Pyk2 Tyrosine Kinase Facilitates Porphyromonas gingivalis Internalization and Autophagy in Immortalized Human Gingival Epithelial Cells

Abstract Background: Porphyromonas gingivalis (P. gingivalis), the keystone bacterial pathogen of chronic periodontitis, were able to invade immortalized human gingival epithelial cells (HGECs) and elicit a series of inflammatory responses. Proline-rich tyrosine kinase2 (Pyk2), a member of the focal adhesion kinase (FAK) family as non-receptor tyrosine kinase was universally acknowledged to be closely related to cell adhesion, migration and proliferation. Methods and methods: Epi-4 cells were infected by P. gingivalis ATCC 33277 (MOI = 100). P. gingivalis internalization and cellular autophagy were evaluated by transmission electron and scanning electron microscopy. Light chain (LC) 3 Ⅱ and Pyk2 protein expression was assessed in the epi-4 cells by immunocytochemistry and immunofluorescence. LC3 Ⅱ and Pyk2 mRNA and protein expression in P. gingivalis-infected epi4 cells were measured in the absence or presence of Pyk2 inhibitor (TAE226) using real-time PCR and western blotting. The number of intracellular P. gingivalis was determined by the antibiotic protection assay. Results: Our results demonstrated that P. gingivalis internalization induced autophagosomes in epi-4 cells. The enhanced levels of autophagy and Pyk2 expression by P. gingivalis were time-dependent. Furthermore, Pyk2 could regulate P. gingivalis internalization and autophagy. Pretreatment with TAE226 prevented these infection-induced changes in epi-4 cells. Conclusion:Pyk2 tyrosine kinase could facilitate P. gingivalis internalization and autophagy in epi-4 cells. This study further elucidated the mechanism of P. gingivalis pathogenesis and provided new perspectives and targets for treating and preventing periodontitis.