register interest

Professor Paul Brennan

Research Area: Drug Discovery
Technology Exchange: Drug discovery
Keywords: Medicinal Chemistry, Epigenetics, Chemical Probes, Target Discovery, Structure-Based Design, Fragment-Based Drug Discovery, Parallel Organic Synthesis, Bromodomains, Lysine Demethylases and PHD Fingers
Web Links:
Figure 1.  Target discovery is the first step in drug discovery
A. Comparison of the genes of diseased versus healthy cells can uncover new drug targets.  B.  RNA interference (RNAi) can show that a potential drug target (red) is responsible for the disease.  C. A chemical probe can show that a single region of the drug target (red crescent) is the culprit and the probe can be optimised to give a new medicine.

Figure 1. Target discovery is the first step in drug discovery A. Comparison of the genes of ...

Figure 2.  Epigenetic marks on histones
A lysine demethylases (KDM, red hexagon) removes an epigenetic mark (red) from histone (green).  A plant-homeodomain (PHD, red crescent) reads the epigenetic mark. A bromodomain (BRD, purple crescent) reads another epigenetic mark (purple).  The epigenetic marks regulate the gene encoded in the DNA (blue).

Figure 2. Epigenetic marks on histones A lysine demethylases (KDM, red hexagon) removes an ...

Epigenetic Chemical Probes in Drug Discovery

The major cause of failure in discovery of new medicines is due to a fundamental lack of understanding of the biology of disease.  The likelihood of a new medicine having a positive effect when tested in patients for the first time is less than 30%.  In order to find new medicines for diseases, like Alzheimer’s disease, cancer and chronic inflammation, we first need to discover a new novel disease-associated protein target.   Following on from the discovery of a target, drug discovery is aimed at finding safe, effective means of modifying the target’s detrimental effects in disease.

Target Discovery currently uses a number of tools to associate a protein target with a disease: genetic comparisons of diseased versus healthy individuals (figure 1A); inhibition of every possible expressed gene in a cellular model of a disease (a process known as RNA interference - RNAi, figure 1B); or the use of chemical probes in cellular or animal disease models (figure 1C).  None of these approaches is perfect. Genetic comparisons are confounded by functional redundancy of genes, multiplicity of genetic effects and environmental factors. RNA interference removes an entire protein target when only a small piece of it may be important in the disease and the rest is necessary for normal, healthy functions. 

Chemical probes are available for only a small fraction of potential disease targets and are usually less specific than RNAi.  The scarcity of chemical probes is disappointing as they are especially useful; a probe that shows a positive effect can also serve as a chemical starting point for drug discovery.  If genetic or RNA interference methods identify an exciting disease target, it may still take many years to find a chemical starting point to move from target discovery to drug discovery, whereas using a chemical probe in target discovery jump-starts the process.

Epigenetics is an exciting new arena for target discovery.  Classically epigenetics is defined as the transfer of heritable traits from parent to off-spring other than by genetic means.  Understanding of the molecular processes of the epigenetic phenomena has led to an expanded definition.  Epigenetics can now be thought of as the control of gene expression via chemical marks which are written, read and erased by regulating proteins.  The largest variety of epigenetic marks is written on histones (figure 2).  Histones are proteins necessary to accomplish one of nature’s greatest feats: packaging two metres of DNA into a single cell which is 0.00001% as long.  Like a spool, the long threads of DNA (blue in figure 2) are wrapped around a histone core (green in figure 2).  Histones not only package the DNA, but they also control it.  In our thread and spool analogy, the spool can be programmed with epigenetic enzymes to decide when the thread should be unwound and used in gene transcription. 

Epigenetic control of genes is a complex system of regulation by hundreds of enzymes that have multiple functions.  There are multiple epigenetic chemical marks and the combination of marks creates an epigenetic code, similar in concept but even more complex than the genetic code of DNA.  Since problems with control of gene expression are fundamental to many diseases, for example cancer, inflammation and neurological conditions, and enzymes control is the most common action of medicines, epigenetics offers a fortuitous meeting of disease biology with drug discovery capabilities and is generating unprecedented excitement in the global medical research community.  But target discovery in epigenetics is more difficult than other areas.  There is limited evidence from genetic comparisons of important epigenetic targets.  It is hard to interpret the results of RNAi experiments as the entire enzyme is removed and epigenetic enzymes have multiple regions with multiple purposes.  The few successful epigenetic drugs which are known affect only a single enzyme region.  What the field of epigenetic drug discovery desperately needs is the chemical probes to use in target discovery.

Research in our group is focussed on discovery of chemical probes for three classes of epigenetic enzymes, lysine demethylases (KDM, red hexagon in figure 2), plant-homeodomains (PHD, red crescent in figure 2) and bromodomains (BRD​, purple crescent in figure 2).  There are over twenty KDMs and they collectively erase chemical marks important in gene regulation.  One of the KDMs, KDM4B is potentially import in breast cancer and the chemical probe my research group is developing will provide a chemical starting point for drug discovery if it proves the link between KDM4B and breast cancer.  PHDs read the same chemical mark that is erased by KDMs.  Reading of the epigenetic mark by PHDs is involved in gene transcription but there are hundreds of PHDs and the biology of most is a mystery.  There are more than sixty BRDs and they recognize a different epigenetic mark to the KDM/PHD system.  At least some of the BRDs are involved in many cancers.

Our Medicinal Chemistry group utilises high-throughput and fragment-basedscreening to discover chemical leads.  The leads are optimised for potency, selectivity and cellular activity via iterative cycles of structure based drug design, parallel organic synthesis, biophysical testing and compound structure-activity relationship (SAR) analysis.

The chemical probes developed in the group will decipher the function of epigenetic proteins in disease and provide starting points for drug discovery.  By using epigenetic chemical probes in target discovery, we will dramatically accelerate drug discovery in one of the most promising new areas of biomedical research.

Name Department Institution Country
Professor Christopher Schofield Chemistry Oxford University United Kingdom
Dr Stuart Conway Department of Chemistry University of Oxford United Kingdom
Professor Darren Dixon Department of Chemistry University of Oxford United Kingdom
Dr Martin Smith Department of Chemistry University of Oxford United Kingdom
Professor Steven Ley FRS Department of Chemistry University of Cambridge United Kingdom
Professor Julian Blagg Division of Cancer Therapeutics Institute of Cancer Research United Kingdom
Bradley AR, Echalier A, Fairhead M, Strain-Damerell C, Brennan P, Bullock AN, Burgess-Brown NA, Carpenter EP, Gileadi O, Marsden BD et al. 2017. The SGC beyond structural genomics: redefining the role of 3D structures by coupling genomic stratification with fragment-based discovery. Essays Biochem, 61 (5), pp. 495-503. | Show Abstract | Read more

The ongoing explosion in genomics data has long since outpaced the capacity of conventional biochemical methodology to verify the large number of hypotheses that emerge from the analysis of such data. In contrast, it is still a gold-standard for early phenotypic validation towards small-molecule drug discovery to use probe molecules (or tool compounds), notwithstanding the difficulty and cost of generating them. Rational structure-based approaches to ligand discovery have long promised the efficiencies needed to close this divergence; in practice, however, this promise remains largely unfulfilled, for a host of well-rehearsed reasons and despite the huge technical advances spearheaded by the structural genomics initiatives of the noughties. Therefore the current, fourth funding phase of the Structural Genomics Consortium (SGC), building on its extensive experience in structural biology of novel targets and design of protein inhibitors, seeks to redefine what it means to do structural biology for drug discovery. We developed the concept of a Target Enabling Package (TEP) that provides, through reagents, assays and data, the missing link between genetic disease linkage and the development of usefully potent compounds. There are multiple prongs to the ambition: rigorously assessing targets' genetic disease linkages through crowdsourcing to a network of collaborating experts; establishing a systematic approach to generate the protocols and data that comprise each target's TEP; developing new, X-ray-based fragment technologies for generating high quality chemical matter quickly and cheaply; and exploiting a stringently open access model to build multidisciplinary partnerships throughout academia and industry. By learning how to scale these approaches, the SGC aims to make structures finally serve genomics, as originally intended, and demonstrate how 3D structures systematically allow new modes of druggability to be discovered for whole classes of targets.

Gerken PA, Wolstenhulme JR, Tumber A, Hatch SB, Zhang Y, Müller S, Chandler SA, Mair B, Li F, Nijman SMB et al. 2017. Discovery of a Highly Selective Cell-Active Inhibitor of the Histone Lysine Demethylases KDM2/7. Angew Chem Int Ed Engl, 56 (49), pp. 15555-15559. | Show Abstract | Read more

Histone lysine demethylases (KDMs) are of critical importance in the epigenetic regulation of gene expression, yet there are few selective, cell-permeable inhibitors or suitable tool compounds for these enzymes. We describe the discovery of a new class of inhibitor that is highly potent towards the histone lysine demethylases KDM2A/7A. A modular synthetic approach was used to explore the chemical space and accelerate the investigation of key structure-activity relationships, leading to the development of a small molecule with around 75-fold selectivity towards KDM2A/7A versus other KDMs, as well as cellular activity at low micromolar concentrations.

Meier JC, Tallant C, Fedorov O, Witwicka H, Hwang S-Y, van Stiphout RG, Lambert J-P, Rogers C, Yapp C, Gerstenberger BS et al. 2017. Selective Targeting of Bromodomains of the Bromodomain-PHD Fingers Family Impairs Osteoclast Differentiation. ACS Chem Biol, 12 (10), pp. 2619-2630. | Show Abstract | Read more

Histone acetyltransferases of the MYST family are recruited to chromatin by BRPF scaffolding proteins. We explored functional consequences and the therapeutic potential of inhibitors targeting acetyl-lysine dependent protein interaction domains (bromodomains) present in BRPF1-3 in bone maintenance. We report three potent and selective inhibitors: one (PFI-4) with high selectivity for the BRPF1B isoform and two pan-BRPF bromodomain inhibitors (OF-1, NI-57). The developed inhibitors displaced BRPF bromodomains from chromatin and did not inhibit cell growth and proliferation. Intriguingly, the inhibitors impaired RANKL-induced differentiation of primary murine bone marrow cells and human primary monocytes into bone resorbing osteoclasts by specifically repressing transcriptional programs required for osteoclastogenesis. The data suggest a key role of BRPF in regulating gene expression during osteoclastogenesis, and the excellent druggability of these bromodomains may lead to new treatment strategies for patients suffering from bone loss or osteolytic malignant bone lesions.

Igoe N, Bayle ED, Tallant C, Fedorov O, Meier JC, Savitsky P, Rogers C, Morias Y, Scholze S, Boyd H et al. 2017. Design of a Chemical Probe for the Bromodomain and Plant Homeodomain Finger-Containing (BRPF) Family of Proteins. J Med Chem, 60 (16), pp. 6998-7011. | Show Abstract | Read more

The bromodomain and plant homeodomain finger-containing (BRPF) family are scaffolding proteins important for the recruitment of histone acetyltransferases of the MYST family to chromatin. Here, we describe NI-57 (16) as new pan-BRPF chemical probe of the bromodomain (BRD) of the BRPFs. Inhibitor 16 preferentially bound the BRD of BRPF1 and BRPF2 over BRPF3, whereas binding to BRD9 was weaker. Compound 16 has excellent selectivity over nonclass IV BRD proteins. Target engagement of BRPF1B and BRPF2 with 16 was demonstrated in nanoBRET and FRAP assays. The binding of 16 to BRPF1B was rationalized through an X-ray cocrystal structure determination, which showed a flipped binding orientation when compared to previous structures. We report studies that show 16 has functional activity in cellular assays by modulation of the phenotype at low micromolar concentrations in both cancer and inflammatory models. Pharmacokinetic data for 16 was generated in mouse with single dose administration showing favorable oral bioavailability.

Roberts TC, Etxaniz U, Dall'Agnese A, Wu S-Y, Chiang C-M, Brennan PE, Wood MJA, Puri PL. 2017. BRD3 and BRD4 BET Bromodomain Proteins Differentially Regulate Skeletal Myogenesis. Sci Rep, 7 (1), pp. 6153. | Show Abstract | Read more

Myogenic differentiation proceeds through a highly coordinated cascade of gene activation that necessitates epigenomic changes in chromatin structure. Using a screen of small molecule epigenetic probes we identified three compounds which inhibited myogenic differentiation in C2C12 myoblasts; (+)-JQ1, PFI-1, and Bromosporine. These molecules target Bromodomain and Extra Terminal domain (BET) proteins, which are epigenetic readers of acetylated histone lysine tail residues. BETi-mediated anti-myogenic effects were also observed in a model of MYOD1-mediated myogenic conversion of human fibroblasts, and in primary mouse and human myoblasts. All three BET proteins BRD2, BRD3 and BRD4 exhibited distinct and dynamic patterns of protein expression over the course of differentiation without concomitant changes in mRNA levels, suggesting that BET proteins are regulated at the post-transcriptional level. Specific BET protein knockdown by RNA interference revealed that BRD4 was required for myogenic differentiation, whereas BRD3 down-regulation resulted in enhanced myogenic differentiation. ChIP experiments revealed a preferential binding of BRD4 to the Myog promoter during C2C12 myoblast differentiation, co-incident with increased levels of H3K27 acetylation. These results have identified an essential role for BET proteins in the regulation of skeletal myogenesis, and assign distinct functions to BRD3 and BRD4.

Denny RA, Flick AC, Coe J, Langille J, Basak A, Liu S, Stock I, Sahasrabudhe P, Bonin P, Hay DA et al. 2017. Structure-Based Design of Highly Selective Inhibitors of the CREB Binding Protein Bromodomain. J Med Chem, 60 (13), pp. 5349-5363. | Show Abstract | Read more

Chemical probes are required for preclinical target validation to interrogate novel biological targets and pathways. Selective inhibitors of the CREB binding protein (CREBBP)/EP300 bromodomains are required to facilitate the elucidation of biology associated with these important epigenetic targets. Medicinal chemistry optimization that paid particular attention to physiochemical properties delivered chemical probes with desirable potency, selectivity, and permeability attributes. An important feature of the optimization process was the successful application of rational structure-based drug design to address bromodomain selectivity issues (particularly against the structurally related BRD4 protein).

Kawamura A, Münzel M, Kojima T, Yapp C, Bhushan B, Goto Y, Tumber A, Katoh T, King ONF, Passioura T et al. 2017. Highly selective inhibition of histone demethylases by de novo macrocyclic peptides. Nat Commun, 8 pp. 14773. | Show Abstract | Read more

The JmjC histone demethylases (KDMs) are linked to tumour cell proliferation and are current cancer targets; however, very few highly selective inhibitors for these are available. Here we report cyclic peptide inhibitors of the KDM4A-C with selectivity over other KDMs/2OG oxygenases, including closely related KDM4D/E isoforms. Crystal structures and biochemical analyses of one of the inhibitors (CP2) with KDM4A reveals that CP2 binds differently to, but competes with, histone substrates in the active site. Substitution of the active site binding arginine of CP2 to N-ɛ-trimethyl-lysine or methylated arginine results in cyclic peptide substrates, indicating that KDM4s may act on non-histone substrates. Targeted modifications to CP2 based on crystallographic and mass spectrometry analyses results in variants with greater proteolytic robustness. Peptide dosing in cells manifests KDM4A target stabilization. Although further development is required to optimize cellular activity, the results reveal the feasibility of highly selective non-metal chelating, substrate-competitive inhibitors of the JmjC KDMs.

Tumber A, Nuzzi A, Hookway ES, Hatch SB, Velupillai S, Johansson C, Kawamura A, Savitsky P, Yapp C, Szykowska A et al. 2017. Potent and Selective KDM5 Inhibitor Stops Cellular Demethylation of H3K4me3 at Transcription Start Sites and Proliferation of MM1S Myeloma Cells. Cell Chem Biol, 24 (3), pp. 371-380. | Show Abstract | Read more

Methylation of lysine residues on histone tail is a dynamic epigenetic modification that plays a key role in chromatin structure and gene regulation. Members of the KDM5 (also known as JARID1) sub-family are 2-oxoglutarate (2-OG) and Fe2+-dependent oxygenases acting as histone 3 lysine 4 trimethyl (H3K4me3) demethylases, regulating proliferation, stem cell self-renewal, and differentiation. Here we present the characterization of KDOAM-25, an inhibitor of KDM5 enzymes. KDOAM-25 shows biochemical half maximal inhibitory concentration values of <100 nM for KDM5A-D in vitro, high selectivity toward other 2-OG oxygenases sub-families, and no off-target activity on a panel of 55 receptors and enzymes. In human cell assay systems, KDOAM-25 has a half maximal effective concentration of ∼50 μM and good selectivity toward other demethylases. KDM5B is overexpressed in multiple myeloma and negatively correlated with the overall survival. Multiple myeloma MM1S cells treated with KDOAM-25 show increased global H3K4 methylation at transcriptional start sites and impaired proliferation.

Hatch SB, Yapp C, Montenegro RC, Savitsky P, Gamble V, Tumber A, Ruda GF, Bavetsias V, Fedorov O, Atrash B et al. 2017. Assessing histone demethylase inhibitors in cells: lessons learned. Epigenetics Chromatin, 10 (1), pp. 9. | Show Abstract | Read more

BACKGROUND: Histone lysine demethylases (KDMs) are of interest as drug targets due to their regulatory roles in chromatin organization and their tight associations with diseases including cancer and mental disorders. The first KDM inhibitors for KDM1 have entered clinical trials, and efforts are ongoing to develop potent, selective and cell-active 'probe' molecules for this target class. Robust cellular assays to assess the specific engagement of KDM inhibitors in cells as well as their cellular selectivity are a prerequisite for the development of high-quality inhibitors. Here we describe the use of a high-content cellular immunofluorescence assay as a method for demonstrating target engagement in cells. RESULTS: A panel of assays for the Jumonji C subfamily of KDMs was developed to encompass all major branches of the JmjC phylogenetic tree. These assays compare compound activity against wild-type KDM proteins to a catalytically inactive version of the KDM, in which residues involved in the active-site iron coordination are mutated to inactivate the enzyme activity. These mutants are critical for assessing the specific effect of KDM inhibitors and for revealing indirect effects on histone methylation status. The reported assays make use of ectopically expressed demethylases, and we demonstrate their use to profile several recently identified classes of KDM inhibitors and their structurally matched inactive controls. The generated data correlate well with assay results assessing endogenous KDM inhibition and confirm the selectivity observed in biochemical assays with isolated enzymes. We find that both cellular permeability and competition with 2-oxoglutarate affect the translation of biochemical activity to cellular inhibition. CONCLUSIONS: High-content-based immunofluorescence assays have been established for eight KDM members of the 2-oxoglutarate-dependent oxygenases covering all major branches of the JmjC-KDM phylogenetic tree. The usage of both full-length, wild-type and catalytically inactive mutant ectopically expressed protein, as well as structure-matched inactive control compounds, allowed for detection of nonspecific effects causing changes in histone methylation as a result of compound toxicity. The developed assays offer a histone lysine demethylase family-wide tool for assessing KDM inhibitors for cell activity and on-target efficacy. In addition, the presented data may inform further studies to assess the cell-based activity of histone lysine methylation inhibitors.

Igoe N, Bayle ED, Fedorov O, Tallant C, Savitsky P, Rogers C, Owen DR, Deb G, Somervaille TCP, Andrews DM et al. 2017. Design of a Biased Potent Small Molecule Inhibitor of the Bromodomain and PHD Finger-Containing (BRPF) Proteins Suitable for Cellular and in Vivo Studies. J Med Chem, 60 (2), pp. 668-680. | Show Abstract | Read more

The BRPF (bromodomain and PHD finger-containing) family are scaffolding proteins important for the recruitment of histone acetyltransferases of the MYST family to chromatin. Evaluation of the BRPF family as a potential drug target is at an early stage although there is an emerging understanding of a role in acute myeloid leukemia (AML). We report the optimization of fragment hit 5b to 13-d as a biased, potent inhibitor of the BRD of the BRPFs with excellent selectivity over nonclass IV BRD proteins. Evaluation of 13-d in a panel of cancer cell lines showed a selective inhibition of proliferation of a subset of AML lines. Pharmacokinetic studies established that 13-d had properties compatible with oral dosing in mouse models of disease (Fpo 49%). We propose that NI-42 (13-d) is a new chemical probe for the BRPFs suitable for cellular and in vivo studies to explore the fundamental biology of these proteins.

Moustakim M, Clark PGK, Trulli L, Fuentes de Arriba AL, Ehebauer MT, Chaikuad A, Murphy EJ, Mendez-Johnson J, Daniels D, Hou C-FD et al. 2017. Discovery of a PCAF Bromodomain Chemical Probe. Angew Chem Int Ed Engl, 56 (3), pp. 827-831. | Show Abstract | Read more

The p300/CBP-associated factor (PCAF) and related GCN5 bromodomain-containing lysine acetyl transferases are members of subfamily I of the bromodomain phylogenetic tree. Iterative cycles of rational inhibitor design and biophysical characterization led to the discovery of the triazolopthalazine-based L-45 (dubbed L-Moses) as the first potent, selective, and cell-active PCAF bromodomain (Brd) inhibitor. Synthesis from readily available (1R,2S)-(-)-norephedrine furnished L-45 in enantiopure form. L-45 was shown to disrupt PCAF-Brd histone H3.3 interaction in cells using a nanoBRET assay, and a co-crystal structure of L-45 with the homologous Brd PfGCN5 from Plasmodium falciparum rationalizes the high selectivity for PCAF and GCN5 bromodomains. Compound L-45 shows no observable cytotoxicity in peripheral blood mononuclear cells (PBMC), good cell-permeability, and metabolic stability in human and mouse liver microsomes, supporting its potential for in vivo use.

Picaud S, Leonards K, Lambert J-P, Dovey O, Wells C, Fedorov O, Monteiro O, Fujisawa T, Wang C-Y, Lingard H et al. 2016. Promiscuous targeting of bromodomains by bromosporine identifies BET proteins as master regulators of primary transcription response in leukemia. Sci Adv, 2 (10), pp. e1600760. | Show Abstract | Read more

Bromodomains (BRDs) have emerged as compelling targets for cancer therapy. The development of selective and potent BET (bromo and extra-terminal) inhibitors and their significant activity in diverse tumor models have rapidly translated into clinical studies and have motivated drug development efforts targeting non-BET BRDs. However, the complex multidomain/subunit architecture of BRD protein complexes complicates predictions of the consequences of their pharmacological targeting. To address this issue, we developed a promiscuous BRD inhibitor [bromosporine (BSP)] that broadly targets BRDs (including BETs) with nanomolar affinity, creating a tool for the identification of cellular processes and diseases where BRDs have a regulatory function. As a proof of principle, we studied the effects of BSP on leukemic cell lines known to be sensitive to BET inhibition and found, as expected, strong antiproliferative activity. Comparison of the modulation of transcriptional profiles by BSP after a short exposure to the inhibitor resulted in a BET inhibitor signature but no significant additional changes in transcription that could account for inhibition of other BRDs. Thus, nonselective targeting of BRDs identified BETs, but not other BRDs, as master regulators of context-dependent primary transcription response.

Popp TA, Tallant C, Rogers C, Fedorov O, Brennan PE, Müller S, Knapp S, Bracher F. 2016. Development of Selective CBP/P300 Benzoxazepine Bromodomain Inhibitors. J Med Chem, 59 (19), pp. 8889-8912. | Show Abstract | Read more

CBP (CREB (cAMP responsive element binding protein) binding protein (CREBBP)) and P300 (adenovirus E1A-associated 300 kDa protein) are two closely related histone acetyltransferases (HATs) that play a key role in the regulation of gene transcription. Both proteins contain a bromodomain flanking the HAT catalytic domain that is important for the targeting of CBP/P300 to chromatin and which offeres an opportunity for the development of protein-protein interaction inhibitors. Here we present the development of CBP/P300 bromodomain inhibitors with 2,3,4,5-tetrahydro-1,4-benzoxazepine backbone, an N-acetyl-lysine mimetic scaffold that led to the recent development of the chemical probe I-CBP112. We present comprehensive SAR of this inhibitor class as well as demonstration of cellular on target activity of the most potent and selective inhibitor TPOP146, which showed 134 nM affinity for CBP with excellent selectivity over other bromodomains.

Moustakim M, Clark PGK, Hay DA, Dixon DJ, Brennan PE. 2016. Chemical probes and inhibitors of bromodomains outside the BET family MEDCHEMCOMM, 7 (12), pp. 2246-2264. | Read more

Vukovic S, Brennan PE, Huggins DJ. 2016. Exploring the role of water in molecular recognition: predicting protein ligandability using a combinatorial search of surface hydration sites. J Phys Condens Matter, 28 (34), pp. 344007. | Show Abstract | Read more

The interaction between any two biological molecules must compete with their interaction with water molecules. This makes water the most important molecule in medicine, as it controls the interactions of every therapeutic with its target. A small molecule binding to a protein is able to recognize a unique binding site on a protein by displacing bound water molecules from specific hydration sites. Quantifying the interactions of these water molecules allows us to estimate the potential of the protein to bind a small molecule. This is referred to as ligandability. In the study, we describe a method to predict ligandability by performing a search of all possible combinations of hydration sites on protein surfaces. We predict ligandability as the summed binding free energy for each of the constituent hydration sites, computed using inhomogeneous fluid solvation theory. We compared the predicted ligandability with the maximum observed binding affinity for 20 proteins in the human bromodomain family. Based on this comparison, it was determined that effective inhibitors have been developed for the majority of bromodomains, in the range from 10 to 100 nM. However, we predict that more potent inhibitors can be developed for the bromodomains BPTF and BRD7 with relative ease, but that further efforts to develop inhibitors for ATAD2 will be extremely challenging. We have also made predictions for the 14 bromodomains with no reported small molecule K d values by isothermal titration calorimetry. The calculations predict that PBRM1(1) will be a challenging target, while others such as TAF1L(2), PBRM1(4) and TAF1(2), should be highly ligandable. As an outcome of this work, we assembled a database of experimental maximal K d that can serve as a community resource assisting medicinal chemistry efforts focused on BRDs. Effective prediction of ligandability would be a very useful tool in the drug discovery process.

Montenegro RC, Clark PGK, Howarth A, Wan X, Ceroni A, Siejka P, Nunez-Alonso GA, Monteiro O, Rogers C, Gamble V et al. 2016. BET inhibition as a new strategy for the treatment of gastric cancer. Oncotarget, 7 (28), pp. 43997-44012. | Show Abstract | Read more

Gastric cancer is one of the most common malignancies and a leading cause of cancer death worldwide. The prognosis of stomach cancer is generally poor as this cancer is not very sensitive to commonly used chemotherapies. Epigenetic modifications play a key role in gastric cancer and contribute to the development and progression of this malignancy. In order to explore new treatment options in this target area we have screened a library of epigenetic inhibitors against gastric cancer cell lines and identified inhibitors for the BET family of bromodomains as potent inhibitors of gastric cancer cell proliferations. Here we show that both the pan-BET inhibitor (+)-JQ1 as well as a newly developed specific isoxazole inhibitor, PNZ5, showed potent inhibition of gastric cancer cell growth. Intriguingly, we found differences in the antiproliferative response between gastric cancer cells tested derived from Brazilian patients as compared to those from Asian patients, the latter being largely resistant to BET inhibition. As BET inhibitors are entering clinical trials these findings provide the first starting point for future therapies targeting gastric cancer.

Nowak RP, Tumber A, Johansson C, Che KH, Brennan P, Owen D, Oppermann U. 2016. Advances and challenges in understanding histone demethylase biology. Curr Opin Chem Biol, 33 pp. 151-159. | Show Abstract | Read more

Within the last decade we have witnessed significant progress in the field of chromatin methylation, ranging from the discovery that chromatin methylation is reversible, to the identification of two classes of oxidative chromatin demethylases. Multiple genetic and cellular studies emphasize the role of members of the amine oxidase and 2-oxoglutarate oxygenase enzyme families involved in methyl-lysine in physiology and disease. Advances in understanding of the underlying biochemistry have resulted in development of first series of clinical inhibitors and tool compounds which continue to resolve and help understand the complex relationships between chromatin modification, control of gene expression and metabolic states.

Johansson C, Velupillai S, Tumber A, Szykowska A, Hookway ES, Nowak RP, Strain-Damerell C, Gileadi C, Philpott M, Burgess-Brown N et al. 2016. Structural analysis of human KDM5B guides histone demethylase inhibitor development. Nat Chem Biol, 12 (7), pp. 539-545. | Show Abstract | Read more

Members of the KDM5 (also known as JARID1) family are 2-oxoglutarate- and Fe(2+)-dependent oxygenases that act as histone H3K4 demethylases, thereby regulating cell proliferation and stem cell self-renewal and differentiation. Here we report crystal structures of the catalytic core of the human KDM5B enzyme in complex with three inhibitor chemotypes. These scaffolds exploit several aspects of the KDM5 active site, and their selectivity profiles reflect their hybrid features with respect to the KDM4 and KDM6 families. Whereas GSK-J1, a previously identified KDM6 inhibitor, showed about sevenfold less inhibitory activity toward KDM5B than toward KDM6 proteins, KDM5-C49 displayed 25-100-fold selectivity between KDM5B and KDM6B. The cell-permeable derivative KDM5-C70 had an antiproliferative effect in myeloma cells, leading to genome-wide elevation of H3K4me3 levels. The selective inhibitor GSK467 exploited unique binding modes, but it lacked cellular potency in the myeloma system. Taken together, these structural leads deliver multiple starting points for further rational and selective inhibitor design.

Sutherell CL, Tallant C, Monteiro OP, Yapp C, Fuchs JE, Fedorov O, Siejka P, Müller S, Knapp S, Brenton JD et al. 2016. Identification and Development of 2,3-Dihydropyrrolo[1,2-a]quinazolin-5(1H)-one Inhibitors Targeting Bromodomains within the Switch/Sucrose Nonfermenting Complex. J Med Chem, 59 (10), pp. 5095-5101. | Show Abstract | Read more

Bromodomain containing proteins PB1, SMARCA4, and SMARCA2 are important components of SWI/SNF chromatin remodeling complexes. We identified bromodomain inhibitors that target these proteins and display unusual binding modes involving water displacement from the KAc binding site. The best compound binds the fifth bromodomain of PB1 with a KD of 124 nM, SMARCA2B and SMARCA4 with KD values of 262 and 417 nM, respectively, and displays excellent selectivity over bromodomains other than PB1, SMARCA2, and SMARCA4.

Gerstenberger BS, Trzupek JD, Tallant C, Fedorov O, Filippakopoulos P, Brennan PE, Fedele V, Martin S, Picaud S, Rogers C et al. 2016. Identification of a Chemical Probe for Family VIII Bromodomains through Optimization of a Fragment Hit. J Med Chem, 59 (10), pp. 4800-4811. | Show Abstract | Read more

The acetyl post-translational modification of chromatin at selected histone lysine residues is interpreted by an acetyl-lysine specific interaction with bromodomain reader modules. Here we report the discovery of the potent, acetyl-lysine-competitive, and cell active inhibitor PFI-3 that binds to certain family VIII bromodomains while displaying significant, broader bromodomain family selectivity. The high specificity of PFI-3 for family VIII was achieved through a novel bromodomain binding mode of a phenolic headgroup that led to the unusual displacement of water molecules that are generally retained by most other bromodomain inhibitors reported to date. The medicinal chemistry program that led to PFI-3 from an initial fragment screening hit is described in detail, and additional analogues with differing family VIII bromodomain selectivity profiles are also reported. We also describe the full pharmacological characterization of PFI-3 as a chemical probe, along with phenotypic data on adipocyte and myoblast cell differentiation assays.

Mathea S, Abdul Azeez KR, Salah E, Tallant C, Wolfreys F, Konietzny R, Fischer R, Lou HJ, Brennan PE, Schnapp G et al. 2016. Structure of the Human Protein Kinase ZAK in Complex with Vemurafenib. ACS Chem Biol, 11 (6), pp. 1595-1602. | Show Abstract | Read more

The mixed lineage kinase ZAK is a key regulator of the MAPK pathway mediating cell survival and inflammatory response. ZAK is targeted by several clinically approved kinase inhibitors, and inhibition of ZAK has been reported to protect from doxorubicin-induced cardiomyopathy. On the other hand, unintended targeting of ZAK has been linked to severe adverse effects such as the development of cutaneous squamous cell carcinoma. Therefore, both specific inhibitors of ZAK, as well as anticancer drugs lacking off-target activity against ZAK, may provide therapeutic benefit. Here, we report the first crystal structure of ZAK in complex with the B-RAF inhibitor vemurafenib. The cocrystal structure displayed a number of ZAK-specific features including a highly distorted P loop conformation enabling rational inhibitor design. Positional scanning peptide library analysis revealed a unique substrate specificity of the ZAK kinase including unprecedented preferences for histidine residues at positions -1 and +2 relative to the phosphoacceptor site. In addition, we screened a library of clinical kinase inhibitors identifying several inhibitors that potently inhibit ZAK, demonstrating that this kinase is commonly mistargeted by currently used anticancer drugs.

Clark PGK, Dixon DJ, Brennan PE. 2016. Development of chemical probes for the bromodomains of BRD7 and BRD9. Drug Discov Today Technol, 19 pp. 73-80. | Show Abstract | Read more

The bromodomain family of proteins are 'readers' of acetylated lysines of histones, a key mark in the epigenetic code of gene regulation. Without high quality chemical probes with which to study these proteins, their biological function, and potential use in therapeutics, remains unknown. Recently, a number of chemical ligands were reported for the previously unprobed bromodomain proteins BRD7 and BRD9. Herein the development and characterisation of probes against these proteins is detailed, including the preliminary biological activity of BRD7 and BRD9 assessed using these probes. Future studies utilising these chemically-diverse compounds in parallel will allow for a confident assessment of the role of BRD7/9, and give multiple entry points into any subsequent pharmaceutical programs.

Cox OB, Krojer T, Collins P, Monteiro O, Talon R, Bradley A, Fedorov O, Amin J, Marsden BD, Spencer J et al. 2016. A poised fragment library enables rapid synthetic expansion yielding the first reported inhibitors of PHIP(2), an atypical bromodomain CHEMICAL SCIENCE, 7 (3), pp. 2322-2330. | Show Abstract | Read more

© The Royal Society of Chemistry 2016. Research into the chemical biology of bromodomains has been driven by the development of acetyl-lysine mimetics. The ligands are typically anchored by binding to a highly conserved asparagine residue. Atypical bromodomains, for which the asparagine is mutated, have thus far proven elusive targets, including PHIP(2) whose parent protein, PHIP, has been linked to disease progression in diabetes and cancers. The PHIP(2) binding site contains a threonine in place of asparagine, and solution screening have yielded no convincing hits. We have overcome this hurdle by combining the sensitivity of X-ray crystallography, used as the primary fragment screen, with a strategy for rapid follow-up synthesis using a chemically-poised fragment library, which allows hits to be readily modified by parallel chemistry both peripherally and in the core. Our approach yielded the first reported hit compounds of PHIP(2) with measurable IC 50 values by an AlphaScreen competition assay. The follow-up libraries of four poised fragment hits improved potency into the sub-mM range while showing good ligand efficiency and detailed structural data.

McAllister TE, England KS, Hopkinson RJ, Brennan PE, Kawamura A, Schofield CJ. 2016. Recent Progress in Histone Demethylase Inhibitors. J Med Chem, 59 (4), pp. 1308-1329. | Show Abstract | Read more

There is increasing interest in targeting histone N-methyl-lysine demethylases (KDMs) with small molecules both for the generation of probes for target exploration and for therapeutic purposes. Here we update on previous reviews on the inhibition of the lysine-specific demethylases (LSDs or KDM1s) and JmjC families of N-methyl-lysine demethylases (JmjC KDMs, KDM2-7), focusing on the academic and patent literature from 2014 to date. We also highlight recent biochemical, biological, and structural studies which are relevant to KDM inhibitor development.

Chaikuad A, Lang S, Brennan PE, Temperini C, Fedorov O, Hollander J, Nachane R, Abell C, Müller S, Siegal G, Knapp S. 2016. Structure-Based Identification of Inhibitory Fragments Targeting the p300/CBP-Associated Factor Bromodomain. J Med Chem, 59 (4), pp. 1648-1653. | Show Abstract | Read more

The P300/CBP-associated factor plays a central role in retroviral infection and cancer development, and the C-terminal bromodomain provides an opportunity for selective targeting. Here, we report several new classes of acetyl-lysine mimetic ligands ranging from mM to low micromolar affinity that were identified using fragment screening approaches. The binding modes of the most attractive fragments were determined using high resolution crystal structures providing chemical starting points and structural models for the development of potent and selective PCAF inhibitors.

Bavetsias V, Lanigan RM, Ruda GF, Atrash B, McLaughlin MG, Tumber A, Mok NY, Le Bihan Y-V, Dempster S, Boxall KJ et al. 2016. 8-Substituted Pyrido[3,4-d]pyrimidin-4(3H)-one Derivatives As Potent, Cell Permeable, KDM4 (JMJD2) and KDM5 (JARID1) Histone Lysine Demethylase Inhibitors. J Med Chem, 59 (4), pp. 1388-1409. | Show Abstract | Read more

We report the discovery of N-substituted 4-(pyridin-2-yl)thiazole-2-amine derivatives and their subsequent optimization, guided by structure-based design, to give 8-(1H-pyrazol-3-yl)pyrido[3,4-d]pyrimidin-4(3H)-ones, a series of potent JmjC histone N-methyl lysine demethylase (KDM) inhibitors which bind to Fe(II) in the active site. Substitution from C4 of the pyrazole moiety allows access to the histone peptide substrate binding site; incorporation of a conformationally constrained 4-phenylpiperidine linker gives derivatives such as 54j and 54k which demonstrate equipotent activity versus the KDM4 (JMJD2) and KDM5 (JARID1) subfamily demethylases, selectivity over representative exemplars of the KDM2, KDM3, and KDM6 subfamilies, cellular permeability in the Caco-2 assay, and, for 54k, inhibition of H3K9Me3 and H3K4Me3 demethylation in a cell-based assay.

Brennan PE. 2016. Deciphering the true antiproliferative target of an MK2 activation inhibitor in glioblastoma. Cell Death Dis, 7 (1), pp. e2069. | Read more

Picaud S, Fedorov O, Thanasopoulou A, Leonards K, Jones K, Meier J, Olzscha H, Monteiro O, Martin S, Philpott M et al. 2015. Generation of a Selective Small Molecule Inhibitor of the CBP/p300 Bromodomain for Leukemia Therapy. Cancer Res, 75 (23), pp. 5106-5119. | Show Abstract | Read more

The histone acetyltransferases CBP/p300 are involved in recurrent leukemia-associated chromosomal translocations and are key regulators of cell growth. Therefore, efforts to generate inhibitors of CBP/p300 are of clinical value. We developed a specific and potent acetyl-lysine competitive protein-protein interaction inhibitor, I-CBP112, that targets the CBP/p300 bromodomains. Exposure of human and mouse leukemic cell lines to I-CBP112 resulted in substantially impaired colony formation and induced cellular differentiation without significant cytotoxicity. I-CBP112 significantly reduced the leukemia-initiating potential of MLL-AF9(+) acute myeloid leukemia cells in a dose-dependent manner in vitro and in vivo. Interestingly, I-CBP112 increased the cytotoxic activity of BET bromodomain inhibitor JQ1 as well as doxorubicin. Collectively, we report the development and preclinical evaluation of a novel, potent inhibitor targeting CBP/p300 bromodomains that impairs aberrant self-renewal of leukemic cells. The synergistic effects of I-CBP112 and current standard therapy (doxorubicin) as well as emerging treatment strategies (BET inhibition) provide new opportunities for combinatorial treatment of leukemia and potentially other cancers.

Fedorov O, Castex J, Tallant C, Owen DR, Martin S, Aldeghi M, Monteiro O, Filippakopoulos P, Picaud S, Trzupek JD et al. 2015. Selective targeting of the BRG/PB1 bromodomains impairs embryonic and trophoblast stem cell maintenance. Sci Adv, 1 (10), pp. e1500723. | Show Abstract | Read more

Mammalian SWI/SNF [also called Brg/Brahma-associated factors (BAFs)] are evolutionarily conserved chromatin-remodeling complexes regulating gene transcription programs during development and stem cell differentiation. BAF complexes contain an ATP (adenosine 5'-triphosphate)-driven remodeling enzyme (either BRG1 or BRM) and multiple protein interaction domains including bromodomains, an evolutionary conserved acetyl lysine-dependent protein interaction motif that recruits transcriptional regulators to acetylated chromatin. We report a potent and cell active protein interaction inhibitor, PFI-3, that selectively binds to essential BAF bromodomains. The high specificity of PFI-3 was achieved on the basis of a novel binding mode of a salicylic acid head group that led to the replacement of water molecules typically maintained in other bromodomain inhibitor complexes. We show that exposure of embryonic stem cells to PFI-3 led to deprivation of stemness and deregulated lineage specification. Furthermore, differentiation of trophoblast stem cells in the presence of PFI-3 was markedly enhanced. The data present a key function of BAF bromodomains in stem cell maintenance and differentiation, introducing a novel versatile chemical probe for studies on acetylation-dependent cellular processes controlled by BAF remodeling complexes.

Arrowsmith CH, Audia JE, Austin C, Baell J, Bennett J, Blagg J, Bountra C, Brennan PE, Brown PJ, Bunnage ME et al. 2015. Corrigendum: The promise and peril of chemical probes. Nat Chem Biol, 11 (11), pp. 887. | Read more

Canning P, Ruan Q, Schwerd T, Hrdinka M, Maki JL, Saleh D, Suebsuwong C, Ray S, Brennan PE, Cuny GD et al. 2015. Inflammatory Signaling by NOD-RIPK2 Is Inhibited by Clinically Relevant Type II Kinase Inhibitors. Chem Biol, 22 (9), pp. 1174-1184. | Show Abstract | Read more

RIPK2 mediates pro-inflammatory signaling from the bacterial sensors NOD1 and NOD2, and is an emerging therapeutic target in autoimmune and inflammatory diseases. We observed that cellular RIPK2 can be potently inhibited by type II inhibitors that displace the kinase activation segment, whereas ATP-competitive type I inhibition was only poorly effective. The most potent RIPK2 inhibitors were the US Food and Drug Administration-approved drugs ponatinib and regorafenib. Their mechanism of action was independent of NOD2 interaction and involved loss of downstream kinase activation as evidenced by lack of RIPK2 autophosphorylation. Notably, these molecules also blocked RIPK2 ubiquitination and, consequently, inflammatory nuclear factor κB signaling. In monocytes, the inhibitors selectively blocked NOD-dependent tumor necrosis factor production without affecting lipopolysaccharide-dependent pathways. We also determined the first crystal structure of RIPK2 bound to ponatinib, and identified an allosteric site for inhibitor development. These results highlight the potential for type II inhibitors to treat indications of RIPK2 activation as well as inflammation-associated cancers.

Hammitzsch A, Tallant C, Fedorov O, O'Mahony A, Brennan PE, Hay DA, Martinez FO, Al-Mossawi MH, de Wit J, Vecellio M et al. 2015. CBP30, a selective CBP/p300 bromodomain inhibitor, suppresses human Th17 responses. Proc Natl Acad Sci U S A, 112 (34), pp. 10768-10773. | Show Abstract | Read more

Th17 responses are critical to a variety of human autoimmune diseases, and therapeutic targeting with monoclonal antibodies against IL-17 and IL-23 has shown considerable promise. Here, we report data to support selective bromodomain blockade of the transcriptional coactivators CBP (CREB binding protein) and p300 as an alternative approach to inhibit human Th17 responses. We show that CBP30 has marked molecular specificity for the bromodomains of CBP and p300, compared with 43 other bromodomains. In unbiased cellular testing on a diverse panel of cultured primary human cells, CBP30 reduced immune cell production of IL-17A and other proinflammatory cytokines. CBP30 also inhibited IL-17A secretion by Th17 cells from healthy donors and patients with ankylosing spondylitis and psoriatic arthritis. Transcriptional profiling of human T cells after CBP30 treatment showed a much more restricted effect on gene expression than that observed with the pan-BET (bromo and extraterminal domain protein family) bromodomain inhibitor JQ1. This selective targeting of the CBP/p300 bromodomain by CBP30 will potentially lead to fewer side effects than with the broadly acting epigenetic inhibitors currently in clinical trials.

Arrowsmith CH, Audia JE, Austin C, Baell J, Bennett J, Blagg J, Bountra C, Brennan PE, Brown PJ, Bunnage ME et al. 2015. The promise and peril of chemical probes. Nat Chem Biol, 11 (8), pp. 536-541. | Show Abstract | Read more

© 2015 Nature America, Inc. All rights reserved. Chemical probes are powerful reagents with increasing impacts on biomedical research. However, probes of poor quality or that are used incorrectly generate misleading results. To help address these shortcomings, we will create a community-driven wiki resource to improve quality and convey current best practice.

Cited:

22

Scopus

Hay DA, Rogers CM, Fedorov O, Tallant C, Martin S, Monteiro OP, Mueller S, Knapp S, Schofield CJ, Brennan PE. 2015. Design and synthesis of potent and selective inhibitors of BRD7 and BRD9 bromodomains MEDCHEMCOMM, 6 (7), pp. 1381-1386. | Show Abstract | Read more

© The Royal Society of Chemistry. Emerging evidence suggests bromodomain-containing proteins 7 and 9 (BRD7 and BRD9) have roles in the regulation of human transcription and disease including cancer. We describe potent and selective inhibitors of the BRD7 and BRD9 bromodomains intended for use as tools to elucidate the biological roles of BRD7 and BRD9 in healthy and diseased cells.

Clark PGK, Vieira LCC, Tallant C, Fedorov O, Singleton DC, Rogers CM, Monteiro OP, Bennett JM, Baronio R, Müller S et al. 2015. LP99: Discovery and Synthesis of the First Selective BRD7/9 Bromodomain Inhibitor. Angew Chem Weinheim Bergstr Ger, 127 (21), pp. 6315-6319. | Show Abstract | Read more

The bromodomain-containing proteins BRD9 and BRD7 are part of the human SWI/SNF chromatin-remodeling complexes BAF and PBAF. To date, no selective inhibitor for BRD7/9 has been reported despite its potential value as a biological tool or as a lead for future therapeutics. The quinolone-fused lactam LP99 is now reported as the first potent and selective inhibitor of the BRD7 and BRD9 bromodomains. Development of LP99 from a fragment hit was expedited through balancing structure-based inhibitor design and biophysical characterization against tractable chemical synthesis: Complexity-building nitro-Mannich/lactamization cascade processes allowed for early structure-activity relationship studies whereas an enantioselective organocatalytic nitro-Mannich reaction enabled the synthesis of the lead scaffold in enantioenriched form and on scale. This epigenetic probe was shown to inhibit the association of BRD7 and BRD9 to acetylated histones in vitro and in cells. Moreover, LP99 was used to demonstrate that BRD7/9 plays a role in regulating pro-inflammatory cytokine secretion.

Clark PGK, Vieira LCC, Tallant C, Fedorov O, Singleton DC, Rogers CM, Monteiro OP, Bennett JM, Baronio R, Müller S et al. 2015. LP99: Discovery and Synthesis of the First Selective BRD7/9 Bromodomain Inhibitor. Angew Chem Int Ed Engl, 54 (21), pp. 6217-6221. | Show Abstract | Read more

The bromodomain-containing proteins BRD9 and BRD7 are part of the human SWI/SNF chromatin-remodeling complexes BAF and PBAF. To date, no selective inhibitor for BRD7/9 has been reported despite its potential value as a biological tool or as a lead for future therapeutics. The quinolone-fused lactam LP99 is now reported as the first potent and selective inhibitor of the BRD7 and BRD9 bromodomains. Development of LP99 from a fragment hit was expedited through balancing structure-based inhibitor design and biophysical characterization against tractable chemical synthesis: Complexity-building nitro-Mannich/lactamization cascade processes allowed for early structure-activity relationship studies whereas an enantioselective organocatalytic nitro-Mannich reaction enabled the synthesis of the lead scaffold in enantioenriched form and on scale. This epigenetic probe was shown to inhibit the association of BRD7 and BRD9 to acetylated histones in vitro and in cells. Moreover, LP99 was used to demonstrate that BRD7/9 plays a role in regulating pro-inflammatory cytokine secretion.

Bennett J, Fedorov O, Tallant C, Monteiro O, Meier J, Gamble V, Savitsky P, Nunez-Alonso GA, Haendler B, Rogers C et al. 2016. Discovery of a Chemical Tool Inhibitor Targeting the Bromodomains of TRIM24 and BRPF. J Med Chem, 59 (4), pp. 1642-1647. | Show Abstract | Read more

TRIM24 is a transcriptional regulator as well as an E3 ubiquitin ligase. It is overexpressed in diverse tumors, and high expression levels have been linked to poor prognosis in breast cancer patients. TRIM24 contains a PHD/bromodomain offering the opportunity to develop protein interaction inhibitors that target this protein interaction module. Here we identified potent acetyl-lysine mimetic benzimidazolones TRIM24 bromodomain inhibitors. The best compound of this series is a selective BRPF1B/TRIM24 dual inhibitor that bound with a KD of 137 and 222 nM, respectively, but exerted good selectivity over other bromodomains. Cellular activity of the inhibitor was demonstrated using FRAP assays as well as cell viability data.

Dong YY, Pike ACW, Mackenzie A, McClenaghan C, Aryal P, Dong L, Quigley A, Grieben M, Goubin S, Mukhopadhyay S et al. 2015. K2P channel gating mechanisms revealed by structures of TREK-2 and a complex with Prozac. Science, 347 (6227), pp. 1256-1259. | Show Abstract | Read more

TREK-2 (KCNK10/K2P10), a two-pore domain potassium (K2P) channel, is gated by multiple stimuli such as stretch, fatty acids, and pH and by several drugs. However, the mechanisms that control channel gating are unclear. Here we present crystal structures of the human TREK-2 channel (up to 3.4 angstrom resolution) in two conformations and in complex with norfluoxetine, the active metabolite of fluoxetine (Prozac) and a state-dependent blocker of TREK channels. Norfluoxetine binds within intramembrane fenestrations found in only one of these two conformations. Channel activation by arachidonic acid and mechanical stretch involves conversion between these states through movement of the pore-lining helices. These results provide an explanation for TREK channel mechanosensitivity, regulation by diverse stimuli, and possible off-target effects of the serotonin reuptake inhibitor Prozac.

Thinnes CC, Tumber A, Yapp C, Scozzafava G, Yeh T, Chan MC, Tran TA, Hsu K, Tarhonskaya H, Walport LJ et al. 2015. Betti reaction enables efficient synthesis of 8-hydroxyquinoline inhibitors of 2-oxoglutarate oxygenases. Chem Commun (Camb), 51 (84), pp. 15458-15461. | Show Abstract | Read more

There is interest in developing potent, selective, and cell-permeable inhibitors of human ferrous iron and 2-oxoglutarate (2OG) oxygenases for use in functional and target validation studies. The 3-component Betti reaction enables efficient one-step C-7 functionalisation of modified 8-hydroxyquinolines (8HQs) to produce cell-active inhibitors of KDM4 histone demethylases and other 2OG oxygenases; the work exemplifies how a template-based metallo-enzyme inhibitor approach can be used to give biologically active compounds.

England KS, Tumber A, Krojer T, Scozzafava G, Ng SS, Daniel M, Szykowska A, Che K, von Delft F, Burgess-Brown NA et al. 2014. Optimisation of a triazolopyridine based histone demethylase inhibitor yields a potent and selective KDM2A (FBXL11) inhibitor. Medchemcomm, 5 (12), pp. 1879-1886. | Show Abstract | Read more

A potent inhibitor of the JmjC histone lysine demethylase KDM2A (compound 35, pIC50 7.2) with excellent selectivity over representatives from other KDM subfamilies has been developed; the discovery that a triazolopyridine compound binds to the active site of JmjC KDMs was followed by optimisation of the triazole substituent for KDM2A inhibition and selectivity.

Storer RI, Brennan PE, Brown AD, Bungay PJ, Conlon KM, Corbett MS, DePianta RP, Fish PV, Heifetz A, Ho DKH et al. 2014. Multiparameter optimization in CNS drug discovery: design of pyrimido[4,5-d]azepines as potent 5-hydroxytryptamine 2C (5-HT₂C) receptor agonists with exquisite functional selectivity over 5-HT₂A and 5-HT₂B receptors. J Med Chem, 57 (12), pp. 5258-5269. | Show Abstract | Read more

A series of 4-substituted pyrimido[4,5-d]azepines that are potent, selective 5-HT2C receptor partial agonists is described. A rational medicinal chemistry design strategy to deliver CNS penetration coupled with SAR-based optimization of selectivity and agonist potency provided compounds with the desired balance of preclinical properties. Lead compounds 17 (PF-4479745) and 18 (PF-4522654) displayed robust pharmacology in a preclinical canine model of stress urinary incontinence (SUI) and no measurable functional agonism at the key selectivity targets 5-HT2A and 5-HT2B in relevant tissue-based assay systems. Utilizing recent advances in the structural biology of GPCRs, homology modeling has been carried out to rationalize binding and agonist efficacy of these compounds.

Hay DA, Fedorov O, Martin S, Singleton DC, Tallant C, Wells C, Picaud S, Philpott M, Monteiro OP, Rogers CM et al. 2014. Discovery and optimization of small-molecule ligands for the CBP/p300 bromodomains. J Am Chem Soc, 136 (26), pp. 9308-9319. | Show Abstract | Read more

Small-molecule inhibitors that target bromodomains outside of the bromodomain and extra-terminal (BET) sub-family are lacking. Here, we describe highly potent and selective ligands for the bromodomain module of the human lysine acetyl transferase CBP/p300, developed from a series of 5-isoxazolyl-benzimidazoles. Our starting point was a fragment hit, which was optimized into a more potent and selective lead using parallel synthesis employing Suzuki couplings, benzimidazole-forming reactions, and reductive aminations. The selectivity of the lead compound against other bromodomain family members was investigated using a thermal stability assay, which revealed some inhibition of the structurally related BET family members. To address the BET selectivity issue, X-ray crystal structures of the lead compound bound to the CREB binding protein (CBP) and the first bromodomain of BRD4 (BRD4(1)) were used to guide the design of more selective compounds. The crystal structures obtained revealed two distinct binding modes. By varying the aryl substitution pattern and developing conformationally constrained analogues, selectivity for CBP over BRD4(1) was increased. The optimized compound is highly potent (Kd = 21 nM) and selective, displaying 40-fold selectivity over BRD4(1). Cellular activity was demonstrated using fluorescence recovery after photo-bleaching (FRAP) and a p53 reporter assay. The optimized compounds are cell-active and have nanomolar affinity for CBP/p300; therefore, they should be useful in studies investigating the biological roles of CBP and p300 and to validate the CBP and p300 bromodomains as therapeutic targets.

Rooney TPC, Filippakopoulos P, Fedorov O, Picaud S, Cortopassi WA, Hay DA, Martin S, Tumber A, Rogers CM, Philpott M et al. 2014. A series of potent CREBBP bromodomain ligands reveals an induced-fit pocket stabilized by a cation-π interaction. Angew Chem Int Ed Engl, 53 (24), pp. 6126-6130. | Show Abstract | Read more

The benzoxazinone and dihydroquinoxalinone fragments were employed as novel acetyl lysine mimics in the development of CREBBP bromodomain ligands. While the benzoxazinone series showed low affinity for the CREBBP bromodomain, expansion of the dihydroquinoxalinone series resulted in the first potent inhibitors of a bromodomain outside the BET family. Structural and computational studies reveal that an internal hydrogen bond stabilizes the protein-bound conformation of the dihydroquinoxalinone series. The side chain of this series binds in an induced-fit pocket forming a cation-π interaction with R1173 of CREBBP. The most potent compound inhibits binding of CREBBP to chromatin in U2OS cells.

Guetzoyan L, Ingham RJ, Nikbin N, Rossignol J, Wolling M, Baumert M, Burgess-Brown NA, Strain-Damerell CM, Shrestha L, Brennan PE et al. 2014. Machine-assisted synthesis of modulators of the histone reader BRD9 using flow methods of chemistry and frontal affinity chromatography MEDCHEMCOMM, 5 (4), pp. 540-546. | Show Abstract | Read more

A combination of conventional organic synthesis, remotely monitored flow synthesis and bioassay platforms, were used for the evaluation of novel inhibitors targeting bromodomains outside the well-studied bromodomain and extra terminal (BET) family, here exemplified by activity measurements on the bromodomain of BRD9 protein, a component of some tissue-specific SWi/SNF chromatin remodelling complexes. The Frontal Affinity Chromatography combined with Mass Spectrometry (FAC-MS) method proved to be reliable and results correlated well with an independent thermal shift assay. © 2014 the Partner Organisations.

Yue WW, Froese DS, Brennan PE. 2014. The role of protein structural analysis in the next generation sequencing era Topics in Current Chemistry, 336 pp. 67-98. | Show Abstract | Read more

Proteins are macromolecules that serve a cell's myriad processes and functions in all living organisms via dynamic interactions with other proteins, small molecules and cellular components. Genetic variations in the protein-encoding regions of the human genome account for > 85% of all known Mendelian diseases, and play an influential role in shaping complex polygenic diseases. Proteins also serve as the predominant target class for the design of small molecule drugs to modulate their activity. Knowledge of the shape and form of proteins, by means of their three-dimensional structures, is therefore instrumental to understanding their roles in disease and their potentials for drug development. In this chapter we outline, with the wide readership of non-structural biologists in mind, the various experimental and computational methods available for protein structure determination. We summarize how the wealth of structure information, contributed to a large extent by the technological advances in structure determination to date, serves as a useful tool to decipher the molecular basis of genetic variations for disease characterization and diagnosis, particularly in the emerging era of genomic medicine, and becomes an integral component in the modern day approach towards rational drug development. © Springer-Verlag Berlin Heidelberg 2012.

Fedorov O, Lingard H, Wells C, Monteiro OP, Picaud S, Keates T, Yapp C, Philpott M, Martin SJ, Felletar I et al. 2014. [1,2,4]triazolo[4,3-a]phthalazines: inhibitors of diverse bromodomains. J Med Chem, 57 (2), pp. 462-476. | Show Abstract | Read more

Bromodomains are gaining increasing interest as drug targets. Commercially sourced and de novo synthesized substituted [1,2,4]triazolo[4,3-a]phthalazines are potent inhibitors of both the BET bromodomains such as BRD4 as well as bromodomains outside the BET family such as BRD9, CECR2, and CREBBP. This new series of compounds is the first example of submicromolar inhibitors of bromodomains outside the BET subfamily. Representative compounds are active in cells exhibiting potent cellular inhibition activity in a FRAP model of CREBBP and chromatin association. The compounds described are valuable starting points for discovery of selective bromodomain inhibitors and inhibitors with mixed bromodomain pharmacology.

Morley AD, Pugliese A, Birchall K, Bower J, Brennan P, Brown N, Chapman T, Drysdale M, Gilbert IH, Hoelder S et al. 2013. Fragment-based hit identification: thinking in 3D. Drug Discov Today, 18 (23-24), pp. 1221-1227. | Show Abstract | Read more

The identification of high-quality hits during the early phases of drug discovery is essential if projects are to have a realistic chance of progressing into clinical development and delivering marketed drugs. As the pharmaceutical industry goes through unprecedented change, there are increasing opportunities to collaborate via pre-competitive networks to marshal multifunctional resources and knowledge to drive impactful, innovative science. The 3D Fragment Consortium is developing fragment-screening libraries with enhanced 3D characteristics and evaluating their effect on the quality of fragment-based hit identification (FBHI) projects.

Picaud S, Wells C, Felletar I, Brotherton D, Martin S, Savitsky P, Diez-Dacal B, Philpott M, Bountra C, Lingard H et al. 2013. RVX-208, an inhibitor of BET transcriptional regulators with selectivity for the second bromodomain. Proc Natl Acad Sci U S A, 110 (49), pp. 19754-19759. | Show Abstract | Read more

Bromodomains have emerged as attractive candidates for the development of inhibitors targeting gene transcription. Inhibitors of the bromo and extraterminal (BET) family recently showed promising activity in diverse disease models. However, the pleiotropic nature of BET proteins regulating tissue-specific transcription has raised safety concerns and suggested that attempts should be made for domain-specific targeting. Here, we report that RVX-208, a compound currently in phase II clinical trials, is a BET bromodomain inhibitor specific for second bromodomains (BD2s). Cocrystal structures revealed binding modes of RVX-208 and its synthetic precursor, and fluorescent recovery after photobleaching demonstrated that RVX-208 displaces BET proteins from chromatin. However, gene-expression data showed that BD2 inhibition only modestly affects BET-dependent gene transcription. Our data demonstrate the feasibility of specific targeting within the BET family resulting in different transcriptional outcomes and highlight the importance of BD1 in transcriptional regulation.

Hopkinson RJ, Tumber A, Yapp C, Chowdhury R, Aik W, Che KH, Li XS, Kristensen JBL, King ONF, Chan MC et al. 2013. 5-Carboxy-8-hydroxyquinoline is a Broad Spectrum 2-Oxoglutarate Oxygenase Inhibitor which Causes Iron Translocation. Chem Sci, 4 (8), pp. 3110-3117. | Show Abstract | Read more

2-Oxoglutarate and iron dependent oxygenases are therapeutic targets for human diseases. Using a representative 2OG oxygenase panel, we compare the inhibitory activities of 5-carboxy-8-hydroxyquinoline (IOX1) and 4-carboxy-8-hydroxyquinoline (4C8HQ) with that of two other commonly used 2OG oxygenase inhibitors, N-oxalylglycine (NOG) and 2,4-pyridinedicarboxylic acid (2,4-PDCA). The results reveal that IOX1 has a broad spectrum of activity, as demonstrated by the inhibition of transcription factor hydroxylases, representatives of all 2OG dependent histone demethylase subfamilies, nucleic acid demethylases and γ-butyrobetaine hydroxylase. Cellular assays show that, unlike NOG and 2,4-PDCA, IOX1 is active against both cytosolic and nuclear 2OG oxygenases without ester derivatisation. Unexpectedly, crystallographic studies on these oxygenases demonstrate that IOX1, but not 4C8HQ, can cause translocation of the active site metal, revealing a rare example of protein ligand-induced metal movement.

Picaud S, Da Costa D, Thanasopoulou A, Filippakopoulos P, Fish PV, Philpott M, Fedorov O, Brennan P, Bunnage ME, Owen DR et al. 2013. PFI-1, a highly selective protein interaction inhibitor, targeting BET Bromodomains. Cancer Res, 73 (11), pp. 3336-3346. | Show Abstract | Read more

Bromo and extra terminal (BET) proteins (BRD2, BRD3, BRD4, and BRDT) are transcriptional regulators required for efficient expression of several growth promoting and antiapoptotic genes as well as for cell-cycle progression. BET proteins are recruited on transcriptionally active chromatin via their two N-terminal bromodomains (BRD), a protein interaction module that specifically recognizes acetylated lysine residues in histones H3 and H4. Inhibition of the BET-histone interaction results in transcriptional downregulation of a number of oncogenes, providing a novel pharmacologic strategy for the treatment of cancer. Here, we present a potent and highly selective dihydroquinazoline-2-one inhibitor, PFI-1, which efficiently blocks the interaction of BET BRDs with acetylated histone tails. Cocrystal structures showed that PFI-1 acts as an acetyl-lysine (Kac) mimetic inhibitor efficiently occupying the Kac binding site in BRD4 and BRD2. PFI-1 has antiproliferative effects on leukemic cell lines and efficiently abrogates their clonogenic growth. Exposure of sensitive cell lines with PFI-1 results in G1 cell-cycle arrest, downregulation of MYC expression, as well as induction of apoptosis and induces differentiation of primary leukemic blasts. Intriguingly, cells exposed to PFI-1 showed significant downregulation of Aurora B kinase, thus attenuating phosphorylation of the Aurora substrate H3S10, providing an alternative strategy for the specific inhibition of this well-established oncology target.

Hewings DS, Fedorov O, Filippakopoulos P, Martin S, Picaud S, Tumber A, Wells C, Olcina MM, Freeman K, Gill A et al. 2013. Optimization of 3,5-dimethylisoxazole derivatives as potent bromodomain ligands. J Med Chem, 56 (8), pp. 3217-3227. | Show Abstract | Read more

The bromodomain protein module, which binds to acetylated lysine, is emerging as an important epigenetic therapeutic target. We report the structure-guided optimization of 3,5-dimethylisoxazole derivatives to develop potent inhibitors of the BET (bromodomain and extra terminal domain) bromodomain family with good ligand efficiency. X-ray crystal structures of the most potent compounds reveal key interactions required for high affinity at BRD4(1). Cellular studies demonstrate that the phenol and acetate derivatives of the lead compounds showed strong antiproliferative effects on MV4;11 acute myeloid leukemia cells, as shown for other BET bromodomain inhibitors and genetic BRD4 knockdown, whereas the reported compounds showed no general cytotoxicity in other cancer cell lines tested.

Hay D, Fedorov O, Filippakopoulos P, Martin S, Philpott M, Picaud S, Hewings DS, Uttakar S, Heightman TD, Conway SJ et al. 2013. The design and synthesis of 5- and 6-isoxazolylbenzimidazoles as selective inhibitors of the BET bromodomains. Medchemcomm, 4 (1), pp. 140-144. | Show Abstract | Read more

Simple 1-substituted 5- and 6-isoxazolyl-benzimidazoles have been shown to be potent inhibitors of the BET bromodomains with selectivity over the related bromodomain of CBP. The reported inhibitors were prepared from simple starting materials in two steps followed by separation of the regioisomers or regioselectively in three steps.

Fish PV, Filippakopoulos P, Bish G, Brennan PE, Bunnage ME, Cook AS, Federov O, Gerstenberger BS, Jones H, Knapp S et al. 2012. Identification of a chemical probe for bromo and extra C-terminal bromodomain inhibition through optimization of a fragment-derived hit. J Med Chem, 55 (22), pp. 9831-9837. | Show Abstract | Read more

The posttranslational modification of chromatin through acetylation at selected histone lysine residues is governed by histone acetyltransferases (HATs) and histone deacetylases (HDACs). The significance of this subset of the epigenetic code is interrogated and interpreted by an acetyllysine-specific protein-protein interaction with bromodomain reader modules. Selective inhibition of the bromo and extra C-terminal domain (BET) family of bromodomains with a small molecule is feasible, and this may represent an opportunity for disease intervention through the recently disclosed antiproliferative and anti-inflammatory properties of such inhibitors. Herein, we describe the discovery and structure-activity relationship (SAR) of a novel, small-molecule chemical probe for BET family inhibition that was identified through the application of structure-based fragment assessment and optimization techniques. This has yielded a potent, selective compound with cell-based activity (PFI-1) that may further add to the understanding of BET family function within the bromodomains.

Hewings DS, Rooney TPC, Jennings LE, Hay DA, Schofield CJ, Brennan PE, Knapp S, Conway SJ. 2012. Progress in the development and application of small molecule inhibitors of bromodomain-acetyl-lysine interactions. J Med Chem, 55 (22), pp. 9393-9413. | Show Abstract | Read more

Bromodomains, protein modules that recognize and bind to acetylated lysine, are emerging as important components of cellular machinery. These acetyl-lysine (KAc) "reader" domains are part of the write-read-erase concept that has been linked with the transfer of epigenetic information. By reading KAc marks on histones, bromodomains mediate protein-protein interactions between a diverse array of partners. There has been intense activity in developing potent and selective small molecule probes that disrupt the interaction between a given bromodomain and KAc. Rapid success has been achieved with the BET family of bromodomains, and a number of potent and selective probes have been reported. These compounds have enabled linking of the BET bromodomains with diseases, including cancer and inflammation, suggesting that bromodomains are druggable targets. Herein, we review the biology of the bromodomains and discuss the SAR for the existing small molecule probes. The biology that has been enabled by these compounds is summarized.

Rose NR, Woon ECY, Tumber A, Walport LJ, Chowdhury R, Li XS, King ONF, Lejeune C, Ng SS, Krojer T et al. 2012. Plant growth regulator daminozide is a selective inhibitor of human KDM2/7 histone demethylases. J Med Chem, 55 (14), pp. 6639-6643. | Show Abstract | Read more

The JmjC oxygenases catalyze the N-demethylation of N(ε)-methyl lysine residues in histones and are current therapeutic targets. A set of human 2-oxoglutarate analogues were screened using a unified assay platform for JmjC demethylases and related oxygenases. Results led to the finding that daminozide (N-(dimethylamino)succinamic acid, 160 Da), a plant growth regulator, selectively inhibits the KDM2/7 JmjC subfamily. Kinetic and crystallographic studies reveal that daminozide chelates the active site metal via its hydrazide carbonyl and dimethylamino groups.

Yue WW, Froese DS, Brennan PE. 2014. The role of protein structural analysis in the next generation sequencing era. Top Curr Chem, 336 pp. 67-98. | Show Abstract | Read more

Proteins are macromolecules that serve a cell's myriad processes and functions in all living organisms via dynamic interactions with other proteins, small molecules and cellular components. Genetic variations in the protein-encoding regions of the human genome account for >85% of all known Mendelian diseases, and play an influential role in shaping complex polygenic diseases. Proteins also serve as the predominant target class for the design of small molecule drugs to modulate their activity. Knowledge of the shape and form of proteins, by means of their three-dimensional structures, is therefore instrumental to understanding their roles in disease and their potentials for drug development. In this chapter we outline, with the wide readership of non-structural biologists in mind, the various experimental and computational methods available for protein structure determination. We summarize how the wealth of structure information, contributed to a large extent by the technological advances in structure determination to date, serves as a useful tool to decipher the molecular basis of genetic variations for disease characterization and diagnosis, particularly in the emerging era of genomic medicine, and becomes an integral component in the modern day approach towards rational drug development.

Brennan P, Filippakopoulos P, Knapp S. 2012. The therapeutic potential of acetyl-lysine and methyl-lysine effector domains Drug Discovery Today: Therapeutic Strategies, 9 (2-3), pp. e101-e110. | Show Abstract | Read more

Epigenetic reader domains are protein interaction modules that selectively recognize common post-translational modification on histones and other nuclear proteins such as ε-N-acetylated lysine or methyllysine/arginine residues. Interactions mediated by these effector domains result in the recruitment of gene specific transcriptional regulators. This review focusses on reader domains that recognize acetylated and methylated lysine and arginine residues. Bromodomains selectively recognize acetylated lysines residues and inhibitors have recently emerged as promising lead compounds for the treatment of cancer and inflammatory diseases, acting by specifically repressing expression of oncogenes and pro-inflammatory cytokines. Initial inhibitors have also been reported for methyllysine binding domains. Here we review recent development of this emerging target area. © 2012 Elsevier Ltd. All rights reserved.

Andrews MD, Fish PV, Blagg J, Brabham TK, Brennan PE, Bridgeland A, Brown AD, Bungay PJ, Conlon KM, Edmunds NJ et al. 2011. Pyrimido[4,5-d]azepines as potent and selective 5-HT2C receptor agonists: Design, synthesis, and evaluation of PF-3246799 as a treatment for urinary incontinence Bioorganic & Medicinal Chemistry Letters, 21 (9), pp. 2715-2720. | Read more

Ho DKH, Chan L, Hooper A, Brennan PE. 2011. A general and mild two-step procedure for the synthesis of aryl and heteroaryl sulfonamides from the corresponding iodides Tetrahedron Letters, 52 (7), pp. 820-823. | Read more

Ley SV, Tackett MN, Maddess ML, Anderson JC, Brennan PE, Cappi MW, Heer JP, Helgen C, Kori M, Kouklovsky C et al. 2009. Total synthesis of rapamycin. Chemistry, 15 (12), pp. 2874-2914. | Show Abstract | Read more

For over 30 years, rapamycin has generated a sustained and intense interest from the scientific community as a result of its exceptional pharmacological properties and challenging structural features. In addition to its well known therapeutic value as a potent immunosuppressive agent, rapamycin and its derivatives have recently gained prominence for the treatment of a wide variety of other human malignancies. Herein we disclose full details of our extensive investigation into the synthesis of rapamycin that culminated in a new and convergent preparation featuring a macro-etherification/catechol-templating strategy for construction of the macrocyclic core of this natural product.

Brennan PE, Whitlock GA, Ho DKH, Conlon K, McMurray G. 2009. Discovery of a novel azepine series of potent and selective 5-HT2C agonists as potential treatments for urinary incontinence Bioorganic & Medicinal Chemistry Letters, 19 (17), pp. 4999-5003. | Read more

Whitlock GA, Brennan PE, Roberts LR, Stobie A. 2009. Potent and selective α1A adrenoceptor partial agonists—Novel imidazole frameworks Bioorganic & Medicinal Chemistry Letters, 19 (11), pp. 3118-3121. | Read more

Maddess ML, Tackett MN, Watanabe H, Brennan PE, Spilling CD, Scott JS, Osborn DP, Ley SV. 2007. Total Synthesis of Rapamycin Angewandte Chemie International Edition, 46 (4), pp. 591-597. | Read more

Smith MD, Stepan AF, Ramarao C, Brennan PE, Ley SV. 2003. Palladium-containing perovskites: recoverable and reuseable catalysts for Suzuki couplings. Chem Commun (Camb), (21), pp. 2652-2653. | Show Abstract | Read more

Palladium-containing perovskites (LaFe0.57Co0.38Pd0.05O3) have been exploited as recoverable and reuseable catalysts in Suzuki coupling reactions; residual levels of Pd after removal of the catalyst by filtration are low (2 ppm) despite evidence that the reaction is occurring via a homogeneous process.

MacCoss RN, Brennan PE, Ley SV. 2003. Synthesis of carbohydrate derivatives using solid-phase work-up and scavenging techniques. Org Biomol Chem, 1 (12), pp. 2029-2031. | Show Abstract | Read more

Methods to allow the clean preparation of oligosaccharides were investigated using techniques that do not require conventional column chromatography or an aqueous work-up. The route was designed to provide rapid access to oligosaccharides and is suitable for automation and parallel library formation. The research has focused on the glycosidations of a range of glycosyl acceptors with various selenophenyl glycosyl donors using iodine as an activator in the presence of DTBMP, a hindered organic base. Hydroxyl-containing contaminants were removed by scavenging with polymer-supported tosyl chloride.

Gerken PA, Wolstenhulme JR, Tumber A, Hatch SB, Zhang Y, Müller S, Chandler SA, Mair B, Li F, Nijman SMB et al. Discovery of a Highly Selective Cell-Active Inhibitor of the Histone Lysine Demethylases KDM2/7 Angewandte Chemie, | Read more

Canning P, Ruan Q, Schwerd T, Hrdinka M, Maki JL, Saleh D, Suebsuwong C, Ray S, Brennan PE, Cuny GD et al. 2015. Inflammatory Signaling by NOD-RIPK2 Is Inhibited by Clinically Relevant Type II Kinase Inhibitors. Chem Biol, 22 (9), pp. 1174-1184. | Show Abstract | Read more

RIPK2 mediates pro-inflammatory signaling from the bacterial sensors NOD1 and NOD2, and is an emerging therapeutic target in autoimmune and inflammatory diseases. We observed that cellular RIPK2 can be potently inhibited by type II inhibitors that displace the kinase activation segment, whereas ATP-competitive type I inhibition was only poorly effective. The most potent RIPK2 inhibitors were the US Food and Drug Administration-approved drugs ponatinib and regorafenib. Their mechanism of action was independent of NOD2 interaction and involved loss of downstream kinase activation as evidenced by lack of RIPK2 autophosphorylation. Notably, these molecules also blocked RIPK2 ubiquitination and, consequently, inflammatory nuclear factor κB signaling. In monocytes, the inhibitors selectively blocked NOD-dependent tumor necrosis factor production without affecting lipopolysaccharide-dependent pathways. We also determined the first crystal structure of RIPK2 bound to ponatinib, and identified an allosteric site for inhibitor development. These results highlight the potential for type II inhibitors to treat indications of RIPK2 activation as well as inflammation-associated cancers.

Hammitzsch A, Tallant C, Fedorov O, O'Mahony A, Brennan PE, Hay DA, Martinez FO, Al-Mossawi MH, de Wit J, Vecellio M et al. 2015. CBP30, a selective CBP/p300 bromodomain inhibitor, suppresses human Th17 responses. Proc Natl Acad Sci U S A, 112 (34), pp. 10768-10773. | Show Abstract | Read more

Th17 responses are critical to a variety of human autoimmune diseases, and therapeutic targeting with monoclonal antibodies against IL-17 and IL-23 has shown considerable promise. Here, we report data to support selective bromodomain blockade of the transcriptional coactivators CBP (CREB binding protein) and p300 as an alternative approach to inhibit human Th17 responses. We show that CBP30 has marked molecular specificity for the bromodomains of CBP and p300, compared with 43 other bromodomains. In unbiased cellular testing on a diverse panel of cultured primary human cells, CBP30 reduced immune cell production of IL-17A and other proinflammatory cytokines. CBP30 also inhibited IL-17A secretion by Th17 cells from healthy donors and patients with ankylosing spondylitis and psoriatic arthritis. Transcriptional profiling of human T cells after CBP30 treatment showed a much more restricted effect on gene expression than that observed with the pan-BET (bromo and extraterminal domain protein family) bromodomain inhibitor JQ1. This selective targeting of the CBP/p300 bromodomain by CBP30 will potentially lead to fewer side effects than with the broadly acting epigenetic inhibitors currently in clinical trials.

Arrowsmith CH, Audia JE, Austin C, Baell J, Bennett J, Blagg J, Bountra C, Brennan PE, Brown PJ, Bunnage ME et al. 2015. The promise and peril of chemical probes. Nat Chem Biol, 11 (8), pp. 536-541. | Show Abstract | Read more

© 2015 Nature America, Inc. All rights reserved. Chemical probes are powerful reagents with increasing impacts on biomedical research. However, probes of poor quality or that are used incorrectly generate misleading results. To help address these shortcomings, we will create a community-driven wiki resource to improve quality and convey current best practice.

Cited:

22

Scopus

Hay DA, Rogers CM, Fedorov O, Tallant C, Martin S, Monteiro OP, Mueller S, Knapp S, Schofield CJ, Brennan PE. 2015. Design and synthesis of potent and selective inhibitors of BRD7 and BRD9 bromodomains MEDCHEMCOMM, 6 (7), pp. 1381-1386. | Show Abstract | Read more

© The Royal Society of Chemistry. Emerging evidence suggests bromodomain-containing proteins 7 and 9 (BRD7 and BRD9) have roles in the regulation of human transcription and disease including cancer. We describe potent and selective inhibitors of the BRD7 and BRD9 bromodomains intended for use as tools to elucidate the biological roles of BRD7 and BRD9 in healthy and diseased cells.

Clark PGK, Vieira LCC, Tallant C, Fedorov O, Singleton DC, Rogers CM, Monteiro OP, Bennett JM, Baronio R, Müller S et al. 2015. LP99: Discovery and Synthesis of the First Selective BRD7/9 Bromodomain Inhibitor. Angew Chem Int Ed Engl, 54 (21), pp. 6217-6221. | Show Abstract | Read more

The bromodomain-containing proteins BRD9 and BRD7 are part of the human SWI/SNF chromatin-remodeling complexes BAF and PBAF. To date, no selective inhibitor for BRD7/9 has been reported despite its potential value as a biological tool or as a lead for future therapeutics. The quinolone-fused lactam LP99 is now reported as the first potent and selective inhibitor of the BRD7 and BRD9 bromodomains. Development of LP99 from a fragment hit was expedited through balancing structure-based inhibitor design and biophysical characterization against tractable chemical synthesis: Complexity-building nitro-Mannich/lactamization cascade processes allowed for early structure-activity relationship studies whereas an enantioselective organocatalytic nitro-Mannich reaction enabled the synthesis of the lead scaffold in enantioenriched form and on scale. This epigenetic probe was shown to inhibit the association of BRD7 and BRD9 to acetylated histones in vitro and in cells. Moreover, LP99 was used to demonstrate that BRD7/9 plays a role in regulating pro-inflammatory cytokine secretion.

Bennett J, Fedorov O, Tallant C, Monteiro O, Meier J, Gamble V, Savitsky P, Nunez-Alonso GA, Haendler B, Rogers C et al. 2016. Discovery of a Chemical Tool Inhibitor Targeting the Bromodomains of TRIM24 and BRPF. J Med Chem, 59 (4), pp. 1642-1647. | Show Abstract | Read more

TRIM24 is a transcriptional regulator as well as an E3 ubiquitin ligase. It is overexpressed in diverse tumors, and high expression levels have been linked to poor prognosis in breast cancer patients. TRIM24 contains a PHD/bromodomain offering the opportunity to develop protein interaction inhibitors that target this protein interaction module. Here we identified potent acetyl-lysine mimetic benzimidazolones TRIM24 bromodomain inhibitors. The best compound of this series is a selective BRPF1B/TRIM24 dual inhibitor that bound with a KD of 137 and 222 nM, respectively, but exerted good selectivity over other bromodomains. Cellular activity of the inhibitor was demonstrated using FRAP assays as well as cell viability data.

Dong YY, Pike ACW, Mackenzie A, McClenaghan C, Aryal P, Dong L, Quigley A, Grieben M, Goubin S, Mukhopadhyay S et al. 2015. K2P channel gating mechanisms revealed by structures of TREK-2 and a complex with Prozac. Science, 347 (6227), pp. 1256-1259. | Show Abstract | Read more

TREK-2 (KCNK10/K2P10), a two-pore domain potassium (K2P) channel, is gated by multiple stimuli such as stretch, fatty acids, and pH and by several drugs. However, the mechanisms that control channel gating are unclear. Here we present crystal structures of the human TREK-2 channel (up to 3.4 angstrom resolution) in two conformations and in complex with norfluoxetine, the active metabolite of fluoxetine (Prozac) and a state-dependent blocker of TREK channels. Norfluoxetine binds within intramembrane fenestrations found in only one of these two conformations. Channel activation by arachidonic acid and mechanical stretch involves conversion between these states through movement of the pore-lining helices. These results provide an explanation for TREK channel mechanosensitivity, regulation by diverse stimuli, and possible off-target effects of the serotonin reuptake inhibitor Prozac.

England KS, Tumber A, Krojer T, Scozzafava G, Ng SS, Daniel M, Szykowska A, Che K, von Delft F, Burgess-Brown NA et al. 2014. Optimisation of a triazolopyridine based histone demethylase inhibitor yields a potent and selective KDM2A (FBXL11) inhibitor. Medchemcomm, 5 (12), pp. 1879-1886. | Show Abstract | Read more

A potent inhibitor of the JmjC histone lysine demethylase KDM2A (compound 35, pIC50 7.2) with excellent selectivity over representatives from other KDM subfamilies has been developed; the discovery that a triazolopyridine compound binds to the active site of JmjC KDMs was followed by optimisation of the triazole substituent for KDM2A inhibition and selectivity.

Hay DA, Fedorov O, Martin S, Singleton DC, Tallant C, Wells C, Picaud S, Philpott M, Monteiro OP, Rogers CM et al. 2014. Discovery and optimization of small-molecule ligands for the CBP/p300 bromodomains. J Am Chem Soc, 136 (26), pp. 9308-9319. | Show Abstract | Read more

Small-molecule inhibitors that target bromodomains outside of the bromodomain and extra-terminal (BET) sub-family are lacking. Here, we describe highly potent and selective ligands for the bromodomain module of the human lysine acetyl transferase CBP/p300, developed from a series of 5-isoxazolyl-benzimidazoles. Our starting point was a fragment hit, which was optimized into a more potent and selective lead using parallel synthesis employing Suzuki couplings, benzimidazole-forming reactions, and reductive aminations. The selectivity of the lead compound against other bromodomain family members was investigated using a thermal stability assay, which revealed some inhibition of the structurally related BET family members. To address the BET selectivity issue, X-ray crystal structures of the lead compound bound to the CREB binding protein (CBP) and the first bromodomain of BRD4 (BRD4(1)) were used to guide the design of more selective compounds. The crystal structures obtained revealed two distinct binding modes. By varying the aryl substitution pattern and developing conformationally constrained analogues, selectivity for CBP over BRD4(1) was increased. The optimized compound is highly potent (Kd = 21 nM) and selective, displaying 40-fold selectivity over BRD4(1). Cellular activity was demonstrated using fluorescence recovery after photo-bleaching (FRAP) and a p53 reporter assay. The optimized compounds are cell-active and have nanomolar affinity for CBP/p300; therefore, they should be useful in studies investigating the biological roles of CBP and p300 and to validate the CBP and p300 bromodomains as therapeutic targets.

Rooney TPC, Filippakopoulos P, Fedorov O, Picaud S, Cortopassi WA, Hay DA, Martin S, Tumber A, Rogers CM, Philpott M et al. 2014. A series of potent CREBBP bromodomain ligands reveals an induced-fit pocket stabilized by a cation-π interaction. Angew Chem Int Ed Engl, 53 (24), pp. 6126-6130. | Show Abstract | Read more

The benzoxazinone and dihydroquinoxalinone fragments were employed as novel acetyl lysine mimics in the development of CREBBP bromodomain ligands. While the benzoxazinone series showed low affinity for the CREBBP bromodomain, expansion of the dihydroquinoxalinone series resulted in the first potent inhibitors of a bromodomain outside the BET family. Structural and computational studies reveal that an internal hydrogen bond stabilizes the protein-bound conformation of the dihydroquinoxalinone series. The side chain of this series binds in an induced-fit pocket forming a cation-π interaction with R1173 of CREBBP. The most potent compound inhibits binding of CREBBP to chromatin in U2OS cells.

Guetzoyan L, Ingham RJ, Nikbin N, Rossignol J, Wolling M, Baumert M, Burgess-Brown NA, Strain-Damerell CM, Shrestha L, Brennan PE et al. 2014. Machine-assisted synthesis of modulators of the histone reader BRD9 using flow methods of chemistry and frontal affinity chromatography MEDCHEMCOMM, 5 (4), pp. 540-546. | Show Abstract | Read more

A combination of conventional organic synthesis, remotely monitored flow synthesis and bioassay platforms, were used for the evaluation of novel inhibitors targeting bromodomains outside the well-studied bromodomain and extra terminal (BET) family, here exemplified by activity measurements on the bromodomain of BRD9 protein, a component of some tissue-specific SWi/SNF chromatin remodelling complexes. The Frontal Affinity Chromatography combined with Mass Spectrometry (FAC-MS) method proved to be reliable and results correlated well with an independent thermal shift assay. © 2014 the Partner Organisations.

Yue WW, Froese DS, Brennan PE. 2014. The role of protein structural analysis in the next generation sequencing era Topics in Current Chemistry, 336 pp. 67-98. | Show Abstract | Read more

Proteins are macromolecules that serve a cell's myriad processes and functions in all living organisms via dynamic interactions with other proteins, small molecules and cellular components. Genetic variations in the protein-encoding regions of the human genome account for > 85% of all known Mendelian diseases, and play an influential role in shaping complex polygenic diseases. Proteins also serve as the predominant target class for the design of small molecule drugs to modulate their activity. Knowledge of the shape and form of proteins, by means of their three-dimensional structures, is therefore instrumental to understanding their roles in disease and their potentials for drug development. In this chapter we outline, with the wide readership of non-structural biologists in mind, the various experimental and computational methods available for protein structure determination. We summarize how the wealth of structure information, contributed to a large extent by the technological advances in structure determination to date, serves as a useful tool to decipher the molecular basis of genetic variations for disease characterization and diagnosis, particularly in the emerging era of genomic medicine, and becomes an integral component in the modern day approach towards rational drug development. © Springer-Verlag Berlin Heidelberg 2012.

Discovery of Small Molecule Inhibitors of S100 Proteins

S100 is a family of 21 proteins in humans which perform the diverse functions in regulating cellular responses to external stimuli. The inappropriate activity of various S100 proteins has been linked to a variety of human diseases, from Alzheimer’s to cancers. Despite their important role in human physiology and pathology, only small number of small molecule modulators has been reported in the literature and none are currently in clinical trials.Target Discovery Institute (TDI) and the ...

View project

Structure and Function of AAA ATPases

ATPases Associated with diverse cellular Activities (AAA) represent a diverse family of enzymes involved in a variety of fundamental cellular processes such as signal transduction and gene expression. AAA ATPases utilise the energy generated by nucleotide hydrolysis to remodel the structure of macromolecules or translocate proteins. Several AAA members are linked to the modulation of immunomodulatory processes and cancer progression. As such, these highly conserved proteins are of great ...

View project

1108

Thank you for registering your interest

We were unable to record your request to register for interest in future opportunities. Please try again and if problems persist contact us at webteam@ndm.ox.ac.uk