Epigenetic toxicity of PFOA and GenX in HepG2 cells and their roles in lipid metabolism.
PFOA 和 GenX 在 HepG2 细胞中的表观遗传毒性及其在脂质代谢中的作用。
- 作者列表："Wen Y","Mirji N","Irudayaraj J
:Perfluorooctanoic acid (PFOA), an extremely persistent perfluoroalkyl substance (PFAS), and 2,3,3,3-Tetrafluoro-2-(heptafluoropropoxy) propanoic acid (GenX), its shorter chain alternative, have been implicated in hepatocellular damage with unusual fat deposit and liver enlargement. In this study we explored the underlying mechanisms of PFOA and GenX induced hepatocellular damage. Liver hepatocellular carcinoma cell line HepG2 was used as a model to study induced liver inflammation in vitro at the cellular, genetic, and epigenetic levels. HepG2 cells were exposed to PFOA or GenX for 48 h and the DNA and RNA were extracted and analyzed. mRNA expression of PFOA exposed cells showed that the cell cycle genes were affected significantly, as well as the ten-eleven translocation methylcytosine dioxygenases (TETs) and the essential lipid metabolism genes. However, GenX did not have as significant an effect on the expression levels. Global methylation levels of HepG2 cells was found to be inversely proportion to PFOA exposure levels and had corresponding trends with mRNA expression of most genes of interest. Upon comparison, the global methylation level of GenX decreased and then increased. Our work points to the fact that PFOA induced epigenetic changes may play a major role in lipid metabolism gene regulation contributing to higher levels of epigenetic toxicity than GenX.
: 全氟辛酸 (PFOA)，一种非常持久的全氟烷基物质 (PFAS)，和 2,3，3,3-四氟-2-(七氟丙氧基) 丙酸 (GenX)，其较短的链替代品, 与不寻常的脂肪沉积和肝脏肿大的肝细胞损伤有关。在本研究中，我们探讨了 PFOA 和 GenX 诱导肝细胞损伤的潜在机制。以肝癌细胞系 HepG2 为模型，在细胞、遗传和表观遗传水平上研究体外诱导肝脏炎症。HepG2 细胞暴露于 PFOA 或 GenX 48 h，提取 DNA 和 RNA 并进行分析。PFOA 暴露细胞的 mRNA 表达显示，细胞周期基因以及 10-11 转位甲基胞嘧啶双加氧酶 (TETs) 和必需脂质代谢基因受到显著影响。然而，GenX 对表达水平没有显著影响。发现 HepG2 细胞的整体甲基化水平与 PFOA 暴露水平成反比，并与大多数感兴趣基因的 mRNA 表达具有相应的趋势。经比较，GenX 的全局甲基化水平降低，然后升高。我们的工作指出，PFOA 诱导的表观遗传变化可能在脂质代谢基因调控中发挥主要作用，导致比 GenX 更高水平的表观遗传毒性。
METHODS:BACKGROUND:Given the importance of habitual dietary protein intake, distribution patterns and dietary sources in the aetiology of age-related declines of muscle mass and function, the present study examined these factors as a function of sex and age in Irish adults aged 18-90 years comprising The National Adult Nutrition Survey (NANS). METHODS:In total, 1051 (males, n = 523; females, n = 528) undertook a 4-day semi-weighed food diary. Total, body mass relative intake and percentage contribution to total energy intake of dietary protein were determined in addition to protein distribution scores (PDS), as well as the contribution of food groups, animal- and plant-based foods to total protein intake. RESULTS:Total and relative protein intake [mean (SD)] were highest in those aged 18-35 years [96 (3) g day , 1.32 (0.40) g kg day ], with lower protein intakes with increasing age (i.e. in adults aged ≥65 years [82 (22) g, 1.15 (0.34) g kg day , P < 0.001 for both]. Differences in protein intake between age groups were more pronounced in males compared to females. Protein distribution followed a skewed pattern for all age groups [breakfast, 15 (10) g; lunch, 30 (15) g; dinner, 44 (17) g]. Animal-based foods were the dominant protein source within the diet [63% (11%) versus 37% (11%) plant protein, P < 0.001]. CONCLUSIONS:Protein intake and the number of meals reaching the purported threshold for maximising post-prandial anabolism were highest in young adults, and lower with increasing age. For main meals, breakfast provided the lowest quantity of protein across all age categories and may represent an opportunity for improving protein distribution, whereas, in older adults, increasing the number of meals reaching the anabolic threshold regardless of distribution pattern may be more appropriate.
METHODS:BACKGROUND:Low cardiorespiratory fitness (CRF) increases risk of all-cause mortality and cardiovascular events. Periodic CRF assessment can have an important preventive function. OBJECTIVE:To develop a protocol-free method to estimate CRF in daily life based on heart rate (HR) and body acceleration measurements. METHODS:Acceleration and HR data were collected from 37 subjects (M=49%) while performing a standardized laboratory activity protocol (sitting, walking, running, cycling) and during a 5-days free-living monitoring period. CRF was determined by oxygen uptake (VO2max) during maximal exercise testing. A doubly-labeled water validated equation was used to predict total energy expenditure (TEE) from acceleration data. A fitness index was defined as the ratio between TEE and HR (TEE-pulse). Activity recognition techniques were used to process acceleration features and classify sedentary, ambulatory and other activity types. Regression equations based on TEE-pulse data from each activity type were developed to predict VO2max. RESULTS:TEE-pulse measured within each activity type of the laboratory protocol was highly correlated to VO2max (r from 0.74 to 0.91). Averaging the outcome of each activity-type specific equation based on TEE-pulse from the laboratory data led to accurate estimates of VO2max (RMSE: 300.0 mlO2/min or 10%). The difference between laboratory and free-living determined TEE-pulse was 3.7 ± 11% (r =0.85). The prediction method preserved the prediction accuracy when applied to free-living data (RMSE: 367 mlO2/min or 12%). CONCLUSIONS:Measurements of body acceleration and HR can be used to predict VO2max in daily life. Activity-specific prediction equations are needed to achieve highly accurate estimates of CRF.
METHODS:OBJECTIVE:Postprandial dyslipidemia is a common feature of insulin resistant states and contributes to increased cardiovascular disease risk. Recently, bile acids have been recognized beyond their emulsification properties as important signaling molecules that promote energy expenditure, improve insulin sensitivity, and lower fasting lipemia. While bile acid receptors have become novel pharmaceutical targets, their effects on postprandial lipid metabolism remain unclear. Here we investigated the potential role of bile acids in regulation of postprandial chylomicron production and triglyceride excursion. Approach and Results: Healthy C57BL/6 mice were given an intraduodenal infusion of taurocholic acid (TA) under fat-loaded conditions and circulating lipids were measured. Targeting of bile acid receptors was achieved with GW4064, a synthetic agonist to the farnesoid X receptor (FXR), and with deoxycholic acid (DCA), an activator of the Takeda G-protein-coupled receptor 5. TA, GW4064, and DCA treatments all lowered postprandial lipemia. FXR agonism also reduced intestinal triglyceride content and activity of microsomal triglyceride transfer protein, involved in chylomicron assembly. Importantly, TA effects (but not DCA) were largely lost in FXR knockout mice. These bile acid effects are reminiscent of the anti-diabetic hormone glucagon-like peptide-1 (GLP-1). While the GLP-1 receptor agonist exendin-4 retained its ability to acutely lower postprandial lipemia during bile acid sequestration and FXR deficiency, it did raise hepatic expression of the rate limiting enzyme for bile acid synthesis. CONCLUSIONS:Bile acid signaling may be an important mechanism of controlling dietary lipid absorption and bile acid receptors may constitute novel targets for the treatment of postprandial dyslipidemia.