TLR4-miR-351-IL-11通路在辐射防护中的作用和机制研究

研究电离辐射损伤防治具有重要理论和实用科学价值。我们前期研究证明TLR4具有显著的辐射防护作用，然而目前关于TLR4辐射防护作用的分子机制仍不十分清楚,制约了其向应用研究的发展。课题组在TLR4辐射防护作用分子机制方面进行了探索研究，筛选出辐射条件下TLR4 KO小鼠相关差异最显著的miRNA miR-351和细胞因子IL-11，初步发现miR-351可靶向抑制IL-11信号通路。在此基础上提出TLR4→miR-351→IL-11通路可能在TLR4辐射防护中发挥关键作用的科学假设。本项目拟从分子、细胞、组织和体内多层次进行系统实验研究，揭示上述三个重要分子之间的相互关系，探讨它们与TLR4辐射防护作用之间的内在联系；阐明TLR4-miR-351-IL-11通路在辐射防护中的具体作用及其分子机制，从而证实我们的假说，为电离辐射损伤防治研究提供新的理论和实验基础，为辐射防护寻找新靶点和新途径。

The study of radioprotection for medical and bio-defense applications are of greatest importance. To develop effective therapeutic drug requires the elucidation of the underlying mechanisms of radioprotection..Our previous study proved that TLR4 played an important role in radioprotection. We found that mice deficient in TLR4 were more susceptible to IR-induced mortality and morbidity. LPS, which activated TLR4 in vivo, induced radio-resistance. Moreover, TLR4 in vivo ligands are required for basal radio-resistance. However, the underlying molecular mechanism of TLR4 mediated radioprotection is not clear yet. In this project, we try to study the underlying molecular mechanism in depth. We have constructed the TLR4 mediated radioprotection model in vitro and in vivo by using TLR4 overexpression cell lines and TLR4 KO mice. To identify the potential molecules involved in TLR4 mediated radiation resistance, we have compared the cytokines and miRNAs profiles before and after radiation in TLR4 KO mice and WT mice. We found that IL-11 was up-leveled by TLR4 mostly and miR-351 was inhibited by TLR4 mostly. Significantly, we found miR-351 could inhibit IL-11 expression by 3'UTR dependent way, and inhibited STAT3 and NF-κB, the transcriptional factors of IL-11..Based on previous data, we proposed our hypothesis: TLR4-miR-351-IL-11 pathway played a critical role in TLR4 mediated radioprotection. .To completely confirm this hypothesis, we intended down or up-regulated miR-351 in vivo or in vitro by plasmid transfection, adenovirus vector and miR-351 KO mice to identify the role of miR-351. Similarly, we tried to study the role of IL-11 by using recombination IL-11, IL-11 over- and down-expression vector and IL-11 KO mice. As we have proved that miR-351 could target IL-11, we next tried to study the regulation effect of miR-351 to the IL-11 signal pathway, and by which way miR-351 and IL-11 participated in radiation resistance..Applicant has been focusing on the radioprotection effect of TLR4 and its underlying molecular mechanism for several year and have a lot of experience in radiobiology study. This is a probe study and is the first time to study the role of miR-351 in radioprotection, and to construct the miR-351 KO mice. We believe that, if funded, with our professional efforts and functioned-well lab, this project would elucidate the underlying mechanism of TLR4-miR-351-IL-11 mediated radioprotection. If successful, our study would contribute a better understanding in radiobiology, and favor the development of novel radioprotective drugs.