Structural characterization of a carbon monoxide adduct of a heme–DNA complex

Abstract  

The structure of a carbon monoxide (CO) adduct of a complex between heme and a parallel G-quadruplex DNA formed from a single repeat sequence of the human telomere, d(TTAGGG), has been characterized using ¹H and ¹³C NMR spectroscopy and density function theory calculations. The study revealed that the heme binds to the 3′-terminal G-quartet of the DNA though a π–π stacking interaction between the porphyrin moiety of the heme and the G-quartet. The π–π stacking interaction between the pseudo-C ₂-symmetric heme and the C ₄-symmetric G-quartet in the complex resulted in the formation of two isomers possessing heme orientations differing by 180° rotation about the pseudo-C ₂ axis with respect to the DNA. These two slowly interconverting heme orientational isomers were formed in a ratio of approximately 1:1, reflecting that their thermodynamic stabilities are identical. Exogenous CO is coordinated to heme Fe on the side of the heme opposite the G-quartet in the complex, and the nature of the Fe–CO bond in the complex is similar to that of the Fe–CO bonds in hemoproteins. These findings provide novel insights for the design of novel DNA enzymes possessing metalloporphyrins as prosthetic groups.     

Discovery of S-777469: an orally available CB2 agonist as an antipruritic agent

The discovery of novel CB2 ligands based on the 3-carbamoyl-2-pyridone derivatives by adjusting the size of side chain at 1-, 5- and 6-position is reported. The structure-activity relationship around this template lead to the identification of S-777469 as a selective CB2 receptor agonist, which exhibited the significant inhibition of scratching induced by Compound 48/80 at 1.0 mg/kg po and 10 mg/kg po (55% and 61%, respectively).     

Design and synthesis of novel macrocyclic 2-amino-6-arylpyrimidine Hsp90 inhibitors

Macrocyclic compounds bearing a 2-amino-6-arylpyrimidine moiety were identified as potent heat shock protein 90 (Hsp90) inhibitors by modification of 2-amino-6-aryltriazine derivative (CH5015765). We employed a macrocyclic structure as a skeleton of new inhibitors to mimic the geldanamycin-Hsp90 interactions. Among the identified inhibitors, CH5164840 showed high binding affinity for N-terminal Hsp90α (K(d)=0.52nM) and strong anti-proliferative activity against human cancer cell lines (HCT116 IC(50)=0.15μM, NCI-N87 IC(50)=0.066μM). CH5164840 displayed high oral bioavailability in mice (F=70.8%) and potent antitumor efficacy in a HCT116 human colorectal cancer xenograft model (tumor growth inhibition=83%).     

CXCL14 enhances insulin-dependent glucose uptake in adipocytes and is related to high-fat diet-induced obesity

Accumulating evidence suggests an association between obesity and adipose tissue inflammation. Chemokines are involved in the regulation of inflammation status. Chemokine (C-X-C motif) ligand 14 (CXCL14) is known to be a chemoattractant for monocyte and dendritic cells. Recently, it was reported that CXCL14-deficient mice show resistance to high-fat diet-induced obesity. In this study, we identified CXCL14 as a growth hormone (GH)-induced gene in HepG2 hepatoma cells. Substantial in vivo expression of CXCL14 was detected in the adipose tissue and liver. Its expression and secretion were strikingly increased by insulin administration and high-fat diet. Intriguingly, incubation of 3T3-L1 adipocytes with CXCL14 stimulated insulin-dependent glucose uptake. Further, this effect was associated with enhanced insulin signaling. CXCL14 enhanced the insulin-induced tyrosine phosphorylation of insulin receptors and insulin receptor substrate-1. These results suggest that CXCL14 plays a causal role in high-fat diet-induced obesity.     

Bioconversion of ferulic acid to 4-vinylguaiacol and 4-ethylguaiacol and of 4-vinylguaiacol to 4-ethylguaiacol by halotolerant yeasts belonging to the genus Candida

In order to examine the genesis of the characteristic flavors of soy sauce and miso, seven novel halotolerant yeast strains of two types, which showed convertibility of ferulic acid (FA) to 4-vinylguaiacol (4-VG) and to 4-ethylguaiacol (4-EG), were isolated from miso-koji and miso pastes. Two of these strains were identified as Candida guilliermondii (anamorph of Pichia guilliermondii), and Candida fermentati (anamorph of Pichia caribbica), based on sequence analyses of a partial 26S ribosomal RNA gene and the region of internal transcribed spacers 1 and 2, and the 5.8S ribosomal RNA gene. Moreover, we also found three Candida etchellsii strains which showed convertibility of FA to 4-VG, but not to 4-EG, and two atypical strains of Candida versatilis which showed no convertibility of FA to 4-VG, but did show convertibility of 4-VG to 4-EG from soy sauce mashes. The bioconversion pathway from FA to 4-EG via 4-VG in halotolerant yeasts and bacteria is discussed.     

Development of a loop-mediated isothermal amplification (LAMP) method for specific detection of Mycobacterium bovis

Bovine tuberculosis (TB) caused by Mycobacterium bovis is a significant health threat to cattle and a zoonotic threat for humans in many developing countries. Rapid and accurate detection of M. bovis is fundamental for controlling the disease in animals and humans, and for the proper treatment of patients as one of the first-line anti-TB drug, pyrazinamide, is ineffective against M. bovis. Currently, there are no rapid, simplified and low-cost diagnostic methods that can be easily integrated for use in many developing countries. Here, we report the development of a loop-mediated isothermal amplification (LAMP) assay for specific identification of M. bovis by targeting the region of difference 4 (RD4), a 12.7 kb genomic region that is deleted solely in M. bovis. The assay''s specificity was evaluated using 139 isolates comprising 65 M. bovis isolates, 40 M. tuberculosis isolates, seven M. tuberculosis complex reference strains, 22 non-tuberculous mycobacteria and five other bacteria. The established LAMP detected only M. bovis isolates as positive and no false positives were observed using the other mycobacteria and non-mycobacteria tested. Our LAMP assay detected as low as 10 copies of M. bovis genomic DNA within 40 minutes. The procedure of LAMP is simple with an incubation at a constant temperature. Results are observed with the naked eye by a color change, and there is no need for expensive equipment. The established LAMP can be used for the detection of M. bovis infections in cattle and humans in resource-limited areas.     

Surfactant protein D attenuates sub-epithelial fibrosis in allergic airways disease through TGF-β

Background

Surfactant protein D (SP-D) can regulate both innate and adaptive immunity. Recently, SP-D has been shown to contribute to the pathogenesis of airway allergic inflammation and bleomycin-induced pulmonary fibrosis. However, in allergic airways disease, the role of SP-D in airway remodeling remains unknown. The objective of this study was to determine the contribution of functional SP-D in regulating sub-epithelial fibrosis in a mouse chronic house dust mite model of allergic airways disease.

Methods

C57BL/6 wild-type (WT) and SP-D−/− mice (C57BL/6 background) were chronically challenged with house dust mite antigen (Dermatophagoides pteronyssinus, Dp). Studies with SP-D rescue and neutralization of TGF-β were conducted. Lung histopathology and the concentrations of collagen, growth factors, and cytokines present in the airspace and lung tissue were determined. Cultured eosinophils were stimulated by Dp in presence or absence of SP-D.

Results

Dp-challenged SP-D−/− mice demonstrate increased sub-epithelial fibrosis, collagen production, eosinophil infiltration, TGF-β1, and IL-13 production, when compared to Dp-challenged WT mice. By immunohistology, we detected an increase in TGF-β1 and IL-13 positive eosinophils in SP-D−/− mice. Purified eosinophils stimulated with Dp produced TGF-β1 and IL-13, which was prevented by co-incubation with SP-D. Additionally, treatment of Dp challenged SP-D−/− mice with exogenous SP-D was able to rescue the phenotypes observed in SP-D−/− mice and neutralization of TGF-β1 reduced sub-epithelial fibrosis in Dp-challenged SP-D−/− mice.

Conclusion

These data support a protective role for SP-D in the pathogenesis of sub-epithelial fibrosis in a mouse model of allergic inflammation through regulation of eosinophil-derived TGF-β.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-014-0143-9) contains supplementary material, which is available to authorized users.     

Protective Efficacy of Passive Immunization with Monoclonal Antibodies in Animal Models of H5N1 Highly Pathogenic Avian Influenza Virus Infection

Highly pathogenic avian influenza (HPAI) viruses of the H5N1 subtype often cause severe pneumonia and multiple organ failure in humans, with reported case fatality rates of more than 60%. To develop a clinical antibody therapy, we generated a human-mouse chimeric monoclonal antibody (MAb) ch61 that showed strong neutralizing activity against H5N1 HPAI viruses isolated from humans and evaluated its protective potential in mouse and nonhuman primate models of H5N1 HPAI virus infections. Passive immunization with MAb ch61 one day before or after challenge with a lethal dose of the virus completely protected mice, and partial protection was achieved when mice were treated 3 days after the challenge. In a cynomolgus macaque model, reduced viral loads and partial protection against lethal infection were observed in macaques treated with MAb ch61 intravenously one and three days after challenge. Protective effects were also noted in macaques under immunosuppression. Though mutant viruses escaping from neutralization by MAb ch61 were recovered from macaques treated with this MAb alone, combined treatment with MAb ch61 and peramivir reduced the emergence of escape mutants. Our results indicate that antibody therapy might be beneficial in reducing viral loads and delaying disease progression during H5N1 HPAI virus infection in clinical cases and combined treatment with other antiviral compounds should improve the protective effects of antibody therapy against H5N1 HPAI virus infection.