Abstract
Protein interactions of Tau are of interest in efforts to decipher pathogenesis in Alzheimer's disease, a subset of frontotemporal dementias, and other tauopathies. We CRISPR-Cas9 edited two human cell lines to generate broadly adaptable models for neurodegeneration research. We applied the system to inducibly express balanced levels of 3-repeat and 4-repeat wild-type or P301L mutant Tau. Following 12-h induction, quantitative mass spectrometry revealed the Parkinson's disease-causing protein DJ-1 and non-muscle myosins as Tau interactors whose binding to Tau was profoundly influenced by the presence or absence of the P301L mutation. The presence of wild-type Tau stabilized non-muscle myosins at higher steady-state levels. Strikingly, in human differentiated co-cultures of neuronal and glial cells, the preferential interaction of non-muscle myosins to wild-type Tau depended on myosin ATPase activity. Consistently, transgenic P301L Tau mice exhibited reduced phosphorylation of regulatory myosin light chains known to activate this ATPase. The direct link of Tau to non-muscle myosins corroborates independently proposed roles of Tau in maintaining dendritic spines and mitochondrial fission biology, two subcellular niches affected early in tauopathies.