Unknown,Transcriptomics,Genomics,Proteomics

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Glucocorticoid Signaling Defines a Novel Commitment State during Adipogenesis In Vitro

ABSTRACT: Differentiation of 3T3-L1 preadipocytes can be induced by a 2-d treatment with a factor "cocktail" (DIM) containing the synthetic glucocorticoid dexamethasone (dex), insulin, the phosphodiesterase inhibitor methylisobutylxanthine (IBMX) and fetal bovine serum (FBS). We temporally uncoupled the activities of the four DIM components and found that treatment with dex for 48 h followed by IBMX treatment for 48 h was sufficient for adipogenesis, whereas treatment with IBMX followed by dex failed to induce significant differentiation. Similar results were obtained with C3H10T1/2 and primary mesenchymal stem cells. The 3T3-L1 adipocytes differentiated by sequential treatment with dex and IBMX displayed insulin sensitivity equivalent to DIM adipocytes, but had lower sensitivity to isoproterenol-stimulated lipolysis and reduced triglyceride content. The nondifferentiating IBMX–then-dex treatment produced transient expression of adipogenic transcriptional regulatory factors C/EBP{beta} and C/EBP{delta}, and little induction of terminal differentiation factors C/EBP{alpha} and PPAR{gamma}. Moreover, the adipogenesis inhibitor preadipocyte factor-1 (Pref-1) was repressed by DIM or by dex-then-IBMX, but not by IBMX-then-dex treatment. We conclude that glucocorticoids drive preadipocytes to a novel intermediate cellular state, the dex-primed preadipocyte, during adipogenesis in cell culture, and that Pref-1 repression may be a cell fate determinant in preadipocytes. We sought to define the genes differentially expressed in response to dexamethasone (dex) in 3T3L1 mouse preadipocytes. We treated 3T3L1 cells with dex or DMSO vehicle for 2 or 36 hrs and then prepared total RNA. We hybridized each sample (Cy5) to a pool of the samples, which served as the reference (Cy3) channel. All linear models for differential gene expression were constructed with the "limma" package (Smyth, 2004) in BioConductor (Gentleman et al., 2004). A linear model for dex was constructed to compare the 4 biological replicates of DMSO vehicle treatment with dex treatment at either 2 or 36hr. Genes were considered differentially expressed if at least one probe had log-odds greater than 50:50 in the linear model.

ORGANISM(S): Mus musculus

SUBMITTER: Jason Huff

PROVIDER: E-GEOD-11249 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Glucocorticoid signaling defines a novel commitment state during adipogenesis in vitro.

Pantoja Carlos C Huff Jason T JT Yamamoto Keith R KR

Molecular biology of the cell 20080723 10

Differentiation of 3T3-L1 preadipocytes can be induced by a 2-d treatment with a factor "cocktail" (DIM) containing the synthetic glucocorticoid dexamethasone (dex), insulin, the phosphodiesterase inhibitor methylisobutylxanthine (IBMX) and fetal bovine serum (FBS). We temporally uncoupled the activities of the four DIM components and found that treatment with dex for 48 h followed by IBMX treatment for 48 h was sufficient for adipogenesis, whereas treatment with IBMX followed by dex failed to i ...[more]

PMID: 18653467

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Project description:Background: Exposure to the endocrine-disrupting chemical bisphenol A (BPA) is correlated with obesity and promotes adipogenesis of human preadipocytes into mature adipocytes. However, the mechanism of action of BPA-induced human adipogenesis in vitro remains to be fully characterized. Methods: In this study, potential mechanisms of BPA-induced adipogenesis in primary human preadipocytes were evaluated using gene expression microarray analysis. Preadipocytes from donors with normal body mass indexes were differentiated in the presence of 50 M-BM-5M BPA or 1 M-BM-5M dexamethasone (DEX) for 48 hours. Results: Microarray analysis revealed 235 up-regulated and 138 down-regulated genes following BPA treatment, including sterol regulatory element binding factor 1 (SREBF1), a key transcription factor known to regulate many components of lipid metabolism and adipogenesis. For DEX treated preadipocytes, 1136 genes were up-regulated, including the adipogenic marker lipoprotein lipase, while 1031 genes were down-regulated. Ingenuity Pathway Analysis was used to identify functional annotations of the gene expression changes associated with response to BPA and DEX treatments. BPA exposure was associated with expression changes in the genes involved in the accumulation of triacylglycerol while DEX was linked to metabolism of triacylglycerol and cleavage of fatty acids. The analysis also revealed enrichment of genes in pathways known to be associated with BPA exposure including thyroid-receptor/retinoic X receptor (TR/RXR) activation, mammalian target of rapamycin (mTOR) signaling and cholesterol biosynthesis, whereas DEX treatment was linked to cholesterol biosynthesis and ethanol degradation. Interestingly, alterations in the mTOR pathway in response to BPA did not occur in DEX-treated preadipocytes. Conclusions: Our data suggest that potential mechanisms of action of BPA-induced adipogenesis involve SREBF1, the TR/RXR and the mTOR pathways. The study used 40 samples in total which included 5 replicates (cells from 5 unique donors) of 8 different treatments. The 8 treatments were as follows: 1) untreated (negative) control for 48 hours, 2) 25 uM BPA treated for 48 hours, 3) 50 uM BPA treated for 48 hours, 4) untreated (negative) control + insulin for 48 hours, 5) 25 uM BPA + insulin treated for 48 hours, 6) 50 uM BPA + insulin treated for 48 hours, 7) 1uM Dexamethasone + insulin treated for 48 hours, 8) 1uM Dexamethasone + insulin treated for 96 hours.

Dataset Information

Glucocorticoid Signaling Defines a Novel Commitment State during Adipogenesis In Vitro

Publications

Glucocorticoid signaling defines a novel commitment state during adipogenesis in vitro.

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