Isoform-specific antibodies shed light onto distinct role of murine Tau isoforms

Abstract

In the adult murine brain, the microtubule-associated protein Tau exists as three major isoforms, which have four microtubule-binding repeats (4R), with either no (0N), one (1N) or two (2N) amino-terminal inserts. However, little is known about the role of the amino-terminal inserts and how the 0N, 1N and 2N Tau species differ. To investigate this, a series of isoform-specific antibodies were generated and performed a profiling by Western blotting and immunohistochemical analysis using wild-type mice in two months, two weeks and postnatal day 0. 1N isoform strongly localizes to the nucleus, although it is also found in cell bodies and dendrites, but not axons. The 0N isoform is mainly found in cell bodies and axons, whereas nuclei and dendrites are only slightly stained. The 2N isoform is highly expressed in axons and cell bodies, with a detectable expression in dendrites and a slight expression in nuclei. Moreover, the isoform-specific antibodies were used for immunoprecipitation and followed by mass spectrometry analysis to identify Tau-interacting proteins in mouse brain. 101 candidate proteins were identified, including 24 proteins bind preferentially to 0N, 23 proteins preferentially to 1N, 32 proteins preferentially to 2N and 22 proteins show similar binding ratio with three Tau isoforms. Together these findings reveal significant differences between the three murine Tau isoforms. Those new interactions detected in this study offer valuable insight into the Tau’s protein interaction network which could enhance our understanding of Tau.