A tracer study with systemically and locally administered dinitrophenylated osteopontin.
Osteopontin (OPN), a major non-collagenous matrix protein of bone, is also found in tissue fluids and in the circulation. It is still not clear whether circulating OPN contributes to bone formation. To elucidate this question, rat OPN was tagged with dinitrophenol groups and administered to rats either intravenously or by infusion with an osmotic minipump through a "surgical window" in the bone of the hemimandible. Dinitrophenylated rat albumin (ALB) was used as a control. The presence and distribution of tagged proteins were revealed by immunogold labeling on sections of tibia and alveolar bone. Tagged molecules of OPN were found in mineralization foci, surfaces and interfaces, and matrix accumulations among calcified collagen fibrils. Even though dinitrophenylated ALB was administered at several-fold higher concentrations, it did not accumulate in these sites. These results show that circulating OPN can be incorporated into specific compartments of forming bone and suggest that such molecules may play a more important role than previously suspected.
Nanci
Antonio
A
Laboratory for the Study of Calcified Tissues and Biomaterials, Faculty of Dentistry, Université de Montréal, PO Box 6128, Station Centre-Ville, Montreal, QC, Canada H3C 3J7. antonio.nanci@umontreal.ca
Wazen
Rima M
RM
Zalzal
Sylvia F
SF
Fortin
Micheline
M
Goldberg
Harvey A
HA
Hunter
Graeme K
GK
Ghitescu
Dorin-Lucian
DL
D000818:Animals; D004140:Dinitrophenols / Q000737:chemistry*; D007150:Immunohistochemistry; D007260:Infusion Pumps; D017148:Infusions, Intraosseous; D007275:Injections, Intravenous; D008297:Male; D008334:Mandible / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D009928:Organ Specificity; D010012:Osteogenesis / Q000187:drug effects / Q000502:physiology*; D053495:Osteopontin; D051381:Rats; D017208:Rats, Wistar; D012795:Sialoglycoproteins / Q000008:administration & dosage / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D013977:Tibia / Q000378:metabolism / Q000502:physiology; D013997:Time Factors
D004140:Dinitrophenols; D012795:Sialoglycoproteins; C506897:Spp1 protein, rat; D053495:Osteopontin