http://hdl.handle.net/10027/7697 Thu, 23 May 2013 09:39:13 GMT 2013-05-23T09:39:13Z http://hdl.handle.net/10027/8216 Amelogenin Supramolecular Assembly in Nanospheres Defined by a Complex Helix-Coil-PPII Helix 3D-Structure Zhang, Xu; Ramirez, Benjamin E.; Liao, Xiubei; Diekwisch, Thomas G. H. Tooth enamel, the hardest material in the human body, is formed within a self-assembled matrix consisting mostly of amelogenin proteins. Here we have determined the complete mouse amelogenin structure under physiological conditions and defined interactions between individual domains. NMR spectroscopy revealed four major amelogenin structural motifs, including an N-terminal assembly of four a-helical segments (S9-V19, T21-P33, Y39-W45, V53-Q56), an elongated random coil region interrupted by two 310 helices (,P60-Q117), an extended proline-rich PPII-helical region (P118-L165), and a charged hydrophilic C-terminus (L165-D180). HSQC experiments demonstrated ipsilateral interactions between terminal domains of individual amelogenin molecules, i.e. N-terminal interactions with corresponding N-termini and C-terminal interactions with corresponding C-termini, while the central random coil domain did not engage in interactions. Our HSQC spectra of the full-length amelogenin central domain region completely overlapped with spectra of the monomeric Amel-M fragment, suggesting that the central amelogenin coil region did not involve in assembly, even in assembled nanospheres. This finding was confirmed by analytical ultracentrifugation experiments. We conclude that under conditions resembling those found in the developing enamel protein matrix, amelogenin molecules form complex 3D-structures with N-terminal a-helix-like segments and C-terminal PPII-helices, which self-assemble through ipsilateral interactions at the N-terminus of the molecule. Copyright © 2011 Zhang et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. DOI:10.1371/journal.pone.0024952 Sat, 01 Oct 2011 05:00:00 GMT http://hdl.handle.net/10027/8216 2011-10-01T05:00:00Z http://hdl.handle.net/10027/7738 Apatite Microtopographies Instruct Signaling Tapestries for Progenitor-Driven New Attachment of Teeth Dangaria, Smit J.; Ito, Yoshihiro; Yin, LeiLei; Valdre, Giovanni; Luan, Xianghong; Diekwisch, Thomas G.H. Dimension and structure of extracellular matrix surfaces have powerful influences on cell shape, adhesion, and gene expression. Here we show that natural tooth root topographies induce integrin-mediated extracellular matrix signaling cascades in tandem with cell elongation and polarization to generate physiological periodontium-like tissues. In this study we replanted surface topography instructed periodontal progenitors into rat alveolar bone sockets for 8 and 16 weeks, resulting in complete reattachment of tooth roots to the surrounding alveolar bone with a periodontal fiber apparatus closely matching physiological controls along the entire root surface. Displacement studies and biochemical analyses confirmed that progenitor-based engineered periodontal tissues were similar to control teeth and uniquely derived from preimplantation green fluorescent protein (GFP)-labeled progenitors. Together, these studies illustrate the capacity of natural extracellular surface topographies to instruct progenitor cell populations to fully regenerate complex cellular and structural morphologies of tissues once lost to disease. We suggest that our strategy could be used for the replantation of teeth lost due to trauma or as a novel approach for tooth replacement using tooth-shaped replicas. This is a copy of an article published in Tissue Engineering Part A © 2011 Copyright Mary Ann Liebert, Inc.; Tissue Engineering Part A is available online at: http://www.liebertonline.com. (DOI: 10.1089/ten.tea.2010.0264) Tue, 01 Feb 2011 06:00:00 GMT http://hdl.handle.net/10027/7738 2011-02-01T06:00:00Z