title: Nephronectin plays critical roles in Sox2 expression and proliferation in dental epithelial stem cells via EGF-like repeat domains.
abstract: Tooth development is initiated by epithelial-mesenchymal interactions via basement membrane (BM) and growth factors. In the present study, we found that nephronectin (Npnt), a component of the BM, is highly expressed in the developing tooth. Npnt localizes in the BM on the buccal side of the tooth germ and shows an expression pattern opposite that of the dental epithelial stem cell marker Sox2. To identify the roles of Npnt during tooth development, we performed knockdown and overexpression experiments using ex vivo organ and dental epithelial cell cultures. Our findings showed that loss of Npnt induced ectopic Sox2-positive cells and reduced tooth germ size. Over expression of Npnt showed increased proliferation, whereas the number of Sox2-positive cells was decreased in dental epithelial cells. Npnt contains 5 EGF-like repeat domains, as well as an RGD sequence and MAM domain. We found that the EGF-like repeats are critical for Sox2 expression and cell proliferation. Furthermore, Npnt activated the EGF receptor (EGFR) via the EGF-like repeat domains and induced the PI3K-Akt signaling pathway. Our results indicate that Npnt plays a critical scaffold role in dental epithelial stem cell differentiation and proliferation, and regulates Sox2 expression during tooth development.
authors.affiliation: Section of Orthodontics and Dentofacial Orthopedics, Division of Oral Health, Growth and Development, Faculty of Dental Science, Kyushu University, Fukuoka 812-8582, Japan.
authors.forename: Chieko
authors.initials: C
authors.lastname: Arai
authors.affiliation: Section of Orthodontics and Dentofacial Orthopedics, Division of Oral Health, Growth and Development, Faculty of Dental Science, Kyushu University, Fukuoka 812-8582, Japan.
authors.forename: Keigo
authors.initials: K
authors.lastname: Yoshizaki
authors.affiliation: Section of Orthodontics and Dentofacial Orthopedics, Division of Oral Health, Growth and Development, Faculty of Dental Science, Kyushu University, Fukuoka 812-8582, Japan.
authors.forename: Kanako
authors.initials: K
authors.lastname: Miyazaki
authors.affiliation: Division of Pediatric Dentistry, Department of Oral Health and Development Sciences, Tohoku University Graduate School of Dentistry, Sendai 980-8575, Japan.
authors.forename: Kan
authors.initials: K
authors.lastname: Saito
authors.affiliation: Division of Pediatric Dentistry, Department of Oral Health and Development Sciences, Tohoku University Graduate School of Dentistry, Sendai 980-8575, Japan.
authors.forename: Aya
authors.initials: A
authors.lastname: Yamada
authors.affiliation: Section of Orthodontics and Dentofacial Orthopedics, Division of Oral Health, Growth and Development, Faculty of Dental Science, Kyushu University, Fukuoka 812-8582, Japan.
authors.forename: Xue
authors.initials: X
authors.lastname: Han
authors.affiliation: Section of Orthodontics and Dentofacial Orthopedics, Division of Oral Health, Growth and Development, Faculty of Dental Science, Kyushu University, Fukuoka 812-8582, Japan.
authors.forename: Keita
authors.initials: K
authors.lastname: Funada
authors.affiliation: Division of Pediatric Dentistry, Department of Oral Health and Development Sciences, Tohoku University Graduate School of Dentistry, Sendai 980-8575, Japan.
authors.forename: Emiko
authors.initials: E
authors.lastname: Fukumoto
authors.affiliation: Section of Orthodontics and Dentofacial Orthopedics, Division of Oral Health, Growth and Development, Faculty of Dental Science, Kyushu University, Fukuoka 812-8582, Japan.
authors.forename: Naoto
authors.initials: N
authors.lastname: Haruyama
authors.affiliation: Department of Pediatric Dentistry, Institute of Biomedical Science, Tokushima University Graduate School, Tokushima 770-8540, Japan.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Iwamoto
authors.affiliation: Section of Orthodontics and Dentofacial Orthopedics, Division of Oral Health, Growth and Development, Faculty of Dental Science, Kyushu University, Fukuoka 812-8582, Japan.
authors.forename: Ichiro
authors.initials: I
authors.lastname: Takahashi
authors.affiliation: Division of Pediatric Dentistry, Department of Oral Health and Development Sciences, Tohoku University Graduate School of Dentistry, Sendai 980-8575, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Fukumoto
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D002460:Cell Line; D049109:Cell Proliferation; D066246:ErbB Receptors / Q000378:metabolism; D016326:Extracellular Matrix Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D055786:Gene Knockout Techniques; D051379:Mice; D009924:Organ Culture Techniques; D000072417:Protein Domains; D055748:SOXB1 Transcription Factors / Q000378:metabolism*; D015398:Signal Transduction; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism; D014070:Tooth / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism
chemical_list: D016326:Extracellular Matrix Proteins; C000629142:Npnt protein, mouse; D055748:SOXB1 Transcription Factors; C527783:Sox2 protein, mouse; C432915:nephronectin; C541485:EGFR protein, mouse; D066246:ErbB Receptors