Skip to main content

Mkx regulates the orthodontic tooth movement via osteoclast induction



The periodontal ligament (PDL) plays an important role in orthodontic tooth movement; however, the underlying molecular mechanism remains unclear. We have previously reported that the Mohawk homeobox (Mkx), a tendon-specific transcription factor, is expressed in the PDL and regulates its homeostasis.

Materials and methods

In the present study, we examined the role of Mkx in orthodontic tooth movement via bone remodeling induced by mechanical stimulation in Mkx-deficient rats, which are widely used as experimental animals for orthodontic force application. Orthodontic tooth movement of the maxillary first molar was performed in 7-week-old male Mkx-deficient rats (n = 4) and wild-type Wistar rats (n = 4) using coil springs for 14 days. Hematoxylin and eosin (H&E) staining and tartrate-resistant acid phosphatase (TRAP) staining were performed to evaluate morphological changes and osteoclasts. Furthermore, changes in the expression of receptor activator nuclear factor-kappa B ligand (RANKL) were demonstrated using immunostaining.


The amount of tooth movement was significantly lower in Mkx-deficient rats than in wild-type rats. The number of TRAP-positive cells was suppressed in Mkx-deficient rats on the compression side.


Orthodontic tooth movement experiments in Mkx-deficient rats suggested that Mkx is involved in osteoclast induction at the alveolar bone surface on the compression side. This study reveals the possibility that Mkx plays a mechanosensory role in orthodontic tooth movement by inducing RANKL expression and osteoclastogenesis.

This is a preview of subscription content, access via your institution.

Fig. 1
Fig. 2
Fig. 3
Fig. 4


  1. 1.

    Davidovitch Z (1991) Tooth movement. Crit Rev Oral Biol Med 2:411–450.

    CAS  Article  PubMed  Google Scholar 

  2. 2.

    Oppenheim A (1944) A possibility for physiologic orthodontic movement. Am J Orthod Oral Surg 30:277–328.

    Article  Google Scholar 

  3. 3.

    Garlet TP, Coelho U, Repeke CE et al (2008) Differential expression of osteoblast and osteoclast chemmoatractants in compression and tension sides during orthodontic movement. Cytokine 42:330–335.

    CAS  Article  PubMed  Google Scholar 

  4. 4.

    Masella RS, Meister M (2006) Current concepts in the biology of orthodontic tooth movement. Am J Orthod Dentofac Orthop 129:458–468.

    Article  Google Scholar 

  5. 5.

    Dubravko PJG (2001) Effect of Mechanical Loading on Periodontal Cells. Crit Rev Oral Biol Med 12:414–424

    Article  Google Scholar 

  6. 6.

    Lekic P, Sodek J, McCulloch CAG (1996) Osteopontin and bone sialoprotein expression in regenerating rat periodontal ligament and alveolar bone. Anat Rec 244:50–58.;2-J

    CAS  Article  PubMed  Google Scholar 

  7. 7.

    Takano-Yamamoto T, Takemura T, Kitamura Y, Nomura S (1994) Site-specific expression of mRNAs for osteonectin, osteocalcin, and osteopontin revealed by in situ hybridization in rat periodontal ligament during physiological tooth movement. J Histochem Cytochem 42:885–896.

    CAS  Article  PubMed  Google Scholar 

  8. 8.

    Terai K, Takano-Yamamoto T, Ohba Y et al (1999) Role of osteopontin in bone remodeling caused by mechanical stress. J Bone Miner Res 14:839–849.

    CAS  Article  PubMed  Google Scholar 

  9. 9.

    Takimoto A, Kawatsu M, Yoshimoto Y et al (2015) Scleraxis and osterix antagonistically regulate tensile force-responsive remodeling of the periodontal ligament and alveolar bone. Dev 142:787–796.

    CAS  Article  Google Scholar 

  10. 10.

    Shoji-Matsunaga A, Ono T, Hayashi M et al (2017) Osteocyte regulation of orthodontic force-mediated tooth movement via RANKL expression. Sci Rep 7:1–8.

    CAS  Article  Google Scholar 

  11. 11.

    Huang LH, Shotwell JL, Wang HL (2005) Dental implants for orthodontic anchorage. Am J Orthod Dentofac Orthop 127:713–722.

    Article  Google Scholar 

  12. 12.

    Beertsen W, Mcculloch CAG (1997) The periodontal ligament: A unique, multifunctional connective tissue. Periodontol 13:20–40.

    CAS  Article  Google Scholar 

  13. 13.

    Koda N, Sato T, Shinohara M et al (2017) The transcription factor mohawk homeobox regulates homeostasis of the periodontal ligament. Dev 144:313–320.

    CAS  Article  Google Scholar 

  14. 14.

    Ren Y, Maltha JC, Kuijpers-Jagtman AM (2004) The rat as a model for orthodontic tooth movement—a critical review and a proposed solution. Eur J Orthod 26:483–490.

    Article  PubMed  Google Scholar 

  15. 15.

    Suzuki H, Ito Y, Shinohara M et al (2016) Gene targeting of the transcription factor Mohawk in rats causes heterotopic ossification of Achilles tendon via failed tenogenesis. Proc Natl Acad Sci U S A 113:7840–7845.

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  16. 16.

    Ito Y, Toriuchi N, Yoshitaka T et al (2010) The Mohawk homeobox gene is a critical regulator of tendon differentiation. Proc Natl Acad Sci U S A 107:10538–10542.

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  17. 17.

    Gonzales C, Hotokezaka H, Yoshimatsu M et al (2008) Force magnitude and duration effects on amount of tooth movement and root resorption in the rat molar. Angle Orthod 78:502–509.

    Article  PubMed  Google Scholar 

  18. 18.

    Schneider CA, Rasband WS, Eliceiri KW (2012) NIH Image to ImageJ: 25 years of image analysis. Nat Methods 9:671–675.

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  19. 19.

    Ogasawara T, Yoshimine Y, Kiyoshima T et al (2004) In situ expression of RANKL, RANK, osteoprotegerin and cytokines in osteoclasts of rat periodontal tissue. J Periodontal Res 39:42–49.

    CAS  Article  PubMed  Google Scholar 

  20. 20.

    Kim T, Handa A, Iida J, Yoshida S (2007) RANKL expression in rat periodontal ligament subjected to a continuous orthodontic force. Arch Oral Biol 52:244–250.

    CAS  Article  PubMed  Google Scholar 

  21. 21.

    Nakamichi R, Ito Y, Inui M et al (2016) Mohawk promotes the maintenance and regeneration of the outer annulus fibrosus of intervertebral discs. Nat Commun 7:1–7.

    CAS  Article  Google Scholar 

  22. 22.

    Tunyogi-Csapo M, Kis-Toth K, Radacs M et al (2008) Cytokine-controlled RANKL and osteoprotegerin expression by human and mouse synovial fibroblasts: Fibroblast-mediated pathologic bone resorption. Arthritis Rheum 58:2397–2408.

    CAS  Article  PubMed  Google Scholar 

Download references


This work was supported by the Japan Society for the Promotion of Science KAKENHI (Grant No. 20H05696, 18K19603 to H.A.), NIH grant (AR050631 to H.A.), and AMED‐CREST from AMED (Grant No. JP20gm0810008 to H.A.). We are also grateful to the staff of the Department of Systems BioMedicine at Tokyo Medical and Dental University (TMDU) for their support and discussion.

Author information




T.M. designed the study, analyzed the data, and wrote the manuscript; R.K. analyzed the data and provided critical advice on the data analysis and writing of the manuscript; T.K. and K.S. performed the histological examinations; T.C., T. Matsushima., R.N., H.T., K.T, L.Y., T. Matsumoto., and Y.K. provided critical advice; K.M. and H.A. conceptualized the study and was in charge of the overall direction and planning.

Corresponding authors

Correspondence to Keiji Moriyama or Hiroshi Asahara.

Ethics declarations

Conflict of interest

The authors have no conflict of interest.

Additional information

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary Information

Below is the link to the electronic supplementary material.


Supplementary file1 (TIFF 10263 KB) Figure S1. The distance between the incisors and first molars in rats. A. Schematic diagram and actual photo of the measurement area. I: Incisal tooth, M1: First molar. B. Quantification of the distance of I - M1 in each group (n = 4). Data represent the average and error bars represent the standard error (*p < 0.05, two-tailed Student’s t-test)

Supplementary file2 (TIFF 10263 KB) Figure S2. Negative control of RANKL.


Supplementary file3 (TIFF 10263 KB) Figure S3. Comparison of the number of RANKL-positive cells (n = 4). Data represent the average and error bars represent the standard error of mean (SEM). Two-way ANOVA test showed no significance


Supplementary file4 (TIFF 10263 KB) Figure S4. Immunohistochemistry of COL 1 A1 in the tooth root compression side after tooth movement. D: Dental, PDL: Periodontal ligament, AB: Alveolar bone

About this article

Verify currency and authenticity via CrossMark

Cite this article

Miyazaki, T., Kurimoto, R., Chiba, T. et al. Mkx regulates the orthodontic tooth movement via osteoclast induction. J Bone Miner Metab 39, 780–786 (2021).

Download citation


  • Mohawk
  • PDL
  • Orthodontic tooth movement
  • Osteoclast
  • Rat