1
|
Ahmadi A, Duval VF, Bartlett JD, Hofer IS, Mafi J, Villaflores CWA, Sarkisian CA. Examining patient perspectives on low-value care: Findings from a survey on preoperative testing for cataract surgery. J Am Geriatr Soc 2023; 71:3641-3644. [PMID: 37436065 PMCID: PMC11006278 DOI: 10.1111/jgs.18494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 06/09/2023] [Accepted: 06/13/2023] [Indexed: 07/13/2023]
Affiliation(s)
- Alast Ahmadi
- Department of Internal Medicine, University of California Irvine, Irvine, California, United States
| | - Victor F. Duval
- Department of Anesthesiology, David Geffen School of Medicine at UCLA, Los Angeles, California, United States
| | - John D. Bartlett
- Department of Ophthalmology, University of California Los Angeles David Geffen School of Medicine, Los Angeles, California, USA
| | - Ira S. Hofer
- Department of Anesthesiology, Icahn School of Medicine at Mount Sinai, New York, United States
| | - John Mafi
- Division of General Internal Medicine and Health Services Research, Department of Medicine at the David Geffen School of Medicine at UCLA, Los Angeles, California, United States
| | - Chad Wes A. Villaflores
- Division of General Internal Medicine and Health Services Research, Department of Medicine at the David Geffen School of Medicine at UCLA, Los Angeles, California, United States
| | - Catherine A. Sarkisian
- Division of General Internal Medicine and Health Services Research, Department of Medicine at the David Geffen School of Medicine at UCLA, Los Angeles, California, United States
- VA Greater Los Angeles Geriatric Research Education and Clinical Center, Los Angeles, California, United States
| |
Collapse
|
2
|
Shin M, Matsushima A, Nagao JI, Tanaka Y, Harada H, Okabe K, Bartlett JD. Mobility gene expression differences among wild-type, Mmp20 null and Mmp20 over-expresser mice plus visualization of 3D mouse ameloblast directional movement. Sci Rep 2023; 13:18829. [PMID: 37914726 PMCID: PMC10620228 DOI: 10.1038/s41598-023-44627-0] [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] [Received: 05/23/2023] [Accepted: 10/10/2023] [Indexed: 11/03/2023] Open
Abstract
Enamel forming ameloblasts move away from the dentino-enamel junction and also move relative to each other to establish enamel shape during the secretory stage of enamel development. Matrix metalloproteinase-20 (MMP20) is a tooth specific proteinase essential for proper enamel formation. We previously reported that MMP20 cleaves cadherins and may regulate ameloblast movement. Here, we used an Amelx promoter driven tdTomato reporter to label mouse ameloblasts. With these transgenic mice, we assessed ameloblast mobility group dynamics and gene expression. Three-dimensional imaging of mouse ameloblasts were observed in hemi-mandibles by using a tissue clearing technique. The three-dimensional ameloblast layer in Tg(Amelx-Mmp20) mice that overexpress MMP20 was uneven and the ameloblasts migrated away from this layer. Mouse ameloblast movement toward incisal tips was monitored by ex vivo time-lapse imaging. Gene expression related to cell migration and adhesion was analyzed in ameloblasts from wild-type mice, Mmp20-/- mice with no functional MMP20 and from Tg(Amelx-Mmp20) overexpressing mice. Gene expression was altered in Mmp20-/- and Tg(Amelx-Mmp20) mice compared to wild type. Among the genes assessed, those encoding laminins and a gap junction protein were upregulated in Mmp20-/- mice. New techniques and findings described in this study may lead to an improved understanding of ameloblast movement during enamel formation.
Collapse
Affiliation(s)
- Masashi Shin
- Section of Cellular Physiology, Department of Physiological Science and Molecular Biology, Fukuoka Dental College, 2-15-1 Tamura, Sawara-ku, Fukuoka, 814-0193, Japan.
- Oral Medicine Research Center, Fukuoka Dental College, Fukuoka, Japan.
| | - Aya Matsushima
- Section of Cellular Physiology, Department of Physiological Science and Molecular Biology, Fukuoka Dental College, 2-15-1 Tamura, Sawara-ku, Fukuoka, 814-0193, Japan
| | - Jun-Ichi Nagao
- Oral Medicine Research Center, Fukuoka Dental College, Fukuoka, Japan
- Section of Infection Biology, Department of Functional Bioscience, Fukuoka Dental College, Fukuoka, Japan
| | - Yoshihiko Tanaka
- Oral Medicine Research Center, Fukuoka Dental College, Fukuoka, Japan
- Section of Infection Biology, Department of Functional Bioscience, Fukuoka Dental College, Fukuoka, Japan
| | - Hidemitsu Harada
- Divison of Developmental Biology and Regenerative Medicine, Department of Anatomy, Iwate Medical University, Iwate, Japan
| | - Koji Okabe
- Section of Cellular Physiology, Department of Physiological Science and Molecular Biology, Fukuoka Dental College, 2-15-1 Tamura, Sawara-ku, Fukuoka, 814-0193, Japan
| | - John D Bartlett
- Division of Biosciences, College of Dentistry, Ohio State University, Columbus, OH, USA
| |
Collapse
|
3
|
Hsu YH, Hassan A, Trout A, Bartlett JD, Smith CE, Simmer JP, McComb DW. The Characterization of Hydroxyapatite and Octa-calcium Phosphate with Electron Energy Loss Spectroscopy. Microsc Microanal 2023; 29:1223-1225. [PMID: 37613591 DOI: 10.1093/micmic/ozad067.629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Affiliation(s)
- Ya-Hsiang Hsu
- Department of Materials Science and Engineering, The Ohio State University, Columbus, OH, USA
| | - Asra Hassan
- Center for Electron Microscopy and Analysis, The Ohio State University, Columbus, OH, USA
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson AFB, OH, USA
| | - Amanda Trout
- Center for Electron Microscopy and Analysis, The Ohio State University, Columbus, OH, USA
| | - John D Bartlett
- Division of Biosciences, Ohio State University College of Dentistry, Columbus, OH, USA
| | - Charles E Smith
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, MI, USA
- Department of Anatomy and Cell Biology, Faculty of Medicine and Health Sciences, McGill University, Montreal, QC, Canada
| | - James P Simmer
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, MI, USA
| | - David W McComb
- Department of Materials Science and Engineering, The Ohio State University, Columbus, OH, USA
- Center for Electron Microscopy and Analysis, The Ohio State University, Columbus, OH, USA
| |
Collapse
|
4
|
Shin M, Matsushima A, Kajiya H, Okamoto F, Ogata K, Oka K, Ohshima H, Bartlett JD, Okabe K. Conditional knockout of transient receptor potential melastatin 7 in the enamel epithelium: Effects on enamel formation. Eur J Oral Sci 2023; 131:e12920. [PMID: 36794562 DOI: 10.1111/eos.12920] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 01/21/2023] [Indexed: 02/17/2023]
Abstract
Transient receptor potential melastatin 7 (TRPM7) is a unique ion channel connected to a kinase domain. We previously demonstrated that Trpm7 expression is high in mouse ameloblasts and odontoblasts, and that amelogenesis is impaired in TRPM7 kinase-dead mice. Here, we analyzed TRPM7 function during amelogenesis in Keratin 14-Cre;Trpm7fl/fl conditional knockout (cKO) mice and Trpm7 knockdown cell lines. cKO mice showed lesser tooth pigmentation than control mice and broken incisor tips. Enamel calcification and microhardness were lower in cKO mice. Electron probe microanalysis (EPMA) showed that the calcium and phosphorus contents in the enamel were lower in cKO mouse than in control mice. The ameloblast layer in cKO mice showed ameloblast dysplasia at the maturation stage. The morphological defects were observed in rat SF2 cells with Trpm7 knockdown. Compared with mock transfectants, the Trpm7 knockdown cell lines showed lower levels of calcification with Alizarin Red-positive staining and an impaired intercellular adhesion structures. These findings suggest that TRPM7 is a critical ion channel in enamel calcification for the effective morphogenesis of ameloblasts during amelogenesis.
Collapse
Affiliation(s)
- Masashi Shin
- Section of Cellular Physiology, Department of Physiological Science and Molecular Biology, Fukuoka Dental College, Fukuoka, Japan
- Oral Medicine Research Center, Fukuoka Dental College, Fukuoka, Japan
| | - Aya Matsushima
- Section of Cellular Physiology, Department of Physiological Science and Molecular Biology, Fukuoka Dental College, Fukuoka, Japan
| | - Hiroshi Kajiya
- Section of Cellular Physiology, Department of Physiological Science and Molecular Biology, Fukuoka Dental College, Fukuoka, Japan
- Oral Medicine Research Center, Fukuoka Dental College, Fukuoka, Japan
| | - Fujio Okamoto
- Section of Cellular Physiology, Department of Physiological Science and Molecular Biology, Fukuoka Dental College, Fukuoka, Japan
| | - Kayoko Ogata
- Oral Medicine Research Center, Fukuoka Dental College, Fukuoka, Japan
- Section of Functional Structure, Department of Morphological Biology, Fukuoka Dental College, Fukuoka, Japan
| | - Kyoko Oka
- Oral Medicine Research Center, Fukuoka Dental College, Fukuoka, Japan
- Section of Pediatric Dentistry, Department of Oral Growth and development, Fukuoka Dental College, Fukuoka, Japan
| | - Hayato Ohshima
- Division of Anatomy and Cell Biology of the Hard Tissue, Department of Tissue Regeneration and Reconstruction, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - John D Bartlett
- Division of Biosciences, Ohio State University, College of Dentistry, Columbus, Ohio, USA
| | - Koji Okabe
- Section of Cellular Physiology, Department of Physiological Science and Molecular Biology, Fukuoka Dental College, Fukuoka, Japan
| |
Collapse
|
5
|
Shin M, Mori S, Mizoguchi T, Arai A, Kajiya H, Okamoto F, Bartlett JD, Matsushita M, Udagawa N, Okabe K. Mesenchymal cell TRPM7 expression is required for bone formation via the regulation of chondrogenesis. Bone 2023; 166:116579. [PMID: 36210025 DOI: 10.1016/j.bone.2022.116579] [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] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 09/20/2022] [Accepted: 10/03/2022] [Indexed: 11/07/2022]
Abstract
Transient receptor potential melastatin-subfamily member 7 (TRPM7) is a bifunctional protein containing a kinase fused to an ion channel permeated with cations, including Ca2+ and Mg2+. Trpm7-null mice show embryonic lethality. Paired related homeobox 1 (Prx1) is expressed in undifferentiated mesenchymal cells such as the progenitor cells of both chondrocytes and osteoblasts involved in limb skeleton formation. Prx1-Cre-dependent Trpm7 mesenchymal-deleted mice were generated to examine the role of TRPM7 in bone development. We found that Prx1-Cre;Trpm7fl/fl mice had shortened bones and impaired trabecular bone formation. Trabecular bone parameters, such as the bone volume (BV/TV), and trabecular number (Tb.N), were decreased in Prx1-Cre;Trpm7fl/fl mice. The cortical bone parameters of cortical bone area (Ct.Ar) and cortical bone thickness (Ct.Th) were also down-regulated in these mice. The bone formation rate in Prx1-Cre;Trpm7fl/fl mice was unchanged, but the hypertrophic area and cell size of the zone were smaller, and the expression of Col2a1, Col10a1 and Mmp13 was downregulated compared with control mice. These findings suggest impaired chondrogenesis in Prx1-Cre;Trpm7fl/fl mice compared to control mice. The receptor activator of nuclear factor-kappa B ligand (RANKL) expression was increased, and RANKL-positive cells and osteoclasts were markedly accumulated in the boundary region between the growth plate and trabecular bone. In contrast, TRPM7 KR mice, which are kinase-dead mutants in which the TRPM7 ion channel function has not been altered, showed no marked differences in trabecular or cortical bone parameters compared to wild-type mice. These findings suggest that TRPM7 is critical as a cation channel rather than as a kinase in bone development via the regulation of chondrogenesis.
Collapse
Affiliation(s)
- Masashi Shin
- Section of Cellular Physiology, Department of Physiological Science and Molecular Biology, Fukuoka Dental College, Fukuoka, Japan; Oral Medicine Research Center, Fukuoka Dental College, Fukuoka, Japan
| | - Shihomi Mori
- Section of Oral Surgery, Department of Oral and Maxillofacial Surgery, Fukuoka Dental College, Fukuoka, Japan
| | | | - Atsushi Arai
- Department of Orthodontics, Matsumoto Dental University, Nagano, Japan
| | - Hiroshi Kajiya
- Section of Cellular Physiology, Department of Physiological Science and Molecular Biology, Fukuoka Dental College, Fukuoka, Japan; Oral Medicine Research Center, Fukuoka Dental College, Fukuoka, Japan
| | - Fujio Okamoto
- Section of Cellular Physiology, Department of Physiological Science and Molecular Biology, Fukuoka Dental College, Fukuoka, Japan
| | - John D Bartlett
- Division of Biosciences, Ohio State University, College of Dentistry, Columbus, OH, USA
| | - Masayuki Matsushita
- Department of Molecular and Cellular Physiology, University of the Ryukyus, Okinawa, Japan
| | - Nobuyuki Udagawa
- Department of Biochemistry, Matsumoto Dental University, Nagano, Japan
| | - Koji Okabe
- Section of Cellular Physiology, Department of Physiological Science and Molecular Biology, Fukuoka Dental College, Fukuoka, Japan.
| |
Collapse
|
6
|
Shahid S, Ikeda A, Layana MC, Bartlett JD. ADAM10: Possible functions in enamel development. Front Physiol 2022; 13:1032383. [PMID: 36505044 PMCID: PMC9732274 DOI: 10.3389/fphys.2022.1032383] [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] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 11/14/2022] [Indexed: 11/27/2022] Open
Abstract
ADAM10 is A Disintegrin And Metalloproteinase (ADAM) family member that is membrane bound with its catalytic domain present on the cell surface. It is a sheddase that cleaves anchored cell surface proteins to shed them from the cell surface. ADAM10 can cleave at least a hundred different proteins and is expressed in most tissues of the body. ADAM10 is best characterized for its role in Notch signaling. Interestingly, ADAM10 is transported to specific sites on the cell surface by six different tetraspanins. Although the mechanism is not clear, tetraspanins can regulate ADAM10 substrate specificity, which likely contributes to the diversity of ADAM10 substrates. In developing mouse teeth, ADAM10 is expressed in the stem cell niche and subsequently in pre-ameloblasts and then secretory stage ameloblasts. However, once ameloblasts begin transitioning into the maturation stage, ADAM10 expression abruptly ceases. This is exactly when ameloblasts stop their movement that extends enamel crystallites and when the enamel layer reaches its full thickness. ADAM10 may play an important role in enamel development. ADAM10 can cleave cadherins and other cell-cell junctions at specific sites where the tetraspanins have transported it and this may promote cell movement. ADAM10 can also cleave the transmembrane proteins COL17A1 and RELT. When either COL17A1 or RELT are mutated, malformed enamel may occur in humans and mice. So, ADAM10 may also regulate these proteins that are necessary for proper enamel development. This mini review will highlight ADAM10 function, how that function is regulated by tetraspanins, and how ADAM10 may promote enamel formation.
Collapse
|
7
|
Simmer JP, Hu JCC, Hu Y, Zhang S, Liang T, Wang SK, Kim JW, Yamakoshi Y, Chun YH, Bartlett JD, Smith CE. A genetic model for the secretory stage of dental enamel formation. J Struct Biol 2021; 213:107805. [PMID: 34715329 PMCID: PMC8665125 DOI: 10.1016/j.jsb.2021.107805] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [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] [Received: 08/25/2021] [Revised: 10/18/2021] [Accepted: 10/20/2021] [Indexed: 01/13/2023]
Abstract
The revolution in genetics has rapidly increased our knowledge of human and mouse genes that are critical for the formation of dental enamel and helps us understand how enamel evolved. In this graphical review we focus on the roles of 41 genes that are essential for the secretory stage of amelogenesis when characteristic enamel mineral ribbons initiate on dentin and elongate to expand the enamel layer to the future surface of the tooth. Based upon ultrastructural analyses of genetically modified mice, we propose a molecular model explaining how a cell attachment apparatus including collagen 17, α6ß4 and αvß6 integrins, laminin 332, and secreted enamel proteins could attach to individual enamel mineral ribbons and mold their cross-sectional dimensions as they simultaneously elongate and orient them in the direction of the retrograde movement of the ameloblast membrane.
Collapse
Affiliation(s)
- James P Simmer
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, 1011 North University, Ann Arbor, MI 48108, USA.
| | - Jan C-C Hu
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, 1011 North University, Ann Arbor, MI 48108, USA.
| | - Yuanyuan Hu
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, 1011 North University, Ann Arbor, MI 48108, USA.
| | - Shelly Zhang
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, 1011 North University, Ann Arbor, MI 48108, USA.
| | - Tian Liang
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, 1011 North University, Ann Arbor, MI 48108, USA.
| | - Shih-Kai Wang
- Department of Dentistry, National Taiwan University School of Dentistry, No. 1, Changde St., Zhongzheng Dist., Taipei City 100, Taiwan; Department of Pediatric Dentistry, National Taiwan University Children's Hospital, No. 8, Zhongshan S. Rd., Zhongzheng Dist., Taipei City 100, Taiwan.
| | - Jung-Wook Kim
- Department of Molecular Genetics, School of Dentistry & Dental Research Institute, Seoul National University, Seoul, Korea; Department of Pediatric Dentistry, School of Dentistry & Dental Research Institute, Seoul National University, Seoul, Korea.
| | - Yasuo Yamakoshi
- Department of Biochemistry and Molecular Biology, School of Dental Medicine, Tsurumi University, 2-1-3 Tsurumi, Tsurumi-ku, Yokohama 230-8501, Japan.
| | - Yong-Hee Chun
- Department of Periodontics, School of Dentistry, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
| | - John D Bartlett
- Division of Biosciences, Ohio State University College of Dentistry, Columbus, OH, USA.
| | - Charles E Smith
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, 1011 North University, Ann Arbor, MI 48108, USA; Department of Anatomy & Cell Biology, Faculty of Medicine & Health Sciences, McGill University, Montreal, Quebec H3A 0C7, Canada.
| |
Collapse
|
8
|
Ahmadi A, Sorensen A, Villaflores CWA, Mafi JN, Vangala SS, Hofer IS, Bartlett JD, Cheng EM, Duval VF, Damberg C, Elashoff D, Goldstein NJ, Ladapo JA, Moore JM, Pessegueiro AM, Shu SB, Skootsky SA, Turner A, Sarkisian CA. Protocol for pragmatic randomised trial: integrating electronic health record-based behavioural economic 'nudges' into the electronic health record to reduce preoperative testing for patients undergoing cataract surgery. BMJ Open 2021; 11:e049568. [PMID: 34732478 PMCID: PMC8572383 DOI: 10.1136/bmjopen-2021-049568] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
INTRODUCTION Robust randomised trial data have shown that routine preoperative (pre-op) testing for cataract surgery patients is inappropriate. While guidelines have discouraged testing since 2002, cataract pre-op testing rates have remained unchanged since the 1990s. Given the challenges of reducing low-value care despite strong consensus around the evidence, innovative approaches are needed to promote high-value care. This trial evaluates the impact of an interdisciplinary electronic health record (EHR) intervention that is informed by behavioural economic theory. METHODS AND ANALYSIS This pragmatic randomised trial is being conducted at UCLA Health between June 2021 and June 2022 with a 12-month follow-up period. We are randomising all UCLA Health physicians who perform pre-op visits during the study period to one of the three nudge arms or usual care. These three nudge alerts address (1) patient harm, (2) increased out-of-pocket costs for patients and (3) psychological harm to the patients related to pre-op testing. The nudges are triggered when a physician starts to order a pre-op test. We hypothesise that receipt of a nudge will be associated with reduced pre-op testing. The primary outcome will be the change in the percentage of patients undergoing pre-op testing at 12 months. Secondary outcomes will include the percentage of patients undergoing specific categories of pre-op tests (labs, EKGs, chest X-rays (CXRs)), the efficacy of each nudge, same-day surgery cancellations and cost savings. ETHICS AND DISSEMINATION The study protocol was approved by the institutional review board of the University of California, Los Angeles as well as a nominated Data Safety Monitoring Board. If successful, we will have created a tool that can be disseminated rapidly to EHR vendors across the nation to reduce inappropriate testing for the most common low-risk surgical procedures in the country. TRIAL REGISTRATION NUMBER ClinicalTrials.gov identifier: NCT04104256.
Collapse
Affiliation(s)
- Alast Ahmadi
- University of California Los Angeles David Geffen School of Medicine, Los Angeles, California, USA
- Internal Medicine, University of California Irvine School of Medicine, Irvine, California, USA
| | - Andrea Sorensen
- Division of Geriatrics, Department of Medicine, University of California Los Angeles David Geffen School of Medicine, Los Angeles, California, USA
| | - Chad Wes A Villaflores
- Division of Geriatrics, Department of Medicine, University of California Los Angeles David Geffen School of Medicine, Los Angeles, California, USA
| | - John N Mafi
- Division of General Internal Medicine and Health Services Research, Department of Medicine, University of California Los Angeles David Geffen School of Medicine, Los Angeles, California, USA
| | - Sitaram S Vangala
- Department of Medicine Statistics Core, Division of General Internal Medicine and Health Services Research, University of California Los Angeles David Geffen School of Medicine, Los Angeles, California, USA
| | - Ira S Hofer
- Department of Anesthesiology and Perioperative Medicine, University of California Los Angeles David Geffen School of Medicine, Los Angeles, California, USA
| | - John D Bartlett
- Department of Ophthalmology, University of California Los Angeles David Geffen School of Medicine, Los Angeles, California, USA
| | - Eric M Cheng
- Department of Neurology, University of California Los Angeles David Geffen School of Medicine, Los Angeles, California, USA
| | - Victor F Duval
- Department of Anesthesiology and Perioperative Medicine, University of California Los Angeles David Geffen School of Medicine, Los Angeles, California, USA
| | | | - David Elashoff
- Department of Medicine Statistics Core, Division of General Internal Medicine and Health Services Research, University of California Los Angeles David Geffen School of Medicine, Los Angeles, California, USA
| | - Noah J Goldstein
- University of California Los Angeles David Geffen School of Medicine, Los Angeles, California, USA
- UCLA Anderson School of Management, Los Angeles, California, USA
| | - Joseph A Ladapo
- Division of General Internal Medicine and Health Services Research, Department of Medicine, University of California Los Angeles David Geffen School of Medicine, Los Angeles, California, USA
| | - James M Moore
- Department of Anesthesiology and Perioperative Medicine, University of California Los Angeles David Geffen School of Medicine, Los Angeles, California, USA
| | - Antonio M Pessegueiro
- Division of General Internal Medicine and Health Services Research, Department of Medicine, University of California Los Angeles David Geffen School of Medicine, Los Angeles, California, USA
| | - Suzanne B Shu
- SC Johnson College of Business at Cornell University, Ithaca, New York, USA
- The Charles H. Dyson School of Applied Economics and Management, Ithaca, New York, USA
| | - Samuel A Skootsky
- Division of General Internal Medicine and Health Services Research, Department of Medicine, University of California Los Angeles David Geffen School of Medicine, Los Angeles, California, USA
| | - Ashley Turner
- Pharmacogenomics, Mayo Clinic Rochester, Rochester, Minnesota, USA
| | - Catherine A Sarkisian
- Division of General Internal Medicine and Health Services Research, Department of Medicine, University of California Los Angeles David Geffen School of Medicine, Los Angeles, California, USA
- VA Greater Los Angeles Geriatric Research Education and Clinical Center, Los Angeles, California, USA
| |
Collapse
|
9
|
Bartlett JD, Smith CE, Hu Y, Ikeda A, Strauss M, Liang T, Hsu YH, Trout AH, McComb DW, Freeman RC, Simmer JP, Hu JCC. MMP20-generated amelogenin cleavage products prevent formation of fan-shaped enamel malformations. Sci Rep 2021; 11:10570. [PMID: 34012043 PMCID: PMC8134442 DOI: 10.1038/s41598-021-90005-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 04/27/2021] [Indexed: 11/09/2022] Open
Abstract
Dental enamel forms extracellularly as thin ribbons of amorphous calcium phosphate (ACP) that initiate on dentin mineral in close proximity to the ameloblast distal membrane. Secreted proteins are critical for this process. Enam-/- and Ambn-/- mice fail to form enamel. We characterize enamel ribbon formation in wild-type (WT), Amelx-/- and Mmp20-/- mouse mandibular incisors using focused ion beam scanning electron microscopy (FIB-SEM) in inverted backscatter mode. In Amelx-/- mice, initial enamel mineral ribbons extending from dentin are similar in form to those of WT mice. As early enamel development progresses, the Amelx-/- mineral ribbons develop multiple branches, resembling the staves of a Japanese fan. These striking fan-shaped structures cease growing after attaining ~ 20 µm of enamel thickness (WT is ~ 120 µm). The initial enamel mineral ribbons in Mmp20-/- mice, like those of the Amelx-/- and WT, extend from the dentin surface to the ameloblast membrane, but appear to be fewer in number and coated on their sides with organic material. Remarkably, Mmp20-/- mineral ribbons also form fan-like structures that extend to ~ 20 µm from the dentin surface. However, these fans are subsequently capped with a hard, disorganized outer mineral layer. Amelogenin cleavage products are the only matrix components absent in both Amelx-/- and Mmp20-/- mice. We conclude that MMP20 and amelogenin are not critical for enamel mineral ribbon initiation, orientation, or initial shape. The pathological fan-like plates in these mice may form from the lack of amelogenin cleavage products, which appear necessary to form ordered hydroxyapatite.
Collapse
Affiliation(s)
- John D Bartlett
- Division of Biosciences, Ohio State University College of Dentistry, Columbus, OH, USA
| | - Charles E Smith
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, 1210 Eisenhower Pl, Ann Arbor, MI, 48108, USA
- Department of Anatomy and Cell Biology, Faculty of Medicine and Health Sciences, McGill University, Montreal, QC, Canada
| | - Yuanyuan Hu
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, 1210 Eisenhower Pl, Ann Arbor, MI, 48108, USA
| | - Atsushi Ikeda
- Division of Biosciences, Ohio State University College of Dentistry, Columbus, OH, USA
| | - Mike Strauss
- Department of Anatomy and Cell Biology, Faculty of Medicine and Health Sciences, McGill University, Montreal, QC, Canada
| | - Tian Liang
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, 1210 Eisenhower Pl, Ann Arbor, MI, 48108, USA
| | - Ya-Hsiang Hsu
- Department of Materials Science and Engineering, Ohio State University College of Engineering, Columbus, OH, USA
- Center for Electron Microscopy and Analysis, Ohio State University, Columbus, OH, USA
| | - Amanda H Trout
- Department of Materials Science and Engineering, Ohio State University College of Engineering, Columbus, OH, USA
- Center for Electron Microscopy and Analysis, Ohio State University, Columbus, OH, USA
| | - David W McComb
- Department of Materials Science and Engineering, Ohio State University College of Engineering, Columbus, OH, USA
- Center for Electron Microscopy and Analysis, Ohio State University, Columbus, OH, USA
| | - Rebecca C Freeman
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, 1210 Eisenhower Pl, Ann Arbor, MI, 48108, USA
| | - James P Simmer
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, 1210 Eisenhower Pl, Ann Arbor, MI, 48108, USA.
| | - Jan C-C Hu
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, 1210 Eisenhower Pl, Ann Arbor, MI, 48108, USA
| |
Collapse
|
10
|
Fujiwara N, Whitford GM, Bartlett JD, Suzuki M. Curcumin suppresses cell growth and attenuates fluoride-mediated Caspase-3 activation in ameloblast-like LS8 cells. Environ Pollut 2021; 273:116495. [PMID: 33486250 PMCID: PMC8272738 DOI: 10.1016/j.envpol.2021.116495] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Revised: 12/10/2020] [Accepted: 01/08/2021] [Indexed: 05/30/2023]
Abstract
The trace element fluoride can be beneficial for oral health by preventing dental caries. However, fluoride is also known as an environmental pollutant. Fluoride pollution can lead to fluoride over-ingestion and can cause health issues, including dental fluorosis. Curcumin attenuated fluoride-induced toxicity in animal models, however the molecular mechanisms of how curcumin affects fluoride toxicity remain to be elucidated. We hypothesized that curcumin attenuates fluoride toxicity through modulation of Ac-p53. Here we investigated how curcumin affects the p53-p21 pathway in fluoride toxicity. LS8 cells were treated with NaF with/without curcumin. Curcumin significantly increased phosphorylation of Akt [Thr308] and attenuated fluoride-mediated caspase-3 cleavage and DNA damage marker γH2AX expression. Curcumin-mediated attenuation of caspase-3 activation was reversed by Akt inhibitor LY294002 (LY). However, LY did not alter curcumin-mediated γH2AX suppression. These results suggest that curcumin inhibited fluoride-mediated apoptosis via Akt activation, but DNA damage was suppressed by other pathways. Curcumin did not suppress/alter fluoride-mediated Ac-p53. However, curcumin itself significantly increased Ac-p53 and upregulated p21 protein levels to suppress cell proliferation in a dose-dependent manner. Curcumin suppressed fluoride-induced phosphorylation of p21 and increased p21 levels within the nuclear fraction. However, curcumin did not reverse fluoride-mediated cell growth inhibition. These results suggest that curcumin-induced Ac-p53 and p21 led to cell cycle arrest, while curcumin attenuated fluoride-mediated apoptosis via activation of Akt and suppressed fluoride-mediated DNA damage. By inhibiting DNA damage and apoptosis, curcumin may potentially alleviate health issues caused by fluoride pollution. Further studies are required to better understand the mechanism of curcumin-induced biological effects on fluoride toxicity.
Collapse
Affiliation(s)
- Natsumi Fujiwara
- Department of Oral Biology and Diagnostic Sciences, The Dental College of Georgia, Augusta University, Augusta, GA, 30912, USA.
| | - Gary M Whitford
- Department of Oral Biology and Diagnostic Sciences, The Dental College of Georgia, Augusta University, Augusta, GA, 30912, USA.
| | - John D Bartlett
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, 43210, USA.
| | - Maiko Suzuki
- Department of Oral Biology and Diagnostic Sciences, The Dental College of Georgia, Augusta University, Augusta, GA, 30912, USA.
| |
Collapse
|
11
|
Jafri A, Prieto A, Gashau H, Bartlett JD. Thrombotic thrombocytopenia following ChAdOx1 nCov-19 vaccination. Acute Med 2021; 20:223-226. [PMID: 34679140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Serious thromboembolic events with concurrent thrombocytopenia, sometimes accompanied by bleeding, have occurred very rarely following administration of the ChAdOx1 nCoV-19 vaccine. We report the case of a 59-year-old male with an unremarkable medical history who presented to the emergency department with increasing breathlessness five days after receiving the first dose of ChAdOx1 nCov-19. The patient's blood results showed mild thrombocytopenia and a very high D-dimer, and a pulmonary embolism was confirmed through a CT pulmonary angiogram, which led to a provisional diagnosis of vaccine-induced immune thrombotic thrombocytopenia. The condition was then treated with immunoglobulin and intravenous argatroban in line with the guidance from the Expert Haematology Panel focussed on Vaccine-induced Thrombosis and Thrombocytopenia before conversion to apixaban.
Collapse
Affiliation(s)
- A Jafri
- MuDr, Senior Clinical Fellow in Acute Medicine, Hereford County Hospital
| | - A Prieto
- MPharm, Clinical Pharmacist, Hereford County Hospital
| | - Hde Gashau
- MuDr, Clinical Fellow in Respiratory Medicine, Hereford County Hospital
| | - J D Bartlett
- MBBS, BSc, FRCP, Lead Consultant for Acute Medicine, Hereford County Hospital
| |
Collapse
|
12
|
Wang SK, Zhang H, Chavez MB, Hu Y, Seymen F, Koruyucu M, Kasimoglu Y, Colvin CD, Kolli TN, Tan MH, Wang YL, Lu PY, Kim JW, Foster BL, Bartlett JD, Simmer JP, Hu JCC. Dental malformations associated with biallelic MMP20 mutations. Mol Genet Genomic Med 2020; 8:e1307. [PMID: 32495503 PMCID: PMC7434610 DOI: 10.1002/mgg3.1307] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 04/07/2020] [Accepted: 04/08/2020] [Indexed: 12/30/2022] Open
Abstract
Background Matrix metallopeptidase 20 (MMP20) is an evolutionarily conserved protease that is essential for processing enamel matrix proteins during dental enamel formation. MMP20 mutations cause human autosomal recessive pigmented hypomaturation‐type amelogenesis imperfecta (AI2A2; OMIM #612529). MMP20 is expressed in both odontoblasts and ameloblasts, but its function during dentinogenesis is unclear. Methods We characterized 10 AI kindreds with MMP20 defects, characterized human third molars and/or Mmp20−/− mice by histology, Backscattered Scanning Electron Microscopy (bSEM), µCT, and nanohardness testing. Results We identified six novel MMP20 disease‐causing mutations. Four pathogenic variants were associated with exons encoding the MMP20 hemopexin‐like (PEX) domain, suggesting a necessary regulatory function. Mutant human enamel hardness was softest (13% of normal) midway between the dentinoenamel junction (DEJ) and the enamel surface. bSEM and µCT analyses of the third molars revealed reduced mineral density in both enamel and dentin. Dentin close to the DEJ showed an average hardness number 62%–69% of control. Characterization of Mmp20−/− mouse dentin revealed a significant reduction in dentin thickness and mineral density and a transient increase in predentin thickness, indicating disturbances in dentin matrix secretion and mineralization. Conclusion These results expand the spectrum of MMP20 disease‐causing mutations and provide the first evidence for MMP20 function during dentin formation.
Collapse
Affiliation(s)
- Shih-Kai Wang
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, MI, USA.,Department of Pediatric Dentistry, National Taiwan University School of Dentistry, Taipei City, Taiwan R.O.C
| | - Hong Zhang
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, MI, USA
| | - Michael B Chavez
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - Yuanyuan Hu
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, MI, USA
| | - Figen Seymen
- Department of Pedodontics, Istanbul University Faculty of Dentistry, Istanbul, Turkey
| | - Mine Koruyucu
- Department of Pedodontics, Istanbul University Faculty of Dentistry, Istanbul, Turkey
| | - Yelda Kasimoglu
- Department of Pedodontics, Istanbul University Faculty of Dentistry, Istanbul, Turkey
| | - Connor D Colvin
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - Tamara N Kolli
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - Michelle H Tan
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - Yin-Lin Wang
- Department of Pediatric Dentistry, National Taiwan University School of Dentistry, Taipei City, Taiwan R.O.C
| | - Pei-Ying Lu
- Department of Pediatric Dentistry, National Taiwan University School of Dentistry, Taipei City, Taiwan R.O.C
| | - Jung-Wook Kim
- Department of Pediatric Dentistry & Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Republic of Korea.,Department of Molecular Genetics & Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Republic of Korea
| | - Brian L Foster
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - John D Bartlett
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - James P Simmer
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, MI, USA
| | - Jan C-C Hu
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, MI, USA
| |
Collapse
|
13
|
Deng H, Fujiwara N, Cui H, Whitford GM, Bartlett JD, Suzuki M. Histone acetyltransferase promotes fluoride toxicity in LS8 cells. Chemosphere 2020; 247:125825. [PMID: 31927229 PMCID: PMC7863547 DOI: 10.1016/j.chemosphere.2020.125825] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Revised: 12/31/2019] [Accepted: 01/02/2020] [Indexed: 05/30/2023]
Abstract
Previously we demonstrated that fluoride increased acetylated-p53 (Ac-p53) in LS8 cells that are derived from mouse enamel organ epithelia and in rodent ameloblasts. However, how p53 is acetylated by fluoride and how the p53 upstream molecular pathway responds to fluoride is not well characterized. Here we demonstrate that fluoride activates histone acetyltransferases (HATs) including CBP, p300, PCAF and Tip60 to acetylate p53. HAT activity is regulated by post-translational modifications such as acetylation and phosphorylation. HAT proteins and their post-translational modifications (p300, Acetyl-p300, CBP, Acetyl-CBP, Tip60 and phospho-Tip60) were analyzed by Western blots. p53-HAT binding was detected by co-immunoprecipitation (co-IP). Cell growth inhibition was analyzed by MTT assays. LS8 cells were treated with NaF with/without HAT inhibitors MG149 (Tip60 inhibitor) and Anacardic Acid (AA; inhibits p300/CBP and PCAF). MG149 or AA was added 1 h prior to NaF treatment. Co-IP results showed that NaF increased p53-CBP binding and p53-PCAF binding. NaF increased active Acetyl-p300, Acetyl-CBP and phospho-Tip60 levels, suggesting that fluoride activates these HATs. Fluoride-induced phospho-Tip60 was decreased by MG149. MG149 or AA treatment reversed fluoride-induced cell growth inhibition at 24 h. MG149 or AA treatment decreased fluoride-induced p53 acetylation to inhibit caspase-3 cleavage, DNA damage marker γH2AX expression and cytochrome-c release into the cytosol. These results suggest that acetylation of p53 by HATs contributes, at least in part, to fluoride-induced toxicity in LS8 cells via cell growth inhibition, apoptosis, DNA damage and mitochondrial damage. Modulation of HAT activity may, therefore, be a potential therapeutic target to mitigate fluoride toxicity in ameloblasts.
Collapse
Affiliation(s)
- Huidan Deng
- College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu, Sichuan, 611130, China.
| | - Natsumi Fujiwara
- Department of Oral Biology and Diagnostic Sciences, The Dental College of Georgia, Augusta University, Augusta, GA, 30912, USA.
| | - Hengmin Cui
- College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu, Sichuan, 611130, China.
| | - Gary M Whitford
- Department of Oral Biology and Diagnostic Sciences, The Dental College of Georgia, Augusta University, Augusta, GA, 30912, USA.
| | - John D Bartlett
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, 43210, USA.
| | - Maiko Suzuki
- Department of Oral Biology and Diagnostic Sciences, The Dental College of Georgia, Augusta University, Augusta, GA, 30912, USA.
| |
Collapse
|
14
|
Simmer JP, Hardy NC, Chinoy AF, Bartlett JD, Hu JCC. How Fluoride Protects Dental Enamel from Demineralization. J Int Soc Prev Community Dent 2020; 10:134-141. [PMID: 32670900 PMCID: PMC7339990 DOI: 10.4103/jispcd.jispcd_406_19] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 10/31/2019] [Accepted: 12/24/2019] [Indexed: 12/16/2022] Open
Abstract
Introduction: How fluoride (F–) protects dental enamel from caries is here conveyed to dental health-care providers by making simplifying approximations that accurately convey the essential principles, without obscuring them in a myriad of qualifications. Materials and Methods: We approximate that dental enamel is composed of calcium hydroxyapatite (HAP), a sparingly soluble ionic solid with the chemical formula Ca10(PO4)6(OH)2. Results: The electrostatic forces binding ionic solids together are described by Coulomb’s law, which shows that attractions between opposite charges increase greatly as their separation decreases. Relatively large phosphate ions (PO43–) dominate the structure of HAP, which approximates a hexagonal close-packed structure. The smaller Ca2+ and OH– ions fit into the small spaces (interstices) between phosphates, slightly expanding the close-packed structure. F– ions are smaller than OH– ions, so substituting F– for OH– allows packing the same number of ions into a smaller volume, increasing their forces of attraction. Dental decay results from tipping the solubility equilibrium Ca10(PO4)6(OH)2 (s) ⇔ 10Ca2+ (aq) + 6PO42– (aq) + 2OH– (aq) toward dissolution. HAP dissolves when the product of its ion concentrations, [Ca2+]10×[PO43–]6×[OH–]2, falls below the solubility product constant (Ksp) for HAP. Conclusion: Because of its more compact crystal structure, the Ksp for fluorapatite (FAP) is lower than the Ksp for HAP, so its ion product, [Ca2+]10×[PO43–]6×[F–]2, must fall further before demineralization can occur. Lowering the pH of the fluid surrounding enamel greatly reduces [PO43–] (lowering the ion products of HAP and FAP equally), but [OH–] falls much more rapidly than [F–], so FAP better resists acid attack.
Collapse
Affiliation(s)
- James Patrick Simmer
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, Michigan, USA
| | - Nina C Hardy
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, Michigan, USA
| | - Afriti F Chinoy
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, Michigan, USA
| | - John D Bartlett
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, Ohio, USA
| | - Jan C-C Hu
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, Michigan, USA
| |
Collapse
|
15
|
Sukseree S, Schwarze UY, Gruber R, Gruber F, Quiles Del Rey M, Mancias JD, Bartlett JD, Tschachler E, Eckhart L. ATG7 is essential for secretion of iron from ameloblasts and normal growth of murine incisors during aging. Autophagy 2020; 16:1851-1857. [PMID: 31880208 DOI: 10.1080/15548627.2019.1709764] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The incisors of rodents comprise an iron-rich enamel and grow throughout adult life, making them unique models of iron metabolism and tissue homeostasis during aging. Here, we deleted Atg7 (autophagy related 7) in murine ameloblasts, i.e. the epithelial cells that produce enamel. The absence of ATG7 blocked the transport of iron from ameloblasts into the maturing enamel, leading to a white instead of yellow surface of maxillary incisors. In aging mice, lack of ATG7 was associated with the growth of ectopic incisors inside severely deformed primordial incisors. These results suggest that 2 characteristic features of rodent incisors, i.e. deposition of iron on the enamel surface and stable growth during aging, depend on autophagic activity in ameloblasts. Abbreviations: ATG5: autophagy related 5; ATG7: autophagy related 7; CMV: cytomegalovirus; Cre: Cre recombinase; CT: computed tomography; FTH1: ferritin heavy polypeptide 1; GFP: green fluorescent protein; KRT5: keratin 5; KRT14: keratin 14; LGALS3: lectin, galactose binding, soluble 3; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; NCOA4: nuclear receptor coactivator 4; NRF2: nuclear factor, erythroid 2 like 2; SQSTM1: sequestosome 1.
Collapse
Affiliation(s)
- Supawadee Sukseree
- Research Division of Biology and Pathobiology of the Skin, Department of Dermatology, Medical University of Vienna , Vienna, Austria
| | | | - Reinhard Gruber
- Department of Oral Biology, Medical University of Vienna , Vienna, Austria
| | - Florian Gruber
- Research Division of Biology and Pathobiology of the Skin, Department of Dermatology, Medical University of Vienna , Vienna, Austria
| | - Maria Quiles Del Rey
- Division of Genomic Stability and DNA Repair, Department of Radiation Oncology, Dana-Farber Cancer Institute , Boston, MA, USA
| | - Joseph D Mancias
- Division of Genomic Stability and DNA Repair, Department of Radiation Oncology, Dana-Farber Cancer Institute , Boston, MA, USA
| | - John D Bartlett
- Division of Biosciences, College of Dentistry, The Ohio State University , Columbus, OH, USA
| | - Erwin Tschachler
- Research Division of Biology and Pathobiology of the Skin, Department of Dermatology, Medical University of Vienna , Vienna, Austria
| | - Leopold Eckhart
- Research Division of Biology and Pathobiology of the Skin, Department of Dermatology, Medical University of Vienna , Vienna, Austria
| |
Collapse
|
16
|
Deng H, Ikeda A, Cui H, Bartlett JD, Suzuki M. MDM2-Mediated p21 Proteasomal Degradation Promotes Fluoride Toxicity in Ameloblasts. Cells 2019; 8:E436. [PMID: 31083332 PMCID: PMC6562432 DOI: 10.3390/cells8050436] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 05/06/2019] [Accepted: 05/09/2019] [Indexed: 01/22/2023] Open
Abstract
Fluoride overexposure is an environmental health hazard and can cause enamel and skeletal fluorosis. Previously we demonstrated that fluoride increased acetylated-p53 and its downstream target p21 in ameloblast-derived LS8 cells. However, p21 function in fluoride toxicity is not well characterized. This study seeks to gain a better understanding of how p53 down-stream mediators, p21 and MDM2, respond to fluoride toxicity. LS8 cells were treated with NaF with/without MG-132 (proteasome inhibitor) or Nutlin-3a (MDM2 antagonist). NaF treatment for 2-6 h increased phospho-p21, which can inhibit apoptosis. However, phospho-p21 and p21 were decreased by NaF at 24 h, even though p21 mRNA was significantly increased at this time point. MG-132 reversed the fluoride-mediated p21 decrease, indicating that fluoride facilitates p21 proteasomal degradation. MG-132 suppressed fluoride-induced caspase-3 cleavage, suggesting that the proteasome plays a pro-apoptotic role in fluoride toxicity. NaF increased phospho-MDM2 in vitro and in mouse ameloblasts in vivo. Nutlin-3a suppressed NaF-mediated MDM2-p21 binding to reverse p21 degradation which increased phospho-p21. This suppressed apoptosis after 24 h NaF treatment. These results suggest that MDM2-mediated p21 proteasomal degradation with subsequent phospho-p21 attenuation contributes to fluoride-induced apoptosis. Inhibition of MDM2-mediated p21 degradation may be a potential therapeutic target to mitigate fluoride toxicity.
Collapse
Affiliation(s)
- Huidan Deng
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH 43210, USA.
- College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu 611130, China.
| | - Atsushi Ikeda
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH 43210, USA.
| | - Hengmin Cui
- College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu 611130, China.
| | - John D Bartlett
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH 43210, USA.
| | - Maiko Suzuki
- Department of Oral Biology and Diagnostic Sciences, The Dental College of Georgia, Augusta University, Augusta, GA 30912, USA.
| |
Collapse
|
17
|
Kim J, Zhang H, Seymen F, Koruyucu M, Hu Y, Kang J, Kim YJ, Ikeda A, Kasimoglu Y, Bayram M, Zhang C, Kawasaki K, Bartlett JD, Saunders TL, Simmer JP, Hu JC. Mutations in RELT cause autosomal recessive amelogenesis imperfecta. Clin Genet 2019; 95:375-383. [PMID: 30506946 PMCID: PMC6392136 DOI: 10.1111/cge.13487] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Revised: 11/26/2018] [Accepted: 11/27/2018] [Indexed: 12/16/2022]
Abstract
Amelogenesis imperfecta (AI) is a collection of isolated (non-syndromic) inherited diseases affecting dental enamel formation or a clinical phenotype in syndromic conditions. We characterized three consanguineous AI families with generalized irregular hypoplastic enamel with rapid attrition that perfectly segregated with homozygous defects in a novel gene: RELT that is a member of the tumor necrosis factor receptor superfamily (TNFRSF). RNAscope in situ hybridization of wild-type mouse molars and incisors showed specific Relt mRNA expression by secretory stage ameloblasts and by odontoblasts. Relt-/- mice generated by CRISPR/Cas9 exhibited incisor and molar enamel malformations. Relt-/- enamel had a rough surface and underwent rapid attrition. Normally unmineralized spaces in the deep enamel near the dentino-enamel junction (DEJ) were as highly mineralized as the adjacent enamel, which likely altered the mechanical properties of the DEJ. Phylogenetic analyses showed the existence of selective pressure on RELT gene outside of tooth development, indicating that the human condition may be syndromic, which possibly explains the history of small stature and severe childhood infections in two of the probands. Knowing a TNFRSF member is critical during the secretory stage of enamel formation advances our understanding of amelogenesis and improves our ability to diagnose human conditions featuring enamel malformations.
Collapse
Affiliation(s)
- Jung‐Wook Kim
- Department of Pediatric Dentistry & Dental Research Institute, School of DentistrySeoul National UniversitySeoulRepublic of Korea
- Department of Molecular Genetics & the Dental Research Institute, School of DentistrySeoul National UniversitySeoulRepublic of Korea
| | - Hong Zhang
- Department of Biologic and Materials SciencesUniversity of Michigan School of DentistryAnn ArborMichigan
| | - Figen Seymen
- Department of Pedodontics, Faculty of DentistryIstanbul UniversityIstanbulTurkey
| | - Mine Koruyucu
- Department of Pedodontics, Faculty of DentistryIstanbul UniversityIstanbulTurkey
| | - Yuanyuan Hu
- Department of Biologic and Materials SciencesUniversity of Michigan School of DentistryAnn ArborMichigan
| | - Jenny Kang
- Department of Pediatric Dentistry & Dental Research Institute, School of DentistrySeoul National UniversitySeoulRepublic of Korea
| | - Youn J. Kim
- Department of Molecular Genetics & the Dental Research Institute, School of DentistrySeoul National UniversitySeoulRepublic of Korea
| | - Atsushi Ikeda
- Division of BiosciencesThe Ohio State University, College of DentistryColumbusOhio
| | - Yelda Kasimoglu
- Department of Pedodontics, Faculty of DentistryIstanbul UniversityIstanbulTurkey
| | - Merve Bayram
- Department of Pedodontics, Faculty of DentistryIstanbul Medipol UniversityIstanbulTurkey
| | - Chuhua Zhang
- Department of Biologic and Materials SciencesUniversity of Michigan School of DentistryAnn ArborMichigan
| | - Kazuhiko Kawasaki
- Department of AnthropologyPenn State UniversityUniversity ParkPennsylvania
| | - John D. Bartlett
- Division of BiosciencesThe Ohio State University, College of DentistryColumbusOhio
| | - Thomas L. Saunders
- Department of Internal Medicine, Division of Molecular, Medicine and GeneticsUniversity of Michigan Medical SchoolAnn ArborMichigan
| | - James P. Simmer
- Department of Biologic and Materials SciencesUniversity of Michigan School of DentistryAnn ArborMichigan
| | - Jan C‐C. Hu
- Department of Biologic and Materials SciencesUniversity of Michigan School of DentistryAnn ArborMichigan
| |
Collapse
|
18
|
Abstract
Aims The aim of this study was to assess the current evidence relating to the benefits of virtual reality (VR) simulation in orthopaedic surgical training, and to identify areas of future research. Materials and Methods A literature search using the MEDLINE, Embase, and Google Scholar databases was performed. The results' titles, abstracts, and references were examined for relevance. Results A total of 31 articles published between 2004 and 2016 and relating to the objective validity and efficacy of specific virtual reality orthopaedic surgical simulators were identified. We found 18 studies demonstrating the construct validity of 16 different orthopaedic virtual reality simulators by comparing expert and novice performance. Eight studies have demonstrated skill acquisition on a simulator by showing improvements in performance with repeated use. A further five studies have demonstrated measurable improvements in operating theatre performance following a period of virtual reality simulator training. Conclusion The demonstration of 'real-world' benefits from the use of VR simulation in knee and shoulder arthroscopy is promising. However, evidence supporting its utility in other forms of orthopaedic surgery is lacking. Further studies of validity and utility should be combined with robust analyses of the cost efficiency of validated simulators to justify the financial investment required for their use in orthopaedic training. Cite this article: Bone Joint J 2018;100-B:559-65.
Collapse
Affiliation(s)
- J D Bartlett
- Cambridge University School of Clinical Medicine, Addenbrooke's Hospital, Cambridge, UK
| | - J E Lawrence
- Department of Trauma and Orthopaedics, Addenbrooke's Hospital, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
| | - M E Stewart
- Cambridge University School of Clinical Medicine, Addenbrooke's Hospital
| | - N Nakano
- Department of Trauma and Orthopaedics, Addenbrooke's Hospital, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
| | - V Khanduja
- Department of Trauma and Orthopaedics, Addenbrooke's Hospital, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
| |
Collapse
|
19
|
Abstract
Ameloblasts responsible for enamel formation express matrix metalloproteinase 20 (MMP20), an enzyme that cleaves enamel matrix proteins, including amelogenin (AMELX) and ameloblastin (AMBN). Previously, we showed that continuously erupting incisors from transgenic mice overexpressing active MMP20 had a massive cell infiltrate present within their enamel space, leading to enamel mineralization defects. However, effects of MMP20 overexpression on mouse molars were not analyzed, although these teeth more accurately represent human odontogenesis. Therefore, MMP20-overexpressing mice ( Mmp20+/+Tg+) were assessed by multiscale analyses, combining several approaches from high-resolution micro-computed tomography to enamel organ immunoblots. During the secretory stage at postnatal day 6 (P6), Mmp20+/+Tg+ mice had a discontinuous ameloblast layer and, unlike incisors, molar P12 maturation stage ameloblasts abnormally migrated away from the enamel layer into the stratum intermedium/stellate reticulum. TOPflash assays performed in vitro demonstrated that MMP20 expression promoted β-catenin nuclear localization and that MMP20 expression promoted invasion through Matrigel-coated filters. However, for both assays, significant differences were eliminated in the presence of the β-catenin inhibitor ICG-001. This suggests that MMP20 activity promotes cell migration via the Wnt pathway. In vivo, the unique molar migration of amelogenin-expressing ameloblasts was associated with abnormal deposition of ectopic calcified nodules surrounding the adherent enamel layer. Enamel content was assessed just prior to eruption at P15. Compared to wild-type, Mmp20+/+Tg+ molars exhibited significant reductions in enamel thickness (70%), volume (60%), and mineral density (40%), and MMP20 overexpression resulted in premature cleavage of AMBN, which likely contributed to the severe defects in enamel mineralization. In addition, Mmp20+/+Tg+ mouse molar enamel organs had increased levels of inactive p-cofilin, a protein that regulates cell polarity. These data demonstrate that increased MMP20 activity in molars causes premature degradation of ameloblastin and inactivation of cofilin, which may contribute to pathological Wnt-mediated cell migration away from the enamel layer.
Collapse
Affiliation(s)
- M Shin
- 1 Fukuoka Dental College, Sawara-ku, Fukuoka, Japan
| | - M B Chavez
- 2 Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - A Ikeda
- 2 Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - B L Foster
- 2 Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - J D Bartlett
- 2 Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, USA
| |
Collapse
|
20
|
Suzuki M, Ikeda A, Bartlett JD. Sirt1 overexpression suppresses fluoride-induced p53 acetylation to alleviate fluoride toxicity in ameloblasts responsible for enamel formation. Arch Toxicol 2017; 92:1283-1293. [PMID: 29185024 DOI: 10.1007/s00204-017-2135-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 11/23/2017] [Indexed: 12/21/2022]
Abstract
Low-dose fluoride is an effective caries prophylactic, but high-dose fluoride is an environmental health hazard that causes skeletal and dental fluorosis. Treatments to prevent fluorosis and the molecular pathways responsive to fluoride exposure remain to be elucidated. Previously we showed that fluoride activates SIRT1 as an adaptive response to protect cells. Here, we demonstrate that fluoride induced p53 acetylation (Ac-p53) [Lys379], which is a SIRT1 deacetylation target, in ameloblast-derived LS8 cells in vitro and in enamel organ in vivo. Here we assessed SIRT1 function on fluoride-induced Ac-p53 formation using CRISPR/Cas9-mediated Sirt1 knockout (LS8Sirt/KO) cells or CRISPR/dCas9/SAM-mediated Sirt1 overexpressing (LS8Sirt1/over) cells. NaF (5 mM) induced Ac-p53 formation and increased cell cycle arrest via Cdkn1a/p21 expression in Wild-type (WT) cells. However, fluoride-induced Ac-p53 was suppressed by the SIRT1 activator resveratrol (50 µM). Without fluoride, Ac-p53 persisted in LS8Sirt/KO cells, whereas it decreased in LS8Sirt1/over. Fluoride-induced Ac-p53 formation was also suppressed in LS8Sirt1/over cells. Compared to WT cells, fluoride-induced Cdkn1a/p21 expression was elevated in LS8Sirt/KO and these cells were more susceptible to fluoride-induced growth inhibition. In contrast, LS8Sirt1/over cells were significantly more resistant. In addition, fluoride-induced cytochrome-c release and caspase-3 activation were suppressed in LS8Sirt1/over cells. Fluoride induced expression of the DNA double strand break marker γH2AX in WT cells and this was augmented in LS8Sirt1/KO cells, but was attenuated in LS8Sirt1/over cells. Our results suggest that SIRT1 deacetylates Ac-p53 to mitigate fluoride-induced cell growth inhibition, mitochondrial damage, DNA damage and apoptosis. This is the first report implicating Ac-p53 in fluoride toxicity.
Collapse
Affiliation(s)
- Maiko Suzuki
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, 43210, USA
| | - Atsushi Ikeda
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, 43210, USA
| | - John D Bartlett
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, 43210, USA.
| |
Collapse
|
21
|
Suzuki M, Everett ET, Whitford GM, Bartlett JD. 4-phenylbutyrate Mitigates Fluoride-Induced Cytotoxicity in ALC Cells. Front Physiol 2017; 8:302. [PMID: 28553235 PMCID: PMC5425599 DOI: 10.3389/fphys.2017.00302] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Accepted: 04/25/2017] [Indexed: 12/13/2022] Open
Abstract
Chronic fluoride over-exposure during pre-eruptive enamel development can cause dental fluorosis. Severe dental fluorosis is characterized by porous, soft enamel that is vulnerable to erosion and decay. The prevalence of dental fluorosis among the population in the USA, India and China is increasing. Other than avoiding excessive intake, treatments to prevent dental fluorosis remain unknown. We previously reported that high-dose fluoride induces endoplasmic reticulum (ER) stress and oxidative stress in ameloblasts. Cell stress induces gene repression, mitochondrial damage and apoptosis. An aromatic fatty acid, 4-phenylbutyrate (4PBA) is a chemical chaperone that interacts with misfolded proteins to prevent ER stress. We hypothesized that 4PBA ameliorates fluoride-induced ER stress in ameloblasts. To determine whether 4PBA protects ameloblasts from fluoride toxicity, we analyzed gene expression of Tgf-β1, Bcl2/Bax ratio and cytochrome-c release in vitro. In vivo, we measured fluorosis levels, enamel hardness and fluoride concentration. Fluoride treated Ameloblast-lineage cells (ALC) had decreased Tgf-β1 expression and this was reversed by 4PBA treatment. The anti-apoptotic Blc2/Bax ratio was significantly increased in ALC cells treated with fluoride/4PBA compared to fluoride treatment alone. Fluoride treatment induced cytochrome-c release from mitochondria into the cytosol and this was inhibited by 4PBA treatment. These results suggest that 4PBA mitigates fluoride-induced gene suppression, apoptosis and mitochondrial damage in vitro. In vivo, C57BL/6J mice were provided fluoridated water for six weeks with either fluoride free control-chow or 4PBA-containing chow (7 g/kg 4PBA). With few exceptions, enamel microhardness, fluorosis levels, and fluoride concentrations of bone and urine did not differ significantly between fluoride treated animals fed with control-chow or 4PBA-chow. Although 4PBA mitigated high-dose fluoride toxicity in vitro, a diet rich in 4PBA did not attenuate dental fluorosis in rodents. Perhaps, not enough intact 4PBA reaches the rodent ameloblasts necessary to reverse the effects of fluoride toxicity. Further studies will be required to optimize protocols for 4PBA administration in vivo in order to evaluate the effect of 4PBA on dental fluorosis.
Collapse
Affiliation(s)
- Maiko Suzuki
- Division of Biosciences, College of Dentistry, The Ohio State UniversityColumbus, OH, USA
| | - Eric T Everett
- Department of Pediatric Dentistry and The Carolina Center for Genome Sciences, University of North CarolinaChapel Hill, NC, USA
| | - Gary M Whitford
- Department of Oral Biology, College of Dental Medicine, Georgia Regents UniversityAugusta, GA, USA
| | - John D Bartlett
- Division of Biosciences, College of Dentistry, The Ohio State UniversityColumbus, OH, USA
| |
Collapse
|
22
|
Guan X, Xu M, Millar SE, Bartlett JD. Beta-catenin is essential for ameloblast movement during enamel development. Eur J Oral Sci 2016; 124:221-7. [PMID: 26957367 DOI: 10.1111/eos.12261] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/21/2016] [Indexed: 12/21/2022]
Abstract
Beta-catenin is a multifunctional protein that plays key roles in cadherin-based cell adherens junctions and in the Wnt signaling pathway. The canonical Wnt/β-catenin pathway can regulate transcription factors that control cell movement/invasion. We investigated whether β-catenin regulates ameloblast movement through canonical Wnt signaling. The morphological and physical properties of enamel were assessed in enamel from control and β-catenin conditional knockout (cKO) mice. Ameloblast-lineage cells (ALC) were used to investigate the potential roles of β-catenin in cell migration and in E-cadherin expression. Compared with controls, incisors from β-catenin cKO mice were short, blunt, and where enamel was present, it was soft and malformed. Scanning electron microscopy revealed a dysplastic rod pattern within the enamel of incisors from β-catenin cKO mice, and Vickers microhardness measurements confirmed that mice with β-catenin ablated from their enamel organ had enamel that was significantly softer than normal. Amelogenesis was disrupted in the absence of β-catenin and the ameloblasts did not differentiate properly. We further demonstrated that migration of ALCs was inhibited in vitro and that E-cadherin expression was significantly up-regulated when ALCs were treated with the β-catenin inhibitor, ICG-001. Beta-catenin ablation causes enamel malformation in mice and this phenotype may occur, in part, by a lack of ameloblast differentiation and/or movement necessary to form the decussating enamel rod structure.
Collapse
Affiliation(s)
- Xiaomu Guan
- Department of Mineralized Tissue Biology and Harvard School of Dental Medicine, Forsyth Institute, Cambridge, MA, USA
| | - Mingang Xu
- Departments of Dermatology and Cell & Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Sarah E Millar
- Departments of Dermatology and Cell & Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - John D Bartlett
- Division of Biosciences, College of Dentistry, Ohio State University, Columbus, OH, USA
| |
Collapse
|
23
|
Hu Y, Smith CE, Richardson AS, Bartlett JD, Hu JCC, Simmer JP. MMP20, KLK4, and MMP20/KLK4 double null mice define roles for matrix proteases during dental enamel formation. Mol Genet Genomic Med 2015; 4:178-96. [PMID: 27066511 PMCID: PMC4799876 DOI: 10.1002/mgg3.194] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 11/12/2015] [Accepted: 11/13/2015] [Indexed: 01/08/2023] Open
Abstract
Matrix metalloproteinase 20 (MMP20) and kallikrein‐related peptidase 4 (KLK4) are secreted proteinases that are essential for proper dental enamel formation. We characterized and compared enamel formed in wild‐type, Mmp20−/−, Klk4−/−, Mmp20+/−Klk4+/−, and Mmp20−/−Klk4−/− mice using dissecting and light microscopy, backscattered scanning electron microscopy (bSEM), SEM, microcomputed tomography (μCT), and energy‐dispersive X‐ray analysis (EDX). Following eruption, fractures were observed on Mmp20−/−, Klk4−/−, Mmp20+/−Klk4+/−, and Mmp20−/−Klk4−/− molars. Failure of the enamel in the Mmp20+/−Klk4+/− molars was unexpected and suggested that digenic effects could contribute to the etiology of amelogenesis imperfecta in humans. Micro‐CT analyses of hemimandibles demonstrated significantly reduced high‐density enamel volume in the Mmp20−/− and Klk4−/− mice relative to the wild‐type, which was further reduced in Mmp20−/−Klk4−/− mice. bSEM images of 7‐week Mmp20−/− and Mmp20−/−Klk4−/− mandibular incisors showed rough, pitted enamel surfaces with numerous indentations and protruding nodules. The Mmp20+/− and Mmp20+/−Klk4+/− incisors showed prominent, evenly spaced, horizontal ridges that were more distinct in Mmp20+/−Klk4+/− incisors relative to Mmp20+/− incisors due to the darkening of the valleys between the ridges. In cross sections, the Mmp20−/− and Mmp20−/−Klk4−/− exhibited three distinct layers. The outer layer exhibited a disturbed elemental composition and an irregular enamel surface covered with nodules. The Mmp20 null enamel was apparently unable to withstand the sheer forces associated with eruption and separated from dentin during development. Cells invaded the cracks and interposed between the dentin and enamel layers. MMP20 and KLK4 serve overlapping and complementary functions to harden enamel by removing protein, but MMP20 potentially serves multiple additional functions necessary for the adherence of enamel to dentin, the release of intercellular protein stores into the enamel matrix, the retreat of ameloblasts to facilitate thickening of the enamel layer, and the timely transition of ameloblasts to maturation.
Collapse
Affiliation(s)
- Yuanyuan Hu
- Departments of Biologic and Materials Sciences University of Michigan School of Dentistry 1210 Eisenhower Place Ann Arbor Michigan 48108
| | - Charles E Smith
- Departments of Biologic and Materials SciencesUniversity of Michigan School of Dentistry1210 Eisenhower PlaceAnn ArborMichigan48108; Facility for Electron Microscopy ResearchDepartment of Anatomy and Cell Biology and Faculty of DentistryMcGill UniversityMontrealQuebecH3A 2B2Canada
| | - Amelia S Richardson
- Departments of Biologic and Materials Sciences University of Michigan School of Dentistry 1210 Eisenhower Place Ann Arbor Michigan 48108
| | - John D Bartlett
- Office of Research College of Dentistry Ohio State University 4139 Postle Hall, 305 W. 12th Ave. Columbus Ohio 43210
| | - Jan C C Hu
- Departments of Biologic and Materials Sciences University of Michigan School of Dentistry 1210 Eisenhower Place Ann Arbor Michigan 48108
| | - James P Simmer
- Departments of Biologic and Materials Sciences University of Michigan School of Dentistry 1210 Eisenhower Place Ann Arbor Michigan 48108
| |
Collapse
|
24
|
Suzuki M, Bandoski C, Bartlett JD. Fluoride induces oxidative damage and SIRT1/autophagy through ROS-mediated JNK signaling. Free Radic Biol Med 2015; 89:369-78. [PMID: 26431905 PMCID: PMC4684823 DOI: 10.1016/j.freeradbiomed.2015.08.015] [Citation(s) in RCA: 160] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Revised: 08/20/2015] [Accepted: 08/28/2015] [Indexed: 02/07/2023]
Abstract
Fluoride is an effective caries prophylactic, but at high doses can also be an environmental health hazard. Acute or chronic exposure to high fluoride doses can result in dental enamel and skeletal and soft tissue fluorosis. Dental fluorosis is manifested as mottled, discolored, porous enamel that is susceptible to dental caries. Fluoride induces cell stress, including endoplasmic reticulum stress and oxidative stress, which leads to impairment of ameloblasts responsible for dental enamel formation. Recently we reported that fluoride activates SIRT1 and autophagy as an adaptive response to protect cells from stress. However, it still remains unclear how SIRT1/autophagy is regulated in dental fluorosis. In this study, we demonstrate that fluoride exposure generates reactive oxygen species (ROS) and the resulting oxidative damage is counteracted by SIRT1/autophagy induction through c-Jun N-terminal kinase (JNK) signaling in ameloblasts. In the mouse-ameloblast-derived cell line LS8, fluoride induced ROS, mitochondrial damage including cytochrome-c release, up-regulation of UCP2, attenuation of ATP synthesis, and H2AX phosphorylation (γH2AX), which is a marker of DNA damage. We evaluated the effects of the ROS inhibitor N-acetylcysteine (NAC) and the JNK inhibitor SP600125 on fluoride-induced SIRT1/autophagy activation. NAC decreased fluoride-induced ROS generation and attenuated JNK and c-Jun phosphorylation. NAC decreased SIRT1 phosphorylation and formation of the autophagy marker LC3II, which resulted in an increase in the apoptosis mediators γH2AX and cleaved/activated caspase-3. SP600125 attenuated fluoride-induced SIRT1 phosphorylation, indicating that fluoride activates SIRT1/autophagy via the ROS-mediated JNK pathway. In enamel organs from rats or mice treated with 50, 100, or 125 ppm fluoride for 6 weeks, cytochrome-c release and the DNA damage markers 8-oxoguanine, p-ATM, and γH2AX were increased compared to those in controls (0 ppm fluoride). These results suggest that fluoride-induced ROS generation causes mitochondrial damage and DNA damage, which may lead to impairment of ameloblast function. To counteract this impairment, SIRT1/autophagy is induced via JNK signaling to protect cells/ameloblasts from fluoride-induced oxidative damage that may cause dental fluorosis.
Collapse
Affiliation(s)
- Maiko Suzuki
- Department of Mineralized Tissue Biology, The Forsyth Institute & Harvard School of Dental Medicine, 245 First Street, Cambridge, MA
| | - Cheryl Bandoski
- Department of Mineralized Tissue Biology, The Forsyth Institute & Harvard School of Dental Medicine, 245 First Street, Cambridge, MA
| | - John D Bartlett
- Department of Mineralized Tissue Biology, The Forsyth Institute & Harvard School of Dental Medicine, 245 First Street, Cambridge, MA.
| |
Collapse
|
25
|
Affiliation(s)
- J D Bartlett
- Department of Mineralized Tissue Biology, The Forsyth Institute, Cambridge, MA, USA
| | - J P Simmer
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, MI, USA
| |
Collapse
|
26
|
Pugach MK, Ozer F, Mulmadgi R, Li Y, Suggs C, Wright JT, Bartlett JD, Gibson CW, Lindemeyer RG. Shear bond strength of dentin and deproteinized enamel of amelogenesis imperfecta mouse incisors. Pediatr Dent 2014; 36:130-136. [PMID: 25303500 PMCID: PMC4196710] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
PURPOSE The purposes of this study were to: (1) investigate adhesion through shear bond strength (SBS) testing of a resin composite bonded with a self-etching bonding system (SEB) to amelogenesis imperfecta (AI)-affected deproteinized mouse enamel or dentin; and (2) compare wild-type (WT), amelogenin null (AmelxKO), and matrix metalloproteinase-20 null (Mmp20KO) enamel and dentin phenotypes using micro-CT and nanoindentation. METHODS Enamel incisor surfaces of WT, AmelxKO, and Mmp20KO mice were treated with SEB with and without sodium hypochlorite and tested for SBS. Incisor dentin was also treated with SEB and tested for SBS. These surfaces were further examined by scanning electron miscroscopy. Micro-CT and nanoindentation analyses were performed on mouse dentin and enamel. Data were analyzed for significance by analysis of variance. RESULTS Deproteinization did not improve SBS of SEB to these AI-affected enamel surfaces. SBS of AmelxKO teeth was similar in dentin and enamel; however, it was higher in Mmp20KO dentin. The nanohardness of knockout enamel was significantly lower than WT, while knockout dentin nanohardness was not different from WT. CONCLUSIONS Using animal amelogenesis imperfecta models, enamel sodium hypochlorite deproteinization of hypoplastic and hypoplastic-hypomaturation enamel did not increase shear bond strength, while removal of the defective enamel allowed optimal dentin bonding.
Collapse
Affiliation(s)
- Megan K Pugach
- Department of Mineralized Tissue Biology, The Forsyth Institute, Cambridge, Mass., USA; Department of Developmental Biology, Harvard School of Dental Medicine, Boston, Mass., USA
| | - Fusun Ozer
- Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pa, USA
| | - Raj Mulmadgi
- Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pa, USA
| | - Yong Li
- Department of Anatomy and Cell Biology, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pa, USA
| | - Cynthia Suggs
- Department of Pediatric Dentistry, School of Dentistry, University of North Carolina, Chapel Hill, N.C., USA
| | - J Timothy Wright
- Department of Pediatric Dentistry, School of Dentistry, University of North Carolina, Chapel Hill, N.C., USA
| | - John D Bartlett
- Mineralized Tissue Biology, The Forsyth Institute, Cambridge, Mass., USA
| | - Carolyn W Gibson
- Department of Anatomy and Cell Biology, at the School of Dental Medicine, University of Pennsylvania, Philadelphia, Pa, USA
| | - Rochelle G Lindemeyer
- Department of Pediatric Dentistry, at the School of Dental Medicine, University of Pennsylvania, Philadelphia, Pa, USA.
| |
Collapse
|
27
|
Suzuki M, Sierant ML, Antone JV, Everett ET, Whitford GM, Bartlett JD. Uncoupling protein-2 is an antioxidant that is up-regulated in the enamel organ of fluoride-treated rats. Connect Tissue Res 2014; 55 Suppl 1:25-8. [PMID: 25158175 PMCID: PMC4145607 DOI: 10.3109/03008207.2014.923854] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Dental fluorosis is characterized by subsurface hypomineralization and retention of enamel matrix proteins. Fluoride (F(-)) exposure generates reactive oxygen species (ROS) that can cause endoplasmic reticulum (ER)-stress. We therefore screened oxidative stress arrays to identify genes regulated by F(-) exposure. Vitamin E is an antioxidant so we asked if a diet high in vitamin E would attenuate dental fluorosis. Maturation stage incisor enamel organs (EO) were harvested from F(-)-treated rats and mice were assessed to determine if vitamin E ameliorates dental fluorosis. Uncoupling protein-2 (Ucp2) was significantly up-regulated by F(-) (∼1.5 & 2.0 fold for the 50 or 100 ppm F(-) treatment groups, respectively). Immunohistochemical results on maturation stage rat incisors demonstrated that UCP2 protein levels increased with F(-) treatment. UCP2 down-regulates mitochondrial production of ROS, which decreases ATP production. Thus, in addition to reduced protein translation caused by ER-stress, a reduction in ATP production by UCP2 may contribute to the inability of ameloblasts to remove protein from the hardening enamel. Fluoride-treated mouse enamel had significantly higher quantitative fluorescence (QF) than the untreated controls. No significant QF difference was observed between control and vitamin E-enriched diets within a given F(-) treatment group. Therefore, a diet rich in vitamin E did not attenuate dental fluorosis. We have identified a novel oxidative stress response gene that is up-regulated in vivo by F(-) and activation of this gene may adversely affect ameloblast function.
Collapse
Affiliation(s)
- Maiko Suzuki
- Department of Mineralized Tissue Biology, The Forsyth Institute & Harvard School of Dental Medicine, 245 First Street, Cambridge, MA, USA
| | - Megan L. Sierant
- Department of Mineralized Tissue Biology, The Forsyth Institute & Harvard School of Dental Medicine, 245 First Street, Cambridge, MA, USA
| | - Jerry V. Antone
- Department of Mineralized Tissue Biology, The Forsyth Institute & Harvard School of Dental Medicine, 245 First Street, Cambridge, MA, USA
| | - Eric T. Everett
- Department of Pediatric Dentistry and The Carolina Center for Genome Sciences, University of North Carolina, Chapel Hill, NC, USA
| | - Gary M. Whitford
- Department of Oral Biology, College of Dental Medicine, Georgia Regents University, Augusta, GA, USA
| | - John D. Bartlett
- Department of Mineralized Tissue Biology, The Forsyth Institute & Harvard School of Dental Medicine, 245 First Street, Cambridge, MA, USA
| |
Collapse
|
28
|
Abstract
Dental fluorosis is caused by chronic high-level fluoride (F(-)) exposure during enamel development, and fluorosed enamel has a higher than normal protein content. Matrix metalloproteinase 20 cleaves enamel matrix proteins during the secretory stage, and KLK4 further cleaves these proteins during the maturation stage so that the proteins can be reabsorbed from the hardening enamel. We show that transforming growth factor β1 (TGF-β1) can induce Klk4 expression, and we examine the effect of F(-) on TGF-β1 and KLK4 expression. We found that in vivo F(-) inhibits Klk4 but not Mmp20 transcript levels. LacZ-C57BL/6-Klk4 (+/LacZ) mice have LacZ inserted in frame at the Klk4 translation initiation site so that the endogenous Klk4 promoter drives LacZ expression in the same temporal/spatial way as it does for Klk4. KLK4 protein levels in rat enamel and β-galactosidase staining in LacZ-C57BL/6-Klk4 (+/LacZ) mouse enamel were both significantly reduced by F(-) treatment. Since TGF-β1 induces KLK4 expression, we tested and found that F(-) significantly reduced Tgf-β1 transcript levels in rat enamel organ. These data suggest that F(-)-mediated downregulation of TGF-β1 expression contributes to reduced KLK4 protein levels in fluorosed enamel and provides an explanation for why fluorosed enamel has a higher than normal protein content.
Collapse
Affiliation(s)
- M Suzuki
- Department of Mineralized Tissue Biology, The Forsyth Institute, Cambridge, MA, USA, and Harvard School of Dental Medicine, Boston, MA, USA
| | - M Shin
- Department of Mineralized Tissue Biology, The Forsyth Institute, Cambridge, MA, USA, and Harvard School of Dental Medicine, Boston, MA, USA
| | - J P Simmer
- Department of Biological and Material Sciences, University of Michigan School of Dentistry, Ann Arbor, MI, USA
| | - J D Bartlett
- Department of Mineralized Tissue Biology, The Forsyth Institute, Cambridge, MA, USA, and Harvard School of Dental Medicine, Boston, MA, USA
| |
Collapse
|
29
|
Sarkar J, Simanian EJ, Tuggy SY, Bartlett JD, Snead ML, Sugiyama T, Paine ML. Comparison of two mouse ameloblast-like cell lines for enamel-specific gene expression. Front Physiol 2014; 5:277. [PMID: 25120490 PMCID: PMC4110967 DOI: 10.3389/fphys.2014.00277] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Accepted: 07/07/2014] [Indexed: 12/20/2022] Open
Abstract
Ameloblasts are ectoderm-derived cells that produce an extracellular enamel matrix that mineralizes to form enamel. The development and use of immortalized cell lines, with a stable phenotype, is an important contribution to biological studies as it allows for the investigation of molecular activities without the continuous need for animals. In this study we compare the expression profiles of enamel-specific genes in two mouse derived ameloblast-like cell lines: LS8 and ALC cells. Quantitative PCR analysis indicates that, relative to each other, LS8 cells express greater mRNA levels for genes that define secretory-stage activities (Amelx, Ambn, Enam, and Mmp20), while ALC express greater mRNA levels for genes that define maturation-stage activities (Odam and Klk4). Western blot analyses show that Amelx, Ambn, and Odam proteins are detectable in ALC, but not LS8 cells. Unstimulated ALC cells form calcified nodules, while LS8 cells do not. These data provide greater insight as to the suitability of both cell lines to contribute to biological studies on enamel formation and biomineralization, and highlight some of the strengths and weaknesses when relying on enamel epithelial organ-derived cell lines to study molecular activities of amelogenesis.
Collapse
Affiliation(s)
- Juni Sarkar
- Center for Craniofacial Molecular Biology, Division of Biomedical Sciences, Herman Ostrow School of Dentistry of USC, University of Southern California Los Angeles, CA, USA
| | - Emil J Simanian
- Center for Craniofacial Molecular Biology, Division of Biomedical Sciences, Herman Ostrow School of Dentistry of USC, University of Southern California Los Angeles, CA, USA
| | - Sarah Y Tuggy
- Center for Craniofacial Molecular Biology, Division of Biomedical Sciences, Herman Ostrow School of Dentistry of USC, University of Southern California Los Angeles, CA, USA
| | - John D Bartlett
- Department of Mineralized Tissue Biology, The Forsyth Institute Cambridge, MA, USA
| | - Malcolm L Snead
- Center for Craniofacial Molecular Biology, Division of Biomedical Sciences, Herman Ostrow School of Dentistry of USC, University of Southern California Los Angeles, CA, USA
| | - Toshihiro Sugiyama
- Department of Biochemistry, Akita University Graduate School of Medicine Hondo, Akita, Japan
| | - Michael L Paine
- Center for Craniofacial Molecular Biology, Division of Biomedical Sciences, Herman Ostrow School of Dentistry of USC, University of Southern California Los Angeles, CA, USA
| |
Collapse
|
30
|
Abstract
BACKGROUND N-cadherin is a cell-cell adhesion molecule and deletion of N-cadherin in mice is embryonic lethal. During the secretory stage of enamel development, E-cadherin is down-regulated and N-cadherin is specifically up-regulated in ameloblasts when groups of ameloblasts slide by one another to form the rodent decussating enamel rod pattern. Since N-cadherin promotes cell migration, we asked if N-cadherin is essential for ameloblast cell movement during enamel development. METHODOLOGY/PRINCIPAL FINDINGS The enamel organ, including its ameloblasts, is an epithelial tissue and for this study a mouse strain with N-cadherin ablated from epithelium was generated. Enamel from wild-type (WT) and N-cadherin conditional knockout (cKO) mice was analyzed. μCT and scanning electron microscopy showed that thickness, surface structure, and prism pattern of the cKO enamel looked identical to WT. No significant difference in hardness was observed between WT and cKO enamel. Interestingly, immunohistochemistry revealed the WT and N-cadherin cKO secretory stage ameloblasts expressed approximately equal amounts of total cadherins. Strikingly, E-cadherin was not normally down-regulated during the secretory stage in the cKO mice suggesting that E-cadherin can compensate for the loss of N-cadherin. Previously it was demonstrated that bone morphogenetic protein-2 (BMP2) induces E- and N-cadherin expression in human calvaria osteoblasts and we show that the N-cadherin cKO enamel organ expressed significantly more BMP2 and significantly less of the BMP antagonist Noggin than did WT enamel organ. CONCLUSIONS/SIGNIFICANCE The E- to N-cadherin switch at the secretory stage is not essential for enamel development or for forming the decussating enamel rod pattern. E-cadherin can substitute for N-cadherin during these developmental processes. Bmp2 expression may compensate for the loss of N-cadherin by inducing or maintaining E-cadherin expression when E-cadherin is normally down-regulated. Notably, this is the first demonstration of a natural endogenous increase in E-cadherin expression due to N-cadherin ablation in a healthy developing tissue.
Collapse
Affiliation(s)
- Xiaomu Guan
- Department of Mineralized Tissue Biology and Harvard School of Dental Medicine, The Forsyth Institute, Cambridge, Massachusetts, United States of America
| | - Felicitas B. Bidlack
- Department of Mineralized Tissue Biology and Harvard School of Dental Medicine, The Forsyth Institute, Cambridge, Massachusetts, United States of America
| | - Nicole Stokes
- Laboratory of Mammalian Cell Biology and Development, Howard Hughes Medical Institute, The Rockefeller University, New York, New York, United States of America
| | - John D. Bartlett
- Department of Mineralized Tissue Biology and Harvard School of Dental Medicine, The Forsyth Institute, Cambridge, Massachusetts, United States of America
- * E-mail:
| |
Collapse
|
31
|
Bartlett JD, Simmer JP. Kallikrein-related peptidase-4 (KLK4): role in enamel formation and revelations from ablated mice. Front Physiol 2014; 5:240. [PMID: 25071586 PMCID: PMC4082239 DOI: 10.3389/fphys.2014.00240] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Accepted: 06/10/2014] [Indexed: 12/26/2022] Open
Abstract
Enamel development occurs in stages. During the secretory stage, a soft protein rich enamel layer is produced that expands to reach its final thickness. During the maturation stage, proteins are removed and the enamel matures into the hardest substance in the body. KLK4 is expressed during the transition from secretory to the maturation stage and its expression continues throughout maturation. KLK4 is a glycosylated chymotrypsin-like serine protease that cleaves enamel matrix proteins prior to their export out of the hardening enamel layer. Mutations in KLK4 can cause autosomal recessive, non-syndromic enamel malformations in humans and mice. Klk4 ablated mice initially have normal-looking teeth with enamel of full thickness. However, the enamel is soft and protein-rich. Three findings are notable from Klk4 ablated mice: first, enamel rods fall from the interrod enamel leaving behind empty holes where the enamel fractures near the underlying dentin surface. Second, the ~10,000 crystallites that normally fuse to form a solid enamel rod fail to grow together in the ablated mice and can fall out of the rods. Third, and most striking, the crystallites grow substantially in width and thickness (a- and b-axis) in the ablated mice until they almost interlock. The crystallites grow in defined enamel rods, but interlocking is prevented presumably because too much protein remains. Conventional thought holds that enamel proteins bind specifically to the sides of enamel crystals to inhibit growth in width and thickness so that the thin, ribbon-like enamel crystallites grow predominantly in length. Results from Klk4 ablated mice demonstrate that this convention requires updating. An alternative mechanism is proposed whereby enamel proteins serve to form a mold or support structure that shapes and orients the mineral ribbons as they grow in length. The remnants of this support structure must be removed by KLK4 so that the crystallites can interlock to form fully hardened enamel.
Collapse
Affiliation(s)
- John D Bartlett
- Harvard School of Dental Medicine Boston, MA ; Department of Mineralized Tissue Biology, The Forsyth Institute Cambridge, MA
| | - James P Simmer
- Department of Biological and Material Sciences, University of Michigan School of Dentistry Ann Arbor, MI, USA
| |
Collapse
|
32
|
Shin M, Hu Y, Tye CE, Guan X, Deagle CC, Antone JV, Smith CE, Simmer JP, Bartlett JD. Matrix metalloproteinase-20 over-expression is detrimental to enamel development: a Mus musculus model. PLoS One 2014; 9:e86774. [PMID: 24466234 PMCID: PMC3900650 DOI: 10.1371/journal.pone.0086774] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Accepted: 12/17/2013] [Indexed: 12/25/2022] Open
Abstract
Background Matrix metalloproteinase-20 (Mmp20) ablated mice have enamel that is thin and soft with an abnormal rod pattern that abrades from the underlying dentin. We asked if introduction of transgenes expressing Mmp20 would revert this Mmp20 null phenotype back to normal. Unexpectedly, for transgenes expressing medium or high levels of Mmp20, we found opposite enamel phenotypes depending on the genetic background (Mmp20−/− or Mmp20+/+) in which the transgenes were expressed. Methodology/Principal Findings Amelx-promoter-Mmp20 transgenic founder mouse lines were assessed for transgene expression and those expressing low, medium or high levels of Mmp20 were selected for breeding into the Mmp20 null background. Regardless of expression level, each transgene brought the null enamel back to full thickness. However, the high and medium expressing Mmp20 transgenes in the Mmp20 null background had significantly harder more mineralized enamel than did the low transgene expresser. Strikingly, when the high and medium expressing Mmp20 transgenes were present in the wild-type background, the enamel was significantly less well mineralized than normal. Protein gel analysis of enamel matrix proteins from the high and medium expressing transgenes present in the wild-type background demonstrated that greater than normal amounts of cleavage products and smaller quantities of higher molecular weight proteins were present within their enamel matrices. Conclusions/Significance Mmp20 expression levels must be within a specific range for normal enamel development to occur. Creation of a normally thick enamel layer may occur over a wider range of Mmp20 expression levels, but acquisition of normal enamel hardness has a narrower range. Since over-expression of Mmp20 results in decreased enamel hardness, this suggests that a balance exists between cleaved and full-length enamel matrix proteins that are essential for formation of a properly hardened enamel layer. It also suggests that few feedback controls are present in the enamel matrix to prevent excessive MMP20 activity.
Collapse
Affiliation(s)
- Masashi Shin
- Department of Mineralized Tissue Biology and Harvard School of Dental Medicine, The Forsyth Institute, Cambridge Massachusetts, United States of America
| | - Yuanyuan Hu
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, Michigan, United States of America
| | - Coralee E. Tye
- Department of Mineralized Tissue Biology and Harvard School of Dental Medicine, The Forsyth Institute, Cambridge Massachusetts, United States of America
| | - Xiaomu Guan
- Department of Mineralized Tissue Biology and Harvard School of Dental Medicine, The Forsyth Institute, Cambridge Massachusetts, United States of America
| | - Craig C. Deagle
- Program in Endodontics, Harvard School of Dental Medicine, Boston Massachusetts, United States of America
| | - Jerry V. Antone
- Department of Mineralized Tissue Biology and Harvard School of Dental Medicine, The Forsyth Institute, Cambridge Massachusetts, United States of America
| | - Charles E. Smith
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, Michigan, United States of America
- Facility for Electron Microscopy Research, Department of Anatomy & Cell Biology, and Faculty of Dentistry, McGill University, Montreal, QC, Canada
| | - James P. Simmer
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, Michigan, United States of America
| | - John D. Bartlett
- Department of Mineralized Tissue Biology and Harvard School of Dental Medicine, The Forsyth Institute, Cambridge Massachusetts, United States of America
- * E-mail:
| |
Collapse
|
33
|
Suzuki M, Bartlett JD. Sirtuin1 and autophagy protect cells from fluoride-induced cell stress. Biochim Biophys Acta Mol Basis Dis 2013; 1842:245-55. [PMID: 24296261 DOI: 10.1016/j.bbadis.2013.11.023] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Revised: 11/12/2013] [Accepted: 11/25/2013] [Indexed: 12/11/2022]
Abstract
Sirtuin1 (SIRT1) is a nicotinamide adenine dinucleotide (NAD(+))-dependent deacetylase functioning in the regulation of metabolism, cell survival and organismal lifespan. Active SIRT1 regulates autophagy during cell stress, including calorie restriction, endoplasmic reticulum (ER) stress and oxidative stress. Previously, we reported that fluoride induces ER-stress in ameloblasts responsible for enamel formation, suggesting that ER-stress plays a role in dental fluorosis. However, the molecular mechanism of how cells respond to fluoride-induced cell stress is unclear. Here, we demonstrate that fluoride activates SIRT1 and initiates autophagy to protect cells from fluoride exposure. Fluoride treatment of ameloblast-derived cells (LS8) significantly increased Sirt1 expression and induced SIRT1 phosphorylation resulting in the augmentation of SIRT1 deacetylase activity. To demonstrate that fluoride exposure initiates autophagy, we characterized the expression of autophagy related genes (Atg); Atg5, Atg7 and Atg8/LC3 and showed that both their transcript and protein levels were significantly increased following fluoride treatment. To confirm that SIRT1 plays a protective role in fluoride toxicity, we used resveratrol (RES) to augment SIRT1 activity in fluoride treated LS8 cells. RES increased autophagy, inhibited apoptosis, and decreased fluoride cytotoxicity. Rats treated with fluoride (0, 50, 100 and 125ppm) in drinking water for 6weeks had significantly elevated expression levels of Sirt1, Atg5, Atg7 and Atg8/LC3 in their maturation stage enamel organs. Increased protein levels of p-SIRT1, ATG5 and ATG8/LC3 were present in fluoride-treated rat maturation stage ameloblasts. Therefore, the SIRT1/autophagy pathway may play a critical role as a protective response to help prevent dental fluorosis.
Collapse
Affiliation(s)
- Maiko Suzuki
- Department of Mineralized Tissue Biology, The Forsyth Institute, 245 First Street, Cambridge, MA 02142, USA; Harvard School of Dental Medicine, 188 Longwood Avenue, Boston, MA 02115, USA
| | - John D Bartlett
- Department of Mineralized Tissue Biology, The Forsyth Institute, 245 First Street, Cambridge, MA 02142, USA; Harvard School of Dental Medicine, 188 Longwood Avenue, Boston, MA 02115, USA.
| |
Collapse
|
34
|
Pugach MK, Suggs C, Li Y, Wright JT, Kulkarni AB, Bartlett JD, Gibson CW. M180 amelogenin processed by MMP20 is sufficient for decussating murine enamel. J Dent Res 2013; 92:1118-22. [PMID: 24072097 DOI: 10.1177/0022034513506444] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Amelogenin (AMELX) and matrix metalloproteinase-20 (MMP20) are essential for proper enamel development. Amelx and Mmp20 mutations cause amelogenesis imperfecta. MMP20, a protease secreted by ameloblasts, is responsible for processing enamel proteins, including AMELX, during the secretory stage of enamel formation. Of at least 16 different amelogenin splice products, the most abundant isoform found in murine ameloblasts and developing enamel is the M180 protein. To understand the role of MMP20 processing of M180 AMELX, we generated AmelxKO/Mmp20KO (DKO) mice with an amelogenin (M180Tg) transgene. We analyzed the enamel phenotype by SEM to determine enamel structure and thickness, µCT, and by nanoindentation to quantify enamel mechanical properties. M180Tg/DKO mouse enamel had 37% of the hardness of M180Tg/AmelxKO teeth and demonstrated a complete lack of normal prismatic architecture. Although molar enamel of M180Tg/AmelxKO mice was thinner than WT, it had similar mechanical properties and decussating enamel prisms, which were abolished by the loss of MMP20 in the M180Tg/DKO mice. Retention of the C-terminus or complete lack of this domain is unable to rescue amelogenin null enamel. We conclude that among amelogenins, M180 alone is sufficient for normal enamel mechanical properties and prism patterns, but that additional amelogenin splice products are required to restore enamel thickness.
Collapse
Affiliation(s)
- M K Pugach
- Department of Anatomy and Cell Biology, University of Pennsylvania School of Dental Medicine, 240 S. 40th Street, Philadelphia, PA 19104-6030, USA
| | | | | | | | | | | | | |
Collapse
|
35
|
Abstract
Matrix metalloproteinase-20 (enamelysin, MMP20) is essential for dental enamel development. Seven different MMP20 mutations in humans cause non-syndromic enamel malformations, termed amelogenesis imperfecta, and ablation of Mmp20 in mice results in thin brittle enamel with a dysplastic rod pattern. Healthy enamel formation requires the sliding movement of ameloblasts in rows during the secretory stage of development. This is essential for formation of the characteristic decussating enamel rod pattern observed in rodents, and this is also when MMP20 is secreted into the enamel matrix. Therefore, we propose that MMP20 facilitates ameloblast movement by cleaving ameloblast cell-cell contacts. Here we show that MMP20 cleaves the extracellular domains of the E- and N-cadherin adherens junction proteins, that both E- and N-cadherin transcripts are expressed at significantly higher levels in Mmp20 null vs. wild-type (WT) mice, and that in Mmp20 ablated mice, high-level ameloblast N-cadherin expression persists during the maturation stage of development. Furthermore, we show that E-cadherin gene expression is down-regulated from the pre-secretory to the secretory stage, while N-cadherin levels are up-regulated. This E- to N-cadherin switch supports epithelial migration in other tissues and may be an important event necessary for the ameloblasts to start moving in rows that slide by one another.
Collapse
Affiliation(s)
- X Guan
- Department of Mineralized Tissue Biology and Harvard School of Dental Medicine, The Forsyth Institute, 245 First Street, Cambridge, MA 02142, USA
| | | |
Collapse
|
36
|
Abstract
This review focuses on recent discoveries and delves in detail about what is known about each of the proteins (amelogenin, ameloblastin, and enamelin) and proteinases (matrix metalloproteinase-20 and kallikrein-related peptidase-4) that are secreted into the enamel matrix. After an overview of enamel development, this review focuses on these enamel proteins by describing their nomenclature, tissue expression, functions, proteinase activation, and proteinase substrate specificity. These proteins and their respective null mice and human mutations are also evaluated to shed light on the mechanisms that cause nonsyndromic enamel malformations termed amelogenesis imperfecta. Pertinent controversies are addressed. For example, do any of these proteins have a critical function in addition to their role in enamel development? Does amelogenin initiate crystallite growth, does it inhibit crystallite growth in width and thickness, or does it do neither? Detailed examination of the null mouse literature provides unmistakable clues and/or answers to these questions, and this data is thoroughly analyzed. Striking conclusions from this analysis reveal that widely held paradigms of enamel formation are inadequate. The final section of this review weaves the recent data into a plausible new mechanism by which these enamel matrix proteins support and promote enamel development.
Collapse
Affiliation(s)
- John D. Bartlett
- Harvard School of Dental Medicine & Chair, Department of Mineralized Tissue Biology, The Forsyth Institute, 245 First Street, Cambridge MA 02142, USA
| |
Collapse
|
37
|
Yamakoshi Y, Simmer JP, Bartlett JD, Karakida T, Oida S. MMP20 and KLK4 activation and inactivation interactions in vitro. Arch Oral Biol 2013; 58:1569-77. [PMID: 24112721 DOI: 10.1016/j.archoralbio.2013.08.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Revised: 07/18/2013] [Accepted: 08/05/2013] [Indexed: 10/26/2022]
Abstract
OBJECTIVE Enamelysin (MMP20) and kallikrein 4 (KLK4) are believed to be necessary to clear proteins from the enamel matrix of developing teeth. MMP20 is expressed by secretory stage ameloblasts, while KLK4 is expressed from the transition stage throughout the maturation stage. The aim of this study is to investigate the activation of KLK4 by MMP20 and the inactivation of MMP20 by KLK4. DESIGN Native pig MMP20 (pMMP20) and KLK4 (pKLK4) were isolated directly from enamel scrapings from developing molars. Recombinant human proKLK4 (rh-proKLK4) was activated by incubation with pMMP20 or recombinant human MMP20 (rhMMP20), and the resulting KLK4 activity was detected by zymography. Reaction products were isolated by reverse-phase high performance liquid chromatography (RP-HPLC), and their N-termini characterized by Edman degradation. The pMMP20 was incubated with pKLK4 under mildly acidic or under physiologic conditions, and enzyme activity was analyzed by zymography. The catalytic domain of rhMMP20 was incubated with pKLK4 or recombinant human KLK4 (rhKLK4) and the digestion products were characterized by zymography and Edman degradation. RESULTS Both pMMP20 and rhMMP20 activated rh-proKLK4 by cleaving at the propeptide-enzyme junction used in vivo. The pMMP20 was inactivated by pKLK4 under physiologic conditions, but not under mildly acidic conditions. Both pKLK4 and rhKLK4 cleaved MMP20 principally at two sites in the catalytic domain of MMP20. CONCLUSIONS MMP20 activates proKLK4 and KLK4 inactivates MMP20 in vitro, and these actions are likely to occur during enamel formation in vivo.
Collapse
Affiliation(s)
- Yasuo Yamakoshi
- Department of Biochemistry and Molecular Biology, School of Dental Medicine, Tsurumi University, 2-1-3 Tsurumi, Tsurumi-ku, Yokohama 230-8501, Japan.
| | | | | | | | | |
Collapse
|
38
|
Wang SK, Hu Y, Simmer JP, Seymen F, Estrella NMRP, Pal S, Reid BM, Yildirim M, Bayram M, Bartlett JD, Hu JCC. Novel KLK4 and MMP20 mutations discovered by whole-exome sequencing. J Dent Res 2013; 92:266-71. [PMID: 23355523 DOI: 10.1177/0022034513475626] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Non-syndromic amelogenesis imperfecta (AI) is a collection of isolated inherited enamel malformations that follow X-linked, autosomal-dominant, or autosomal-recessive patterns of inheritance. The AI phenotype is also found in syndromes. We hypothesized that whole-exome sequencing of AI probands showing simplex or recessive patterns of inheritance would identify causative mutations among the known candidate genes for AI. DNA samples obtained from 12 unrelated probands with AI were analyzed. Disease-causing mutations were identified in three of the probands: a novel single-nucleotide deletion in both KLK4 alleles (g.6930delG; c.245delG; p.Gly82Alafs*87) that shifted the reading frame, a novel missense transition mutation in both MMP20 alleles (g.15390A>G; c.611A>G; p.His204Arg) that substituted arginine for an invariant histidine known to coordinate a structural zinc ion, and a previously described nonsense transition mutation in a single allele of FAM83H (c.1379G>A; g.5663G>A; p.W460*). Erupted molars and cross-sections from unerupted parts of the mandibular incisors of Mmp20 null mice were characterized by scanning electron microscopy. Their enamel malformations closely correlated with the enamel defects displayed by the proband with the MMP20 mutation. We conclude that whole-exome sequencing is an effective means of identifying disease-causing mutations in kindreds with AI, and this technique should prove clinically useful for this purpose.
Collapse
Affiliation(s)
- S-K Wang
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, 1210 Eisenhower Place, Ann Arbor, MI 48108, USA
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
39
|
Cobley JN, Bartlett JD, Kayani A, Murray SW, Louhelainen J, Donovan T, Waldron S, Gregson W, Burniston JG, Morton JP, Close GL. PGC-1α transcriptional response and mitochondrial adaptation to acute exercise is maintained in skeletal muscle of sedentary elderly males. Biogerontology 2012. [PMID: 23187721 DOI: 10.1007/s10522-012-9408-1] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The aim of the present study was to examine the effects of ageing and training status on (1) markers of skeletal muscle mitochondrial content and (2) the ability to activate the acute signalling pathways associated with regulating exercise-induced mitochondrial biogenesis. Muscle biopsies were obtained from the vastus lateralis muscle of young untrained (24 ± 4 years, n = 6; YU), young trained (22 ± 3 years, n = 6; YT), old untrained (65 ± 6 years, n = 6; OU) and old trained (64 ± 3 years, n = 6; OT) healthy males before and after (3 h and 3 days post-exercise) completion of high-intensity interval cycling exercise. In resting muscle, lifelong training preserved mtDNA, PGC-1α and COXIV protein content such that muscles from OT individuals were comparable to muscles from both YU and YT individuals, whereas lifelong sedentary behaviour reduced such markers of mitochondrial content. Regardless of age or training status, acute exercise induced comparable increases in p38MAPK phosphorylation immediately post-exercise, PGC-1α and COXIV mRNA expression at 3 h post-exercise and COXIV protein at 3 days post-exercise. Data demonstrate that lifelong endurance training preserves skeletal muscle PGC-1α content and that despite the mitochondrial dysfunction typically observed with sedentary ageing, muscles from sedentary elderly individuals retain the capacity to activate the acute signalling pathways associated with regulating the early processes of mitochondrial biogenesis. We consider our data to have immediate translational potential as they highlight the potential therapeutic effects of exercise to induce skeletal muscle mitochondrial biogenesis persist late in adulthood, even after a lifetime of physical inactivity.
Collapse
Affiliation(s)
- J N Cobley
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Tom Reilly Building, Byrom St Campus, Liverpool L3 3AF, UK
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
40
|
Abstract
The ameloblast cell layer of the enamel organ is in contact with the forming enamel as it develops into the hardest substance in the body. Ameloblasts move in groups that slide by one another as the enamel layer thickens. Each ameloblast is responsible for the formation of one enamel rod, and the rods are the mineralized trail that moving ameloblasts leave behind. Matrix metalloproteinases (MMPs) facilitate cell movement in various tissues during development, and in this review we suggest that the tooth-specific MMP, enamelysin (MMP20), facilitates ameloblast movements during enamel development. Mmp20 null mice have thin brittle enamel with disrupted rod patterns that easily abrades from the underlying dentin. Strikingly, the Mmp20 null mouse enamel organ morphology is noticeably dysplastic during late-stage development, when MMP20 is no longer expressed. We suggest that in addition to its role of cleaving enamel matrix proteins, MMP20 also cleaves junctional complexes present on ameloblasts to foster the cell movement necessary for formation of the decussating enamel rod pattern. Therefore, inactivation of MMP20 would result in tight ameloblast cell-cell attachments that may cause maturation-stage enamel organ dysplasia. The tight ameloblast attachments would also preclude the ameloblast movement necessary to form decussating enamel rod patterns.
Collapse
Affiliation(s)
- J D Bartlett
- Department of Mineralized Tissue Biology, Forsyth Institute, Harvard School of Dental Medicine, Cambridge, MA, USA.
| | | |
Collapse
|
41
|
Smith CE, Hu Y, Richardson AS, Bartlett JD, Hu JCC, Simmer JP. Relationships between protein and mineral during enamel development in normal and genetically altered mice. Eur J Oral Sci 2012; 119 Suppl 1:125-35. [PMID: 22243238 DOI: 10.1111/j.1600-0722.2011.00871.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The purpose of this study was to quantify and compare the amounts of volatiles (mostly protein) and mineral present in developing incisor enamel in normal mice and in those genetically engineered for absence of intact enamelin, ameloblastin, matrix metalloproteinase 20 (MMP20) or kallikrein-related peptidase 4 (KLK4). Data indicated that all mice showed peaks in the gross weight of volatiles and a similar weight of mineral at locations on incisors normally associated with early maturation. Thereafter, the content of volatiles on normal incisors declined rapidly by as much as 62%, but not by 100%, over 2 mm, accompanied by increases of ≈ threefold in mineral weights. Enamelin heterozygous mice (lower incisors) showed a decrease in volatile content across the maturation stage, yet mineral failed to increase significantly. Mmp20 null mice showed no significant loss of volatiles from maturing enamel, yet the amount of mineral increased. Klk4 null mice showed normal mineral acquisition up to early maturation, but the input of new volatiles in mid to late maturation caused the final mineralization to slow below normal levels. These results suggest that it is not only the amount of protein but also the nature or type of protein or fragments present in the local crystallite environment that affects their volumetric expansion as they mature.
Collapse
Affiliation(s)
- Charles E Smith
- Facility for Electron Microscopy Research, Department of Anatomy & Cell Biology, and Faculty of Dentistry, McGill University, Montreal, QC, Canada.
| | | | | | | | | | | |
Collapse
|
42
|
Yamakoshi Y, Richardson AS, Nunez SM, Yamakoshi F, Milkovich RN, Hu JCC, Bartlett JD, Simmer JP. Enamel proteins and proteases in Mmp20 and Klk4 null and double-null mice. Eur J Oral Sci 2012; 119 Suppl 1:206-16. [PMID: 22243248 DOI: 10.1111/j.1600-0722.2011.00866.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Matrix metalloproteinase 20 (MMP20) and kallikrein-related peptidase 4 (KLK4) are thought to be necessary to clear proteins from the enamel matrix of developing teeth. We characterized Mmp20 and Klk4 null mice to better understand their roles in matrix degradation and removal. Histological examination showed retained organic matrix in Mmp20, Klk4, and Mmp20/Klk4 double-null mouse enamel matrix, but not in the wild-type. X-gal histostaining of Mmp20 null mice heterozygous for the Klk4 knockout/lacZ knockin showed that Klk4 is expressed normally in the Mmp20 null background. This finding was corroborated by zymogram and western blotting, which discovered a 40-kDa protease induced in the maturation stage of Mmp20 null mice. Proteins were extracted from secretory-stage or maturation-stage maxillary first molars from wild-type, Mmp20 null, Klk4 null, and Mmp20/Klk4 double-null mice and were analyzed by SDS-PAGE and western blotting. Only intact amelogenins and ameloblastin were observed in secretory-stage enamel of Mmp20 null mice, whereas the secretory-stage matrix from Klk4 null mice was identical to the matrix from wild-type mice. More residual matrix was observed in the double-null mice compared with either of the single-null mice. These results support the importance of MMP20 during the secretory stage and of KLK4 during the maturation stage and show there is only limited functional redundancy for these enzymes.
Collapse
Affiliation(s)
- Yasuo Yamakoshi
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, MI 48108, USA
| | | | | | | | | | | | | | | |
Collapse
|
43
|
Bartlett JD, Skobe Z, Nanci A, Smith CE. Matrix metalloproteinase 20 promotes a smooth enamel surface, a strong dentino-enamel junction, and a decussating enamel rod pattern. Eur J Oral Sci 2012; 119 Suppl 1:199-205. [PMID: 22243247 DOI: 10.1111/j.1600-0722.2011.00864.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Mutations of the matrix metalloproteinase 20 (MMP20, enamelysin) gene cause autosomal-recessive amelogenesis imperfecta, and Mmp20 ablated mice also have malformed dental enamel. Here we showed that Mmp20 null mouse secretory-stage ameloblasts maintain a columnar shape and are present as a single layer of cells. However, the maturation-stage ameloblasts from null mouse cover extraneous nodules of ectopic calcified material formed at the enamel surface. Remarkably, nodule formation occurs in null mouse enamel when MMP20 is normally no longer expressed. The malformed enamel in Mmp20 null teeth was loosely attached to the dentin and the entire enamel layer tended to separate from the dentin, indicative of a faulty dentino-enamel junction (DEJ). The enamel rod pattern was also altered in Mmp20 null mice. Each enamel rod is formed by a single ameloblast and is a mineralized record of the migration path of the ameloblast that formed it. The enamel rods in Mmp20 null mice were grossly malformed or absent, indicating that the ameloblasts do not migrate properly when backing away from the DEJ. Thus, MMP20 is required for ameloblast cell movement necessary to form the decussating enamel rod patterns, for the prevention of ectopic mineral formation, and to maintain a functional DEJ.
Collapse
Affiliation(s)
- John D Bartlett
- Department of Cytokine Biology, Forsyth Institute, Cambridge, MA 02142, USA.
| | | | | | | |
Collapse
|
44
|
Hu Y, Hu JCC, Smith CE, Bartlett JD, Simmer JP. Kallikrein-related peptidase 4, matrix metalloproteinase 20, and the maturation of murine and porcine enamel. Eur J Oral Sci 2012; 119 Suppl 1:217-25. [PMID: 22243249 DOI: 10.1111/j.1600-0722.2011.00859.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The crowns of matrix metalloproteinase 20 (Mmp20) null mice fracture at the dentino-enamel junction (DEJ), whereas the crowns of kallikrein-related peptidase 4 (Klk4) null mice fracture in the deep enamel just above the DEJ. We used backscatter scanning electron microscopy to assess enamel mineralization in incisors from 9-wk-old wild-type, Klk4 null, and Mmp20 null mice, and in developing pig molars. We observed a line of hypermineralization along the DEJ in developing wild-type mouse and pig teeth. This line was discernible from the early secretory stage until the enamel in the maturation stage reached a similar density. The line was apparent in Klk4 null mice, but absent in Mmp20 null mice. Enamel in the Klk4 null mice matured normally at the surface, but was progressively less mineralized with depth. Enamel in the Mmp20 null mice formed as a mineral bilayer, with neither layer looking like true enamel. The most superficial mineral layer expanded during the maturation stage and formed irregular surface nodules. A surprising finding was the observation of electron backscatter from mid-maturation wild-type ameloblasts, which we attributed to the accumulation and release of iron. We conclude that enamel breaks in the deep enamel of Klk4 null mice because of decreasing enamel maturation with depth, and at the DEJ in Mmp20 null mice because of hypomineralization at the DEJ.
Collapse
Affiliation(s)
- Yuanyuan Hu
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, MI 48108, USA
| | | | | | | | | |
Collapse
|
45
|
Poché RA, Sharma R, Garcia MD, Wada AM, Nolte MJ, Udan RS, Paik JH, DePinho RA, Bartlett JD, Dickinson ME. Transcription factor FoxO1 is essential for enamel biomineralization. PLoS One 2012; 7:e30357. [PMID: 22291941 PMCID: PMC3265481 DOI: 10.1371/journal.pone.0030357] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Accepted: 12/14/2011] [Indexed: 01/10/2023] Open
Abstract
The Transforming growth factor β (Tgf-β) pathway, by signaling via the activation of Smad transcription factors, induces the expression of many diverse downstream target genes thereby regulating a vast array of cellular events essential for proper development and homeostasis. In order for a specific cell type to properly interpret the Tgf-β signal and elicit a specific cellular response, cell-specific transcriptional co-factors often cooperate with the Smads to activate a discrete set of genes in the appropriate temporal and spatial manner. Here, via a conditional knockout approach, we show that mice mutant for Forkhead Box O transcription factor FoxO1 exhibit an enamel hypomaturation defect which phenocopies that of the Smad3 mutant mice. Furthermore, we determined that both the FoxO1 and Smad3 mutant teeth exhibit changes in the expression of similar cohort of genes encoding enamel matrix proteins required for proper enamel development. These data raise the possibility that FoxO1 and Smad3 act in concert to regulate a common repertoire of genes necessary for complete enamel maturation. This study is the first to define an essential role for the FoxO family of transcription factors in tooth development and provides a new molecular entry point which will allow researchers to delineate novel genetic pathways regulating the process of biomineralization which may also have significance for studies of human tooth diseases such as amelogenesis imperfecta.
Collapse
Affiliation(s)
- Ross A. Poché
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Ramaswamy Sharma
- Department of Cytokine Biology, Forsyth Institute, and Department of Developmental Biology, Harvard School of Dental Medicine, Cambridge, Massachusetts, United States of America
| | - Monica D. Garcia
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Aya M. Wada
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Mark J. Nolte
- Department of Genetics, University of Texas M. D. Anderson Cancer Center, Houston, Texas, United States of America
| | - Ryan S. Udan
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Ji-Hye Paik
- Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, New York, New York, United States of America
| | - Ronald A. DePinho
- Departments of Medical Oncology, Medicine, and Genetics, Belfer Institute for Applied Cancer Science, Dana-Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts, United States of America
| | - John D. Bartlett
- Department of Cytokine Biology, Forsyth Institute, and Department of Developmental Biology, Harvard School of Dental Medicine, Cambridge, Massachusetts, United States of America
| | - Mary E. Dickinson
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas, United States of America
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, United States of America
- * E-mail:
| |
Collapse
|
46
|
Pugach MK, Ozer F, Li Y, Sheth K, Beasley R, Resnick A, Daneshmehr L, Kulkarni AB, Bartlett JD, Gibson CW, Lindemeyer RG. The use of mouse models to investigate shear bond strength in amelogenesis imperfecta. J Dent Res 2011; 90:1352-7. [PMID: 21917602 DOI: 10.1177/0022034511421929] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Patients with amelogenesis imperfecta (AI) have defective enamel; therefore, bonded restorations of patients with AI have variable success rates. To distinguish which cases of AI may have good clinical outcomes with bonded materials, we evaluated etching characteristics and bond strength of enamel in mouse models, comparing wild-type (WT) with those having mutations in amelogenin (Amelx) and matrix metalloproteinase-20 (Mmp20), which mimic 2 forms of human AI. Etched enamel surfaces were compared for roughness by scanning electron microscopy (SEM) images. Bonding was compared through shear bond strength (SBS) studies with 2 different systems (etch-and-rinse and self-etch). Etched enamel surfaces of incisors from Amelx knock-out (AmelxKO) mice appeared randomly organized and non-uniform compared with WT. Etching of Mmp20KO surfaces left little enamel, and the etching pattern was indistinguishable from unetched surfaces. SBS results were significantly different when AmelxKO and Mmp20KO enamel surfaces were compared. A significant increase in SBS was measured for all samples when the self-etch system was compared with the etch-and-rinse system. We have developed a novel system for testing shear bond strength of mouse incisors with AI variants, and analysis of these data may have important clinical implications for the treatment of patients with AI.
Collapse
Affiliation(s)
- M K Pugach
- Department of Anatomy and Cell Biology University of Pennsylvania School of Dental Medicine, Philadelphia, PA 19104, USA
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
47
|
Abstract
BACKGROUND The enamel layerof kallikrein 4 (Klk4)-null mice has a normal thickness and a decussating pattern of enamel rods, but it contains residual enamel proteins, is less highly mineralized, and fractures in its deepest part just above the dentino-enamel junction (DEJ). The plane of fracture is puzzling because the deepest enamel is deposited earliest and, through the action of the secretory stage enamel protease (Mmp20), is the most mature part of the enamel layer at the time of the onset of Klk4 expression. OBJECTIVES To characterize the planes of fracture in Mmp20- and Klk4-null mice and to localize Klk4 expression in developing teeth. METHODS Klk4- and Mmp20-null mice were sacrificed at 7 weeks and their mandibular incisors were characterized by scanning electron microscopy. Klk4(+/)(lac)(Z) mice were mated with Klk4(+/)(lac)(Z) mice. Offspring were genotyped by polymerase chain reaction. Klk4(+/)(+), Klk4(+/)(lac)(Z), and Klk4(lac)(Z/)(lac)(Z) (null) littermates on postnatal days 5, 8, 11, and 14 were processed for β-galactosidase histochemistry. RESULTS The enamel layer fractures at the DEJ in Mmp20-null mice, and fractures occur in enamel above the DEJ in Klk4-null mice. Klk4 is not expressed by secretory-stage ameloblasts, murine odontoblasts beneath the secretory stage, or maturation-stage ameloblasts. Klk4 is specifically expressed by transition and maturation-stage ameloblasts. CONCLUSIONS The breakage of enamel near the DEJ in Klk4-null mice is not due to a failure of odontoblasts to express Klk4, but it relates to a progressive hypomineralization of enamel with depth.
Collapse
Affiliation(s)
- James P. Simmer
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, Mich
| | - Yuanyuan Hu
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, Mich
| | - Amelia S. Richardson
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, Mich
| | - John D. Bartlett
- Department of Cytokine Biology, The Forsyth Institute, Cambridge, Mass., USA
| | - Jan C.-C. Hu
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, Mich
| |
Collapse
|
48
|
Bartlett JD, Yamakoshi Y, Simmer JP, Nanci A, Smith CE. MMP20 cleaves E-cadherin and influences ameloblast development. Cells Tissues Organs 2011; 194:222-6. [PMID: 21525715 DOI: 10.1159/000324205] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Dental enamel development occurs in stages as observed by the changing morphology of the ameloblasts that are responsible for enamel formation. During the secretory stage of development, proteins including MMP20 are secreted into the enamel matrix. MMP20 is required for proper enamel formation as mutation of the Mmp20 gene causes autosomal recessive amelogenesis imperfecta. Here, we examined in detail the morphology of the Mmp20-null ameloblast cell layer. Intriguingly, we found that the Mmp20-null mouse secretory stage ameloblasts retract their Tomes' processes as if preparing to enter the maturation stage but later reextend their Tomes' processes as if resuming the secretory stage. We also demonstrated that MMP20 cleaves epithelial cadherin, i.e. E-cadherin. Cadherins are transmembrane proteins with extracellular domains that provide adhesive contacts between neighboring cells. Their intracellular domains bind to the cell cytoskeleton through catenins, including β-catenin. When specific MMPs cleave the cadherin extracellular domain, β-catenin is released and may locate to the cell nucleus as a transcription factor. Therefore, MMP20 may influence ameloblast developmental progression through hydrolysis of cadherin extracellular domains with associated release of transcription factor(s).
Collapse
Affiliation(s)
- John D Bartlett
- Department of Cytokine Biology, Forsyth Institute and Department of Developmental Biology, Harvard School of Dental Medicine, Cambridge, Mass., USA.
| | | | | | | | | |
Collapse
|
49
|
Smith CE, Richardson AS, Hu Y, Bartlett JD, Hu JCC, Simmer JP. Effect of kallikrein 4 loss on enamel mineralization: comparison with mice lacking matrix metalloproteinase 20. J Biol Chem 2011; 286:18149-60. [PMID: 21454549 DOI: 10.1074/jbc.m110.194258] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Enamel formation depends on a triad of tissue-specific matrix proteins (amelogenin, ameloblastin, and enamelin) to help initiate and stabilize progressively elongating, thin mineral ribbons of hydroxyapatite formed during an appositional growth phase. Subsequently, these proteins are eradicated to facilitate lateral expansion of the hydroxyapatite crystallites. The purpose of this study was to investigate changes in enamel mineralization occurring in mice unable to produce kallikrein 4 (Klk4), a proteinase associated with terminal extracellular degradation of matrix proteins during the maturation stage. Mice lacking functional matrix metalloproteinase 20 (Mmp20), a proteinase associated with early cleavage of matrix proteins during the secretory stage, were also analyzed as a frame of reference. The results indicated that mice lacking Klk4 produce enamel that is normal in thickness and overall organization in terms of layers and rod/inter-rod structure, but there is a developmental defect in enamel rods where they first form near the dentinoenamel junction. Mineralization is normal up to early maturation after which the enamel both retains and gains additional proteins and is unable to mature beyond 85% mineral by weight. The outmost enamel is hard, but inner regions are soft and contain much more protein than normal. The rate of mineral acquisition overall is lower by 25%. Mice lacking functional Mmp20 produce enamel that is thin and structurally abnormal. Relatively high amounts of protein remain throughout maturation, but the enamel is able to change from 67 to 75% mineral by weight during maturation. These findings reaffirm the importance of secreted proteinases to enamel mineral acquisition.
Collapse
Affiliation(s)
- Charles E Smith
- Facility for Electron Microscopy Research, Department of Anatomy and Cell Biology and Faculty of Dentistry, McGill University, Montreal, Quebec H3A 2B2, Canada.
| | | | | | | | | | | |
Collapse
|
50
|
Franco GCN, Kajiya M, Nakanishi T, Ohta K, Rosalen PL, Groppo FC, Ernst CWO, Boyesen JL, Bartlett JD, Stashenko P, Taubman MA, Kawai T. Inhibition of matrix metalloproteinase-9 activity by doxycycline ameliorates RANK ligand-induced osteoclast differentiation in vitro and in vivo. Exp Cell Res 2011; 317:1454-64. [PMID: 21420951 DOI: 10.1016/j.yexcr.2011.03.014] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2010] [Revised: 03/13/2011] [Accepted: 03/15/2011] [Indexed: 11/17/2022]
Abstract
Tetracycline antibiotics, including doxycycli\e (DOX), have been used to treat bone resorptive diseases, partially because of their activity to suppress osteoclastogenesis induced by receptor activator of nuclear factor kappa B ligand (RANKL). However, their precise inhibitory mechanism remains unclear. Therefore, the present study examined the effect of Dox on osteoclastogenesis signaling induced by RANKL, both in vitro and in vivo. Although Dox inhibited RANKL-induced osteoclastogenesis and down-modulated the mRNA expression of functional osteoclast markers, including tartrate-resistant acid phosphatase (TRAP) and cathepsin K, Dox neither affected RANKL-induced MAPKs phosphorylation nor NFATc1 gene expression in RAW264.7 murine monocytic cells. Gelatin zymography and Western blot analyses showed that Dox down-regulated the enzyme activity of RANKL-induced MMP-9, but without affecting its protein expression. Furthermore, MMP-9 enzyme inhibitor also attenuated both RANKL-induced osteoclastogenesis and up-regulation of TRAP and cathepsin K mRNA expression, indicating that MMP-9 enzyme action is engaged in the promotion of RANKL-induced osteoclastogenesis. Finally, Dox treatment abrogated RANKL-induced osteoclastogenesis and TRAP activity in mouse calvaria along with the suppression of MMP9 enzyme activity, again without affecting the expression of MMP9 protein. These findings suggested that Dox inhibits RANKL-induced osteoclastogenesis by its inhibitory effect on MMP-9 enzyme activity independent of the MAPK-NFATc1 signaling cascade.
Collapse
Affiliation(s)
- Gilson C N Franco
- Department of Immunology, Forsyth Institute, Cambridge, MA 02142, USA
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|