The goal of this application is to characterize the role that the matrix metalloproteinase enamelysin (MMP-20) plays during dental enamel and tooth development. The enamel proteins (amelogenin, ameloblastin, enamelin) are cleaved soon after they are secreted into the enamel matrix. Enamelysin is expressed simultaneously with the enamel proteins and recombinant enamelysin will cleave recombinant amelogenin at virtually all of the precise sites previously observed in vivo. Thus, enamelysin is an important amelogenin processing enzyme. As for all MMPs, enamelysin contains a propeptide that must be cleaved if the enzyme is to become active. Enamelysin also has a hemopexin domain that is not functionally well defined. An enamelysin knockout (-/-) mouse was engineered to characterize the contribution of enamelysin to tooth and enamel development (Aim 1). The enamelysin -/-mouse is the only MMP -/- mouse with a profound phenotype that survives to breed. Thus, we can define the limits of the enamelysin promoter (Aim 2) so that it may be used to express an enamelysin transgene in the -/- background and revert the -/- phenotype back to normal. Furthermore, because the -/- mouse has a profound phenotype and can breed, we are in possession of the only MMP -/- mouse that can be utilized to characterize the mechanistic function of the MMP propeptide and/or hemopexin domain. So, we propose to introduce two enamelysin promoter transgenes into the -/-background. The first transgene will allow enamelysin to be secreted as an active enzyme (propeptide removed intracellularly) so that we may characterize the role of the enamelysin propeptide in tooth development (Aim 3). The second transgene will encode enamelysin without its' hemopexin domain so that the contribution of the hemopexin domain in tooth development may be characterized (Aim 4). The long-term goals of this project are to contribute to the understanding of enamel formation so that eventually synthetic enamel can be engineered for the repair of damaged (dental caries) or diseased (amelogenesis imperfecta) dental enamel. This application builds on results from a highly productive R29 grant (DE12098).

National Institute of Health (NIH)
National Institute of Dental & Craniofacial Research (NIDCR)
Research Project (R01)
Project #
Application #
Study Section
Oral Biology and Medicine Subcommittee 1 (OBM)
Program Officer
Small, Rochelle K
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Forsyth Institute
United States
Zip Code
Turk, Benjamin E; Lee, Daniel H; Yamakoshi, Yasuo et al. (2006) MMP-20 is predominately a tooth-specific enzyme with a deep catalytic pocket that hydrolyzes type V collagen. Biochemistry 45:3863-74
Beniash, Elia; Skobe, Ziedonis; Bartlett, John D (2006) Formation of the dentino-enamel interface in enamelysin (MMP-20)-deficient mouse incisors. Eur J Oral Sci 114 Suppl 1:24-9; discussion 39-41, 379
Bartlett, John D; Ganss, Bernhard; Goldberg, Michel et al. (2006) 3. Protein-protein interactions of the developing enamel matrix. Curr Top Dev Biol 74:57-115
Bartlett, J D; Ball, R L; Kawai, T et al. (2006) Origin, splicing, and expression of rodent amelogenin exon 8. J Dent Res 85:894-9
Bartlett, John D; Skobe, Ziedonis; Lee, Daniel H et al. (2006) A developmental comparison of matrix metalloproteinase-20 and amelogenin null mouse enamel. Eur J Oral Sci 114 Suppl 1:18-23; discussion 39-41, 379
Bartlett, J D; Dwyer, S E; Beniash, E et al. (2005) Fluorosis: a new model and new insights. J Dent Res 84:832-6
Kubota, Kaori; Lee, Daniel H; Tsuchiya, Masahiro et al. (2005) Fluoride induces endoplasmic reticulum stress in ameloblasts responsible for dental enamel formation. J Biol Chem 280:23194-202
Bartlett, J D; Beniash, E; Lee, D H et al. (2004) Decreased mineral content in MMP-20 null mouse enamel is prominent during the maturation stage. J Dent Res 83:909-13
Caterina, John J; Skobe, Ziedonis; Shi, Joanne et al. (2002) Enamelysin (matrix metalloproteinase 20)-deficient mice display an amelogenesis imperfecta phenotype. J Biol Chem 277:49598-604