质谱探针技术研究重金属诱导的细胞表观遗传修饰动态变化及其机制

Nowadays the pollution of heavy metals has become a serious global environmental problem. Heavy metals, including cadmium, lead, arsenic, nickel, mercury, etc., can enter and accumulate in biological organisms, which will compromise the normal physiological functions of cells. Many heavy metals are classified as human carcinogens according to the International Agency for Research on Cancer, but the carcinogenesis of heavy metals is still not well understood. In this project, we will focus on the study of the effects of heavy metals on epigenetic modifications by establishing mass spectrometry probe-based method. Through investigating the heavy metals-induced dynamic changes of DNA and RNA modifications as well as the endogenous metabolites, we plan to establish the connections of heavy metals - endogenous metabolites - epigenetic modifications of DNA and RNA. We propose that heavy metals will cause the alteration of activities and expression of enzymes that involve in the epigenetic modifications of DNA and RNA by deteriorating the endogenous metabolites that function as the necessary coenzyme factors. Eventually, the heavy metals-induced changes of enzymes will result in abnormal epigenetic modifications of DNA and RNA, which therefore induce the pathological changes of cells and organisms. In addition, we will further explore the intergenerational changes of DNA and RNA modifications of rats caused by heavy metals. This study will provide in-depth understanding of the molecular mechanisms of carcinogenicity and cytotoxicity induced by heavy metals.

重金属污染已成为当前严重的世界性环境问题。包括镉、铅、砷、镍、汞等在内的重金属进入生物体后，逐渐累积并从多个层面对生物体产生影响，破坏正常的细胞活动，对生物体产生毒害。多种重金属已经被国际癌症研究机构定为人类致癌物质。尽管目前对重金属的细胞毒性和致癌性有一定的研究，但是重金属导致的细胞癌变分子机制还尚不明确。本项目拟通过建立质谱探针-质谱分析的方法，系统研究重金属诱导的DNA和RNA表观遗传修饰含量和位点分布的动态变化，以及分析和表观遗传修饰密切相关的内源性代谢物的变化，探索重金属对动物表观遗传修饰的跨代影响，建立重金属--内源性代谢物--表观遗传修饰之间的关联。通过以上研究，阐明重金属通过损伤细胞内源性代谢物，影响表观遗传修饰酶的表达和活性，从而引起DNA和RNA表观遗传修饰的异常，最终导致细胞毒性的分子机制。

重金属污染已成为当前严重的世界性环境问题，多种重金属已经被国际癌症研究机构定为人类致癌物质。申请人在本项目基金的资助下，建立了质谱探针标记技术结合质谱分析方法，探索了重金属诱导的细胞表观遗传修饰动态变化及其机制。项目通过建立质谱探针标记以及色谱-质谱联用技术，（1）实现了核酸修饰高灵敏定性、定量分析，发现DNA中N6-羟甲基腺嘌呤修饰、RNA中N2-羟甲基鸟嘌呤修饰、mRNA中5-甲基尿嘧啶修饰；（2）探索了重金属砷、镉、铬和锑对小鼠胚胎干细胞DNA与RNA中5-甲基胞嘧啶（m5C）、5-羟甲基胞嘧啶（hm5C）、5-醛基胞嘧啶（f5C）、以及5-羧基胞嘧啶（ca5C）的影响，发现重金属胁迫造成三羧酸循环中的代谢物变化，从而导致Tet蛋白酶活性降低，并造成hm5C、f5C和ca5C的含量显著下降，从表观遗传修饰角度揭示了重金属的细胞毒理机理；（3）发现植物受到重金属镉胁迫会引起mRNA帽子及内部N7-甲基鸟嘌呤修饰（m7G）含量下降，且与m7G去帽酶的表达相关，显示了m7G修饰在应对重金属胁迫方面具有一定作用。申请人完成了项目拟定的研究计划，在项目的资助下，发表30篇SCI论文（29篇通讯作者，1篇第一作者），主要包括Nucleic Acids Res、Chem Sci（3篇）、CCS Chem、ACS Chem Biol（3篇）、Anal Chem（7篇）、Chem-Eur J等。授权专利2项。