Importance of the alternative NF-κB activation pathway in inflammation-associated gastrointestinal carcinogenesis

Chronic inflammation is a common factor in the development of many gastrointestinal malignancies. Examples include inflammatory bowel disease predisposing to colorectal cancer, Barrett's esophagus as a precursor of esophageal adenocarcinoma, and Helicobacter pylori-induced gastric cancer. The classical activation pathway of NF-κB signaling has been identified as regulating several sporadic and inflammation-associated gastrointestinal tract malignancies. Emerging evidence suggests that the alternative NF-κB signaling pathway also exerts a distinct influence on these processes. This review brings together current knowledge of the role of the alternative NF-κB signaling pathway in the gastrointestinal tract, with a particular emphasis on inflammation-associated cancer development. members of the nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB) family were initially described as transcription factors in B lymphocytes in 1986 (68). Since then, they have been shown to be widely expressed and are conserved across both vertebrates and invertebrates (5, 27). The conventional model of NF-κB signaling proposes two main arms of the pathway. These share similar features but are triggered independently and activate different target genes (76). The classical (canonical) NF-κB activation pathway is triggered by Th1 cytokines and is typified by the action of reticuloendotheliosis viral oncogene homolog A (RelA) (p65)-NF-κB1(p50) heterodimers, whereas the alternative (noncanonical) activation pathway signals through the adaptor protein NF-κB-inducing kinase (NIK). Activation of this mechanism leads to nuclear translocation of transcriptionally active v-rel avian reticuloendotheliosis viral oncogene homolog B (RelB)-NF-κB2(p52) heterodimers. Signaling through either pathway can influence multiple different cellular functions and can exert effects that may appear contradictory. For example, both pro- and anti-apoptotic effects, as well as proliferation (18) and senescence (70) signals, have been attributed to the classical activation pathway of NF-κB signaling. Because of the wide variation in outcomes following pathway activation, it is difficult to extrapolate the effects of NF-κB signaling from one context to another. Classical pathway NF-κB signaling has been identified as a key regulator of inflammation-associated carcinogenesis in several tissues since the early 2000s when Greten et al. demonstrated increased sensitivity to colitis-associated carcinogenesis in mice lacking IKK-β in intestinal epithelial cells (31), and, almost simultaneously Pikarsky et al. identified a similar increase in tumor burden in Mdr2 mice lacking IKK-β in hepatocytes (60). More recent evidence has established that alternative activation pathway NF-κB signaling is also important during the development of several gastrointestinal pathologies in mouse and humans. This article seeks to review this evidence and to establish questions for future research

Transcriptome analysis of a parasitic clade V nematode:comparative analysis of potential molecular anthelmintic targets in Cylicostephanus goldi

AbstractClade V nematodes comprise several parasitic species that include the cyathostomins, primary helminth pathogens of horses. Next generation transcriptome datasets are available for eight parasitic clade V nematodes, although no equine parasites are included in this group. Here, we report next generation transcriptome sequencing analysis for the common cyathostomin species, Cylicostephanus goldi. A cDNA library was generated from RNA extracted from 17 C. goldi male and female adult parasites. Following sequencing using a 454 GS FLX pyrosequencer, a total of 475,215 sequencing reads were generated, which were assembled into 26,910 contigs. Using Gene Ontology and Kyoto Encyclopedia of Genes and Genomes databases, 27% of the transcriptome was annotated. Further in-depth analysis was carried out by comparing the C. goldi dataset with the next generation transcriptomes and genomes of other clade V nematodes, with the Oesophagostomum dentatum transcriptome and the Haemonchus contortus genome showing the highest levels of sequence identity with the cyathostomin dataset (45%). The C. goldi transcriptome was mined for genes associated with anthelmintic mode of action and/or resistance. Sequences encoding proteins previously associated with the three major anthelmintic classes used in horses were identified, with the exception of the P-glycoprotein group. Targeted resequencing of the glutamate gated chloride channel α4 subunit (glc-3), one of the primary targets of the macrocyclic lactone anthelmintics, was performed for several cyathostomin species. We believe this study reports the first transcriptome dataset for an equine helminth parasite, providing the opportunity for in-depth analysis of these important parasites at the molecular level. Sequences encoding enzymes involved in key processes and genes associated with levamisole/pyrantel and macrocyclic lactone resistance, in particular the glutamate gated chloride channels, were identified. This novel data will inform cyathostomin biology and anthelmintic resistance studies in future

Exploring the diversity of arcobacter butzleri from cattle in the UK using MLST and whole genome sequencing

<div><p><em>Arcobacter butzleri</em> is considered to be an emerging human foodborne pathogen. The completion of an <em>A. butzleri</em> genome sequence along with microarray analysis of 13 isolates in 2007 revealed a surprising amount of diversity amongst <em>A. butzleri</em> isolates from humans, animals and food. In order to further investigate <em>Arcobacter</em> diversity, 792 faecal samples were collected from cattle on beef and dairy farms in the North West of England. <em>Arcobacter</em> was isolated from 42.5% of the samples and the diversity of the isolates was investigated using multilocus sequence typing. An <em>A. butzleri</em> whole genome sequence, obtained by 454 shotgun sequencing of an isolate from a clinically-healthy dairy cow, showed a number of differences when compared to the genome of a human-derived <em>A. butzleri</em> isolate. PCR-based prevalence assays for variable genes suggested some tentative evidence for source-related distributions. We also found evidence for phenotypic differences relating to growth capabilities between our representative human and cattle isolates. Our genotypic and phenotypic observations suggest that some level of niche adaptation may have occurred in <em>A. butzleri</em>.</p> </div

Example of metabolic variation between sequenced isolates.

<p>Omnilog output chart showing the growth curves of 7h1h (blue) and RM4018 (red) using L-asparagine and L-glutamic acid as carbon sources over a time period of 72 hours. Each isolate was tested in duplicate, hence 7h1ha, 7h1hb, RM4018a and RM4018b. The red and blue lines along the bottom of the charts include negative controls for each isolate.</p

The main phenotypic differences as determined by Omnilog analysis of 7h1h and RM4018.+represents growth and – represents no growth of the isolate on the omnilog plate.

<p>The main phenotypic differences as determined by Omnilog analysis of 7h1h and RM4018.+represents growth and – represents no growth of the isolate on the omnilog plate.</p

Oligonucleotide sequences and expected product sizes for primers designed to detect the presence of variable genes between <i>Arcobacter</i> isolates.

<p>Oligonucleotide sequences and expected product sizes for primers designed to detect the presence of variable genes between <i>Arcobacter</i> isolates.</p

Subsystems identified by RAST in isolates 7h1h and RM4018.

<p>Subsystems identified by RAST in isolates 7h1h and RM4018.</p

Details of the 50 <i>Arcobacter butzleri</i> isolates used to screen for the distribution of variable regions by PCR and the distribution of the genes.

<p>Details of the 50 <i>Arcobacter butzleri</i> isolates used to screen for the distribution of variable regions by PCR and the distribution of the genes.</p