Putative signaling action of amelogenin utilizes the Wnt/beta-catenin pathway.
OBJECTIVE
While it has long been known that amelogenin is essential for the proper development of enamel, its role has generally been seen as structural in nature. However, our new data implicate this protein in the regulation of cell signaling pathways in periodontal ligament cells and osteoblasts. In this article we report the successful purification of a recombinant mouse amelogenin protein and demonstrate that it has signaling activity in isolated mouse calvarial cells and human periodontal ligament cells.


METHODS
To determine the regulatory function of canonical Wnt signaling by amelogenin, we used TOPGAL transgenic mice. These mice express a beta-galactosidase transgene under the control of a LEF/TCF and beta-catenin-inducible promoter. To investigate in greater detail the molecular mechanisms involved in the beta-catenin signaling pathway, isolated osteoblasts and periodontal ligament cells were exposed to full-length recombinant mouse amelogenin and were evaluated for phenotypic changes and beta-catenin signaling using a TOPFLASH construct and the LacZ reporter gene.


RESULTS
In these in vitro models, we showed that amelogenin can activate beta-catenin signaling.


CONCLUSIONS
Using the TOPGAL transgenic mouse we showed that amelogenin expression in vivo is localized mainly around the root, the periodontal ligament and the alveolar bone.
Matsuzawa
M
M
Department of Orthopaedics, Center for Musculoskeletal Research, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA.
Sheu
T-J
TJ
Lee
Y-J
YJ
Chen
M
M
Li
T-F
TF
Huang
C T
CT
Holz
J D
JD
Puzas
J E
JE
D000539:Alveolar Process / Q000378:metabolism; D053523:Amelogenin / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D000818:Animals; D002478:Cells, Cultured; D015870:Gene Expression; D017930:Genes, Reporter; D006801:Humans; D051379:Mice; D008822:Mice, Transgenic; D010006:Osteoblasts / Q000378:metabolism*; D010513:Periodontal Ligament / Q000166:cytology / Q000378:metabolism*; D011994:Recombinant Proteins / Q000494:pharmacology; D015398:Signal Transduction / Q000502:physiology*; D051820:TCF Transcription Factors / Q000378:metabolism; D014092:Tooth Root / Q000378:metabolism; D014162:Transfection; D051153:Wnt Proteins / Q000378:metabolism*; D051176:beta Catenin / Q000096:biosynthesis / Q000378:metabolism*; D001616:beta-Galactosidase / Q000096:biosynthesis
D053523:Amelogenin; D011994:Recombinant Proteins; D051820:TCF Transcription Factors; D051153:Wnt Proteins; D051176:beta Catenin; D001616:beta-Galactosidase