Proteomic profiling of the prefrontal cortex reveals Dysregulated Mitochondria-Metabolism-Synapse axis in a chronic Stress-Induced mouse model of depression.

Major depressive disorder (MDD) is a highly prevalent and disabling neuropsychiatric condition, its underlying molecular mechanisms remain incompletely understood. This study aimed to systematically characterize proteomic alterations in the prefrontal cortex associated with depression-like behaviors induced by chronic stress. Depression-like behaviors in mice were evaluated using standardized behavioral tests and confirmed by Digital Western blotting. Quantitative proteomic analysis of prefrontal cortex tissues was performed to compare chronic social defeat stress (CSDS) and control groups, identifying differentially expressed proteins (DEPs). These DEPs were subsequently subjected to bioinformatic analyses, including Gene Ontology (GO) enrichment and construction of protein-protein interaction (PPI) networks. Key DEPs were further validated by parallel reaction monitoring (PRM) and Western blotting. We found that CSDS mice displayed robust depression-like phenotypes, including decreased sucrose preference and increased immobility. Western blot analysis confirmed the dysregulation of ER stress markers, proinflammatory factors, and proteins related to synaptic plasticity. Proteomic analysis identified 95 differentially expressed proteins, with GO enrichment revealing predominant associations with gene regulation, mitochondrial, metabolic, and synaptic function. PPI network analysis highlighted hub proteins involved in mitochondrial, endoplasmic reticulum, and synaptic regulation. PRM and Western blot validation confirmed dysregulation in four functional modules: 1) Mitochondrial function (Mrpl17, Mrpl41)；2) Signal transduction (Rigi, Pbrm1, Plppr5, Glyr1)；3) Metabolic regulation(Pmvk, Rpl13a, Ubtd2, Tmem63b)；4) Synaptic plasticity (Kif21b, Klc4, Lama2, Col4a2). Our results demonstrate that chronic stress disrupts prefrontal cortical pathways that govern gene regulation, mitochondrial metabolism, and synaptic function, suggesting their concerted contribution to the pathophysiology of depression.