Project description:Previously, we constructed a coculture model to analyze the effect of macrophages on intestinal epithelial cells, and found that TNF-a secreted from human macrophage-like THP-1 cells induced cell damage to intestinal epithelial Caco-2 cells (Exp.Cell.Res. 2006, 312(19):3909-19). In this study, we present activation of NF-kB in Caco-2 cells within 15 min after coculturing. To reveal how TNF-a secreted from THP-1 cells affects Caco-2 cells in an early stage of coculture, we exhaustively analyzed the changes of gene expression in Caco-2 cells cocultured with THP-1 cells over the time periods of 0, 1, 3, 6, 24, and 48 h by using a DNA microarray. Differentially expressed genes extracted with maSigPro demonstrated that IEX-1 was the lowest p-value gene, that is, the most significantly changed gene among the up-regulated genes. The genes expressed in a similar pattern to IEX-1 involved immunity, apoptosis, and protein kinase cascade. These findings suggest that the stimuli of TNF-a from THP-1 cells activates NF-kB, leading induction of various gene expression. This pattern of gene expression indicates that not only early defense response but also cell death occurs at the same time, causing inflammatory condition. Caco-2 cells were cultured for 14 days on a semi-permeable support, and THP-1 cells were differentiated with phorbol myristate acetate (PMA) for 4 days in 12-well plates. Then, the semi-permeable support membrane in which Caco-2 cells had been cultured was placed on the 12-well plates on which THP-1 has been cultured.
Project description:Previously, we constructed a coculture model to analyze the effect of macrophages on intestinal epithelial cells, and found that TNF-a secreted from human macrophage-like THP-1 cells induced cell damage to intestinal epithelial Caco-2 cells (Exp.Cell.Res. 2006, 312(19):3909-19). In this study, we present activation of NF-kB in Caco-2 cells within 15 min after coculturing. To reveal how TNF-a secreted from THP-1 cells affects Caco-2 cells in an early stage of coculture, we exhaustively analyzed the changes of gene expression in Caco-2 cells cocultured with THP-1 cells over the time periods of 0, 1, 3, 6, 24, and 48 h by using a DNA microarray. Differentially expressed genes extracted with maSigPro demonstrated that IEX-1 was the lowest p-value gene, that is, the most significantly changed gene among the up-regulated genes. The genes expressed in a similar pattern to IEX-1 involved immunity, apoptosis, and protein kinase cascade. These findings suggest that the stimuli of TNF-a from THP-1 cells activates NF-kB, leading induction of various gene expression. This pattern of gene expression indicates that not only early defense response but also cell death occurs at the same time, causing inflammatory condition.
Project description:Kynureninase is a member of a large family of catalytically diverse but structurally homologous pyridoxal 5'-phosphate (PLP) dependent enzymes known as the aspartate aminotransferase superfamily or alpha-family. The Homo sapiens and other eukaryotic constitutive kynureninases preferentially catalyze the hydrolytic cleavage of 3-hydroxy-l-kynurenine to produce 3-hydroxyanthranilate and l-alanine, while l-kynurenine is the substrate of many prokaryotic inducible kynureninases. The human enzyme was cloned with an N-terminal hexahistidine tag, expressed, and purified from a bacterial expression system using Ni metal ion affinity chromatography. Kinetic characterization of the recombinant enzyme reveals classic Michaelis-Menten behavior, with a Km of 28.3 +/- 1.9 microM and a specific activity of 1.75 micromol min-1 mg-1 for 3-hydroxy-dl-kynurenine. Crystals of recombinant kynureninase that diffracted to 2.0 A were obtained, and the atomic structure of the PLP-bound holoenzyme was determined by molecular replacement using the Pseudomonas fluorescens kynureninase structure (PDB entry 1qz9) as the phasing model. A structural superposition with the P. fluorescens kynureninase revealed that these two structures resemble the "open" and "closed" conformations of aspartate aminotransferase. The comparison illustrates the dynamic nature of these proteins' small domains and reveals a role for Arg-434 similar to its role in other AAT alpha-family members. Docking of 3-hydroxy-l-kynurenine into the human kynureninase active site suggests that Asn-333 and His-102 are involved in substrate binding and molecular discrimination between inducible and constitutive kynureninase substrates.