Protein kinase R (PKR)-like endoplasmic reticulum kinase (PERK) is activated in response to a variety of endoplasmic reticulum stresses implicated in numerous disease states. Evidence that PERK is ...implicated in tumorigenesis and cancer cell survival stimulated our search for small molecule inhibitors. Through screening and lead optimization using the human PERK crystal structure, we discovered compound 38 (GSK2606414), an orally available, potent, and selective PERK inhibitor. Compound 38 inhibits PERK activation in cells and inhibits the growth of a human tumor xenograft in mice.
Human genetic evidence shows that PDE3B is associated with metabolic and dyslipidemia phenotypes. A number of PDE3 family selective inhibitors have been approved by the FDA for various indications; ...however, given the undesirable proarrhythmic effects in the heart, selectivity for PDE3B inhibition over closely related family members (such as PDE3A; 48% identity) is a critical consideration for development of PDE3B therapeutics. Selectivity for PDE3B over PDE3A may be achieved in a variety of ways, including properties intrinsic to the compound or tissue-selective targeting. The high (>95%) active site homology between PDE3A and B represents a massive obstacle for obtaining selectivity at the active site; however, utilization of libraries with high molecular diversity in high throughput screens may uncover selective chemical matter. Herein, we employed a DNA-encoded library screen to identify PDE3B-selective inhibitors and identified potent and selective boronic acid compounds bound at the active site.
Proline-specific dipeptidyl peptidases (DPPs) are emerging targets for drug development. DPP4 inhibitors are approved in many countries, and other dipeptidyl peptidases are often referred to as DPP4 ...activity- and/or structure-homologues (DASH). Members of the DASH family have overlapping substrate specificities, and, even though they share low sequence identity, therapeutic or clinical cross-reactivity is a concern. Here, we report the structure of human DPP7 and its complex with a selective inhibitor Dab-Pip (L-2,4-diaminobutyryl-piperidinamide) and compare it with that of DPP4. Both enzymes share a common catalytic domain (α/β-hydrolase). The catalytic pocket is located in the interior of DPP7, deep inside the cleft between the two domains. Substrates might access the active site via a narrow tunnel. The DPP7 catalytic triad is completely conserved and comprises Ser162, Asp418 and His443 (corresponding to Ser630, Asp708 and His740 in DPP4), while other residues lining the catalytic pockets differ considerably. The "specificity domains" are structurally also completely different exhibiting a β-propeller fold in DPP4 compared to a rare, completely helical fold in DPP7. Comparing the structures of DPP7 and DPP4 allows the design of specific inhibitors and thus the development of less cross-reactive drugs. Furthermore, the reported DPP7 structures shed some light onto the evolutionary relationship of prolyl-specific peptidases through the analysis of the architectural organization of their domains.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Ecdysteroid pulses trigger the major developmental transitions during the
Drosophila life cycle. These hormonal responses are thought to be mediated by the ecdysteroid receptor (EcR) and its ...heterodimeric partner Ultraspiracle (USP). We provide evidence for a second ecdysteroid signaling pathway mediated by DHR38, the
Drosophila ortholog of the mammalian NGFI-B subfamily of orphan nuclear receptors. DHR38 also heterodimerizes with USP, and this complex responds to a distinct class of ecdysteroids in a manner that is independent of EcR. This response is unusual in that it does not involve direct binding of ecdysteroids to either DHR38 or USP. X-ray crystallographic analysis of DHR38 reveals the absence of both a classic ligand binding pocket and coactivator binding site, features that seem to be common to all NGFI-B subfamily members. Taken together, these data reveal the existence of a separate structural class of nuclear receptors that is conserved from fly to humans.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Nicotinamide riboside (NR) and nicotinic acid riboside (NAR) are hydrolyzed by hCD157.•The enzyme hydrolyzes NR with a kcat/KM of 17μM−1s−1. NR is the preferred substrate for hCD157.•The long ...half-life (7s) of the catalytic intermediate suggests that hydrolysis proceeds through a covalent intermediate.
hCD157 catalyzes the hydrolysis of nicotinamide riboside (NR) and nicotinic acid riboside (NAR). The release of nicotinamide or nicotinic acid from NR or NAR was confirmed by spectrophotometric, HPLC and NMR analyses. hCD157 is inactivated by a mechanism-based inhibitor, 2′-deoxy-2′-fluoro-nicotinamide arabinoside (fNR). Modification of the enzyme during the catalytic cycle by NR, NAR, or fNR increased the intrinsic protein fluorescence by approximately 50%. Pre-steady state and steady state data were used to derive a minimal kinetic scheme for the hydrolysis of NR. After initial complex formation a reversible step (360 and 30s−1) is followed by a slow irreversible step (0.1s−1) that defined the rate limiting step, or kcat. The calculated KMapp value for NR in the hydrolytic reaction is 6nM. The values of the kinetic constants suggest that one biological function of cell-surface hCD157 is to bind and slowly hydrolyze NR, possibly converting it to a ligand-activated receptor. Differences in substrate preference between hCD157 and hCD38 were rationalized through a comparison of the crystal structures of the two proteins. This comparison identified several residues in hCD157 (F108 and F173) that can potentially hinder the binding of dinucleotide substrates (NAD+).
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
1-(1,3,5-Triazin-yl)piperidine-4-carboxamide inhibitors of soluble epoxide hydrolase were identified from high through-put screening using encoded library technology. The triazine heterocycle proved ...to be a critical functional group, essential for high potency and P450 selectivity. Phenyl group substitution was important for reducing clearance, and establishing good oral exposure. Based on this lead optimization work, 1-4-methyl-6-(methylamino)-1,3,5-triazin-2-yl-N-{4-bromo-2-(trifluoromethoxy)-phenylmethyl}-4-piperidinecarboxamide (27) was identified as a useful tool compound for in vivo investigation. Robust effects on a serum biomarker, 9, 10-epoxyoctadec-12(Z)-enoic acid (the epoxide derived from linoleic acid) were observed, which provided evidence of robust in vivo target engagement and the suitability of 27 as a tool compound for study in various disease models.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Starting from the micromolar 8-quinoline carboxamide high-throughput screening hit 1a, a systematic exploration of the structure–activity relationships (SAR) of the 4-, 6-, and 8-substituents of the ...quinoline ring resulted in the identification of approximately 10–100-fold more potent human CD38 inhibitors. Several of these molecules also exhibited pharmacokinetic parameters suitable for in vivo animal studies, including low clearances and decent oral bioavailability. Two of these CD38 inhibitors, 1ah and 1ai, were shown to elevate NAD tissue levels in liver and muscle in a diet-induced obese (DIO) C57BL/6 mouse model. These inhibitor tool compounds will enable further biological studies of the CD38 enzyme as well as the investigation of the therapeutic implications of NAD enhancement in disease models of abnormally low NAD.
An X-ray crystal structure is reported for the novel enhanced-affinity glucocorticoid agonist fluticasone furoate (FF) in the ligand binding domain of the glucocorticoid receptor. Comparison of this ...structure with those of dexamethasone and fluticasone propionate shows the 17α furoate ester to occupy more fully the lipophilic 17α pocket on the receptor, which may account for the enhanced glucocorticoid receptor binding of FF.
Analysis of the x-ray crystal structure of mono-substituted acetylenic thienopyrimidine 6 complexed with the ErbB family enzyme ErbB-4 revealed a covalent bond between the terminal carbon of the ...acetylene moiety and the sulfhydryl group of Cys-803 at the solvent interface. The identification of this covalent adduct suggested that acetylenic thienopyrimidine 6 and related analogs might also be capable of forming an analogous covalent adduct with EGFR, which has a conserved cysteine (797) near the ATP binding pocket. To test this hypothesis, we treated a truncated, catalytically competent form of EGFR (678-1020) with a structurally related propargylic amine (8). An investigation of the resulting complex by mass spectrometry revealed the formation of a covalent complex of thienopyrimidine 8 with Cys-797 of EGFR. This finding enabled us to readily assess the irreversibility of various inhibitors and also facilitated a structure-activity relationship understanding of the covalent modifying potential and biological activity of a series of acetylenic thienopyrimidine compounds with potent antitumor activity. Several ErbB family enzyme and cell potent 6-ethynyl thienopyrimidine kinase inhibitors were found to form covalent adducts with EGFR.
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BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
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With the goal of discovering more selective anti-inflammatory drugs, than COX inhibitors, to attenuate prostaglandin signaling, a fragment-based screen of hematopoietic prostaglandin ...D synthase was performed. The 76 crystallographic hits were sorted into similar groups, with the 3-cyano-quinoline 1a (FP IC50 = 220,000 nM, LE = 0.43) being a potent member of the 6,6-fused heterocyclic cluster. Employing SAR insights gained from structural comparisons of other H-PGDS fragment binding mode clusters, the initial hit 1a was converted into the 70-fold more potent quinoline 1d (IC50 = 3,100 nM, LE = 0.49). A systematic substitution of the amine moiety of 1d, utilizing structural information and array chemistry, with modifications to improve inhibitor stability, resulted in the identification of the 300-fold more active H-PGDS inhibitor tool compound 1bv (IC50 = 9.9 nM, LE = 0.42). This selective inhibitor exhibited good murine pharmacokinetics, dose-dependently attenuated PGD2 production in a mast cell degranulation assay and should be suitable to further explore H-PGDS biology.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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![6-Ethynylthieno[3,2-d]- and...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/0027-8424_1091-6490/small "6-Ethynylthieno[3,2-d]- and 6-ethynylthieno[2,3-d]pyrimidin-4-anilines as tunable covalent modifiers of ErbB kinases")
