Microglial Sestrin2 alleviates depressive-like behaviors and cognitive impairment in a YTHDF1-dependent manner

ObjectiveThis study aims to investigate the role of microglial Sestrin2 in chronic unpredictable stress (CUS)-induced depressive-like behaviors and cognitive impairment in mice, and to explore the upstream molecular mechanism underlying the abnormal expression of microglial Sestrin2.MethodsMicroglia-specific overexpression of Sestrin2 was achieved by injecting adeno-associated virus (AAV) into the CUS mouse hippocampus. Depressive-like behaviors were assessed using sucrose preference, tail suspension, and forced swim tests. Cognitive function was evaluated by the Morris water maze. Levels of IL-1β and IL-6 in the hippocampus and cell supernatants were measured by ELISA. BV2 microglial cells were used for in vitro mechanistic studies. YTHDF1 siRNA and overexpressive lentivirus were used to regulate YTHDF1 expression in vitro. RNA immunoprecipitation was performed to demonstrate the physical interaction between YTHDF1 and Sestrin2 mRNA.ResultsSestrin2 expression was significantly reduced in the hippocampus of CUS mice. Overexpression of Sestrin2 specifically in microglia ameliorated CUS-induced depressive-like behaviors, cognitive impairment, and inflammatory levels. YTHDF1 expression was also reduced in the CUS hippocampus. Mechanistically, YTHDF1 bound to Sestrin2 mRNA and knockdown of YTHDF1 decreased Sestrin2 expression. Molecular biology prediction results showed that positions 1943 and 2,114 of Sestrin2 mRNA are high-confidence N6-methyladenosine (m6A) modification sites. Mutation of the 2,114 site on Sestrin2 mRNA inhibited the effect of YTHDF1 on 3Flag expression. Furthermore, YTHDF1 knockdown promoted IL-1β and IL-6 production in BV2 cells, which was reversed by Sestrin2 overexpression.ConclusionMicroglial Sestrin2 alleviates depressive-like behaviors, cognitive impairment and neuroinflammation. YTHDF1 regulates Sestrin2 expression via an m6A-dependent mechanism, and the YTHDF1-Sestrin2 axis may represent a novel therapeutic target for major depressive disorder.