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Yang M, Trettel LB, Adams DJ, Harrison JR, Canalis E, Kream BE. Col3.6-HSD2 transgenic mice: a glucocorticoid loss-of-function model spanning early and late osteoblast differentiation. Bone 2010; 47:573-82. [PMID: 20541046 PMCID: PMC2926146 DOI: 10.1016/j.bone.2010.06.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2009] [Revised: 05/26/2010] [Accepted: 06/01/2010] [Indexed: 01/08/2023]
Abstract
The goal of this study was to characterize the bone phenotype and molecular alterations in Col3.6-HSD2 mice in which a 3.6-kb Col1a1 promoter fragment drives 11beta-HSD2 expression broadly in the osteoblast lineage to reduce glucocorticoid signaling. Serum corticosterone was unchanged in transgenic females excluding a systemic effect of the transgene. Adult transgenic mice showed reduced vertebral trabecular bone volume and reduced femoral and tibial sub-periosteal and sub-endosteal areas as assessed by microCT. In adult female transgenic mice, histomorphometry showed that vertebral bone mass and trabecular number were reduced but that osteoblast and osteoclast numbers and the mineral apposition and bone formation rates were not changed, suggesting a possible developmental defect in the formation of trabeculae. In a small sample of male mice, osteoblast number and percent osteoid surface were increased but the mineral apposition bone formation rates were not changed, indicating subtle sex-specific phenotypic differences in Col3.6-HSD2 bone. Serum from transgenic mice had decreased levels of the C-terminal telopeptide of alpha1(I) collagen but increased levels of osteocalcin. Transgenic calvarial osteoblast and bone marrow stromal cultures showed decreased alkaline phosphatase and mineral staining, reduced levels of Col1a1, bone sialoprotein and osteocalcin mRNA expression, and decreased cell growth and proliferation. Transgenic bone marrow cultures treated with RANKL and M-CSF showed greater osteoclast formation; however, osteoclast activity as assessed by resorption of a calcium phosphate substrate was decreased in transgenic cultures. Gene profiling of cultured calvarial osteoblasts enriched in the Col3.6-HSD2 transgene showed modest but significant changes in gene expression, particularly in cell cycle and integrin genes. In summary, Col3.6-HSD2 mice showed a low bone mass phenotype, with decreased ex vivo osteogenesis. These data further strengthen the concept that endogenous glucocorticoid signaling is required for optimal bone mass acquisition and highlight the complexities of glucocorticoid signaling in bone cell lineages.
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Affiliation(s)
- Maobin Yang
- Department of Medicine, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT 06030, USA
| | - Lorin B. Trettel
- Department of Medicine, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT 06030, USA
| | - Douglas J. Adams
- Department of Orthopaedic Surgery, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT 06030, USA
| | - John R. Harrison
- Department of Craniofacial Sciences, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT 06030, USA
| | - Ernesto Canalis
- Department of Research, Saint Francis Hospital and Medical Center, 114 Woodland, Street Hartford, Hartford, CT 06105-1299
| | - Barbara E. Kream
- Department of Medicine, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT 06030, USA
- Department of Orthopaedic Surgery, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT 06030, USA
- Department of Genetics and Developmental Biology, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT 06030, USA, and Department of Research, Saint Francis Hospital and Medical Center, 114 Woodland, Street Hartford, Hartford, CT 06105-1299
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