title: Bovine dentine organic matrix down-regulates osteoclast activity.
abstract: Physiological root resorption is a phenomenon that normally takes place in deciduous teeth; root resorption of permanent teeth occurs only under pathological conditions. The molecular mechanisms underlying these processes are still unclear. Our previous study showed that osteoclasts cultured on deciduous dentine exhibited a higher degree of resorption and higher levels of cathepsin K and MMP-9 mRNA than osteoclasts cultured on permanent dentine. These results could be because of different susceptibilities to acid and the different organic matrices between deciduous and permanent dentine. Thus, the purpose of this study was to investigate the effect of dentine extracts from bovine deciduous and permanent dentine on osteoclast activity. Osteoclasts, obtained from mouse bone marrow cells co-cultured with an osteoblast-rich fraction in the presence of 1,25-(OH)(2)-vitamin D3 and PGE2, were incubated with or without 0.6 M HCl extracts from bovine deciduous or permanent dentine for 48 h. TRAP positive cell number, TRAP activity, the areas of resorption pits, and mRNA levels of TRAP, v-ATPase, calcitonin receptor, cathepsin K, and MMP-9 were examined. The results illustrated that TRAP activity, the resorbed area, and the mRNA levels of osteoclast marker genes seemed to be suppressed by both deciduous and permanent dentine extracts. These findings indicate that some factors that suppress osteoclast activity are contained in both deciduous and permanent dentine extracts. Although there was no significant difference in osteoclast activity between deciduous and permanent dentine extracts, osteoclasts incubated with permanent dentine extracts tend to exhibit less resorption activity than those incubated with deciduous dentine extracts. However, we could not clearly explain the causes of this.
authors.affiliation: Section of Developmental Oral Health Science, Department of Orofacial Development and Function, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Wantida
authors.initials: W
authors.lastname: Sriarj
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Aoki
authors.forename: Keiichi
authors.initials: K
authors.lastname: Ohya
authors.forename: Yuzo
authors.initials: Y
authors.lastname: Takagi
authors.forename: Hitoyata
authors.initials: H
authors.lastname: Shimokawa
mesh_terms: D000135:Acid Phosphatase / Q000378:metabolism; D000818:Animals; D001862:Bone Resorption / Q000378:metabolism; D002417:Cattle; D002452:Cell Count; D002454:Cell Differentiation / Q000187:drug effects; D018920:Coculture Techniques; D003804:Dentin / Q000378:metabolism*; D015536:Down-Regulation / Q000187:drug effects; D004591:Electrophoresis, Polyacrylamide Gel; D005109:Extracellular Matrix / Q000187:drug effects / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism; D051379:Mice; D010010:Osteoclasts / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D000071681:Tartrate-Resistant Acid Phosphatase; D014020:Tissue Extracts / Q000494:pharmacology; D019061:src-Family Kinases / Q000037:antagonists & inhibitors
chemical_list: D007527:Isoenzymes; D012333:RNA, Messenger; D014020:Tissue Extracts; D019061:src-Family Kinases; D000135:Acid Phosphatase; C000605511:Acp5 protein, mouse; D000071681:Tartrate-Resistant Acid Phosphatase