MALAT1 Regulated mTOR-Mediated Tau Hyperphosphorylation by Acting as a ceRNA of miR144 in Hippocampus Cells Exposed to High Glucose

AIM: High glucose (HG)-induced activation of mTOR promotes tau phosphorylation and leads to diabetes-associated dementia. This study aimed to explore the role of metastasis associated in lung adenocarcinoma transcript 1 (MALAT1) in HG-induced neuronal cell injury. METHODS: Hippocampus cells were isolated from C57BL/6J mice. After 6 days of culture, the cells were incubated with 5.5 mM glucose in normal medium or 75 mM glucose for 4 days. Cells were transfected with miR-144 mimic, miR-144 inhibitor, siRNA for MALAT1 or corresponding controls. Gene expression was detected by PCR and Western blot analysis. RESULTS: HG increased the levels of MALAT1 and p-tau in hippocampal cells. Knockdown of MALAT1 partially reversed the effects of HG on mTOR activity and p-tau protein levels. MALAT1 functioned as competing endogenous RNA (ceRNA) for miR-144, and pre-treatment with MALAT1 siRNA decreased mTOR activity and p-tau protein level in HG-treated hippocampal cells, which was significantly attenuated by miR-144 mimics. Moreover, miR-144 negatively regulated the expression of mTOR and knockdown of MALAT1 suppressed mTOR, while overexpression of mTOR abrogated protective effects of MALAT1 knockdown in HG-treated hippocampal cells. CONCLUSION: MALAT1 knockdown prevented HG-induced mTOR activation and inhibited tau phosphorylation. MALAT1 may be a therapy target for diabetes associated dementia.