Chemical Biology Publications 2011

Philpott M, Yang J, Tumber T, Fedorov O, Uttarkar S, Filippakopoulos P, Picaud S, Keates T, Felletar I, Ciulli A et al. 2011. Bromodomain-peptide displacement assays for interactome mapping and inhibitor discovery. Molecular bioSystems, 7 (10), pp. 2899-2908. | Citations: 88 (Scopus) | Show Abstract | Read more

Histone lysine acetylation is a key component of epigenetic regulation of gene transcription. Bromodomains, found in histone acetyl transferases and other chromatin-associated proteins, bind selectively to acetylated lysines, acting as "readers" of the histone code, and have recently been shown to contain a druggable binding pocket. Here we report the development of high-throughput assays that quantify the binding of bromodomains to acetylated histone peptides. We have used these assays to screen for histone binding partners of as yet uncharacterized bromodomains, adding to current knowledge of the histone code and expanding the repertoire of assays for chemical probe discovery. We have also demonstrated that these assays can be used to detect small molecule binding from the very weak to the nanomolar range. This assay methodology is thereby anticipated to provide the basis both for broader interactome profiling and for small molecule inhibitor discovery.

Muller S, Filippakopoulos P, Knapp S. 2011. Bromodomains as therapeutic targets. Expert Rev Mol Med, 13 pp. e29. | Citations: 214 (Scopus) | Show Abstract | Read more

Acetylation of lysine residues is a post-translational modification with broad relevance to cellular signalling and disease biology. Enzymes that 'write' (histone acetyltransferases, HATs) and 'erase' (histone deacetylases, HDACs) acetylation sites are an area of extensive research in current drug development, but very few potent inhibitors that modulate the 'reading process' mediated by acetyl lysines have been described. The principal readers of ɛ-N-acetyl lysine (K(ac)) marks are bromodomains (BRDs), which are a diverse family of evolutionary conserved protein-interaction modules. The conserved BRD fold contains a deep, largely hydrophobic acetyl lysine binding site, which represents an attractive pocket for the development of small, pharmaceutically active molecules. Proteins that contain BRDs have been implicated in the development of a large variety of diseases. Recently, two highly potent and selective inhibitors that target BRDs of the BET (bromodomains and extra-terminal) family provided compelling data supporting targeting of these BRDs in inflammation and in an aggressive type of squamous cell carcinoma. It is likely that BRDs will emerge alongside HATs and HDACs as interesting targets for drug development for the large number of diseases that are caused by aberrant acetylation of lysine residues.

Hewings DS, Wang M, Philpott M, Fedorov O, Uttarkar S, Filippakopoulos P, Picaud S, Vuppusetty C, Marsden B, Knapp S et al. 2011. 3,5-dimethylisoxazoles act as acetyl-lysine-mimetic bromodomain ligands. J Med Chem, 54 (19), pp. 6761-6770. | Citations: 138 (Scopus) | Show Abstract | Read more

Histone-lysine acetylation is a vital chromatin post-translational modification involved in the epigenetic regulation of gene transcription. Bromodomains bind acetylated lysines, acting as readers of the histone-acetylation code. Competitive inhibitors of this interaction have antiproliferative and anti-inflammatory properties. With 57 distinct bromodomains known, the discovery of subtype-selective inhibitors of the histone-bromodomain interaction is of great importance. We have identified the 3,5-dimethylisoxazole moiety as a novel acetyl-lysine bioisostere, which displaces acetylated histone-mimicking peptides from bromodomains. Using X-ray crystallographic analysis, we have determined the interactions responsible for the activity and selectivity of 4-substituted 3,5-dimethylisoxazoles against a selection of phylogenetically diverse bromodomains. By exploiting these interactions, we have developed compound 4d, which has IC(50) values of <5 μM for the bromodomain-containing proteins BRD2(1) and BRD4(1). These compounds are promising leads for the further development of selective probes for the bromodomain and extra C-terminal domain (BET) family and CREBBP bromodomains.

Philpott M, Yang J, Tumber T, Fedorov O, Uttarkar S, Filippakopoulos P, Picaud S, Keates T, Felletar I, Ciulli A et al. 2011. Bromodomain-peptide displacement assays for interactome mapping and inhibitor discovery. Mol Biosyst, 7 (10), pp. 2899-2908. | Show Abstract | Read more

Histone lysine acetylation is a key component of epigenetic regulation of gene transcription. Bromodomains, found in histone acetyl transferases and other chromatin-associated proteins, bind selectively to acetylated lysines, acting as "readers" of the histone code, and have recently been shown to contain a druggable binding pocket. Here we report the development of high-throughput assays that quantify the binding of bromodomains to acetylated histone peptides. We have used these assays to screen for histone binding partners of as yet uncharacterized bromodomains, adding to current knowledge of the histone code and expanding the repertoire of assays for chemical probe discovery. We have also demonstrated that these assays can be used to detect small molecule binding from the very weak to the nanomolar range. This assay methodology is thereby anticipated to provide the basis both for broader interactome profiling and for small molecule inhibitor discovery.

Miduturu CV, Deng X, Kwiatkowski N, Yang W, Brault L, Filippakopoulos P, Chung E, Yang Q, Schwaller J, Knapp S et al. 2011. High-throughput kinase profiling: a more efficient approach toward the discovery of new kinase inhibitors. Chem Biol, 18 (7), pp. 868-879. | Citations: 60 (Scopus) | Show Abstract | Read more

Selective protein kinase inhibitors have only been developed against a small number of kinase targets. Here we demonstrate that "high-throughput kinase profiling" is an efficient method for the discovery of lead compounds for established as well as unexplored kinase targets. We screened a library of 118 compounds constituting two distinct scaffolds (furan-thiazolidinediones and pyrimido-diazepines) against a panel of 353 kinases. A distinct kinase selectivity profile was observed for each scaffold. Selective inhibitors were identified with submicromolar cellular activity against PIM1, ERK5, ACK1, MPS1, PLK1-3, and Aurora A,B kinases. In addition, we identified potent inhibitors for so far unexplored kinases such as DRAK1, HIPK2, and DCAMKL1 that await further evaluation. This inhibitor-centric approach permits comprehensive assessment of a scaffold of interest and represents an efficient and general strategy for identifying new selective kinase inhibitors.

Debdab M, Carreaux F, Renault S, Soundararajan M, Fedorov O, Filippakopoulos P, Lozach O, Babault L, Tahtouh T, Baratte B et al. 2011. Leucettines, a class of potent inhibitors of cdc2-like kinases and dual specificity, tyrosine phosphorylation regulated kinases derived from the marine sponge leucettamine B: modulation of alternative pre-RNA splicing. J Med Chem, 54 (12), pp. 4172-4186. | Citations: 84 (Scopus) | Show Abstract | Read more

We here report on the synthesis, optimization, and biological characterization of leucettines, a family of kinase inhibitors derived from the marine sponge leucettamine B. Stepwise synthesis of analogues starting from the natural structure, guided by activity testing on eight purified kinases, led to highly potent inhibitors of CLKs and DYRKs, two families of kinases involved in alternative pre-mRNA splicing and Alzheimer's disease/Down syndrome. Leucettine L41 was cocrystallized with CLK3. It interacts with key residues located within the ATP-binding pocket of the kinase. Leucettine L41 inhibits the phosphorylation of serine/arginine-rich proteins (SRp), a family of proteins regulating pre-RNA splicing. Indeed leucettine L41 was demonstrated to modulate alternative pre-mRNA splicing, in a cell-based reporting system. Leucettines should be further explored as pharmacological tools to study and modulate pre-RNA splicing. Leucettines may also be investigated as potential therapeutic drugs in Alzheimer's disease (AD) and in diseases involving abnormal pre-mRNA splicing.

Lopez-Ramos M, Prudent R, Moucadel V, Sautel CF, Barette C, Lafanechere L, Mouawad L, Grierson D, Schmidt F, Florent J-C et al. 2011. New potent dual inhibitors of CK2 and Pim kinases: discovery and structural insights (September, pg 3175, 2010) FASEB JOURNAL, 25 (5), pp. 1775-1775. | Read more

Feng L, Geisselbrecht Y, Blanck S, Wilbuer A, Atilla-Gokcumen GE, Filippakopoulos P, Kräling K, Celik MA, Harms K, Maksimoska J et al. 2011. Structurally sophisticated octahedral metal complexes as highly selective protein kinase inhibitors. J Am Chem Soc, 133 (15), pp. 5976-5986. | Citations: 138 (Scopus) | Show Abstract | Read more

The generation of synthetic compounds with exclusive target specificity is an extraordinary challenge of molecular recognition and demands novel design strategies, in particular for large and homologous protein families such as protein kinases with more than 500 members. Simple organic molecules often do not reach the necessary sophistication to fulfill this task. Here, we present six carefully tailored, stable metal-containing compounds in which unique and defined molecular geometries with natural-product-like structural complexity are constructed around octahedral ruthenium(II) or iridium(III) metal centers. Each of the six reported metal compounds displays high selectivity for an individual protein kinase, namely GSK3α, PAK1, PIM1, DAPK1, MLCK, and FLT4. Although being conventional ATP-competitive inhibitors, the combination of the unusual globular shape and rigidity characteristics, of these compounds facilitates the design of highly selective protein kinase inhibitors. Unique structural features of the octahedral coordination geometry allow novel interactions with the glycine-rich loop, which contribute significantly to binding potencies and selectivities. The sensitive correlation between metal coordination sphere and inhibition properties suggests that in this design, the metal is located at a "hot spot" within the ATP binding pocket, not too close to the hinge region where globular space is unavailable, and at the same time not too far out toward the solvent where the octahedral coordination sphere would not have a significant impact on potency and selectivity. This study thus demonstrates that inert (stable) octahedral metal complexes are sophisticated structural scaffolds for the design of highly selective chemical probes.

Salah E, Ugochukwu E, Barr AJ, von Delft F, Knapp S, Elkins JM. 2011. Crystal structures of ABL-related gene (ABL2) in complex with imatinib, tozasertib (VX-680), and a type I inhibitor of the triazole carbothioamide class. J Med Chem, 54 (7), pp. 2359-2367. | Citations: 16 (Scopus) | Show Abstract | Read more

ABL2 (also known as ARG (ABL related gene)) is closely related to the well-studied Abelson kinase cABL. ABL2 is involved in human neoplastic diseases and is deregulated in solid tumors. Oncogenic gene translocations occur in acute leukemia. So far no structural information for ABL2 has been reported. To elucidate structural determinants for inhibitor interaction, we determined the cocrystal structure of ABL2 with the oncology drug imatinib. Interestingly, imatinib not only interacted with the ATP binding site of the inactive kinase but was also bound to the regulatory myristate binding site. This structure may therefore serve as a tool for the development of allosteric ABL inhibitors. In addition, we determined the structures of ABL2 in complex with VX-680 and with an ATP-mimetic type I inhibitor, which revealed an interesting position of the DFG motif intermediate between active and inactive conformations, that may also serve as a template for future inhibitor design.

Deutsch GB, Zielonka EM, Coutandin D, Weber TA, Schäfer B, Hannewald J, Luh LM, Durst FG, Ibrahim M, Hoffmann J et al. 2011. DNA damage in oocytes induces a switch of the quality control factor TAp63α from dimer to tetramer. Cell, 144 (4), pp. 566-576. | Citations: 65 (Scopus) | Show Abstract | Read more

TAp63α, a homolog of the p53 tumor suppressor, is a quality control factor in the female germline. Remarkably, already undamaged oocytes express high levels of the protein, suggesting that TAp63α's activity is under tight control of an inhibitory mechanism. Biochemical studies have proposed that inhibition requires the C-terminal transactivation inhibitory domain. However, the structural mechanism of TAp63α inhibition remains unknown. Here, we show that TAp63α is kept in an inactive dimeric state. We reveal that relief of inhibition leads to tetramer formation with ∼20-fold higher DNA affinity. In vivo, phosphorylation-triggered tetramerization of TAp63α is not reversible by dephosphorylation. Furthermore, we show that a helix in the oligomerization domain of p63 is crucial for tetramer stabilization and competes with the transactivation domain for the same binding site. Our results demonstrate how TAp63α is inhibited by complex domain-domain interactions that provide the basis for regulating quality control in oocytes.

Fedorov O, Huber K, Eisenreich A, Filippakopoulos P, King O, Bullock AN, Szklarczyk D, Jensen LJ, Fabbro D, Trappe J et al. 2011. Specific CLK inhibitors from a novel chemotype for regulation of alternative splicing. Chem Biol, 18 (1), pp. 67-76. | Citations: 121 (Scopus) | Show Abstract | Read more

There is a growing recognition of the importance of protein kinases in the control of alternative splicing. To define the underlying regulatory mechanisms, highly selective inhibitors are needed. Here, we report the discovery and characterization of the dichloroindolyl enaminonitrile KH-CB19, a potent and highly specific inhibitor of the CDC2-like kinase isoforms 1 and 4 (CLK1/CLK4). Cocrystal structures of KH-CB19 with CLK1 and CLK3 revealed a non-ATP mimetic binding mode, conformational changes in helix αC and the phosphate binding loop and halogen bonding to the kinase hinge region. KH-CB19 effectively suppressed phosphorylation of SR (serine/arginine) proteins in cells, consistent with its expected mechanism of action. Chemical inhibition of CLK1/CLK4 generated a unique pattern of splicing factor dephosphorylation and had at low nM concentration a profound effect on splicing of the two tissue factor isoforms flTF (full-length TF) and asHTF (alternatively spliced human TF).

Zadjali F, Pike ACW, Vesterlund M, Sun J, Wu C, Li SSC, Rönnstrand L, Knapp S, Bullock AN, Flores-Morales A. 2011. Structural basis for c-KIT inhibition by the suppressor of cytokine signaling 6 (SOCS6) ubiquitin ligase. J Biol Chem, 286 (1), pp. 480-490. | Citations: 34 (Scopus) | Show Abstract | Read more

The c-KIT receptor tyrosine kinase mediates the cellular response to stem cell factor (SCF). Whereas c-KIT activity is important for the proliferation of hematopoietic cells, melanocytes and germ cells, uncontrolled c-KIT activity contributes to the growth of diverse human tumors. Suppressor of cytokine signaling 6 (SOCS6) is a member of the SOCS family of E3 ubiquitin ligases that can interact with c-KIT and suppress c-KIT-dependent pathways. Here, we analyzed the molecular mechanisms that determine SOCS6 substrate recognition. Our results show that the SH2 domain of SOCS6 is essential for its interaction with c-KIT pY568. The 1.45-Å crystal structure of SOCS6 SH2 domain bound to the c-KIT substrate peptide (c-KIT residues 564-574) revealed a highly complementary and specific interface giving rise to a high affinity interaction (K(d) = 0.3 μm). Interestingly, the SH2 binding pocket extends to substrate residue position pY+6 and envelopes the c-KIT phosphopeptide with a large BG loop insertion that contributes significantly to substrate interaction. We demonstrate that SOCS6 has ubiquitin ligase activity toward c-KIT and regulates c-KIT protein turnover in cells. Our data support a role of SOCS6 as a feedback inhibitor of SCF-dependent signaling and provides molecular data to account for target specificity within the SOCS family of ubiquitin ligases.

Total publications on this page: 12

Total citations for publications on this page: 958