In some inherited disorders of the skeleton, including osteopetrosis and osteosclerosis, excess bone accumulates whereas in osteoporosis bone loss significantly exceeds bone gain. Historically, bone formation was associated with the osteoblast and resorption with the osteoclast. However, data has accumulated which indicates that the osteoblast takes an active role in the resorption process. This cell has been shown to be the primary target for a variety of resorption process. This cell has been shown to be the primary target for a variety of resorption agents (e.g., parathyroid hormone, PTH, and 1, 25(OH)2D3) and to be capable of producing neutral proteases, such as plasminogen activator and collagenase (C'ase). We have recently shown that PTH stimulates secretion of the latter enzyme by the rat osteoblastic cell line, UMR 106-01, with maximal concentrations of C'ase appearing in the extracellular medium 12-24 h after addition of the hormone. These subsequently decline becoming almost undetectable by 96 h. Further experiments revealed that the disappearance of previously secreted enzyme was cell-mediated and suggested the action of a membrane receptor for C'ase. We have now demonstrated the existence of such a receptor on UMR cells which may be analogous to those reported for serine proteases. These appear to be responsible for either activation and/or endocytosis of the secreted enzyme. This has led us to formulate the hypothesis that the C'ase receptor on osteoblastic cells is involved in the regulation of the amounts of extracellular bone C'ase and that down- regulation of such a moiety (e.g., by treatment of cells with PTH) may dictate the abundance and function of the enzyme in the extracellular milieu. Thus, the aims of the present proposal are to further characterize the receptor and to test this hypothesis.
These aims will be accomplished by: 1) delineating the characteristics of the binding reaction, including determining whether receptor number or affinity changes after PTH treatment, 2) assessing the role of the receptor in the cell-mediated turnover of the ligand, C'ase, and whether an alteration in the receptor modifies this process, 3) determining the biochemical properties of the receptor, both by cross-linking 125I-labelled C'ase to the receptor and by 125I-labelling the receptor, and finally, 4) using this information and techniques to purify the receptor and obtain peptide sequence data. The results of this work should aid in ascertaining the multiple sites of regulation in the osteoblast of elaborated C'ase and shed some light on the comprehensive role of this cell in the remodelling process (both matrix synthesis and degradation). In so doing, the data should also provide some insight into those many skeletal disorders where bone remodelling (? aberrant C'ase expression/uptake) has gone awry.

Agency
National Institute of Health (NIH)
Institute
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Type
Research Project (R01)
Project #
5R01AR040661-02
Application #
3161092
Study Section
Orthopedics and Musculoskeletal Study Section (ORTH)
Project Start
1991-02-01
Project End
1995-01-31
Budget Start
1992-02-01
Budget End
1993-01-31
Support Year
2
Fiscal Year
1992
Total Cost
Indirect Cost
Name
Saint Louis University
Department
Type
Schools of Medicine
DUNS #
City
Saint Louis
State
MO
Country
United States
Zip Code
63103
Raggatt, L J; Jefcoat Jr, S C; Choudhury, I et al. (2006) Matrix metalloproteinase-13 influences ERK signalling in articular rabbit chondrocytes. Osteoarthritis Cartilage 14:680-9
Walling, H W; Raggatt, L J; Irvine, D W et al. (2003) Impairment of the collagenase-3 endocytotic receptor system in cells from patients with osteoarthritis. Osteoarthritis Cartilage 11:854-63
Partridge, N C; Fiacco, G J; Walling, H W et al. (2000) Effects of dioxin and estrogen on collagenase-3 in UMR 106-01 osteosarcoma cells. Arch Biochem Biophys 382:182-8
Barmina, O Y; Walling, H W; Fiacco, G J et al. (1999) Collagenase-3 binds to a specific receptor and requires the low density lipoprotein receptor-related protein for internalization. J Biol Chem 274:30087-93
Walling, H W; Chan, P T; Omura, T H et al. (1998) Regulation of the collagenase-3 receptor and its role in intracellular ligand processing in rat osteoblastic cells. J Cell Physiol 177:563-74
Partridge, N C; Walling, H W; Bloch, S R et al. (1996) The regulation and regulatory role of collagenase in bone. Crit Rev Eukaryot Gene Expr 6:15-27
Connolly, T J; Clohisy, J C; Shilt, J S et al. (1994) Retinoic acid stimulates interstitial collagenase messenger ribonucleic acid in osteosarcoma cells. Endocrinology 135:2542-8
Omura, T H; Noguchi, A; Johanns, C A et al. (1994) Identification of a specific receptor for interstitial collagenase on osteoblastic cells. J Biol Chem 269:24994-8
Clohisy, J C; Connolly, T J; Bergman, K D et al. (1994) Prostanoid-induced expression of matrix metalloproteinase-1 messenger ribonucleic acid in rat osteosarcoma cells. Endocrinology 135:1447-54
Cook, T F; Burke, J S; Bergman, K D et al. (1994) Cloning and regulation of rat tissue inhibitor of metalloproteinases-2 in osteoblastic cells. Arch Biochem Biophys 311:313-20

Showing the most recent 10 out of 11 publications