Fong-Fong Chu

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The aryl hydrocarbon (Ah) receptor binds various environmental pollutants, such as polycyclic aromatic hydrocarbons, heterocyclic amines, and polychlorinated aromatic compounds (dioxins, dibenzofurans, and biphenyls), and mediates the carcinogenic effects of these agents. The complementary DNA and part of the gene for an 87-kilodalton human protein that is(More)
Glutathione peroxidase (GPX)-1 and gastrointestinal (GI) epithelium-specific GPX (GPX-GI), encoded by Gpx1 and Gpx2, provide most GPX activity in GI epithelium. Although homozygous mice deficient in either the Gpx1 or Gpx2 gene appeared to be normal under standard housing conditions, homozygous mice deficient in both genes, double-knockout (KO) mice, had(More)
We have characterized a new selenium-dependent glutathione peroxidase, GSHPx-GI, by expressing a GSHPx-GI cDNA isolated from human hepatoma HepG2 cells in human mammary carcinoma MCF-7 cells, which have virtually undetectable expression of either the classical cellular enzyme, GSHPx-1, or GSHPx-GI at the protein level. One of the G418-resistant clones,(More)
We analyzed the expression of plasma glutathione peroxidase (GSHPx-P) messenger RNA (mRNA) in mouse, rat, and human tissues, using a human GSHPx-P cDNA clone as the probe. Unlike the classical cellular glutathione peroxidase (GSHPx-1), GSHPx-P expression appears to be tissue-specific. In the mouse and rat, kidney expresses an mRNA at a high level detected(More)
Increase in reactive oxygen species plays an integral part in the inflammatory response, and chronic inflammation increases cancer risk. Selenium-dependent glutathione peroxidase (GPX) is well recognized for its antioxidant, and thus anti-inflammatory, activity. However, due to the multiple antioxidant families present in the gastrointestinal tract, it has(More)
Mitochondria have GPX and PHGPX activity. It has been an unsettled issue whether mitochondrial GPX is encoded by Gpx1. Unlike the Gpx4 gene which encodes PHGPX with alternative transcription and translation start sites determining the subcellular localization of PHGPX, the Gpx1 gene appears to have a single translation start site. Additionally,(More)
Chronic inflammation and selenium deficiency are considered as risk factors for colon cancer. The protective effect of selenium might be mediated by specific selenoproteins, such as glutathione peroxidases (GPx). GPx-1 and -2 double knockout, but not single knockout mice, spontaneously develop ileocolitis and intestinal cancer. Since GPx2 is induced by the(More)
Virus-transformed fibroblasts show an increased production of proteases as well as loss of extracellular adhesive proteins. To determine whether these transformation-associated events are related, we investigated the capacity of Rous sarcoma virus-transformed cells (embryonic chick fibroblasts and mouse BALB/c 3T3) to degrade fibronectin by using a novel(More)
Epigenetic changes are strongly associated with cancer development. DNA hypermethylation is associated with gene silencing and is often observed in CpG islands. Recently, it was suggested that aberrant CpG island methylation in tumors is directed by Polycomb (PcG) proteins. However, specific mechanisms responsible for methylation of PcG target genes in(More)
Localization of glutathione peroxidase 2 (GPx2), the gastrointestinal form of GPx's, in the intestinal crypt epithelium points to a specific but so-far unknown function of this particular GPx. Therefore, the consequences of a GPx2 knockout were tested in mice fed a selenium-restricted, Se-adequate, or Se-supplemented diet. An unexpected increase in total(More)