An NMR-based identification of a peptide fragment from the beta-subunit of a G-protein showing specific interactions with the GBB domain of the Ste20 kinase in budding yeast

In mitogen-activated protein kinase (MAPK) cascades of budding yeast, pheromone-induced mating signal is transmitted by interactions between the beta-subunit of a G-protein (G-beta) and the G-beta binding (GBB) domain of Ste20 kinase. Previously, mutational analyses of the beta-subunit of G-protein had identified two critical mutations which abrogate binding of the GBB domain of Ste20. In this work, we have identified, by use of NMR spectroscopy, a peptide fragment from the G-beta that shows specific interactions with the isolated GBB domain of Ste20. A model structure of the Ste20/G-beta complex reveals that the interface of the hetero-complex may be sustained by parallel orientation of two potentially interacting helical segments that are further stabilized by ionic, hydrogen bond, and helix macro-dipole interactions.     

Aspirin Use and Lung Cancer Risk: A Possible Relationship? Evidence from an Updated Meta-Analysis

Background and Purpose

Growing evidence has emerged and controversial results reported on possible relationship between aspirin use and lung cancer risk. We, therefore, conducted this updated and comprehensive meta-analysis to evaluate this issue, with focus on dose-risk and duration-risk relationships.

Methods

We searched electronic databases including PUBMED, EMBASE and Cochrane library to identify eligible studies. Relative risk (RR) and its 95% confidence interval (CI) were used for cohort studies, while odds ratio (OR) were employed for case-control studies. The random effects and fixed effects models were used for analyses.

Results

18 studies were identified including 19835 lung cancer cases, which were eligible for inclusion in the present meta-analysis. Pooled data from case-control studies showed a significant inverse association between regular aspirin use and lung cancer risk. But for cohort studies, insignificant association was detected with little evidence of heterogeneity (RR: 1.05, 95%CI: 0.95 – 1.16; I²: 10.3%, p value: 0.351). In case-control studies, standard aspirin use (>325mg) was related to lower lung cancer incidence, compared with low-dose aspirin use (75–100mg). A similar trend was observed in cohort studies. Besides, when analysis was restricted to long time regular aspirin use (>5 years), insignificant results were reported in both cohort and case-control studies. Finally, regular aspirin use might result in higher reduction of non-small cell lung cancer incidence among men.

Conclusions

Our findings do not support the protective effect of regular aspirin use on lung cancer risk. Long time aspirin use, sex, dose and type of lung cancer might alter the effect of aspirin use on lung cancer risk. More well-designed studies are needed to further clarify these associations.     

Synthesis and antibacterial activity of novel water-soluble nocathiacin analogs

Semi-synthetic water-soluble analogs were synthesized from nocathiacin I through the formation of a versatile intermediate nocathiacin amine 5, and subsequent transformation via reductive amination, acylation or urea formation. Several of the novel analogs displayed much improved aqueous solubility over 1, while retained antibacterial activity. Compound 15 and 16 from the amide series, demonstrated excellent in vitro and in vivo antibacterial activity.     

Hydrocortisone modulates the effect of estradiol on endothelial nitric oxide synthase expression in human endothelial cells.

The interaction between hydrocortisone and estradiol on the regulation of endothelial nitric oxide synthase (eNOS) expression was investigated in human umbilical vein endothelial cells (HUVECs). Following incubation in medium containing dextran-coated-charcoal-stripped serum (DCC-stripped medium) for 4 days, incubation of HUVECs with 0.1 nM estradiol for 24 hr in the absence of hydrocortisone increased levels of eNOS mRNA measured by ribonuclease protection assay above control (0 nM estradiol). 2 microM hydrocortisone applied for 24 hr preceding and during estradiol application inhibited the estradiol-elicited increase in eNOS mRNA levels, reducing mRNA levels from 134% +/- 14% of control to 85% +/- 5% of control. Significant (ANOVA, p<0.01) reductions of estradiol-mediated increases of mRNA levels occurred over a range of hydrocortisone concentrations (10 nM, p<0.05; 2 microM, p<0.05; n=3-12). In the presence of 2 microM hydrocortisone, 10 nM estradiol significantly reduced eNOS mRNA levels to 59% +/- 3% of control. The ability of hydrocortisone to block or reverse the estradiol-mediated increase in eNOS mRNA levels may provide a link between elevated hydrocortisone levels and decreased NO production, potentially contributing to the development of hypertension and cardiovascular disease in vivo and antagonizing cardioprotective effects of estrogens.     

3-(7-Azaindolyl)-4-arylmaleimides as potent, selective inhibitors of glycogen synthase kinase-3

A novel series of acyclic 3-(7-azaindolyl)-4-(aryl/heteroaryl)maleimides was synthesized and evaluated for activity against GSK-3beta and selectivity versus PKC-betaII, as well as a broad panel of protein kinases. Compounds 14 and 17c potently inhibited GSK-3beta (IC(50)=7 and 26 nM, respectively) and exhibited excellent selectivity over PKC-betaII (325 and >385-fold, respectively). Compound 17c was also highly selective against 68 other protein kinases. In a cell-based functional assay, both 14 and 17c effectively increased glycogen synthase activity by inhibiting GSK-3beta.     

Viral tegument proteins restrict cGAS-DNA phase separation to mediate immune evasion

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Sphingosine 1-phosphate rapidly increases endothelial barrier function independently of VE-cadherin but requires cell spreading and Rho kinase

Sphingosine 1-phosphate (S1P) rapidly increases endothelial barrier function and induces the assembly of the adherens junction proteins vascular endothelial (VE)-cadherin and catenins. Since VE-cadherin contributes to the stabilization of the endothelial barrier, we determined whether the rapid, barrier-enhancing activity of S1P requires VE-cadherin. Ca(2+)-dependent, homophilic VE-cadherin binding of endothelial cells, derived from human umbilical veins and grown as monolayers, was disrupted with EGTA, an antibody to the extracellular domain of VE-cadherin, or gene silencing of VE-cadherin with small interfering RNA. All three protocols caused a reduction in the immunofluorescent localization of VE-cadherin at intercellular junctions, the separation of adjacent cells, and a decrease in basal endothelial electrical resistance. In all three conditions, S1P rapidly increased endothelial electrical resistance. These findings demonstrate that S1P enhances the endothelial barrier independently of homophilic VE-cadherin binding. Junctional localization of VE-cadherin, however, was associated with the sustained activity of S1P. Imaging with phase-contrast and differential interference contrast optics revealed that S1P induced cell spreading and closure of intercellular gaps. Pretreatment with latrunculin B, an inhibitor of actin polymerization, or Y-27632, a Rho kinase inhibitor, attenuated cell spreading and the rapid increase in electrical resistance induced by S1P. We conclude that S1P rapidly closes intercellular gaps, resulting in an increased electrical resistance across endothelial cell monolayers, via cell spreading and Rho kinase and independently of VE-cadherin.     

Studies on Karyotypes of 5 Species in Ranunculus from Jiangxi

The present paper reports the chromosome numbers and karyotypes of 5 species in Ranunculus from Jiangxi. The result is shown in Table 1-2. The chromosome numbers of R. ternatus Thunb. (2n=4x=32; 2n=2x=16=8m+2sm+6st) , R. polii Franch. (2n = 2x = 16 = 8m+2sm+6st) and R. sieboldii Miq. (2n = 8x-1 = 63 = 15m+18sm+22st+8t) are first reported. The essential points are as follows: (1) The karyotypes of R. ternatus Thunb. and R. polii Franch. are rather similar, which shows a close relationship between the two species. (2) Polyploid complexes are common in Ranunculus. (3) According to the taxonomical system of Wang Wen-cai, the karyotypes of the two species investigated in Sect. Auricomus belong to “2A” of Stebbins; that of the only species in Sect. Hecatonia belong to “2B'; the karyotypes of the two species investigated in Sect. Ranunculus belong to “3A” or “3B”. The relationships among the three sections from thekaryotype are basically consistent with those based on morphology.