E3泛素连接酶HECTD3修饰MALT1在小鼠T细胞免疫系统中的功能初探
文献类型：学位论文
| 作者 | 陈曦 |
| 学位类别 | 硕士 |
| 答辩日期 | 2014-11 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 陈策实 |
| 关键词 | HECTD3 蛋白质泛素化 NF-κB 免疫系统 肿瘤免疫 |
| 其他题名 | The role of the E3 ligase HECTD3 modify MALT1 in mouse T cell immune system |
| 中文摘要 | 蛋白质泛素化广泛存在并调节细胞的多种生理功能。它是一个3步的酶联反应，由三种酶催化进行，E1泛素激活酶、E2泛素结合酶、E3泛素连接酶，泛素分子通过E1、E2的催化激活，最后由E3将泛素分子转运至特异的底物，所以E3泛素连接酶决定了整个过程的特异性。泛素分子可以在底物上以不同的链接形式延长，形成不同类型的多聚泛素化链，不同的多聚泛素化链赋予了底物蛋白不同的命运。我所研究的HECTD3是一个E3泛素连接酶，它被证明可以泛素化MALT1，并且增加MALT1的稳定性，调节肿瘤细胞的耐药性，那么这种修饰对MALT1自身功能的发挥有何影响，HECTD3是以何种链接形式、在什么位点泛素化MALT1还没能够阐述清楚。 很多研究显示，蛋白质泛素化和免疫系统息息相关，免疫系统中一个非常重要的通路，NF-κB信号通路中有很多步骤都是由蛋白质泛素化驱动调节的，当刺激信号刺激细胞，胞内信号会促使上游激酶磷酸化激活IKK复合体，活化的IKKβ能够磷酸化IκBα，并且经过蛋白质泛素化过程，再经泛素蛋白酶体识别IκBα上带有的降解信号，将其降解，释放出游离的p50/p65复合体，被转运入核，结合到DNA上，启动基因转录。NF-κB转录因子主要调控了炎症相关基因和抗凋亡基因的转录，由于MALT1是TCR/BCR信号激活NF-κB通路当中的一个关键蛋白，那么HECTD3对MALT1的泛素化调节是否会影响NF-κB信号的激活，HECTD3是否参与了机体免疫系统的调节值得深入研究。 研究过程中，我们发现，HECTD3并不影响MALT1的蛋白酶活性，并不影响IL-1β、TNFα、LPS激活NF-κB。不能抑制TCR介导的NF-κB活化。发现在HECTD3缺失的淋巴细胞中，TCR信号激活NF-κB后，多种细胞因子的水平上升，其中包括免疫系统中重要的IL-2、IFNγ等。提示HECTD3参与了免疫系统的应答过程，并且调控多种细胞因子的分泌。这个发现可能和小鼠EAE疾病的发病、肿瘤的发生发展相关。HECTD3在免疫系统中的功能和机制还需要进一步的深入研究。 |
| 英文摘要 | Ubiquitination is widely emerging in regulating many cell signaling pathway. It is a three-step enzymatic reaction catalyzed by three different types of proteins, termed E1 Ubiquitin-activating enzymes, E2 Ubiquitin-conjugating enzyme, and E3 ubiquitin ligases. An E1 first activate the ubiquitin molecule, the activated ubiquitin is transferred to an E2 . The E2-ubiquitin complex can interact with E3 ubiquitin ligase, then transfer the ubiquitin to the lysine on substrate protein. E3 ligases act as a key role in ubiquitin transfer process by recognizing specific protein substrates. The polyubiquitin chains can linked in different type, then formed many different kinds of polyubiquitin chains, which determine the different fate of the substrate. In my study, HECTD3 is a E3 ubiquitin-ligase, It can increase MALT1 ubiquitination and stabilize MALT1 protein level, so that HECTD3 promotes cancer cell survival. In this study, we want to determine how HECTD3 promotes MALT1 ubiquitination, in which site and by which type of the polyubiquitin chains. Many previous studies indicate that ubiquitination plays important roles in regulating a variety of signals in immune system. In NF-κB pathway, many steps are driven by ubiquitination. When cells received the stimulate signals, the intracellular signals can promote the phosphorylation and activation of the IKK complex. Activated IKKβ phosphorylates IκBα and targets it for degradation via the proteasome, then the p50 and p65 subunits of NF-κB are released and translocated into the nucleus to bind to DNA to activate gene transcription. The NF-kB target genes are critical regulators of proinflammatory and antiapoptotic . As the key component in TCR/BCR mediated NF-κB signaling, we wondered if HECTD3 also have some functions in immune system. In this study we found that HECTD3 didn’t affect MALT1’s procaspase activity, and we use IL-1β、TNFα、LPS to activite the NF-κB pathway, we didn’t see any difference between HECTD3 wildtype MEF (HECTD3+/+) and HECTD3 knockout MEF(HECTD3-/-). But when we activite the TCR signaling pathway in lymphocyte ,we saw many cytokine increased in HECTD3 depletion cell, include IL-2 and IFNγ. These results indicate HECTD3 play a negative role in NF-κB signaling pathway, regulate many cytokine’s expression and secretion. These foundings maybe connected with EAE model and tumor immunology. The exact function and mechanism of HECTD3 in the Immune System require futher investigation. |
| 语种 | 中文 |
| 源URL | [http://159.226.149.26:8080/handle/152453/10088]  |
| 专题 | 昆明动物研究所_肿瘤生物学 |
| 作者单位 | 中国科学院昆明动物研究所 |
| 推荐引用方式 GB/T 7714 | 陈曦. E3泛素连接酶HECTD3修饰MALT1在小鼠T细胞免疫系统中的功能初探[D]. 北京. 中国科学院研究生院. 2014. |
入库方式： OAI收割
来源：昆明动物研究所
浏览0
下载0
收藏0
其他版本
除非特别说明，本系统中所有内容都受版权保护，并保留所有权利。