Synaptic NMDA Receptor Activation Induces Ubiquitination and Degradation of STEP.

NMDA receptor signaling is critical for the development of synaptic plasticity, learning, and memory, and dysregulation of NMDAR signaling is implicated in a number of neurological disorders including schizophrenia (SZ). Previous work has demonstrated that the STriatal-Enriched protein tyrosine Phosphatase 61 kDa (STEP) is elevated in human SZ postmortem cortical samples and after administration of psychotomimetics to cultures or mice. Here, we report that activation of synaptic NMDAR by bicuculline or D-serine results in the ubiquitination and proteasomal degradation of STEP, and increased surface localization of GluN1/GluN2B receptors. Moreover, bicuculline or D-serine treatments rescue the motor and cognitive deficits in MK-801-treated mice and reduce STEP in mouse frontal cortex. These results suggest that STEP may contribute to the therapeutic effects of D-serine.