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The effect of bisphenol A on human preadipocyte differentiation.

ABSTRACT: 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 µM BPA or 1 µM 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.

ORGANISM(S): Homo sapiens

PROVIDER: GSE56085 | GEO | 2014/04/15

SECONDARY ACCESSION(S): PRJNA242385

REPOSITORIES: GEO

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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.

Project description: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.

Project description:Full title: Expression data from human primary subcutaneous preadipocytes treated with glucocorticoids prior to the initiation of differentiation. Preadipocytes are continuously exposed to glucocorticoids in situ due to both steroid present in the circulatory system as well as adipose tissue specific 11Î²HSD1 activity. While the effects of glucocorticoids during differentiation are well studied, the effect of exposure of preadipocytes to glucocorticoids prior to differentiation is unknown. We therefore treated confluent human primary preadipocytes drived from subcutaneous adipose tissue with the synthetic glucocorticoid dexamethasone for 48 hours prior to the initiation of differentiation and assessed what effect this had on their subsequent potential to differentiate. We found that pretreatment with glucocorticoids had a priming effect and resulted in increased differentiation of these preadipocytes. Furthermore, this treatment was additive to the effects of glucocorticoids during the initial phase of adipogenesis. Microarray analysis performed subsequent to the pretreatment with glucocorticoids (at the time point at which preadipocytes would have been induced to differentiate) identified glucocorticoid-responsive, candidate genes whose altered expression could mediate these effects. keywords: glucocorticoids, glucocorticoid receptor, preadipocytes, adipogenesis, human primary preadipocytes, subcutaneous, adipose tissue Experiment Overall Design: Human subcutaneous primary preadipocytes were purchased from Zen-Bio Inc. Preadipocytes from 5 female donors (average BMI 22.5Â±0.2kg/m2) were pooled prior to the initial seeding in T75 flasks. Cells were maintained at 5% CO2 in DMEM with 1.0g/L glucose, 20% calf serum, 100U/ml penicillin, 100mg/ml streptomycin and 50U/ml nystatin. Cells were expanded once prior to seeding in Nunc-brand 12-well dishes. Upon reaching confluence (24 h post-splitting), preadipocytes were stimulated with vehicle or 1uM dex for 48 hours in growth media containing 3% calf serum. Microarray analysis was performed on duplicate samples.

Project description:Thyroid hormones (THs) play a critical role in development and throughout adulthood. THs act through the thyroid receptor (TR), which binds to the TH response element (TRE) to regulate the expression of target genes. Although TH action has been studied for decades, surprisingly few TREs have been well validated and characterized. In this study we used chromatin immunoprecipitation followed by microarray analysis (ChIP-chip) to identify TR-binding sites in juvenile (postnatal day 15) mice liver. Microarray analysis revealed twelve TR-binding sites consistent between all analyzed samples. In silico analysis was carried out to search for moderately conserved classic TRE sequences within these novel binding regions, which led to the identification of six candidate TREs within three binding regions. Luciferase reporter assays confirmed the presence of a TRE in the promoter region of DEAD (Asp-Glu-Ala-Asp) box polypeptide 54 (Ddx54) and thyroid hormone responsive SPOT14 (Thrsp). The TR/retinoid X receptor (RXR) heterodimer and RXR homodiner were shown to bind the promoter region of Ddx54 and drive gene expression in the presence of 9-cis-retinoic acid (9cRA). The promoter region of Thrsp was shown to allow binding of the TR/RXR heterodimer, and both T3 and 9cRA were able to significantly increase luciferase activity. The RXR homodimer was also able to bind the response element in the promoter region of Thrsp and increase luciferase activity. Overall, ChIP-chip analysis revealed a relatively limited number of TR-binding sites in juvenile mouse liver despite previous studies showing that numerous genes can be affected by TH disruption at that developmental stage, suggesting that TH action may also be mediated through other intermediates. Collectively the results provide an important step towards characterizing TR-binding sites and identifying the underlying drivers of TR-gene regulation. Three samples were analyzed (total input and immunoprecipitated for each samples).

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The effect of bisphenol A on human preadipocyte differentiation.

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