UBE2L3在银屑病发生发展及转归中的作用及机制研究

Psoriasis is a complex chronic, immune-mediated inflammatory skin disease characterized by erythematous and scaly plaques. Ubiquitin-conjugating enzymes UBE2L3, located at chromosome 22q11.2, is a member of the E2 ubiquitin-conjugating enzyme family. This enzyme is demonstrated to participate in the ubiquitination of p53, c-Fos, and the NF-κB precursor p105 in vitro. UBE2L3 is primarily known for its role in the cell cycle. Specifically, UBE2L3 manages cell cycle regulatory protein levels and involves in cell proliferation and immune function. Although UBE2L3 was one of the first E2 conjugating enzymes to have its structure determined, its cellular functions have remained largely unknown. Until now, only one paper identified a SNP polymorphisms in psoriasis determined by genome-wide association studies (GWAS). Our initial experiments on psoriatic skin have identified the depletion of UBE2L3 in the epidermis of psoriatic lesional skin. Therefore, we hypothesized that UBE2L3 may play a crucial role in the innate immunity and adaptive immunity of the skin. UBE2L3-mediated impairment of protein clearance is associated with the pathogenesis of psoriasis. Meanwhile, by investigating the skin from healthy human and psoriatic and chronic eczematous lesional skin, different expression pattern and function of UBE2L3 could be defined in the epidermal keratinocytes. Furthermore, depletion of UBE2L3 in psoriatic lesional keratinocytes is an initiation for onset of psoriasis or just an effector of cytokines, such as Th17 cytokines, from immune cells could also be clarified. I addition, the role of UBE2L3 in the cellular function of keratinocytes should also be determined. Finally, the role of UBE2L3 in the innate and adaptive immunity of skin and pathogenesis of psoriasis was identified by investigations on the skin of UBE2L3 knockout mouse. To increase UBE2L3 or giving exogenous humanized recombinant UBE2L3 may be promising therapy for psoriasis.

银屑病是免疫介导的慢性炎症性皮肤病，泛素结合酶E2L3 (UBE2L3)参与泛素化通路，在调控细胞功能和免疫中发挥重要作用。既往除GWAS研究发现UBE2L3一单核苷酸多态性位点与银屑病相关外，未检索到UBE2L3与银屑病发生发展相关的研究。我们在前期发现银屑病皮损UBE2L3表达缺失的基础上，提出UBE2L3可能调控皮肤固有免疫和适应性免疫，其介导的蛋白质清除障碍与银屑病发生发展相关。因此，我们拟通过研究银屑病、湿疹患者的皮损与健康人皮肤，发现UBE2L3在表皮角质形成细胞中表达的差异，阐明UBE2L3的缺失是导致银屑病的始动因素，还是银屑病表皮受细胞因子等调节的终末效应，明确UBE2L3在表皮角质形成细胞生物学功能中的作用及其靶标，并进一步通过对UBE2L3基因敲除小鼠模型的研究，探索UBE2L3在皮肤固有免疫和免疫细胞趋化中的功能，确立促进UBE2L3表达可能是治疗银屑病的有效方法。

根据UBE2L3在银屑病皮损中表皮的表达降低现象，探究其与银屑病角质形成细胞中Casp1激活之间的关系，发现Casp1的激活可以降低UBE2L3的表达，并且成功构建通通过UBE2L3敲低原代角质形成细胞，以及UBE2L3过表达的慢病毒。通过对IMQ诱导的小鼠银屑病样模型的研究，进一步确认在IMQ诱导的模型中，UBE2L3的降低只发生在表皮，且Casp1的激活也主要发生在表皮。我们的研究结果表明，UBE2L3在银屑病中以炎症体依赖性的方式在caspase-1激活和前IL-1β之间起联系作用。在银屑病皮损和角质形成细胞中观察到UBE2L3的下调，体外实验结果也表明UBE2L3的降低促进了IL-1β的产生。此外，我们的结果显示，在IMQ诱导的类银屑病小鼠模型中，表皮中IL-1β和成熟形式的Casp1（p45、p20或p10）分泌增加。而且，UBE2L3在小鼠中的过度表达下调了表皮中IL-1β的产生，而不是Casp1的产生。UBE2L3在减轻IMQ诱导的小鼠银屑病样炎症方面也发挥了重要作用。.通过loxp-cre的方法从而构建表皮UBE2L3敲除的转基因鼠，从免疫荧光染色、免疫组化染色、Western blots和RNA测序的方法从RNA水平和蛋白质水平上进行表皮特异性UBE2L3敲除小鼠的建立和验证。并且观察到小鼠有自发性皮损的现象。所以，Ube2l3在一个银屑病表皮发生发展过程中