Nogo-A Drives Alzheimer's Disease Progression by Inducing Tauopathy Vulnerability

Tauopathies, a group of neurodegenerative disorders, are characterized by disrupted homeostasis of the microtubule binding protein tau. Nogo-A mainly hinders axonal growth and development in neurons, but the underlying mechanism of tau vulnerability has not been determined. Here, to gain more comprehensive insights into the impact of Nogo-A on tau protein expression, we showed that Nogo-A induces tau hyperphosphorylation, synapse loss and cognitive dysfunction. Consistent with the biological function of tau hyperphosphorylation, Nogo-A-induced tau hyperphosphorylation altered microtubule stability, which causes synaptic dysfunction. Mechanistically, Nogo-A-induced tau hyperphosphorylation was abolished by the Nogo-A antagonist NEP1-40 in primary neurons. Surprisingly, downregulation of Nogo-A in the hippocampus of AD mice (hTau. P301S) inhibited tau hyperphosphorylation at the AT8, Thr181, The231 and Ser404 sites and rescued synaptic loss and cognitive impairment in AD mice. Our findings exhibit a strong degree of consistency with Nogo-A-induced tauopathy vulnerability, reinforcing the coherence and reliability of our research. Furthermore, in mice, Nogo-A increases tauopathy vulnerability to exacerbate AD progression via ROCK/AKT/GSK3β signaling. Together, our findings provide new insight into the function of Nogo-A in regulating tau hyperphosphorylation and reveal an effective treatment strategy for tauopathies.