Iimura
- Food Department, Department of Home Economics, Japan Women's University, 2-8-1 Mejirodai, Bunkyo-ku, Tokyo, 112-8681, Japan
| | - Koji Nagata
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Michio Suzuki
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
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4
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Abstract
As the hardest tissue formed by vertebrates, enamel represents nature's engineering masterpiece with complex organizations of fibrous apatite crystals at the nanometer scale. Supramolecular assemblies of enamel matrix proteins (EMPs) play a key role as the structural scaffolds for regulating mineral morphology during enamel development. However, to achieve maximum tissue hardness, most organic content in enamel is digested and removed at the maturation stage, and thus knowledge of a structural protein template that could guide enamel mineralization is limited at this date. Herein, by examining a gene-modified mouse that lacked enzymatic degradation of EMPs, we demonstrate the presence of protein nanoribbons as the structural scaffolds in developing enamel matrix. Using in vitro mineralization assays we showed that both recombinant and enamel-tissue-based amelogenin nanoribbons are capable of guiding fibrous apatite nanocrystal formation. In accordance with our understanding of the natural process of enamel formation, templated crystal growth was achieved by interaction of amelogenin scaffolds with acidic macromolecules that facilitate the formation of an amorphous calcium phosphate precursor which gradually transforms into oriented apatite fibers along the protein nanoribbons. Furthermore, this study elucidated that matrix metalloproteinase-20 is a critical regulator of the enamel mineralization as only a recombinant analog of a MMP20-cleavage product of amelogenin was capable of guiding apatite mineralization. This study highlights that supramolecular assembly of the scaffold protein, its enzymatic processing, and its ability to interact with acidic carrier proteins are critical steps for proper enamel development.
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Novel Insights into Regulation of Human Teeth Biomineralization: Deciphering the Role of Post-Translational Modifications in a Tooth Protein Extract. Int J Mol Sci 2019; 20:ijms20164035. [PMID: 31430851 PMCID: PMC6720696 DOI: 10.3390/ijms20164035] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 08/16/2019] [Accepted: 08/17/2019] [Indexed: 12/11/2022] Open
Abstract
The importance of whole protein extracts from different types of human teeth in modulating the process of teeth biomineralization is reported. There are two crucial features in protein molecules that result in efficient teeth biomineralization. Firstly, the unique secondary structure characteristics within these proteins i.e. the exclusive presence of a large amount of intrinsic disorder and secondly, the presence of post-translational modifications (PTM) like phosphorylation and glycosylation within these protein molecules. The present study accesses the structural implications of PTMs in the tooth proteins through scanning electron microscopy and transmission electron microscopy. The deglycosylated/dephosphorylated protein extracts failed to form higher-order mineralization assemblies. Furthermore, through nanoparticle tracking analysis (NTA) we have shown that dephosphorylation and deglycosylation significantly impact the biomineralization abilities of the protein extract and resulted in smaller sized clusters. Hence, we propose these post-translational modifications are indispensable for the process of teeth biomineralization. In addition to basic science, this study would be worth consideration while designing of biomimetics architecture for an efficient peptide-based teeth remineralization strategy.
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Tao J, Fijneman A, Wan J, Prajapati S, Mukherjee K, Fernandez-Martinez A, Moradian-Oldak J, De Yoreo JJ. Control of Calcium Phosphate Nucleation and Transformation through Interactions of Enamelin and Amelogenin Exhibits the "Goldilocks Effect". CRYSTAL GROWTH & DESIGN 2018; 18:7391-7400. [PMID: 32280310 PMCID: PMC7152501 DOI: 10.1021/acs.cgd.8b01066] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Although amelogenin comprises the vast majority of the matrix that templates calcium phosphate nucleation during enamel formation, other proteins, particularly enamelin, are also known to play an important role in the formation of enamel's intricate architecture. However, there is little understanding of the interplay between amelogenin and enamelin in controlling processes of mineral nucleation and growth. Here, we used an in vitro model to investigate the impact of enamelin interaction with amelogenin on calcium phosphate nucleation for a range of enamelin-to-amelogenin ratios. We found that amelogenin alone is a weak promoter of nucleation, but addition of enamelin enhanced nucleation rates in a highly nonlinear, nonmonotonic manner reaching a sharp maximum at a ratio of 1:50 enamelin/amelogenin. We provide a phenomenological model to explain this effect that assumes only isolated enamelin proteins can act as sites of enhanced nucleation, while enamelin oligomers cannot. Even when interaction is random, the model reproduces the observed behavior, suggesting a simple means to tightly control the timing and extent of nucleation and phase transformation by amelogenin and enamelin.
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Affiliation(s)
- Jinhui Tao
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Andreas Fijneman
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
- Laboratory of Materials and Interface Chemistry and Center of Multiscale Electron Microscopy, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Jiaqi Wan
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Saumya Prajapati
- Univeristy of Southern California, Center for Craniofacial Molecular Biology, Los Angeles, California 90033, United States
| | - Kaushik Mukherjee
- Univeristy of Southern California, Center for Craniofacial Molecular Biology, Los Angeles, California 90033, United States
| | | | - Janet Moradian-Oldak
- Univeristy of Southern California, Center for Craniofacial Molecular Biology, Los Angeles, California 90033, United States
- Corresponding Authors .,
| | - James J. De Yoreo
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
- Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98195, United States
- Corresponding Authors .,
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Ramachandran A, He K, Huang CC, Shahbazian-Yassar R, Shokuhfar T, George A. TRIP-1 in the extracellular matrix promotes nucleation of calcium phosphate polymorphs. Connect Tissue Res 2018; 59:13-19. [PMID: 29745814 DOI: 10.1080/03008207.2018.1424146] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
In search for bone and dentin extracellular matrix (ECM) proteins, transforming growth factor beta receptor II interacting protein 1 (TRIP-1) was identified as a novel protein synthesized by osteoblasts and odontoblasts and exported to the ECM. TRIP-1 is a WD-40 (WD is Tryptophan-Aspartic acid dipeptide) protein that has been well recognized for its physiological role in the endoplasmic reticulum (ER). In the ER, TRIP-1 functions as an essential subunit of eukaryotic elongation initiation factor 3 and is involved in the protein translational machinery. Recently, we reported that TRIP-1 is localized in the ECM of bone and dentin. In this study, we demonstrate that varying concentrations of TRIP-1 can participate in the nucleation of calcium phosphate polymorphs. Nucleation studies performed with high calcium and phosphate concentration demonstrated that recombinant TRIP-1 could orchestrate the formation of hydroxyapatite crystals. Nucleation experiments performed on demineralized and deproteinized dentin wafer under physiological conditions and subsequent transmission electron microscope analysis of the deposits at the end of 7 and 14 days showed that TRIP-1 promoted the deposition of calcium phosphate mineral aggregates in the gap-overlap region of type I collagen. Taken together, we provide mechanistic insight into the role of this intracellular protein in matrix mineralization.
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Affiliation(s)
- Amsaveni Ramachandran
- a Brodie Tooth Development Genetics & Regenerative Medicine Research Laboratory, Department of Oral Biology , University of Illinois at Chicago , Chicago , IL , USA
| | - Kun He
- b Department of Mechanical and Industrial Engineering , University of Illinois at Chicago , Chicago , IL , USA
| | - Chun-Chieh Huang
- a Brodie Tooth Development Genetics & Regenerative Medicine Research Laboratory, Department of Oral Biology , University of Illinois at Chicago , Chicago , IL , USA
| | - Reza Shahbazian-Yassar
- b Department of Mechanical and Industrial Engineering , University of Illinois at Chicago , Chicago , IL , USA
| | - Tolou Shokuhfar
- c Department of Bioengineering , University of Illinois at Chicago , Chicago , IL , USA
| | - Anne George
- a Brodie Tooth Development Genetics & Regenerative Medicine Research Laboratory, Department of Oral Biology , University of Illinois at Chicago , Chicago , IL , USA
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Elsharkawy S, Mata A. Hierarchical Biomineralization: from Nature's Designs to Synthetic Materials for Regenerative Medicine and Dentistry. Adv Healthc Mater 2018; 7:e1800178. [PMID: 29943412 DOI: 10.1002/adhm.201800178] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 04/08/2018] [Indexed: 12/28/2022]
Abstract
Biomineralization is a highly dynamic, yet controlled, process that many living creatures employ to develop functional tissues such as tooth enamel, bone, and others. A major goal in materials science is to create bioinspired functional structures based on the precise organization of building blocks across multiple length scales. Therefore, learning how nature has evolved to use biomineralization could inspire new ways to design and develop synthetic hierarchical materials with enhanced functionality. Toward this goal, this review dissects the current understanding of structure-function relationships of dental enamel and bone using a materials science perspective and discusses a wide range of synthetic technologies that aim to recreate their hierarchical organization and functionality. Insights into how these strategies could be applied for regenerative medicine and dentistry are also provided.
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Affiliation(s)
- Sherif Elsharkawy
- Institute of Bioengineering; Queen Mary University of London; London E1 4NS UK
- School of Engineering and Materials Science; Queen Mary University of London; London E1 4NS UK
- Institute of Dentistry; Barts and The London School of Medicine and Dentistry; Queen Mary University of London; London E1 4NS UK
| | - Alvaro Mata
- Institute of Bioengineering; Queen Mary University of London; London E1 4NS UK
- School of Engineering and Materials Science; Queen Mary University of London; London E1 4NS UK
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Protein disorder–order interplay to guide the growth of hierarchical mineralized structures. Nat Commun 2018; 9:2145. [PMID: 29858566 PMCID: PMC5984621 DOI: 10.1038/s41467-018-04319-0] [Citation(s) in RCA: 84] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Accepted: 04/18/2018] [Indexed: 01/05/2023] Open
Abstract
A major goal in materials science is to develop bioinspired functional materials based on the precise control of molecular building blocks across length scales. Here we report a protein-mediated mineralization process that takes advantage of disorder–order interplay using elastin-like recombinamers to program organic–inorganic interactions into hierarchically ordered mineralized structures. The materials comprise elongated apatite nanocrystals that are aligned and organized into microscopic prisms, which grow together into spherulite-like structures hundreds of micrometers in diameter that come together to fill macroscopic areas. The structures can be grown over large uneven surfaces and native tissues as acid-resistant membranes or coatings with tuneable hierarchy, stiffness, and hardness. Our study represents a potential strategy for complex materials design that may open opportunities for hard tissue repair and provide insights into the role of molecular disorder in human physiology and pathology. There is evidence that disordered proteins play a role in the mineralization process. Here, the authors report on the development of elastin-like recombinant protein membranes using disordered-ordered interplay to investigate and guide mineralization.
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10
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Mazumder P, Prajapati S, Lokappa SB, Gallon V, Moradian-Oldak J. Analysis of co-assembly and co-localization of ameloblastin and amelogenin. Front Physiol 2014; 5:274. [PMID: 25120489 PMCID: PMC4110739 DOI: 10.3389/fphys.2014.00274] [Citation(s) in RCA: 20] [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: 05/22/2014] [Accepted: 07/07/2014] [Indexed: 12/17/2022] Open
Abstract
Epithelially-derived ameloblasts secrete extracellular matrix proteins including amelogenin, enamelin, and ameloblastin. Complex intermolecular interactions among these proteins are believed to be important in controlling enamel formation. Here we provide in vitro and in vivo evidence of co-assembly and co-localization of ameloblastin with amelogenin using both biophysical and immunohistochemical methods. We performed co-localization studies using immunofluorescence confocal microscopy with paraffin-embedded tissue sections from mandibular molars of mice at 1, 5, and 8 days of age. Commercially-available ameloblastin antibody (M300) against mouse ameloblastin residues 107-407 and an antibody against full-length recombinant mouse (rM179) amelogenin were used. Ameloblastin-M300 clearly reacted along the secretory face of ameloblasts from days 1-8. Quantitative co-localization was analyzed (QCA) in several configurations by choosing appropriate regions of interest (ROIs). Analysis of ROIs along the secretory face of ameloblasts revealed that at day 1, very high percentages of both the ameloblastin and amelogenin co-localized. At day 8 along the ameloblast cells the percentage of co-localization remained high for the ameloblastin whereas co-localization percentage was reduced for amelogenin. Analysis of the entire thickness on day 8 revealed no significant co-localization of amelogenin and ameloblastin. With the progress of amelogenesis and ameloblastin degradation, there was a segregation of ameloblastin and co-localization with the C-terminal region decreased. CD spectra indicated that structural changes in ameloblastin occurred upon addition of amelogenin. Our data suggest that amelogenin-ameloblastin complexes may be the functional entities at the early stage of enamel mineralization.
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Affiliation(s)
| | | | | | | | - Janet Moradian-Oldak
- Division of Biomedical Sciences, Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern CaliforniaLos Angeles, CA, USA
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Gallon V, Chen L, Yang X, Moradian-Oldak J. Localization and quantitative co-localization of enamelin with amelogenin. J Struct Biol 2013; 183:239-49. [PMID: 23563189 PMCID: PMC3737400 DOI: 10.1016/j.jsb.2013.03.014] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Revised: 03/11/2013] [Accepted: 03/25/2013] [Indexed: 02/07/2023]
Abstract
Enamelin and amelogenin are vital proteins in enamel formation. The cooperative function of these two proteins controls crystal nucleation and morphology in vitro. We quantitatively analyzed the co-localization between enamelin and amelogenin by confocal microscopy and using two antibodies, one raised against a sequence in the porcine 32 kDa enamelin region and the other raised against full-length recombinant mouse amelogenin. We further investigated the interaction of the porcine 32 kDa enamelin and recombinant amelogenin using immuno-gold labeling. This study reports the quantitative co-localization results for postnatal days 1-8 mandibular mouse molars. We show that amelogenin and enamelin are secreted into the extracellular matrix on the cuspal slopes of the molars at day 1 and that secretion continues to at least day 8. Quantitative co-localization analysis (QCA) was performed in several different configurations using large (45 μm height, 33 μm width) and small (7 μm diameter) regions of interest to elucidate any patterns. Co-localization patterns in day 8 samples revealed that enamelin and amelogenin co-localize near the secretory face of the ameloblasts and appear to be secreted approximately in a 1:1 ratio. The degree of co-localization decreases as the enamel matures, both along the secretory face of ameloblasts and throughout the entire thickness of the enamel. Immuno-reactivity against enamelin is concentrated along the secretory face of ameloblasts, supporting the theory that this protein together with amelogenin is intimately involved in mineral induction at the beginning of enamel formation.
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Affiliation(s)
- Victoria Gallon
- Center for Craniofacial Molecular Biology, University of Southern California, Herman Ostrow School of Dentistry, Los Angeles, CA 90033, USA
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Abstract
The structures and interactions among macromolecules in the enamel extracellular matrix play vital roles in regulating hydroxyapatite crystal nucleation, growth, and maturation. We used dynamic light scattering (DLS), circular dichroism (CD), fluorescence spectroscopy, and transmission electron microscopy (TEM) to investigate the association of amelogenin and the 32-kDa enamelin, at physiological pH 7.4, in phosphate-buffered saline (PBS). The self-assembly behavior of amelogenin (rP148) was altered following addition of the 32-kDa enamelin. Dynamic light scattering revealed a trend for a decrease in aggregate size in the solution following the addition of enamelin to amelogenin. A blue-shift and intensity increase of the ellipticity minima of rP148 in the CD spectra upon the addition of the 32-kDa enamelin, suggest a direct interaction between the two proteins. In the fluorescence spectra, the maximum emission of rP148 was red-shifted from 335 to 341 nm with a marked intensity increase in the presence of enamelin as a result of complexation of the two proteins. In agreement with DLS data, TEM imaging showed that the 32-kDa enamelin dispersed the amelogenin aggregates into oligomeric particles and stabilized them. Our study provides novel insights into understanding the possible cooperation between enamelin and amelogenin in macromolecular co-assembly and in controlling enamel mineral formation.
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Affiliation(s)
- Xiudong Yang
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, CA 90033, USA
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Hybrid hydrogels self-assembled from graft copolymers containing complementary β-sheets as hydroxyapatite nucleation scaffolds. Biomaterials 2011; 32:5341-53. [PMID: 21549421 DOI: 10.1016/j.biomaterials.2011.04.014] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Accepted: 04/05/2011] [Indexed: 11/20/2022]
Abstract
A biomimetic material that can assist bone tissue regeneration was proposed. A bone scaffold based on a hybrid hydrogel self-assembled from N-(2-hydroxypropyl)methacrylamide (HPMA) copolymers grafted with complementary β-sheet peptides was designed. Investigation of self-assembly by circular dichroism spectroscopy suggested that hydrogel formation was triggered through association of the complementary β-sheet motifs. Congo Red and thioflavin T binding, as well as transmission electron microscopy confirmed the formation of a fibril network. Besides mimicking the natural bone extracellular matrix and maintaining preosteoblast cells viability, this hydrogel, as shown by scanning electron microscopy and Fourier transform infrared spectroscopy, provided surfaces characterized by epitaxy that favored hydroxyapatite-like crystal nucleation and growth potentially beneficial for biointegration.
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Fan D, Iijima M, Bromley KM, Yang X, Mathew S, Moradian-Oldak J. The cooperation of enamelin and amelogenin in controlling octacalcium phosphate crystal morphology. Cells Tissues Organs 2011; 194:194-8. [PMID: 21525716 DOI: 10.1159/000324208] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Enamel matrix proteins, including the most abundant amelogenin and lesser amounts of enamelin, ameloblastin, and proteinases, play vital roles in controlling crystal nucleation and growth during enamel formation. The cooperative action between amelogenin and the 32-kDa enamelin is critical to regulating the growth morphology of octacalcium phosphate crystals. Using biophysical methods, we investigated the interaction between the 32-kDa enamelin and recombinant pig amelogenin 148 (rP148) at pH 6.5 in phosphate-buffered saline (PBS). Dynamic light scattering results showed a trend of increasing particle size in the mixture with the addition of enamelin to amelogenin. Upon addition of the 32-kDa enamelin, the shift and intensity decrease in the ellipticity minima of rP148 in the circular dichroism spectra of rP148 illustrated a direct interaction between the 2 proteins. In the fluorescence spectra, the maximum emission of rP148 was blue shifted from 335 to 333 nm in the presence of enamelin as a result of complexation of the 2 proteins. Our results demonstrate that the 32-kDa enamelin has a close association with amelogenin at pH 6.5 in PBS buffer. Our present study provides novel insights into the possible cooperation between enamelin and amelogenin in macromolecular coassembly and in controlling enamel mineral formation.
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Affiliation(s)
- Daming Fan
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, CA, USA
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15
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Iijima M, Fan D, Bromley KM, Sun Z, Moradian-Oldak J. Tooth enamel proteins enamelin and amelogenin cooperate to regulate the growth morphology of octacalcium phosphate crystals. CRYSTAL GROWTH & DESIGN 2010; 10:4815-4822. [PMID: 21483648 PMCID: PMC3072691 DOI: 10.1021/cg100696r] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
To examine the hypothetical cooperative role of enamelin and amelogenin in controlling the growth morphology of enamel crystals in the post-secretory stage, we applied a cation selective membrane system for the growth of octacalcium phosphate (OCP) in the truncated recombinant porcine amelogenin (rP148) with and without the 32kDa enamelin fragment. Enamelin alone inhibited the growth in the c-axis direction more than rP148, yielding OCP crystals with the smallest aspect ratio of all conditions tested. When enamelin was added to the amelogenin "gel-like matrix", the inhibitory action of the protein mixture on the growth of OCP in the c-axis direction was diminished, while that in the b-axis direction was increased. As a result, the length to width ratio (aspect ratio) of OCP crystal was markedly increased. Addition of enamelin to amelogenin enhanced the potential of amelogenin to stabilize the amorphous calcium phosphate (ACP) transient phase. The ratio of enamelin and amelogenin was crucial for stabilization of ACP and the growth of OCP crystals with larger aspect ratio. The cooperative regulatory action of enamelin and amelogenin was attained, presumably, through co-assembling of enamelin and amelogenin. These results have important implications in understanding the growth mechanism of enamel crystals with large aspect ratio.
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Affiliation(s)
- Mayumi Iijima
- Dental Materials Science, Asahi University School of Dentistry, Gifu, Japan
| | - Daming Fan
- Center for Craniofacial Molecular Biology, University of Southern California, LA, CA, USA
| | - Keith M. Bromley
- Center for Craniofacial Molecular Biology, University of Southern California, LA, CA, USA
| | - Zhi Sun
- Center for Craniofacial Molecular Biology, University of Southern California, LA, CA, USA
| | - Janet Moradian-Oldak
- Center for Craniofacial Molecular Biology, University of Southern California, LA, CA, USA
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Simmer JP, Papagerakis P, Smith CE, Fisher DC, Rountrey AN, Zheng L, Hu JCC. Regulation of dental enamel shape and hardness. J Dent Res 2010; 89:1024-38. [PMID: 20675598 DOI: 10.1177/0022034510375829] [Citation(s) in RCA: 157] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Epithelial-mesenchymal interactions guide tooth development through its early stages and establish the morphology of the dentin surface upon which enamel will be deposited. Starting with the onset of amelogenesis beneath the future cusp tips, the shape of the enamel layer covering the crown is determined by five growth parameters: the (1) appositional growth rate, (2) duration of appositional growth (at the cusp tip), (3) ameloblast extension rate, (4) duration of ameloblast extension, and (5) spreading rate of appositional termination. Appositional growth occurs at a mineralization front along the ameloblast distal membrane in which amorphous calcium phosphate (ACP) ribbons form and lengthen. The ACP ribbons convert into hydroxyapatite crystallites as the ribbons elongate. Appositional growth involves a secretory cycle that is reflected in a series of incremental lines. A potentially important function of enamel proteins is to ensure alignment of successive mineral increments on the tips of enamel ribbons deposited in the previous cycle, causing the crystallites to lengthen with each cycle. Enamel hardens in a maturation process that involves mineral deposition onto the sides of existing crystallites until they interlock with adjacent crystallites. Neutralization of acidity generated by hydroxyapatite formation is a key part of the mechanism. Here we review the growth parameters that determine the shape of the enamel crown as well as the mechanisms of enamel appositional growth and maturation.
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Affiliation(s)
- J P Simmer
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, 1011 N. University, Ann Arbor, MI 48109-1078, USA
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Yusifov T, Javaherian AD, Pantazis A, Gandhi CS, Olcese R. The RCK1 domain of the human BKCa channel transduces Ca2+ binding into structural rearrangements. ACTA ACUST UNITED AC 2010; 136:189-202. [PMID: 20624858 PMCID: PMC2912072 DOI: 10.1085/jgp.200910374] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Large-conductance voltage- and Ca2+-activated K+ (BKCa) channels play a fundamental role in cellular function by integrating information from their voltage and Ca2+ sensors to control membrane potential and Ca2+ homeostasis. The molecular mechanism of Ca2+-dependent regulation of BKCa channels is unknown, but likely relies on the operation of two cytosolic domains, regulator of K+ conductance (RCK)1 and RCK2. Using solution-based investigations, we demonstrate that the purified BKCa RCK1 domain adopts an α/β fold, binds Ca2+, and assembles into an octameric superstructure similar to prokaryotic RCK domains. Results from steady-state and time-resolved spectroscopy reveal Ca2+-induced conformational changes in physiologically relevant [Ca2+]. The neutralization of residues known to be involved in high-affinity Ca2+ sensing (D362 and D367) prevented Ca2+-induced structural transitions in RCK1 but did not abolish Ca2+ binding. We provide evidence that the RCK1 domain is a high-affinity Ca2+ sensor that transduces Ca2+ binding into structural rearrangements, likely representing elementary steps in the Ca2+-dependent activation of human BKCa channels.
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Affiliation(s)
- Taleh Yusifov
- Division of Molecular Medicine, Department of Anesthesiology, David Geffen School of Medicine at University of California, Los Angeles, CA 90095, USA
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Chan HC, Mai L, Oikonomopoulou A, Chan HL, Richardson AS, Wang SK, Simmer JP, Hu JCC. Altered enamelin phosphorylation site causes amelogenesis imperfecta. J Dent Res 2010; 89:695-9. [PMID: 20439930 DOI: 10.1177/0022034510365662] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Defects in the enamelin gene (ENAM) cause amelogenesis imperfecta (AI). Our objective was to identify the genetic etiology of enamel hypoplasia in a Caucasian proband. Our hypothesis was that ENAM was defective. The proband and his father have an AG insertion (g.13185_13186insAG; p.422FsX448) in ENAM previously identified in AI kindreds from Slovenia and Turkey. The proband, his brother, and his mother have a novel missense mutation (g.12573C>T) that substitutes leucine for a phosphorylated serine (p.S216L) in the 32-kDa enamelin cleavage product. In this family, a defect in one ENAM allele caused minor pitting or localized enamel hypoplasia, whereas defects in both alleles caused severe enamel malformations, with little or no mineral covering dentin. Ser(216) is one of two serines on the 32-kDa enamelin that is phosphorylated by Golgi casein kinase and is thought to mediate calcium binding. We propose that phosphorylation of enamelin is critical for its function.
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Affiliation(s)
- H-C Chan
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, 1011 N. University, Ann Arbor, MI 48109-1078, USA
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Al-Hashimi N, Sire JY, Delgado S. Evolutionary analysis of mammalian enamelin, the largest enamel protein, supports a crucial role for the 32-kDa peptide and reveals selective adaptation in rodents and primates. J Mol Evol 2010; 69:635-56. [PMID: 20012271 DOI: 10.1007/s00239-009-9302-x] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2009] [Accepted: 11/06/2009] [Indexed: 12/20/2022]
Abstract
Enamelin (ENAM) plays an important role in the mineralization of the forming enamel matrix. We have performed an evolutionary analysis of mammalian ENAM to identify highly conserved residues or regions that could have important function (selective pressure), to predict mutations that could be associated with amelogenesis imperfecta in humans, and to identify possible adaptive evolution of ENAM during 200 million years ago of mammalian evolution. In order to fulfil these objectives, we obtained 36-ENAM sequences that are representative of the mammalian lineages. Our results show a remarkably high conservation pattern in the region of the 32-kDa fragment of ENAM, especially its phosphorylation, glycosylation, and proteolytic sites. In primates and rodents we also identified several sites under positive selection, which could indicate recent evolutionary changes in ENAM function. Furthermore, the analysis of the unusual signal peptide provided new insights on the possible regulation of ENAM secretion, a hypothesis that should be tested in the near future. Taken together, these findings improve our understanding of ENAM evolution and provide new information that would be useful for further investigation of ENAM function as well as for the validation of mutations leading to amelogenesis imperfecta.
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Affiliation(s)
- Nawfal Al-Hashimi
- Université Pierre et Marie Curie, UMR 7138-Systématique, Adaptation, Evolution, Case 5, 7 Quai Saint-Bernard, Bâtiment A, 4e étage, 75005, Paris, France
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Fan D, Du C, Sun Z, Lakshminarayanan R, Moradian-Oldak J. In vitro study on the interaction between the 32 kDa enamelin and amelogenin. J Struct Biol 2009; 166:88-94. [PMID: 19263522 DOI: 10.1016/j.jsb.2009.01.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Enamel extracelluar matrix components play vital roles in controlling crystal nucleation and growth during enamel formation. We investigated the interaction between the 32 kDa enamelin fragment and amelogenin using immunochemical and biophysical methods. Immunoprecipitation studies revealed that the 32 kDa enamelin and amelogenin eluted together from a Protein A column. Dynamic light scattering results showed that the 32 kDa enamelin had a profound effect on amelogenin assembly at pH 8.0, causing partial dissociation of the nanospheres, in a dose-dependent manner. The appearance of an isodichroic point and the shifting and intensity decrease of the ellipticity minima in the circular dichroism spectra of amelogenin following the addition of the 32 kDa enamelin were indicative of conformational changes in amelogenin and of a direct interaction between the two macromolecules. Our results collectively demonstrate that the 32 kDa enamelin has a direct interaction with amelogenin in vitro. Our current studies provide novel insights into understanding possible cooperation between enamelin and amelogenin in macromolecular self-assembly and in controlling enamel mineral formation.
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Affiliation(s)
- Daming Fan
- University of Southern California, School of Dentistry, Center for Craniofacial Molecular Biology, 2250 Alcazar Street CSA 103, Los Angeles, CA 90033, USA
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