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Zhang J, Bai Y, Wang J, Li B, Habelitz S, Lu JX. Calcium interactions in amelogenin-derived peptide assembly. Front Physiol 2022; 13:1063970. [PMID: 36589425 PMCID: PMC9795176 DOI: 10.3389/fphys.2022.1063970] [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: 10/07/2022] [Accepted: 12/02/2022] [Indexed: 12/15/2022] Open
Abstract
Phosphorylation of serine residues has been recognized as a pivotal event in the evolution of mineralized tissues in many biological systems. During enamel development, the extracellular matrix protein amelogenin is most abundant and appears to be critical to the extreme high aspect ratios (length:width) of apatite mineral fibers reaching several millimeters in larger mammalian teeth. A 14-residue peptide (14P2, residues Gly8 to Thr21) was previously identified as a key sequence mediating amelogenin assembly formation, the domain also contains the native single phosphoserine residue (Ser16) of the full-length amelogenin. In this research, 14P2 and its phosphorylated form (p14P2) were investigated at pH 6.0 with various calcium and phosphate ion concentrations, indicating that both peptides could self-assemble into amyloid-like conformation but with differences in structural details. With calcium, the distance between 31P within the p14P2 self-assemblies is averaged to be 4.4 ± 0.2Å, determined by solid-state NMR 31P PITHIRDS-CT experiments. Combining with other experimental results, solid-state Nuclear Magnetic Resonance (SSNMR) suggests that the p14P2 self-assemblies are in parallel in-register β-sheet conformation and divalent calcium ions most likely connect two adjacent peptide chains by binding to the phosphate group of Ser16 and the carboxylate of Glu18 side-chain. This study on the interactions between calcium ions and amelogenin-derived peptides provides insights on how amelogenin may self-assemble in the presence of calcium ions in early enamel development.
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Affiliation(s)
- Jing Zhang
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China,University of Chinese Academy of Sciences, Beijing, China,State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, China
| | - Yushi Bai
- Department of Preventative and Restorative Dental Sciences, School of Dentistry, University of California, San Francisco, San Francisco, CA, United States
| | - Jian Wang
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Bing Li
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Stefan Habelitz
- Department of Preventative and Restorative Dental Sciences, School of Dentistry, University of California, San Francisco, San Francisco, CA, United States,*Correspondence: Jun-xia Lu, ; Stefan Habelitz,
| | - Jun-xia Lu
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China,*Correspondence: Jun-xia Lu, ; Stefan Habelitz,
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Amelogenin-Derived Peptides in Bone Regeneration: A Systematic Review. Int J Mol Sci 2021; 22:ijms22179224. [PMID: 34502132 PMCID: PMC8431254 DOI: 10.3390/ijms22179224] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 08/03/2021] [Accepted: 08/11/2021] [Indexed: 11/17/2022] Open
Abstract
Amelogenins are enamel matrix proteins currently used to treat bone defects in periodontal surgery. Recent studies have highlighted the relevance of amelogenin-derived peptides, named LRAP, TRAP, SP, and C11, in bone tissue engineering. Interestingly, these peptides seem to maintain or even improve the biological activity of the full-length protein, which has received attention in the field of bone regeneration. In this article, the authors combined a systematic and a narrative review. The former is focused on the existing scientific evidence on LRAP, TRAP, SP, and C11's ability to induce the production of mineralized extracellular matrix, while the latter is concentrated on the structure and function of amelogenin and amelogenin-derived peptides. Overall, the collected data suggest that LRAP and SP are able to induce stromal stem cell differentiation towards osteoblastic phenotypes; specifically, SP seems to be more reliable in bone regenerative approaches due to its osteoinduction and the absence of immunogenicity. However, even if some evidence is convincing, the limited number of studies and the scarcity of in vivo studies force us to wait for further investigations before drawing a solid final statement on the real potential of amelogenin-derived peptides in bone tissue engineering.
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Zhang J, Wang J, Ma C, Lu J. Hydroxyapatite Formation Coexists with Amyloid-like Self-Assembly of Human Amelogenin. Int J Mol Sci 2020; 21:E2946. [PMID: 32331340 PMCID: PMC7216246 DOI: 10.3390/ijms21082946] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 03/28/2020] [Accepted: 04/07/2020] [Indexed: 12/19/2022] Open
Abstract
Tooth enamel is formed in an extracellular environment. Amelogenin, the major component in the protein matrix of tooth enamel during the developing stage, could assemble into high molecular weight structures, regulating enamel formation. However, the molecular structure of amelogenin protein assembly at the functional state is still elusive. In this work, we found that amelogenin is able to induce calcium phosphate minerals into hydroxyapatite (HAP) structure in vitro at pH 6.0. Assessed using X-ray diffraction (XRD) and 31P solid-state NMR (SSNMR) evidence, the formed HAP mimics natural enamel closely. The structure of amelogenin protein assembly coexisting with the HAP was also studied using atomic force microscopy (AFM), transmission electron microscopy (TEM) and XRD, indicating the β-amyloid structure of the protein. SSNMR was proven to be an important tool in detecting both the rigid and dynamic components of the protein assembly in the sample, and the core sequence 18EVLTPLKWYQSI29 was identified as the major segment contributing to the β-sheet secondary structure. Our research suggests an amyloid structure may be an important factor in controlling HAP formation at the right pH conditions with the help of other structural components in the protein assembly.
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Affiliation(s)
- Jing Zhang
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China; (J.Z.); (J.W.); (C.M.)
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jian Wang
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China; (J.Z.); (J.W.); (C.M.)
| | - Chengwei Ma
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China; (J.Z.); (J.W.); (C.M.)
| | - Junxia Lu
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China; (J.Z.); (J.W.); (C.M.)
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Zhuo XF, Wang J, Zhang J, Jiang LL, Hu HY, Lu JX. Solid-State NMR Reveals the Structural Transformation of the TDP-43 Amyloidogenic Region upon Fibrillation. J Am Chem Soc 2020; 142:3412-3421. [PMID: 32003979 DOI: 10.1021/jacs.9b10736] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
TDP-43 is a primary pathological hallmark protein of amyotrophic lateral sclerosis and frontotemporal lobar degeneration, which may exist in the form of amyloid inclusions in the cells of patients. In addition to serving as a biomarker for these diseases, TDP-43 can also directly trigger neurodegeneration. We previously determined the amyloidogenic core region of TDP-43 (residues 311-360) and showed by solution NMR that this region includes two α-helices [(321-330) and (335-343)] in solution. We suggested that the helix-to-sheet structural transformation initiates TDP-43 aggregation. In the present study, X-ray diffraction shows that TDP-43 (311-360) aggregates adopt a cross-β structure. Thioredoxin (Trx)-fused TDP-43 (311-360) can undergo liquid-liquid phase separation (LLPS) before fibrillation, suggesting that phase separation is an intermediate step before amyloid formation. Solid-state NMR (SSNMR), carried out to elucidate the structural changes of TDP-43 (311-360) at the atomic level, indicates five β-strands of the amyloids formed, with the major two β-strands contributed by the first helical region in the solution structure. The NMR evidence is also in support of the fibril having a parallel in-register conformation, implying a mechanism in which the helix-helix interactions in LLPS are converted into β-strand parallel lateral association upon fibrillation. Our studies have assigned many key interresidue interactions that contribute to the stability of the fibril, including F316 with I318 and Q327 and W334 with A325, A326, A329, and S332. SSNMR with 1H detection reveals a unique close interaction between the indole Nε1-Hε1 of W334 and the side-chain carbonyl of Q343. This interaction could be a very important factor in initiating TDP-43 (311-360) folding/misfolding in LLPS.
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Affiliation(s)
- Xiao-Feng Zhuo
- School of Life Science and Technology , ShanghaiTech University , Shanghai 201210 , People's Republic of China.,State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science , Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences , Shanghai 200031 , People's Republic of China.,University of Chinese Academy of Sciences , Beijing 100049 , People's Republic of China
| | - Jian Wang
- School of Life Science and Technology , ShanghaiTech University , Shanghai 201210 , People's Republic of China
| | - Jing Zhang
- School of Life Science and Technology , ShanghaiTech University , Shanghai 201210 , People's Republic of China.,State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science , Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences , Shanghai 200031 , People's Republic of China.,University of Chinese Academy of Sciences , Beijing 100049 , People's Republic of China
| | - Lei-Lei Jiang
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science , Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences , Shanghai 200031 , People's Republic of China
| | - Hong-Yu Hu
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science , Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences , Shanghai 200031 , People's Republic of China
| | - Jun-Xia Lu
- School of Life Science and Technology , ShanghaiTech University , Shanghai 201210 , People's Republic of China
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