Journal
JOURNAL OF BONE AND MINERAL RESEARCH
Volume 26, Issue 7, Pages 1457-1471Publisher
WILEY
DOI: 10.1002/jbmr.346
Keywords
DLK1; FA1; PREF-1; BONE REMODELING; OSTEOCLAST; OVX; T CELLS
Categories
Funding
- Lundbeck Foundation
- Danish Medical Research Council
- Novo Nordisk Foundation
- Region of Southern Denmark
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Delta-like 1/fetal antigen 1 (DLK1/FA-1) is a transmembrane protein belonging to the Notch/Delta family that acts as a membrane-associated or a soluble protein to regulate regeneration of a number of adult tissues. Here we examined the role of DLK1/FA-1 in bone biology using osteoblast-specific Dlk1-overexpressing mice (Col1-Dlk1). Col1-Dlk1 mice displayed growth retardation and significantly reduced total body weight and bone mineral density (BMD). Micro-computed tomographis (mu CT) scanning revealed a reduced trabecular and cortical bone volume fraction. Tissue-level histomorphometric analysis demonstrated decreased bone-formation rate and enhanced bone resorption in Col1-Dlk1 mice compared with wild-type mice. At a cellular level, Dlk1 markedly reduced the total number of bone marrow (BM)-derived colony-forming units fibroblasts (CFU-Fs), as well as their osteogenic capacity. In a number of in vitro culture systems, Dlk1 stimulated osteoclastogenesis indirectly through osteoblast-dependent increased production of proinflammatory bone-resorbing cytokines (eg, 87, Tnfa, and Ccl3). We found that ovariectomy (ovx)-induced bone loss was associated with increased production of Dlk1 in the bone marrow by activated T cells. Interestingly, Dlk1(-/-) mice were significantly protected from ovx-induced bone loss compared with wild-type mice. Thus we identified Dlk1 as a novel regulator of bone mass that functions to inhibit bone formation and to stimulate bone resorption. Increasing DLK1 production by T cells under estrogen deficiency suggests its possible use as a therapeutic target for preventing postmenopausal bone loss. (C) 2011 American Society for Bone and Mineral Research.
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