Isolation of cDNA Encoding 7H6-Reactive Polypeptide Defines a New Class of Protein with alpha-Helical Coiled-Coil Structure and DA-Box Similar to Yeast Chromosomal Segregation Proteins

7H6 monoclonal antibody was recently developed in our laboratory by im-munizing mice with a bile canaliculus-rich fraction of the rat liver. The anti-body reacted with a novel 155 Kd polypeptide designated 7H6 antigen that specifically localizes at tight junctions of various epithelia. Correlations of the paracellular barrier function of the tight junction with expression of the 7H6 antigen at the cell border have suggested important roles of this polypeptide for the maintenance of tight junctional functions. As the first step for the analysis of the antigen at the molecular level, we isolated a series of cDNA clones encod-ing 7H6-reactive polypeptides. Five clones were isolated by immunoscreening. Among them a clone designated RL5.3 which carries the largest 5.3Kb insert was characterized in this study. Both plaque screening and immunoblotting of the fusion protein produced by the RL5.3 clone with lysogen confirmed that the pro-tein specifically reacts with the 7H6 monoclonal antibody. Using DNA fragmentsof the RL5.3 clone, 21 clones were further identified. Studies with restriction enzymes and probe hybridization revealed that all the cDNA clones were derived from a single class of transcripts. A partial sequence identified one open reading frame with an α-helical coiled-coil structure and highly conserved aspartate (D)- alanine (A) residues with a helix-loop-helix structure corresponding to DA- box. Since this domain has been specifically found in yeast chromosomal segregation proteins (SMC1, CUT3 and CUT14), the polypeptide encoded by the RL5.3 clone provides the first rodent counterpart of these protein family. Yeast is known to be lethal when SMC and CUT proteins are deleted, suggesting essential roles of these proteins for cell cycle progression as a regulator for chromosomal segregation. Identification of a mammalian counterpart of this pro-tein family may give us some clues for a better understanding of fundamental regulatory mechanisms in the function of tigh junctions

MRGD, a MAS-related G-protein Coupled Receptor, Promotes Tumorigenisis and Is Highly Expressed in Lung Cancer

To elucidate the function of MAS-related GPCR, member D (MRGD) in cancers, we investigated the in vitro and in vivo oncogenic function of MRGD using murine fibroblast cell line NIH3T3 in which MRGD is stably expressed. The expression pattern of MRGD in clinical samples was also analyzed. We found that overexpression of MRGD in NIH3T3 induced focus formation and multi-cellular spheroid formation, and promoted tumors in nude mice. In other words, overexpression of MRGD in NIH3T3 induced the loss of contact inhibition, anchorage-independent growth and in vivo tumorigenesis. Furthermore, it was found that the ligand of MRGD, beta-alanine, enhanced spheroid formation in MRGD-expressing NIH3T3 cells. From investigation of clinical cancer tissues, we found high expression of MRGD in several lung cancers by immunohistochemistry as well as real time PCR. Based on these results, MRGD could be involved in tumorigenesis and could also be a novel anticancer drug target

A Novel Method for Inducing Amastigote-To-Trypomastigote Transformation In Vitro in Trypanosoma cruzi Reveals the Importance of Inositol 1,4,5-Trisphosphate Receptor

Background Trypanosoma cruzi is a parasitic protist that causes Chagas disease, which is prevalent in Latin America. Because of the unavailability of an effective drug or vaccine, and because about 8 million people are infected with the parasite worldwide, the development of novel drugs demands urgent attention. T. cruzi infects a wide variety of mammalian nucleated cells, with a preference for myocardial cells. Non-dividing trypomastigotes in the bloodstream infect host cells where they are transformed into replication-capable amastigotes. The amastigotes revert to trypomastigotes (trypomastigogenesis) before being shed out of the host cells. Although trypomastigote transformation is an essential process for the parasite, the molecular mechanisms underlying this process have not yet been clarified, mainly because of the lack of an assay system to induce trypomastigogenesis in vitro. Methodology/Principal Findings Cultivation of amastigotes in a transformation medium composed of 80% RPMI-1640 and 20% Grace\u27s Insect Medium mediated their transformation into trypomastigotes. Grace\u27s Insect Medium alone also induced trypomastigogenesis. Furthermore, trypomastigogenesis was induced more efficiently in the presence of fetal bovine serum. Trypomastigotes derived from in vitro trypomastigogenesis were able to infect mammalian host cells as efficiently as tissue-culture-derived trypomastigotes (TCT) and expressed a marker protein for TCT. Using this assay system, we demonstrated that T. cruzi inositol 1,4,5-trisphosphate receptor (TcIP3R) - an intracellular Ca2+ channel and a key molecule involved in Ca2+ signaling in the parasite - is important for the transformation process. Conclusion/Significance Our findings provide a new tool to identify the molecular mechanisms of the amastigote-totrypomastigote transformation, leading to a new strategy for drug development against Chagas disease

Physicochemical properties and plastic crystal structures of phosphonium fluorohydrogenate salts.

Fluorohydrogenate salts of quaternary phosphonium cations with alkyl and methoxy groups (tetraethylphosphonium (P(2222)(+)), triethyl-n-pentylphosphonium (P(2225)(+)), triethyl-n-octylphosphonium (P(2228)(+)), and triethylmethoxymethylphosphonium (P(222(101))(+))) have been synthesized by the metatheses of anhydrous hydrogen fluoride and the corresponding phosphonium bromide or chloride precursors. The three salts with asymmetric cations, P(222m)(FH)(2.1)F (m = 5, 8, and 101), are room temperature ionic liquids (ILs) and are characterized by differential scanning calorimetry, density, viscosity, and conductivity measurements. Linear sweep voltammetry using a glassy carbon working electrode shows these phosphonium fluorohydrogenate ILs have wide electrochemical windows (>4.9 V) with the lowest viscosity and highest conductivity in the known phosphonium-based ILs. Thermogravimetry shows their thermal stabilities are also improved compared to previously reported alkylammonium cation-based fluorohydrogenate salts. Differential scanning calorimetry and X-ray diffraction revealed that tetraethylphosphonium fluorohydrogenate salt, P(2222)(FH)(2)F, exhibits two plastic crystal phases. The high temperature phase has a hexagonal lattice, which is the first example of a plastic crystal phase with an inverse nickel arsenide-type structure, and the low-temperature phase has an orthorhombic lattice. The high-temperature plastic crystal phase exhibits a conductivity of 5 mS cm(-1) at 50 °C, which is the highest value for the neat plastic crystals

Characterization of Atypical Enteropathogenic Escherichia coli Strains Harboring the astA Gene That Were Associated with a Waterborne Outbreak of Diarrhea in Japan

The virulence traits of the Escherichia coli strain associated with a waterborne diarrhea outbreak were examined. Forty-one of 75 students (ages 12 to 15) in Akita Prefecture, Japan, showed clinical symptoms. Seven E. coli Ouk:K-:H45 isolates were isolated from the patients as the causative agent of this outbreak. One isolate (EC-3605) showed the presence of E. coli attaching-and-effacing (eaeA) and enteroaggregative E. coli heat-stable enterotoxin-1 (astA) genes and the absence of Shiga toxin (stx1 and stx2) genes. A polymorphic enteropathogenic E. coli (EPEC) adherence factor plasmid was detected in EC-3605 with a major structural gene deletion and a regulatory gene frameshift mutation, revealing that EC-3605 represents an atypical EPEC strain harboring the astA gene. The role that atypical EPEC strains harboring the astA gene play in human disease is unclear. Our results, along with those of others, present a possibility that these strains comprise a distinct category of diarrheagenic E. coli and that astA affects the age distribution of atypical-EPEC infection