Stabilization of Monomeric Tau Protein by All D-Enantiomeric Peptide Ligands as Therapeutic Strategy for Alzheimer's Disease and Other Tauopathies.

Alzheimer's disease and other tauopathies are the world's leading causes of dementia and memory loss. These diseases are thought to be caused by the misfolding and aggregation of the intracellular tau protein, ultimately leading to neurodegeneration. The tau protein is involved in a multitude of different neurodegenerative diseases. During the onset of tauopathies, tau undergoes structural changes and posttranslational modifications and aggregates into amyloid fibrils that are able to spread with a prion-like behavior. Up to now, there is no therapeutic agent which effectively controls or reverses the disease. Most of the therapeutics that were developed and underwent clinical trials targeted misfolded or aggregated forms of tau. In the current manuscript, we present the selection and characterization of two all D-enantiomeric peptides that bind monomeric tau protein with a low nanomolar KD, stabilize tau in its monomeric intrinsically disordered conformation, and stop the conversion of monomers into aggregates. We show that the effect of the two all D-enantiomeric peptides is strong enough to stop ongoing tau aggregation in vitro and is able to significantly reduce tau fibril assembly in cell culture. Both compounds may serve as new lead components for the development of therapeutic agents against Alzheimer's disease and other tauopathies.