Cbl-b通过泛素化降解SHP2进而阻止HOXA10入核抑制T细胞活化的作用及分子机制研究

T细胞活化的分子调控一直是免疫学研究的热点问题，有报导认为Cbl-b抑制T细胞活化，但具体分子机制还不甚清楚。我们现有的预实验结果发现Cbl-b缺失后导致miR-99a和miR-125b表达升高，且过表达miR-99a或miR-125b均可增强T细胞活化。进一步研究发现在T细胞活化状态时，Cbl-b和SHP2结合并泛素化SHP2，敲除SHP2后，T细胞活化被显著抑制。Western-blot结果显示SHP2可以去磷酸化HOXA10，Cbl-b缺失T细胞在抗CD3抗体单独刺激情况下HOXA10就可以入核，荧光霉素报告实验证明HOXA10可以调控miR-99a/miR-125b的表达。本课题拟在现有预实验结果上进一步通过细胞、分子生物学方法和Cbl-b、SHP2、HOXA10敲除小鼠深入研究Cbl-b抑制T细胞活化的分子机制，为T细胞活化调控提供新的解释，为自身免疫和肿瘤免疫治疗提供新的思路。

The molecular regulation of T cell activation has always been a hot topic in immunology. It has been reported that Cbl-b inhibits T cell activation, but the specific molecular mechanism is not very clear so far. Our preliminary experiments showed that the ablation of Cbl-b resulted in the increased expression of mir-99a and miR-125b, and the overexpression of mir-99a or miR-125b could enhance T cell activation. Further study found that Cbl-b could bind SHP2 in the activated T cell and ubiquitinate SHP2. The activation of SHP2 deficient T cell was significantly inhibited. Western blot showed that SHP2 could dephosphorylate HOXA10, and HOXA10 could enter the nucleus under the stimulation of anti-CD3 antibody alone in Cbl-b deficient T cells.Luciferase report assay showed that HOXA10 could regulate the expression of mir-99a / miR-125b. In this project, we intend to further study the detailed molecular mechanism of Cbl-b inhibiting T cell activation through cell biology, molecular biological methods and Cbl-b, SHP2, HOXA10 knockout mice model . We do believe this research will provide a new explanation for the regulation of T cell activation and a new idea for autoimmune disease and tumor immunotherapy.