Egr-1 Activation by Cancer-Derived Extracellular Vesicles Promotes Endothelial Cell Migration via ERK1/2 and JNK Signaling Pathways

Various mammalian cells, including cancer cells, shed extracellular vesicles (EVs), also known as exosomes and microvesicles, into surrounding tissues. These EVs play roles in tumor growth and metastasis by promoting angiogenesis. However, the detailed mechanism of how cancer-derived EVs elicit endothelial cell activation remains unknown. Here, we provide evidence that early growth response-1 (Egr-1) activation in endothelial cells is involved in the angiogenic activity of colorectal cancer cell-derived EVs. Both RNA interference-mediated downregulation of Egr-1 and ERK1/2 or JNK inhibitor significantly blocked EV-mediated Egr-1 activation and endothelial cell migration. Furthermore, lipid raft-mediated endocytosis inhibitor effectively blocked endothelial Egr-1 activation and migration induced by cancer-derived EVs. Our results suggest that Egr-1 activation in endothelial cells may be a key mechanism involved in the angiogenic activity of cancer-derived EVs. These findings will improve our understanding regarding the proangiogenic activities of EVs in diverse pathological conditions including cancer, cardiovascular diseases, and neurodegenerative diseases.open11617sciescopu

Appointment waiting times and education level influence the quality of bowel preparation in adult patients undergoing colonoscopy

<p>Abstract</p> <p>Background</p> <p>Risk factors for poor bowel preparation are recognized to be independent of the type of bowel preparation method used. Patient and administrative factors influencing bowel preparation are known to vary in different healthcare systems.</p> <p>Methods</p> <p>A prospective, cross-sectional study of patients undergoing colonoscopy in an Asian tertiary centre was conducted to identify risk factors associated with poor bowel preparation, and to evaluate the impact of poor bowel preparation on technical performance and patient comfort.</p> <p>Results</p> <p>Data on 501 patients (mean age 60.1 ± 14.0 years old, 51.2% males, 60.9% with secondary education or higher) was available for analysis. Poor bowel preparation was present in 151 patients (30.1%). Lower education level (OR = 2.35, 95% CI = 1.54 - 3.60), colonoscopy appointment waiting time beyond 16 weeks (OR = 1.86, 95% CI = 1.04 - 3.37) and non-adherence to bowel preparation instructions (OR = 4.76, 95% CI = 3.00 - 7.55) were identified as independent risk factors for poor bowel preparation. Poor bowel preparation was associated with a lower cecal intubation rate (78.1% versus 98.3%, p < 0.001), prolonged total colonoscopy time (25.4 ± 12.6 minutes versus 16.7 ± 10.2 minutes, p < 0.001), and increased patient discomfort during colonoscopy (patient with moderate to severe abdominal discomfort 31.8% versus 3.2%, p < 0.001).</p> <p>Conclusions</p> <p>Education levels and appointment waiting times, in addition to non-adherence to bowel preparation instructions, increase the risk of poor bowel preparation in adult patients undergoing colonoscopy. The latter has a significant impact on colonoscopy performance and patient comfort.</p

What clinicians who practice in countries reaching malaria elimination should be aware of: lessons learnt from recent experience in Sri Lanka

Following progressive reduction in confirmed cases of malaria from 2002 to 2007 (41,411 cases in 2002, 10,510 cases in 2003, 3,720 cases in 2004, 1,640 cases in 2005, 591 cases in 2006, and 198 cases in 2007). Sri Lanka entered the pre-elimination stage of malaria in 2008. One case of indigenous malaria and four other cases of imported malaria are highlighted here, as the only patients who presented to the Professorial Medical Unit, Colombo North Teaching Hospital, Ragama, Sri Lanka over the past eight years, in contrast to treating several patients a week about a decade ago. Therefore, at the eve of elimination of malaria from Sri Lanka, it is likely that the infection is mostly encountered among travellers who return from endemic areas, or among the military who serve in un-cleared areas of Northern Sri Lanka. They may act as potential sources of introducing malaria as until malaria eradication is carried out. These cases highlight that change in the symptomatology, forgetfulness regarding malaria as a cause of acute febrile illness and deterioration of the competency of microscopists as a consequence of the low disease incidence, which are all likely to contribute to the delay in the diagnosis. The importance regarding awareness of new malaria treatment regimens, treatment under direct observation, prompt notification of suspected or diagnosed cases of malaria and avoiding blind use of anti-malarials are among the other responsibilities expected of all clinicians who manage patients in countries reaching malaria elimination

Basic Biomedical Sciences and the Future of Medical Education: Implications for Internal Medicine

The academic model of medical education in the United States is facing substantial challenges. Apprenticeship experiences with clinical faculty are increasingly important in most medical schools and residency programs. This trend threatens to separate clinical education from the scientific foundations of medical practice. Paradoxically, this devaluation of biomedical science is occurring as the ability to use new discoveries to rationalize clinical decision making is rapidly expanding. Understanding the scientific foundations of medical practice and the ability to apply them in the care of patients separates the physician from other health care professionals. The de-emphasis of biomedical science in medical education poses particular dangers for the future of internal medicine as the satisfaction derived from the application of science to the solving of a clinical problem has been a central attraction of the specialty. Internists should be engaged in the ongoing discussions of medical education reform and provide a strong voice in support of rigorous scientific training for the profession

Genic and Global Functions for Paf1C in Chromatin Modification and Gene Expression in Arabidopsis

In budding yeast, intragenic histone modification is linked with transcriptional elongation through the conserved regulator Paf1C. To investigate Paf1C-related function in higher eukaryotes, we analyzed the effects of loss of Paf1C on histone H3 density and patterns of H3 methylated at K4, K27, and K36 in Arabidopsis genes, and integrated this with existing gene expression data. Loss of Paf1C did not change global abundance of H3K4me3 or H3K36me2 within chromatin, but instead led to a 3′ shift in the distribution of H3K4me3 and a 5′ shift in the distribution of H3K36me2 within genes. We found that genes regulated by plant Paf1C showed strong enrichment for both H3K4me3 and H3K27me3 and also showed a high degree of tissue-specific expression. At the Paf1C- and PcG-regulated gene FLC, transcriptional silencing and loss of H3K4me3 and H3K36me2 were accompanied by expansion of H3K27me3 into the promoter and transcriptional start regions and further enrichment of H3K27me3 within the transcribed region. These results highlight both genic and global functions for plant Paf1C in histone modification and gene expression, and link transcriptional activity with cellular memory

Black tea extract prevents lipopolysaccharide-induced NF-κB signaling and attenuates dextran sulfate sodium-induced experimental colitis

<p>Abstract</p> <p>Background</p> <p>Black tea has been shown to elicit anti-oxidant, anti-carcinogenic, anti-inflammatory and anti-mutagenic properties. In this study, we investigated the impact of black tea extract (BTE) on lipopolysaccharide (LPS)-induced NF-κB signaling in bone marrow derived-macrophages (BMM) and determined the therapeutic efficacy of this extract on colon inflammation.</p> <p>Methods</p> <p>The effect of BTE on LPS-induced NF-κB signaling and pro-inflammatory gene expression was evaluated by RT-PCR, Western blotting, immunofluorescence and electrophoretic mobility shift assay (EMSA). The <it>in vivo </it>efficacy of BTE was assessed in mice with 3% dextran sulfate sodium (DSS)-induced colitis. The severity of colitis was measured by weight loss, colon length and histologic scores.</p> <p>Results</p> <p>LPS-induced IL-12p40, IL-23p19, IL-6 and IL-1β mRNA expressions were inhibited by BTE. LPS-induced IκBα phosphorylation/degradation and nuclear translocation of NF-κB/p65 were blocked by BTE. BTE treatment blocked LPS-induced DNA-binding activity of NF-κB. BTE-fed, DSS-exposed mice showed the less weight loss, longer colon length and lower histologic score compared to control diet-fed, DSS-exposed mice. DSS-induced IκBα phosphorylation/degradation and phosphorylation of NF-κB/p65 were blocked by BTE. An increase of cleaved caspase-3 and poly (ADP-ribose) polymerase (PARP) in DSS-exposed mice was blocked by BTE.</p> <p>Conclusions</p> <p>These results indicate that BTE attenuates colon inflammation through the blockage of NF-κB signaling and apoptosis in DSS-induced experimental colitis model.</p

Q344ter Mutation Causes Mislocalization of Rhodopsin Molecules That Are Catalytically Active: A Mouse Model of Q344ter-Induced Retinal Degeneration

Q344ter is a naturally occurring rhodopsin mutation in humans that causes autosomal dominant retinal degeneration through mechanisms that are not fully understood, but are thought to involve an early termination that removed the trafficking signal, QVAPA, leading to its mislocalization in the rod photoreceptor cell. To better understand the disease mechanism(s), transgenic mice that express Q344ter were generated and crossed with rhodopsin knockout mice. Dark-reared Q344terrho+/− mice exhibited retinal degeneration, demonstrating that rhodopsin mislocalization caused photoreceptor cell death. This degeneration is exacerbated by light-exposure and is correlated with the activation of transducin as well as other G-protein signaling pathways. We observed numerous sub-micrometer sized vesicles in the inter-photoreceptor space of Q344terrho+/− and Q344terrho−/− retinas, similar to that seen in another rhodopsin mutant, P347S. Whereas light microscopy failed to reveal outer segment structures in Q344terrho−/− rods, shortened and disorganized rod outer segment structures were visible using electron microscopy. Thus, some Q344ter molecules trafficked to the outer segment and formed disc structures, albeit inefficiently, in the absence of full length wildtype rhodopsin. These findings helped to establish the in vivo role of the QVAPA domain as well as the pathways leading to Q344ter-induced retinal degeneration

Toxoplasma gondii Infection in the Brain Inhibits Neuronal Degeneration and Learning and Memory Impairments in a Murine Model of Alzheimer's Disease

Immunosuppression is a characteristic feature of Toxoplasma gondii-infected murine hosts. The present study aimed to determine the effect of the immunosuppression induced by T. gondii infection on the pathogenesis and progression of Alzheimer's disease (AD) in Tg2576 AD mice. Mice were infected with a cyst-forming strain (ME49) of T. gondii, and levels of inflammatory mediators (IFN-γ and nitric oxide), anti-inflammatory cytokines (IL-10 and TGF-β), neuronal damage, and β-amyloid plaque deposition were examined in brain tissues and/or in BV-2 microglial cells. In addition, behavioral tests, including the water maze and Y-maze tests, were performed on T. gondii-infected and uninfected Tg2576 mice. Results revealed that whereas the level of IFN-γ was unchanged, the levels of anti-inflammatory cytokines were significantly higher in T. gondii-infected mice than in uninfected mice, and in BV-2 cells treated with T. gondii lysate antigen. Furthermore, nitrite production from primary cultured brain microglial cells and BV-2 cells was reduced by the addition of T. gondii lysate antigen (TLA), and β-amyloid plaque deposition in the cortex and hippocampus of Tg2576 mouse brains was remarkably lower in T. gondii-infected AD mice than in uninfected controls. In addition, water maze and Y-maze test results revealed retarded cognitive capacities in uninfected mice as compared with infected mice. These findings demonstrate the favorable effects of the immunosuppression induced by T. gondii infection on the pathogenesis and progression of AD in Tg2576 mice

The Werner Syndrome Helicase/Exonuclease Processes Mobile D-Loops through Branch Migration and Degradation

RecQ DNA helicases are critical for preserving genome integrity. Of the five RecQ family members identified in humans, only the Werner syndrome protein (WRN) possesses exonuclease activity. Loss of WRN causes the progeroid disorder Werner syndrome which is marked by cancer predisposition. Cellular evidence indicates that WRN disrupts potentially deleterious intermediates in homologous recombination (HR) that arise in genomic and telomeric regions during DNA replication and repair. Precisely how the WRN biochemical activities process these structures is unknown, especially since the DNA unwinding activity is poorly processive. We generated biologically relevant mobile D-loops which mimic the initial DNA strand invasion step in HR to investigate whether WRN biochemical activities can disrupt this joint molecule. We show that WRN helicase alone can promote branch migration through an 84 base pair duplex region to completely displace the invading strand from the D-loop. However, substrate processing is altered in the presence of the WRN exonuclease activity which degrades the invading strand both prior to and after release from the D-loop. Furthermore, telomeric D-loops are more refractory to disruption by WRN, which has implications for tighter regulation of D-loop processing at telomeres. Finally, we show that WRN can recognize and initiate branch migration from both the 5′ and 3′ ends of the invading strand in the D-loops. These findings led us to propose a novel model for WRN D-loop disruption. Our biochemical results offer an explanation for the cellular studies that indicate both WRN activities function in processing HR intermediates