Identification and Expression of the Genes Encoding a Reactivating Factor for Adenosylcobalamin-Dependent Glycerol Dehydratase

Adenosylcobalamin-dependent glycerol dehydratase undergoes inactivation by glycerol, the physiological substrate, during catalysis. In permeabilized cells of Klebsiella pneumoniae, the inactivated enzyme is reactivated in the presence of ATP, Mg2+, and adenosylcobalamin. We identified the two open reading frames as the genes for a reactivating factor for glycerol dehydratase and designated them gdrA and gdrB. The reactivation of the inactivated glycerol dehydratase by the gene products was confirmed in permeabilized recombinant Escherichia coli cells coexpressing GdrA and GdrB proteins with glycerol dehydratase.     

Ultrahigh resolution drug design. II. Atomic resolution structures of human aldose reductase holoenzyme complexed with Fidarestat and Minalrestat: implications for the binding of cyclic imide inhibitors

The X-ray structures of human aldose reductase holoenzyme in complex with the inhibitors Fidarestat (SNK-860) and Minalrestat (WAY-509) were determined at atomic resolutions of 0.92 A and 1.1 A, respectively. The hydantoin and succinimide moieties of the inhibitors interacted with the conserved anion-binding site located between the nicotinamide ring of the coenzyme and active site residues Tyr48, His110, and Trp111. Minalrestat's hydrophobic isoquinoline ring was bound in an adjacent pocket lined by residues Trp20, Phe122, and Trp219, with the bromo-fluorobenzyl group inside the "specificity" pocket. The interactions between Minalrestat's bromo-fluorobenzyl group and the enzyme include the stacking against the side-chain of Trp111 as well as hydrogen bonding distances with residues Leu300 and Thr113. The carbamoyl group in Fidarestat formed a hydrogen bond with the main-chain nitrogen atom of Leu300. The atomic resolution refinement allowed the positioning of hydrogen atoms and accurate determination of bond lengths of the inhibitors, coenzyme NADP+ and active-site residue His110. The 1'-position nitrogen atom in the hydantoin and succinimide moieties of Fidarestat and Minalrestat, respectively, form a hydrogen bond with the Nepsilon2 atom of His 110. For Fidarestat, the electron density indicated two possible positions for the H-atom in this bond. Furthermore, both native and anomalous difference maps indicated the replacement of a water molecule linked to His110 by a Cl-ion. These observations suggest a mechanism in which Fidarestat is bound protonated and becomes negatively charged by donating the proton to His110, which may have important implications on drug design.     

Characterization of autoantigens relevant to autoimmune ophthalmitis and thyroiditis in mice immunized with the syngeneic tissue extracts and Klebsiella O3 lipopolysaccharide

The histological localization and biochemical properties of the autoantigens relevant to experimental autoimmune ophthalmitis and thyroiditis were studied using sera from mice hyperimmunized with the corresponding tissue extract of syngeneic mice and Klebsiella O3 lipopolysaccharide (KO3 LPS) as a potent adjuvant. Specific antigens were detected in the lens of the eyeball by immunofluorescence test with sera from mice in which ophthalmitis had been induced and the antigens were lenticular proteins with molecular weights (MW) of 15,000 (15K) to 25K, and 45K. The lenticular proteins with MW of 15K to 25K correspond to the subunits of crystalline. These findings clearly demonstrated that our experimental model for autoimmune ophthalmitis was classified as the lens-induced uveitis. The colloids of the thyroid follicles and the follicular cells were markedly stained by sera from mice in which thyroiditis had been induced. One of the autoantigens detected in the thyroid gland was biochemically consistent with a thyroglobulin subunit. It was also shown that these autoantigens detected in the present study were organ-specific but not species-specific. The nature of autoantigens in the eye and the thyroid gland is discussed.     

In vivo sequence variability of human immunodeficiency virus type 1 envelope gp120: association of V2 extension with slow disease progression.

According to the rate of depletion of CD4 cell counts, we grouped 12 cases of human immunodeficiency virus type 1 (HIV-1) infection as 6 rapid (21.0 to 33.8 cells per microl per month) and 6 slow (0.9 to 7.9 cells per microl per month) progressors and determined the individual viral quasispecies patterns by sequencing the genome region encoding the V1, V2, and V3 loops of envelope protein. Although the quasispecies structures varied widely from one individual to another, a strong correlation was observed between a low rate of disease progression and a high degree of genetic diversity of HIV-1. Furthermore, the V2 loop extension was observed specifically in individuals with slow or no disease progression, whereas basic amino acid substitutions in V3 characteristic of a viral phenotype shift from non-syncytium inducing to syncytium inducing were observed in patients with advanced stages of disease regardless of their rate of disease progression. Studies with recombinant viruses suggested that elongation of V2 potentially restricts the capacity of HIV-1 to replicate in macrophages. Thus, our results suggest the association of distinct sequence features of both V3 and V2 with particular patterns of disease progression. Elongation of the V2 loop may be a good predictor of slow disease progression, while basic substitutions of V3 without elongation of V2 are characteristic of rapid progression.     

Acute exercise increases expression of extracellular superoxide dismutase in skeletal muscle and the aorta

Exercise dramatically increases oxygen consumption and causes oxidative stress. Superoxide dismutase (SOD) is important in the first-line defence mechanisms against oxidative stress. To investigate the effect of acute exercise on the expression of SOD, we examined the expression of mRNA for three SOD isozymes, in mice run on a treadmill to exhaustion. Six hours after exercise, the expression of extracellular SOD (EC-SOD) mRNA increased significantly in skeletal muscle and persisted for 24 h, whereas no change was observed for cytoplasmic and mitochondrial SOD mRNA. Moreover, acute exercise also induced EC-SOD mRNA in the aorta. These results suggest that a single bout of exercise is enough to augment the expression EC-SOD mRNA in skeletal muscle and the aorta, and may partly explain the beneficial effect of exercise.     

Contribution of maternal mRNA for maintenance of Ca2+-dependent reaggregating activity in dissociated cells of Xenopus laevis embryos

Dissociated Xenopus laevis blastula cells, where reaggregation was inhibited in Ca2+-free medium, reaggregated immediately after the addition of Ca2+. This reaggregation was not inhibited by cordycepin or actinomycin D treatment during culture, although cycloheximide and puromycin were inhibitory. The reaggregation was not inhibited even when fertilized eggs were microinjected with cordycepin and their RNA synthesis was continuously inhibited through cleavage to blastula stages. In neurula cells, cordycepin treatment induced significant reduction in sizes of aggregates formed. These results suggest that the Ca2+-dependent reaggregating activity of blastula cells is maintained by the translation of maternal, rather than newly synthesized, mRNA.     

Genistein Suppresses Prostate Cancer Growth through Inhibition of Oncogenic MicroRNA-151

Genistein has been shown to suppress the growth of several cancers through modulation of various pathways. However, the effects of genistein on the regulation of oncogenic microRNA-151 (miR-151) have not been reported. In this study, we investigated whether genistein could alter the expression of oncogenic miR-151 and its target genes that are involved in the progression and metastasis of prostate cancer (PCa). Real-time RT-PCR showed that the expression of miR-151 was higher in PC3 and DU145 cells compared with RWPE-1 cells. Treatment of PC3 and DU145 cells with 25 μM genistein down-regulated the expression of miR-151 compared with vehicle control. Inhibition of miR-151 in PCa cells by genistein significantly inhibited cell migration and invasion. In-silico analysis showed that several genes (CASZ1, IL1RAPL1, SOX17, N4BP1 and ARHGDIA) suggested to have tumor suppressive functions were target genes of miR-151. Luciferase reporter assays indicated that miR-151 directly binds to specific sites on the 3'UTR of target genes. Quantitative real-time PCR analysis showed that the mRNA expression levels of the five target genes in PC3 and DU145 were markedly changed with miR-151 mimics and inhibitor. Kaplan-Meier curves and log-rank tests revealed that high expression levels of miR-151 had an adverse effect on survival rate. This study suggests that genistein mediated suppression of oncogenic miRNAs can be an important dietary therapeutic strategy for the treatment of PCa.     

Polymorphisms of interferon-inducible genes OAS-1 and MxA associated with SARS in the Vietnamese population

We hypothesized that host antiviral genes induced by type I interferons might affect the natural course of severe acute respiratory syndrome (SARS). We analyzed single nucleotide polymorphisms (SNPs) of 2',5'-oligoadenylate synthetase 1 (OAS-1), myxovirus resistance-A (MxA), and double-stranded RNA-dependent protein kinase in 44 Vietnamese SARS patients with 103 controls. The G-allele of non-synonymous A/G SNP in exon 3 of OAS-1 gene showed association with SARS (p=0.0090). The G-allele in exon 3 of OAS-1 and the one in exon 6 were in strong linkage disequilibrium and both of them were associated with SARS infection. The GG genotype and G-allele of G/T SNP at position -88 in the MxA gene promoter were found more frequently in hypoxemic group than in non-hypoxemic group of SARS (p=0.0195). Our findings suggest that polymorphisms of two IFN-inducible genes OAS-1 and MxA might affect susceptibility to the disease and progression of SARS at each level.     

Cloning of Clostridium perfringens alpha-toxin gene and extracellular expression in Escherichia coli]

Clostridium perfringens (C. perfringens) is a Gram-positive bacterial pathogen that widely propagets in the soil and the gastrointestinal tract of human and animals. This bacteria causes food poisoning, gas gangrene and other various range of infectious diseases. But there is no standard diagnosis method of C. perfringens. In order to develop a new type of immunoassay for clinical purpose, we studied expression and extracellular secretion of recombinant alpha-toxin having enzyme activity in E. coli expression system. Cloning was carried out after PCR amplification from C. perfringens GAI 94074 which was clinical isolate. Three kinds of fragment were cloned using pET100/D-TOPO vector. These fragments coded for ribosome binding site, signal peptide, and alpha-toxin gene respectively. Recombinant pET100 plasmid transformed into TOP 10 cells and the obtained plasmids were transformed into BL21 (DE3) cells. Then, the transformants were induced expression with IPTG. In conclusion, we successfully cloned, expressed and exteracellular secreted C. perfringens alpha-toxin containing signal peptide. Biologically, the obtained recombinant protein was positive for phospholipase C activity.