蛋白酶激活受体1 (PAR1)是凝血酶, 金属蛋白酶MMP1等蛋白酶的受体，与炎症及肿瘤的发生和转移密切相关。抑素蛋白（prohibitins， PHBs）高度保守。我们目前创新结果是: 阐明PAR1是两栖类三叶因子Bm-TFF2作用的膜受体。以Bm-TFF2为分子探针，首次发现PHBs与PAR1的联系及对PAR1受体激活的调节作用，初步揭示PHB1参与了PAR1的蛋白降解过程。本项目旨在：以正常原代培养的细胞和异常的肿瘤细胞为模型研究未知的PHB1调控 PAR1内化转运及降解的功能和生物学意义；揭示PHB1调节 PAR1转运及降解的作用机制，包括PHB1与PAR1的相互作用，PHB1各个功能结构域的贡献和作用；利用细胞和动物模型揭示PHB1调控 PAR1内化转运及降解对肿瘤细胞生长与转移的影响。促进深入解析蛋白酶激活的PAR1受体信号与PHBs蛋白的关系及在人类复杂疾病中的分子病理意义。

Protease-activated receptor-1 (PAR1) is the receptor of proteases such as thrombin and matrix metalloprotease 1 (MMP1) and is closely linked to inflammation, tumorigenesis and metastasis. Prohibitins (PHBs), being members of stomatin/prohibitin/flotillin/ HflK/C superfamily, are ubiquitously expressed and highly evolutionarily conserved proteins. There are two members of PHBs in mammals, namely PHB1 (32 kDa) and PHB2 (37 kDa). The absence of PHBs leads to severe phenotypes and deficiencies in higher eukaryotes, and PHB knockout is lethal in mice. Our recent innovative results show that PAR1 is the membrane receptor of amphibian trefoil factor (Bm-TFF2), a mucosal healing factor, and mediates its biological functions. Based on the clues, we further showed that protease-activated receptor 4 is able to mediate the mucosal healing function of human trefoil factor 2 (hTFF2) (Zhang Y et al., Cell Mol Life Sci 2011, 68, 3771-3780). Interestingly, along this line, our results revealed that down-regulation of PAR4 expression occurs frequently in human gastric cancers and exhibits association with more aggressive gastric cancer, suggesting the importance of putative TFF2-PAR4 signaling in mucosal healing (Zhang Y et al., Int J Biochem Cell Biol 2011, 43, 1277-1283). Surprisingly, using Bm-TFF2 as a molecular probe, for the first time, we found that PHBs are required in protease-activated receptor 1-mediated human platelet aggregation, which is different from mouse platelets. They were found to interact and co-localize with PAR1 in human platelet membrane and regulate PAR1-mediated platelet activation (Zhang Y et al., J Thromb. Haemosta 2012, 10，411-418). Our preliminary results on cultured cells further revealed that PHB1 is involved in the process of PAR1 internalization and degradation. Present project will focuses on: (1) exploring the unknown functions and biological significance of PHB1 in regulating PAR1 internalization, trafficking and degradation by using normal primary cultured cells and abnormal tumor cells; (2) clarifying the regulatory mechanisms of PHB1 in PAR1 trafficking and degradation, including the interaction between PHB1 and PAR1 and the contribution of each of PHB1 functional domains; (3) investigating the biological influence of PHB1 regulating PAR1 internalization, trafficking and degradation on the ability of oncogensis and metastasis of tumor cells in vitro and in vivo. The project could promote the understanding of the relationship between protease-activated PAR1 signaling pathway and PHBs, and the related molecular pathological significance in complex human diseases.