Intermittent hypoxia reduces microglia proliferation and induces DNA damage in vitro

Objective(s):Intermittent hypoxia (IH), caused by obstructive sleep apnea (OSA), could cause hippocampus or neuron damage through multiple signaling pathways, while the underlying mechanisms are still unclear. Thus, the present study aimed to explore the effect of IH on the biological functions of microglia cells. Materials and Methods:Cell proliferation of BV۲ cells after exposure to IH were observed by MTT assay and then DNA damage was detected by comet assay. RNA-sequencing assay was performed in cells under IH condition and normal conditions to find out the differentially expressed genes, which were further confirmed by reverse transcriptase polymerase chain reaction (RT-PCR) and Western blot assay. Results:As results, IH inhibited the proliferation of BV۲ cells, as well as caused DNA damage. RNA-sequencing assay revealed ۴ differentially expressed genes (p۲۱, Cyclin D۱, Cyclin E۲, and Gadd۴۵α) which were associated with the network of P۵۳ signaling pathways in BV۲ cells, among which, p۲۱ and Gadd۴۵α were dramatically increased while Cyclin D۱ and Cyclin E۲ were both decreased significantly. Moreover, inflammatory factors including IL-۶, TNF-α and iNOS were significantly up-regulated in microglia cells under IH conditions for ۸ hr. Conclusion:Our results indicated that IH could inhibit cyclin D۱ and cyclin E۲ expression via initiating multiple P۵۳ pathways, which further blocked cell cycle transition and attenuated proliferative capability of BV۲ cells. Meanwhile, IH activated inflammation reactions in BV۲ cells. Present study elaborate the effects of IH on biological functions of microglia and provide theoretical foundation for further study on new therapy methods for OSA.

Keywords:

Inflammatory cytokine , Intermittent hypoxia , Microglia , P۵۳ signaling pathways