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Simulated Microgravity Inhibits Differentiation and Alters Gene Expression Profiles of 2T3 Pre-osteoblasts

ABSTRACT: Exposure to microgravity causes bone loss in humans, and the underlying mechanism is believed to be at least partially due to a decrease in bone formation by osteoblasts. Here, we examined the hypothesis that microgravity changes osteoblast gene expression profiles, resulting in bone loss. For this study, we developed an in vitro system that simulates microgravity using the Random Positioning Machine (RPM) to study the effects of microgravity on 2T3 pre-osteoblast cells grown in gas-permeable culture disks. Exposure of 2T3 cells to simulated microgravity using RPM for up to 9 days significantly inhibited alkaline phosphatase activity, recapitulating an expected bone loss response, without altering cell proliferation and shape. Next, we carried out a DNA microarray analysis to determine the gene expression profile of 2T3 cells exposed to 3 days of simulated microgravity. Among 10,000 genes examined with the microarray, 88 were downregulated while 52 were upregulated significantly by simulated microgravity by more than two-fold in comparison to the static 1g condition. By using real-time PCR assays, we verified the microarray data using some of the expected genes. For example, we confirmed that microgravity induced downregulation of alkaline phosphatase, runt related transcription factor 2 (runx2), osteomodulin, and parathyroid hormone 1 receptor, while confirming upregulation of cathepsin K mRNAs. In addition to the changes of the expected genes, the microarray data identified many more genes. The identification of these gravisensitive genes provide an useful insight in generating further hypotheses regarding their roles not only in microgravity-induced bone loss, but also in general population of patients with similar pathologic conditions such as osteoporosis. Keywords: other

ORGANISM(S): Mus musculus

PROVIDER: GSE1367 | GEO | 2004/05/07

SECONDARY ACCESSION(S): PRJNA90125

REPOSITORIES: GEO

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Simulated Microgravity Inhibits Differentiation and Alters Gene Expression Profiles of 2T3 Pre-osteoblasts

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