Boosting Proteasome Activity: A Novel Mechanism of NMDAR Blockers Against Neurodegeneration

NMDAR antagonists, such as memantine and ketamine, have shown efficacy in treating neurodegenerative diseases and major depression. The mechanism by which these drugs correct the aforementioned diseases is still unknown. Our study reveals that these antagonists significantly enhance 20S proteasome activity, crucial for degrading intrinsically disordered, oxidatively damaged, or misfolded proteins, factors pivotal in neurodegenerative diseases like Alzheimers and Parkinsons. In a mouse model, ketamine administration notably altered brain synaptic protein profiles within two hours, downregulating proteins linked to neurodegenerative conditions. Furthermore, the altered proteins exhibited enrichment in terms related to plasticity and potentiation, including retrograde endocannabinoid signaling--a pivotal pathway in both short- and long-term plasticity that may elucidate the long-lasting effects of ketamine in major depression. Via the ubiquitin-independent 20S proteasome pathway (UIPS), these drugs maintain cellular protein homeostasis, crucial as proteasome activity declines with age leading to protein aggregation and disease symptoms. The elucidation of the mechanistic pathways underlying the therapeutic effects of NMDAR antagonists holds promise for developing new treatment strategies for brain diseases, including schizophrenia, Alzheimers, and Parkinsons.