The effect of LRAP on enamel organ epithelial cell differentiation.
Leucine-rich amelogenin peptide (LRAP) is an alternatively spliced amelogenin found in the developing enamel organ. LRAP functions to regulate the development of mesenchymal-derived cells; however, its effect on cells of the enamel organ remains unclear. The hypothesis tested in this study is that LRAP also regulates human enamel organ epithelial cells. Recombinant human LRAP (rH58) was synthesized in E. coli, purified, and exogenously added to cultures of human primary enamel epithelial cells, which were analyzed for changes in cell proliferation and differentiation. rH58 had no effect on cell proliferation, but altered enamel epithelial cell morphology, resulting in larger, more rounded cells. Immunofluorescence showed that rH58 treatment increased amelogenin synthesis, but down-regulated Notch1 expression in enamel epithelial cells. LAMP-1, a membrane receptor for LRAP in mesenchymal cells, was identified and was up-regulated in the presence of rH58. These results suggest that rH58 promotes differentiation of human enamel organ epithelial cells.
Le
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Department of Orofacial Sciences, University of California at San Francisco, 513 Parnassus Avenue, PO Box #0422; San Francisco, CA 94143-0422, USA. Thuan.Le@ucsf.edu
Zhang
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Li
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Denbesten
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D000566:Amelogenesis / Q000502:physiology*; D053523:Amelogenin / Q000096:biosynthesis; D002454:Cell Differentiation; D049109:Cell Proliferation; D048430:Cell Shape; D048429:Cell Size; D003746:Dental Enamel Proteins / Q000494:pharmacology / Q000502:physiology*; D004658:Enamel Organ / Q000166:cytology*; D004847:Epithelial Cells / Q000166:cytology*; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D051907:Lysosomal Membrane Proteins / Q000096:biosynthesis; D051881:Receptor, Notch1 / Q000096:biosynthesis; D011994:Recombinant Proteins; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015854:Up-Regulation; D052118:Lysosomal-Associated Membrane Protein 1
D053523:Amelogenin; D003746:Dental Enamel Proteins; D051907:Lysosomal Membrane Proteins; D051881:Receptor, Notch1; D011994:Recombinant Proteins; C489116:LAMP1 protein, human; D052118:Lysosomal-Associated Membrane Protein 1; C497761:NOTCH1 protein, human; C067432:leucine-rich amelogenin peptide