The proteins involved in polyglutamine (PolyQ) diseases, such as Huntingtin (HTT) in Huntington's disease (HD), have peculiar characteristics compared to other pathological proteins. Huntingtin aggregates can be released from affected cells and be picked up by those that are still healthy. These observations have enormous implications for the therapy of Huntington's disease.
In the laboratory, we study the role of some structural aspects of polyQ aggregates in in the diffusion of such aggregates through the brain parenchyma, and the impact of such diffusion on the progression of the disease.
Huntington disease: pathogenic contribution of Huntingtin aggregates
Protein aggregation observed in diseases such as Alzheimer's and Parkinson's is caused by their structural conversion from a native form into a pathological conformation rich in β-sheet type structures. HTT and other polyQ proteins aggregate with a different mechanism, through the formation of supercoiled helixes called coiled-coils (Ccs). CCs mediate protein-protein interactions, and are usually reversible. In the mutated HTT, following the expansion of the polyQ tract, the CC regions become more stable, promoting their aggregation and toxicity. We also observed that CCs are implicated in the intercellular propagation of HTT aggregates. In our studies we will identify the molecular mechanisms underlying these processes, with the goal to identify new therapeutic targets.
Huntington disease: intercellular propagation of Huntingtin aggregates (HTT)
The objective of our research is to study how the intercellular propagation of polyQ aggregates contributes to the progression of HD. It is believed that the late onset of the disease is caused by the age-dependent decline of the cells' ability to properly degrade aggregated proteins. However, another explanation could be that the spread of toxic aggregates in the brain is a limiting factor in the onset of the disease. Therefore, establishing a relationship between aggregation, spread and onset of disease symptoms will be of great importance, especially in the context of a possible therapeutic intervention.
Huntington disease: development of new therapeutic approaches
In this study we want to evaluate the therapeutic potential of an intervention aimed at affecting the CC structure of mutated HTT, to prevent or delay its aggregation. In particular we will examine if: it is possible to interfere with the oligomerization and toxicity of polyQ-CC-HTT in cell cultures and in vivo; and whether it is possible to block the intercellular transfer of the polyQ aggregates.
Front temporal Dementia: development of new cellular models to study the spreading of Tau oligomers
The aggregates of the microtubule-associated protein Tau are a pathological hallmark of tauopathies including front temporal dementia and Alzheimer’s disease. Tau oligomers are considered to be the most toxic species and the likely cause of the spreading of the disorders. Here, using a new cell culture system that we developed, we study the seeding properties and overall effects on cell metabolism of oligomers of the FTD-associated tauP301L mutant. We find that internalized oligomers promote the aggregation of endogenous tauP301L and appear resistant to degradation. The enhanced half-life of the aggregates correlates with a general decrease of proteasome activity and enhanced toxicity. These analyses provide new insights into the molecular determinants of the prion-like mechanism behind the spreading of tau pathology.
International Consensus on Cardiopulmonary Resuscitation.