title: The novel expression of Oct3/4 and Bmi1 in the root  development of mouse molars.
abstract: The root apex of the tooth elongates until the completion of root development. Although the signaling molecules inducing root elongation have been studied, the characteristic of the cells having the ability to maintain the root elongation remains unclear. This study aimed to investigate the characteristics of the cells involved in the root elongation. Octamer-binding factor 3/4 (Oct3/4) is known as one of the key regulators in maintaining the pluripotency and self-renewal properties of embryonic stem cells. Bmi1, the polycomb-group transcriptional repressor, has emerged as a key regulator in several cellular processes including stem cell self-renewal and cancer cell proliferation. At the beginning of root formation, ameloblasts expressed Oct3/4 in the nucleus, except in the apex of the cervical loop, in which Bmi1and cyclinD were expressed. At PN6, the expression of Oct3/4 in the ameloblasts shifted from the nucleus to the cytoplasm, whereas ameloblastin-negative Hertwig's epithelial root sheath (HERS) cells expressed Bmi1 and cyclinD. By PN10, the cells in the apex of HERS began to express Oct3/4 in their nucleus, whereas Bmi1 and cyclinD began to decrease in their expressions. The odontoblasts consistently expressed Oct3/4 in their cytoplasm. Our results suggest that (1) Oct3/4 creates the border between the ameloblasts from the proliferative region of HERS, (2) Bmi1-positive cells would be one of the candidates resulting in root elongation and (3) the Oct3/4 expression in the cytoplasm of odontoblasts may be related to maintain the odontoblastic characteristics.
authors.affiliation: Division in Anatomy and Developmental Biology, Department of Oral Biology, Research Center for Orofacial Hard Tissue Regeneration, Brain Korean 21 Project, Oral Science Research Center, College of Dentistry, Yonsei University, 50 Yonsei-ro, Seodaemun-Gu, Seoul 120-752, Korea.
authors.forename: Eizo
authors.initials: E
authors.lastname: Nakagawa
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
authors.forename: Jeong-Oh
authors.initials: JO
authors.lastname: Shin
authors.forename: Eun-Jung
authors.initials: EJ
authors.lastname: Kim
authors.forename: Sung-Won
authors.initials: SW
authors.lastname: Cho
authors.forename: Hayato
authors.initials: H
authors.lastname: Ohshima
authors.forename: Zhi
authors.initials: Z
authors.lastname: Chen
authors.forename: Han-Sung
authors.initials: HS
authors.lastname: Jung
mesh_terms: D000818:Animals; D051379:Mice; D008813:Mice, Inbred ICR; D008963:Molar / Q000254:growth & development*; D009687:Nuclear Proteins / Q000378:metabolism*; D009804:Odontoblasts / Q000378:metabolism; D009805:Odontogenesis; D027701:Organic Cation Transport Proteins / Q000378:metabolism*; D063150:Polycomb Repressive Complex 1; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D012097:Repressor Proteins / Q000378:metabolism*; D014092:Tooth Root / Q000254:growth & development* / Q000378:metabolism; D000099254:Organic Cation Transporter 3
chemical_list: D009687:Nuclear Proteins; D027701:Organic Cation Transport Proteins; D063150:Polycomb Repressive Complex 1; D011518:Proto-Oncogene Proteins; D012097:Repressor Proteins; D000099254:Organic Cation Transporter 3; C489421:Bmi1 protein, mouse