Project Summary Mixed neuropathologies are the most common cause of the clinical syndrome of dementia, including Alzheimer’s disease (AD) dementia, and are also common among persons with mild cognitive impairment, the prodromal stage of AD. Exploiting novel constitutive and conditional knockout lines as well as transgenic mouse lines, we now propose bidirectional genetic effort designed to uncover key knowledge gaps linking alpha-synuclein (αSyn) and tau coupling, and their relationships to synaptic and cognitive function. Leveraging emerging evidence from independent groups including our own, we will test the central hypothesis that αSyn modulates tau pathology and tau-associated cognitive and synaptic deficits. In the light of novel findings reported in the preliminary results, we will i) test the prediction that constitutive ablation of the SNCA gene encoding αSyn alleviates tau pathology and tau-induced cognitive deficits in a model of tauopathy and ii) test the hypothesis that overexpression of human wild-type αSyn exacerbates tau pathology and tau-induced cognitive deficits in a model of tauopathy, thereby providing a preclinical proof-of-principle that targeting this αSyn/tau coupling might be therapeutically beneficial.

Project Narrative A central question in Alzheimer’s disease (AD) is how synapse loss occurs and whether (and if so, how) synaptic and memory loss can be attenuated or halted. This effort seeks to uncover the role of αSyn on tau aggregation, tau deposition and tau-mediated cognitive impairment. We will be a bidirectional genetic approach to assess whether constitutive ablation of the SNCA gene encoding αSyn alleviates tau pathology and tau-induced cognitive deficits in a model of tauopathy, whether AβO directly perturb the physiology of excitatory and inhibitory neurons differentially and whether (and if so, how) site-specific tau phosphorylation regulates synaptic biology, neuronal and cognitive function.