Cell cycle of the enamel knot during tooth morphogenesis

Short Communication

Abstract

Enamel knot (EK) is known to be a central organ in tooth development, especially for cusp patterning. To trace the exact position and movement among the inner dental epithelium (IDE) and EK cells, and to monitor the relationship between the EK and cusp patterning, it is essential that we understand the cell cycle status of the EK in early stages of tooth development. In this study, thymidine analogous (IdU, BrdU) staining was used to evaluate the cell cycle phase of the primary EK at the early casp stage (E13.0) and the gerbil embryo (E19) in a developing mouse embryo. The centerpiece of this study was to describe the cell cycle phasing and sequencing during proliferation in the IDE according to the expression of IdU and BrdU following their injection at calculated time points. The interval time between IdU injection and BrdU injection was set at 4 h. As a result, the cell cycle in the IDE of the mouse and gerbil was found to be synchronous. Conversely, the cell cycle in primary EKs of mice was much longer than that of the IDE. Therefore, the difference of cell cycle of the IDE and the EK is related to the diversity of cusp patterning and would provide a new insight into tooth morphogenesis.

Keywords

Enamel knot Tooth morphogenesis Cusp Cell cycle Mouse Gerbil 

Notes

Acknowledgements

We are grateful to Chengri Li for helping experiments. This study was supported by the Yonsei University College of Dentistry (6-2016-0021).

References

  1. Ahtiainen L, Uski I, Thesleff I, Mikkola ML (2016) Early epithelial signaling center governs tooth budding morphogenesis. J Cell Biol 214(6):753–767CrossRefPubMedPubMedCentralGoogle Scholar
  2. Boehm B, Westerberg H, Lesnicar-Pucko G, Raja S, Rautschka M, Cotterell J, Swoger J, Sharpe J (2010) The role of spatially controlled cell proliferation in limb bud morphogenesis. PLoS Biol 8(7):e1000420CrossRefPubMedPubMedCentralGoogle Scholar
  3. Cho SW, Lee HA, Cai J, Lee MJ, Kim JY, Ohshima H, Jung HS (2007) The primary enamel knot determines the position of the first buccal cusp in developing mouse molars. Differentiation 75:441–451CrossRefPubMedGoogle Scholar
  4. Coin R, Kieffer S, Lesot H, Vonesch JL, Ruch JV (2000) Inhibition of apoptosis in the primary enamel knot does not affect specific tooth crown morphogenesis in the mouse. Int J Dev Biol 44:389–396PubMedGoogle Scholar
  5. Jane CQ, Michael M, Ben SM, Paulette AZ, Andrea F, Alessandro B, Robert FH, John DW, David JP (2007) Pax6 controls cerebral cortical cell number by regulating exit from the cell cycle and specifies cortical cell identity by a cell autonomous mechanism. Dev Biol 302:50–65CrossRefGoogle Scholar
  6. Jernvall J, Thesleff I (2000) Reiterative signaling and patterning during mammalian tooth morphogenesis. Mech Dev 92:19–29.  https://doi.org/10.1016/S0925-4773(99)00322-6 CrossRefPubMedGoogle Scholar
  7. Jernvall J, Kettunen P, Karavanova I, Martin LB, Thesleff I (1994) Evidence for the role of the enamel knot as a control center in mammalian tooth cusp formation: non-dividing cells express growth stimulating Fgf-4 gene. Int J Dev Biol 38:463–469PubMedGoogle Scholar
  8. Jernvall J, Åberg T, Kettunen P, Keränen S, Thesleff I (1998) The life history of an embryonic signaling center: BMP-4 induces p21 and is associated with apoptosis in the mouse tooth enamel knot. Dev 125:161–169Google Scholar
  9. Jussila M, Thesleff I (2012) Signaling networks regulating tooth organogenesis and regeneration, and the specification of dental mesenchymal and epithelial cell lineages. Cold Spring Harb Perspect Biol 4:a008425.  https://doi.org/10.1101/cshperspect.a008425 CrossRefPubMedPubMedCentralGoogle Scholar
  10. Kratochwil K, Galceran J, Tontsch S, Roth W, Grosschedl R (2002) FGF4, a direct target of LEF1 and Wnt signaling, can rescue the arrest of tooth organogenesis in Lef1 −/− mice. Genes Dev 16:3173–3185CrossRefPubMedPubMedCentralGoogle Scholar
  11. Kwon HJ, Yoon KS, Jung HS (2013) Expression patterns of Ki-67, Cyclin A, and Cyclin D1 during tooth development. Korean J Phys Anthropol 26(1):41–49CrossRefGoogle Scholar
  12. Li L, Tang Q, Nakamura T, Suh JG, Ohshima H, Jung HS (2016) Fine tuning of Rac1 and RhoA alters cuspal shapes by remolding the cellular geometry. Sci Rep 28:6:37828CrossRefGoogle Scholar
  13. Martynoga B, Morrison H, Price DJ, Mason JO (2005) Foxg1 is required for specification of ventral telencephalon and region-specific regulation of dorsal telencephalic precursor proliferation and apoptosis. Dev Biol 283(1):113–127CrossRefPubMedGoogle Scholar
  14. Matalova E, Antonarakis GS, Sharpe PT, Tucker AS (2005) Cell lineage of primary and secondary enamel knots. Dev Dyn 233:754–759CrossRefPubMedGoogle Scholar
  15. Matalova E, Dubska L, Fleischmannova J, Chlastakova I, Janeckova E, Tucker AS (2010) Cell proliferation and apoptosis in the primary enamel knot measured by flow cytometry of laser microdissected samples. Oral Biol 55:570–575CrossRefGoogle Scholar
  16. Thesleff I (2003) Epithelial-mesenchymal signaling regulating tooth morphogenesis. J Cell Sci 116:1647–1648CrossRefPubMedGoogle Scholar
  17. Thesleff I, Keranen S, Jernvall J (2001) Enamel knots as signaling centers linking tooth morphogenesis and odontoblast differentiation. Adv Dent Res 15:14–18CrossRefPubMedGoogle Scholar
  18. Tucker AS, Headon DJ, Schneider P, Ferguson BM, Overbeek P, Tschopp J, Sharpe PT (2000) Edar/Eda interactions regulate enamel knot formation in tooth morphogenesis. Development 127:4691–4700PubMedGoogle Scholar

Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Division in Anatomy and Developmental Biology, Department of Oral Biology, Oral Science Research Center, BK21 PLUS ProjectYonsei University College of DentistrySeoulSouth Korea
  2. 2.Applied Oral Biosciences, Faculty of DentistryThe University of Hong KongHong KongHong Kong, SAR

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