潘氏细胞调控肠道干细胞DNA辐射损伤修复能力的机理研究

The epithelium mucosa of the small intestine is the fastest self-renewing tissue fueled by a population of intestinal stem cells (ISCs). The studies focused on the ability of ISCs to regenerate damaged mucosa following radiation have drawn extensive attention in the field of radiation medicine. Our previous studies showed that Lgr5+ ISCs sandwiched between Paneth cells repair DNA damage significantly more efficiently than other populations of cell in crypt. However, little is known about the mechanisms involved in this regulation. ISC activities and repair function are strictly regulated by stem cell niche. Accumulating evidence show that Paneth cells, a key constituent of the ISC niche supplying essential factors，play a key role in regulation of the self-renewal and function of ISCs. In this study, Using multiple transgenic mouse models ( Lgr5 transgenic mice and Paneth cell-deficient mice ) and 3D intestinal stem cell culture system, our goal is to determine the contribution of Paneth cell to the regulation of DNA repair capacity in ISCs including how Paneth cells and their growth factors orchestrate the DNA damage responses (DDR) in ISCs, as well as the DDR in "+4 stem cells". This project will help us better understand of the roles of Paneth cell in regulation of the DDR in ISC, which are crucial to develop efficient radiotherapeutic strategies to protect ISCs, as well as identification of radioprotetors specicically tailored to protect intestinal stem cell post irradiation.

肠道干细胞是小肠粘膜快速更新和辐射损伤修复的源泉，一直以来是放射医学研究的重点。申请人前期的工作发现相对于隐窝内其它上皮细胞，位于潘氏细胞中间的Lgr5+干细胞具有快速修复DNA辐射损伤的能力，但对其具体的机制知之甚少。Lgr5+干细胞的干性维持以及损伤修复离不开周围的微环境调控。最新的研究表明作为微环境重要组成的潘氏细胞能够分泌各种干细胞生长因子以维持干细胞的功能。本课题将利用多种转基因小鼠模型（Lgr5转基因小鼠和潘氏细胞敲除小鼠）及体外干细胞3D培养体系，系统地研究潘氏细胞对干细胞DNA 损伤修复反应的调控，包括其分泌的各种生长因子对干细胞DNA 损伤修复反应的影响、以及与潘氏细胞相邻的“+4位置干细胞"的DNA 损伤修复反应。本课题将阐明潘氏细胞对肠道上皮干细胞DNA修复能力的调控机理，从而为指导开发更有效的干细胞辐射保护剂提供理论基础。

放射性肠炎主要诱因源于辐射造成粘膜上皮干细胞损伤和再生障碍，与干细胞周围的微环境变化密切相关。作为微环境重要组成的潘氏细胞能够分泌各种干细胞生长因子以维持干细胞的功能。项目通过利用多种转基因小鼠模型及体外干细胞3D培养体系，系统地研究潘氏细胞及周围微环境对干细胞参与修复的调控，包括干细胞微环境特性性表达基因，各种分泌的生长因子对干细胞损伤修复反应的影响。项目研究发现Bach2基因是肠道干细胞微环境特异性基因，在干细胞和潘氏细胞高表达；Bach2基因通过调控辐射后隐窝上皮干细胞和子代细胞的DNA修复从而进一步影响肠道隐窝辐射后再生。研究发现DACH1基因在隐窝底部尤其潘氏细胞上特异性表达，是肠道隐窝底部特异性表达基因；DACH1能通过调控BMP信号通路影响肠癌的发生；本课题数据在干细胞微环境层面，尤其潘氏细胞特异性表达基因角度阐明了其对肠道上皮干细胞DNA修复能力的调控机理，从而为指导开发更有效的干细胞辐射保护剂提供理论基础。.在该项目的资助下先后在国际知名杂志Cell Stem Cell, Cancer Research, EBiomedicine，Protein&Cell, Carcigenesis, Stem Cell Reports等上发表研究工作，其中包括英文一区SCI研究论文6篇,2区2篇，其中发表在Cell Stem Cell上的研究论文被Web of Science评选为高被引用论文。依托肠道类器官为基础的抗辐射药物筛选平台成功筛选到多个抗辐射小分子化合物，建立了放射性肠炎和口腔炎小鼠药效评价模型。迄今授权发明专利4项。另外，在研究生培养上，申请人资助期内培养研究生5人；