Setting up antiprions: a screen for prion mutants interfering with endogenous prion aggregation

Abstract

Neurodegeneration and dementia are the principal pathological hallmarks in Alzheimer’s disease (AD). Nowadays, it is known that the main cause of the illness is aggregation and misfolded protein deposition which has the ability to transmit the wrong conformation to native proteins. These proteins are amyloid-β (Aβ) and phosphorylated tau protein that form senile plaques and neurofibrillary tangles (NTF), respectively. That kind of structures are closely related with cellular damage like synaptic and calcium homeostasis dysfunctions, and with oxidative stress that consequently leads to neuronal degeneration. The Aβ protein is a proteolysis cleavage product of the amyloid precursor protein (APP) by the β- and 𝛾�-secretases enzymes in the amyloidogenic pathway that leads to AB peptide formation. Furthermore, this mechanism can generate other APP truncated proteins with different length and toxicity. The Aβ42 form has the greatest ability to form aggregates and, as a result, is more related with the fibril formation, intracellular structures aggregation and causes higher toxicity than the other forms. Taking into account the difficulty of working and growing mammalian cells in culture, the yeast Saccharomyces cerevisiae has been used to develop different models for studying Alzheimer’s disease. These eukaryotic cells are simple and can easily be used in cloning and mutagenesis procedures while, at the same time, they share many molecular and cellular traits with more complex organisms. Thus, yeasts are really useful for the study of the molecular basis of human diseases. Here we use a yeast W303-1A strain expressing the Aβ42 protein tagged in N-Terminal with the green fluorescence protein (GFP) to recapitulate and analyse the intracellular aggregation of Aβ42. Also, it allows us to study the effects of overexpression and protein deposition in the cellular functions and mechanisms. More important for our objectives, yeast cells allow the screening of enormous numbers of substances and peptides that prevent or hinder the formation of Aβ42 aggregates