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Deciphering the molecular basis of neurodegenerative diseases associated with protein misfolding for the development of novel therapeutics

Periodic Report Summary 2 - NEUROFOLD (Deciphering the molecular basis of neurodegenerative diseases associated with protein misfolding for the development of novel therapeutics)

Protein misfolding and aggregation are intimately associated with a group of disorders believed to result from the failure of proteins to reach their active state or from the accumulation of abnormally folded proteins. Neurodegenerative disorders, such as Alzheimer's, Parkinson's, or Huntington's disease are examples of protein misfolding disorders associated with the accumulation of misfolded proteins in specific regions of the brain. No preventive or neuroprotective strategies exist today for any of these, creating tremendous socio-economic problems and challenges across the globe.

At the Cell and Molecular Neuroscience Unit, Instituto de Medicina Molecular (please see http://imm.fm.ul.pt/web/imm/cellandmolecularneuroscience) our work comprised of a multidisciplinary approach whereby we combined different model systems, bioinformatics, and powerful imaging techniques, to investigate the cellular pathways involved in these diseases. We began by using simple, yet powerful, model systems in which to investigate the normal biology and pathobiology of proteins involved in neurodegenerative disorders associated with protein misfolding.

Initially, we used yeast cells, which have already proven to be valuable 'living test tubes' for these types of studies, providing innovative approaches to tackle these complex diseases. Our studies began to shed light into the molecular mechanisms involved in PD, namely those relating to the cell's ability to handle and process misfolding-prone proteins, and we now hope to continue to validate those mechanisms in animal models, in the hope that we will contribute to the discovery of novel avenues for therapeutic intervention.

The identification of the toxic species leading to neurotoxicity in different neurodegenerative disorders is critical for a thorough understanding of the disease mechanisms. This is was a central aspect of our research. We developed and explored a bimolecular fluorescence complementation system, based on green fluorescent protein, to monitor the initial steps of protein oligomerisation and aggregation. This approach enabled us to conduct a genetic screen to identify cellular pathways involved in the process of alpha-synuclein oligomerisation, a process associated with Parkinson's disease.

In addition, we are also focusing on determining the normal function and biology of proteins involved in these diseases. This knowledge will be essential in order to determine how each protein relates to the pathobiology. In HD, for example, recent evidence suggests that loss of normal huntingtin function is involved in the disease mechanisms. In PD, the recessive nature of some of the mutations associated with familial cases also suggests that loss of function might be at the root of the problems. Thus, we focused on studying the normal biology of proteins such as alpha-synuclein, DJ-1, huntingtin, Tau, and LRRK2, for example, all of which are central players in these disorders.

We also investigated the molecular pathways related to the cytotoxicity caused by these proteins, using different model organisms and approaches. In particular, we are using yeast models, mammalian cell culture models, and in vivo zebrafish and mouse models, since they afford the opportunity to investigate different aspects of the problem. We are employing also a variety of approaches, including state-of-the-art microscopy, genomics, and proteomics, which, in combination, provide detailed molecular information about the underlying biology and pathobiology of the proteins under study.