黄嘌呤脱氢酶
黄嘌呤氧化酶
黄嘌呤
生物
细胞因子
炎症
环己酰亚胺
生物化学
内科学
免疫学
酶
医学
蛋白质生物合成
作者
Kathleen Pfeffer,Thomas P. Huecksteadt,John R. Hoidal
出处
期刊:Journal of Immunology
[The American Association of Immunologists]
日期:1994-08-15
卷期号:153 (4): 1789-1797
被引量:142
标识
DOI:10.4049/jimmunol.153.4.1789
摘要
Reactive oxygen species have been implicated in the tissue injury and loss of epithelial barrier function associated with a number of clinical disorders in which disregulated inflammation seems to be a dominant event, such as endotoxemia and viral syndromes. In these disorders, xanthine oxidase (XO) contained within the epithelial cell has been proposed as a major source of injurious reactive oxygen species. This study was undertaken in an effort to understand the regulation of xanthine dehydrogenase (XDH)/XO expression at both the activity and gene expression levels in the epithelial cell under conditions associated with the inflammatory response. The results indicate that TNF, IFN-gamma, IL-6, IL-1, and dexamethasone induce XDH/XO activity in bovine renal epithelial cells (MDBK). This pattern of XDH/XO regulation by cytokines and steroids is analogous to the profile of response seen by acute phase reactants. Metabolic labeling and immunoprecipitation revealed the increase in XDH/XO activity requires new protein synthesis. By Northern analysis, all cytokines and dexamethasone increased the level of the 5-kb XDH/XO mRNA. This increase was not detectable in the presence of actinomycin D but was further induced in the presence of cycloheximide, consistent with the major site of XDH/XO up-regulation occurring at the transcriptional level. XDH/XO mRNA was very stable, with no indication that the rates of transcript degradation contributed to differences in mRNA accumulation or ultimate activity levels. In addition to providing information on the regulation of XDH/XO, the data presented furthers the understanding of the epithelial cell's potential to actively respond to immunomodulators associated with injury/inflammation.
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