College of Food Science and Engneering, Jilin University, Changchun, Jilin, 130062, People's Republic of China; Key Laboratory of Zoonosis, Ministry of Education College of Veterinary Medicine, Jilin University, Changchun, Jilin, 130062, People's Republic of China.
College of Food Science and Engneering, Jilin University, Changchun, Jilin, 130062, People's Republic of China.
Food Chem Toxicol. 2020 Oct;144:111575. doi: 10.1016/j.fct.2020.111575. Epub 2020 Jul 21.
3-chloro-1, 2-propanediol (3-MCPD) is a well-known contaminant that was produced in the thermal processing of food. Dietary intake represents the greatest source of exposure to 3-MCPD. Autophagy is an important catabolic pathway that plays an important role in liver physiological function. Evidence suggests that 3-MCPD exposure causes toxicity in liver, but the mechanism remains unknown. Here, we explored the effects of 3-MCPD on autophagic flux and traced the molecular mechanism in HepG2 cells. The data showed 3-MCPD exposure promoted the accumulation of autophagosomes in HepG2 cells. Subsequently, by detected te expression of LC3-Ⅱ and P62 and transfection of mRFP-GFP-LC3 adenovirus, we found that the accumulation of autophagosomes was caused by inhibition of autophagic flux. After that, we investigate lysosomal function and found that 3-MCPD induced lysosomal alkalinization. Further, we detected the expression of TFEB, which is a key nuclear transcription factor in control of lysosome biogenesis and function. We found that 3-MCPD inhibited the nuclear expression of TFEB and mRNA levels of some target genes of TFEB. In order to further verify the role of TFEB in autophagic flux blockage in HepG2 cells induced by 3-MCPD, we overexpressed TFEB by transfection with adenovirus and found that both autophagy inhibition and lysosomal alkalization induced by 3-MCPD were alleviated. These results suggested that 3-MCPD could induce the autophagic flux blockage in HepG2 cells. The possible mechanism was due to the destruction of lysosomal function.
3-氯-1,2-丙二醇（3-MCPD）是一种在食品热加工过程中产生的已知污染物。饮食摄入是接触 3-MCPD 的最大来源。自噬是一种重要的分解代谢途径，在肝脏生理功能中发挥着重要作用。有证据表明，3-MCPD 暴露会导致肝脏毒性，但机制尚不清楚。在这里，我们研究了 3-MCPD 对自噬流的影响，并追踪了 HepG2 细胞中的分子机制。结果表明，3-MCPD 暴露会促进 HepG2 细胞中自噬体的积累。随后，通过检测 LC3-Ⅱ和 P62 的表达以及 mRFP-GFP-LC3 腺病毒的转染，我们发现自噬体的积累是由于自噬流的抑制所致。之后，我们研究了溶酶体功能，发现 3-MCPD 诱导溶酶体碱化。进一步检测 TFEB 的表达，TFEB 是控制溶酶体发生和功能的关键核转录因子。我们发现 3-MCPD 抑制了 TFEB 的核表达以及 TFEB 的一些靶基因的 mRNA 水平。为了进一步验证 TFEB 在 3-MCPD 诱导的 HepG2 细胞自噬流阻断中的作用，我们通过腺病毒转染过表达 TFEB，发现 3-MCPD 诱导的自噬抑制和溶酶体碱化均得到缓解。这些结果表明，3-MCPD 可诱导 HepG2 细胞自噬流阻断。其可能的机制是由于溶酶体功能的破坏。
