Impaired 26S proteasome causes learning and memory deficiency and induces neuroinflammation mediated by NF-κB in mice

A reduction in proteasome activity, loss of synapses, and increased neuroinflammation in the brain are hallmarks of aging and many neurodegenerative disorders, including Alzheimers disease (AD); however, whether proteasome dysfunction is causative to neuroinflammation remains less understood. In this study, we investigated the impact of 26S proteasome deficiency on neuroinflammation in the Psmc1 knockout (KO) mice deficient in a 19S proteasome subunit limited to the forebrain region. Our results revealed that impaired 26S proteasome causes reduced learning and memory capability and overt neuroinflammation in the Psmc1 KO brain at eight weeks of age. Pronounced neuroinflammation was confirmed by increased levels of several key immune response-related proteins, including Stat1, Trem2, and NF-{kappa}B, and by activation of astrocytes and microglia in the KO brain. To validate NF-{kappa}B mediating neuroinflammation, we administered a selective NF-{kappa}B inhibitor to the KO animals, and following the treatment, the KO mice exhibited improved learning and memory behaviors and reduced neuroinflammation compared to the control animals. These data indicate that impaired 26S proteasome causes AD-like cognitive deficiency and induces neuroinflammation mediated largely by NF-{kappa}B. These results may aid the development of effective therapeutics for AD and other neurodegenerative disorders where impaired proteasome activity is consistently coupled with neuroinflammation.