Distribution of cytochrome P450 1A1 and NADPH-cytochrome P450 reductase in lungs of rabbits treated with 2,3,7,8-tetrachlorodibenzo-p-dioxin: ultrastructural immunolocalization and in situ hybridization
Induction of cytochrome P450 1A1 (P450 1A1) in a variety of tissues is a well established consequence of exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related compounds. Although localization of the induced protein within the lung has been described, the precise intracellular distributi...
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Veröffentlicht in: | Molecular pharmacology 1992-06, Vol.41 (6), p.1039-1046 |
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Zusammenfassung: | Induction of cytochrome P450 1A1 (P450 1A1) in a variety of tissues is a well established consequence of exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin
(TCDD) and related compounds. Although localization of the induced protein within the lung has been described, the precise
intracellular distribution of the enzyme is not clear. Analysis of tissue sections, microsomal proteins, and mRNA from lungs
of treated and untreated rabbits established that P450 1A1 had been induced by treatment with TCDD. Rabbit lungs from animals
treated with TCDD were examined with immunocytochemistry and in situ hybridization, to identify the cell types that contain
P450 1A1 and those that contain mRNA encoding P450 1A1. Endothelial cells of the entire vascular bed of rabbit lung reacted
markedly with anti-P450 1A1. Likewise, cells lining both arteries and veins, as well as capillary endothelial cells, reacted
strongly with the cDNA probe for mRNA encoding P450 1A1. Clara cells at all levels of airway labeled prominently for both
P-450 1A1 and P450 1A1 mRNA. In addition, type 2 cells, alveolar macrophages, and to a lesser degree, ciliated cells reacted
with the cDNA probe. P450 reductase, which is required for P450 activity, has previously been identified in Clara cells, type
2 cells, and alveolar macrophages, but not in endothelium of rabbit lung. We have now obtained similar results for the localization
of mRNA encoding P-450 reductase. This finding brings into question the function of P450 1A1 in endothelium. |
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ISSN: | 0026-895X 1521-0111 |