Probing the roles of active site residues in the 3'-5' exonuclease of the Werner syndrome protein

Werner syndrome is a premature aging disease caused by mutations in the WS gene and a deficiency in the function of Werner protein (WRN). The lack of WRN results in a cellular phenotype of genomic instability. WRN belongs to the RecQ DNA helicase family, but unlike other RecQ family members it possesses a functional exonuclease domain. We determined the crystal structure of mWRNexo (residues 31-238) bound to Zn(2+) and the sulfate ion. Compared with the structure of human WRNexo (hWRNexo), notable conformational changes were observed in several active site residues in an H5-H6 loop and in helices H6 and H7 of mWRNexo, presumably because of the presence of sulfate, which mimics the phosphate of substrate DNA. In particular, the side chains of Lys(185) and Tyr(206) were reoriented toward the Zn(2+) ion, whereas the side chain of Arg(190) pointed away from the active site center. Mutational analysis of these conserved residues abolished WRN exonuclease activity, suggesting that these residues play a critical role in the WRNexo activity. Based on substrate modeling and mutational analyses, we propose a mechanism by which WRNexo becomes activated upon substrate DNA binding. We also describe the low resolution trimeric structure of mouse WRNexoL (mWRNexoL, residues 31-330), as elucidated by small angle x-ray scattering (SAXS) analyses.     

Little evidence of a road‐effect zone for nocturnal,flying insects

Roads and traffic may be contributing to global declines of insect populations. The ecological effects of roads often extend far into the surrounding habitat, over a distance known as the road‐effect zone. The quality of habitat in the road‐effect zone is generally degraded (e.g., due to edge effects, noise, light, and chemical pollution) and can be reflected in species presence, abundance, or demographic parameters. Road‐effect zones have been quantified for some vertebrate species but are yet to be quantified for insects. Investigating the road‐effect zone for insects will provide a better understanding of how roads impact ecosystems, which is particularly important given the role insects play as pollinators, predators, and prey for other species. We quantified the road‐effect zone for nocturnal flying insects along three major freeways in agricultural landscapes in southeast Australia. We collected insects using light traps at six points along 2‐km transects perpendicular to each highway (n = 17). We sorted the samples into order, and dried and weighed each order to obtain a measure of dry biomass. Using regression models within a Bayesian framework of inference, we estimated the change in biomass of each order with distance from the road, while accounting for environmental variables such as temperature, moon phase, and vegetation structure. The biomass of nine of the ten orders sampled did not change with distance from the freeway. Orthoptera (i.e., grasshoppers and crickets) was the only order whose biomass increased with distance from the freeway. From our findings, we suggest that the impacts of roads on insects are unlikely extending into the surrounding landscape over a distance of 2 km. Therefore, if there are impacts of roads on insects, these are more likely to be concentrated at the road itself, or on finer taxonomic scales such as family or genus level.     

Association of the K173R variant and haplotypes in the aldosterone synthase gene with essential hypertension

Aldosterone synthase plays an important role in determining the levels of aldosterone secretion. Polymorphisms of the aldosterone synthase gene (CYP11B2) are suggested to be associated with essential hypertension. In this study, we examined associations of CYP11B2 polymorphisms [?344T/C, K173R and intron 2 conversion (IC)] with Korean hypertensive patients. Three hundred and forty patients with hypertension and 515 healthy normotensive subjects were studied. CYP11B2 polymorphisms in the subjects were analyzed by polymerase chain reaction–restriction fragment length polymorphism techniques. Of the three polymorphisms studied, we observed a significant difference in the mutant genotype of K173R polymorphism between the hypertensive and normotensive groups (P = 0.03). Several haplotype frequencies composed of three polymorphisms were also associated with hypertension susceptibility. Association between the K173R polymorphism and values of BMI, HDL-cholesterol and WC was found in the hypertensive group. However, no associations of ?344T/C and IC polymorphisms were found with the risk of hypertension and clinical parameters. Based on these results, the K173R variant and haplotypes of the CYP11B2 gene might affect hypertension susceptibility.     

Tumor Phosphatidylinositol-3-Kinase Signaling and Development of Metastatic Disease in Locally Advanced Rectal Cancer

Background

Recognizing EGFR as key orchestrator of the metastatic process in colorectal cancer, but also the substantial heterogeneity of responses to anti-EGFR therapy, we examined the pattern of composite tumor kinase activities governed by EGFR-mediated signaling that might be implicated in development of metastatic disease.

Patients and Methods

Point mutations in KRAS, BRAF, and PIK3CA and ERBB2 amplification were determined in primary tumors from 63 patients with locally advanced rectal cancer scheduled for radical treatment. Using peptide arrays with tyrosine kinase substrates, ex vivo phosphopeptide profiles were generated from the same baseline tumor samples and correlated to metastasis-free survival.

Results

Unsupervised clustering analysis of the resulting phosphorylation of 102 array substrates defined two tumor classes, both consisting of cases with and without KRAS/BRAF mutations. The smaller cluster group of patients, with tumors generating high ex vivo phosphorylation of phosphatidylinositol-3-kinase-related substrates, had a particularly aggressive disease course, with almost a half of patients developing metastatic disease within one year of follow-up.

Conclusion

High phosphatidylinositol-3-kinase-mediated signaling activity of the primary tumor, rather than KRAS/BRAF mutation status, was identified as a hallmark of poor metastasis-free survival in patients with locally advanced rectal cancer undergoing radical treatment of the pelvic cavity.     

Prenatal diagnosis of partial trisomy 3q resulting from t(3;14) in a fetus with multiple anomalies including vermian hypoplasia

Context

Myostatin (MSTN) is a member of the TGF-β superfamily of signal transduction proteins, which plays an important role in muscular growth and lipid metabolism.

Objective

To study the association of myostatin gene polymorphisms with obesity in Chinese north Han human subjects.

Design

297 healthy and 606 over-weight/obesity Chinese north Han subjects were selected as healthy control group and overweight/obesity group, respectively. The methods of DNA Sequencing, Restriction Fragment Length Polymorphism (RFLP) and TaqMan® probe were used to screen myostatin gene SNPs and clarify genotype in every individual.

Results

Total 11 SNPs in MSTN gene were identified by DNA sequencing and three SNPs including rs35781413 (G/A), rs3791783 (A/G) and rs3791782 (A/G) were selected for further study in total 903 samples. The results showed that the frequency of AA genotype of rs3791783 A/G SNP was significantly higher (56.4% vs. 50.8%) and the frequency GG genotype was significantly lower (3.2% vs. 6.7%) in overweight/obese patients than in normal weight subjects. A logistic regression analysis under a recessive inheritance model (AA + AG vs.GG) demonstrated that the Odd ratio for AA + AG vs.GG were 1.985 (95% CI 1.078-3.643; P = 0.029). Among three genotypes of rs3791783, the subjects with AA genotype have much more higher body weight, BMI, waist circumference, TC, TG and LDL-C than those with GG genotype.

Conclusions

Our data firstly suggest that genetic variant rs3791783 A/G in myostatin gene are associated with obesity. The A allele carriers in rs3791783 SNP have an increased susceptibility to obesity compared with the G allele carriers. Participants with AA genotype in rs3791783 SNP site will have higher risk suffered from overweight or obesity than those with GG genotype.     

Proteolytic cleavage of extracellular α-synuclein by plasmin: implications for Parkinson disease

Parkinson disease (PD) is the second most common neurodegenerative disease characterized by a progressive dopaminergic neuronal loss in association with Lewy body inclusions. Gathering evidence indicates that α-synuclein (α-syn), a major component of the Lewy body, plays an important role in the pathogenesis of PD. Although α-syn is considered to be a cytoplasmic protein, it has been detected in extracellular biological fluids, including human cerebrospinal fluid and blood plasma of healthy and diseased individuals. In addition, a prion-like spread of α-syn aggregates has been recently proposed to contribute to the propagation of Lewy bodies throughout the nervous system during progression of PD, suggesting that the metabolism of extracellular α-syn might play a key role in the pathogenesis of PD. In the present study, we found that plasmin cleaved and degraded extracellular α-syn specifically in a dose- and time- dependent manner. Aggregated forms of α-syn as well as monomeric α-syn were also cleaved by plasmin. Plasmin cleaved mainly the N-terminal region of α-syn and also inhibited the translocation of extracellular α-syn into the neighboring cells in addition to the activation of microglia and astrocytes by extracellular α-syn. Further, extracellular α-syn regulated the plasmin system through up-regulation of plasminogen activator inhibitor-1 (PAI-1) expression. These findings help to understand the molecular mechanism of PD and develop new therapeutic targets for PD.     

Reemergence of the bedbug Cimex lectularius in Seoul, Korea

A healthy 30-yr-old woman carrying an insect that had been caught in her living room visited the International Clinic at Severance Hospital, Seoul, in December 2007. The insect she brought was identified to be a nymph of a bedbug, Cimex lectularius, and her skin rashes looked typical bedbug''s bites. Her apartment was investigated, and a dead body of a bedbug, cast skins, and hatched eggs were found in her rooms and neighbors'' rooms in the same building. She was living in that apartment in Seoul for 9 months since she had moved from New Jersey, USA. We assume that the bedbugs were introduced from abroad, since there had been no report on bedbugs in Seoul for more than 2 decades at least. This is a report of a reemergence of the common bedbug, C. lectularius in Seoul, Korea.