Bone Abstracts

Delta-like 1/fetal antigen-1 (DLK1/FA1) is a negative regulator of bone mass in vivo as it inhibits osteoblast (OB) and stimulates osteoclast differentiation. However, the molecular mechanisms underlying these effects are not known. Thus, we studied the effect of DLK1/FA1 on different signaling pathways known to regulate OB differentiation. We identified DLK1/FA1 as an inhibitor of BMP2-induced OB differentiation. Stable overexpression of DLK1/FA1 in C2C12 cells or th...

Background: Infantile hypercalcemia occurs in ~15% of patients with Williams Syndrome (WS) and is typically mild. Severe hypercalcemia has been reported in infants/toddlers with WS, requiring treatment with intravenous (IV) saline hydration, furosemide, calcitonin, calcium and vitamin D restriction, and in some cases IV bisphosphonates.Presenting problem: Three cases of infants with WS age 9–13 months presented with severe hypercalcemia, failure to ...

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Here we identify the lipolytic enzyme hepatic lipase (HL, encoded by Lipc) as a novel cell-autonomous regulator of osteoblast function. In an unbiased genome-wide expression analysis, we find Lipc – which was formerly thought to be expressed almost exclusively by the liver – to be highly induced upon osteoblast differentiation, as verified by quantitative Taqman analyses of primary osteoblasts in vitro and of bone samples in vivo. ...

Background: Paget’s disease of Bone (PDB) has a strong genetic component and a candidate locus for the disease has been identified on chromosome 14q32, tagged by rs10498635 located within RIN3 (Albagha et al, Nat Genet 2011). RIN3 encodes a protein that acts as a guanine nucleotide exchange factor for Rab5b and Rab31. Here we investigated the candidacy of RIN3 as a predisposing gene for PDB.Methods: We studied expression of RIN3 by quantita...

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Osteoporosis is common in rheumatoid arthritis (RA). Since osteoblasts express receptors for CXCL8 and CCL20, which are produced by inflammatory cells around the inflamed joints in RA, we hypothesized that CXCL8 and CCL20 contribute to osteoporosis in RA by affecting osteoblast proliferation, differentiation, and osteoblast-osteoclast communication.Primary human osteoblasts were cultured±CXCL8 (2–200 pg/ml) and CCL20 (5–500 pg/ml) for 14 d...

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Delayed fracture healing is frequently experienced in patients with systemic inflammation such as during rheumatoid arthritis (RA). The reasons for this are diverse, but could also be caused by inflammatory cytokines and/or growth factors in serum from patients with active disease. We hypothesized that serum from patients with active RA contains circulating inflammatory factors that inhibit differentiation of osteochondrogenic precursors.Serum was obtain...

Clinical trials involving drug therapies for postmenopausal osteoporosis typically compare effects of the active drug combined with vitamin D (vit D) and calcium (Ca) vs vit D and Ca supplementation on its own. Bone strength is estimated based on the amount of bone, frequently expressed as bone mineral density determined by dual X-ray absorptiometry, and quality of bone, hardly measured in clinical practice.The purpose of the present study was to compare...