1
|
Diekwisch TGH. Alan Fincham and the era of enamel protein Biochemistry. Front Physiol 2022; 13:1071265. [PMID: 36545279 PMCID: PMC9760720 DOI: 10.3389/fphys.2022.1071265] [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: 10/16/2022] [Accepted: 11/21/2022] [Indexed: 12/12/2022] Open
Abstract
Enamel research experienced an unprecedented period of growth during the latter part of the 20th century until today. This growth is in part due to the contributions of a number of iconic scientists such as Alan G. Fincham, the focus of the present review. Alan was involved in many of the seminal discoveries of this time, including the identification of the critical amelogenin peptides TRAP and LRAP, the determination of the amelogenin amino acid sequence, the identification of the sole serin-16 phosphorylation site, and the amelogenin nanosphere theory. Alan was also a superb mentor to graduate students and others. His experience and leadership related to problem-based learning greatly affected predoctoral dental education at the University of Southern California and in the United States.
Collapse
|
2
|
Tang S, Dong Z, Ke X, Luo J, Li J. Advances in biomineralization-inspired materials for hard tissue repair. Int J Oral Sci 2021; 13:42. [PMID: 34876550 PMCID: PMC8651686 DOI: 10.1038/s41368-021-00147-z] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2021] [Revised: 10/31/2021] [Accepted: 11/02/2021] [Indexed: 12/24/2022] Open
Abstract
Biomineralization is the process by which organisms form mineralized tissues with hierarchical structures and excellent properties, including the bones and teeth in vertebrates. The underlying mechanisms and pathways of biomineralization provide inspiration for designing and constructing materials to repair hard tissues. In particular, the formation processes of minerals can be partly replicated by utilizing bioinspired artificial materials to mimic the functions of biomolecules or stabilize intermediate mineral phases involved in biomineralization. Here, we review recent advances in biomineralization-inspired materials developed for hard tissue repair. Biomineralization-inspired materials are categorized into different types based on their specific applications, which include bone repair, dentin remineralization, and enamel remineralization. Finally, the advantages and limitations of these materials are summarized, and several perspectives on future directions are discussed.
Collapse
Affiliation(s)
- Shuxian Tang
- College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu, PR China
| | - Zhiyun Dong
- College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu, PR China
| | - Xiang Ke
- College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu, PR China
| | - Jun Luo
- College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu, PR China.
| | - Jianshu Li
- College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu, PR China.
- Med-X Center for Materials, Sichuan University, Chengdu, PR China.
| |
Collapse
|
3
|
Abstract
Enamel is a hard nanocomposite bioceramic with significant resilience that protects the mammalian tooth from external physical and chemical damages. The remarkable mechanical properties of enamel are associated with its hierarchical structural organization and its thorough connection with underlying dentin. This dynamic mineralizing system offers scientists a wealth of information that allows the study of basic principels of organic matrix-mediated biomineralization and can potentially be utilized in the fields of material science and engineering for development and design of biomimetic materials. This chapter will provide a brief overview of enamel hierarchical structure and properties and the process and stages of amelogenesis. Particular emphasis is given to current knowledge of extracellular matrix protein and proteinases, and the structural chemistry of the matrix components and their putative functions. The chapter will conclude by discussing the potential of enamel for regrowth.
Collapse
Affiliation(s)
- Janet Moradian-Oldak
- Center for Craniofacial Molecular Biology, Ostrow School of Dentistry, University of Southern California, Los Angeles, CA 90033, USA.
| |
Collapse
|
4
|
Chen CL, Bromley KM, Moradian-Oldak J, DeYoreo JJ. In situ AFM study of amelogenin assembly and disassembly dynamics on charged surfaces provides insights on matrix protein self-assembly. J Am Chem Soc 2011; 133:17406-13. [PMID: 21916473 PMCID: PMC3427831 DOI: 10.1021/ja206849c] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Because self-assembly of matrix proteins is a key step in hard tissue mineralization, developing an understanding of the assembly pathways and underlying mechanisms is likely to be important for successful hard tissue engineering. While many studies of matrix protein assembly have been performed on bulk solutions, in vivo these proteins are likely to be in contact with charged biological surfaces composed of lipids, proteins, or minerals. Here we report the results of an in situ atomic force microscopy (AFM) study of self-assembly by amelogenin--the principal protein of the extracellular matrix in developing enamel--in contact with two different charged substrates: hydrophilic negatively charged bare mica and positively charged 3-aminopropyl triethoxysilane (APS) silanized mica. First we demonstrate an AFM-based protocol for determining the size of both amelogenin monomers and oligomers. Using this protocol, we find that, although amelogenin exists primarily as ~26 nm in diameter nanospheres in bulk solution at a pH of 8.0 studied by dynamic light scattering, it behaves dramatically differently upon interacting with charged substrates at the same pH and exhibits complex substrate-dependent assembly pathways and dynamics. On positively charged APS-treated mica surfaces, amelogenin forms a relatively uniform population of decameric oligomers, which then transform into two main populations: higher-order assemblies of oligomers and amelogenin monomers, while on negatively charged bare mica surfaces, it forms a film of monomers that exhibits tip-induced desorption and patterning. The present study represents a successful attempt to identify the size of amelogenin oligomers and to directly monitor assembly and disassembly dynamics on surfaces. The findings have implications for amelogenin-controlled calcium phosphate mineralization in vitro and may offer new insights into in vivo self-assembly of matrix proteins as well as their control over hard tissue formation.
Collapse
Affiliation(s)
- Chun-Long Chen
- The Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, United States
| | - Keith M. Bromley
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, CA 90033, United States
| | - Janet Moradian-Oldak
- Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, CA 90033, United States
| | - James J. DeYoreo
- The Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, United States
| |
Collapse
|
5
|
Yang X, Sun Z, Ma R, Fan D, Moradian-Oldak J. Amelogenin "nanorods" formation during proteolysis by Mmp-20. J Struct Biol 2011; 176:220-8. [PMID: 21840397 PMCID: PMC3185149 DOI: 10.1016/j.jsb.2011.07.016] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2011] [Revised: 07/28/2011] [Accepted: 07/29/2011] [Indexed: 11/19/2022]
Abstract
Amelogenin is cleaved by enamelysin (Mmp-20) soon after its secretion, and the cleavage products accumulate in specific locations during enamel formation, suggesting that parent amelogenin proteolysis is necessary for activating its functions. To investigate the precise roles of Mmp-20 and its influence on the assembly of amelogenin, an in vitro enzymatic digestion process mimicking the initial stages of amelogenin proteolysis was investigated at near-physiological conditions using recombinant porcine amelogenin (rP172) and enamelysin. Hierarchically organized nanorod structures formed during different digestion stages were detected by TEM. At the earliest stage, uniformly dispersed parent amelogenin spherical particles, mixed with some darker stained smaller spheres, and accompanying elongated chain-like nanostructures were observed. Cylindrical nanorods, which appeared to be the result of tight assembly of thin subunit cylindrical discs with thicknesses ranging from ∼2.5 to ∼6.0nm, were formed after an hour of proteolysis. These subunit building blocks stacked to form nanorods with maximum length of ∼100nm. With the production of more cleavage products, additional morphologies spontaneously evolved from the cylindrical nanorods. Larger ball-like aggregates ultimately formed at the end of proteolysis. The uniform spherical particles, nanorods, morphological patterns evolved from nanorods, and globular aggregated microstructures were successively formed by means of co-assembly of amelogenin and its cleavage products during a comparatively slow proteolysis process. We propose that, following the C-terminal cleavage of amelogenin, co-assembly with its fragments leads to formation of nanorod structures whose properties eventually dictate the super-structural organization of enamel matrix, controlling the elongated growth of enamel apatite crystals.
Collapse
Affiliation(s)
- Xiudong Yang
- Center for Craniofacial Molecular Biology, University of Southern California, Herman Ostrow School of Dentistry, 2250 Alcazar St., Los Angeles, CA 90033, USA
| | | | | | | | | |
Collapse
|
6
|
Uskoković V. Prospects and Pits on the Path of Biomimetics: The case of tooth enamel. JOURNAL OF BIOMIMETICS, BIOMATERIALS, AND TISSUE ENGINEERING 2010; 8:45-78. [PMID: 26877723 PMCID: PMC4752007 DOI: 10.4028/www.scientific.net/jbbte.8.45] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This review presents a discourse on challenges in understanding and imitating the process of amelogenesis in vitro on the molecular scale. In light of the analysis of imitation of the growth of dental enamel, it also impends on the prospects and potential drawbacks of the biomimetic approach in general. As the formation of enamel proceeds with the protein matrix guiding the crystal growth, while at the same time conducting its own degradation and removal, it is argued that three aspects of amelogenesis need to be induced in parallel: a) crystal growth; b) protein assembly; c) proteolytic degradation. A particular emphasis is therefore placed on ensuring conditions for proteolysis-coupled protein-guided crystallization to occur. Discussed are structural and functional properties of the protein species involved in amelogenesis, mainly amelogenin and enamelysin, the main protein and the protease of the developing enamel matrix, respectively. A model of enamel growth based on controlled delivery of constituent ions or crystalline or amorphous building blocks by means of amelogenin is proposed. The importance of high viscosity of the enamel matrix and a more intricate role that water may play in such a gelatinous medium are also touched upon. The tendency of amelogenin to self-assemble into fibrous and rod-shaped morphologies is considered as potentially important in explaining the formation of elongated apatite crystals. The idea that a preassembling protein matrix serves as a template for the uniaxial growth of apatite crystals in enamel is finally challenged with the one based on co-assembly of the protein and the mineral phases.
Collapse
Affiliation(s)
- Vuk Uskoković
- Division of Biomaterials and Bioengineering, University of California, San Francisco, USA,
| |
Collapse
|
7
|
Aichmayer B, Wiedemann-Bidlack FB, Gilow C, Simmer JP, Yamakoshi Y, Emmerling F, Margolis HC, Fratzl P. Amelogenin nanoparticles in suspension: deviations from spherical shape and pH-dependent aggregation. Biomacromolecules 2010; 11:369-76. [PMID: 20038137 PMCID: PMC2817559 DOI: 10.1021/bm900983b] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
It is well-known that amelogenin self-assembles to form nanoparticles, usually referred to as amelogenin nanospheres, despite the fact that not much is known about their actual shape in solution. In the current paper, we combine SAXS and DLS to study the three-dimensional shape of the recombinant amelogenins rP172 and rM179. Our results show for the first time that amelogenins build oblate nanoparticles in suspension using experimental approaches that do not require the proteins to be in contact with a support material surface. The SAXS studies give evidence for the existence of isolated amelogenin nano-oblates with aspect ratios in the range of 0.45-0.5 at pH values higher than pH 7.2 and show an aggregation of these nano-oblates at lower pH values. The role of the observed oblate shape in the formation of chain-like structures at physiological conditions is discussed as a key factor in the biomineralization of dental enamel.
Collapse
Affiliation(s)
- Barbara Aichmayer
- Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany.
| | | | | | | | | | | | | | | |
Collapse
|
8
|
Yang X, Wang L, Qin Y, Sun Z, Henneman ZJ, Moradian-Oldak J, Nancollas GH. How amelogenin orchestrates the organization of hierarchical elongated microstructures of apatite. J Phys Chem B 2010; 114:2293-300. [PMID: 20104924 PMCID: PMC2848079 DOI: 10.1021/jp910219s] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Amelogenin (Amel) accelerates the nucleation of hydroxyapatite (HAP) in supersaturated solutions of calcium phosphate (Ca-P), shortening the induction time (delay period), under near-physiological conditions of pH, temperature, and ionic strength. Hierarchically organized Amel and amorphous calcium phosphate (ACP) nanorod microstructures are formed involving a coassembly of Amel-ACP particles at low supersaturations and low protein concentrations in a slow, well-controlled, constant composition (CC) crystallization system. At the earliest nucleation stages, the CC method allows the capture of prenucleation clusters and intermediate nanoclusers, spherical nanoparticles, and nanochains prior to enamel-like nanorod microstructure formations at later maturation stages. Amel-ACP nanoscaled building blocks are formed spontaneously by synergistic interactions between flexible Amel protein molecules and Ca-P prenucleation clusters, and these spherical nanoparticles evolve by orientated aggregation to form nanochains. Our results suggest that, in vivo, Amel may determine the structure of enamel by controlling prenucleation cluster aggregation at the earliest stages by forming stable Amel-ACP microstructures prior to subsequent crystal growth and mineral maturation.
Collapse
Affiliation(s)
- Xiudong Yang
- Department of Chemistry, The State University of New York at Buffalo, Amherst, New York 14260
| | - Lijun Wang
- College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Yueling Qin
- Department of Physics, The State University of New York at Buffalo, Amherst, New York 14260
| | - Zhi Sun
- Center for Craniofacial Molecular Biology, School of Dentistry, University of Southern California, Los Angeles, California 90033
| | - Zachary J. Henneman
- Department of Chemistry, The State University of New York at Buffalo, Amherst, New York 14260
| | - Janet Moradian-Oldak
- Center for Craniofacial Molecular Biology, School of Dentistry, University of Southern California, Los Angeles, California 90033
| | - George H. Nancollas
- Department of Chemistry, The State University of New York at Buffalo, Amherst, New York 14260
| |
Collapse
|
9
|
He X, Li W, Habelitz S. The cooperative self-assembly of 25 and 23kDa amelogenins. J Struct Biol 2008; 164:314-21. [PMID: 18845261 DOI: 10.1016/j.jsb.2008.09.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2008] [Revised: 09/12/2008] [Accepted: 09/15/2008] [Indexed: 11/29/2022]
Abstract
Self-assembly of the extracellular matrix protein amelogenin is believed to play an essential role in regulating the growth and organization of enamel crystals during enamel formation. The full-length amelogenin uniquely regulates the growth, shape, and arrangement of enamel crystals. Protein hydrolysis will ultimately facilitate a tissue with high mineral content. Protein processing is however highly specific suggesting a functional role of the cleaved amelogenins in enamel maturation. Here we hypothesize that the cooperative self-assembly of the recombinant full-length amelogenin 25kDa and the 23kDa proteolytic cleavage product is a function of pH, mixing ratio and incubation time and is associated with the isoelectric point of the protein. Self-assembly of amelogenin into nanospheres which increased in size with increasing pH was observed by atomic force microscopy. Elongated structures of about 100nm length and 25nm width formed over several days for amelogenin 25 and 23kDa predominantly at pH-values of 6.5 and 7.5, respectively. When both proteins 25 and 23kDa were mixed, self-assembled nanostrings of 200-300nm length consisting of fused nanospheres were obtained at pH around 7.0 within 24h. The protein nanostrings formed links over time and a continuous mesh was obtained after 7 days. Electrical conductivity data also showed gradual changes when both amelogenins were mixed in solutions supporting the idea that elongated structures form over extended periods of time. We propose that due to the difference in the isoelectric point, self-assembled nanospheres composed of 23 or 25kDa amelogenin have opposite ionic charges at pH-values around 7.0 and thus experience ionic attraction that enables cooperative self-assembly.
Collapse
Affiliation(s)
- Xiaodong He
- Department of Preventive and Restorative Dental Sciences, 707 Parnassus Ave., University of California, San Francisco, CA 94143-0758, USA
| | | | | |
Collapse
|
10
|
Zhou B, Liu Y, Wei W, Mao J. GEPIs-HA hybrid: a novel biomaterial for tooth repair. Med Hypotheses 2008; 71:591-3. [PMID: 18657914 DOI: 10.1016/j.mehy.2008.04.024] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2008] [Revised: 04/07/2008] [Accepted: 04/15/2008] [Indexed: 10/21/2022]
Abstract
Dental caries are slowly progressive and infectious disease, which result in localized dissolution and destruction of the calcified tissues. In routine clinical treatments, microleakage following with secondary caries usually occurs due to the discrepancy in physico-chemical property between filled materials and tooth. Ideal filling materials for tooth defect should be similar to the structure and chemical composition of natural tooth. Recently, molecular biomimetics developed a novel nanotechnology through biology, which fabricate materials based on molecular recognition between genetically engineered peptides for inorganics (GEPIs) and inorganic crystal. Since GEPIs can be used in the assembly of functional nanostructures, we hypothesis that an analogue of dental hard tissue, hybrid of GEPIs and HA crystal, might be engineered using the recognition properties between GEPIs and HA crystal.
Collapse
Affiliation(s)
- Bin Zhou
- Department of Stomatology, Tongji Hospital, Huazhong University of Science and Technology, No. 1095, Jiefang Road, Hankou, Wuhan, Hubei 430030, China.
| | | | | | | |
Collapse
|
11
|
Gergely C, Szalontai B, Moradian-Oldak J, Cuisinier FJG. Polyelectrolyte-mediated adsorption of amelogenin monomers and nanospheres forming mono- or multilayers. Biomacromolecules 2007; 8:2228-36. [PMID: 17579474 PMCID: PMC2586669 DOI: 10.1021/bm070088+] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have applied optical waveguide lightmode spectroscopy combined with streaming potential measurements and Fourier-transformed infrared spectroscopy to investigate adsorption of amelogenin nanospheres onto polyelectrolytes. The long-term objective was to better understand the chemical nature of these assemblies and to gain further insight into the molecular mechanisms involved during self-assembly. It was found that monolayers of monomers and negatively charged nanospheres of a recombinant amelogenin (rM179) irreversibly adsorbed onto a positively charged polyelectrolyte multilayer films. On the basis of measurements performed at different temperatures, it was demonstrated that intermolecular interactions for the formation of nanospheres were not affected by their adsorption onto polyelectrolytes. Consecutive adsorption of nanospheres resulting in the formation of multilayer structures was possible by using cationic poly(l-lysine) as mediators. N-Acetyl-d-glucosamine (GlcNac) did not disturb the nanosphere-assembled protein's structure, and it only affected the adsorption of monomeric amelogenin. Infrared spectroscopy of adsorbed amelogenin revealed conformational differences between the monomeric and assembled forms of rM179. While there was a considerable amount of alpha-helices in the monomers, beta-turn and beta-sheet structures dominated the assembled proteins. Our work constitutes the first report on a structurally controlled in vitro buildup of an rM179 nanosphere monolayer-based matrix. Our data support the notion that amelogenin self-assembly is mostly driven by hydrophobic interactions and that amelogenin/PEM interactions are dominated by electrostatic forces. We suggest that similar forces can govern amelogenin interactions with non-amelogenins or the mineral phase during enamel biomineralization.
Collapse
Affiliation(s)
- Csilla Gergely
- Groupe d'étude des Semi-Conducteurs, Université Montpellier II, Montpellier Cedex 5, France.
| | | | | | | |
Collapse
|