Cloning and expression of a complementary DNA encoding a bovine adrenal angiotensin II type-1 receptor

Angiotensin II elicits different responses which affect cardiovascular, neuronal and electrolyte transport regulation. To understand the mechanisms responsible for its various actions, the receptor for angiotensin II has long been sought, but numerous attempts to purify the receptor have been unsuccessful owing to its instability and low concentration. We report here the expression cloning of a complementary DNA encoding a bovine angiotensin II receptor to overcome these difficulties. The receptor cDNA encodes a protein of 359 amino-acid residues with a transmembrane topology similar to that of other G protein-coupled receptors. COS-7 cells transfected with the cDNA expressed specific and high-affinity binding sites for angiotensin II, angiotensin II antagonist and a non-peptide specific antagonist for type-1 receptor. Dithiothreitol inhibited ligand binding. The concentration of intracellular Ca2+ and of inositol-1,4,5-trisphosphate increased in the transfected COS-7 cells in response to angiotensin II or angiotensin III, indicating that this receptor is the type-1 receptor for angiotensin II. Northern blot analysis revealed that the messenger RNA for this receptor is expressed in bovine adrenal medulla, cortex and kidney.     

Hierarchical hypergames and Bayesian games: A generalization of the theoretical comparison of hypergames and Bayesian games considering hierarchy of perceptions

This paper discusses the relationship of two independently developed models of games with incomplete information, hierarchical hypergames and Bayesian games. It can be considered as a generalization of the previous study on the theoretical comparison of simple hypergames and Bayesian games (Sasaki and Kijima, 2012) by taking into account hierarchy of perceptions, i.e., an agent’s perception about the other agents’ perceptions, and so on. The authors first introduce the general way of transformation of any hierarchical hypergames into corresponding Bayesian games, which was called as the Bayesian representation of hierarchical hypergames. The authors then show that some equilibrium concepts for hierarchical hypergames can be associated with those for Bayesian games and discuss implications of the results.     

Phosphoglycerate dehydrogenase diverts glycolytic flux and contributes to oncogenesis

Most tumors exhibit increased glucose metabolism to lactate, however, the extent to which glucose-derived metabolic fluxes are used for alternative processes is poorly understood. Using a metabolomics approach with isotope labeling, we found that in some cancer cells a relatively large amount of glycolytic carbon is diverted into serine and glycine metabolism through phosphoglycerate dehydrogenase (PHGDH). An analysis of human cancers showed that PHGDH is recurrently amplified in a genomic region of focal copy number gain most commonly found in melanoma. Decreasing PHGDH expression impaired proliferation in amplified cell lines. Increased expression was also associated with breast cancer subtypes, and ectopic expression of PHGDH in mammary epithelial cells disrupted acinar morphogenesis and induced other phenotypic alterations that may predispose cells to transformation. Our findings show that the diversion of glycolytic flux into a specific alternate pathway can be selected during tumor development and may contribute to the pathogenesis of human cancer.     

Insect signalling: components of giant hornet alarm pheromone

Up to 74 people die each year in Japan after being stung by Hymenopteran insects, with hornets (Vespa spp.) being among the worst offenders. Here we identify a volatile, multi-component alarm pheromone in the venom of the world's largest hornet, V. mandarinia, and use field bioassays to show that 2-pentanol is its principal active component, and that 3-methyl-1-butanol and 1-methylbutyl 3-methylbutanoate act synergistically with it. The compound 1-methylbutyl 3-methylbutanoate, which may also be a foraging-site-marking pheromone, elicits a strong defensive reaction in the sympatric prey hornet V. simillima xanthoptera. As these chemicals are sometimes used in food flavourings and as fragrances in cosmetics, it is possible that they might provoke a seemingly unwarranted hornet attack on humans.     

Loss of constitutional heterozygosity in colon carcinoma from patients with familial polyposis coli

Recent studies have suggested a critical role of specific gene loss in several embryonic tumours and certain adult cancers. In retinoblastoma, hemizygosity or homozygosity of a recessive mutant allele results in the loss of normal gene product, and this seems to cause the manifestation of the disorder. Familial polyposis coli (FPC) is a human autosomal dominant trait characterized by numerous adenomatous polyps of the colon and rectum, and a high incidence of colon carcinoma. Karyotype analyses have failed to detect specific deletion or translocation. We report the use of polymorphic DNA markers to look for the somatic loss of heterozygosity at specific loci. Investigation of 38 tumours from 25 FPC patients, and 20 sporadic colon carcinomas from 19 patients, revealed frequent occurrence of allele loss on chromosome 22, with some additional losses on chromosomes 5, 6, 12q and 15. The FPC gene-linked DNA probe C11p11 also detected frequent allele loss in both familial and sporadic colon carcinomas but not in benign adenomas. These results suggest the possible involvement of more than one chromosomal locus in the development of familial and sporadic colon carcinomas.     

Wip1 protects hydrogen peroxide-induced colonic epithelial barrier dysfunction

Tight junctions (TJs) create a paracellular permeability barrier. Although reactive oxygen species have been implicated as mediators of inflammation in inflammatory bowel diseases, their influence on the function of colonic epithelial TJs remains unknown. Oxidative stress-mediated colonic epithelial permeability was significantly attenuated by a p38 mitogen-activated protein (MAP) kinase inhibitor, SB203580. Although the amount of TJ proteins was not altered, hydrogen peroxide (H₂O₂) changed the localization of claudin-4 protein from an NP-40 insoluble fraction to a soluble fraction and from an apical TJ to lateral membrane. The p38 MAP kinase inactivator Wip1 significantly attenuated phosphorylation of p38 MAP kinase, and oxidative stress mediated permeability. H₂O₂-induced changes in claudin-4 localization were abolished by SB203580 pretreatment as well as Wip1-expressing adenovirus infection. This is the first study to demonstrate that exogenous Wip1 functions to protect oxidative stress-mediated colonic mucosal permeability and that H₂O₂-induced claudin-4 dislocalization is abolished by Wip1. Received 14 June 2007; received after revision 8 October 2007; accepted 8 October 2007     

JNK1-dependent antimitotic activity of thiazolidin compounds in human non-small-cell lung and colon cancer cells

We recently identified two thiazolidin compounds, 5-[(4-methylphenyl)methylene]-2-(phenylamino)-4(5H)-thiazolone (MMPT) and 5-(2,4-dihydroxybenzylidene)-2-(phenylimino)-1,3-thiazolidin (DBPT), that inhibit the growth of human non-small-cell lung and colon cancer cells independent of P-glycoprotein and p53 status. Here we further investigated the mechanism by which these thiazolidin compounds mediate their anticancer effects. Treatment of cancer cells with MMPT and DBPT led to a time-dependent accumulation of cells arrested in the G2/M phase with modulation of the expression of proteins such as cyclin B1, cdc25C, and phosphorylated histone H3. Moreover, treatment with MMPT and DBPT increased M-phase arrest with abnormal spindle formation. DBPT-mediated G2/M phase arrest and phosphorylation of cdc25C and histone H3 were abrogated when JNK activation was blocked either with SP600125, a specific JNK inhibitor, or a dominant-negative JNK1 gene. Moreover, DBPT-mediated microtubule disruption was also blocked by SP600125 treatment. Our results demonstrate that thiazolidin compounds can effectively induce G2/M arrest in cancer cells and that this G2/M arrest requires JNK activation.