Formation of Mixed-Isoform Tau Filaments Detected Using Fluorescence-Based in vitro Techniques
As of 2021, Alzheimer's disease is the seventh-leading cause of death in the United States. One pathology of this disease is the accumulation of tau neurofibrillary tangles. Tau is a microtubule-associated protein believed to be a causative factor in Alzheimer's disease as well as other tauopathies. Here, the aggregation of 2N4R and 2N3R was induced with arachidonic acid in vitro to produce a copolymerized structure. To do so, detection of copolymerization is explored through fluorescence applications of split GFP and FRET. The splitting of GFP did not prove to be a viable technique for determining copolymerization because of the inability of these tagged proteins to form acceptable tau filaments. The FRET application provided a useful method for determining the interactive protein-protein properties of 2N4R and 2N3R through the tagging of these isoforms with fluorescent proteins GFP and YPet, respectively. It was established that these two tau isoforms are capable of copolymerizing, leading to the next question, if these aggregates form a structure different from single tau isoform aggregates and if so, whether or not these structures are found in Alzheimer's disease or other tauopathies.