Bisphenol A induces cholesterol biosynthesis in HepG2 cells via SREBP-2/HMGCR signaling pathway
Bisphenol A induces cholesterol biosynthesis in HepG2 cells via SREBP-2/HMGCR signaling pathway
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DOI：
10.2131/jts.44.481
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发表时间：
2019-01-01
影响因子：
2
通讯作者：
Feng, Dan
中科院分区：
文献类型：
--
作者：
Li, Qingrong;Zhang, Hongmin;Feng, Dan
双酚A （BPA）是一种人类经常接触的环境化学物质，已被证明会增加胆固醇水平，但其分子机制尚不清楚。鉴于胆固醇的生物合成在提高胆固醇水平中起着重要作用，本研究旨在探讨BPA对HepG2细胞胆固醇生物合成的影响及其可能的机制。不同浓度双酚A处理HepG2细胞24小时，采用商用酶分析试剂盒检测HepG2细胞总胆固醇水平和3-羟基-3-甲基戊二酰辅酶A还原酶（HMGCR）活性，采用qPCR、Western blotting和免疫荧光法分别检测甾醇调节元件结合蛋白-2（SREBP-2）和HMGCR mRNA和蛋白表达水平。用不同浓度的BPA （0.1 nM近似于10 μ M）处理HepG2细胞24小时后，我们发现环境相关浓度的BPA （1 nM和10 nM）显著增加HepG2细胞总胆固醇含量、HMGCR活性和表达，但在100 nM、μ M和10 μ M剂量下，BPA对胆固醇的生物合成没有刺激作用。整个剂量-反应关系遵循非单调的剂量反应，如倒u形。利用人SREBP-2小干扰RNA，我们进一步发现BPA对胆固醇生物合成和HMGCR表达的刺激作用可以通过阻断SREBP-2通路来阻止。本研究为了解BPA暴露的潜在脂肪毒性提供了重要意义，也表明低剂量BPA通过上调SREBP-2/HMGCR信号通路诱导肝脏胆固醇生物合成。
Bisphenol A (BPA), an environmental chemical to which humans are commonly exposed, has been shown to increase cholesterol level but the molecular mechanism is not clear. Since cholesterol biosynthesis plays an important role in elevating cholesterol level, the aim of the present study is to explore the effects of BPA on cholesterol biosynthesis in HepG2 cells and its possible mechanisms. HepG2 cells were treated with different concentrations of BPA for 24 hr, the total cholesterol level and the activity of 3-Hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR) were measured using commercial enzymatic assay kits, and the mRNA and protein expression levels of sterol regulatory element binding protein-2(SREBP-2) and HMGCR were analyzed by qPCR, Western blotting and immunofluorescence, respectively. After treating HepG2 cells with different concentrations (0.1 nM similar to 10 mu M) of BPA for 24 hr, we found that BPA at the environmentally relevant concentrations of 1 nM and 10 nM significantly increased the total cholesterol content, the activity and expression of HMGCR in HepG2 cells, but at 100 nM, mu M and 10 mu M doses, BPA had no stimulatory effect on cholesterol biosynthesis. The whole dose-response relationship follows non-monotonic dose responses, such as an inverted U-shape. Using human SREBP-2 small interfering RNA, we further discovered that the stimulatory effects of BPA on cholesterol biosynthesis and HMGCR expression could be prevented by blockade of the SREBP-2 pathway. This study provides important implications for understanding the potential lipotoxicity of BPA exposure, and it also indicates that low-dose BPA induces hepatic cholesterol biosynthesis through upregulating the SREBP-2/HMGCR signaling pathway.