Target Discovery

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Key steps in the pre-clinical development of a new drug include identifying and validating candidate targets, identifying small molecules that beneficially affect target function and biological phenotypes, characterizing the mechanisms of drug-target interaction, and using medicinal chemistry to enhance desirable therapeutic characteristics and minimize undesirable effects. Our new program integrates biological and medicinal chemistry approaches to focus on cardiovascular target discovery and drug development. 

Key components that we have established are:

  1. Target identification using genetic approaches. We have established high-throughput cell-based screening approaches that use reporter based assays and high-content microscopy to perform phenotypic screens. We have available a variety of siRNA and lentiviral shRNA, and screening facilities at Oxford’s Target Discovery Institute. These approaches can be applied to biological questions. For instance, BMP signaling is an important pathway in cardiac fibrosis, and we have performed siRNA screens of the BMP signaling pathway using a luciferase biosensor to identify suppressors of the pathway (Dr Matt Benson).
  2. Phenotypic screens using small molecules. We have access to several commercial chemical libraries at the Target Discovery Institute, and also our in-house chemical libraries (Dr Angela Russell). These can be used for cell-based phenotypic screens using high-content microscopy. For instance we have performed small molecule phenotypic screens to identify enhancers of endothelial tube formation – using a novel high-throughput assay, that could potentially be of use in therapeutic revascularization (Dr Ayman Al-Haj Zen). We are currently developing screens for epicardial cell differentiation that could have impact on myocardial regeneration (Prof. Paul Riley).
  3. Target validation. We have established in vivo models where a genetically defined target identified in cells can be rapidly tested in vivo using tetracycline-inducible shRNA technology (Dr Ben Davies).  This allows exquisite drug-like control of gene expression, and not only establishes if knockdown of the gene has beneficial effects but also if it has undesirable off target effects1.  In addition we have established other approaches such as TALEN2 and CRISPR that also enable target validation.
  4. Novel approaches for exploring chemical space. Cyclic peptides offer a novel way of exploring chemical space (for instance a 8-mer cyclic peptide library has 208 combinations) and we have utilised cyclic peptide technologies3 to create and screen cyclic peptide libraries against protein targets (Dr Akane Kawamura).
  5. Identification of drug targets. Most drugs exert their effects by binding to protein targets.   Identifying such targets and the mechanism of drug binding can allow medicinal chemists to modify the drug to enhance desirable therapeutic characteristics, and minimize undesirable off-target effects. We are establishing and further developing a yeast 3-hybrid4 technology resource for identifying the protein targets of drugs for which the mechanisms of action are not clearly understood (Mr Graham Davies, Dr Kamayani Singh). This new technology overcomes several limitations of traditional proteomics, such as abundance, solubility, stability and structural conformation of the protein in the cell lysate. The technology is broadly applicable to existing approved drugs where it can be used for therapeutic repurposing; to new small molecules discovered in high-throughput phenotypic screens where the protein target is unknown, enabling chemists to develop structure-activity relationships; and to predicting the off-target effects of small molecules that are in development as therapeutics.
  6. Cardiovascular medicinal chemistry DPhil program. To train a new generation of cardiovascular medicinal chemists we have initiated a 4–year DPhil program where chemistry students are grounded in cardiovascular biology and medicinal chemistry for 2 terms, and then take on 2 rotation projects (with a chemist and a cardiovascular supervisor) after which they choose a jointly supervised DPhil project focusing on a cardiovascular medicinal chemistry / chemical biology problem. Please see the Cardiovascular Medicinal Chemistry DPhil Program site for further details.

PIs involved in this research theme:

Shoumo Bhattacharya - (Theme Leader)

Paul Riley

Angela Russell

Akane Kawamura

Ben Davies

Key References:

  1. Premsrirut, P. K. et al. A rapid and scalable system for studying gene function in mice using conditional RNA interference. Cell 145, 145–158 (2011).
  2. Davies, B. et al. Site specific mutation of the Zic2 locus by microinjection of TALEN mRNA in mouse CD1, C3H and C57BL/6J oocytes. PLoS ONE 8, e60216 (2013).
  3. Passioura, T., Katoh, T., Goto, Y. & Suga, H. Selection-Based Discovery of Druglike Macrocyclic Peptides. Annu. Rev. Biochem. (2014). doi:10.1146/annurev-biochem-060713-035456
  4. Chidley, C., Haruki, H., Pedersen, M. G., Muller, E. & Johnsson, K. A yeast-based screen reveals that sulfasalazine inhibits tetrahydrobiopterin biosynthesis. Nat Chem Biol 7, 375–383 (2011).