Sufu在银屑病发生发展中的作用机制研究

Psoriasis is a common and clinically heterogeneous group of immune-mediated chronic proliferative skin diseases. Although aberrant activation of an individual pathway may play important roles in the pathogensis of psoriais, these pathways rarely operate in isolation. Crosstalk between signaling pathways has the potential to profoundly add to the complexity of cellular responses to external stimuli. Suppressor of fused (Sufu) is a powerful negative regulator of hedgehog, WNT and other signaling pathways. Sufu plays a central role in the Hh pathway by influencing the balance between GliA and GliR; Sufu functions as a negative regulator of Wnt/β-cantenin signaling by binding to β-catenin of Wnt pathway and exports from the nucleus; TNFα treatment and mTOR signal S6K1 ectopic expression blocked the interaction between Sufu and Gli1; The ectopic expression/depletion of human ΔNp63α resulted in an increase/decrease of Sufu. Therefore, Sufu provides a link between the Hh, Wnt, mTOR and p63 signals. Sufu regulates these signaling pathways and prevent cell proliferation. Up to now, no documented records were found about sufu and psoriasis by searching pubmed. Therefore, it is worthwhile to investigate the role of Sufu in the differentiation of keratinocytes by using psoriasis as a model. Furthermore, how Sufu links the Hh, Wnt, mTOR and p63 signaling pathways in psoriasis should be clarified. What is the mechanism of downstream gene regulation by Sufu and how are psoriatic keratinocyte type-specific responses determined? Whether Sufu transgenic and knockout mice could inhibit or induce psoriatic phenotype in mouse skin should also be identified. Addressing these issues and identification of specific crosstalk networks in psoriatic keratinocytes are crucial for understanding these fascinating signalling pathways and for developing therapeutic strategies to target the medical consequences of its dysregulation in psoriasis.

银屑病是免疫介导的增殖性皮肤病，信号通路在其发生发展中发挥重要作用。Sufu是Hh和Wnt信号通路的负性调控因子，在Hh通路中平衡GliA和GliR发挥中心作用；结合β-catenin并将之转出核外负性调控Wnt信号通路；TNFα作用于mTOR信号通路阻断Sufu与Gli1的相互作用；ΔNp63α的异常表达/缺失导致Sufu 的增加/降低。因此，Sufu可能将Hh、Wnt、mTOR和p63信号分子联系起来，调节这些信号通路。目前尚未检索到Sufu与银屑病的相关研究文献。我们以银屑病作为模型，探讨Sufu如何将Hh、Wnt、mTOR、GC和p63联系起来；Sufu是否是这些信号通路的交叉点？Sufu是如何调节下游靶分子的？Sufu表达异常是否影响角质形成细胞的功能？Sufu转基因或基因敲除能否抑制/诱发银屑病？阐明这些问题，将对进一步明确银屑病的发病机制、发现新的治疗靶标，都具有重要的意义。

Sufu（Suppressor of fused）是脊椎动物Hedgehog信号通路的抑制分子，也是Wnt/β-catenin等信号通路的负调控因子，它具有多种复杂的功能，不仅是正常组织发育的调节者，也能阻止恶性肿瘤的发生。因此，Sufu可能对皮肤发育发挥着重要作用。我们的研究构建并验证过表达hSufu的转基因小鼠。通过PCR、Western blot和免疫荧光染色进一步验证。结果发现：K14-hSufu TG小鼠表征差异：与野生型（WT）小鼠相比较，7日龄和7周龄TG小鼠的背部皮肤的真皮层显著减少，而皮下脂肪组织却显著增加。hSufu TG小鼠皮肤伤口愈合延迟。Sufu过表达抑制表皮角质形成细胞的迁移和增殖。表皮过表达Sufu影响真皮。Sufu通过抑制Hh / Gli和Wnt /β-catenin信号通路来延缓伤口愈合。Sufu在皮肤发育过程中调节表皮角质形成细胞和真皮成纤维细胞的细胞特性，并通过抑制Hh / Gli和Wnt /β-catenin信号通路来延迟伤口愈合。Sufu在BLM诱导的小鼠真皮成纤维细胞中表达下调。hSufu转基因小鼠抵抗BLM诱导的皮肤纤维化。BLM诱导后，Sufu与真皮成纤维细胞活化和胶原合成相关联。我们进行了体外实验，观察BLM诱导后，WT小鼠和TG小鼠的真皮成纤维细胞的活化和胶原合成。在成纤维细胞中，BLM刺激诱导的fibronectin 和collagen I蛋白的表达水平来看，TG小鼠的表达相对更少。总体而言， TG小鼠成纤维细胞对BLM的反应性比WT小鼠的小。Sufu可能通过下调Wnt/ β-catenin通路的活化，来抑制BLM诱导的皮肤纤维化。我们的研究发现Sufu有效的抑制了体内β-catenin 的活化，这可能有助于在小鼠硬皮病模型中抑制皮肤纤维化的发生。TG小鼠β-catenin的基因和蛋白水平均显著下调。这表明Sufu过表达可能增加了β-catenin的降解。结论：我们的研究发现了sufu可能通过下调Wnt/ β-catenin通路的活化来抑制皮肤纤维化。本研究拓展了sufu在纤维化疾病中的认识，可能为今后皮肤纤维化过程的研究和治疗提供新的思路。