title: Osteoprotegerin mRNA is expressed in primary human osteoblast-like cells: down-regulation by glucocorticoids.
abstract: Osteoprotegerin (OPG) is a recently cloned member of the tumour necrosis factor receptor family. It has been suggested that this secreted glycoprotein acts as an inhibitor of osteoclastic differentiation. Expression of OPG has previously been demonstrated in a number of tissues. However, it is still unclear whether or not OPG is expressed by human osteoblasts. We have used the RNase protection assay to demonstrate the OPG transcript in primary cultured human osteoblast-like cells, human marrow stroma cells and osteosarcoma cell lines. Furthermore, we have studied the effect of glucocorticoids on OPG mRNA levels in these cells. We demonstrate that glucocorticoids decrease the OPG transcript in a dose- and time-dependent manner. The time-course study reveals that hydrocortisone (10(-6) M) decreases OPG mRNA levels within 2 h. This decrease is transient, reaching control levels again after 24 h. Our findings demonstrate that human osteoblasts express the mRNA corresponding to OPG, an inhibitor of osteoclast differentiation. The finding that OPG mRNA levels are decreased by glucocorticoids indicates that a reduced production of OPG from osteoblasts and/or marrow stroma cells could, in part, explain glucocorticoid-induced bone resorption.
authors.affiliation: Research Centre for Endocrinology and Metabolism, Department of Internal Medicine, Sahlgrenska University Hospital, Gothenburg, Sweden.
authors.forename: N O
authors.initials: NO
authors.lastname: Vidal
authors.forename: H
authors.initials: H
authors.lastname: Brändström
authors.forename: K B
authors.initials: KB
authors.lastname: Jonsson
authors.forename: C
authors.initials: C
authors.lastname: Ohlsson
mesh_terms: D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D002478:Cells, Cultured; D003720:Densitometry; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects*; D005821:Genetic Techniques; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D006854:Hydrocortisone / Q000494:pharmacology*; D010006:Osteoblasts / Q000378:metabolism*; D053244:Osteoprotegerin; D018160:Receptors, Cytoplasmic and Nuclear; D018124:Receptors, Tumor Necrosis Factor; D013268:Stimulation, Chemical; D013739:Testosterone / Q000494:pharmacology; D013997:Time Factors; D014407:Tumor Cells, Cultured
chemical_list: D000893:Anti-Inflammatory Agents; D006023:Glycoproteins; D053244:Osteoprotegerin; D018160:Receptors, Cytoplasmic and Nuclear; D018124:Receptors, Tumor Necrosis Factor; C506030:TNFRSF11B protein, human; D013739:Testosterone; D004958:Estradiol; D006854:Hydrocortisone