Chemical Tools for Probing Histone Deacetylase Multiprotein Complexes in Disease

The development of new chemical tools and probes is vital to understanding the functions of multifaceted proteins and enzymes in the cell and their role in disease. Many enzymes catalyse chemical modifications to DNA and DNA associated proteins regulating which genes are 'switched on' and 'off', often termed the epigenome. Histone deacetylases (HDAC) are a class of enzyme that remove acetyl groups from DNA associated histone proteins. The presence of many HDAC isoenzymes in the cell, with structural similarity, makes probing these enzymes selectively a challenge. Further to this, the same HDAC isoenzyme can be incorporated as a catalytic sub-unit into a number of much larger multiprotein corepressor complexes, whereby the complex is essential to the distinct biological function of the HDAC. Abnormal HDAC activity is associated with diseases including cancer and Alzheimer's yet current drugs lack HDAC enzyme selectivity and are associated with debilitating side effects.

The proposed research will deliver novel chemical tools designed to modulate HDAC enzymes with multiprotein complex selectivity. Designing compounds to selectively target a specific HDAC complex is a novel approach towards probing the function of such complexes with significant therapeutic potential. This will be achieved by three objectives. Objective one involves the preparation of dual functionalised warhead peptides designed to bind two enzymatic sites simultaneously in a specific complex. Objective two focuses on the development of compounds to facilitate selective degradation of a sub-unit enzyme required for multiprotein complex structural integrity and function. Objective three broadens on the approaches from objective two investigating the synthesis and validation of other compounds to degrade other histone deacetylase enzymes with complex selectivity. The chemical tools developed will have important applications in studying the roles of HDAC multiprotein complexes in disease, and the tools will also be used for future medicinal compound development to treat diseases such as cancer.

Therapeutic agents have been approved by the FDA targeting epigenetic proteins and numerous compounds are currently in clinical trials. The epigenetics market is predicted to be valued at 16.31 billion USD by the year 2022. Considering the application of our tool compounds they will be of significant interest for potential translational funding opportunities, and collaborative opportunities, with the pharmaceutical industry and medical research charities in the UK looking for novel approaches towards drugging targets. This will contribute to the UK's economy in the drug discovery and life sciences sectors. Through a number of LISCB enterprise events such companies and charities will be informed and engaged with the research over, and beyond, the two year period of the proposed project.

Histone deacetylase enzymes and their complexes have been linked to diseases that plague modern day society. These include; cancer, cardiovascular diseases, neurodegenerative diseases such as Alzheimer's and even drug addiction. Cancer and heart disease are one of the top causes of mortality in in the UK. While an aging population has resulted in increasing incidences of neurodegenerative diseases such as Alzheimer's and dementia placing a real burden on carers in society and the NHS. It is envisaged that this research programme will lead to future drugs that will contribute to alleviating the socioeconomic burden caused by these diseases. This will contribute to a significant improvement in UK citizen's quality of life, health and reduced mortality rates. Throughout the project conference presentations, posters, publications and other outputs will be publicised to other scientists and the public by a Hodgkinson research group twitter feed, department of chemistry twitter feed, University of Leicester Yammer site, and the Hodgkinson department of chemistry and LISCB websites. The research will also be highlighted in university open days to prospective students and during university STEM school visits.

The PDRA will gain essential skills and training in multiple aspects of chemical biology. The research will be carried out in the interdisciplinary environment of LISCB. The PDRA will have daily project meetings with the PI and will attend regular joint group meetings between the Hodgkinson, Schwabe and Cowley groups to present their findings. Within the first year of the project the PDRA will have performed and gained skills in; automated peptide synthesis, fluorescence based assays, and hands on experience using cryo-electron microscopy. In the final year the PDRA will advance their synthetic skills and be competent in cell culture experiments and western blotting. This broad skillset will prepare the PDRA for a future career in chemical biology in academia or industry. The PDRA will also have the opportunity to supervise undergraduate and postgraduate students in the Hodgkinson research group gaining management skills. The PDRA will have the opportunity to present at national conferences, including RSC chemical biology meetings, and one international conference. Overall this training will contribute to and strengthen the chemical biology community in the UK.