ERIBA (E. Nollen group): Identification of biological mechanisms that drive age-related protein toxicity
i. Objective of research: To identify the functional role of SERF (small EDRK rich factor) in neurodegenerative diseases.
ii. Current state of the art: Common to ageing and age-related neurodegenerative diseases is the accumulation of toxic, aggregation-prone proteins in aggregates. In the brain, these aggregates may contain disease-specific proteins, such as the α-synuclein in Parkinson’s and amyloid beta in Alzheimer’s disease. Structural conversions in these proteins, prior to their aggregation, are thought to trigger the onset of disease but the biological mechanisms that drive such conversions are poorly understood. Using genetic screens in the nematode C. elegans, we have identified regulators that actively induce such toxic structural changes. These include small, positively charged proteins called MOAG-4/SERF. Depletion of MOAG-4/SERF in C. elegans or of human SERF1 or SERF2 in cell lines suppresses the aggregation and toxicity of transgenically-expressed aggregation-prone proteins but also reduces the abundance of compactly folded aggregation intermediates. These findings suggest that such structural alterations play an important role in toxicity. In cell-free studies, SERF catalyzes aggregation of several amyloid forming disease proteins, but has no effect on aggregation-prone proteins that form other type of aggregates. Whether catalyzing amyloid formation is a physiological function of SERF or whether it is a gain-of-function acquired in presence of aggregation-prone proteins remains to be functionally addressed.
iii. Research methodology and approach: To identify the physiological function of SERF, our ESR will perform a high-throughput proteomics analysis to identify cellular proteins that interact with SERF. Using a recently developed virus-based approach, SERF proteins will be expressed in fusion with HIV-1 GAG protein, which traps SERFs and their interaction partners in virus-like particles (VLPs) that bud off from cells. Enrichment of VLPs will allow for SERF-bound proteins to be identified by mass spectrometry. After validation of the interactions, potential amyloid-forming interactors will be selected by structure predictions and aggregation assays in cells and in test tubes, in the presence or absence of SERFs, using fluorescent tags and amyloid-specific dyes. Functional assays will be performed on a subset of SERF interactors, including proteins that do not form amyloid, to establish how SERF is involved in their physiological functions. These studies will determine whether catalysis of amyloid aggregation is part of the natural function of SERFs or whether it is an acquired function in the presence of aggregation-prone disease proteins.
iv. Originality and innovative aspects of the ESR project: Research on age-related protein toxicity has traditionally been focusing to delineate the cellular mechanisms involved in removing or refolding aggregation-prone proteins for developing therapeutic strategies. Here, we aim to dissect the functional relevance of pathways driving toxic structural changes as potential targets for the development of rationalized intervention strategies against age-related neurodegenerative diseases.
v. Integration of the ESR project to the overall research programme: Our ESR will work on the premature onset of neurodegenerative disorders in TRF2 animal models (with the Gilson group) and NER progeroid animals (with the Garinis group) and with Genevia and ProtATonce on the analysis of proteomics datasets.