尿嘧啶转移酶TUT4修饰miR-132/212调控放射性食管损伤的机制研究

Radiation-induced esophageal injury remains a limitation for the process of radiotherapy for lung and esophageal cancer patients. Esopheageal epithelial cells are extremely sensitive to irradiation, nevertheless, factors involved in the radiosensitivity of esopheageal epithelial cells are still unknown. Terminal uridyl transferase 4 (TUT4) could modify the sequence of miRNAs, which affect their regulation on miRNA targets and function. In our preliminary study, we demonstrated that TUT4 is closely associated with radiation-induced esophageal injury and that TUT4 affected the uridylation of miR-132/212. This project will utilize multiple molecular biological approaches to illustrate: 1) The role of TUT4 in esopheageal epithelial cell radiosensitivity and radiation-induced esophageal injury of animal models; 2) The mechanism of TUT4 in modification of miR-132/212 and influence of modified miR-132/212 on cell radiosensitivity; 3) The mechanism that how exosomes mediate miR-132/212 delivery into neighbouring cells. This project is likely to illustrate uridylation of miR-132/212 by TUT4 in modulating the radiosensitivity of esopheageal epithelial cells and contribute to our understanding of the novel mechanism of radiation-induced esophageal injury.

胸部肿瘤放疗引起的食管损伤是导致放疗中断乃至失败的重要原因。食管上皮细胞对电离辐射极为敏感，但其放射敏感性的影响机制尚不清楚。尿嘧啶转移酶TUT4能对特定miRNA进行末端尿嘧啶修饰，影响miRNA对靶基因的调控及功能。我们前期在细胞水平和TUT4敲除小鼠中发现TUT4与放射性食管损伤密切相关，且能改变miR-132/212的末端修饰。本项目拟通过多种分子生物学手段在细胞水平和动物水平阐明：1）尿嘧啶转移酶TUT4对食管上皮细胞放射敏感性及动物模型放射性食管损伤的影响；2）TUT4对miR-132/212进行末端修饰的分子机制以及尿嘧啶修饰的miRNA对靶基因及食管上皮细胞放射敏感性的影响机制；3）受照食管上皮细胞通过通过外泌体途径运输修饰后miR-132/212对邻近细胞生物学行为的影响。本研究有望从尿嘧啶转移酶TUT4调控miRNA修饰的角度揭示影响食管上皮细胞放射敏感性的新机制。

食管上皮细胞对电离辐射极为敏感,胸部肿瘤放疗引起的食管损伤是导致放疗中断乃至失败的重要原因。尿嘧啶转移酶TUT4能对特定miRNA进行末端尿嘧啶修饰，影响miRNA对靶基因的调控及功能。我们在细胞水平和TUT4敲除小鼠中发现TUT4与放射性食管损伤密切相关，且能改变miR-132/212的末端修饰。下调TUT4表达可使miR132/212表达增加，miR132/212+UUU表达减少；过表达miR132/212可增加HEEC的放射敏感性，过表达miR132/212+UUU可减少HEEC的放射敏感性；下调TUT4表达且过表达miR132/212时细胞较单纯下调TUT4表达增殖能力更差，下调TUT4表达且过表达miR132/212++UUU时细胞较单纯下调TUT4表达增殖能力更强.X射线可增加HEEC中TUT4的表达，TUT4可降低HEEC放射敏感性、减轻放射损伤，其机制与miR132/212的尿苷化相关。受照食管上皮细胞通过通过外泌体途径运输修饰后miR-132/212对邻近细胞生物学行为的影响。