泛素E3连接酶Trim35靶向RelB降解在弥漫大B细胞淋巴瘤中的机制研究

The non-canonical NF-κB pathway plays a critical role in the development of diffuse large B-cell lymphoma (DLBCL),in addition, this pathway also reduces the sensitivity of DLBCL cells to chemotherapy via inducing anti-apoptotic gene expression. In cytosol, NIK and IKKα-meidiated p100 processing to p52 is believed to be the main regulatory mechanism for this pathway. However, how the non-canonical NF-κB pathway is modulated in nuclear is poorly understood. Our preliminary studies indicated that E3 ligase Trim35 was downexpressed in DLBCL tissues. Overexpreesion of Trim35 in DLBCL cells inhibited cell proliferation. Through a proteomic approach to screen Trim35-interacting proteins, we found that Trim35 interacted with RelB and promoted the ubiquitination of RelB. Furthermore, overexpression of Trim35 accelerated the degradation of RelB through proteasome pathway.In addition,we found the activation of the non-canonical NF-κB pathway also induced the ubiquitination of RelB. According to these data, we hypothesize that Trim35 regulates the non-canonical NF-κB pathway through targeting RelB for degradation in nuclear, which in turn affects the development and treatment of DLBCL. To test this hypothesis, cultured cancer cells, mouse model and the histological analysis of cancer tissue sections will be applied to investigate the role of Trim35 in the non-canonical NF-κB pathway and the development of DLBCL through targeting RelB for degradation, as well as its involvement in the chemotherapy.

非经典NF-κB通路在弥漫大B细胞淋巴瘤（DLBCL）发生中具有重要作用，并通过促进抗凋亡靶基因的表达导致DLBCL对化疗不敏感。在细胞浆内NIK和IKKα介导p100加工为p52被认为是非经典NF-κB通路的主要调控方式。然而，非经典NF-κB通路在核内的调控机制目前尚不清楚。我们的结果显示在DLBCL中E3连接酶Trim35低表达，Trim35抑制DLBCL细胞增殖。Trim35和RelB结合并促进RelB发生泛素化和降解，此外当非经典NF-κB通路激活时会促进RelB的泛素化。据此我们推测：E3连接酶Trim35通过靶向RelB在核内负调控NF-κB非经典通路从而影响DLBCL的发生发展与治疗。本课题将探讨Trim35靶向RelB降解调控非经典NF-κB通路和DLBCL的机制，我们还将评估在Trim35低表达的DLBCL细胞中靶向非经典NF-κB通路对于化疗疗效的影响。

泛素系统在细胞内维持稳态起到重要作用，参与细胞信号转导、细胞周期、增殖、凋亡、炎症、免疫等多种生命活动的调控。Trim35 作为 Trim蛋白家族中的一员，是一种泛素 E3 连接酶，在肿瘤发生发展、治疗反应中起到关键作用。本项目中，我们发现Trim35 低表达与肺癌和弥漫型大B淋巴瘤患者不良预后相关，并且Trim35 可以明显抑制肿瘤细胞的增殖。机制上，Trim35 通过促进 RelB 发生 K63 泛素化，激活 NF-κB 非经典途径，同时可以介导 TAK1 调控 NF-κB 的经典通路， Trim35还通过介导 TAK1 调控肿瘤免疫微环境，影响多种促癌细胞因子的表达。另一方面，Trim35过表达可以抑制 DLBCL 细胞增殖并与 DLBCL 患者的较差生存相关，在DLBCL中Trim35 作为 E3 连接酶发挥作用，介导 CLOCK 的泛素化和降解，这也是DLBCL 中的 NK 细胞浸润的部分原因。. 综上，本项目主要探讨了Trim35介导RelB、TAK1以及CLOCK对肿瘤发展的重要作用，深入阐明了Trim35调控肿瘤的分子机制和对肿瘤治疗和预后的重要作用，研究加深了我们泛素-蛋白酶体降解系统的理解，为肿瘤的临床治疗供了新靶点、新策略。