MicroRNA-132 attenuates LPS-induced inflammatory injury by targeting TRAF6 in neuronal cell line HT-22.

Abstract

Epilepsy is a common neurological disorder in the central nervous system. Inflammation disrupts the blood-brain barrier (BBB), which is responsible for maintaining brain homeostasis. This study was aimed to investigate the functional role of microRNA (miR)-132 in hippocampal HT-22 cells under lipopolysaccharide (LPS) stimulation. In vitro cell inflammatory model was constructed by LPS stimulation. Inflammatory cell injury was evaluated according to the alterations of cell viability, apoptosis, and expression of inflammatory cytokines. Then, miR-132 level after LPS treatment was assessed. Subsequently, miR-132 was abnormally expressed after cell transfection, and the effects of miR-132 on LPS-induced cell inflammatory injury as well as phosphorylated levels of key kinases in the NF-κB and MAPK kinase (MEK)/ERK pathways were determined. The target gene of miR-132 was virtually screened and verified, and whether miR-132 affected HT-22 cells under LPS stimulation through regulating the target gene was verified. The results showed that the level of miR-132 was down-regulated by LPS in HT-22 cells, and the LPS-induced inflammatory injury could be reduced by miR-132 overexpression. Then, the phosphorylated levels of kinases in the NF-κB and MEK/ERK pathways were decreased by miR-132 overexpression. Tumor necrosis factor receptor-associated factor 6 (TRAF6) was predicted and verified to be a target of miR-132. Moreover, the alterations induced by miR-132 overexpression in the LPS-treated HT-22 cells were abrogated by TRAF6 overexpression. Therefore, we drew the conclusion that LPS down-regulated miR-132 and miR-132 attenuated LPS-induced inflammatory cell injury by targeting TRAF6, along with the inhibition of the NF-κB and MEK/ERK pathways.