Pyk2调控牙龈卟啉单胞菌内化及牙龈上皮细胞自噬的分子机制研究

P. gingivalis, which is the main pathogen of chronic periodontitis, can be internalized in and chronically persist in gingival epithelial cells, and its mechanism is still not clear. Previous research has shown that FAK as an important signal molecule mediating P. gingivalis internalization was degraded by gingipains. So we assumed that some other signaling pathways might regulate P. gingivalis internalization. In our preliminary work we found that P. gingivalis internalization promoted Pyk2 and some other signal molecules expression and increased the expression of autophagy-related gene. So we hypothesized that Pyk2 may activate β-catenin and promote P. gingivalis internalization by inducing the rearrangement of cytoskeleton. β-catenin may activate the FOXO and promote the autophagy of the gingival epithelial cells. We plan to study the effect of Pyk2 on P.gingivalis internalization by siRNA and to explore the role of Pyk2-β -catenin-FOXO pathway on autophagy, which helps to elucidate the pathogenic mechanism of intracellular persistence of P. gingivalis by internalization and autophagy induced by P. gingivalis, to establish an intercellular signaling network between P. gingivalis and gingival epithelial cells and to provide new targets for the treatment and prevention of periodontitis.

P.gingivalis是慢性牙周炎的主要致病菌，该菌可内化并在牙龈上皮细胞内长期存留，其机制尚不明晰。以往研究显示，FAK作为介导P.gingivalis内化重要的信号分子被牙龈素所降解，故提出可能存在其他信号通路调控内化。前期工作中我们发现P. gingivalis内化使Pyk2等信号分子表达增高，自噬相关基因表达增加。由此提出假说，Pyk2可能通过活化β-catenin引起细胞骨架重排而促进P.gingivalis内化，β-catenin又可激活FOXO而启动牙龈上皮细胞自噬。我们拟利用RNA干涉研究Pyk2对P.gingivalis内化的影响，并探讨Pyk2-β-catenin-FOXO通路对细胞自噬的作用，有助于阐明P.gingivalis通过内化及其诱导的细胞自噬得以胞内存活的致病机理，建立P.gingivalis和牙龈上皮细胞间信号传递网络，为治疗和预防牙周炎提供新的靶点。

P.gingivalis作为慢性牙周炎的主要致病菌，能够侵入牙龈上皮细胞，实现病原菌内化；并且进一步激发复杂细胞生命过程，从而实现病原菌在胞内的长期存留。研究工作中我们发现P. gingivalis内化牙龈上皮细胞过程中Pyk2信号分子表达增高，并随感染时间呈正相关；与此同时，自噬相关基因LC3Ⅱ和P62的表达变化提示自噬活动增强。为阐明P. gingivalis内化及激发细胞自噬的致病机制，我们利用Pyk2特异性抑制剂TAE226研究Pyk2抑制对P.gingivalis内化的影响，同时探讨Pyk2抑制对细胞自噬的作用。研究发现Pyk2抑制显著减弱P.gingivalis内化并下调LC3Ⅱ表达，从而证明Pyk2正是通过调节细胞自噬过程影响P. gingivalis内化。通过人基因表达谱芯片筛选Pyk2调控的下游靶基因及参与的信号转导通路，建立P. gingivalis和牙龈上皮细胞间信号传递的网络系统，寻找新的信号传导通路和调节位点。结果阐明P.gingivalis内化牙龈上皮细胞过程通过活化Pyk2信号分子并激发细胞自噬从而实现胞内存活的致病过程，为治疗和预防牙周炎提供新的思路。