title: Specialized stem cell niche enables repetitive renewal of alligator teeth.
abstract: Reptiles and fish have robust regenerative powers for tooth renewal. However, extant mammals can either renew their teeth one time (diphyodont dentition) or not at all (monophyodont dentition). Humans replace their milk teeth with permanent teeth and then lose their ability for tooth renewal. Here, we study tooth renewal in a crocodilian model, the American alligator, which has well-organized teeth similar to mammals but can still undergo life-long renewal. Each alligator tooth is a complex family unit composed of the functional tooth, successional tooth, and dental lamina. Using multiple mitotic labeling, we map putative stem cells to the distal enlarged bulge of the dental lamina that contains quiescent odontogenic progenitors that can be activated during physiological exfoliation or artificial extraction. Tooth cycle initiation correlates with β-catenin activation and soluble frizzled-related protein 1 disappearance in the bulge. The dermal niche adjacent to the dermal lamina dynamically expresses neural cell adhesion molecule, tenascin-C, and other molecules. Furthermore, in development, asymmetric β-catenin localization leads to the formation of a heterochronous and complex tooth family unit configuration. Understanding how these signaling molecules interact in tooth development in this model may help us to learn how to stimulate growth of adult teeth in mammals.
authors.affiliation: Department of Pathology, University of Southern California, Los Angeles, CA 90033, USA.
authors.forename: Ping
authors.initials: P
authors.lastname: Wu
authors.forename: Xiaoshan
authors.initials: X
authors.lastname: Wu
authors.forename: Ting-Xin
authors.initials: TX
authors.lastname: Jiang
authors.forename: Ruth M
authors.initials: RM
authors.lastname: Elsey
authors.forename: Bradley L
authors.initials: BL
authors.lastname: Temple
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Divers
authors.forename: Travis C
authors.initials: TC
authors.lastname: Glenn
authors.forename: Kuo
authors.initials: K
authors.lastname: Yuan
authors.forename: Min-Huey
authors.initials: MH
authors.lastname: Chen
authors.forename: Randall B
authors.initials: RB
authors.lastname: Widelitz
authors.forename: Cheng-Ming
authors.initials: CM
authors.lastname: Chuong
mesh_terms: D000489:Alligators and Crocodiles; D000818:Animals; D001973:Bromodeoxyuridine; D049109:Cell Proliferation; D006023:Glycoproteins / Q000378:metabolism; D017403:In Situ Hybridization; D047908:Intracellular Signaling Peptides and Proteins; D023421:Models, Animal; D008954:Models, Biological; D009805:Odontogenesis / Q000502:physiology*; D012038:Regeneration / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology*; D013234:Stem Cells / Q000502:physiology*; D019063:Tenascin / Q000378:metabolism; D014070:Tooth / Q000166:cytology / Q000502:physiology*; D055114:X-Ray Microtomography; D051176:beta Catenin / Q000378:metabolism; D000099274:Frizzled-Related Proteins
chemical_list: D001973:Bromodeoxyuridine; D006023:Glycoproteins; D047908:Intracellular Signaling Peptides and Proteins; D019063:Tenascin; D051176:beta Catenin; D000099274:Frizzled-Related Proteins
keywords: Wnt; placode; regeneration; slow cycling