title: Ameloblastin is not implicated in bone remodelling and repair.
abstract: Ameloblastin (AMBN) is an enamel matrix protein produced by ameloblasts. It has been suggested that AMBN might also be implicated in craniofacial bone formation. Our objective was to determine whether AMBN has an effect on osteogenic mineralisation and influences bone remodelling and repair. MC3T3-E1 cells were screened for endogenous expression of enamel proteins using real time PCR. Various osteogenic cells were infected with lentivirus encoding for AMBN and protein expression was verified using immunochemistry. Cultures were stained with alizarin red and mineralisation was quantified. Healing bone was probed for expression of AMBN by DNA microarray analysis. Tooth extraction, experimental tooth movement (ETM), and creation of a non-critical size bone defect in the tibia (BDT) were carried out in wild type and AMBN(Δ5-6) mutant mice. Tissues were processed for immunolabelling of AMBN and Bril, an osteoblast specific protein associated with active bone formation. MC3T3-E1 cells and healing bone showed no significant expression of AMBN. Overexpression of AMBN in osteogenic cultures induced no noticeable changes in mineralisation. In wild type mice, AMBN was immunodetected in ameloblasts and enamel, but not in normal bone, and at sites where bone remodelling and repair were induced. Bone remodelling during ETM and BDT repair in AMBN(Δ5-6) mice were not significantly different from that in wild type animals. Our results suggest that AMBN does not influence osteogenic activity in vitro under the conditions used, and does not participate in craniofacial bone remodelling under mechanical stress and in repair of non-critical size bone defects.
authors.affiliation: Laboratory for the Study of Calcified Tissues and Biomaterials, Department of Stomatology, Faculty of Dentistry, Université de Montréal, 2900 Edouard Montpetit, H3T1J4 Montréal, Québec, Canada.
authors.forename: Shingo
authors.initials: S
authors.lastname: Kuroda
authors.forename: Rima
authors.initials: R
authors.lastname: Wazen
authors.forename: Karine
authors.initials: K
authors.lastname: Sellin
authors.forename: Eiji
authors.initials: E
authors.lastname: Tanaka
authors.forename: Pierre
authors.initials: P
authors.lastname: Moffatt
authors.forename: Antonio
authors.initials: A
authors.lastname: Nanci
mesh_terms: D000565:Ameloblasts / Q000166:cytology / Q000378:metabolism; D000818:Animals; D001861:Bone Regeneration; D016723:Bone Remodeling; D002113:Calcification, Physiologic; D003746:Dental Enamel Proteins / Q000502:physiology*; D051379:Mice; D008817:Mice, Mutant Strains; D013977:Tibia / Q000293:injuries; D014945:Wound Healing
chemical_list: C490890:Ambn protein, mouse; D003746:Dental Enamel Proteins; C109069:enamel matrix proteins