CSF-1 regulation of osteoclastogenesis for tooth eruption
Department of Cell Biology
Medical Subject Headings
Animals; Dental Sac; Down-Regulation; Gene Expression Regulation, Developmental; Glycoproteins; Immunoenzyme Techniques; Macrophage Colony-Stimulating Factor; Osteoclasts; Osteoprotegerin; RNA, Small Interfering; Rats; Rats, Mutant Strains; Receptors, Cytoplasmic and Nuclear; Receptors, Tumor Necrosis Factor; Reverse Transcriptase Polymerase Chain Reaction; Tooth Eruption; Transfection
The dental follicle regulates the alveolar bone resorption needed for tooth eruption. In the rat first mandibular molar, a decrease in the expression of osteoprotegerin (OPG) in the dental follicle at day 3 enables the osteoclastogenesis needed for eruption to occur. Because colony-stimulating factor-1 (CSF-1) is maximally expressed in the dental follicle at day 3, it was hypothesized that CSF-1 down-regulates OPG gene expression in the dental follicle in vivo. To test this, we compared the expression of OPG in osteopetrotic toothless (tl/tl) rats deficient in CSF-1 with expression in their normal littermates for given ages. OPG gene expression was found to be higher in the dental follicle of the tl/tl mutants than in normals. Transfecting short interfering RNA specific for CSF-1 mRNA into dental follicle cells resulted in an up-regulation of OPG expression. Thus, these studies support our hypothesis that the down-regulation of OPG needed for tooth eruption is mediated by CSF-1.
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Citation: J Dent Res. 2005 Sep;84(9):837-41.