4R Tau Modulates Cocaine-Associated Memory through Adult Dorsal Hippocampal Neurogenesis

The development, persistence and relapse of drug addiction require drug memory that generally develops with drug administration-paired contextual stimuli. Adult hippocampal neurogenesis (AHN) contributes to cocaine memory formation; however, the underlying mechanism remains unclear. Male mice hippocampal expression of Tau was significantly decreased during the cocaine-associated memory formation. Genetic overexpression of four microtubule-binding repeats Tau (4R Tau) in the mice hippocampus disrupted cocaine memory by suppressing AHN. Furthermore, 4R Tau directly interacted with phosphoinositide 3-kinase (PI3K)-p85 and impaired its nuclear translocation and PI3K-AKT signaling, processes required for hippocampal neuron proliferation. Collectively, 4R Tau modulates cocaine memory formation by disrupting AHN, suggesting a novel mechanism underlying cocaine memory formation and provide a new strategy for the treatment of cocaine addiction.SIGNIFICANCE STATEMENT Drug memory that generally develops with drug-paired contextual stimuli and drug administration is critical for the development, persistence and relapse of drug addiction. Previous studies have suggested that adult hippocampal neurogenesis (AHN) plays a role in cocaine memory formation. Here, we showed that Tau was significantly downregulated in the hippocampus in the cocaine memory formation. Tau knock-out (KO) promoted AHN in the hippocampal dentate gyrus (DG), resulting in the enhanced memory formation evoked by cocaine-cue stimuli. In contrast, genetically overexpressed 4R Tau in the hippocampus disrupted cocaine-cue memory by suppressing AHN. In addition, 4R Tau interacted directly with phosphoinositide 3-kinase (PI3K)-p85 and hindered its nuclear translocation, eventually repressing PI3K-AKT signaling, which is essential for hippocampal neuronal proliferation.