OGT-mediated PIN O-GlcNAcylation drives depression-like behaviors by impairing NOS-stargazin-GluA1 signaling.

Major depressive disorder is associated with impaired excitatory synaptic transmission, but the molecular mechanisms linking chronic stress to altered AMPA receptor trafficking remain incompletely understood. Here we show that chronic mild stress increases OGT-mediated O-GlcNAcylation of PIN at serine 88, which stabilizes PIN and enhances its interaction with nitric oxide synthase. This suppresses nitric oxide synthase activity, reduces stargazin S-nitrosylation, weakens stargazin-GluA1 binding, and impairs GluA1-containing AMPA receptor trafficking. Genetic or pharmacological inhibition of OGT restores this signaling pathway and alleviates stress-induced depression-like behaviors in mice. These findings identify the OGT-PIN-NOS-stargazin axis as a regulator of stress-induced synaptic dysfunction and suggest that targeting OGT may help restore AMPA receptor trafficking in depression-related conditions.