Xiaoyaosan and isoliquiritigenin remodel depression-associated chromatin 3D structure and phase separation of NF-κB p65.

Abstract

Xiaoyaosan (XYS) is a classical traditional prescription with well-documented antidepressant effects. However, the active components and molecular mechanisms to alleviate depression remain unclear. In this study, using chronic social defeat stress (CSDS) and lipopolysaccharide (LPS)-induced depression models, we found that XYS and its key ingredient isoliquiritigenin (ILG) not only significantly improved depressive-like behaviors in mice but also exerted dual regulatory effects at the cellular level, promoting hippocampal neural stem cell proliferation and differentiation, while inhibiting microglia-mediated neuroinflammation. Using Hi-C technology, we discovered that XYS and ILG reversed the abnormal chromatin 3D structure in hippocampal microglia of depression models. Integrated analyses of transcriptomics, molecular docking, and 3D genomics identified the transcription factor p65 as a target of XYS and ILG. Co-culture experiments with microglia and neural stem cells further confirmed that overexpression of p65 promotes inflammation and inhibits neuronal growth. In depressed mice, NF-κB p65 expression was elevated and further formed phase separated condensates, which was effectively suppressed by XYS and ILG. This study reveals how XYS and its active component ILG function mechanistically to exert therapeutic effects on depression, including restoring chromatin 3D structure, and normalizing pathological phase separation of NF-κB p65, and reversing depressive phenotypes. Collectively, these findings provide a solid experimental foundation for the development of natural antidepressants.