亚砷酸钠胁迫下酵母防御基因的差异表达对细胞凋亡的影响

Arsenic, one of the most toxic metalloid pollutants in the environment, is widely distributed in air, water and soil. Arsenic may enter human body through inhalation, ingestion, or skin absorption, and chronic arsenic exposure might be associated with increased the risk of various diseases, such as neurotoxicity, birth defects and metabolic disorders. Epidemiological studies showed that people exposed to high levels of arsenic are prone to develop skin, liver, and lung cancers. However, the exact mechanisms of arsenic toxicity are not yet well understood. Saccharomyces cerevisiae has been investigated intensively as it has simple, well understood genetics and is amenable to modification by gene technology, so it has been used as a eukaryotic model for common biological processes. In this study, the effect of arsenite-induced oxidative stress on apoptosis in yeast cells was analyzed. The present subject subject aims to study the differential expression of defense-related genes and apoptosis mechanism of yeast cells in response to sodium arsenite, employing genetic chip, Real-time PCR, proteomic and other molecular tools. To further understanding of mechanisms of arsenite toxicity and identify the potential biomarkers for arsenite exposure, the present study was carried out in several levels including cell, protein and gene based on our previous studies.

砷是常见的、对人类健康危害比较严重的环境污染物之一，可通过皮肤、呼吸道和消化道等途径进入人体，导致身体组织器官发生病变，从而引起多种疾病和癌症的发生。因此，砷毒性研究已经成为大家关注的焦点之一。近年来的研究发现，砷化物能抑制细胞分裂，诱导细胞凋亡。然而，砷化物的毒性作用机制不是很清楚。因此，本课题以模式生物酵母为材料，研究亚砷酸钠的毒性机理。本项目拟通过检测亚砷酸钠胁迫下酵母细胞的氧化应激水平和凋亡情况，并结合基因芯片技术、实时定量PCR、蛋白组学、酵母杂交等多种技术，分析防御基因的差异表达对细胞凋亡的影响，从多个层面上探讨亚砷酸钠的毒性作用机理。本项目是在已有基础上更加深入的探索，可拓展人们对砷毒性的认识，寻找砷毒性的生物标记物。

砷是广泛存在于自然界中的环境诱变剂，可诱导细胞发生凋亡。然而，砷化物的毒性作用机制不是很清楚。酵母是一种研究真核生物细胞学机制的模式生物，已被广泛用于细胞分裂和死亡等多种复杂信号途径的研究。因此，本项目以酵母细胞为材料，研究了亚砷酸钠胁迫对酵母细胞氧化应激水平和凋亡的影响，并结合基因组学和蛋白组学等多种技术分析了酵母细胞防御基因在亚砷酸钠胁迫下的表达变化及其对细胞凋亡的影响，从多个层面上探讨亚砷酸钠的毒性作用机理。研究结果显示，亚砷酸钠可抑制酵母细胞生长，改变细胞内抗氧化酶活性，较高浓度时胞内ROS、NO水平和MDA含量显著增高，引起细胞氧化损伤；亚砷酸钠可诱导酵母细胞死亡，经DAPI染色，AnnexinⅤ/PI及TUNNEL检测发现，亚砷酸钠诱导的酵母细胞死亡为凋亡；测序结果发现，亚砷酸钠可在转录组水平和蛋白组水平上改变抗氧化相关基因的表达；利用抗氧化基因相关突变体进一步证实了亚砷酸钠诱导的细胞凋亡与氧化胁迫有关，防御基因的差异表达在细胞凋亡中发挥着重要作用。