No abstract

Alterations in splicing patterns of genes contribute to the regulation of gene function by generating endogenous inhibitor or activator molecules. Nucleotide-binding and oligomerization domain (NOD) 2 is an intracellular receptor for bacterial cell wall components and plays an important role in initiating immune responses against cytoinvasive pathogens. NOD2 overexpression sensitizes intestinal epithelial cells toward bacterial cell wall components, activates the proinflammatory transcription factor NF-B, and induces the subsequent release of the chemotactic cytokine IL-8. Here, we have assessed the regulation and function of a transcript isoform of NOD2, NOD2-S, generated by the skipping of the third exon, which encodes for a protein that is truncated within the second caspase recruitment (CARD) domain. NOD2-S is preferentially expressed in the human colon and is up-regulated by the antiinflammatory cytokine IL-10. Overexpression of NOD2-S downregulates NOD2-induced NF-B activation and IL-8 release. Moreover, NOD2-S also interferes with the maturation and secretion of pro-IL-1␤ downstream of NOD2 and its adaptor molecule receptorinteracting protein kinase 2. We provide a molecular basis for these effects, as we show that NOD2-S interacts with both, NOD2 and receptor-interacting protein kinase 2 and inhibits the ''nodosome'' assembly by interfering with the oligomerization of NOD2. These data unveil another level of complexicity in the regulation of intracellular innate immunity and may have important implications for the molecular understanding of NOD͞NALP protein-driven disease pathophysiology.alternative splicing ͉ cytokine ͉ inflammation ͉ innate immunity ͉ Crohn's disease

Abberrant DNA methylation is one of the hallmarks of cancerogenesis. Our study aims to delineate differential DNA methylation in cirrhosis and hepatic cancerogenesis. Patterns of methylation of 27,578 individual CpG loci in 12 hepatocellular carcinomas (HCCs), 15 cirrhotic controls and 12 normal liver samples were investigated using an array-based technology. A supervised principal component analysis (PCA) revealed 167 hypomethylated loci and 100 hypermethylated loci in cirrhosis and HCC as compared to normal controls. Thus, these loci show a ''cirrhotic'' methylation pattern that is maintained in HCC. In pairwise supervised PCAs between normal liver, cirrhosis and HCC, eight loci were significantly changed in all analyses differentiating the three groups (p < 0.0001). Of these, five loci showed highest methylation levels in HCC and lowest in control tissue (LOC55908, CELSR1, CRMP1, GNRH2, ALOX12 and ANGPTL7), whereas two loci showed the opposite direction of change (SPRR3 and TNFSF15). Genes hypermethylated between normal liver to cirrhosis, which maintain this methylation pattern during the development of HCC, are depleted for CpG islands, high CpG content promoters and polycomb repressive complex 2 (PRC2) targets in embryonic stem cells. In contrast, genes selectively hypermethylated in HCC as compared to nonmalignant samples showed an enrichment of CpG islands, high CpG content promoters and PRC2 target genes (p < 0.0001). Cirrhosis and HCC show distinct patterns of differential methylation with regards to promoter structure, PRC2 targets and CpG islands.Hepatocellular carcinoma (HCC) is the most common primary liver malignancy and globally the third most common cause of cancer mortality. 1,2 Approximately one million new cases are diagnosed globally each year. The highest incidences are observed in sub-Saharan Africa and Eastern Asia, where hepatitis B virus and hepatitis C virus infections are endemic. HCC incidence is rising also due to an increase in incidence of alcoholic cirrhosis and nonalcoholic steatohepatitis. 3,4 As for many other tumors, the development of HCC is a multistep process characterized by the accumulation of genetic and epigenetic alterations leading to the activation of oncogenes and inactivation or loss of tumor suppressor genes. Genomic alterations as part of the somatic evolution of the cancer genome are common in human cancer in general and also in

The sterolin locus ( ABCG5/ABCG8 ) confers susceptibility for cholesterol gallstone disease in humans. Both the responsible variant and the molecular mechanism causing an increased incidence of gallstones in these patients have as yet not been identified. Genetic mapping utilized patient samples from Germany (2,808 cases, 2,089 controls), Chile (680 cases, 442 controls), Denmark (366 cases, 766 controls), India (247 cases, 224 controls), and China (280 cases, 244 controls). Analysis of allelic imbalance in complementary DNA (cDNA) samples from human liver (n = 22) was performed using pyrosequencing. Transiently transfected HEK293 cells were used for [3H]-cholesterol export assays, analysis of protein expression, and localization of allelic constructs. Through fine mapping in German and Chilean samples, an ˜250 kB disease-associated interval could be defined for this locus. Lack of allelic imbalance or allelic splicing of the ABCG5 and ABCG8 transcripts in human liver limited the search to coding single nucleotide polymorphisms. Subsequent mutation detection and genotyping yielded two disease-associated variants: ABCG5-R50C ( P = 4.94 × 10−9) and ABCG8-D19H ( P = 1.74 × 10−10) in high pairwise linkage disequilibrium ( r 2 = 0.95). [3H]-cholesterol export assays of allelic constructs harboring these genetic candidate variants demonstrated increased transport activity (3.2-fold, P = 0.003) only for the ABCG8-19H variant, which was also superior in nested logistic regression models in German ( P = 0.018), Chilean ( P = 0.030), and Chinese ( P = 0.040) patient samples. Conclusion : This variant thus provides a molecular basis for biliary cholesterol hypersecretion as the mechanism for cholesterol gallstone formation, thereby drawing a link between “postgenomic” and “pregenomic” pathophysiological knowledge about this common complex disorder.