title: Expression and function of NUMB in odontogenesis.
abstract: NUMB is a multifunctional protein implicated to function in self-renewal and differentiation of progenitors in several tissues. To characterize the transcripts and to analyze the expression pattern of NUMB in odontogenesis, we isolated 2 full-length clones for NUMB from mouse dental pulp mRNA. One novel sequence contained 200 bp insertion in the phosphotyrosine binding domain (PTB). Confocal microscopy analysis showed strong NUMB expression in human dental pulp stem cells (hDPSC) and preameloblasts. Western blot analysis indicated that NUMB isoforms were differentially expressed in various dental tissues. Immunohistochemical analysis showed that in postnatal mouse tooth germs, NUMB was differentially expressed in the preameloblasts, odontoblasts, cervical loop region, and in the dental pulp stem cells during development. Interestingly, overexpression of NUMB in HAT-7, a preameloblast cell line, had dramatic antagonizing effects on the protein expression level of activated Notch 1. Further analysis of the Notch signaling pathway showed that NUMB significantly downregulates sonic hedgehog (Shh) expression in preameloblasts. Therefore, we propose that NUMB maintains ameloblast progenitor phenotype at the cervical loop by downregulating the activated Notch1 protein and thereby inhibiting the mRNA expression of Shh.
authors.affiliation: Department of Orthodontics, College of Dental Medicine, Nova Southeastern University, 3200 S. University Drive, Fort Lauderdale, FL 33328, USA.
authors.forename: Haitao
authors.initials: H
authors.lastname: Li
authors.forename: Amsaveni
authors.initials: A
authors.lastname: Ramachandran
authors.forename: Qi
authors.initials: Q
authors.lastname: Gao
authors.forename: Sriram
authors.initials: S
authors.lastname: Ravindran
authors.forename: Yiqiang
authors.initials: Y
authors.lastname: Song
authors.forename: Carla
authors.initials: C
authors.lastname: Evans
authors.forename: Anne
authors.initials: A
authors.lastname: George
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000235:genetics; D002460:Cell Line; D003782:Dental Pulp / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics* / Q000302:isolation & purification* / Q000378:metabolism; D051379:Mice; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000302:isolation & purification* / Q000378:metabolism; D009804:Odontoblasts / Q000378:metabolism; D009805:Odontogenesis; D012333:RNA, Messenger / Q000235:genetics* / Q000302:isolation & purification; D051881:Receptor, Notch1 / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; C106293:Numb protein, mouse; D012333:RNA, Messenger; D051881:Receptor, Notch1