Prx4参与的内质网应激反应对银屑病表皮角质形成细胞增殖分化的机制研究

Psoriasis is a chronic skin disease resulting from a complex interplay between the immune cells and genetic factors. The pathogenesis of psoriasis is characterized by hyperproliferation and aberrant differentiation of keratinocytes (KCs). Peroxiredoxin 4 (Prx4), a member of the peroxiredoxin family, is only locates in the Endoplasmic reticulum. The biochemical function of Prx4 in scavenging peroxide especially H2O2 has been well established. Interestingly, Prx4 also has an important role of maintaining ER homeostasis. Then, Prx4 is involved in cell proliferation and differentiation. Firstly, we will investigate the association with Prx4 and the proliferation and differentiation of KCs via overexpression and/or downregulation Prx4 in cell model. To understand the molecular basis of Prx4 mediated cell proliferation and differentiation, we will examine the global phosphokinase signaling change by human phosphor-kinase array. At same time, we will observe that Prx4 associates with the unfolded protein response (UPR) signaling pathways under induced-ER stress in human KCs. And we will determine how Prx4 and its interaction partner Grp78 affect ER homeostasis in human KCs proliferation and differentiation. We will construct the mice model of Imiquimod induced psoriasis in transgenic Prx4, to compare the psoriatic phenotypes with wild type mice. By the current research, Prx4 as a breakthrough point, elucidation of the relationship between ER stress signaling pathways and psoriasis may thus lead to novel research perspective for the pathogenesis of psoriasis.

寻常型银屑病是一定遗传背景下免疫细胞介导的慢性皮肤疾病，表皮角质形成细胞（KCs）高度增殖和异常分化是病理特点之一。作为过氧化物氧还蛋白家族中唯一定位分布于内质网的Prx4具有清除细胞H2O2维持内质网氧化还原微环境稳定的功能，这与细胞增殖分化密切相关。本研究将通过建立Prx4不同表达水平的表皮角质形成细胞模型，明确Prx4对KCs细胞增殖分化影响，利用磷酸化蛋白芯片方法确定Prx4参与增殖分化的信号通路；同时观察Prx4参与的内质网应激信号途径与KCs增殖分化平衡的关系，深入探讨Prx4和Grp78相互作用在其中的意义，解答Prx4参与的内质网应激反应影响KCs增殖分化过程的机制。借助Prx4转基因小鼠模型，在咪喹莫特诱导建立银屑病模型条件下，证实Prx4对银屑病发病机制及疾病进程的影响。研究以Prx4为切入点，试图阐述内质网应激反应在银屑病发病机制中的意义，为疾病机理研究提供新视角。

寻常型银屑病是一定遗传背景下免疫细胞介导的慢性皮肤疾病，表皮角质形成细胞（KCs）高度增殖和异常分化是病理特点之一。作为过氧化物氧还蛋白家族中唯一定位分布于内质网的Prx4具有清除细胞H2O2维持内质网氧化还原微环境稳定的功能，与细胞增殖分化密切相关。本研究通过建立Prx4不同表达水平的表皮角质形成细胞模型，证实了：1）表皮角质形成细胞在应激状态下，尤其是内质网应激（ER stress）、氧化应激等，高表达Prx4促进细胞增殖、抑制细胞分化；2）进而通过筛查内质网应激相关的多条信号通路，发现Prx4通过增加角质形成细胞活性氧(ROS)产生，活化IRE1α-XBP1信号，调控KCs分化能力；3）而Prx4产生这一生物学效应的分子机制是：KCs在内质网应激状态下，Prx4蛋白通过自身两个特异性半胱氨酸残基与内质网蛋白GRP78形成二硫键结合的分子复合物，从而释放GRP78对IRE1α-XBP1信号通路的抑制作用，产生抑制KCs分化的效应。同时我们发现寻常型银屑病皮损中Prx4表达较正常皮肤组织显著增高。因此本研究以Prx4作为切入点，在银屑病发病机制中率先引入内质网应激这一生物学表型，详细揭示了Prx4调控表皮角质形成细胞分化能力的分子机制，为完善寻常型银屑病发病机理的研究提供了新的实验数据。在本项目资助下，发表相关SCI论文7篇，其中JCR 1区论文2篇；协助培养硕士研究生3名，其中2名已毕业；直接参与本项目的博士研究生2名。