by Quantitative Pomalidomide supplier RT-PCR Quantitation of mRNA levels was performed by the CHDD Genomics Core Laboratory using fluorogenic 59 nuclease-based assays and has been previously described.. Supporting Information Acknowledgments We gratefully acknowledge the technical assistance of Jennifer Summers in preparing the figures. Intestinal epithelial cells participate in immune regulation and mucosal integrity. Tight junctions constitute continuous circumferential seals around cells and serve as a protective barrier, preventing solutes and water from passing freely through the paracellular pathway. Tight junctions can be altered by various pathogens, as well as by their toxins. These effects may result from direct modification of TJ proteins such as occludin, claudin, and ZO-1, or by alteration of the perijunctional actomyosin ring. Salmonella enterica serovar Typhimurium is a major cause of human gastroenteritis. Infection of polarized epithelial cell monolayers by S. Typhimurium disrupts TJ structure and function. TJ disruption is dependent on the type III secretory system of Salmonella. TTSS is a needle-like protein transport device used by Gram-negative pathogenic bacteria. It allows bacteria to inject virulence effectors into eukaryotic host cells. TTSS is encoded by the Salmonella pathogenicity island 1 . A recent study indicated that SopB, SopE, SopE2, and SpiA are the TTSS secreted SPI-1 effectors responsible for the disruption of TJ structure and function. The specific bacterial 19770292 effectors responsible for the regulation of TJs, however, remains to be identified. The majority of published studies regarding Salmonella and TJ have utilized in vitro cultured epithelial models. The physiological consequences of Salmonella-effector-induced alteration of TJ function need to be addressed in vivo using animal models. AvrA is a newly described bacterial effector transported into the host cell by the TTSS of Salmonella. It also belongs to the SPI1. The SPI-1 effectors are responsible for early inflammation in the mouse model of S. Typhimurium-induced enterocolitis. AvrA protein from Salmonella Typhimurium inhibits activation of the proinflammatory NF-kB transcription factor 15034210 in cultured human epithelial cells. Based on the sequence alignment, AvrA belongs to the cysteine protease family. Representative AvrA members include the adenovirus-like proteases, YopJ, and AvrBsT. The catalytic triad for the cysteine protease is present in all AvrA family AvrA Tight Junction members. Further studies demonstrated that expression of a mutant AvrA protein with a single amino acid residue transition in a putative catalytic cysteine of this enzyme did not inhibit TNFa-stimulated induction of the reporter. We recently demonstrate that AvrA has deubiquitinase activity which removes ubiquitins from ub-IkBa, thus inhibiting NF-kB activity. AvrA C186A mutant protein had reduced deubiquitinase activity as evidenced by cleaving less ubiquitin moieties from IkBa. This data further supports the hypothesis that AvrA protein has protease activity which attenuates the proinflammatory NF-kB pathway. The AvrA gene is present in 80% of Salmonella enterica serovars. The protein expression of AvrA 
differs strikingly between bacterial strains in systemic disease and in enteritis which is localized to the intestine. AvrA protein was not expressed in strains related to systemic disease, but was conditionally expressed in the enteritis-related strains. In addition, S. enterica strains from
