Tauopathies: Calmodulin Regulates Tau Hyperphosphorylation and Its Transformation into Disease-Specific Aggregates

Tauopathies are a diverse group of neurodegenerative diseases characterized by the presence of Tau inclusions in neurons and glia. Rather than the classic steps in the transformation of Tau into neurofibrillary tangles, as first studied in Alzheimer's disease, studies on tauopathies reveal the presence of diverse Tau aggregates that appear to be disease-specific. Regardless, the phosphorylation and hyperphosphorylation of Tau, involving various kinases and phosphatases, appear to be central to all tauopathies. As in other neurodegenerative diseases, calcium dysregulation is an early event in multiple tauopathies, where it activates calmodulin to effect downstream events. Here, the events of Tau phosphorylation and hyperphosphorylation, which involve several CaM-dependent kinases and a single CaM-regulated phosphatase, are covered. In addition, CaM has been linked to other events, including Tau aggregation. As a central player in tauopathies, CaM offers several alternative therapeutic routes that are worth investigating. For example, evidence is presented here that supports targeting specific binding motifs of key CaM-regulated Tau kinases as a novel therapeutic approach.