Essential roles of G9a in cell proliferation and differentiation during tooth development

Autor: Kamiunten, T., Ideno, H., Shimada, A., Arai, Y., Terashima, T., Tomooka, Y., Nakamura, Y., Nakashima, K., Kimura, Hiroshi, Shinkai, Y., Tachibana, M., Nifuji, A.
Jazyk: angličtina
Rok vydání: 2017
Předmět:
0301 basic medicine
endocrine system
Mesenchyme
Mice
Transgenic
SOX9
Biology
Bone morphogenetic protein
Epithelium
Mesoderm
03 medical and health sciences
Cranial neural crest
FGF9
stomatognathic system
Tooth/*growth & development
Conditional gene knockout
medicine
Animals
Transcription Factors/metabolism
Differentiation
Cell Proliferation
Epigenetics
Odontogenesis/physiology
FGF10
Inner enamel epithelium
Bone Morphogenetic Proteins/metabolism
Gene Expression Regulation
Developmental
Cell Differentiation
Fibroblast Growth Factors/metabolism
Cell Biology
Histone-Lysine N-Methyltransferase
Cell Proliferation/*physiology
Cell biology
Fibroblast Growth Factors
Cell Differentiation/*physiology
Epithelium/metabolism
stomatognathic diseases
030104 developmental biology
medicine.anatomical_structure
Histone-Lysine N-Methyltransferase/genetics/*metabolism
Tooth development
Mesoderm/cytology
Immunology
Bone Morphogenetic Proteins
embryonic structures
Odontogenesis
Tooth
Gene Expression Regulation
Developmental/*physiology
Transcription Factors
Zdroj: Experimental cell research. 357(No. 2):202-210
ISSN: 0014-4827
Popis: Teeth develop through interactions between epithelial and mesenchymal tissues mediated by a signaling network comprised of growth factors and transcription factors. However, little is known about how epigenetic modifiers affect signaling pathways and thereby regulate tooth formation. We previously reported that the histone 3 lysine 9 (H3K9) methyltransferase (MTase) G9a is specifically enriched in the tooth mesenchyme during mouse development. In this study, we investigated the functions of G9a in tooth development using G9a conditional knockout (KO) mice. We used Sox9-Cre mice to delete G9a in the tooth mesenchyme because Sox9 is highly expressed in the mesenchyme derived from the cranial neural crest. Immunohistochemical analyses revealed that G9a expression was significantly decreased in the mesenchyme of Sox9-Cre;G9afl/fl (G9a cKO) mice compared with that in Sox9-Cre;G9a fl/+(control) mice. Protein levels of the G9a substrate H3K9me2 were also decreased in the tooth mesenchyme. G9a cKO mice showed smaller tooth germ after embryonic day (E) 16.5 and E17.5, but not at E15.5. The developing cusp tips, which were visible in control mice, were absent in G9a cKO mice at E17.5. At 3 weeks after birth, small first molars with smaller cusps and unseparated roots were formed. Organ culture of tooth germs derived from E15.5 cKO mouse embryos showed impaired tooth development, suggesting that tooth development per se is affected independently of skull development. BrdU labeling experiments revealed that the proliferation rates were decreased in the mesenchyme in G9a cKO mice at E17.5. In addition, the proliferation rates in the tooth inner enamel epithelium were also decreased. In situ hybridization revealed altered localization of genes associated with tooth development. In cKO mice, intensively localized expression of mRNAs encoding bone morphogenic protein (Bmp2 and Bmp4) was observed in the tooth mesenchyme at E17.5, similar to the expression patterns observed in control mice at E15.5. Localization of Shh and related signaling components, including Gli1, Ptch1, and Ptch2, in the tooth mesenchyme of cKO mice was generally similar to that at earlier stages in control mice. In addition, expression of Fgf3 and Fgf10 in the mesenchyme was decreased in G9a cKO mice at P0. Expression levels of Fgf9 and p21, both of which were expressed in the secondary enamel-knot, were also decreased. Thus, the expression of genes associated with tooth development was delayed in cKO mice. Our results suggest that H3K9MTase G9a regulates cell proliferation and timing of differentiation and that G9a expression in the tooth mesenchyme is required for proper tooth development.
Databáze: OpenAIRE
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