Iodine scanning of a phenazine inhibitor of vacuolar sorting

Affinity reagents are often used to address the target identification problem in chemical genetics. The design of such reagents so that the linker does not occlude interactions with protein targets is an ongoing challenge. This work describes a systematic approach to synthesize derivatives of a bioactive that should avoid interference with binding to targets and be readily converted to affinity reagents.     

Fatty acid synthase inhibitors of phenolic constituents isolated from Garcinia mangostana

Natural inhibitors of fatty acid synthase (FAS) are emerging as potential therapeutic agents to treat cancer and obesity. The bioassay-guided chemical investigation of the hulls of Garcinia mangostana led to the isolation of 13 phenolic compounds (1–13) mainly including xanthone and benzophenone, in which compounds 7, 8, 9, 10, and 11 were isolated from this plant for the first time and compound 9 was a new natural product. These isolates possess strong inhibitory activity of FAS with the IC₅₀ values ranging from 1.24 to 91.07 μM. The study indicates that two types of natural products, xanthones and benzophenones, could be considered as promising FAS inhibitors.     

Addressing PXR liabilities of phthalazine-based hedgehog/smoothened antagonists using novel pyridopyridazines

Pyridopyridazine antagonists of the hedgehog signaling pathway are described. Designed to optimize our previously described phthalazine smoothened antagonists, a representative compound eliminates a PXR liability while retaining potency and in vitro metabolic stability. Moreover, the compound has improved efficacy in a hedgehog/smoothened signaling mouse pharmacodynamic model.     

A synergistic approach to protein crystallization: Combination of a fixed‐arm carrier with surface entropy reduction

Protein crystallographers are often confronted with recalcitrant proteins not readily crystallizable, or which crystallize in problematic forms. A variety of techniques have been used to surmount such obstacles: crystallization using carrier proteins or antibody complexes, chemical modification, surface entropy reduction, proteolytic digestion, and additive screening. Here we present a synergistic approach for successful crystallization of proteins that do not form diffraction quality crystals using conventional methods. This approach combines favorable aspects of carrier‐driven crystallization with surface entropy reduction. We have generated a series of maltose binding protein (MBP) fusion constructs containing different surface mutations designed to reduce surface entropy and encourage crystal lattice formation. The MBP advantageously increases protein expression and solubility, and provides a streamlined purification protocol. Using this technique, we have successfully solved the structures of three unrelated proteins that were previously unattainable. This crystallization technique represents a valuable rescue strategy for protein structure solution when conventional methods fail.     

(S)-3-(4-(2-(5-Methyl-2-phenyloxazol-4-yl)ethoxy)phenyl)-2-(piperazin-1-yl)propanoic acid compounds: Synthesis and biological evaluation of dual PPARα/γ agonists

A series of novel, potent PPARα/γ dual agonists were synthesized and appraised. The most potent analogue, compound 2b demonstrated EC₅₀ value of 0.012 ± 0.002 and 0.032 ± 0.01 μM, respectively, for hPPARα and hPPARγ in transactivation assay. Additionally, compound 2b demonstrated good glucose and lipid lowering effect in genetic diabetic (db/db) mice.     

Discovery of tetrahydroisoquinoline (THIQ) derivatives as potent and orally bioavailable LFA-1/ICAM-1 antagonists

This letter describes the discovery of a novel series of tetrahydroisoquinoline (THIQ)-derived small molecules that potently inhibit both human T-cell migration and super-antigen induced T-cell activation through disruption of the binding of integrin LFA-1 to its receptor, ICAM-1. In addition to excellent in vitro potency, 6q shows good pharmacokinetic properties and its ethyl ester (6t) demonstrates good oral bioavailability in both mouse and rat. Either intravenous administration of 6q or oral administration of its ethyl ester (6t) produced a significant reduction of neutrophil migration in a thioglycollate-induced murine peritonitis model.     

URG11 promotes gastric cancer growth and invasion by activation of β‐catenin signalling pathway

Upregulated gene 11 (URG11), a new gene upregulated by Heptatitis B Virus X protein (HBx), was previously shown to activate β‐catenin and promote hepatocellular growth and tumourigenesis. Although the oncogenic role of URG11 in the development of hepatocellular carcinoma has been well documented, its relevance to other human malignancies and the underlying molecular mechanisms remain largely unknown. Here we reported a novel function of URG11 to promote gastric cancer growth and metastasis. URG11 was found to be highly expressed in gastric cancer tissues compared with adjacent nontumourous ones by immunohistochemical staining and western blot. Knockdown of URG11 expression by small interfering RNA (siRNA) effectively attenuated the proliferation, anchorage‐independent growth, invasiveness and metastatic potential of gastric cancer cells. URG11 inhibition led to decreased expression of β‐catenin and its nuclear accumulation in gastric cancer cells and extensive costaining between URG11 and β‐catenin was observed in gastric cancer tissues. Transient transfection assays with the β‐catenin promoter showed that it was inhibited by URG11‐specific small inhibitory RNA. Moreover, suppression of endogenous URG11 expression results in decreased activation of β‐catenin/TCF and its downstream effector genes, cyclinD1 and membrane type 1 matrix metallopeptidase (MT1‐MMP), which are known to be involved in cell proliferation and invasion, respectively. Taken together, our data suggest that URG11 contributes to gastric cancer growth and metastasis at least partially through activation of β‐catenin signalling pathway. These findings also propose a promising target for gene therapy in gastric cancer.     

Structural basis for decreased affinity of Emodin binding to Val66-mutated human CK2α as determined by molecular dynamics

Protein kinase CK2 (casein kinase 2) is a multifunctional serine/threonine kinase that is involved in a broad range of physiological events. The decreased affinity of Emodin binding to human CK2α resulting from single-point mutation of Val66 to Ala (V66A) has been demonstrated by experimental mutagenesis. Molecular dynamics (MD) simulations and energy analysis were performed on wild type (WT) and V66A mutant CK2α-Emodin complexes to investigate the subtle influences of amino acid replacement on the structure of the complex. The structure of CK2α and the orientation of Emodin undergo changes to different degrees in V66A mutant. The affected positions in CK2α are mainly distributed over the glycine-rich loop (G-loop), the α-helix and the loop located at the portion between G-loop and α-helix (C-loop). Based on the coupling among these segments, an allosteric mechanism among the C-loop, the G-loop and the deviated Emodin is proposed. Additionally, an estimated energy calculation and residue-based energy decomposition also indicate the lower instability of V66A mutant in contrast to WT, as well as the unfavorable energetic influences on critical residue contributions.