Abstract
Epiprofin/Specificity Protein 6 (Epfn) is a Krüppel-like family (KLF) transcription factor that is critically involved in tooth morphogenesis and dental cell differentiation. However, its mechanism of action is still not fully understood. We have employed both loss-of-function and gain-of-function approaches to address the role of Epfn in the formation of cell junctions in dental cells and in the regulation of junction-associated signal transduction pathways. We have evaluated the expression of junction proteins in bell-stage incisor and molar tooth sections from Epfn(−/−) mice and in dental pulp MDPC-23 cells overexpressing Epfn. In Epfn(−/−) mice, a dramatic reduction occurs in the expression of tight junction and adherens junction proteins and of the adherens-junction-associated β-catenin protein, a major effector of canonical Wnt signaling. Loss of cell junctions and β-catenin in Epfn(−/−) mice is correlated with a clear decrease in bone morphogenetic protein 4 (BMP-4) expression, a decrease in nestin in the tooth mesenchyme, altered cell proliferation, and failure of ameloblast cell differentiation. Overexpression of Epfn in MDPC-23 cells results in an increased cellular accumulation of β-catenin protein, indicative of upregulation of canonical Wnt signaling. Together, these results suggest that Epfn enhances canonical Wnt/β-catenin signaling in the developing dental pulp mesenchyme, a condition that promotes the activity of other downstream signaling pathways, such as BMP, which are fundamental for cellular induction and ameloblast differentiation. These altered signaling events might underlie some of the most prominent dental defects observed in Epfn(−/−) mice, such as the absence of ameloblasts and enamel, and might throw light on developmental malformations of the tooth, including hyperdontia.
References
About I, Laurent-Maquin D, Lendahl U, Mitsiadis T (2000) Nestin expression in embryonic and adult human teeth under normal and pathological conditions. Am J Pathol 157:287–295
Amen M, Liu X, Vadlamudi U, Elizondo G, Diamond E, Engelhardt JF, Amendt BA (2007) Pitx-2 and β-catenin regulate Lef-1 isoform expression. Mol Cel Biol 27:7560–7573
Aurrekoetxea M, López J, García P, Ibarretxe G, Unda F (2012) Enhanced Wnt/β-catenin signaling during tooth morphogenesis impedes cell differentiation, and leads to alterations in the structure and mineralization of the adult tooth. Biol Cell. doi:10.1111/boc.201100075
Balda M, Matter K (2009) Tight junctions and the regulation of gene expression. Biochim Biophys Acta 1788:761–767
Chen J, Lan Y, Baek JA, Gao Y, Jiang R (2009) Wnt/beta-catenin signaling plays an essential role in activation of odontogenic mesenchyme during early tooth development. Dev Biol 334:174–185
Dassule H, Lewis P, Bei M, Maas R, McMahon A (2000) Sonic hedgehog regulates growth and morphogenesis of the tooth. Development 127:4775–4785
Fujimori S, Novak H, Weissenböck M, Jussila M, Gonçalves A, Zeller R, Galloway J, Thesleff I, Hartmann C (2010) Wnt/β-catenin signaling in the dental mesenchyme regulates incisor development by regulating Bmp4. Dev Biol 348:97–106
Gritli-Linde A, Bei M, Maas R, Zhang X, Linde A, McMahon A (2002) Shh signaling within the dental epithelium is necessary for cell proliferation, growth and polarization. Development 129:5323–5337
Hanks CT, Fang D, Sun Z, Edwards CA, Butler WT (1998) Dentin-specific proteins in MDPC-23 cell line. Eur J Oral Sci 1998 (Suppl 1):260–266
Harris TJ, Tepass U (2010) Adherens junctions: from molecules to morphogenesis. Nat Rev Mol Cell Biol 11:502–514
Hertveldt V, Louryan S, Reeth T van, Drèze P, Vooren P van, Szpirer J, Szpirer C (2008) The development of several organs and appendages is impaired in mice lacking Sp6. Dev Dyn 237:883–892
Hill TP, Taketo MM, Birchmeier W, Hartmann C (2006) Multiple roles of mesenchymal beta-catenin during murine limb patterning. Development 133:1219–1229
Järvinen E, Salazar-Ciudad I, Birchmeier W, Taketo M, Jernvall J, Thesleff I (2006) Continuous tooth generation in mouse is induced by activated epithelial Wnt/beta-catenin signaling. Proc Natl Acad Sci USA 103:18627–18632
Jimenez-Rojo L, Ibarretxe G, Aurrekoetxea M, Vega S de, Nakamura T, Yamada Y, Unda F (2010a) Epiprofin/Sp6: a new player in the regulation of tooth development. Histol Histopathol 25:1621–1630
Jimenez-Rojo L, Aurrekoetxea M, Ibarretxe G, García P, Vega S de, Unda F (2010b) Reduced expression of tight junction proteins ZO-1 and claudin-1 in ameloblasts and odontoblasts of Epiprofin/Sp6 deficient mice. Bull GIRSO 49:102–103
Kim TH, Lee J, Baek J, Lee JC, Yang X, Taketo M, Jiang R, Cho ES (2011) Constitutive stabilization of β-catenin in the dental mesenchyme leads to excessive dentin and cementum formation. Biochem Biophys Res Commun 412:549–555
Liu F, Millar SE (2010) Wnt/β-catenin signaling in oral tissue development and disease. J Dent Res 89:318–330
Munne PM, Felszeghy S, Jussila M, Suomalainen M, Thesleff I, Jernvall J (2010) Splitting placodes: effects of bone morphogenetic protein and Activin on the patterning and identity of mouse incisors. Evol Dev 12:383–392
Nakamura T, Unda F, Vega S de, Vilaxa A, Fukumoto S, Yamada K, Yamada Y (2004) The Krüppel-like factor epiprofin is expressed by epithelium of developing teeth, hair follicles, and limb buds and promotes cell proliferation. J Biol Chem 279:626–634
Nakamura T, Vega S de, Fukumoto S, Jimenez L, Unda F, Yamada Y (2008) Transcription factor epiprofin is essential for tooth morphogenesis by regulating epithelial cell fate and tooth number. J Biol Chem 283:4825–4833
Ruspita I, Miyoshi K, Muto T, Abe K, Horiguchi T, Noma T (2008) Sp6 downregulation of follistatin gene expression in ameloblasts. J Med Invest 55:87–98
Shu W, Guttentag S, Wang Z, Andl T, Ballard P, Lu MM, Piccolo S, Birchmeier W, Whitsett JA, Millar SE, Morrisey EE (2005) Wnt/beta-catenin signaling acts upstream of N-myc, BMP4, and FGF signaling to regulate proximal-distal patterning in the lung. Dev Biol 283:226–239
Talamillo A, Delgado I, Nakamura T, de-Vega S, Yoshitomi Y, Unda F, Birchmeier W, Yamada Y, Ros M (2010) Role of epiprofin, a zinc-finger transcription factor, in limb development. Dev Biol 337:363–374
Thesleff I, Tummers M (2009) Tooth organogenesis and regeneration (January 31, 2009). In: StemBook (ed) The Stem Cell Research Community, StemBook, doi: 10.3824/stembook.1.37.1, http://www.stembook.org
Tian X, Liu Z, Niu B, Zhang J, Tan TK, Lee SR, Zhao Y, Harris DC, Zheng G (2011) E-cadherin/β-catenin complex and the epithelial barrier. J Biomed Biotechnol 2011:567305
Utami TW, Miyoshi K, Hagita H, Yanuaryska RD, Horiguchi T, Noma T (2011) Possible linkage of SP6 transcriptional activity with amelogenesis by protein stabilization. J Biomed Biotechnol 2011:320987
Wang X, Suomalainen M, Jorgez C, Matzuk M, Werner S, Thesleff I (2004) Follistatin regulates enamel patterning in mouse incisors by asymmetrically inhibiting BMP signaling and ameloblast differentiation. Dev Cell 7:719–730
Wang X, O'Connell D, Lund J, Saadi I, Kuraguchi M, Turbe-Doan A, Cavallesco R, Kim H, Park P, Harada H, Kucherlapati R, Maas R (2009) Apc inhibition of Wnt signaling regulates supernumerary tooth formation during embryogenesis and throughout adulthood. Development 136:1939–1949
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This work was supported by research projects from the University of the Basque Country (UPV/EHU; GIU09/70) and Unidades de Formación e Investigación (UFI11/44), by Basque Government project grant SAIOTEK SPE11UN051, and by projects from the University of Zurich to L.J. M.A. received PhD fellowships from UPV/EHU and the Jesús Gangoiti Barrera Foundation.
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Ibarretxe, G., Aurrekoetxea, M., Crende, O. et al. Epiprofin/Sp6 regulates Wnt-BMP signaling and the establishment of cellular junctions during the bell stage of tooth development. Cell Tissue Res 350, 95–107 (2012). https://doi.org/10.1007/s00441-012-1459-8
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DOI: https://doi.org/10.1007/s00441-012-1459-8