| 1591 C-Type Natriuretic Peptide Differential Regulation of Matrix Proteins in Ameloblasts and Odontoblasts | ||
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J. SCHULZE, M. STEINHELPER, P. PAPAGERAKIS, and M. MACDOUGALL, University of Texas Health Science Center at San Antonio, USA C-type natriuretic peptide (CNP) belongs to a family of hormones involved in regulation of blood pressure, extracellular fluid, and ion homeostasis. Inactivation of the mouse Nppc gene encoding CNP results in an autosomal recessive form of amelogenesis imperfecta. Objective: To study in vitro the effects of CNP on tooth protein expression and mineralization. Methods: Immortalized mouse odontoblast (MO6-G3) and ameloblast (MEOE-3M) cells were plated in 6 well plates. After 24 hrs for cell attachment, media was changed and supplemented with or without 10-7 M CNP. Cultures were maintained for 6 days with samples harvested at day 3 or 6 for in situ alkaline phosphatase (ALP) histochemistry, vonKossa staining, and RT-PCR analysis of major tooth matrix transcripts. Results: Moderate ALP expression of the MEOE-3M cells by 6 days was slightly decreased by CNP treatment in contrast to vonVossa staining that was augmented. In MO6-G3 cells intense ALP staining and vonKossa staining was enhanced by CNP treatment. Tooth matrix transcripts in the MEOE-3M cells associated with the secretory stage of amelogenesis, amelogenin (Amg), dentin sialophosphoprotein (DSPP), and enamelin (Enam), were significantly up-regulated by CNP. In contrast, the enamel proteinase EMSP1, expressed at high levels at the maturation stage, was significantly down-regulated by CNP treatment. In odontoblasts, addition of CNP had an opposite affect dramatically down-regulating DSPP, EMSP-1, and Enam, with a less severe decrease in Amg transcripts. Conclusions: CNP differential regulates the expression of tooth matrix proteins in epithelial-derived ameloblasts versus mesenchymal-derived odontoblasts. CNP promotes tooth matrix protein expression in ameloblasts, augmenting mineralization. This data suggests the dental phenotype of Nppc null mice results in aberrant expression of critical matrix proteins resulting from a lack of CNP. Therefore, CNP is an essential factor for normal tooth matrix gene expression associated with amelogenesis. Support : Human Growth Foundation (MS) and NIDCR DE09875 (MM). | ||
| Seq #201 - Senior Category 11:00 AM-12:15 PM, Saturday, 15 March 2003 Henry B. Gonzalez Convention Center Exhibit Hall C | ||
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