Discovery of N-propylurea 3-benzylpiperidines as selective CC chemokine receptor-3 (CCR3) antagonists

The discovery of novel and selective small molecule antagonists of the CC Chemokine Receptor-3 (CCR3) is presented. Simple conversion from a 4- to 3-benzylpiperidine gave improved selectivity for CCR3 over the serotonin 5HT(2A) receptor. Chiral resolution and exploration of mono- and disubstitution of the N-propylurea resulted in several 3-benzylpiperidine N-propylureas with CCR3 binding IC(50)s under 5 nM. Data from in vitro calcium mobilization and chemotaxis assays for these compounds ranged from high picomolar to low nanomolar EC(50)s and correlated well with antagonist binding IC(50)s.     

Synthesis and biological activity of new quinoxaline antibiotics of echinomycin analogues

Novel quinoxaline antibiotics having the methylenedithioether bridge as an analogue of echinomycin have been synthesized by insertion of methylene moiety between -S-S- bond. The compound 1a shows remarkable cytotoxicities against human tumor various cell lines, and is active VRE (vancomycin-resistant enterococci) within MIC range 0.5-8 microg/mL. According to the eukaryotic or prokaryotic data, 1a might be a first analogue to replace echinomycin.     

Suppression of ceramide-induced cell death by hepatitis C virus core protein

The hepatitis C virus (HCV) core protein is believed to be one of viral proteins that are capable of preventing virus-infected cell death upon various stimuli. But, the effect of the HCV core protein on apoptosis that is induced by various stimuli is contradictory. We examined the possibility that the HCV core protein affects the ceramide-induced cell death in cells expressing the HCV core protein through the sphingomyelin pathway. Cell death that is induced by C(2)-ceramide and bacterial sphingomyelinase was analyzed in 293 cells that constitutively expressed the HCV core protein and compared with 293 cells that were stably transfected only with the expression vector. The HCV core protein inhibited the cell death that was induced by these reagents. The protective effects of the HCV core protein on ceramide-induced cell death were reflected by the reduced expression of p21(WAF1/Cip1/Sid1) and the sustained expression of the Bcl-2 protein in the HCV core-expressing cells with respect to the vector-transfected cells. These results suggest that the HCV core protein in 293 cells plays a role in the modulation of the apoptotic response that is induced by ceramide. Also, the ability of the HCV core protein to suppress apoptosis might have important implications in understanding the pathogenesis of the HCV infection.     

Ethylene biosynthesis in a chilling-sensitive<Emphasis Type="Italic">Arabidopsis</Emphasis> mutant,<Emphasis Type="Italic">chs4-2</Emphasis>

We investigated chilling-induced changes in ethylene levels in Arabidopsis to find plants with distinct patterns of ethylene production in the cold-related biosynthetic pathway. The sensitive mutants identified here includedchs1-2,chs4-2, andchs6-2. Among these, plants of thechs4-2 mutant produced more ethylene than did the wild type after both were transferred from 4°C or 10°C to 22°C. This mutant also showed less freezing tolerance and more electrolyte leakage than the wild-type plants. Our results suggest a relationship between ethylene biosynthesis and chilling sensitivity in the mutant To determine which of the enzymes involved in ethylene biosynthesis were induced by chilling, we tested the activities of ACC synthase and ACC oxidase in both mutant and wild-type plants, and found greater activity by ACC synthase as well as a higher ACC content in the mutants after all the plants were transferred from 10°C to 22°C. However, ACC oxidase activity did not differ between mutant and wild-type plants in response to chilling treatment Therefore, we conclude thatchs4-2 mutants produce more ethylene than do other mutants or the wild type during their recovery from chilling conditions. Furthermore, we believe that ACC synthase is the key enzyme involved in this response.     

Structural basis of sugar-recognizing ubiquitin ligase

SCF(Fbs1) is a ubiquitin ligase that functions in the endoplasmic reticulum (ER)-associated degradation pathway. Fbs1/Fbx2, a member of the F-box proteins, recognizes high-mannose oligosaccharides. Efficient binding to an N-glycan requires di-N-acetylchitobiose (chitobiose). Here we report the crystal structures of the sugar-binding domain (SBD) of Fbs1 alone and in complex with chitobiose. The SBD is composed of a ten-stranded antiparallel beta-sandwich. The structure of the SBD-chitobiose complex includes hydrogen bonds between Fbs1 and chitobiose and insertion of the methyl group of chitobiose into a small hydrophobic pocket of Fbs1. Moreover, NMR spectroscopy has demonstrated that the amino acid residues adjoining the chitobiose-binding site interact with the outer branches of the carbohydrate moiety. Considering that the innermost chitobiose moieties in N-glycans are usually involved in intramolecular interactions with the polypeptide moieties, we propose that Fbs1 interacts with the chitobiose in unfolded N-glycoprotein, pointing the protein moiety toward E2 for ubiquitination.     

Distribution of neuronal nitric oxide synthase-immunoreactive neurons in the cerebral cortex and hippocampus during postnatal development

Although many reports have argued a role for nitric oxide (NO) during postnatal development, there has been no combined demonstration in the cerebral cortex and hippocampus. We have investigated the distribution and morphology of neurons and fibers expressing neuronal NO synthase (nNOS) in the cerebral cortex and hippocampal formation of rats during the postnatal development, and correlated these findings with developmental events taking place in these regions. In the cerebral cortex, the nNOS-immunoreactive cells could be divided into two classes : heavily stained neurons and lightly stained neurons. For the lightly stained nNOS-positive neurons, only the cell bodies were observed, whereas for the heavily stained neurons, the cell bodies and their dendrites were visible. During the postnatal days, heavily stained neurons reached their typical morphology in the second week and appeared in all layers except for layer I. In the hippocampus, there was a transient expression of nNOS in the pyramidal cell layer at P3â€P7, and this expression disappeared during following days. The adult pattern of staining developed gradually during the postnatal period. This study suggested that these alterations might reflect a region-specific role of NO and a potential developmental role in the postnatal cerebral cortex and hippocampus     

Morphology of elastic poly(L-lactide-co-epsilon-caprolactone) copolymers and in vitro and in vivo degradation behavior of their scaffolds

Very elastic PLCL [poly(L-lactide-co-epsilon-caprolactone), 50:50] copolymers were synthesized and extruded into porous tubular scaffolds (pore size 150 +/- 50 microm, porosity 90%) for the application to tissue engineering. The copolymers were basically random and amorphous. However, two T(g)'s (glass transition temperatures) were observed in dynamic mechanical thermal analysis and also in differential scanning calorimetry thermograms. Furthermore, microdomains (about 17 nm in size) were indicated on the small-angle X-ray scattering profile and finally confirmed by transmission electron microscopy. Therefore, the PLCL copolymer was probably composed of a soft matrix of mainly epsilon-caprolactone moieties and hard domains containing more L-lactide units to exhibit a rubberlike elasticity in virtue of the physically cross-linked structure. The smooth muscle cells seeded scaffolds were implanted into nude mice subcutaneously for up to 15 weeks to monitor the in vivo degradation. In addition, they were degraded in vitro in phosphate buffer solution (pH 7.4) for up to 1 year to compare the results each other. All the scaffolds degraded slowly in vivo and in vitro even in the form of a highly porous thin membrane. However, the degradation rate was somewhat faster for in vivo than for in vitro. This should be explained by enzymes that might have played a certain role in the degradation in the body. In addition, the epsilon-caprolactone moieties degraded faster than the L-lactide units did in these PLCL scaffolds, although their hydrophilicities are in the opposite order. This behavior appeared more prominently in the in vivo case. This should result from that the amorphous regions composed of mainly epsilon-caprolactone units might have been first attacked by water because water can penetrate into the amorphous regions easier than the hard domains containing more L-lactides.     

Molecular characterization of NbCHMP1 encoding a homolog of human CHMP1 in Nicotiana benthamiana

In humans, CHMP1 encodes a protein of dual function that plays a role in both modification of chromatin structure and endosomal vesicle trafficking. Recently, it was found that sal1, a CHMP1 homolog in maize, is important for the development of the aleurone cell layers in maize endosperm. In this study, we investigated the structure and function of a Nicotiana benthamiana CHMP1 homolog designated NbCHMP1. NbCHMP1 encodes a small protein with a bipartite nuclear localization signal at its N-terminus, and good homology with the corresponding genes from diverse plants and animals. NbCHMP1 mRNA was present at comparable levels in stems, roots, flowers, and leaves. A GFP fusion of the full length NbCHMP1 protein was localized to the cytosol in distinct structures, while a GFP fusion of its N-terminal 80 aa was targeted to the nucleus, suggesting dual-targeting of NbCHMP1 in plants. Overexpression of NbCHMP1 in yeast did not affect its growth and the expressed protein was present in the cytosol in particulate form. Virus-induced gene silencing of NbCHMP1 resulted in subtle alterations of leaf morphology and color, without significantly affecting plant viability or development. Thus the CHMP1 homolog apparently does not play an essential role in the development of the vegetative tissues of N. benthamiana, in contrast to the essential role of sail in formation of the aleurone cell layers during maize endosperm development.