Detection of mutations in the binding domain of tau protein by kinesin-microtubule gliding assay

Tau protein is a biomarker for neurodegeneration. The microtubule (MT)-tau binding affinity varies according to the type of tau isoform and their degree of phosphorylation. We have utilized the difference in binding affinity of tau protein to MT to be evaluated by kinesin motor protein based MT gliding system, in order to detect and differentiate tau isoforms and their mutants. Evaluation parameters are landing rate and density of MTs on a kinesin-coated surface, and their strong correlation enables us to measure only landing rate to distinguish 2N3R and 2N4R (tau isoforms) and mutants. Secondly; we designed and fabricated a microstructure to detect tau-attached MTs, which is composed of a reservoir, parallel channels and collectors. Increase of fluorescent intensity by accumulation of MTs over time was successfully detected at the collector areas. Sensitive and rapid MT-kinesin based detection of tau isoforms (3R/4R) and mutated tau proteins on a microchip format will aid in differential diagnosis and early detection of neurodegenerative condition such as Alzheimer disease (AD).