title: Chronology and regulation of gene expression of RANKL in the rat dental follicle.
abstract: Tooth eruption in the rat requires bone resorption resulting from a major burst of osteoclastogenesis on postnatal day 3 and a minor burst of osteoclastogenesis on postnatal day 10 in the alveolar bone of the first mandibular molar. The dental follicle regulates the major burst on postnatal day 3 by down-regulating its osteoprotegerin (OPG) gene expression to enable osteoclastogenesis to occur. To determine the role of receptor activator of nuclear factor-kappa B ligand (RANKL) in tooth eruption, its gene expression was measured on postnatal days 1-11 in the dental follicle. The results show that RANKL expression was significantly elevated on postnatal days 9-11 in comparison to low expression levels at earlier time-points. As OPG expression is high at this latter time-point, this increase in RANKL expression would be needed for stimulating the minor burst of osteoclastogenesis. Tumor necrosis factor-alpha enhances RANKL gene expression in vitro and it may be responsible for up-regulating RANKL in vivo. Transforming growth factor-beta1 and interleukin-1alpha also enhance RANKL gene expression in vitro but probably have no effect in vivo because they are maximally expressed early. Bone morphogenetic protein-2 acts to down-regulate RANKL expression in vitro and, in vivo, may promote alveolar bone growth in the basal region of the tooth.
authors.affiliation: Department of Comparative Biomedical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803, USA.
authors.forename: D
authors.initials: D
authors.lastname: Liu
authors.forename: S
authors.initials: S
authors.lastname: Yao
authors.forename: F
authors.initials: F
authors.lastname: Pan
authors.forename: G E
authors.initials: GE
authors.lastname: Wise
mesh_terms: D000539:Alveolar Process / Q000187:drug effects / Q000254:growth & development; D000818:Animals; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000494:pharmacology; D002352:Carrier Proteins / Q000032:analysis* / Q000187:drug effects / Q000235:genetics; D003795:Dental Sac / Q000166:cytology / Q000378:metabolism*; D015536:Down-Regulation; D005786:Gene Expression Regulation / Q000235:genetics; D006023:Glycoproteins / Q000032:analysis / Q000235:genetics; D007375:Interleukin-1 / Q000494:pharmacology; D008562:Membrane Glycoproteins / Q000032:analysis* / Q000187:drug effects / Q000235:genetics; D010010:Osteoclasts / Q000502:physiology; D010012:Osteogenesis / Q000235:genetics / Q000502:physiology; D053244:Osteoprotegerin; D053245:RANK Ligand; D051381:Rats; D018160:Receptors, Cytoplasmic and Nuclear / Q000032:analysis / Q000235:genetics; D018124:Receptors, Tumor Necrosis Factor / Q000032:analysis / Q000235:genetics; D013997:Time Factors; D014078:Tooth Eruption / Q000235:genetics / Q000502:physiology; D016212:Transforming Growth Factor beta / Q000494:pharmacology; D053773:Transforming Growth Factor beta1; D047988:Tumor Necrosis Factor Receptor-Associated Peptides and Proteins / Q000032:analysis* / Q000235:genetics; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis* / Q000235:genetics / Q000494:pharmacology; D015854:Up-Regulation
chemical_list: C525720:Bmp2 protein, rat; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D002352:Carrier Proteins; D006023:Glycoproteins; D007375:Interleukin-1; D008562:Membrane Glycoproteins; D053244:Osteoprotegerin; D053245:RANK Ligand; D018160:Receptors, Cytoplasmic and Nuclear; D018124:Receptors, Tumor Necrosis Factor; C508962:Tgfb1 protein, rat; C506032:Tnfrsf11b protein, rat; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D047988:Tumor Necrosis Factor Receptor-Associated Peptides and Proteins; D014409:Tumor Necrosis Factor-alpha