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Expression of bone sialoprotein mRNA during bone formation and resorption induced by colchicine in rat tibial bone marrow cavity
Author(s) -
Arai N.,
Ohya K.,
Kasugai S.,
Shimokawa H.,
Ohida S.,
Ogura H.,
Amagasa T.
Publication year - 1995
Publication title -
journal of bone and mineral research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.882
H-Index - 241
eISSN - 1523-4681
pISSN - 0884-0431
DOI - 10.1002/jbmr.5650100811
Subject(s) - bone sialoprotein , osteopontin , bone resorption , bone marrow , chemistry , medullary cavity , in situ hybridization , resorption , bone cell , osteoid , bone healing , stromal cell , osteoclast , type i collagen , endocrinology , pathology , anatomy , biology , messenger rna , osteocalcin , alkaline phosphatase , medicine , biochemistry , in vitro , gene , enzyme
Abstract In the rat tibial bone marrow cavity, following colchicine injection, there is a phase of osteogenesis in which bone trabeculae replace the necrotic bone marrow tissues and fill the marrow cavity. The newly formed bone is subsequently resorbed by osteoclasts and normal bone marrow is restored. In this study, we correlated these morphologic events with the pattern of gene expression of bone sialoprotein (BSP), an extracellular matrix protein in mineralized tissues, to elucidate the possible functions of BSP in bone formation and resorption in vivo. The expressions of osteopontin (OPN) and type I collagen were also examined. Northern hybridization of the tibia demonstrated that OPN mRNA was gradually increased and expressed at a maximal level 10 days after colchicine injection (during the bone resorption process), while BSP mRNA expression already reached a maximal level at day 6 (during the initial process of bone formation). Its expression was, thus, quite temporary at the beginning of bone formation and different from that of type I collagen, which was continually elevated from days 6 to 10. In situ hybridization of the newly formed bone induced in the tibia revealed that BSP mRNA was evenly expressed in most osteoblasts and osteocytes, moreover in interconnecting colonies of spindle‐shaped cells, possibly preosteoblasts, at day 6. At day 10, however, its expression became restricted to some cells on the bone surfaces, some osteoblasts, and most osteoclasts. These observations suggest that BSP may play an important role mainly in the initiation of bone formation and is also associated with the functions of osteoclast in vivo.