title: Controlling the number of tooth rows.
abstract: The organization and renewal capacity of teeth vary greatly among vertebrates. Mammals have only one row of teeth that are renewed at most once, whereas many nonmammalian species have multirowed dentitions and show remarkable capacity to replace their teeth throughout life. Although knowledge on the genetic basis of tooth morphogenesis has increased exponentially over the past 20 years, little is known about the molecular mechanisms controlling sequential initiation of multiple tooth rows or restricting tooth development to one row in mammals. Mouse genetics has revealed a pivotal role for the transcription factor Osr2 in this process. Loss of Osr2 caused expansion of the expression domain of Bmp4, a well-known activator of tooth development, leading to the induction of supernumerary teeth in a manner resembling the initiation of a second tooth row in nonmammalian species.
authors.affiliation: Institute of Biotechnology, University of Helsinki, Helsinki, Finland. marja.mikkola@helsinki.fi
authors.forename: Marja L
authors.initials: ML
authors.lastname: Mikkola
mesh_terms: D000818:Animals; D055415:Bone Morphogenetic Protein 4 / Q000502:physiology; D003817:Dentition; D004475:Ectoderm / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D053823:Hedgehog Proteins / Q000502:physiology; D018398:Homeodomain Proteins / Q000502:physiology; D006801:Humans; D051957:MSX1 Transcription Factor / Q000172:deficiency / Q000502:physiology; D008322:Mammals / Q000033:anatomy & histology / Q000196:embryology / Q000235:genetics / Q000254:growth & development; D008648:Mesoderm / Q000502:physiology; D051379:Mice / Q000033:anatomy & histology* / Q000196:embryology / Q000254:growth & development; D018345:Mice, Knockout; D009805:Odontogenesis / Q000235:genetics / Q000502:physiology*; D012038:Regeneration / Q000235:genetics / Q000502:physiology; D013045:Species Specificity; D014096:Tooth, Supernumerary / Q000196:embryology / Q000235:genetics; D014157:Transcription Factors / Q000172:deficiency / Q000502:physiology; D014714:Vertebrates / Q000033:anatomy & histology* / Q000196:embryology / Q000235:genetics / Q000254:growth & development; D000097577:Homeobox Protein PITX2
chemical_list: D055415:Bone Morphogenetic Protein 4; D053823:Hedgehog Proteins; D018398:Homeodomain Proteins; D051957:MSX1 Transcription Factor; D014157:Transcription Factors; D000097577:Homeobox Protein PITX2; C484084:Msx1 protein, mouse; C438618:Osr2 protein, mouse; C465570:Shh protein, mouse