Tenascin-C promotes differentiation of rat dental pulp cells in vitro.
ABSTRACT AIM: To investigate the effects of tenascin-C (TN-C) on cultured rat dental pulp cells in relation to the expression of Notch signalling. METHODOLOGY: Subcultured dental pulp cells derived from rat incisors were seeded both in wells and on plastic coverslips coated with various concentrations of recombinant human TN-C. Expression of bone-related mRNA was then analysed by RT-PCR and observed by immunohistochemical staining. Encoding of Notch1 and Notch2 (markers of initial differentiation of odontoblast-like cells), alkaline phosphatase (ALP), osteopontin (OPN) and osteocalcin (OCN) (markers of mineralization) was investigated. Non-TN-C-coated wells were used as controls. Primary antibodies to Notch1, ALP and OCN were used for immunofluorescence staining, and ALP activity was evaluated. Data were compared using Student's t-test. RESULTS: Cell proliferation rate in the experimental groups was significantly higher (P < 0.05) than that in the control group at 72 h. Expression of Notch1, Notch2, ALP, OPN and OCN mRNAs was significantly higher (P < 0.05) in the experimental group than that in the control group. Strongly positive staining for Notch1, ALP and OCN was observed in the experimental group. ALP activity was significantly higher (P < 0.01) in the experimental group than in the control group at 24 h. CONCLUSION: TN-C promoted differentiation of rat dental pulp cells by the activation of Notch.
SourceAvailable from: Thimios A Mitsiadis[Show abstract] [Hide abstract]
ABSTRACT: Serrate-like genes encode transmembrane ligands to Notch receptors and control cell fate decisions during development. In this report, we analyse the regulation of the mouse Serrate-1 gene during embryogenesis. The Serrate-1 gene is expressed from embryonic day 7.5 (E7.5) and expression is often observed at sites of epithelial-mesenchymal interactions, including the developing tooth, where Serrate-1 is first (E11.5) expressed in all cells of the dental epithelium, but not in mesenchyme. A transient upregulation in dental mesenchyme (E12.5-15.5) is correlated with down-regulation of Serrate-1 expression in epithelial cells contacting the mesenchyme, i.e. in the cells destined to become ameloblasts. This expression pattern is reproduced in explants of dental epithelium and mesenchyme in vitro: epithelium induces Serrate-1 expression in mesenchyme, while epithelium in close proximity to this mesenchyme does not express detectable levels of Serrate-1 mRNA, suggesting that down-regulation of Serrate-1 expression in preameloblasts is caused by mesenchyme-derived signals. Finally, regulation of Serrate-1 expression differs from that of Notch genes. The Serrate-1 gene is induced in dental mesenchyme by fibroblast growth factor-4, but not by bone morphogenetic proteins, while the converse is true for Notch genes. This indicates that, at least during tooth development, the expression patterns observed for receptors and ligands in the Notch signaling pathway are generated by different induction mechanisms.Development 05/1997; 124(8):1473-83. · 6.27 Impact Factor
[Show abstract] [Hide abstract]
ABSTRACT: The reparative mechanisms that operate following carious and traumatic dental injury are critical for pulp survival and involve a series of highly conserved processes. It appears that these processes share genetic programs-linked to cytoskeletal organization, cell movement, and differentiation-that occur throughout embryogenesis. Reactionary dentin is secreted by surviving odontoblasts in response to moderate stimuli, leading to an increase in metabolic activity. In severe injury, necrotic odontoblasts are replaced by other pulp cells, which are able to differentiate into odontoblast-like cells and produce a reparative dentin. This complex process requires the collaborative efforts of cells of different lineage. The behavior of each of the contributing cell types during the phases of proliferation, migration, and matrix synthesis as well as details of how growth factors control wound cell activities are beginning to emerge. In this review, we discuss what is known about the molecular mechanisms involved in dental repair.Journal of Dental Research 01/2005; 83(12):896-902. DOI:10.1177/154405910408301202 · 4.14 Impact Factor
[Show abstract] [Hide abstract]
ABSTRACT: The large, multidomain extracellular matrix protein tenascin displays a markedly restricted tissue distribution during embryogenesis and remains present only in a few adult tissues. The protein is reexpressed, however, during wound healing and in the stroma of malignant tumours. While a variety of studies have dealt with the important role of tenascin in the development of neural and non-neural tissues, there is growing evidence that tenascin expression may be associated with proliferation of cells lining these tissues. The presence of repeating domains in tenascin similar to those in epidermal growth factor prompted us to investigate the ability of tenascin to modulate the growth of different cell types. Tenascin was actually found to be mitogenic for several cell types. This mitogenic activity, however, appears to be associated with a region in the fibronectin type III domains. The mitogenic mechanism is clearly distinct from pathways used by peptide growth factors such as epidermal growth factor and platelet-derived growth factor, which activate the intrinsic tyrosine kinase activity of their cell-surface receptors. However, we show that this large extracellular matrix molecule is efficiently internalised and may be processed by responding cells.European Journal of Biochemistry 12/1992; 209(3):1041-51. DOI:10.1111/j.1432-1033.1992.tb17380.x · 3.58 Impact Factor