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Secreted frizzled-related protein-1 inhibits RANKL-dependent osteoclast formation.
J Bone Miner Res. 2004 Nov; 19(11):1873-81.JB

Abstract

We determined that sFRP-1 mRNA was differentially expressed by osteoblast/stromal cell lines and that sFRP-1 neutralizing antibodies and siRNA complementary to sFRP-1 coding sequence enhanced, while recombinant sFRP-1 inhibited, osteoclast formation. In studying the mechanism of action for sFRP-1, we found that sFRP-1 could bind recombinant RANKL. These results suggest potential cross-talk between Wnt and RANKL pathways.

INTRODUCTION

Osteoclast formation in normal bone remodeling requires the presence of osteoblast lineage cells that express RANKL and macrophage-colony-stimulating factor (M-CSF), which interact with their cognate receptors on the osteoclast precursor. We identified secreted Frizzled-related protein-1 (sFRP-1), which is known to bind to Wnt and inhibit the Wnt signaling pathway, as an osteoblast-derived factor that impinges on osteoclast formation and activity.

MATERIALS AND METHODS

Differential display of mRNA from osteoblast lineage cell lines established sFRP-1 to be highly expressed in an osteoclast supporting cell line. sFRP-1 expression in bone was determined by in situ hybridization, and the effects of sFRP-1 on osteoclast formation were determined using a neutralizing antibody, siRNA, for sFRP-1 and recombinant protein.

RESULTS

In situ hybridization revealed sFRP-1 mRNA expression in osteoblasts and chondrocytes in murine bone. sFRP-1 mRNA expression could be elevated in calvarial primary osteoblasts in response to prostaglandin E2 (PGE2) or interleukin (IL)-11, whereas many other osteotropic agents (e.g., IL-1, IL-6, calcitrol, parathyroid hormone) were without any effect. In vitro assays of osteoclast formation established sFRP-1 to be an inhibitor of osteoclast formation. Neutralizing antibodies against sFRP-1 enhanced TRACP+ mononuclear and multinuclear osteoclast formation (3- and 2-fold, respectively) in co-cultures of murine osteoblasts with spleen cells, whereas siRNA complementary to sFRP-1 coding sequence significantly enhanced osteoclast formation in co-cultures of KUSA O (osteoblast/stromal cell line) and bone marrow cells, cultured in the presence of PGE2 and 1,25(OH)2 vitamin D3. Recombinant sFRP-1 dose-dependently inhibited osteoclast formation in osteoblast/spleen co-cultures, RANKL + M-CSF-treated splenic cultures, and RANKL-treated RAW264.7 cell cultures, indicating a direct action of sFRP-1 on hematopoietic cells. Consistent with this, sFRP-1 was found to bind to RANKL in ELISAs.

CONCLUSION

sFRP-1 is expressed by osteoblasts and inhibits osteoclast formation. While sFRP-1 activity might involve the blocking of endogenous Wnt signaling, our results suggest that, alternatively, it could be because of direct binding to RANKL. This study describes a new mechanism whereby osteoblasts regulate osteoclastogenesis through the expression and release of sFRP-1.

Authors+Show Affiliations

Bone, Joint, and Cancer Unit, St Vincent's Institute of Medical Research, Fitzroy, Victoria, Australia.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

15476588

Citation

Häusler, Karl D., et al. "Secreted Frizzled-related Protein-1 Inhibits RANKL-dependent Osteoclast Formation." Journal of Bone and Mineral Research : the Official Journal of the American Society for Bone and Mineral Research, vol. 19, no. 11, 2004, pp. 1873-81.
Häusler KD, Horwood NJ, Chuman Y, et al. Secreted frizzled-related protein-1 inhibits RANKL-dependent osteoclast formation. J Bone Miner Res. 2004;19(11):1873-81.
Häusler, K. D., Horwood, N. J., Chuman, Y., Fisher, J. L., Ellis, J., Martin, T. J., Rubin, J. S., & Gillespie, M. T. (2004). Secreted frizzled-related protein-1 inhibits RANKL-dependent osteoclast formation. Journal of Bone and Mineral Research : the Official Journal of the American Society for Bone and Mineral Research, 19(11), 1873-81.
Häusler KD, et al. Secreted Frizzled-related Protein-1 Inhibits RANKL-dependent Osteoclast Formation. J Bone Miner Res. 2004;19(11):1873-81. PubMed PMID: 15476588.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Secreted frizzled-related protein-1 inhibits RANKL-dependent osteoclast formation. AU - Häusler,Karl D, AU - Horwood,Nicole J, AU - Chuman,Yoshiro, AU - Fisher,Jane L, AU - Ellis,Jennifer, AU - Martin,T John, AU - Rubin,Jeffrey S, AU - Gillespie,Matthew T, Y1 - 2004/08/16/ PY - 2003/10/11/received PY - 2004/04/06/revised PY - 2004/05/27/accepted PY - 2004/10/13/pubmed PY - 2005/3/25/medline PY - 2004/10/13/entrez SP - 1873 EP - 81 JF - Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research JO - J Bone Miner Res VL - 19 IS - 11 N2 - UNLABELLED: We determined that sFRP-1 mRNA was differentially expressed by osteoblast/stromal cell lines and that sFRP-1 neutralizing antibodies and siRNA complementary to sFRP-1 coding sequence enhanced, while recombinant sFRP-1 inhibited, osteoclast formation. In studying the mechanism of action for sFRP-1, we found that sFRP-1 could bind recombinant RANKL. These results suggest potential cross-talk between Wnt and RANKL pathways. INTRODUCTION: Osteoclast formation in normal bone remodeling requires the presence of osteoblast lineage cells that express RANKL and macrophage-colony-stimulating factor (M-CSF), which interact with their cognate receptors on the osteoclast precursor. We identified secreted Frizzled-related protein-1 (sFRP-1), which is known to bind to Wnt and inhibit the Wnt signaling pathway, as an osteoblast-derived factor that impinges on osteoclast formation and activity. MATERIALS AND METHODS: Differential display of mRNA from osteoblast lineage cell lines established sFRP-1 to be highly expressed in an osteoclast supporting cell line. sFRP-1 expression in bone was determined by in situ hybridization, and the effects of sFRP-1 on osteoclast formation were determined using a neutralizing antibody, siRNA, for sFRP-1 and recombinant protein. RESULTS: In situ hybridization revealed sFRP-1 mRNA expression in osteoblasts and chondrocytes in murine bone. sFRP-1 mRNA expression could be elevated in calvarial primary osteoblasts in response to prostaglandin E2 (PGE2) or interleukin (IL)-11, whereas many other osteotropic agents (e.g., IL-1, IL-6, calcitrol, parathyroid hormone) were without any effect. In vitro assays of osteoclast formation established sFRP-1 to be an inhibitor of osteoclast formation. Neutralizing antibodies against sFRP-1 enhanced TRACP+ mononuclear and multinuclear osteoclast formation (3- and 2-fold, respectively) in co-cultures of murine osteoblasts with spleen cells, whereas siRNA complementary to sFRP-1 coding sequence significantly enhanced osteoclast formation in co-cultures of KUSA O (osteoblast/stromal cell line) and bone marrow cells, cultured in the presence of PGE2 and 1,25(OH)2 vitamin D3. Recombinant sFRP-1 dose-dependently inhibited osteoclast formation in osteoblast/spleen co-cultures, RANKL + M-CSF-treated splenic cultures, and RANKL-treated RAW264.7 cell cultures, indicating a direct action of sFRP-1 on hematopoietic cells. Consistent with this, sFRP-1 was found to bind to RANKL in ELISAs. CONCLUSION: sFRP-1 is expressed by osteoblasts and inhibits osteoclast formation. While sFRP-1 activity might involve the blocking of endogenous Wnt signaling, our results suggest that, alternatively, it could be because of direct binding to RANKL. This study describes a new mechanism whereby osteoblasts regulate osteoclastogenesis through the expression and release of sFRP-1. SN - 0884-0431 UR - https://www.unboundmedicine.com/medline/citation/15476588/Secreted_frizzled_related_protein_1_inhibits_RANKL_dependent_osteoclast_formation_ L2 - https://doi.org/10.1359/JBMR.040807 DB - PRIME DP - Unbound Medicine ER -