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Dong J, Ruan W, Duan X. Molecular-based phenotype variations in amelogenesis imperfecta. Oral Dis 2023; 29:2334-2365. [PMID: 37154292 DOI: 10.1111/odi.14599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 04/03/2023] [Accepted: 04/15/2023] [Indexed: 05/10/2023]
Abstract
Amelogenesis imperfecta (AI) is one of the typical dental genetic diseases in human. It can occur isolatedly or as part of a syndrome. Previous reports have mainly clarified the types and mechanisms of nonsyndromic AI. This review aimed to compare the phenotypic differences among the hereditary enamel defects with or without syndromes and their underlying pathogenic genes. We searched the articles in PubMed with different strategies or keywords including but not limited to amelogenesis imperfecta, enamel defects, hypoplastic/hypomaturation/hypocalcified, syndrome, or specific syndrome name. The articles with detailed clinical information about the enamel and other phenotypes and clear genetic background were used for the analysis. We totally summarized and compared enamel phenotypes of 18 nonsyndromic AI with 17 causative genes and 19 syndromic AI with 26 causative genes. According to the clinical features, radiographic or ultrastructural changes in enamel, the enamel defects were basically divided into hypoplastic and hypomineralized (hypomaturated and hypocalcified) and presented a higher heterogeneity which were closely related to the involved pathogenic genes, types of mutation, hereditary pattern, X chromosome inactivation, incomplete penetrance, and other mechanisms.The gene-specific enamel phenotypes could be an important indicator for diagnosing nonsyndromic and syndromic AI.
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Affiliation(s)
- Jing Dong
- State Key Laboratory of Military Stomatology, Shaanxi Key Laboratory of Stomatology, Department of Oral Biology & Clinic of Oral Rare Diseases and Genetic Diseases, School of Stomatology, National Clinical Research Center for Oral Disease, The Fourth Military Medical University, Xi'an, China
- College of Life Sciences, Northwest University, Xi'an, China
| | - Wenyan Ruan
- State Key Laboratory of Military Stomatology, Shaanxi Key Laboratory of Stomatology, Department of Oral Biology & Clinic of Oral Rare Diseases and Genetic Diseases, School of Stomatology, National Clinical Research Center for Oral Disease, The Fourth Military Medical University, Xi'an, China
| | - Xiaohong Duan
- State Key Laboratory of Military Stomatology, Shaanxi Key Laboratory of Stomatology, Department of Oral Biology & Clinic of Oral Rare Diseases and Genetic Diseases, School of Stomatology, National Clinical Research Center for Oral Disease, The Fourth Military Medical University, Xi'an, China
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2
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Kim YJ, Zhang H, Lee Y, Seymen F, Koruyucu M, Kasimoglu Y, Simmer JP, Hu JCC, Kim JW. Novel WDR72 Mutations Causing Hypomaturation Amelogenesis Imperfecta. J Pers Med 2023; 13:326. [PMID: 36836560 PMCID: PMC9965932 DOI: 10.3390/jpm13020326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2023] [Revised: 02/10/2023] [Accepted: 02/11/2023] [Indexed: 02/16/2023] Open
Abstract
Amelogenesis imperfecta (AI) is a heterogeneous collection of hereditary enamel defects. The affected enamel can be classified as hypoplastic, hypomaturation, or hypocalcified in form. A better understanding of normal amelogenesis and improvements in our ability to diagnose AI through genetic testing can be realized through more complete knowledge of the genes and disease-causing variants that cause AI. In this study, mutational analysis was performed with whole exome sequencing (WES) to identify genetic etiology underlying the hypomaturation AI condition in affected families. Mutational analyses identified biallelic WDR72 mutations in four hypomaturation AI families. Novel mutations include a homozygous deletion and insertion mutation (NM_182758.4: c.2680_2699delinsACTATAGTT, p.(Ser894Thrfs*15)), compound heterozygous mutations (paternal c.2332dupA, p.(Met778Asnfs*4)) and (maternal c.1287_1289del, p.(Ile430del)) and a homozygous 3694 bp deletion that includes exon 14 (NG_017034.2:g.96472_100165del). A homozygous recurrent mutation variant (c.1467_1468delAT, p.(Val491Aspfs*8)) was also identified. Current ideas on WDR72 structure and function are discussed. These cases expand the mutational spectrum of WDR72 mutations causing hypomaturation AI and improve the possibility of genetic testing to accurately diagnose AI caused by WDR72 defects.
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Affiliation(s)
- Youn Jung Kim
- Department of Pediatric Dentistry & DRI, School of Dentistry, Seoul National University, Seoul 03080, Republic of Korea
| | - Hong Zhang
- Department of Biologic and Materials Sciences & Prosthodontics, School of Dentistry, University of Michigan, Ann Arbor, MI 48109, USA
| | - Yejin Lee
- Department of Pediatric Dentistry & DRI, School of Dentistry, Seoul National University, Seoul 03080, Republic of Korea
| | - Figen Seymen
- Department of Paediatric Dentistry, Faculty of Dentistry, Altinbas University, Istanbul 34147, Turkey
| | - Mine Koruyucu
- Department of Pedodontics, Faculty of Dentistry, Istanbul University, Istanbul 34116, Turkey
| | - Yelda Kasimoglu
- Department of Pedodontics, Faculty of Dentistry, Istanbul University, Istanbul 34116, Turkey
| | - James P. Simmer
- Department of Biologic and Materials Sciences & Prosthodontics, School of Dentistry, University of Michigan, Ann Arbor, MI 48109, USA
| | - Jan C.-C. Hu
- Department of Biologic and Materials Sciences & Prosthodontics, School of Dentistry, University of Michigan, Ann Arbor, MI 48109, USA
| | - Jung-Wook Kim
- Department of Pediatric Dentistry & DRI, School of Dentistry, Seoul National University, Seoul 03080, Republic of Korea
- Department of Molecular Genetics & DRI, School of Dentistry, Seoul National University, Seoul 03080, Republic of Korea
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3
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Liu X, Xu C, Tian Y, Sun Y, Zhang J, Bai J, Pan Z, Feng W, Xu M, Li C, Li J, Gao Y. RUNX2 contributes to TGF-β1-induced expression of Wdr72 in ameloblasts during enamel mineralization. Biomed Pharmacother 2019; 118:109235. [DOI: 10.1016/j.biopha.2019.109235] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 07/13/2019] [Accepted: 07/16/2019] [Indexed: 01/26/2023] Open
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Zhang H, Koruyucu M, Seymen F, Kasimoglu Y, Kim JW, Tinawi S, Zhang C, Jacquemont M, Vieira A, Simmer J, Hu J. WDR72 Mutations Associated with Amelogenesis Imperfecta and Acidosis. J Dent Res 2019; 98:541-548. [PMID: 30779877 PMCID: PMC6481005 DOI: 10.1177/0022034518824571] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Dental enamel malformations, or amelogenesis imperfecta (AI), can be isolated or syndromic. To improve the prospects of making a successful diagnosis by genetic testing, it is important that the full range of genes and mutations that cause AI be determined. Defects in WDR72 (WD repeat-containing protein 72; OMIM *613214) cause AI, type IIA3 (OMIM #613211), which follows an autosomal recessive pattern of inheritance. The defective enamel is normal in thickness, severely hypomineralized, orange-brown stained, and susceptible to attrition. We identified 6 families with biallelic WDR72 mutations by whole exome sequence analyses that perfectly segregated with the enamel phenotype. The novel mutations included 3 stop-gains [NM_182758.2: c.377G>A/p.(Trp126*), c.1801C>T/p.(Arg601*), c.2350A>T/p.(Arg784*)], a missense mutation [c.1265G>T/p.(Gly422Val)], and a 62,138-base pair deletion (NG_017034.2: g.35441_97578del62138) that removed WDR72 coding exons 3 through 13. A previously reported WDR72 frameshift was also observed [c.1467_1468delAT/p.(Val491Aspfs*8)]. Three of the affected patients showed decreased serum pH, consistent with a diagnosis of renal tubular acidosis. Percentiles of stature and body weight varied among 8 affected individuals but did not show a consistent trend. These studies support that WDR72 mutations cause a syndromic form of AI and improve our ability to diagnose AI caused by WDR72 defects.
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Affiliation(s)
- H. Zhang
- Department of Biologic and Materials Sciences, School of Dentistry, University of Michigan, Ann Arbor, MI, USA
| | - M. Koruyucu
- Department of Pedodontics, Faculty of Dentistry, Istanbul University, Istanbul, Turkey
| | - F. Seymen
- Department of Pedodontics, Faculty of Dentistry, Istanbul University, Istanbul, Turkey
| | - Y. Kasimoglu
- Department of Pedodontics, Faculty of Dentistry, Istanbul University, Istanbul, Turkey
| | - J.-W. Kim
- Department of Molecular Genetics and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Republic of Korea
- Department of Pediatric Dentistry and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Republic of Korea
| | - S. Tinawi
- Department of Biologic and Materials Sciences, School of Dentistry, University of Michigan, Ann Arbor, MI, USA
| | - C. Zhang
- Department of Biologic and Materials Sciences, School of Dentistry, University of Michigan, Ann Arbor, MI, USA
| | - M.L. Jacquemont
- Génétique Médicale, Pôle femme-mère-enfant, CHU la Réunion site GHSR, BP 350-97448 Saint Pierre Cedex
| | - A.R. Vieira
- Departments of Oral Biology and Pediatric Dentistry, Center for Craniofacial and Dental Genetics, School of Dental Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Human Genetics, Graduate School of Public Health; Clinical and Translational Science Institute, University of Pittsburgh, Pittsburgh, PA, USA
| | - J.P. Simmer
- Department of Biologic and Materials Sciences, School of Dentistry, University of Michigan, Ann Arbor, MI, USA
| | - J.C.C. Hu
- Department of Biologic and Materials Sciences, School of Dentistry, University of Michigan, Ann Arbor, MI, USA
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5
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Rungroj N, Nettuwakul C, Sawasdee N, Sangnual S, Deejai N, Misgar RA, Pasena A, Khositseth S, Kirdpon S, Sritippayawan S, Vasuvattakul S, Yenchitsomanus PT. Distal renal tubular acidosis caused by tryptophan-aspartate repeat domain 72 (WDR72) mutations. Clin Genet 2018; 94:409-418. [PMID: 30028003 DOI: 10.1111/cge.13418] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Revised: 06/21/2018] [Accepted: 07/17/2018] [Indexed: 12/18/2022]
Abstract
Hereditary distal renal tubular acidosis (dRTA) is a rare genetic disease that is caused by mutations in SLC4A1, ATP6V1B1, or ATP6V0A4. However, there are many families with hereditary dRTA in whom the disease-causing genes are unknown. Accordingly, we performed whole exome sequencing and genetic studies of the members of a family with autosomal recessive dRTA of an unknown genetic etiology. Here, we report compound heterozygous pathogenic variations in tryptophan-aspartate repeat domain 72 (WDR72) (c.1777A>G [p.R593G] and c.2522T>A [p.L841Q]) in three affected siblings of a family with dRTA. Both variants segregated with dRTA in the family and were not observed in normal control subjects. Homologous modeling and in silico mutagenesis indicated that R593G and L841Q alter the H-bond formations in the nearby residues, affecting the WDR72 protein structure. All these evidences indicate that the identified WDR72 variations were probably to have caused hereditary dRTA in the reported family. In addition, homozygous nonsense mutation (c.2686C>T [p.R896X]) was identified in another family, strongly supporting the causal role of WDR72 in dRTA. Based on our literature review, WDR72 mutations associated with dRTA have not been previously described. This is the first identification of pathogenic variations in WDR72 as a cause of hereditary dRTA.
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Affiliation(s)
- N Rungroj
- Division of Molecular Medicine, Department of Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.,Division of Molecular Genetics, Department of Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - C Nettuwakul
- Division of Molecular Medicine, Department of Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - N Sawasdee
- Division of Molecular Medicine, Department of Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - S Sangnual
- Division of Molecular Medicine, Department of Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - N Deejai
- Division of Molecular Medicine, Department of Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - R A Misgar
- Department of Endocrinology, Sher-i-Kashmir Institute of Medical Sciences, Srinagar, India
| | - A Pasena
- Division of Molecular Medicine, Department of Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.,Department of Immunology and Immunology Graduate Program, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - S Khositseth
- Department of Pediatrics, Faculty of Medicine, Thammasat University, Pathumthani, Thailand
| | - S Kirdpon
- Department of Pediatrics, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
| | - S Sritippayawan
- Division of Nephrology, Department of Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - S Vasuvattakul
- Division of Nephrology, Department of Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - P T Yenchitsomanus
- Division of Molecular Medicine, Department of Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
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Smith CEL, Poulter JA, Antanaviciute A, Kirkham J, Brookes SJ, Inglehearn CF, Mighell AJ. Amelogenesis Imperfecta; Genes, Proteins, and Pathways. Front Physiol 2017; 8:435. [PMID: 28694781 PMCID: PMC5483479 DOI: 10.3389/fphys.2017.00435] [Citation(s) in RCA: 143] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Accepted: 06/08/2017] [Indexed: 01/11/2023] Open
Abstract
Amelogenesis imperfecta (AI) is the name given to a heterogeneous group of conditions characterized by inherited developmental enamel defects. AI enamel is abnormally thin, soft, fragile, pitted and/or badly discolored, with poor function and aesthetics, causing patients problems such as early tooth loss, severe embarrassment, eating difficulties, and pain. It was first described separately from diseases of dentine nearly 80 years ago, but the underlying genetic and mechanistic basis of the condition is only now coming to light. Mutations in the gene AMELX, encoding an extracellular matrix protein secreted by ameloblasts during enamel formation, were first identified as a cause of AI in 1991. Since then, mutations in at least eighteen genes have been shown to cause AI presenting in isolation of other health problems, with many more implicated in syndromic AI. Some of the encoded proteins have well documented roles in amelogenesis, acting as enamel matrix proteins or the proteases that degrade them, cell adhesion molecules or regulators of calcium homeostasis. However, for others, function is less clear and further research is needed to understand the pathways and processes essential for the development of healthy enamel. Here, we review the genes and mutations underlying AI presenting in isolation of other health problems, the proteins they encode and knowledge of their roles in amelogenesis, combining evidence from human phenotypes, inheritance patterns, mouse models, and in vitro studies. An LOVD resource (http://dna2.leeds.ac.uk/LOVD/) containing all published gene mutations for AI presenting in isolation of other health problems is described. We use this resource to identify trends in the genes and mutations reported to cause AI in the 270 families for which molecular diagnoses have been reported by 23rd May 2017. Finally we discuss the potential value of the translation of AI genetics to clinical care with improved patient pathways and speculate on the possibility of novel treatments and prevention strategies for AI.
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Affiliation(s)
- Claire E L Smith
- Division of Oral Biology, School of Dentistry, St. James's University Hospital, University of LeedsLeeds, United Kingdom.,Section of Ophthalmology and Neuroscience, St. James's University Hospital, University of LeedsLeeds, United Kingdom
| | - James A Poulter
- Section of Ophthalmology and Neuroscience, St. James's University Hospital, University of LeedsLeeds, United Kingdom
| | - Agne Antanaviciute
- Section of Genetics, School of Medicine, St. James's University Hospital, University of LeedsLeeds, United Kingdom
| | - Jennifer Kirkham
- Division of Oral Biology, School of Dentistry, St. James's University Hospital, University of LeedsLeeds, United Kingdom
| | - Steven J Brookes
- Division of Oral Biology, School of Dentistry, St. James's University Hospital, University of LeedsLeeds, United Kingdom
| | - Chris F Inglehearn
- Section of Ophthalmology and Neuroscience, St. James's University Hospital, University of LeedsLeeds, United Kingdom
| | - Alan J Mighell
- Section of Ophthalmology and Neuroscience, St. James's University Hospital, University of LeedsLeeds, United Kingdom.,Oral Medicine, School of Dentistry, University of LeedsLeeds, United Kingdom
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Hentschel J, Tatun D, Parkhomchuk D, Kurth I, Schimmel B, Heinrich-Weltzien R, Bertzbach S, Peters H, Beetz C. Identification of the first multi-exonic WDR72 deletion in isolated amelogenesis imperfecta, and generation of a WDR72-specific copy number screening tool. Gene 2016; 590:1-4. [PMID: 27259663 DOI: 10.1016/j.gene.2016.05.040] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 05/29/2016] [Indexed: 01/18/2023]
Abstract
Amelogenesis imperfecta (AI) is a clinically and genetically heterogeneous disorder of tooth development which is due to aberrant deposition or composition of enamel. Both syndromic and isolated forms exist; they may be inherited in an X-linked, autosomal recessive, or autosomal dominant manner. WDR72 is one of ten currently known genes for recessive isolated AI; nine WDR72 mutations affecting single nucleotides have been described to date. Based on whole exome sequencing in a large consanguineous AI pedigree, we obtained evidence for presence of a multi-exonic WDR72 deletion. A home-made multiplex ligation-dependent probe amplification assay was used to confirm the aberration, to narrow its extent, and to identify heterozygous carriers. Our study extends the mutational spectrum for WDR72 to include large deletions, and supports a relevance of the previously proposed loss-of-function mechanism. It also introduces an easy-to-use and highly sensitive tool for detecting WDR72 copy number alterations.
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Affiliation(s)
- Julia Hentschel
- Institute of Human Genetics, Jena University Hospital, Jena, Germany; Institute of Human Genetics, University of Leipzig Hospitals and Clinics, Leipzig, Germany
| | - Dana Tatun
- Institute of Medical and Human Genetics, Charité, Universitaetsmedizin Berlin, Germany
| | - Dmitri Parkhomchuk
- Institute of Medical and Human Genetics, Charité, Universitaetsmedizin Berlin, Germany
| | - Ingo Kurth
- Institute of Human Genetics, Jena University Hospital, Jena, Germany
| | - Bettina Schimmel
- Institute of Human Genetics, Jena University Hospital, Jena, Germany
| | | | | | - Hartmut Peters
- Institute of Medical and Human Genetics, Charité, Universitaetsmedizin Berlin, Germany; ChariteVivantes GmbH, Berlin, Germany
| | - Christian Beetz
- Department of Clinical Chemistry and Laboratory Medicine, Jena University Hospital, Jena, Germany.
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Wang SK, Hu Y, Yang J, Smith CE, Nunez SM, Richardson AS, Pal S, Samann AC, Hu JCC, Simmer JP. Critical roles for WDR72 in calcium transport and matrix protein removal during enamel maturation. Mol Genet Genomic Med 2015; 3:302-19. [PMID: 26247047 PMCID: PMC4521966 DOI: 10.1002/mgg3.143] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Revised: 03/02/2015] [Accepted: 03/02/2015] [Indexed: 12/19/2022] Open
Abstract
Defects in WDR72 (WD repeat-containing protein 72) cause autosomal recessive hypomaturation amelogenesis imperfecta. We generated and characterized Wdr72-knockout/lacZ-knockin mice to investigate the role of WDR72 in enamel formation. In all analyses, enamel formed by Wdr72 heterozygous mice was indistinguishable from wild-type enamel. Without WDR72, enamel mineral density increased early during the maturation stage but soon arrested. The null enamel layer was only a tenth as hard as wild-type enamel and underwent rapid attrition following eruption. Despite the failure to further mineralize enamel deposited during the secretory stage, ectopic mineral formed on the enamel surface and penetrated into the overlying soft tissue. While the proteins in the enamel matrix were successfully degraded, the digestion products remained inside the enamel. Interactome analysis of WDR72 protein revealed potential interactions with clathrin-associated proteins and involvement in ameloblastic endocytosis. The maturation stage mandibular incisor enamel did not stain with methyl red, indicating that the enamel did not acidify beneath ruffle-ended ameloblasts. Attachment of maturation ameloblasts to the enamel layer was weakened, and SLC24A4, a critical ameloblast calcium transporter, did not localize appropriately along the ameloblast distal membrane. Fewer blood vessels were observed in the papillary layer supporting ameloblasts. Specific WDR72 expression by maturation stage ameloblasts explained the observation that enamel thickness and rod decussation (established during the secretory stage) are normal in the Wdr72 null mice. We conclude that WDR72 serves critical functions specifically during the maturation stage of amelogenesis and is required for both protein removal and enamel mineralization.
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Affiliation(s)
- Shih-Kai Wang
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry 1210 Eisenhower Pl., Ann Arbor, Michigan, 48108
| | - Yuanyuan Hu
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry 1210 Eisenhower Pl., Ann Arbor, Michigan, 48108
| | - Jie Yang
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry 1210 Eisenhower Pl., Ann Arbor, Michigan, 48108 ; Department of Pediatric Dentistry, School and Hospital of Stomatology, Peking University 22 South Avenue Zhongguancun, Haidian District, Beijing, 100081, China
| | - Charles E Smith
- Facility for Electron Microscopy Research, Department of Anatomy and Cell Biology and Faculty of Dentistry, McGill University 3640 University Street, Montreal, Quebec, Canada, H3A 2B2
| | - Stephanie M Nunez
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry 1210 Eisenhower Pl., Ann Arbor, Michigan, 48108
| | - Amelia S Richardson
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry 1210 Eisenhower Pl., Ann Arbor, Michigan, 48108
| | - Soumya Pal
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry 1210 Eisenhower Pl., Ann Arbor, Michigan, 48108
| | - Andrew C Samann
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry 1210 Eisenhower Pl., Ann Arbor, Michigan, 48108
| | - Jan C-C Hu
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry 1210 Eisenhower Pl., Ann Arbor, Michigan, 48108
| | - James P Simmer
- Department of Biologic and Materials Sciences, University of Michigan School of Dentistry 1210 Eisenhower Pl., Ann Arbor, Michigan, 48108
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Katsura KA, Horst JA, Chandra D, Le TQ, Nakano Y, Zhang Y, Horst OV, Zhu L, Le MH, DenBesten PK. WDR72 models of structure and function: a stage-specific regulator of enamel mineralization. Matrix Biol 2014; 38:48-58. [PMID: 25008349 PMCID: PMC4185229 DOI: 10.1016/j.matbio.2014.06.005] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2013] [Revised: 06/21/2014] [Accepted: 06/26/2014] [Indexed: 12/18/2022]
Abstract
Amelogenesis Imperfecta (AI) is a clinical diagnosis that encompasses a group of genetic mutations, each affecting processes involved in tooth enamel formation and thus, result in various enamel defects. The hypomaturation enamel phenotype has been described for mutations involved in the later stage of enamel formation, including Klk4, Mmp20, C4orf26, and Wdr72. Using a candidate gene approach we discovered a novel Wdr72 human mutation in association with AI to be a 5-base pair deletion (c.806_810delGGCAG; p.G255VfsX294). To gain insight into the function of WDR72, we used computer modeling of the full-length human WDR72 protein structure and found that the predicted N-terminal sequence forms two beta-propeller folds with an alpha-solenoid tail at the C-terminus. This domain iteration is characteristic of vesicle coat proteins, such as beta'-COP, suggesting a role for WDR72 in the formation of membrane deformation complexes to regulate intracellular trafficking. Our Wdr72 knockout mouse model (Wdr72(-/-)), containing a LacZ reporter knock-in, exhibited hypomineralized enamel similar to the AI phenotype observed in humans with Wdr72 mutations. MicroCT scans of Wdr72(-/-) mandibles affirmed the hypomineralized enamel phenotype occurring at the onset of the maturation stage. H&E staining revealed a shortened height phenotype in the Wdr72(-/-) ameloblasts with retained proteins in the enamel matrix during maturation stage. H(+)/Cl(-) exchange transporter 5 (CLC5), an early endosome acidifier, was co-localized with WDR72 in maturation-stage ameloblasts and decreased in Wdr72(-/-) maturation-stage ameloblasts. There were no obvious differences in RAB4A and LAMP1 immunostaining of Wdr72(-/-) mice as compared to wildtype controls. Moreover, Wdr72(-/-) ameloblasts had reduced amelogenin immunoreactivity, suggesting defects in amelogenin fragment resorption from the matrix. These data demonstrate that WDR72 has a major role in enamel mineralization, most notably during the maturation stage, and suggest a function involving endocytic vesicle trafficking, possibly in the removal of amelogenin proteins.
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Affiliation(s)
- K A Katsura
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of California, San Francisco, 513 Parnassus Ave., San Francisco, CA 94143-0422, USA
| | - J A Horst
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of California, San Francisco, 513 Parnassus Ave., San Francisco, CA 94143-0422, USA
| | - D Chandra
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of California, San Francisco, 513 Parnassus Ave., San Francisco, CA 94143-0422, USA
| | - T Q Le
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of California, San Francisco, 513 Parnassus Ave., San Francisco, CA 94143-0422, USA
| | - Y Nakano
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of California, San Francisco, 513 Parnassus Ave., San Francisco, CA 94143-0422, USA
| | - Y Zhang
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of California, San Francisco, 513 Parnassus Ave., San Francisco, CA 94143-0422, USA
| | - O V Horst
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of California, San Francisco, 513 Parnassus Ave., San Francisco, CA 94143-0422, USA
| | - L Zhu
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of California, San Francisco, 513 Parnassus Ave., San Francisco, CA 94143-0422, USA
| | - M H Le
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of California, San Francisco, 513 Parnassus Ave., San Francisco, CA 94143-0422, USA
| | - P K DenBesten
- Department of Oral and Craniofacial Sciences, School of Dentistry, University of California, San Francisco, 513 Parnassus Ave., San Francisco, CA 94143-0422, USA
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