• aggregation
• Alzheimer
• drug screening
• FRET
• gene expression
• Nuclear function
• Tau
• Tauopathy

Tau protein is a neuronal microtubule (MT) associated protein whose aggregation is one of the hallmarks of several neurodegenerative diseases known as tauopathies, such as Alzheimer’s disease (AD) and frontotemporal dementia (FTDP-17). At the onset of the pathology, Tau undergoes hyperphosphorylation which leads to destabilisation and detachment from MTs and to an increase in the soluble pool of Tau. Once it is detached from the MTs, the protein is more prone to aggregation so intracellular toxic aggregates deposition starts. Although aggregation has a crucial role in Tau pathology, an increasing body of evidence suggests that some non-canonical functions of Tau can account for some fundamental aspects of the pathology as well.
As a matter of fact, our lab demonstrated that nuclear Tau is able to modulate the expression of the vesicular glutamate transporter VGluT1, which happens to be upregulated in the early phases of tauopathies. Moreover, we demonstrated that the increase in the soluble pool of Tau enhances Tau translocation into the nucleus thus increasing VGluT1 expression. This finding has great relevance since it might describe at the cellular level what happens in the early phases of the disease.
In this thesis, I am investigating the mechanisms underlying this new function of Tau protein. In particular, I am focusing on the hypothesis that Tau might be involved in chromatin remodelling. In fact, it has been found out that Tau interacts with TRIM28 that is a member of a protein complex that includes the histone deacetylase HDAC1. Moreover, I am investigating the effects of the pathological mutation P301L, associated with FTDP-17, and the effects of Tau aggregation on VGluT1 expression.
Nowadays, no disease modifying drugs against tauopathies are available and all the attempts to target other lesions linked to these diseases failed. For this reason, there is an increasing interest in targeting the pathological forms of Tau in order to develop a Tau-centric treatment against tauopathies.
To fill this gap, I set-up an in vitro screening assay to test potential therapeutic molecules against Tau aggregation. The lab recently developed the FRET-based Conformational Sensitive Tau sensor (CST) that allows studying the conformation of Tau protein both in physiological and pathological conditions, thus providing a clear imaging read-out of different features of the aggregates inside the cell.
I exploited the peculiar biophysical properties of CST to screen drugs against Tau pathology. The in vitro assay exploits a CST reporter SH-SY5Y cell line, where Tau aggregation is induced with synthetic Tau seeds. This system tests the ability of candidate compounds to interfere with the process of aggregation or even to revert it.
In conclusion, this thesis focuses on two aspects relevant for Tau pathology: the molecular characterization of a new function for Tau that might be relevant in the early phases of pathology to make it a potential therapeutic target, and the development of an in vitro drug screening to evaluate the therapeutic potential of two candidate compounds.