Coordinate Expression of Novel Genes During Osteoblast Differentiation

Abstract

To achieve new insights into the coordinate regulation of gene expression during osteoblast differentiation we utilized an approach involving global analysis of gene expression to obtain the identities of messenger RNAs (mRNAs) expressed using an established in vitro model of bone development. MC3T3-E1 osteoblast-like cells were induced to differentiate by the addition of ␤-glycerophosphate (␤-GP) and ascorbic acid. RNA samples derived from induced and uninduced control MC3T3-E1 cells were used to prepare complementary DNA (cDNA) for serial analysis of gene expression (SAGE). A preliminary SAGE database was produced and used to prepare a hybridization array to further facilitate the characterization of changes in the expression levels of 92 of the SAGE-mRNA assignments after induction of osteoblast differentiation, specifically after 6 days and 14 days of ascorbate treatment. SAGE-array hybridization analysis revealed coordinate induction of a number of mRNAs including Rab24, calponin, and calcyclin. Levels of MSY-1, SH3P2, fibronectin, ␣-collagen, procollagen, and LAMP1 mRNAs, present at day 6 postinduction, were markedly reduced by day 14 postinduction. A number of unanticipated and potentially important developmental genes were identified including the transforming growth factor ␤ (TGF-␤) superfamily member Lefty-1. Lefty-1 transcript and translation product were found to be induced during the course of MC3T3-E1 cell differentiation. We present evidence, using

Calcyclin, a Ca2+ Ion-binding Protein, Contributes to the Anabolic Effects of Simvastatin on Bone

“…Furthermore, the expression of S100 in osteoblastic cells was verified in various types of osteosarcomas, in which immunohistochemical staining for S100 was used to analyze the proliferating cells in osteosarcomas, and the main proliferating cells to be stained were found to be mature osteoblast-like cells (27,28). The existence of the S100 family in osteoblasts were confirmed in subsequent studies (18,29). S100 family members share a common S100 calcium-binding motif and have several regulatory functions in, not only protein phosphorylation, some enzyme activities, the dynamics of cytoskeletal components, transcription factors, and Ca 2ϩ homeostasis but also the cell proliferation and differentiation (15,16).…”

“…An interesting feature of the S100 proteins is that they are expressed by epithelial cells and fibroblasts in a cell-specific way (17). Calcyclin is also expressed by osteoblasts (MC3T3-E1 cells) and up-regulated markedly during osteoblast differentiation; however, its roles in bone physiology are unknown (18).…”

Osteoblast-specific expression of MEF induces osteopenia through downregulation of osteoblastogenesis and upregulation of osteoclastogenesis

“…This result is interesting because MEF is proven to be decreased during osteogenic differentiation, (11) whereas Ets2 is expressed at high levels during the differentiation and matrix maturation phase in the MC3T3-E1 model of osteoblast development. (18) If Ets2 is an important player in the osteoblast differentiation and matrix maturation phase, transgenic mice overexpressing Ets2 are expected to have increased bone mass. However, our MEF TG mouse showed osteopenia, and our previous data also showed that MEF has an inhibitory role in osteoblast differentiation.…”

17-β-estradiol up-regulates apolipoprotein genes expression during osteoblast differentiation <i>in vitro </i>

“…This process of differentiation has been subdivided into three developmental stages: proliferation, extracellular matrix synthesis and maturation, and mineralization, each of which as characteristic changes in gene expression (8). Many independent studies of patterns of gene expression during osteoblast differentiation have been reported (9)(10)(11), and those studies found that some apolipoproteins were induced during this process (9).…”