Induction of adipocyte differentiation by polybrominated diphenyl ethers (PBDEs) in 3T3-L1 cells.

Polybrominated diphenyl ethers (PBDEs) are a class of brominated flame retardants that were extensively used in commercial products. PBDEs are ubiquitous environmental contaminants that are both lipophilic and bioaccumulative. Effects of PBDEs on adipogenesis were studied in the 3T3-L1 preadipocyte cell model in the presence and absence of a known adipogenic agent, dexamethasone (DEX). A PBDE mixture designed to mimic body burden of North Americans was tested, in addition to the technical mixture DE-71 and the individual congener BDE-47. The mixture, DE-71, and BDE-47 all induced adipocyte differentiation as assessed by markers for terminal differentiation [fatty acid binding protein 4 (aP2) and perilipin] and lipid accumulation. Characterization of the differentiation process in response to PBDEs indicated that adipogenesis induced by a minimally effective dose of DEX was enhanced by these PBDEs. Moreover, C/EBPα, PPARγ, and LXRα were induced late in the differentiation process. Taken together, these data indicate that adipocyte differentiation is induced by PBDEs; they act in the absence of glucocorticoid and enhance glucocorticoid-mediated adipogenesis

RT-PCR for terminal differentiation markers expressed in relative units following treatment with 250 nM DEX, 25.5

<p> μ<b>M PBDE mixture, 12</b> μ<b>M DE-71, or 12</b> μ<b>M BDE-47.</b> With regards to aP2 RNA expression levels, for days 1, 2, 4, the number of experimental replicates is 4 for all groups except 250 nM DEX (n = 3). For days 5, 6, 8, the number of experimental replicates is 5 for all treatment groups. With regards to perilipin RNA expression levels, for days 1, 2, 4, the number of experimental replicates is 3 for all treatment groups. For days 5, 6, 8, the number of experimental replicates is 5 for all treatment groups. * indicates a significant difference between control and DEX within the given time point (p<0.05). ^a indicates a significant difference between control and PBDE (p<0.05). ^b indicates a significant difference between control and BDE-47 (p<0.05). ^c indicates a significant difference between control and DE-71 (p<0.05). Data is expressed as mean ± SEM.</p

Exposure protocols for PBDEs.

<p>A) Differentiation protocol for PBDEs. B) Protocol for co-treatment with glucocorticoids (5 nM DEX).</p

Western blotting for terminal differentiation markers.

<p>A) PBDE-induced changes in aP2 and perilipin protein expression, presented with representative blots. Data is expressed as mean ± SEM, n = 3 independent experiments. B) Relative protein expression of aP2 and perilipin following exposure to DE-71, presented with representative blots. Data is expressed as mean ± SEM, n = 4 independent experiments. C) BDE-47-induced changes in aP2 and perilipin expression, presented with representative blots. Data is expressed as mean ± SEM, n = 4 independent experiments. * indicates statistical significance from control, p<0.05.</p

mRNA Expression of PPARγ, C/EBPα, and LXRα during differentiation following treatment with 250 nM DEX, 25.5

<p> μ<b>M PBDE, 12</b> μ<b>M DE-71, or 12</b> μ<b>M BDE-47 in relative units.</b> For <i>PPARγ</i> RNA expression during days 1, 2, 4, the number of experimental repeats is 4 for all treatment groups. For days 5, 6, 8, the number of experimental repeats is 5 for all treatment groups. For <i>C/EBPα</i> and LXRα RNA expression during days 1, 2, 4, the number of experimental repeats is 3 for all treatment groups. For days 5, 6, 8, the number of experimental repeats is 5 for all treatment groups. * statistical difference between control and DEX at the given time point, p<0.05; ^a statistical difference between control and PBDE, p<0.05; ^b statistical difference between control and BDE-47, p<0.05. Data is expressed as mean ± SEM.</p

Nile red staining of lipids.

<p>A) DMSO. B) 250 nM DEX. C) 3.2 μM PBDE mixture. D) 25.5 μM PBDE mixture. E) 3 μM DE-71. F) 12 μM DE-71. G) 1.5 μM BDE-47. H) 12 μM BDE-47. I) Percentage of adipocytes present following differentiation.</p

Bisphenol A and Bisphenol S Induce Distinct Transcriptional Profiles in Differentiating Human Primary Preadipocytes

<div><p>Bisphenol S (BPS) is increasingly used as a replacement plasticizer for bisphenol A (BPA) but its effects on human health have not been thoroughly examined. Recent evidence indicates that both BPA and BPS induce adipogenesis, although the mechanisms leading to this effect are unclear. In an effort to identify common and distinct mechanisms of action in inducing adipogenesis, transcriptional profiles of differentiating human preadipocytes exposed to BPA or BPS were compared. Human subcutaneous primary preadipocytes were differentiated in the presence of either 25 μM BPA or BPS for 2 and 4 days. Poly-A RNA-sequencing was used to identify differentially expressed genes (DEGs). Functional analysis of DEGs was undertaken in Ingenuity Pathway Analysis. BPA-treatment resulted in 472 and 176 DEGs on days 2 and 4, respectively, affecting pathways such as liver X receptor (LXR)/retinoid X receptor (RXR) activation, hepatic fibrosis and cholestasis. BPS-treatment resulted in 195 and 51 DEGs on days 2 and 4, respectively, revealing enrichment of genes associated with adipogenesis and lipid metabolism including the adipogenesis pathway and cholesterol biosynthesis. Interestingly, the transcription repressor N-CoR was identified as a negative upstream regulator in both BPA- and BPS-treated cells. This study presents the first comparison of BPA- and BPS-induced transcriptional profiles in human differentiating preadipocytes. While we previously showed that BPA and BPS both induce adipogenesis, the results from this study show that BPS affects adipose specific transcriptional changes earlier than BPA, and alters the expression of genes specifically related to adipogenesis and lipid metabolism. The findings provide insight into potential BPS and BPA-mediated mechanisms of action in inducing adipogenesis in human primary preadipocytes.</p></div

Hepatic enzyme ALT as a marker of glucose abnormality in men with cystic fibrosis.

AimCystic fibrosis (CF) patients are at high risk of developing CF-related diabetes (CFRD). In non-CF patients, liver disease, specifically steatosis and non-alcoholic fatty liver disease (NAFLD), is strongly associated with type 2 diabetes. We compared glycemic status and metabolic profiles in CF patients according to a biomarker of hepatic injury, alanine aminotransferase (ALT).MethodsWe conducted a cross-sectional study among 273 adult CF patients recruited from the Montreal CF Cohort. A 2-hour oral glucose tolerance test (OGTT) was performed to collect glucose and insulin measures every 30 minutes. Fasting ALT levels and anthropometric measures were also obtained. Patients were categorized into 2 groups based on ALT cut-off of 25 U/L.ResultsPatients in the high ALT group were mostly men (83%), had higher mean weight and BMI (pConclusionsAdult CF men with higher ALT show an increased frequency of dysglycemia and de novo CFRD, lower insulin sensitivity and higher eight. Our data suggests that ALT levels could be an interesting tool to guide targeted diabetes screening, particularly among CF men. Prospective studies are needed to confirm these observations