Epithelial disruption is the initiation of most infectious disease. Regulation of epithelium apoptosis may play a key role in balance the survival competition between resident bacteria and host cells. The role of the mTOR/p70S6K pathway in preventing apoptosis of human gingival epithelial cells (hGECs) infected with Porphyromonas gingivalis (Pg) was investigated in order to further understand the survival strategy of the epithelial cells in during Pg infecting. hGECs was challenged with Pg for 4, 12, and 24 h. Additionally, hGECs was pretreated with LY294002 (PI3K signaling inhibitor) or Compound C (AMPK inhibitor) for 12 h and exposed them to Pg for 24 h. Subsequently, apoptosis was detected using flow cytometry, and expression and activity of Bcl-2, Bad, Bax, PI3K, AKT, AMPK, mTOR, and p70S6K proteins were analyzed using western blotting. Pg-infecting did not increase apoptosis of hGECs; but the expression ratio of Bad to Bcl-2 was increased after infecting. In contrast, Bad(Ser136) phosphorylation was promoted, accompanied by a significant reduction of mTOR/p70S6K and PI3K/AKT signaling, along with the upregulation of AMPK(Thr172) signaling. Morrover, the PI3K inhibitor LY294002 promoted Pg-mediated reduction of mTOR/p70S6K expression, and the increase of AMPK signaling and Bad(Ser136) phosphorylation rate, eventually decreasing apoptosis. While Compound C inhibited Pg-mediated activation of AMPK and downregulation of mTOR/p70S6K signaling, significantly reduced the Bad(Ser136) phosphorylation rate, thereby increasing apoptosis. Thus, hGECs prevent apoptosis via an inherent cellular-homeostasis, pro-survival mechanism during Pg infection, the AMPK/mTOR/p70S6K pathway helps prevent apoptosis in hGECs infected with Pg by regulating Bad(Ser136) phosphorylation.
基金:
Joint Special Funds for
the Department of Science and Technology of Yunnan ProvinceKunming Medical University (Grant numbers 2019FE001(-168)
and 2017FE468(-082)); Kunming Medical University PhD Student
Innovation Fund (Grant number 2022B21); National Nature Science
Foundation of China (Grant number 81860487); and high-level
health technology talent project in Yunnan Province (Grant number
D2018031).