title: Bcl11b transcription factor plays a role in the maintenance of the ameloblast-progenitors in mouse adult maxillary incisors.
abstract: Rodent incisors maintain the ability to grow continuously and their labial dentin is covered with enamel. Bcl11b zinc-finger transcription factor is expressed in ameloblast progenitors in mouse incisors and its absence in Bcl11b(KO/KO) mice results in a defect in embryonic tooth development. However, the role of Bcl11b in incisor maintenance in adult tissue was not studied because of death at birth in Bcl11b(KO/KO) mice. Here, we examined compound heterozygous Bcl11b(S826G/KO) mice, one allele of which has an amino acid substitution of serine at position 826 for glycine, that exhibited hypoplastic maxillary incisors with lower concentrations of minerals at the enamel and the dentin, accompanying the maxillary bone hypoplasia. Histological examinations revealed hypoplasia of the labial cervical loop in incisors, shortening of the ameloblast progenitor region, and impairment in differentiation and proliferation of ameloblast-lineage cells. Interestingly, however, juvenile mice at 5days after birth did not show marked change in these phenotypes. These results suggest that attenuated Bcl11b activity impairs ameloblast progenitors and incisor maintenance. The number of BrdU label-retaining cells, putative stem cells, was lower in Bcl11b(S826G/KO) incisors, which suggests the incisor hypoplasia may be in part a result of the decreased number of stem cells. Interestingly, the level of Shh and FGF3 expressions, which are assumed to play key roles in the development and maintenance of ameloblasts and odontoblasts, was not decreased, though the expressed areas were more restricted in ameloblast progenitor and mesenchyme regions of Bcl11b(S826G/KO) incisors, respectively. Those data suggest that the incisor maintenance by Bcl11b is not directly related to the FGF epithelial-mesenchymal signaling loop including Shh but is intrinsic to ameloblast progenitors and possibly stem cells.
authors.affiliation: Division of Molecular Biology, Department of Molecular Genetics, Niigata University, Graduate School of Medical and Dental Sciences, Japan. ykatsura@med.niigata-u.ac.jp
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Katsuragi
authors.forename: Junko
authors.initials: J
authors.lastname: Anraku
authors.forename: Mitsushiro
authors.initials: M
authors.lastname: Nakatomi
authors.forename: Hiroko
authors.initials: H
authors.lastname: Ida-Yonemochi
authors.forename: Miki
authors.initials: M
authors.lastname: Obata
authors.forename: Yukio
authors.initials: Y
authors.lastname: Mishima
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Sakuraba
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Gondo
authors.forename: Yasumitsu
authors.initials: Y
authors.lastname: Kodama
authors.forename: Atsushi
authors.initials: A
authors.lastname: Nishikawa
authors.forename: Ritsuo
authors.initials: R
authors.lastname: Takagi
authors.forename: Hayato
authors.initials: H
authors.lastname: Ohshima
authors.forename: Ryo
authors.initials: R
authors.lastname: Kominami
mesh_terms: D000367:Age Factors; D000565:Ameloblasts / Q000166:cytology / Q000378:metabolism*; D019943:Amino Acid Substitution; D000818:Animals; D000831:Animals, Newborn; D002452:Cell Count; D002454:Cell Differentiation; D051518:Fibroblast Growth Factor 3 / Q000235:genetics / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D053823:Hedgehog Proteins / Q000235:genetics / Q000378:metabolism; D006579:Heterozygote; D007180:Incisor / Q000166:cytology / Q000254:growth & development / Q000378:metabolism*; D008297:Male; D008437:Maxilla / Q000166:cytology / Q000254:growth & development / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D012097:Repressor Proteins / Q000172:deficiency / Q000235:genetics*; D015398:Signal Transduction; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism*; D014158:Transcription, Genetic; D025521:Tumor Suppressor Proteins / Q000172:deficiency / Q000235:genetics*
chemical_list: C511143:Bcl11b protein, mouse; C489197:Fgf3 protein, mouse; D051518:Fibroblast Growth Factor 3; D053823:Hedgehog Proteins; D012097:Repressor Proteins; C465570:Shh protein, mouse; D025521:Tumor Suppressor Proteins
keywords: Adult stem cell; Ameloblast differentiation; Bcl11b; Cervical loop; Tooth development