Autophagy promotes membrane trafficking of NR2B to alleviate depression by inhibiting AQP4 expression in mice

Abstract

Depression is a high-incidence mental illness that seriously affects human health. AQP4 has been reported to be closely associated with depression, while the underlying mechanism is still unclear. This work aimed to investigate the functional role of AQP4 in depression. Depression mouse model was constructed by administration of chronic social defeat stress (CSDS). We found that AQP4 was highly expressed in the hippocampal tissues of CSDS mice. AQP4 knockdown alleviated depression and enhanced the expression of NR2B and PSD95 in CSDS mice. Moreover, primary hippocampal neurons were treated with N-methyl-d-aspartate (NMDA) to induce neuron injury. AQP4 overexpression repressed cell viability and promoted apoptosis of NMDA-treated primary hippocampal neurons. AQP4 up-regulation repressed the expression of NR2B (surface), and enhanced the expression of NR2B (intracellular), P-NR2B, CaMK II and CK2 in the NMDA-treated primary hippocampal neurons. The influence conferred by AQP4 up-regulation was abolished by KN-93 (CaMK II inhibitor) or TBB (CK2 inhibitor) treatment. Rapamycin treatment enhanced the expression of NR2B (surface), and repressed the expression of AQP4, NR2B (intracellular) and P-NR2B in the primary hippocampal neurons by activating autophagy. The activated autophagy alleviated depression in CSDS mice by repressing AQP4 expression. In conclusion, our data demonstrated that autophagy ameliorated depression by repressing AQP4 expression in mice, and AQP4 knockdown promoted membrane trafficking of NR2B and inhibited phosphorylation of NR2B via CaMK II/CK2 pathway. Thus, our work suggests that AQP4 may be a promising molecular target for the development of antidepressant drugs.

Keywords: AQP4; Autophagy; CK2; CaMK II; Depression; NR2B.