Tp47 induces cell death involving autophagy and mTOR in human microglial HMO6 cells

Abstract

Background: Tp47 can induce immune cells to produce numerous inflammatory factors, some of which can trigger autophagy. Increased autophagy has a dual effect on cell survival. However, whether Tp47 induces autophagy in microglia is unknown.

Objective: To evaluate the potential role of Tp47 in microglia.

Methods: After treatment with Tp47, autophagy-related proteins were assessed in HMO6 human microglial cells by flow cytometry, Western blotting and immunofluorescence. Cell death was assessed by flow cytometry and trypan blue staining. Changes in mTOR pathway proteins were explored by using Western blotting.

Results: After treatment with Tp47, a gradual increase in total LC3 expression was observed as a dose- and time-dependent accumulation of its active form, LC3-II (P < 0.05), but P62 expression was downregulated (P < 0.05). Moreover, microglial mortality gradually increased in a dose- and time-dependent manner. 3-Methyladenine (3-MA), a specific inhibitor of PI3KC3, reversed autophagy and cell death. The mortality rate of HMO6 microglial cells treated with Tp47 was approximately 13.7 ± 2%, and the basal expression of p-mTOR, p-p70s6k and p-S6 in these cells was significantly downregulated by Tp47. Moreover, the mortality rate of microglia was significantly reduced after mTOR agonist intervention.

Conclusion: In human microglial HMO6 cells, Tp47 induces autophagy- and mTOR pathway-dependent cell death.

Keywords: Autophagy; Microglia; Tp47.