m6A甲基转移酶WTAP在寻常型银屑病角质形成细胞异常增殖凋亡中的作用及机制研究

Abnormal proliferation and apoptosis of keratinocytes are the primary pathological changes of psoriasis vulgaris. Although the specific molecular mechanism is still unclear, the epigenetic mechanism has been demonstrated to play important roles. As a dynamic reversible chemical modification with the most abundant content in mRNA, m6A has become a hot topic of current epigenetic research. Evidence showed that m6A modification could mediate the proliferation and apoptosis changes of keratinocyte induced by arsenite. However, its role and mechanism in psoriasis vulgaris has not been reported. Our previous experiments found that both the m6A level and the expression of WTAP, a regulatory component of methyltransferase complex, were significantly upregulated in skin lesions of patients with psoriasis vulgaris. Inhibition of WTAP expression by siRNA significantly reduced the m6A level in HaCaT cells and promoted cell apoptosis. Therefore, we proposed a new hypothesis that WTAP might regulate the aberrant proliferation and apoptosis of keratinocytes via modulating the mRNA m6A level and expression of a certain target gene, thereby affecting the formation of psoriasis vulgaris lesion. Our project will elucidate the role and mechanism of WTAP in regulating keratinocyte proliferation and apoptosis in psoriasis vulgaris, as well as its effect on the formation of psoriasis-like skin lesions in mice through in vivo and in vitro experiments. This project will help to further clarify the pathogenesis of psoriasis vulgaris and will provide theoretical basis for finding novel targets to treat psoriasis.

角质形成细胞异常增殖凋亡是寻常型银屑病主要的病理改变，其具体分子机制不明，表观遗传机制在其中发挥重要作用。m6A作为mRNA上含量最丰富的一种动态可逆的化学修饰，成为当前表观遗传学研究热点。研究证实，m6A修饰可介导亚砷酸盐诱导的角质形成细胞增殖凋亡改变，然而其在寻常型银屑病中的作用及机制尚无报道。我们前期研究发现寻常型银屑病皮损中m6A水平显著升高，且其甲基转移酶复合物成份之一WTAP的表达亦显著增高。抑制WTAP的表达可降低HaCaT细胞中m6A水平，并促进细胞凋亡。由此，我们提出WTAP可能通过调控某靶基因mRNA的m6A水平及表达来调控角质形成细胞异常增殖及凋亡，进而影响寻常型银屑病皮损形成的全新假说。本课题拟通过体内外实验阐明WTAP调控寻常型银屑病角质形成细胞异常增殖凋亡的分子机制及其对银屑病样小鼠皮损形成的影响。该研究将有助于阐明银屑病发病机制，为寻找治疗新靶点提供理论依据。

角质形成细胞异常增殖凋亡是寻常型银屑病主要的病理改变，其具体分子机制尚不清楚。我们课题组前期大量的研究揭示了表观遗传学在银屑病发生发展中具有重要作用，m6A作为mRNA上含量最丰富的一种动态可逆的化学修饰，是当前表观遗传学研究热点，然而其在寻常型银屑病中的作用及机制鲜有研究。我们前期研究发现寻常型银屑病皮损中甲基转移酶复合物成份之一WTAP的表达显著增高，抑制WTAP的表达可降低HaCaT细胞中m6A水平，并促进细胞凋亡。本项目在此基础上，深入探讨了WTAP调控角质形成细胞异常增殖的分子机制，并进一步探索其在寻常型银屑病治疗中的应用前景。研究结果显示：WTAP可显著促进角质形成细胞分泌IL-1β，加速角质形成细胞细胞周期进程，促进角质形成细胞增殖；进一步机制研究证实WTAP可促进CDK2 mRNA的m6A甲基化，诱导CDK2表达升高，进而促进角质形成细胞周期进程及增殖。而体内干预WTAP表达可显著改善咪喹莫特诱导的小鼠银屑病样皮炎。通过以上体内外实验，我们首次揭示了WTAP通过诱导CDK2 mRNA m6A甲基化水平及表达升高，加速角质形成细胞周期，促进角质形成细胞增殖；证实了体内抑制WTAP的表达可显著改善小鼠银屑病样皮炎，为阐明银屑病发病机制提供了重要的理论和实验依据，为银屑病治疗提供新的靶点。