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Transcription factor C/EBPbeta isoform ratio regulates osteoclastogenesis through MafB

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Item Type:Article
Title:Transcription factor C/EBPbeta isoform ratio regulates osteoclastogenesis through MafB
Creators Name:Smink, J.J., Bégay, V., Schoenmaker, T., Sterneck, E., de Vries, T.J. and Leutz, A.
Abstract:Disequilibrium between bone-forming osteoblasts and bone-resorbing osteoclasts is central to many bone diseases. Here, we show that dysregulated expression of translationally controlled isoforms of CCAAT/enhancer-binding protein beta (C/EBPbeta) differentially affect bone mass. Alternative translation initiation that is controlled by the mammalian target of rapamycin (mTOR) pathway generates long transactivating (LAP(*), LAP) and a short repressive (LIP) isoforms from a single C/EBPbeta transcript. Rapamycin, an inhibitor of mTOR signalling increases the ratio of LAP over LIP and inhibits osteoclastogenesis in wild type (WT) but not in C/EBPbeta null (c/ebpbeta(-/-)) or in LIP knock-in (L/L) osteoclast precursors. C/EBPbeta mutant mouse strains exhibit increased bone resorption and attenuated expression of MafB, a negative regulator of osteoclastogenesis. Ectopic expression of LAP and LIP in monocytes differentially affect the MafB promoter activity, MafB gene expression and dramatically affect osteoclastogenesis. These data show that mTOR regulates osteoclast formation by modulating the C/EBPbeta isoform ratio, which in turn affects osteoclastogenesis by regulating MafB expression.
Keywords:Bone Homeostasis, CCAAT/Enhancer Binding Protein beta, MafB, mTOR, Osteoclast, Animals, Mice
Source:EMBO Journal
Publisher:Nature Publishing Group
Page Range:1769-1781
Date:17 June 2009
Official Publication:https://doi.org/10.1038/emboj.2009.127
PubMed:View item in PubMed

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