FOXO4的巯基亚硝基化修饰调控细胞衰老与凋亡信号相互转变的机理研究及其在衰老相关心血管疾病中的应用

血管内皮细胞衰老是衰老相关心血管疾病的关键致病因素，而p53介导的细胞凋亡是清除衰老细胞的重要途径。前期在血管内皮细胞衰老模型中我们发现FOXO4的Cys415位点存在S-NO修饰，并伴随FOXO4与p53在核内结合及启动p53介导的衰老信号。而Cys415位点突变可显著抑制FOXO4与p53结合，缓解衰老并激活细胞凋亡。因此，我们提出科学假设认为FOXO4的S-NO修饰是其与p53结合的分子基础，并构成内皮细胞衰老与凋亡转换的核心机制，但其分子机制仍待进一步阐明。我们将在前期基础上明确衰老细胞启动凋亡过程中FOXO4调控p53的机制；揭示p53与FOXO4结合所需结构域；并考察Cys415位点突变对衰老所致心血管疾病模型中血管功能的作用。本项目旨在分子水平深入阐述FOXO4的S-NO修饰调控细胞衰老与凋亡转换的核心机制，寻找清除衰老细胞的有效途径，为衰老相关心血管疾病的防治提供新靶点。

Endothelial cellular senescence is a key pathogenic factor of age-associated cardiovascular diseases, and p53-mediated apoptosis is the major approach to eliminate senescent cells. In the previous study, we observed a dramatic increase of nitrosylation on the Cys415 of FOXO4 in senescent endothelial cells, which facilitated the association between FOXO4 and p53 in the nuclear, resulting in the occurrence of senescence. The senescence-associated phenotypes were significantly alleviated by site-directed mutagenesis of Cys415. Concomitantly, FOXO4 disassociated from p53 in the nuclear, along with the initiation of apoptosis machinery. Based on these findings, we speculate that the S-nitrosylation is the molecular basis of the association between FOXO4 and p53, constituting the main mechanism of the switch from senescence to apoptosis. Therefore, we will firstly explore the mechanism of FOXO4 in switching p53 function from senescence to apoptosis. Secondly, the essential binding domain of p53 is to be revealed, followed by validation of its role in regulating cellular senescence, apoptosis and neo-vascularization. Finally, the efficacy of site-directed mutagenesis of FOXO4 Cys415 in the cardiovascular diseases is to be determined in natural aging and other cellular senescence-contributed diseases (atherosclerosis, diabetes, hypertention). This project aims to elucidate the mechanism of FOXO4 in switching p53 function from senescence to apoptosis, and explore effective approaches for the elimination of senescent cells. This project is expected to provide new targets for the prevention and treatment of age-associated cardiovascular diseases.