Hippo/YAP和Wnt/β-catenin通路交叉对话促进幽门螺杆菌感染致胃黏膜损伤的机制研究

Helicobacter pylori (Hp) infection induces gastric mucosa via modulation of the multiple signaling pathways in hosts. Recent studies have shown a crosstalk occurs between the Hippo and Wnt signaling pathways, which is known to be involved in the regulation of cell growth and proliferation. YAP/TAZ and β-catenin are core components of Hippo and Wnt signaling, respectively. Our previous studies have shown that Hp infection resulted in aberrant activation of YAP/TAZ and downstream genes expression. Knockdown of TAZ significantly inhibited the levels of β-catenin and cell proliferation-associated genes, which suggests that the regulation of Wnt by Hippo pathway is involved in the pathogenesis of Hp infection. However, the role and mechanism of their crosstalk remain unknown. Therefore, this proposed project aims to investigate the role of the crosstalk between these pathways during Hp-induced gastric mucosa lesions in vitro and vivo by RNA interference, recombinant plasmids, and drug intervention, further examine YAP/TAZ interaction with β-catenin by immunoprecipitation, and finally explore the role of virulence factor CagA. The findings help to clarify the role of their crosstalk in Hp induced pathogenesis, which will provide the new rationale for eradication of Hp, especially CagA+Hp, and Hp infection-associated gastric diseases.

幽门螺杆菌（Hp）感染可通过干扰宿主信号通路诱导胃黏膜不同程度损伤，CagA是重要毒力因子。Hippo与Wnt信号存在多种形式的交叉对话，共同调控细胞增殖凋亡平衡，YAP/TAZ、β-catenin分别为两通路的核心分子。我们前期研究发现，Hp感染以依赖于CagA的方式激活YAP/TAZ及其下游靶基因。敲减TAZ后β-catenin及增殖相关基因表达下降，提示Hippo调控Wnt信号可能参与了Hp感染致病过程，然而两通路的相互调控关系仍不清楚。因此，本课题拟从体内、体外采用RNA干扰、重组质粒、药物干预等方法研究Hp感染致胃黏膜损伤过程中Hippo与Wnt信号的反馈调节机制；用免疫共沉淀技术观察YAP/TAZ与β-catenin蛋白相互作用；并探讨毒力因子CagA所扮演的角色，从而探明两通路对话在Hp致病中的作用，为Hp尤其是CagA+Hp根除及相关性疾病的治疗提供重要的理论依据。

幽门螺杆菌（Hp）感染可通过干扰宿主信号通路诱导胃黏膜不同程度损伤，CagA是重要毒力因子。Hippo与Wnt信号存在多种形式的交叉对话，共同调控细胞增殖凋亡平衡，YAP/TAZ、β-catenin分别为两通路的核心分子。本课题通过人体标本、细胞实验、动物实验采用细菌细胞共培养、免疫组化、免疫印迹、免疫共沉淀等方法研究Hippo/YAP和Wnt/β-catenin的交叉对话在Hp感染诱导胃黏膜损伤中的作用机制。我们的研究结果显示胃癌组织中YAP、β-catenin的表达显著高于癌旁正常组织，二者表达呈正相关。TAZ在胃癌组织中表达亦高于胃炎组织，且Hp阳性胃炎组织中TAZ表达高于Hp阴性胃炎组织。通过将Hp菌株与细胞共培养发现，Hp感染促进YAP/TAZ与β-catenin入核，增强其转录活性，此过程依赖于毒力因子CagA的表达。YAP和β-catenin协同促进Hp感染诱导的细胞过度增殖存活和恶性转化能力。进一步，敲减YAP或TAZ后可显著抑制Hp感染诱导的β-catenin入核。反过来，敲减β-catenin后又可抑制Hp感染诱导的TAZ入核。此外，Hp感染促进YAP/TAZ与β-catenin直接相互作用。最后，我们构建Hp感染小鼠疾病动物模型，采用YAP和β-catenin抑制剂处理，观察胃黏膜病理变化。结果显示YAP抑制剂Super-TDU和β-catenin抑制剂KYA1797K均可有效减轻Hp感染引起的小鼠胃部炎症和细胞增殖。综上，研究表明，Hp感染促进YAP/TAZ、β-catenin信号通路激活，促进二者的正反馈调节，从而诱导胃黏膜损伤病变。