TRIM52 lncRNA在T细胞中的功能及其机制研究

Long non-coding RNA is a kind of ubiquitously expressed non-coding RNAs, which is involved the regulation of in many aspects of cellular and physiological activities, including immune regulation. There are a few LncRNAs that have been reported to be involved in the immune response, however, it is unknown that how LncRNA regulates ubiquitination in T-cell. When we studied a novel ubiquitin E3 ligase TRIM52 specifically expressed in T-cells, we found there were lncRNA (Lnc-TRIM52-As) in the promoter region of TRIM52. Further study indicated that the expression of LncR-TRIM52-As was suppressed upon T-cell activation signal stimulation, meanwhile expression level of TRIM52 was reduced as well. Moreover, knocking down of LncRNA by siRNA was correlated with the down-regulation of TRIM52, suggesting the potential function of LncRNA-TRIM52-As on regulating TRIM52, therefor regulating T-cell function. Based on these solid preliminary findings, we propose to investigate the molecular mechanism of how Lnc-TRIM52-As regulates TRIM52 expression; and the function of TRIM52 per se on T-cell function. This study will provide the critical evidence to understand how the genomic information is processed and regulated during the T-cell activation, as well as the how the ubiquitination regulates T-cell function.

长链非编码RNA(LncRNAs)是近年来广受关注的一类大分子RNA,可调控多种重要的细胞生理活动,例如免疫调控等。虽然目前已经发现了多个 在免疫系统起调控作用的LncRNAs,但lncRNAs介导的T细胞泛素化调控相关研究较少。本课题组在研究T细胞内特异性高表达的泛素化E3连接酶TRIM52时，发现TRIM52启动区存在LncRNA (Lnc-TRIM52-As)。进一步实验表明,在T细胞活化后, 该LncRNA与TRIM52基因表达水平变化趋势高度一致,而且LncRNA敲低后,TRIM52基因表达也发生下调,提示该LncRNA可能通过调节TRIM52基因的表达,调节T细胞的功能。基于此,本课题组拟深入探讨Lnc-rim52-AS调节TRIM52的分子机制;以及TRIM52对T细胞功能和泛素化的调节作用和机制。本项目对于深入了解T细胞活化过程中遗传信息传递以及泛素化调控机制具有重要意义。

TRIM蛋白家族是主要的一个E3泛素连接酶家族。大多数TRIM分子有E3连接酶的功能，通过催化底物蛋白的泛素化来实现其信号通路调控作用。TRIM家族蛋白成员有很多都被证明在免疫反应中起调控作用，特别是在抗病毒固有免疫中起作用。此外，几年来研究表明TRIM家族在适应性免疫的调控中，特别是在T细胞发育和激活信号通路中，同样发挥重要作用。本课题通过生化、细胞和动物实验，研究了TRIM52、LncRNA-TRIM52 AS以及TRIM6X在T细胞功能中的作用。实验结果表明，TRIM52以及lncRNA-TRIM52 AS水平均受到TCR信号通路所抑制，在T细胞内敲低TRIM52能上调TCR信号通路活性。但在体内，TRIM52缺失不没有导致T细胞发育和功能的改变；提示TRIM52在体内、体外实验体系中的不同功能。此外，本课题还详细研究了TRIM6X在T细胞的功能，结果显示TRIM6X缺失虽然不影响T细胞的发育，但能显著增加效应记忆CD8+T细胞和中央记忆CD8+T细胞的比例。利用黑色素瘤模型以及单细胞测序等技术，我们验证了TRIM6X在耗竭性CD8T细胞内高表达，TRIM6X缺失，可抑制耗竭性CD8T细胞的产生，维持具有细胞杀伤活性的记忆T细胞表型，从而调节T细胞的抗肿瘤活性。机制研究表明，TRIM6X调节TGF-beta和IL-7/IL-15信号通路的AKT磷酸化，从而影响耗竭CD8+T细胞的发育。综上所述，本课题深入解析了泛素E3连接酶TRIM52和TRIM6X在T细胞功能和抗肿瘤免疫中的功能及其作用机制。