苯并[a]芘通过抑制“疑似应激蛋白”MVP致大鼠海马神经元毒性损伤的机制研究

Benzo[a]pyrene (B[a]P) is a typical polycyclic aromatic hydrocarbon and ubiquitous chemical pollutant in the environment with the rapid development of industrialization and urbanization. A vast number of studies conducted over the past few decades have documented the links between B[a]P and various types of cancer. Currently, although the neurotoxicity of B[a]P is gradually being concerned, the exact mechanism of B[a]P -induced neurotoxicity is not clear. Several studies of our research team have shown that B[a]P can impair spatial learning and memory in male SD rat, and hippocampal neurons, down-regulating MVP expression in hippocampus, and changing some genes expression related to signal pathways. In addition, several evidence support that “stress protein” MVP is a cytoprotective protein. Based on our previous research, using the dual-luciferase reporter assay system and ChIP assay in B[a]P-exposed in vivo and in vitro model, the mechanism of B[a]P inhibiting Mvp gene transcription will be clarified. The mechanism of changed hippocampal neuron behavior (including cell proliferation, cell cycle, senescence and apoptosis) will be studied by molecular biology techniques, related to MVP regulating downstream target genes or signal pathways proteins when exposed to B[a]P. In this research, the main hypothesis about B[a]P-downregulated MVP inducing neurotoxicity in Rat hippocampal neuron will be tested, and the possible mechanism of B[a]P-induced neurotoxicity and new theory for preventing B[a]P-induced neurotoxicity will be demonstrated.

苯并[a]芘（B[a]P）是环境中一类最为常见的化学污染物。已有大量B[a]P致癌的研究，但是其神经毒性作用机制仍不明确。本课题组研究发现B[a]P损伤大鼠的空间学习和记忆能力，及海马神经细胞，抑制海马组织中穹窿体主蛋白（MVP）表达，改变多个信号通路分子的mRNA水平，而现有研究表明MVP蛋白作为“疑似应激蛋白”具有细胞保护作用。本研究在前期研究基础上，从B[a]P暴露的动物和细胞模型入手，利用报告基因和ChIP实验明确B[a]P抑制Mvp基因转录的分子机制，并通过现代分子生物学技术探索B[a]P暴露时MVP蛋白调控下游靶基因或相关信号通路分子从而改变海马神经细胞生物学行为（包括细胞增殖、周期、衰老和凋亡）的分子机制。本研究旨在通过验证科学假说：B[a]P通过抑制MVP蛋白影响海马神经元的细胞功能，探讨B[a]P神经毒性作用的可能机制，为防护B[a]P的神经毒性提供新的靶点和理论基础。

苯并[a]芘（B[a]P）是一种常见的环境污染物, 对哺乳动物具有神经毒性，损伤大脑功能并导致认知障碍。B[a]P神经毒性作用机制复杂。本研究采用B[a]P暴露的动物和细胞模型，利用双荧光素酶报告基因检测系统、巢式PCR、RRBS甲基化测序、非编码RNA测序和代谢组学等方法分析了B[a]P抑制Mvp转录的可能机制。并通过现代分子生物学技术探索B[a]P暴露时MVP蛋白调控海马神经细胞生物学行为（包括细胞增殖、周期、衰老和凋亡）的改变，探讨B[a]P神经毒性作用的可能机制。研究发现B[a]P并未损伤Mvp基因的启动子DNA序列，也不直接调控Mvp基因启动子活性，可能是通过rno-miR-215从表观遗传角度抑制Mvp基因转录。过表达MVP蛋白不促进神经细胞增殖，对B[a]P染毒的海马神经细胞没有保护功效。B[a]P引起神经细胞凋亡可能是通过调节SNAP-25导致突触多巴胺释放这一机制。B[a]P导致海马区神经细胞轴突损伤出现脱髓鞘化，这也许与B[a]P驱动小胶质细胞M2向M1极性活化有关。本研究从一定程度上揭示B[a]P的神经毒性可能机制，为防护B[a]P的神经毒性提供了新的理论。