ArrayExpress Uploaderarrayexpress_sidmouseCol1-Dlk1wild type825807DLK1/FA-1 (delta-like 1/fetal antigen-1) is a transmembrane protein belonging to Notch/Delta family that acts as a membrane-associated or...E-GEOD-22113/profile/8773/arrayexpressuploader12bodybonebone marrowestrogenmembranenotchosteoblastproteinvolumeDec.12, 2014FalseE-GEOD-22113_A-AFFY-23dlk1-is-a-novel-regulator-of-bone-mass-that-mediatDLK1 Is a Novel Regulator of Bone Mass That Mediates Estrogen-Deficiency Induced Bone Loss in MiceNov.23, 2014DLK1/FA-1 (delta-like 1/fetal antigen-1) is a transmembrane protein belonging to 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 over-expressing mice (Col1-Dlk1). Col1-Dlk1 mice displayed growth retardation and significantly reduced total body weight and bone mineral density (BMD). μCT-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 as compared to WT. At a cellular level, DLK1 markedly reduced the total number of bone marrow (BM)-derived CFU-F, as well as their osteogenic capacity. In a number of in vitro culture systems, DLK1 stimulated osteoclastogenesis indirectly through osteoblast-dependent increased production of pro-inflammatory bone resorbing cytokines (e.g, Il7, Tnfa and Ccl3). We found that ovariectomy (ovx)-induced bone loss was associated with increased production of DLK1 in bone marrow by activated T-cells. However, Dlk1-/- mice were protected from ovx-induced bone loss. Thus, we identified DLK1 as a novel regulator of bone mass that function 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. Calvarial osteoblasts were grown from neonatal mice overexpressing Dlk1 and their non-transgenic littermate controls. Three separate cultures from each of the two genotypes were combined and analysed by Affymetrix microarray MOE430 2.0.http://www.ebi.ac.uk/arrayexpress/experiments/E-GEOD-22113http://www.ebi.ac.uk/arrayexpress/experiments/E-GEOD-22113/samples/