siRNA screen of the human signaling proteome identifies the PtdIns(3,4,5)P<Subscript>3</Subscript>-mTOR signaling pathway as a primary regulator of transferrin uptake

Background  

Iron uptake via endocytosis of iron-transferrin-transferrin receptor complexes is a rate-limiting step for cell growth, viability and proliferation in tumor cells as well as non-transformed cells such as activated lymphocytes. Signaling pathways that regulate transferrin uptake have not yet been identified.     

Enhancement of clavulanic acid by replicative and integrative expression of ccaR and cas2 in Streptomyces clavuligerus NRRL3585

Clavulanic acid (CA) is an inhibitor of beta-lactamase that is produced from Streptomyces clavuligerus NRRL3585 and is used in combination with other antibiotics in clinical treatments. In order to increase the production of CA, the replicative and integrative expressions of ccaR (encoding for a specific regulator of the CA biosynthetic operon) and cas2 (encoding for the rate-limiting enzyme in the CA biosynthetic pathway) were applied. Six recombinant plasmids were designed for this study. The pIBRHL1, pIBRHL3, and pIBRHL13 were constructed for overexpression, whereas pNQ3, pNQ2, and pNQ1 were constructed for chromosomal integration with ccaR, cas2, and ccaR-cas2, respectively. All of these plasmids were transformed into S. clavuligerus NRRL3585. CA production in transformants resulted in a significantly enhanced amount greater than that of the wild type, a 2.25-fold increase with pIBRHL1, a 9.28-fold increase with pNQ3, a 5.06-fold increase with pIBRHL3, a 2.93-fold increase with pNQ2 integration, a 5.79-fold increase with pIBRHL13, and a 23.8-fold increase with pNQ1. The integrative pNQ1 strain has been successfully applied to enhance production.     

IL-1B-511 C-->T polymorphism is associated with increased host susceptibility to Helicobacter pylori infection in Chinese

BACKGROUND: The heritability of Helicobacter pylori infection from twin studies has been reported to be 0.66. However, few data were available on the host susceptibility to H. pylori infection in Chinese. We aimed to evaluate the impact of the IL-1B and IL-1RN single-nucleotide polymorphisms (SNP) and ABO blood types on the host susceptibility to H. pylori infection. METHODS: Individuals who underwent routine health check-up were enrolled. Genotyping was assessed by polymerase chain reaction (PCR) followed by direct sequencing and size fractionation using DNA from peripheral blood samples. Odds ratios (OR) for the susceptibility of H. pylori infection were computed from logistic regression models. RESULTS: The overall prevalence of H. pylori was 62% among the 663 healthy individuals, with 54.7, 63.5, and 66.9% in persons genotyped C/C, C/T, and T/T at IL-1B-511, respectively. Age (OR 1.05, 95% CI = 1.03-1.07, p < .001) and T carrier at IL-1B-511 (OR = 1.56, 95% CI = 1.06-2.30, p = .026) were independent factors associated with increased risks of H. pylori infection in the multivariate analysis. The risks of H. pylori infection were not related to IL-1RN SNP and ABO blood types. CONCLUSIONS: These findings support that a proinflammatory polymorphism at IL-1B promoter gene is associated with increased host susceptibility to H. pylori infection in Chinese.     

Prostacyclin inhibits endothelial cell XIAP ubiquitination and degradation

To understand the role of prostacyclin (PGI(2)) in protecting endothelial cells from apoptosis, we evaluated the effects of carbaprostacyclin (cPGI(2)) on H(2)O(2)-induced human umbilical vein endothelial cell (HUVEC) apoptosis. cPGI(2) suppressed H(2)O(2)-induced annexin V-positive cells in a concentration- and time-dependent manner. Pre-treatment of HUVEC with 50 microM cPGI(2) for 4 h produced the maximal anti-apoptotic effect. Authentic PGI(2) generated by adenoviral transfer of PGI(2) synthetic genes exerted a similar protective effect. cPGI(2) inhibited Smac/DIABLO release from mitochondria, caspase 3 activation, focal adhesion protein degradation, and cell detachment. cPGI(2) selectively protected X-linked inhibitor of apoptosis protein (X-linked IAP, XIAP) from H(2)O(2)-induced ubiquitination, and preserved XIAP protein levels. PD-98059 but not H-89 abrogated the protective action of cPGI(2). cPGI(2) increased ERK phosphorylation which was blocked by PD-98059. HUVEC stably transfected with dominant negative Ras abrogated XIAP preservation by cPGI(2) while constitutive active Ras increased ERK phosphorylation and protected XIAP from degradation. Our results demonstrate for the first time that PGI(2) inhibits XIAP ubiquitination and degradation via the Ras/MEK-1/ERK signaling pathway. Preservation of XIAP proteins represents a key mechanism by which PGI(2) protects endothelial cells from oxidant-induced apoptosis.     

Numerical and experimental studies on pulsatile flow in aneurysms arising laterally from a curved parent vessel at various angles

Both numerical and experimental studies have been performed to characterize the fluid flow inside the lateral aneurysms arising from the curved parent vessels at various angles gamma. The implicit solver was based on the time-dependent Navier-Stokes equations of incompressible laminar flow. Solutions were generated by a cell-center finite-volume method that used second order upwind and second order center flux difference splitting for the convection and diffusion term, respectively. The second order Crank-Nicolson method was used in the time integration term while the SIMPLEC algorithm was adopted to handle the pressure-velocity coupling. Complementarily, the particle tracking velocimetry (PTV) was used to measure the velocity fields. The conditions selected were to simulate an internal carotid artery with a diameter of 5 mm by similarity rules. The values of gamma explored were 0 degrees, 45 degrees, 90 degrees, and 135 degrees. Pulsatile flow with Wormersley number 3.9 and Reynolds numbers varying from 350 to 850 was considered. The computed results are firstly verified by the PTV measured ones. Discussion of the results is in terms of pulsatile main and secondary velocity vector fields, inflow rates into the aneurysm, and the distributions of wall shear stress and static pressure. It is found that among the angles examined gamma=45( composite function) is the riskiest angle from a fluid dynamics point of view and the aneurysmal dome is at risk.     

The Genetic Structure of Phellinus noxius and Dissemination Pattern of Brown Root Rot Disease in Taiwan

Since the 1990s, brown root rot caused by Phellinus noxius (Corner) Cunningham has become a major tree disease in Taiwan. This fungal pathogen can infect more than 200 hardwood and softwood tree species, causing gradual to fast decline of the trees. For effective control, we must determine how the pathogen is disseminated and how the new infection center of brown root rot is established. We performed Illumina sequencing and de novo assembly of a single basidiospore isolate Daxi42 and obtained a draft genome of ~40 Mb. By comparing the 12,217 simple sequence repeat (SSR) regions in Daxi42 with the low-coverage Illumina sequencing data for four additional P. noxius isolates, we identified 154 SSR regions with potential polymorphisms. A set of 13 polymorphic SSR markers were then developed and used to analyze 329 P. noxius isolates collected from 73 tree species from urban/agricultural areas in 14 cities/counties all around Taiwan from 1989 to 2012. The results revealed a high proportion (~98%) of distinct multilocus genotypes (MLGs) and that none of the 329 isolates were genome-wide homozygous, which supports a possible predominant outcrossing reproductive mode in P. noxius. The diverse MLGs exist as discrete patches, so brown root rot was most likely caused by multiple clones rather than a single predominant strain. The isolates collected from diseased trees near each other tend to have similar genotype(s), which indicates that P. noxius may spread to adjacent trees via root-to-root contact. Analyses based on Bayesian clustering, F _ST statistics, analysis of molecular variance, and isolation by distance all suggest a low degree of population differentiation and little to no barrier to gene flow throughout the P. noxius population in Taiwan. We discuss the involvement of basidiospore dispersal in disease dissemination.     

ICAM1 Is a Potential Cancer Stem Cell Marker of Esophageal Squamous Cell Carcinoma

Esophageal squamous cell carcinoma (ESCC) accounts for about 90% of esophageal cancer diagnosed in Asian countries, with its incidence on the rise. Cancer stem cell (CSC; also known as tumor-initiating cells, TIC) is inherently resistant to cytotoxic chemotherapy and radiation and associates with poor prognosis and therapy failure. Targeting therapy against cancer stem cell has emerged as a potential therapeutic approach to develop effective regimens. However, the suitable CSC marker of ESCC for identification and targeting is still limited. In this study, we screened the novel CSC membrane protein markers using two distinct stemness characteristics of cancer cell lines by a comparative approach. After the validation of RT-PCR, qPCR and western blot analyses, intercellular adhesion molecule 1 (ICAM1) was identified as a potential CSC marker of ESCC. ICAM1 promotes cancer cell migration, invasion as well as increasing mesenchymal marker expression and attenuating epithelial marker expression. In addition, ICAM1 contributes to CSC properties, including sphere formation, drug resistance, and tumorigenesis in mouse xenotransplantation model. Based on the analysis of ICAM1-regulated proteins, we speculated that ICAM1 regulates CSC properties partly through an ICAM1-PTTG1IP-p53-DNMT1 pathway. Moreover, we observed that ICAM1 and CD44 could have a compensation effect on maintaining the stemness characteristics of ESCC, suggesting that the combination of multi-targeting therapies should be under serious consideration to acquire a more potent therapeutic effect on CSC of ESCC.     

Increased expression of glucose transporter 3 in gerbil brains following magnesium sulfate treatment and focal cerebral ischemic injury

Glucose is the primary energy substrate for neurons. Glucose transporter 3 (Glut3) localizes at the neuronal cellular membrane, which transports glucose from the extracelluar space into neurons. Ischemia results in an increased energy demand that is associated with profound changes in brain energy metabolism. Magnesium sulfate (MgSO₄) ameliorates ischemia‐induced neuronal death in the rat and gerbil model. We investigated the effects of MgSO₄ administration on the expression of Glut3 in cortex and hippocampus of gerbils during ischemia. The focal cerebral ischemia was produced by unilateral occlusion of the right common carotid artery and right middle cerebral artery. Following ischemia, Glut3 expression increased significantly versus non‐ischemic (contra‐lateral) cortex and hippocampus. MgSO₄ treatment significantly increased the level of Glut3 expression in the non‐ischemic and ischemic cortex and hippocampus. We found that the MgSO₄‐induced increase in Glut3 expression was not reversed by administration of U0126, a MEK kinase inhibitor. These results suggest that other factors may function to modulate the MgSO₄‐induced Glut3 response. In all, our data showed that MgSO₄ increases the expression of Glut3 in the cortex and hippocampus of gerbil brains both in non‐ischemia and ischemia status. However, the MEK signaling pathway might not be involved in MgSO₄‐induced Glut3 expression following focal ischemia. Copyright © 2010 John Wiley & Sons, Ltd.     

桔梗生物学的研究

桔梗既是一种资源植物;又为常用中药,可宣肺祛痰、利咽排脓;并供作菜肴,别具风味,颇受欢迎。不论药用或食用,多年来皆依靠采挖野生资源。近年来,由于荒原减少,再加上只采不育,野生资源日益枯竭,既使过去每年调出量很大的黑龙江省亦感紧缺!为此,我们自1981年以来,对桔梗的生物学进行了一些研究,希望对保护和发展这一资源,乃至引种栽培提供理论依据。