Loss of PTH 1 receptor signaling in periodontal cells drives cementum dysfunction and molar ankylosis in mice

Abstract

Parathyroid hormone 1 receptor (PTH1R) signaling is critical for mineral ion homeostasis and skeletal development. Although its role in tooth root formation and eruption is established, its specific functions in adult periodontal tissues and craniofacial integrity remain incompletely defined. Here, we investigated the craniofacial and dentoalveolar phenotypes of mice with conditional deletion of PTH1R in DMP1-Cre-expressing cells. DMP1-Cre;PTH1R^fl/fl mutant mice exhibited craniofacial alterations, including reduced maxillary length and defects in the alveolar bone surrounding the molars, as revealed by micro-computed tomography and histological analysis. The mutant mice also displayed severe periodontal ligament (PDL) loss and extensive molar ankylosis, characterized by the direct fusion of alveolar bone to tooth roots, predominantly in regions of acellular cementum. In contrast, incisor development remained unaffected. PTH1R deficiency also resulted in pathological cementum overgrowth, disrupted PDL fiber organization, and decreased expression of key PDL matrix proteins, as evidenced by immunohistochemical and molecular analyses. Mechanistically, the loss of PTH1R enhanced Smad3 phosphorylation and upregulated Osterix, thereby promoting aberrant cementoblast differentiation and mineralization. Concurrently, Dkk1 expression was increased, leading to suppressed Wnt signaling. This evidence establishes PTH1R signaling in cementocytes as a central safeguard of cementum homeostasis and PDL integrity and demonstrates that its disruption induces pathological root-bone fusion and craniofacial abnormalities. These findings advance our understanding of the molecular mechanisms underlying adult periodontal tissue maintenance and open new opportunities for developing therapeutic strategies against ankylosis and related disorders by targeting PTH1R signaling.

References

[1] Martin TJ, Sims NA, Seeman E. Physiological and pharmacological roles of PTH and PTHrP in bone using their shared receptor, PTH1R. Endocr. Rev., 2021, 42: 383-406

[2] Cheloha RW, Gellman SH, Vilardaga JP, Gardella TJ. PTH receptor-1 signalling-mechanistic insights and therapeutic prospects. Nat. Rev. Endocrinol., 2015, 11: 712-724

[3] Gardella TJ, Juppner H. Interaction of PTH and PTHrP with their receptors. Rev. Endocr. Metab. Disord., 2000, 1: 317-329

[4] Schipani E, Provot S. PTHrP, PTH, and the PTH/PTHrP receptor in endochondral bone development. Birth Defects Res C. Embryo Today, 2003, 69: 352-362

[5] Lyu P, et al.. Parathyroid hormone 1 receptor signaling in dental mesenchymal stem cells: basic and clinical implications. Front. Cell Dev. Biol., 2021, 9 Article ID: 654715

[6] Grippaudo C, Cafiero C, D’Apolito I, Ricci B, Frazier-Bowers SA. Primary failure of eruption: Clinical and genetic findings in the mixed dentition. Angle Orthod., 2018, 88: 275-282

[7] Subramanian H, et al.. PTH1R mutants found in patients with primary failure of tooth eruption disrupt G-protein signaling. PLoS One, 2016, 11: e0167033

[8] Lu K, et al.. A novel PTH1R mutation causes primary failure of eruption via the cAMP-PI3K/AKT pathway. Prog. Orthod., 2025, 26 Article ID: 7

[9] Wang J, Zhao C, Zhang X, Yang L, Hu Y. Identification of a novel heterozygous PTH1R variant in a Chinese family with incomplete penetrance. Mol. Genet Genom. Med, 2024, 12 Article ID: e2301

[10] Zha Y, et al.. Identification of a novel PTH1R variant in a family with primary failure of eruption. BMC Oral. Health, 2023, 23 Article ID: 509

[11] Frazier-Bowers SA, Simmons D, Wright JT, Proffit WR, Ackerman JL. Primary failure of eruption and PTH1R: the importance of a genetic diagnosis for orthodontic treatment planning. Am. J. Orthod. Dentofac. Orthop., 2010, 137: 160 e161-160 e167

[12] Lanske B, et al.. PTH/PTHrP receptor in early development and Indian hedgehog-regulated bone growth. Science, 1996, 273: 663-666

[13] Portales-Castillo I, Dean T, Khatri A, Juppner H, Gardella TJ. Functional properties of two distinct PTH1R mutants associated with either skeletal defects or pseudohypoparathyroidism. JBMR., 2022, 6 Article ID: e10604

[14] Cui C, et al.. Role of PTH1R signaling in Prx1(+) mesenchymal progenitors during eruption. J. Dent. Res., 2020, 99: 1296-1305

[15] Ono W, Sakagami N, Nishimori S, Ono N, Kronenberg HM. Parathyroid hormone receptor signalling in osterix-expressing mesenchymal progenitors is essential for tooth root formation. Nat. Commun., 2016, 7 Article ID: 11277

[16] Takahashi A, et al.. Autocrine regulation of mesenchymal progenitor cell fates orchestrates tooth eruption. Proc. Natl. Acad. Sci. USA, 2019, 116: 575-580

[17] Fan, Y. et al. Negative feedback between PTH1R and IGF1 through the Hedgehog pathway in mediating craniofacial bone remodeling. JCI Insight10, e183684 (2024).

[18] Nagata, M., Chu, A. K. Y., Ono, N., Welch, J. D. & Ono, W. Single-cell transcriptomic analysis reveals developmental relationships and specific markers of mouse periodontium cellular subsets. Front Dent. Med.2, 679937 (2021).

[19] Matthews BG, et al.. Gene-expression analysis of cementoblasts and osteoblasts. J. Periodontal Res., 2016, 51: 304-312

[20] Dangaria SJ, Ito Y, Luan X, Diekwisch TG. Differentiation of neural-crest-derived intermediate pluripotent progenitors into committed periodontal populations involves unique molecular signature changes, cohort shifts, and epigenetic modifications. Stem Cells Dev., 2011, 20: 39-52

[21] Keller H, Kneissel M. SOST is a target gene for PTH in bone. Bone, 2005, 37: 148-158

[22] O’Brien CA, et al.. Control of bone mass and remodeling by PTH receptor signaling in osteocytes. PLoS One, 2008, 3: e2942

[23] Qiu T, et al.. TGF-beta type II receptor phosphorylates PTH receptor to integrate bone remodelling signalling. Nat. Cell Biol., 2010, 12: 224-234

[24] Choi H, et al.. TGF-beta signaling regulates cementum formation through osterix expression. Sci. Rep., 2016, 6 Article ID: 26046

[25] Cao Z, et al.. Osterix controls cementoblast differentiation through downregulation of Wnt-signaling via enhancing DKK1 expression. Int. J. Biol. Sci., 2015, 11: 335-344

[26] Zhang C, Dai H, de Crombrugghe B. Characterization of Dkk1 gene regulation by the osteoblast-specific transcription factor Osx. Biochem. Biophys. Res. Commun., 2012, 420: 782-786

[27] Sack U, et al.. S100A4-induced cell motility and metastasis is restricted by the Wnt/beta-catenin pathway inhibitor calcimycin in colon cancer cells. Mol. Biol. Cell, 2011, 22: 3344-3354

[28] Stein U, et al.. The metastasis-associated gene S100A4 is a novel target of beta-catenin/T-cell factor signaling in colon cancer. Gastroenterology, 2006, 131: 1486-1500

[29] Duarte WR, et al.. Extracellular role of S100A4 calcium-binding protein in the periodontal ligament. Biochem. Biophys. Res. Commun., 1999, 255: 416-420

[30] Duarte WR, et al.. S100A4: a novel negative regulator of mineralization and osteoblast differentiation. J. Bone Miner. Res., 2003, 18: 493-501

[31] Delgado-Calle J, et al.. Control of bone anabolism in response to mechanical loading and PTH by distinct mechanisms downstream of the PTH receptor. J. Bone Miner. Res., 2017, 32: 522-535

[32] Foster BL, et al.. The progressive ankylosis protein regulates cementum apposition and extracellular matrix composition. Cells Tissues Organs, 2011, 194: 382-405

[33] Foster BL, et al.. Central role of pyrophosphate in acellular cementum formation. PLoS One, 2012, 7: e38393

[34] Nociti FHJr., et al.. Cementum: a phosphate-sensitive tissue. J. Dent. Res., 2002, 81: 817-821

[35] Dallas SL, Xie Y, Shiflett LA, Ueki Y. Mouse cre models for the study of bone diseases. Curr. Osteoporos. Rep., 2018, 16: 466-477

[36] Bivi N, et al.. Cell autonomous requirement of connexin 43 for osteocyte survival: consequences for endocortical resorption and periosteal bone formation. J. Bone Min. Res., 2012, 27: 374-389

[37] Lu Y, et al.. DMP1-targeted Cre expression in odontoblasts and osteocytes. J. Dent. Res., 2007, 86: 320-325

[38] Mae, T. et al. Immunolocalization of enzymes/membrane transporters related to bone mineralization in the metaphyses of the long bones of parathyroid-hormone-administered mice. Medicina (Kaunas)59, 1179 (2023).

[39] Couasnay G, Madel MB, Lim J, Lee B, Elefteriou F. Sites of Cre-recombinase activity in mouse lines targeting skeletal cells. J. Bone Miner. Res, 2021, 36: 1661-1679

[40] Wu Y, et al.. Aberrantly elevated Wnt signaling is responsible for cementum overgrowth and dental ankylosis. Bone, 2019, 122: 176-183

[41] Turkkahraman H, Flanagan S, Zhu T, Bellido TM, Yuan X. The LRP5 high-bone-mass mutation causes alveolar bone accrual with minor craniofacial alteration. J. Periodontal Res., 2023, 58: 723-732

[42] Yuan X, et al.. Type 1 diabetes mellitus leads to gingivitis and an early compensatory increase in bone remodeling. J. Periodontol., 2023, 94: 277-289

[43] Huang X, et al.. Dentinogenesis and tooth-alveolar bone complex defects in BMP9/GDF2 knockout mice. Stem Cells Dev., 2019, 28: 683-694

[44] Vora SR, Camci ED, Cox TC. Postnatal ontogeny of the cranial base and craniofacial skeleton in male C57BL/6J mice: a reference standard for quantitative analysis. Front. Physiol., 2015, 6: 417

[45] Thompson T, Flanagan S, Ortega-Gonzalez D, Zhu T, Yuan X. Immediate but temporal response: the role of distal epithelial cells in wound healing. Stem Cell Rev. Rep., 2024, 20: 1587-1598

[46] Li J, et al.. Different bone remodeling levels of trabecular and cortical bone in response to changes in Wnt/beta-catenin signaling in mice. J. Orthop. Res, 2017, 35: 812-819

[47] Turkkahraman, H. et al. Sclerostin antibody corrects periodontal disease in type 2 diabetic mice. JCI Insight9, e181940 (2024).

[48] Chen J, et al.. Molecular basis for craniofacial phenotypes caused by sclerostin deletion. J. Dent. Res, 2021, 100: 310-317

[49] Foster BL, et al.. Periodontal defects in the A116T knock-in murine model of odontohypophosphatasia. J. Dent. Res., 2015, 94: 706-714

[50] Ma R, et al.. Loss of beta-catenin causes cementum hypoplasia by hampering cementogenic differentiation of Axin2-expressing cells. J. Periodontal Res., 2023, 58: 414-421

Funding

U.S. Department of Health & Human Services | NIH | National Institute of Dental and Craniofacial Research (NIDCR)(R03DE033059)

U.S. Department of Health & Human Services | NIH | National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)(R01-AR059357)

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