title: Tracking endogenous amelogenin and ameloblastin in vivo.
abstract: Research on enamel matrix proteins (EMPs) is centered on understanding their role in enamel biomineralization and their bioactivity for tissue engineering. While therapeutic application of EMPs has been widely documented, their expression and biological function in non-enamel tissues is unclear. Our first aim was to screen for amelogenin (AMELX) and ameloblastin (AMBN) gene expression in mandibular bones and soft tissues isolated from adult mice (15 weeks old). Using RT-PCR, we showed mRNA expression of AMELX and AMBN in mandibular alveolar and basal bones and, at low levels, in several soft tissues; eyes and ovaries were RNA-positive for AMELX and eyes, tongues and testicles for AMBN. Moreover, in mandibular tissues AMELX and AMBN mRNA levels varied according to two parameters: 1) ontogenic stage (decreasing with age), and 2) tissue-type (e.g. higher level in dental epithelial cells and alveolar bone when compared to basal bone and dental mesenchymal cells in 1 week old mice). In situ hybridization and immunohistodetection were performed in mandibular tissues using AMELX KO mice as controls. We identified AMELX-producing (RNA-positive) cells lining the adjacent alveolar bone and AMBN and AMELX proteins in the microenvironment surrounding EMPs-producing cells. Western blotting of proteins extracted by non-dissociative means revealed that AMELX and AMBN are not exclusive to mineralized matrix; they are present to some degree in a solubilized state in mandibular bone and presumably have some capacity to diffuse. Our data support the notion that AMELX and AMBN may function as growth factor-like molecules solubilized in the aqueous microenvironment. In jaws, they might play some role in bone physiology through autocrine/paracrine pathways, particularly during development and stress-induced remodeling.
authors.affiliation: Laboratory of Molecular Oral Pathophysiology, INSERM UMRS 1138, Team Berdal, Cordeliers Research Center, Pierre and Marie Curie University - Paris 6, Paris Descartes University - Paris 5, Paris, France; UFR d'Odontologie, Paris Diderot University - Paris 7, Paris, France; Unit of Periodontology, Department of Stomatology, University of Talca, Talca, Chile.
authors.forename: Jaime
authors.initials: J
authors.lastname: Jacques
authors.affiliation: Laboratory of Molecular Oral Pathophysiology, INSERM UMRS 1138, Team Berdal, Cordeliers Research Center, Pierre and Marie Curie University - Paris 6, Paris Descartes University - Paris 5, Paris, France.
authors.forename: Dominique
authors.initials: D
authors.lastname: Hotton
authors.affiliation: Laboratory of Molecular Oral Pathophysiology, INSERM UMRS 1138, Team Berdal, Cordeliers Research Center, Pierre and Marie Curie University - Paris 6, Paris Descartes University - Paris 5, Paris, France; UFR d'Odontologie, Paris Diderot University - Paris 7, Paris, France; Center of Rare Malformations of the Face and Oral Cavity (MAFACE), Hospital Rothschild, AP-HP, Paris, France.
authors.forename: Muriel
authors.initials: M
authors.lastname: De la Dure-Molla
authors.affiliation: Laboratory of Molecular Oral Pathophysiology, INSERM UMRS 1138, Team Berdal, Cordeliers Research Center, Pierre and Marie Curie University - Paris 6, Paris Descartes University - Paris 5, Paris, France.
authors.forename: Stephane
authors.initials: S
authors.lastname: Petit
authors.affiliation: Laboratory of Molecular Oral Pathophysiology, INSERM UMRS 1138, Team Berdal, Cordeliers Research Center, Pierre and Marie Curie University - Paris 6, Paris Descartes University - Paris 5, Paris, France.
authors.forename: Audrey
authors.initials: A
authors.lastname: Asselin
authors.affiliation: Functional Genomics Section, Laboratory of Cell and Developmental Biology, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland, United States of America.
authors.forename: Ashok B
authors.initials: AB
authors.lastname: Kulkarni
authors.affiliation: Department of Anatomy and Cell Biology, University of Pennsylvania School of Dental Medicine, Philadelphia, Pennsylvania, United States of America.
authors.forename: Carolyn Winters
authors.initials: CW
authors.lastname: Gibson
authors.affiliation: Department of Oral Biology, School of Dentistry, University of Leeds, United Kingdom.
authors.forename: Steven Joseph
authors.initials: SJ
authors.lastname: Brookes
authors.affiliation: Laboratory of Molecular Oral Pathophysiology, INSERM UMRS 1138, Team Berdal, Cordeliers Research Center, Pierre and Marie Curie University - Paris 6, Paris Descartes University - Paris 5, Paris, France; UFR d'Odontologie, Paris Diderot University - Paris 7, Paris, France; Center of Rare Malformations of the Face and Oral Cavity (MAFACE), Hospital Rothschild, AP-HP, Paris, France.
authors.forename: Ariane
authors.initials: A
authors.lastname: Berdal
authors.affiliation: Laboratory of Molecular Oral Pathophysiology, INSERM UMRS 1138, Team Berdal, Cordeliers Research Center, Pierre and Marie Curie University - Paris 6, Paris Descartes University - Paris 5, Paris, France; Laboratory of Morphogenesis Molecular Genetics, Department of Developmental and Stem Cells Biology, Institut Pasteur, CNRS URA 2578, Paris, France.
authors.forename: Juliane
authors.initials: J
authors.lastname: Isaac
mesh_terms: D053523:Amelogenin / Q000032:analysis / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D000818:Animals; D003746:Dental Enamel Proteins / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D004058:Diffusion; D004847:Epithelial Cells / Q000378:metabolism; D005136:Eye Proteins / Q000032:analysis / Q000502:physiology; D005260:Female; D018507:Gene Expression Regulation, Developmental; D008297:Male; D008334:Mandible / Q000254:growth & development / Q000378:metabolism*; D008648:Mesoderm / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D009124:Muscle Proteins / Q000032:analysis / Q000502:physiology; D009928:Organ Specificity; D010053:Ovary / Q000254:growth & development / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis; D012995:Solubility; D013737:Testis / Q000254:growth & development / Q000378:metabolism; D014059:Tongue / Q000254:growth & development / Q000378:metabolism; D014781:Viscera / Q000254:growth & development / Q000378:metabolism
chemical_list: C490890:Ambn protein, mouse; D053523:Amelogenin; D003746:Dental Enamel Proteins; D005136:Eye Proteins; D009124:Muscle Proteins; D012333:RNA, Messenger