RASSF1A通过Hippo-YAP信号通路调控银屑病表皮异常增殖的研究

Psoriasis is a chronic inflammatory skin disease. The keratinocyte-mediated inflammation is pivotal in the pathogenesis of psoriasis, although its detailed mechanism remains unclear. Our previous studies showed that the expression of Yes-associated protein (YAP) is upregulated in psoriatic skin, and YAP participates in the regulation of the proliferation and apoptosis of keratinocytes. RAS-association domain family 1A (RASSF1A), a negative upstream regulator of YAP, is down-regulated in psoriatic skin, so it is speculated to be important in the pathogenesis of psoriasis. Therefore, the purposes of this study are: ①To elucidate the methylation of RASSF1A gene as well as the its correlation with the expression of YAP in psoriatic skin; ②To reveal the RASSF1A regulation of phosphorylation of the core parts of kinase cascade in Hippo-YAP signaling pathway in vitro, which may affect the key biological processes including proliferation and apoptosis of keratinocytes under psoriatic microenvironment; ③To verify the hypothesis by using the imiquimod-induced psoriatic murine model, and also to design certain approaches to reverse the methylation of RASSF1A, which may delay the progression of skin lesions in this model. The results from this study will contribute to the elucidation of the mechanism of RASSF1A-Hippo-YAP pathway underlying the epidermal abnormal proliferation of psoriasis, and provide novel therapeutic target in the treatment of psoriasis.

银屑病是一种慢性炎症性皮肤病，角质形成细胞（KC）炎症反应参与其发病机制，但具体机制尚不清楚。申请人前期研究发现，Yes相关蛋白（YAP）在银屑病皮损中高表达，并通过调控KC的增殖、凋亡等参与发病过程，RAS相关结构域家族1A（RASSF1A）在银屑病皮损中表达降低，作为YAP上游负性调控因子，推测其可能在银屑病发病机制中发挥重要作用。本课题拟：①检测RASSF1A在银屑病中的甲基化情况，并分析其与YAP表达的相关性；②体外细胞实验证实RASSF1A可通过调控Hippo-YAP信号通路激酶相关因子磷酸化，从而影响银屑病炎症微环境下KC增殖、凋亡等生物学过程；③用银屑病小鼠模型验证上述结论，并设计逆转RASSF1A甲基化水平技术，来延缓银屑病皮损的进展。本课题对于揭示RASSF1A-Hippo-YAP信号通路在银屑病表皮异常增殖中的作用机制有重要意义，有望为寻找银屑病治疗的新靶点提提供思路。

背景：.银屑病是一种慢性炎症性皮肤病，角质形成细胞炎症反应参与其发病机制，但具体机制尚不清楚。申请人前期研究发现，Yes相关蛋白（YAP）在银屑病皮损中高表达，并通过调控角质形成细胞的增殖、凋亡等参与发病过程，RAS相关结构域家族1A（RASSF1A）在银屑病皮损中表达降低，作为YAP上游负性调控因子，推测其可能在银屑病发病机制中发挥重要作用。.主要研究内容：.本项目检测RASSF1A在银屑病中的甲基化情况，并分析其与YAP表达的相关性，并通过银屑病小鼠模型及细胞模型检测抑制RASSF1A甲基化或使其过表达后对YAP表达、细胞增殖、细胞周期、凋亡、炎症细胞因子及相关信号通路活性的影响。.重要结果及关键数据：.研究结果发现，银屑病皮损中RASSF1A的甲基化程度升高、表达降低，银屑病细胞模型或动物模型中加入甲基化抑制剂5-Aza-CdR或感染慢病毒使其过表达后，YAP表达降低，同时可以抑制细胞增殖、G0/G1期细胞周期阻滞、凋亡率增加、炎症细胞因子（IL-1β、IL-6、IL-17和IL-23）表达下降、AKT、ERK、STAT3及NF-κB信号通路活性降低，银屑病小鼠模型的皮损好转。.科学意义：.通过本项目的研究结果推断出在银屑病中，RASSF1A可通过抑制YAP的表达发挥抑制细胞增殖、诱导凋亡、改善炎性因子的表达等作用，本项目对于揭示RASSF1A-YAP通路在银屑病表皮异常增殖中的作用机制有重要意义，研究药物抑制RASSF1A甲基化水平有望用于银屑病的治疗。