端粒体系的端粒外作用参与非再生组织衰老- - TRF2调控神经特异性蛋白PPP2R2C延缓神经细胞衰老的机制

How telomeric components are implicated in the cellular senescence of non-dividing cells are not clear. We have found that telomeres have extra-telomeric effect and it might be responsible for the ageing of non-generative tissues. Our previous results showed that telomere replicative protein 2 (TRF2) binds to interstitial telomereic sequence (ITS) and exhibits extra-telomeric effect, including transcriptional regulation of the expression of neural specific protein PPP2R2C, dephosphorylation modification of DNA damage proteins and elongation of cellular life. In this project,we will study how the extra-telomeric effect is involved in the ageing of non-generative organs based on neural tissues: 1)in-vivo and in-vitro study whether TRF2 relieves DNA damage effect on neural cells through transcriptional regulation of PPP2R2C with the cell model expressing Aβ and Alzheimer's mouse model;2) we will establish a neural cell model expressing Tau, then study how TRF2 regulates phosphatase through regulating PPP2R2C, which will remove the deposition of abnormal proteins, for example p-Tau and extend cell longivity;3) we will focus on the role of TRF2 and PPP2R2C in the stemness and tissue repair. This project will elucidate whether telomeric components contain an extra-telomeric function which is a non-canonical signaling pathway in the protection against the degeneration of non-generative tissues,like neural tissues and faciliating tissue repair. In general, this project will contribute to the screening of senescence markers, prevention of organ fibrosis and the treatment of degenerative diseases.

端粒如何影响非分裂细胞衰老是一备受争议的论题。我们发现端粒存在端粒外作用，参与非再生组织衰老的新机制。前期研究证明端粒蛋白TRF2结合间质性端粒，发挥端粒外作用：转录调控神经特异蛋白PPP2R2C表达，去磷酸化修饰DNA损伤蛋白，延缓细胞衰老。本课题以神经组织为对象，探索端粒外作用参与非再生组织衰老的机制：⑴用表达Aβ的细胞和阿尔兹海默病小鼠模型，体内外研究TRF2调控PPP2R2C能改善神经细胞对DNA损伤的敏感性；⑵构建表达Tau蛋白的模型，研究TRF2调控PPP2R2C磷酸酶活性，清除异常蛋白堆积，延缓神经细胞衰老；⑶用神经干细胞和基因敲除斑马鱼模型，研究TRF2和PPP2R2C在干细胞功能和组织修复的作用。本项目将阐明端粒体系在非再生器官存在端粒外非经典通路，配合复制衰老的经典通路，延长细胞寿命，促进干细胞功能和组织修复。这是端粒调控衰老的新机制，为预防和治疗退行性疾病提供新思路。

我们运用表达Aβ（淀粉样蛋白，β-Amyloid）的神经细胞模型和转基因的Alzheimer’小鼠模型，构建表达Tau蛋白的神经细胞模型，运用神经干细胞模型和基因敲除斑马鱼模型(TRF2+/-、TRF2-/-和PPP2R2C-/-)，研究端粒体系的端粒外作用如何调控干细胞功能和组织修复作用。我们从体内外证明TRF2调控PPP2R2C的磷酸酶活性，证明端粒组件TRF2发挥端粒外作用，保护神经细胞的分子机制。我们研究立足于端粒组件TRF2的端粒外作用，转录调控神经系统特异性表达蛋白PPP2R2C，结果发现TRF2+/-和PPP2R2C+/- 、PPP2R2C-/-有相似的发育异常和早衰表型，过表达PPP2R2C可以补救TRF2缺失介导的神经元丢失和神经发育异常，提示PPP2R2C是TRF2调控神经发育和再生的下游关键因子，其调控机制为特异性结合ITS 转录调控PPP2R2C的表达。该项研究证明，TRF2等端粒体系存在组织特异性的转录重编程的端粒外功能，介导独立于其保护染色体末端的“复制衰老”经典通路、适用于特定组织的抑制器官衰老的非经典途径。端粒体系介导端粒外非经典途径，可以延缓神经细胞衰老和神经组织退行病变。.课题执行期间已发表标注本项目的通讯/并列通讯SCI 文章5篇（通讯），非通讯非第一作者文章1篇。培养及参与培养硕士研究生已毕业5名，博士研究生8名（6名在读，2名毕业），博士后1名(在站)。获得国家专利一项。此外，本课题的主要研究成果，正在投稿国际影响力的杂志上（SCI>10）论著1篇，准备投稿2篇。

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