Structural Basis of the Novel S. pneumoniae Virulence Factor,GHIP, a Glycosyl Hydrolase 25 Participating in Host-Cell Invasion

Pathogenic bacteria produce a wide variety of virulence factors that are considered to be potential antibiotic targets. In this study, we report the crystal structure of a novel S. pneumoniae virulence factor, GHIP, which is a streptococcus-specific glycosyl hydrolase. This novel structure exhibits an α/β-barrel fold that slightly differs from other characterized hydrolases. The GHIP active site, located at the negatively charged groove in the barrel, is very similar to the active site in known peptidoglycan hydrolases. Functionally, GHIP exhibited weak enzymatic activity to hydrolyze the PNP-(GlcNAc)₅ peptidoglycan by the general acid/base catalytic mechanism. Animal experiments demonstrated a marked attenuation of S. pneumoniae-mediated virulence in mice infected by ΔGHIP-deficient strains, suggesting that GHIP functions as a novel S. pneumoniae virulence factor. Furthermore, GHIP participates in allowing S. pneumoniae to colonize the nasopharynx and invade host epithelial cells. Taken together, these findings suggest that GHIP can potentially serve as an antibiotic target to effectively treat streptococcus-mediated infection.     

Contributory Role of Five Common Polymorphisms of RAGE and APE1 Genes in Lung Cancer among Han Chinese

Background

Lung cancer is the leading cause of cancer mortality in China. Given the ubiquitous nature of gene-to-gene interaction in lung carcinogenesis, we sought to evaluate five common polymorphisms from advanced glycosylation end product-specific receptor (RAGE) and apurinic/apyrimidinic endonuclease 1 (APE1) genes in association with lung cancer among Han Chinese.

Methods and Results

819 patients with lung cancer and 803 cancer-free controls were recruited from Qiqihar city. Genotypes of five examined polymorphisms (RAGE gene: rs1800625, rs1800624, rs2070600; APE1 gene: rs1760944, rs1130409) were determined by ligase detection reaction method. Data were analyzed by R software and multifactor dimensionality reduction (MDR). Hardy-Weinberg equilibrium was satisfied for all five polymorphisms. Overall differences in the genotype and allele distributions were significant for rs1800625 (P_genotype<0.0005; P_allele<0.0005), rs2070600 (P_genotype = 0.005; P_allele = 0.004) and rs1130409 (P_genotype = 0.009; P_allele = 0.004) polymorphisms. Haplotype C-A-A (alleles in order of rs1800625, rs1800624 and rs2070600) of RAGE gene was overrepresented in patients, and conferred a 2.1-fold increased risk of lung cancer (95% confidence interval: 1.52–2.91), independent of confounding factors. Further application of MDR method to five examined polymorphisms identified the overall best interaction model including rs2070600 and rs1130409 polymorphisms. This model had a maximal testing accuracy of 64.63% and a maximal cross-validation consistency of 9 out of 10 at the significant level of 0.006.

Conclusions

Our findings demonstrated a potential interactive contribution of RAGE and APE1 genes to the pathogenesis of lung cancer among Han Chinese. Further studies are warranted to confirm or refute these findings.     

Correlation of Epididymal Protease Inhibitor and Fibronectin in Human Semen

Objective

Epididymal protease inhibitor (Eppin) was located on the surface of spermatozoa and modulates the liquefaction of human semen. Here, we identify the correlative protein partner of Eppin to explore the molecular mechanism of liquefaction of human semen.

Methods

(1) Human seminal vesicle proteins were transferred on the membrane by Western blotting and separated by 2-D electrophoresis and incubated in recombinant Eppin. The correlative protein was identified by Mass Spectrometry (MS) (2). Western blotting was used to determine the relation of rEppin and rFibronectin(Fn); (3) Co-localization in spermatozoa were detected using immunofluorescence; (4) Correalation of Eppin and Fn was proved by co-immunoprecipitation.

Results

Fn was identified as the binding partner of recombinant Eppin by MS. Recombinant of Eppin was made and demonstrated that the Eppin fragment binds the fn 607-1265 fragment. The Eppin-Fn complex presents on the sperm tail and particularly in the midpiece region of human ejaculated spermatozoa. Immunoprecipitation indicated that Eppin in the spermatozoa lysates was complexed with Fn.

Conclusions

Our study demonstrates that Eppin and Fn bind to each other in human semen and on human ejaculated spermatozoa. Eppin-Fn complex may involve in semen coagulation, liquefaction and the survival and preparation of spermatozoa for fertility in the female reproductive tract.     

Association of Four Genetic Polymorphisms of AGER and Its Circulating Forms with Coronary Artery Disease: A Meta-Analysis

Background

Considerable efforts have been devoted to evaluating the association of the receptor for advanced glycation end-products (gene AGER and protein: RAGE) genetic variants to coronary artery disease (CAD); the results, however, are often irreproducible. To generate more information, we sought to explore four common polymorphisms of AGER and its circulating forms associated with the risk of CAD via a meta-analysis.

Methodology/Principal Findings

Articles were identified by searching PubMed, EMBASE, Wanfang and CNKI databases before March 2013. Qualified articles had case-control designs and investigated AGER four polymorphisms (T-429C, T-374A, Gly82Ser, G1704A) or circulating soluble RAGE (sRAGE) or endogenous secretory RAGE (esRAGE) levels associated with CAD. Twenty-seven articles involving 39 independent groups fulfilled the predefined criteria. Overall, no significance was observed for all examined polymorphisms under allelic and dominant models. When restricting groups to CAD patients with diabetes mellitus or renal disease, deviations of risk estimates from the unity were stronger than overall estimates for all polymorphisms except for G1704A due to limited available studies. For example, under dominant model, having -429C allele increased the odds of developing CAD in diabetic patients by 1.22-fold (95% confidence interval (95% CI) 0.99–1.51; P = 0.06; I ² = 6.7%) compared with that of overall estimate of 1.15-fold (95% CI: 0.97–1.36; P = 0.111; I ² = 18.0%). Circulating sRAGE levels were non-significantly lower in CAD patients than in controls, whereas this reduction was totally and significantly reversed in CAD patients with diabetes mellitus (weighted mean difference: 185.71 pg/ml; 95% CI: 106.82 to 264.61 pg/ml). Circulating esRAGE levels were remarkably lower in CAD patients, as well as in subgroups with or without diabetes mellitus and without renal disease.

Conclusions

Our findings demonstrated that association of AGER genetic polymorphisms with CAD was potentiated in patients with diabetes mellitus or renal disease. Practically, circulating esRAGE might be a powerful negative predictor for the development of CAD.     

The Role of Metal Components in the Cardiovascular Effects of PM2.5

Exposure to ambient fine particulate matter (PM_2.5) increases risks for cardiovascular disorders (CVD). However, the mechanisms and components responsible for the effects are poorly understood. Based on our previous murine exposure studies, a translational pilot study was conducted in female residents of Jinchang and Zhangye, China, to test the hypothesis that specific chemical component of PM_2.5 is responsible for PM_2.5 associated CVD. Daily ambient and personal exposures to PM_2.5 and 35 elements were measured in the two cities. A total of 60 healthy nonsmoking adult women residents were recruited for measurements of inflammation biomarkers. In addition, circulating endothelial progenitor cells (CEPCs) were also measured in 20 subjects. The ambient levels of PM_2.5 were comparable between Jinchang and Zhangye (47.4 and 54.5µg/m³, respectively). However, the levels of nickel, copper, arsenic, and selenium in Jinchang were 82, 26, 12, and 6 fold higher than Zhangye, respectively. The levels of C-reactive protein (3.44±3.46 vs. 1.55±1.13), interleukin-6 (1.65±1.17 vs. 1.09±0.60), and vascular endothelial growth factor (117.6±217.0 vs. 22.7±21.3) were significantly higher in Jinchang. Furthermore, all phenotypes of CEPCs were significantly lower in subjects recruited from Jinchang than those from Zhangye. These results suggest that specific metals may be important components responsible for PM_2.5-induced cardiovascular effects and that the reduced capacity of endothelial repair may play a critical role.