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Yuan X, Liu B, Cuevas P, Brunski J, Aellos F, Petersen J, Koehne T, Bröer S, Grüber R, LeBlanc A, Zhang X, Xu Q, Helms J. Linking the Mechanics of Chewing to Biology of the Junctional Epithelium. J Dent Res 2023; 102:1252-1260. [PMID: 37555395 PMCID: PMC10626588 DOI: 10.1177/00220345231185288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/10/2023] Open
Abstract
The capacity of a tissue to continuously alter its phenotype lies at the heart of how an animal is able to quickly adapt to changes in environmental stimuli. Within tissues, differentiated cells are rigid and play a limited role in adapting to new environments; however, differentiated cells are replenished by stem cells that are defined by their phenotypic plasticity. Here we demonstrate that a Wnt-responsive stem cell niche in the junctional epithelium is responsible for the capability of this tissue to quickly adapt to changes in the physical consistency of a diet. Mechanical input from chewing is required to both establish and maintain this niche. Since the junctional epithelium directly attaches to the tooth surface via hemidesmosomes, a soft diet requires minimal mastication, and consequently, lower distortional strains are produced in the tissue. This reduced strain state is accompanied by reduced mitotic activity in both stem cells and their progeny, leading to tissue atrophy. The atrophied junctional epithelium exhibits suboptimal barrier functions, allowing the ingression of bacteria into the underlying connective tissues, which in turn trigger inflammation and mild alveolar bone loss. These data link the mechanics of chewing to the biology of tooth-supporting tissues, revealing how a stem cell niche is responsible for the remarkable adaptability of the junctional epithelium to different diets.
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Affiliation(s)
- X. Yuan
- Department of Surgery, Stanford University School of Medicine, Stanford, CA, USA
- Department of Otolaryngology-Head & Neck Surgery, School of Medicine, Indiana University, Indianapolis, IN, USA
| | - B. Liu
- Department of Surgery, Stanford University School of Medicine, Stanford, CA, USA
| | - P. Cuevas
- Department of Surgery, Stanford University School of Medicine, Stanford, CA, USA
| | - J. Brunski
- Department of Surgery, Stanford University School of Medicine, Stanford, CA, USA
| | - F. Aellos
- Department of Surgery, Stanford University School of Medicine, Stanford, CA, USA
| | - J. Petersen
- Department of Orthodontics, University of Leipzig Medical Center, Saxony, Germany
| | - T. Koehne
- Department of Orthodontics, University of Leipzig Medical Center, Saxony, Germany
| | - S. Bröer
- Institute of Pharmacology and Toxicology, School of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - R. Grüber
- Department of Oral Biology, University Clinic of Dentistry, Medical University of Vienna, Vienna, Austria
| | - A. LeBlanc
- Centre for Oral, Clinical & Translational Sciences, Faculty of Dentistry, Oral & Craniofacial Sciences, King’s College London, London, UK
| | - X. Zhang
- Department of Surgery, Stanford University School of Medicine, Stanford, CA, USA
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Disease, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Q. Xu
- Department of Surgery, Stanford University School of Medicine, Stanford, CA, USA
- The Affiliated Hospital of Qingdao University, College of Stomatology, Qingdao University, Qingdao, China
| | - J.A. Helms
- Department of Surgery, Stanford University School of Medicine, Stanford, CA, USA
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Grüber R, Aranda J, Bellili A, Tuñón I, Dumont E. Free energy profiles for two ubiquitous damaging agents: methylation and hydroxylation of guanine in B-DNA. Phys Chem Chem Phys 2017; 19:14695-14701. [PMID: 28537602 DOI: 10.1039/c6cp07966k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
DNA methylation and hydroxylation are two ubiquitous reactions in DNA damage induction, yet insights are scarce concerning the free energy of activation within B-DNA. We resort to multiscale simulations to investigate the attack of a hydroxyl radical and of the primary diazonium onto a guanine embedded in a solvated dodecamer. Reaction free energy profiles characterize two strongly exergonic processes, yet allow unprecedented quantification of the barrier towards this damage reaction, not higher than 6 kcal mol-1 and sometimes inexistent, and of the exergonicities. In the case of the [G(C8)-OH]˙ intermediate, we challenge the functional dependence of such simulations: recently-proposed functionals, such as M06-2X and LC-BLYP, agree on a ∼4 kcal mol-1 barrier, whereas the hybrid GGA B3LYP functional predicts a barrier-less pathway. In the long term, multiscale approaches can help build up a unified panorama of DNA lesion induction. These results stress the importance of DFT/MM-MD simulations involving new functionals towards the sound modelling of biomolecule damage even in the ground state.
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Affiliation(s)
- R Grüber
- Univ. Lyon, Ens de Lyon, CNRS UMR 5182, Université Claude Bernard Lyon 1, Laboratoire de Chimie, F-69342 Lyon, France.
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