title: The protective role of bone morphogenetic protein-8 in the glucocorticoid-induced apoptosis on bone cells.
abstract: One of the side effects associated with glucocorticoid therapy is glucocorticoid-induced bone loss. Glucocorticoids partly detain bone formation via the inhibition of osteoblastic function, however, the exact mechanism of this inhibition remains elusive. In this study, we examined the effect of dexamethasone, an active glucocorticoid analogue, on cell viability and expression of bone remodelling-related genes in primary mouse calvarial and cloned MC3T3-E1 osteoblasts. Using sensitive biochemical assays, we demonstrated the apoptotic effect of dexamethasone on osteoblastic cells. Then, utilizing Taqman probe-based quantitative RT-PCR technology, gene expression profiles of 111 bone metabolism-related genes were determined. As a result of dexamethasone treatment we have detected significant apoptotic cell death, and six genes, including Smad3, type-2 collagen α-1, type-9 collagen α-1, matrix metalloproteinase-2, bone morphogenetic protein-4 and bone morphogenetic protein-8 showed (BMP-8) significant changes in their expression on a time- and concentration-dependent manner. BMP-8, (a novel player in bone-metabolism) exhibited a two orders of magnitude elevation in its mRNA level and highly elevated protein concentration by Western blot in response to dexamethasone treatment. The knockdown of BMP-8 by RNA interference significantly increased dexamethasone-induced cell death, confirming a protective role for BMP-8 in the glucocorticoid-induced apoptosis of osteoblasts. Our results suggest that BMP-8 might be an essential player in bone metabolism, especially in response to glucocorticoids.
authors.affiliation: 1st Department of Internal Medicine of Semmelweis University, Budapest, Hungary. jkosa@bel1.sote.hu
authors.forename: János P
authors.initials: JP
authors.lastname: Kósa
authors.forename: Adrián
authors.initials: A
authors.lastname: Kis
authors.forename: Krisztián
authors.initials: K
authors.lastname: Bácsi
authors.forename: Bernadett
authors.initials: B
authors.lastname: Balla
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Nagy
authors.forename: István
authors.initials: I
authors.lastname: Takács
authors.forename: Gábor
authors.initials: G
authors.lastname: Speer
authors.forename: Péter
authors.initials: P
authors.lastname: Lakatos
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001681:Biological Assay; D015153:Blotting, Western; D019485:Bone Morphogenetic Proteins / Q000235:genetics / Q000378:metabolism*; D053148:Caspase 3 / Q000378:metabolism; D053179:Caspase 7 / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D019610:Cytoprotection / Q000187:drug effects*; D003907:Dexamethasone / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000187:drug effects; D055785:Gene Knockdown Techniques; D005938:Glucocorticoids / Q000494:pharmacology*; D051379:Mice; D010006:Osteoblasts / Q000166:cytology* / Q000187:drug effects* / Q000201:enzymology; D034741:RNA, Small Interfering / Q000378:metabolism; D012886:Skull / Q000166:cytology; D013997:Time Factors
chemical_list: D019485:Bone Morphogenetic Proteins; D005938:Glucocorticoids; D034741:RNA, Small Interfering; D003907:Dexamethasone; D000255:Adenosine Triphosphate; D053148:Caspase 3; D053179:Caspase 7