Hedgehog Signaling in Mature Osteoblasts Regulates Bone Formation and Resorption by Controlling PTHrP and RANKL Expression
Open accessAbstract
Hedgehog (Hh) signaling is required for osteoblast differentiation from mesenchymal progenitors during endochondral bone formation. However, the role of Hh signaling in differentiated osteoblasts during adult bone homeostasis remains to be elucidated. We found that in the postnatal bone, Hh signaling activity was progressively reduced as osteoblasts mature. Upregulating Hh signaling selectively in mature osteoblasts led to increased bone formation and excessive bone resorption. As a consequence, these mutant mice showed severe osteopenia. Conversely, inhibition of Hh signaling in mature osteoblasts resulted in increased bone mass and protection from bone loss in older mice. Cellular and molecular studies showed that Hh signaling indirectly induced osteoclast differentiation by upregulating osteoblast expression of PTHrP, which promoted RANKL expression via PKA and its target transcription factor CREB. Our results demonstrate that Hh signaling in mature osteoblasts regulates both bone formation and resorption and that inhibition of Hh signaling reduces bone loss in aged mice.
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Hedgehog signaling is important for maintaining bone homeostasis in adult mice, with down-regulation of hedgehog signaling being protective against bone loss.
“In addition to the roles that IHH and SHH play in regulating bone development, hedgehog signaling is also important for maintaining bone homeostasis in adult mice, with down-regulation of hedgehog signaling being protective against bone loss (41, 42).”
From Targeting myostatin/activin A protects against skeletal muscle and bone loss during spaceflight (2020) · cites this paper as [41]
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Cites
Osteoprotegerin ligand is a cytokine that regulates osteoclast differentiation and activation.
Lacey, D. L., Timms, E., Tan, H.-L., Kelley, M. J., Dunstan, C. R., Burgess, T., Elliott, R., Colombero, A., Elliott, G., Scully, S., et al. (1998) · Cell · doi:10.1016/s0092-8674(00)81569-x · Cited by 5,439 · see citing works
Generalized lacZ expression with the ROSA26 Cre reporter strain
Soriano, P. (1999) · Nature Genetics · doi:10.1038/5007 · Cited by 5,237 · see citing works
Osteoprotegerin: a novel secreted protein involved in the regulation of bone density.
Simonet, W. S., Lacey, D. L., Dunstan, C. R., Kelley, M., Chang, M.-S., Lüthy, R., Nguyen, H. Q., Wooden, S., Bennett, L., Boone, T., et al. (1997) · Cell · doi:10.1016/s0092-8674(00)80209-3 · Cited by 5,130 · see citing works
PARFITT, A. M., Drezner, M. K., Glorieux, F. H., Kanis, J. А., Malluche, H. H., Meunier, P. J., Ott, S. M., & Recker, R. R. (1987) · Journal of Bone and Mineral Research · doi:10.1002/jbmr.5650020617 · Cited by 5,015 · see citing works
Yasuda, H., Shima, N., Nakagawa, N., Yamaguchi, K., Kinosaki, M., Mochizuki, S.-I., Tomoyasu, A., Yano, K., Goto, M., Murakami, A., et al. (1998) · Proceedings of the National Academy of Sciences · doi:10.1073/pnas.95.7.3597 · Cited by 4,224 · see citing works
Nakashima, K., Zhou, X., Kunkel, G., Zhang, Z., Deng, J. M., Behringer, R. R., & de Crombrugghe, B. (2002) · Cell · doi:10.1016/s0092-8674(01)00622-5 · Cited by 3,608 · see citing works
OPGL is a key regulator of osteoclastogenesis, lymphocyte development and lymph node organogenesis.
Kong, Y.-Y., Yoshida, H., Sarosi, I., Tan, H.-L., Timms, E., Capparelli, C., Morony, S., Oliveira-dos-Santos, A. J., Van, G., Itie, A., et al. (1999) · Nature · doi:10.1038/16852 · Cited by 3,351 · see citing works
Bone Histomorphometry : Standardization of Nomenclature, Symbols, and Units
PARFITT, A. M., Drezner, M. K., Glorieux, F. H., Kanis, J. А., Malluche, H. H., Meunier, P. J., Ott, S. M., & Recker, R. R. (1987) · Journal of Bone and Mineral Research · Cited by 3,258 · see citing works
Developmental regulation of the growth plate
Kronenberg, H. M. (2003) · Nature · doi:10.1038/nature01657 · Cited by 2,859 · see citing works
CREB: A Stimulus-Induced Transcription Factor Activated by A Diverse Array of Extracellular Signals
Shaywitz, A. J., & Greenberg, M. E. (1999) · Annual Review of Biochemistry · doi:10.1146/annurev.biochem.68.1.821 · Cited by 2,135 · see citing works
Regulation of Rate of Cartilage Differentiation by Indian Hedgehog and PTH-Related Protein
Vortkamp, A., Lee, K., Lanske, B., Segre, G. V., Kronenberg, H. M., & Tabin, C. J. (1996) · Science · doi:10.1126/science.273.5275.613 · Cited by 1,999 · see citing works
Human Homolog of patched , a Candidate Gene for the Basal Cell Nevus Syndrome
Johnson, R. L., Rothman, A., Xie, J., Goodrich, L. V., Bare, J. W., Bonifas, J. M., Quinn, A., Myers, R., Cox, D., Epstein, E. H., et al. (1996) · Science · doi:10.1126/science.272.5268.1668 · Cited by 1,856 · see citing works
St‐Jacques, B., Hammerschmidt, M., & McMahon, A. P. (1999) · Genes & Development · doi:10.1101/gad.13.16.2072 · Cited by 1,742 · see citing works
Altered Neural Cell Fates and Medulloblastoma in Mouse <i>patched</i> Mutants
Goodrich, L. V., Milenković, L., Higgins, K. M., & Scott, M. P. (1997) · Science · doi:10.1126/science.277.5329.1109 · Cited by 1,696 · see citing works
Reaching a Genetic and Molecular Understanding of Skeletal Development
Karsenty, G., & Wagner, E. F. (2002) · Developmental Cell · doi:10.1016/s1534-5807(02)00157-0 · Cited by 1,594 · see citing works
Canonical wnt signaling in differentiated osteoblasts controls osteoclast differentiation.
Glass, D. A., Bialek, P., Ahn, J. D., Starbuck, M., Patel, M. S., Clevers, H., Taketo, M. M., Long, F., McMahon, A. P., Lang, R. A., et al. (2005) · Developmental Cell · doi:10.1016/j.devcel.2005.02.017 · Cited by 1,558 · see citing works
Control of osteoblast function and regulation of bone mass
Harada, S.-I., & Rodan, G. A. (2003) · Nature · doi:10.1038/nature01660 · Cited by 1,451 · see citing works
Leptin regulation of bone resorption by the sympathetic nervous system and CART
Elefteriou, F., Ahn, J. D., Takeda, S., Starbuck, M., Yang, X., Liu, X., Kondo, H., Richards, W. G., Bannon, T. W., Noda, M., et al. (2005) · Nature · doi:10.1038/nature03398 · Cited by 1,311 · cited 4× · see citing works
“Since PTH can still activate RANKL expression in the ATF4 À/À osteoblasts (Elefteriou et al., 2005), we tested our hypothesis that PTHrP promotes RANKL expression by activating PKA and its target transcription factor CREB.”
BackgroundInfluentialA Parathyroid Hormone-Related Protein Implicated in Malignant Hypercalcemia: Cloning and Expression
Suva, L. J., Winslow, G. A., Wettenhall, R. E. H., Hammonds, R. G., Moseley, J. M., Diefenbach-Jagger, H., Rodda, C. P., Kemp, B. E., Rodriguez, H., Chen, E. Y., et al. (1987) · Science · doi:10.1126/science.3616618 · Cited by 1,292 · see citing works
A G Protein-Linked Receptor for Parathyroid Hormone and Parathyroid Hormone-Related Peptide
Jüppner, H., Abou‐Samra, A., Freeman, M. W., Kong, X. F., Schipani, E., Richards, J., Kolakowski, L. F., Hock, J. M., Potts, J. T. J., Kronenberg, H. M., et al. (1991) · Science · doi:10.1126/science.1658941 · Cited by 1,249 · see citing works
Rodda, S. J., & McMahon, A. P. (2006) · Development · doi:10.1242/dev.02480 · Cited by 1,011 · see citing works
Clinical Implications of the Osteoprotegerin/RANKL/RANK System for Bone and Vascular Diseases
Hofbauer, L. C. (2004) · JAMA · doi:10.1001/jama.292.4.490 · Cited by 979 · see citing works
Targeting the Hedgehog pathway in cancer
Rubin, L. L., & de Sauvage, F. J. (2006) · Nature Reviews Drug Discovery · doi:10.1038/nrd2086 · Cited by 951 · see citing works
Teratogen-Mediated Inhibition of Target Tissue Response to <i>Shh</i> Signaling
Cooper, M. K., Porter, J. A., Young, K. E., & Beachy, P. A. (1998) · Science · doi:10.1126/science.280.5369.1603 · Cited by 848 · see citing works
Goodrich, L. V., Johnson, R. L., Milenković, L., McMahon, J. A., & Scott, M. P. (1996) · Genes & Development · doi:10.1101/gad.10.3.301 · Cited by 825 · see citing works
Vertebrate Hedgehog signalling modulated by induction of a Hedgehog-binding protein
Chuang, P., & McMahon, A. P. (1999) · Nature · doi:10.1038/17611 · Cited by 798 · see citing works
Self-citationWnt-5a inhibits the canonical Wnt pathway by promoting GSK-3–independent β-catenin degradation
Topol, L. Z., Jiang, X., Choi, H., Garrett-Beal, L. J., Carolan, P. J., & Yang, Y. (2003) · The Journal of Cell Biology · doi:10.1083/jcb.200303158 · Cited by 724 · see citing works
Self-citationMolecular and cellular mechanisms of the anabolic effect of intermittent PTH
Jilka, R. L. (2007) · Bone · doi:10.1016/j.bone.2007.03.017 · Cited by 722 · see citing works
Basal Cell Carcinomas in Mice Overexpressing Sonic Hedgehog
Oro, A. E., Higgins, K. M., Hu, Z., Bonifas, J. M., Epstein, E. H., & Scott, M. P. (1997) · Science · doi:10.1126/science.276.5313.817 · Cited by 707 · see citing works
Zhang, M., Xuan, S., Bouxsein, M., Stechow, D. V., Akeno, N., Faugere, M.-C., Malluche, H. H., Zhao, G., Rosen, C. J., Efstratiadis, A., et al. (2002) · Journal of Biological Chemistry · doi:10.1074/jbc.m208265200 · Cited by 696 · see citing works
Self-citationBai, C. B., Auerbach, W., Lee, J. S., Stephen, D., & Joyner, A. L. (2002) · Development · doi:10.1242/dev.129.20.4753 · Cited by 692 · see citing works
Sequential roles of Hedgehog and Wnt signaling in osteoblast development
Hu, H., Hilton, M. J., Tu, X., Yu, K., Ornitz, D. M., & Long, F. (2005) · Development · doi:10.1242/dev.01564 · Cited by 682 · see citing works
Yasuda, H., Shima, N., Nakagawa, N., Yamaguchi, K., Kinosaki, M., Mochizuki, S.-I., Tomoyasu, A., Yano, K., Goto, M., Murakami, A., et al. (1998) · Cited by 650 · see citing works
Essential role of β-catenin in postnatal bone acquisition.
Holmen, S. L., Zylstra, C. R., Mukherjee, A., Sigler, R. E., Faugere, M.-C., Bouxsein, M. L., Deng, L., Clemens, T. L., & Williams, B. O. (2005) · Journal of Biological Chemistry · doi:10.1074/jbc.m501900200 · Cited by 584 · see citing works
Self-citationBreast Cancer Cells Interact with Osteoblasts to Support Osteoclast Formation1
Thomas, R. J., Guise, T. A., Yin, J. J., Elliott, J., Horwood, N. J., Martin, T. J., & Gillespie, M. T. (1999) · Endocrinology · doi:10.1210/endo.140.10.7037 · Cited by 536 · see citing works
Strewler, G. J., Stern, P. H., Jacobs, J., Eveloff, J., Klein, R. F., Leung, S. C., Rosenblatt, M., & Nissenson, R. A. (1987) · Journal of Clinical Investigation · doi:10.1172/jci113275 · Cited by 533 · see citing works
Huangfu, D., & Anderson, K. V. (2005) · Development · doi:10.1242/dev.02169 · Cited by 478 · see citing works
Wnt3a-/--like phenotype and limb deficiency in Lef1-/-Tcf1-/- micePreprint
Galcerán, J., Fariñas, I., Depew, M. J., Clevers, H. C., & Grosschedl, R. (1999) · Genes & Development · doi:10.1101/gad.13.6.709 · Cited by 462 · see citing works
Ma, Y. L., Cain, R. L., Halladay, D. L., Yang, X., Zeng, Q., Miles, R. R., Chandrasekhar, S., Martin, T. J., & Onyia, J. E. (2001) · Endocrinology · doi:10.1210/endo.142.9.8356 · Cited by 428 · see citing works
Parathyroid Hormone-Related Protein of Malignancy: Active Synthetic Fragments
Kemp, B. E., Moseley, J. M., Rodda, C. P., Ebeling, P. R., Wettenhall, R. E. H., Stapleton, D., Diefenbach-Jagger, H., Ure, F., Michelangeli, V. P., Simmons, H. A., et al. (1987) · Science · doi:10.1126/science.3685995 · Cited by 373 · see citing works
Kaneko, H., Arakawa, T., Mano, H., Kaneda, T., Ogasawara, A., Nakagawa, M., Toyama, Y., Yabe, Y., Kumegawa, M., & Hakeda, Y. (2000) · Bone · doi:10.1016/s8756-3282(00)00358-6 · Cited by 347 · see citing works
Osteoclasts derived from haematopoietic stem cells
Ash, P., Loutit, J. F., & Townsend, K. M. S. (1980) · Nature · doi:10.1038/283669a0 · Cited by 324 · see citing works
Protein kinase A signalling via CREB controls myogenesis induced by Wnt proteins
Chen, A. E., Ginty, D. D., & Fan, C.-M. (2005) · Nature · doi:10.1038/nature03126 · Cited by 309 · see citing works
Kim, N., Odgren, P. R., Kim, D., Marks, S. C., & Choi, Y. (2000) · Proceedings of the National Academy of Sciences · doi:10.1073/pnas.200294797 · Cited by 299 · see citing works
Barrow, J. R., Thomas, K. R., Boussadia, O., Moore, R. H., Kemler, R., Capecchi, M. R., & McMahon, A. P. (2003) · Genes & Development · doi:10.1101/gad.1044903 · Cited by 299 · see citing works
Lagasse, E., & Weissman, I. L. (1997) · Cell · doi:10.1016/s0092-8674(00)80290-1 · Cited by 287 · see citing works
Miao, D. (2005) · Journal of Clinical Investigation · doi:10.1172/jci24918 · Cited by 277 · see citing works
MAEDA, Y. Y., Nakamura, E., Nguyen, M., Suva, L. J., Swain, F. L., Razzaque, M. S., Mackem, S., & Lanske, B. (2007) · Proceedings of the National Academy of Sciences · doi:10.1073/pnas.0608449104 · Cited by 267 · see citing works
Bone Morphogenetic Proteins in Bone Stimulate Osteoclasts and Osteoblasts During Bone Development
Okamoto, M., Murai, J., Yoshikawa, H., & Tsumaki, N. (2006) · Journal of Bone and Mineral Research · doi:10.1359/jbmr.060411 · Cited by 212 · see citing works
Bringhurst, F. R. (1993) · Endocrinology · doi:10.1210/en.132.5.2090 · Cited by 195 · see citing works
Mak, K. K., Chen, M.-H., Day, T. F., et al. (2006) · Development · doi:10.1242/dev.02546 · Cited by 191 · see citing works
Self-citationNevoid basal cell carcinoma syndrome. Clinical findings in 37 Italian affected individuals
Muzio, L. L., Nocini, P. F., Savoia, A., et al. (1999) · Clinical Genetics · doi:10.1034/j.1399-0004.1999.550106.x · Cited by 178 · see citing works
Bringhurst, F. R., Jüppner, H., Guo, J., et al. (1993) · Endocrinology · doi:10.1210/endo.132.5.8386606 · Cited by 161 · see citing works
Nissenson, R. A., Diep, D., & Strewler, G. J. (1988) · Journal of Biological Chemistry · doi:10.1016/s0021-9258(18)37641-5 · Cited by 155 · see citing works
Fujimori, A., Cheng, S. L., Avioli, L. V., et al. (1992) · Endocrinology · doi:10.1210/endo.130.1.1727705 · Cited by 151 · see citing works
van der Eerden, B. C. J., Karperien, M., Gevers, E. F., et al. (2000) · Journal of Bone and Mineral Research · doi:10.1359/jbmr.2000.15.6.1045 · Cited by 149 · see citing works
Mechanisms of Disease: roles of OPG, RANKL and RANK in the pathophysiology of skeletal metastasis
Blair, J. M., Zhou, H., Seibel, M. J., & Dunstan, C. R. (2006) · Nature Clinical Practice Oncology · doi:10.1038/ncponc0381 · Cited by 140 · see citing works
Paget’s disease of bone and genetic disorders of RANKL/OPG/RANK/NF-κB signaling.
WHYTE, M. P. (2006) · Annals of the New York Academy of Sciences · doi:10.1196/annals.1346.016 · Cited by 95 · see citing works
Kindblom, J. M., Nilsson, O., Hurme, T., et al. (2002) · Journal of Endocrinology · doi:10.1677/joe.0.174r001 · Cited by 87 · see citing works
Ishida, A., Fujita, N., Kitazawa, R., & Tsuruo, T. (2002) · Journal of Biological Chemistry · doi:10.1074/jbc.m111093200 · Cited by 86 · see citing works
Jemtland, R., Divieti, P., Lee, K., et al. (2003) · Bone · doi:10.1016/s8756-3282(03)00092-9 · Cited by 68 · see citing works
Liu, B.-Y., Guo, J., Lanske, B., Pajevic, P. D., Kronenberg, H. M., & Bringhurst, F. R. (1998) · Endocrinology · doi:10.1210/endo.139.4.5895 · Cited by 59 · see citing works
Expression of Indian Hedgehog During Fracture Healing in Adult Rat Femora
Murakami, S., & Noda, M. (2000) · Calcified Tissue International · doi:10.1007/pl00005843 · Cited by 56 · see citing works
Expression of parathyroid hormone-related protein in rat articular cartilage
Tsukazaki, T., Ohtsuru, A., Enomoto, H., et al. (1995) · Calcified Tissue International · doi:10.1007/bf00310258 · Cited by 49 · see citing works
Murakami, S., Nifuji, A., & Noda, M. (1997) · Endocrinology · doi:10.1210/endo.138.5.5140 · Cited by 45 · see citing works
Expression of mRNA of parathyroid hormone-related peptide in fetal bones of the rat
Karmali, R., Schiffmann, S. N., Vanderwinden, J., et al. (1992) · Cell and Tissue Research · doi:10.1007/bf00645063 · Cited by 40 · see citing works
Guillonneau, X., Tassin, J., Berrou, E., Bryckaert, M., Courtois, Y., & Mascarelli, F. (1996) · Journal of Cellular Physiology · doi:10.1002/(sici)1097-4652(199601)166:1 · Cited by 33 · see citing works
Sontag, W. (1980) · Calcified Tissue International · doi:10.1007/bf02408522 · Cited by 18 · see citing works
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- Authors
- Mak, K. K., Bi, Y., Wan, C., Chuang, P.-T., Clemens, T., Young, M., & Yang, Y.
- Affiliations
- National Human Genome Research Institute (US)
- National Institute of Dental and Craniofacial Research (US)
- University of Alabama at Birmingham (US)
- University of California, San Francisco (US)
- Corresponding author
- Yang, Yingzi
- Venue
- Developmental Cell
- Publisher
- Elsevier BV
- Published
- 2008-05
- Volume
- 14
- Issue
- 5
- Pages
- 674-688
- ISSN
- 1534-5807 (ISSN-L)
- OpenAlex
- W2092827845
- Cited by
- 202
- References
- 69
- Citations by year
- 2026: 6 · 2025: 8 · 2024: 8 · 2023: 9 · 2022: 8 · 2021: 11 · 2020: 18 · 2019: 8 · 2018: 13 · 2017: 10 · 2016: 14 · 2015: 14 · 2014: 11 · 2013: 14 · 2012: 10
- FWCI
- 5.49
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Licence
- Locations
- Developmental Cell (publishedVersion)
- PubMed (publishedVersion)
- Funders
- National Institute of Dental and Craniofacial Research (HL66600, HL67822, R01 AR049410)
- National Institutes of Health
- National Human Genome Research Institute
- Topics
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Bone Metabolism and Diseases
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Hedgehog Signaling Pathway Studies
- Health Sciences › Medicine › Orthopedics and Sports Medicine › Bone health and osteoporosis research
- Keywords
- Hedgehog signaling, bone formation, bone resorption, parathyroid hormone-related protein, RANKL, osteoclastogenesis, pKa, CREB, bone homeostasis, osteopenia, aging, bone loss
- MeSH terms
- Animals, Bone Diseases, Metabolic, Bone Resorption, Cell Differentiation, Cell Survival, Gene Expression Regulation, Organ Size, Osteoblasts, Osteoclasts, Osteogenesis, Signal Transduction, Up-Regulation, Cyclic AMP Response Element-Binding Protein, Cyclic AMP-Dependent Protein Kinases, Parathyroid Hormone-Related Protein, Cell Proliferation, Mice, RANK Ligand, Hedgehog Proteins
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