Abstract

An extensive body of literature suggested a possible role of the microtubule-associated protein Tau in chromatin functions and/or organization in neuronal, non-neuronal, and cancer cells. How Tau functions in these processes remains elusive. Here we report that Tau expression in breast cancer cell lines causes resistance to the anti-cancer effects of histone deacetylase inhibitors, by preventing histone deacetylase inhibitor-inducible gene expression and remodeling of chromatin structure. We identify Tau as a protein recognizing and binding to core histone when H3 and H4 are devoid of any post-translational modifications or acetylated H4 that increases the Tau’s affinity. Consistent with chromatin structure alterations in neurons found in frontotemporal lobar degeneration, Tau mutations did not prevent histone deacetylase-inhibitor-induced higher chromatin structure remodeling by suppressing Tau binding to histones. In addition, we demonstrate that the interaction between Tau and histones prevents further histone H3 post-translational modifications induced by histone deacetylase-inhibitor treatment by maintaining a more compact chromatin structure. Altogether, these results highlight a new cellular role for Tau as a chromatin reader, which opens new therapeutic avenues to exploit Tau biology in neuronal and cancer cells.

Highlights

  • Tau was first described as a neuronal microtubule-associated protein (MAP), regulating microtubule assembly and axonal transport

  • We found that Tau4R was able to maintain PCH structure irrespectively of the observed decrease in H3K9me2 induced by trichostatin A (TSA) or BIX 01294, suggesting an indirect role for Tau4R in maintaining PCH and heterochromatin integrity

  • The mechanism by which TSA reduced the level of this epigenetic mark remains unknown but has been reported previously (Fukuda et al, 2015)

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Summary

Introduction

Tau was first described as a neuronal microtubule-associated protein (MAP), regulating microtubule assembly and axonal transport. The microtubule associated protein tau (MAPT) constitutes a family of six isoforms containing three or four microtubule binding domains (named 3R and 4R, respectively). The 4R isoforms have a higher affinity for microtubules (Wang and Mandelkow, 2016). Tau3R(s) are expressed mostly during development whereas Tau4R becomes the predominant isoform in adult brain. It is thought that the lower affinity of Tau3R for microtubules allows the morphological changes necessary for neuronal differentiation and migration (Lu and Kosik, 2001; Avila et al, 2004; Sergeant et al, 2005). The affinity of Tau for microtubules is tightly regulated by post-translational modifications.

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