Discovery and optimization of a series of 2-aminothiazole-oxazoles as potent phosphoinositide 3-kinase γ inhibitors

A novel series of 2-aminothiazole-oxazoles was designed and synthesized as part of efforts to develop potent phosphoinositide 3-kinase γ (PI3Kγ) inhibitors. The modification of a high-throughput screening hit, compound 1, resulted in the identification of compounds 10 and 15, which displayed potent inhibitory activities in enzyme-based and cell-based assays.     

Hypertrophy and unconventional cell division of hepatocytes underlie liver regeneration

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Highlights? Not all hepatocytes undergo cell division during liver regeneration ? Hypertrophy precedes proliferation in the regenerating liver ? Hepatocytes infrequently enter into M phase during liver regeneration ? Binuclear hepatocytes undergo cell division to generate mononuclear hepatocytes     

Structure-activity relationships and key structural feature of pyridyloxybenzene-acylsulfonamides as new, potent, and selective peroxisome proliferator-activated receptor (PPAR) γ Agonists

In our search for a novel class of non-TZD, non-carboxylic acid peroxisome proliferator-activated receptor (PPAR) γ agonists, we explored alternative lipophilic templates to replace benzylpyrazole core of the previously reported agonist 1. Introduction of a pentylsulfonamide group into arylpropionic acids derived from previous in-house PPARγ ligands succeeded in the identification of 2-pyridyloxybenzene-acylsulfonamide 2 as a lead compound. Docking studies of compound 2 suggested that a substituent para to the central benzene ring should be incorporated to effectively fill the Y-shaped cavity of the PPARγ ligand-binding domain (LBD). This strategy led to significant improvement of PPARγ activity. Further optimization to balance in vitro activity and metabolic stability allowed the discovery of the potent, selective and orally efficacious PPARγ agonist 8f. Structure-activity relationship study as well as detailed analysis of the binding mode of 8f to the PPARγ-LBD revealed the essential structural features of this series of ligands.     

Remarkable enhancement in PLD activity from Streptoverticillium cinnamoneum by substituting serine residue into the GG/GS motif

The gene that encodes phospholipase D (PLD) from Streptoverticillium cinnamoneum contains three consensus regions (Region I, II and IV as shown in Fig. 1A) that are conserved among the PLD superfamily. The glycine-glycine (GG) motif in Region I and the glycine-serine (GS) motif in Region IV are also conserved in the PLD superfamily. These (GG and GS) motifs are located 7 residues downstream from each HKD motif. In an investigation of fifteen GG/GS motif mutants, generated as fusion proteins with maltose-binding protein (MBP-PLDs), three highly active mutants were identified. Three of the mutants (G215S, G216S, and G216S-S489G) contained a serine residue in the GG motif, and exhibited approximately a 9-27-fold increased transphosphatidylation activity to DPPC compared with recombinant wild type MBP-PLD. When heat stability was compared between three mutants and the recombinant wild type, only G216S-S489G showed heat labile properties. It appears that the 489th serine residue in the GS motif also contributes to the thermal stability of the enzyme. In addition, the GG/GS motif was very close to the active center residue, including two HKD motifs, as shown by computer modeling. The findings suggest that the GG/GS motif of PLD is a key motif that affects catalytic function and enzymatic stability.     

ASK1 is activated by arsenic trioxide in leukemic cells through accumulation of reactive oxygen species and may play a negative role in induction of apoptosis

Arsenic trioxide (ATO) is remarkably effective for treating acute promyelocytic leukemia. Here, we find that ATO treatment of NB4 and K562 leukemic cells induces activation of ASK1. ASK1 activation was induced most significantly at low concentrations of ATO, where G2/M arrest but not apoptosis was induced. On the other hand, ATO barely activated ASK1 at high concentrations, where apoptosis as well as activation of JNK and p38 was induced significantly. ATO-induced accumulation of reactive oxygen species (ROS), while the ASK1 activation was suppressed by cotreatment with an antioxidant, N-acetyl-l-cysteine. Murine embryonic fibroblasts (MEFs) from ASK1-deficient mice were more susceptible to ATO-induced apoptosis than control MEFs. Furthermore, ATO at the low concentration induced significant apoptosis in K562 cells when ASK1 was knocked down by siRNA. These results indicate that ASK1 is activated by ATO through ROS accumulation and may negatively regulate apoptosis in leukemic cells without activating p38 and JNK.     

Corticosteroid enhances heme oxygenase-1 production by circulating monocytes by up-regulating hemoglobin scavenger receptor and amplifying the receptor-mediated uptake of hemoglobin-haptoglobin complex

This study examined the relationship between steroid treatment and CD163-mediated downstream pathways linked to inflammatory resolution. Twelve patients referred for congenital heart disease surgery were divided into two groups based on the severity of intravascular hemolysis during cardiopulmonary bypass surgery. Patients with severe intravascular hemolysis were administered haptoglobin during the procedure. Flow cytometry indicated a peak in monocyte CD163 expression on post-operative day 1 in both groups. Enhanced and prolonged heme oxygenase-1 (HO-1) mRNA expression levels were observed in patients who received haptoglobin. Binding of hemoglobin-haptoglobin complex (Hb/Hp) to CD163 resulted in significant induction of HO-1 by peripheral blood mononuclear cells after exposure to dexamethasone prior to culture. This effect was significantly inhibited by anti-CD163 antibody. Our results demonstrated up-regulation of CD163 expression on the monocyte surface by steroid treatment. Steroid treatment was suggested to facilitate CD163-mediated endocytosis of hemoglobin to monocytes/macrophages and thereby induce acceleration of HO-1 synthesis.     

Production of a soluble recombinant prion protein fused to blue fluorescent protein without refolding or detergents in Escherichia coli cells

The physiological function of prion proteins (PrP) remains unclear. To investigate the physiological relevance of PrP, we constructed a fusion protein of PrP with enhanced blue fluorescent protein (PrP-EBFP) to quantify the interaction of PrP with other molecules. Production of soluble PrP-EBFP was achieved by lowering the expression temperature in Escherichia coli (E. coli) cells to 15 degrees C. Soluble PrP-EBFP was purified on cation exchange and heparin-affinity columns to yield high purity protein. This is the first report of the preparation of soluble recombinant PrP without refolding following solubilization using denaturants or disruption using detergents. To confirm the integrity of PrP-EBFP, anisotropy was estimated under physiological conditions in the presence of heparin, which interacts with PrP. The dissociation constant was determined to be 0.88+/-0.07 microM. PrP-EBFP should be useful in the quantification of PrP interactions with other molecules.     

Increased apoptosis and angiogenesis in gastric low-grade mucosa-associated lymphoid tissue-type lymphoma by Helicobacter heilmannii infection in C57/BL6 mice

Helicobacter heilmannii has been reported to cause gastric low-grade mucosa-associated lymphoid tissue-type (MALT) lymphoma, but its precise pathophysiological mechanism remains to be clarified. We recently established a model of gastric B-cell MALT lymphoma in C57BL/6 mice by means of peroral infection of H. heilmannii primarily obtained from cynomolgus monkeys. Using this model, macroscopic, immunohistochemical, and electron microscopic observations of MALT lymphomas were carried out in order to examine the development of apoptosis and angiogenesis. Enhancement of the microvascular network and an increase in vascular endothelial growth factor-A were detected in the central region of the MALT lymphoma tissue in the infected mouse stomach, while vascular endothelial growth factor-C was detected at the margins of the MALT lymphomas. In addition, many H. heilmannii-invaded parietal cells showed caspase-3 immunoreactivity in the fundic mucosal tissue surrounding the MALT lymphoma. In conclusion, in H. heilmannii-induced MALT lymphoma, enhanced immunoreactivity of vascular endothelial growth factor-A and factor-C was observed in areas encircled by increased parietal cell apoptosis, which indicates the pathophysiological relevance of both angiogenesis and apoptosis in MALT lymphoma formation.     

Cdk5 is required for multipolar-to-bipolar transition during radial neuronal migration and proper dendrite development of pyramidal neurons in the cerebral cortex

The mammalian cerebral cortex consists of six layers that are generated via coordinated neuronal migration during the embryonic period. Recent studies identified specific phases of radial migration of cortical neurons. After the final division, neurons transform from a multipolar to a bipolar shape within the subventricular zone-intermediate zone (SVZ-IZ) and then migrate along radial glial fibres. Mice lacking Cdk5 exhibit abnormal corticogenesis owing to neuronal migration defects. When we introduced GFP into migrating neurons at E14.5 by in utero electroporation, we observed migrating neurons in wild-type but not in Cdk5(-/-) embryos after 3-4 days. Introduction of the dominant-negative form of Cdk5 into the wild-type migrating neurons confirmed specific impairment of the multipolar-to-bipolar transition within the SVZ-IZ in a cell-autonomous manner. Cortex-specific Cdk5 conditional knockout mice showed inverted layering of the cerebral cortex and the layer V and callosal neurons, but not layer VI neurons, had severely impaired dendritic morphology. The amount of the dendritic protein Map2 was decreased in the cerebral cortex of Cdk5-deficient mice, and the axonal trajectory of cortical neurons within the cortex was also abnormal. These results indicate that Cdk5 is required for proper multipolar-to-bipolar transition, and a deficiency of Cdk5 results in abnormal morphology of pyramidal neurons. In addition, proper radial neuronal migration generates an inside-out pattern of cerebral cortex formation and normal axonal trajectories of cortical pyramidal neurons.