The Structural Biology of Amyloid Aggregation

Lead Research Organisation: University of Leeds
Department Name: Sch of Molecular & Cellular Biology

Abstract

Diseases linked with the aggregation of proteins are a major threat to today's society, especially amongst our ageing population, and the public are today acutely aware of the threats posed by these diseases, which include Alzheimer's and Parkinson's diseases and other degenerative disorders. Proteins are the workhorses of all living organisms. They perform most of the functions required for life, and their dysfunction if left unchecked by the natural defence mechanisms of cells, can be hugely damaging to cellular function and healthy life. From the moment proteins are synthesised, they exist on a knife-edge, wherein changes to their sequence can lead to aggregation and disease. One of the commonest forms of protein misfolding diseases is amyloidosis, and more than 50 different proteins are currently known to cause amyloid diseases that include both rare disorders, such as dialysis-related amyloidosis (DRA), and major societal threats such as Parkinson's disease (PD). Unfortunately we are not able prevent, treat or cure most amyloid diseases and failures of clinical trials mean that we urgently need new inspiration to fire innovative ways of tackling amyloid disease. In this three year project, we will provide new insights into the structures of amyloid fibrils and the mechanism by which they form, hopefully providing a new impetus for therapeutic ideas. The time has never been better to make this step change. By exploiting recent advances in cryo-electron microscopy (cryo-EM), we will answer three fundamentally important and medically relevant questions: (i) how diverse is the amyloid fold, and (ii) how relevant are in vitro models of amyloid aggregation to the structures formed in patients, and (iii) how can we link amyloid sequence and structure to human disease? Working closely with physicians who are expert in systemic and neurodegenerative disorders, and focussing on alpha-synuclein (involved in Parkinson's disease) and beta2-microglobulin (associated with dialysis-related and systemic amyloidoses), we will achieve these aims by determining the 3D structures of amyloid fibrils grown in vitro and comparing them with fibrils extracted from human tissue. Overall, therefore, the work will yield new insights into amyloid structure, stability and function and new understandings of how these fascinating assemblies contribute to the cellular dysfunction that may led to disease.

Technical Summary

This 3-year project grant seeks to better understand amyloid fibril structure, and crucially, to understand how relevant fibrils of recombinant the dynamics and function and how these features contribute to cellular dysfunction and disease. Specifically, we will work with physicians with expertise in neurodegenerative and systemic amyloidosis, focussing on alpha-synuclein (involved in Parkinson's disease) and beta-2-microglobulin (involved in dialysis-related and systemic amyloidosis). Using cryo-EM and single particle image processing methods, together with ssNMR, we will reveal the structures of fibrils formed in vitro and purified ex vivo from patient samples. We we will also use mass spectrometry to understand the post-translational modification state of those ex vivo samples, allowing direct comparison to relevant in vitro fibrils. Building on a plethora of preliminary data that demonstrate the feasibility of the experiments proposed, we will thus address the following fundamental question: How do the structure(s) of amyloid fibrils generated in vitro compare with those formed in vivo? This will reveal new insights about these fascinating molecular assemblies and may inspire new opportunities to develop strategies to combat amyloid disease that harness the new structural insights gained.

Planned Impact

The overarching aim of this five-year MRC programme grant application is to deliver a step-change in our understanding of how proteins aggregate into amyloid fibrils, and how the structures of those fibrils are altered by mutations and post-translational modifications. We believe that such understanding will underpin future efforts to design new therapies that can modulate protein aggregation, either preventing or promoting the formation of amyloid fibrils dependent upon the disease condition in question. In the short-term, the impact of our research will be for researchers interested in protein aggregation, protein folding and amyloidosis, in fields spanning biochemistry, biophysics, degeneration, and structural biology (see Academic Beneficiaries). Crucially, in addition to a fundamental research benefit, the work described focuses on the urgent and growing need to develop new reagents that can combat the ever increasing tide of amyloid diseases such as Parkinson's diseases and systemic amyloidosis.

Given the major importance of diseases involving protein aggregation to human health and wellbeing, major beneficiaries of the research will fall into three categories: (1) industries focusing on the urgent and unmet need for new therapies for amyloidosis; (2) clinicians needing successful treatment options for the wide range of disorders that are underpinned by amyloid aggregation; and (3) patients who require treatment options. The research programme we propose thus fits squarely within the remit of the MRC.

Finally, the research programme will train two researchers in an important and topical field using state-of-the-art approaches, including complex instrumentation, and requiring high level skills in computing and data analysis to understand the results obtained using the techniques described. The researchers employed will thus be well equipped for an industrial career in biotechnology-related fields, in sectors including health and medicine, pharmaceuticals, analytic biophysics and personal care. In addition the PDRAs will be trained in teamwork, problem solving, and communication across disciplines, having been exposed to research in a diverse, large and active research team. These skills are useful for a host of professions outside of the technical disciplines, including management, politics and government, business, and entrepreneurship. Hence the PDRAs employed will be highly employable across a number of different disciplines and environments, ensuring their successful career development, whichever route they choose to take.

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