转录因子WT1异常表达在寻常型银屑病皮损形成中的作用及机制研究

The mechanisms of psoriasis vulgaris remain unknown, characterized by abnormal keratinocytes proliferation and apoptosis. Transcription factor WT1 plays important role in many pathophysiologic processes such as organs development and tumorigenesis. Our studies suggested that the expression of WT1was increased significantly in skin lesions from psoriasis vulgaris compared with normal controls. In addition, the genomic DNA methylation level and DNMT1 expression level were also increased significantly in psoriasis vulgaris lesions. According to many publications, WT1 can promote tumor cells proliferation through recruiting DNMT1 to target genes, which inducing hypermethylation and down-regulation of target genes. Moreover, many studies suggested that the expression of WT1 can be regulated by microRNAs. Our project will identify the role of WT1 in regulating keratinocytes proliferation and skin lesions of psoriasis vulgaris in vitro and in vivo. Furthermore, we will investigate the cause of WT1 up-regulation in skin lesions of psoriasis vulgaris patients (microRNA regulation) and the mechanisms of keratinocyte proliferation induced by increased WT1 expression (regulation of methylation status in downstream target gene promotor). This project will be helpful in revealing the pathogenesis of psoriasis vulgaris and will provide a novel target for psoriasis treatment.

角质形成细胞异常增殖和凋亡是寻常型银屑病显著的病理特征，并参与银屑病特征性皮损形成，但其具体机制尚未阐明。转录因子WT1在器官发育、肿瘤形成等病理生理过程中发挥重要作用。本课题组前期研究发现，与正常皮肤组织相比，寻常型银屑病患者皮损区WT1表达明显增高。此外，我们还发现银屑病患者皮损区整体DNA甲基化水平明显增高，DNMT1表达水平升高。文献报道称，WT1可通过招募DNMT1使靶基因发生高甲基化，从而发挥其促进肿瘤细胞增殖的作用，且其自身可受到microRNA的调控。本课题拟通过细胞及动物实验，阐明转录因子WT1在调控角质形成细胞增殖凋亡及寻常型银屑病皮损形成中的重要作用。在此基础上初步探讨WT1表达升高促进角质形成细胞增殖的机制（调控下游靶基因启动子区甲基化状态)以及银屑病皮损中WT1表达升高的机制（microRNA调控)。本项目将有助于进一步阐明银屑病的发病机制，并为其治提供新靶点。

银屑病是一种常见的复发性炎症性皮肤病。炎症细胞浸润和角质形成细胞过度增殖是其组织病理学的基础，但其机制尚未被阐明。转录因子WT1在许多肿瘤中过表达，并促进肿瘤生长，发挥致癌作用。既往研究发现，与正常皮肤组织相比，寻常型银屑病患者皮损中WT1表达明显升高,且WT1促进角质细胞增殖。本研究旨在阐明转录因子WT1促进银屑病皮肤损伤的机制。我们采用Lipofectamine®2000对HaCaT细胞内WT1进行稳定过表达或抑制，利用RNA -seq对实验组和空白对照组的差异表达基因进行筛选；利用Chip-seq和荧光素酶报告基因筛选验证WT1与靶基因的结合，利用Chip-qPCR研究WT1调控靶基因的机制。结果显示：结合转录组测序和生物信息学分析,两组之间IL-1β和IL-1α的表达有显著差异；过表达WT1后，IL-1的mRNA和蛋白水平明显升高，而干扰WT1表达后，IL-1的表达水平显著下降；荧光素酶报告基因实验证实了IL-1可能为WT1的靶基因。本研究为银屑病的治疗提供新的靶点和思路。