SEC14L3激活PI3K/Akt信号通路调控BaP与DEHP致细胞损伤的机制研究

Indoor air pollution is gradually gaining more attention as an important public health issue. The characteristics of health impacts of indoor air pollution are chronic low dose exposures and combined effects of multiple pollutants. Benzo[a]pyrene (B[a]P) and di(2-ethylhexyl)phthalate(DEHP) can induce oxidative stress and inflammatory response, as well as mitochodrial dysfucntion, cell injury and even cell death.PI3K/Akt signaling pathway regulates inflammentory response.The expression of Sec14L3 mRNA/protein is associated with the development of airway inflammation and regualtion of cholesterol biosynthetic process.PIP3 is a specific lagand for the SEC14L3 protein.However,SEC14L3 roles in the molecular mechanisms of oxidative stress and the activation of PI3K/Akt pathway are unclear.In the present study, the cell models of B[a]P and DEHP co-exposure will be created using several cell lines including A549(human lung epithelial cell line), normal human liver cell line), HepG2(Human hepatocellular liver carcinoma cell line). Subsequently, the indicators of oxidative stress, mitochondrial dysfunction and cellular injury were analyzed in the cell culture models. To provide scientific basis for SEC14L3 as a predictor of the inflammatory status, a potential linkage between SEC14L3 and the activation of PI3K/Akt signaling pathway in relation to the mitochondrial dysfunction was further investigated using the cell models.

人类长期、低剂量暴露室内环境多种污染物可危及其健康，研究室内环境重要污染物的毒理机制是环境卫生研究的重要内容之一。苯并芘(B[a]P)和邻苯二甲酸二乙基己酯(DEHP)是现代居室环境中重要的污染物。研究发现PI3K/AKt通路参与这两种污染物诱导的细胞氧化应激和炎症反应，细胞损伤甚至死亡的生物学效应的调控。Sec14L3是近年备受关注的新气道标志物，它参与胆固醇生物合成过程，而磷脂酰肌醇-3,4,5-三磷酸(PIP3)是SEC14L3的特定配体。不过，SEC14L3在这两种环境污染物诱导的氧化应激和活化PI3k/Akt通路中的调控机制仍不十分清楚。本项目拟用人肺细胞和人肝细胞建立B[a]P和DEHP联合染毒细胞模型，初步明确B[a]P和DEHP经氧化应激与炎症反应介导的线粒体功能障碍和细胞损伤的联合毒性作用，重点研究B[a]P和DEHP致细胞联合毒性作用中SEC14L3激活PI3K/Akt通路调控线粒体功能的机制，为SEC14L3作为机体炎症损伤预警指标提供科学依据。

多环芳烃和邻苯二甲酸酯类环境污染物对人体健康的威胁已备受关注，但复合暴露两类环境污染物所致人群健康风险与联合毒性机制仍不清楚。在建立的DEHP与BaP联合染毒A549细胞、Beas-2B细胞和HepG2细胞模型基础上，研究了此联合染毒对细胞线粒体功能及其命运的影响，PTEN/PI3K/AKT/mTOR信号通路以及MAPK-ERK信号通路和p38MAPK/信号通路分别调控细胞增殖抑制和细胞衰老相关分泌表型(senescence-associated secretory phenotype, SASP)的机制，评估了暴露此两类环境污染物的城市社区人群的健康风险。研究表明，一定剂量DEHP与50.00μM BaP联合处理HepG2细胞诱导了氧化应激，可致线粒体钙稳态调节异常以及IL-6和IL-8的mRNA和蛋白表达上调，PTEN-PI3K-Akt信号通路参与调控细胞增殖抑制，但细胞周期和凋亡未受影响。50.00μM BaP可削弱一定剂量DEHP致HepG2细胞SEC14L2基因的mRNA表达下调和相对端粒长度的缩短，增加DEHP致HepG2细胞线粒体DNA拷贝数降低。10.00μM U0126抑制剂通过影响ERK信号通路可削弱500.00μM DEHP与50.00μM BaP致HepG2细胞早期衰老相关蛋白表达的降低及SEC14L3蛋白上调。在该研究人群中，尿多环芳烃羟基代谢物和邻苯二甲酸酯类代谢物水平分别与相对端粒长度降低和线粒DNA拷贝数降低呈相关性，但未见两类环境污染物暴露对机体相对端粒长度和线粒DNA拷贝数的联合效应。此两类尿代谢物与机体DNA氧化损伤程度均呈正相关。尿多环芳烃羟基代谢物和尿邻苯二甲酸酯类代谢物水平与机体FEV1和FVC值分别呈负相关和正相关，但未见暴露两类环境污染物对FEV1和FVC的联合效应。此研究为深入评估人群复合暴露此两类环境污染物的健康风险提供了有益的科学依据。