Abstract
The induction of alpha 1-acid glycoprotein mRNA by recombinant murine interleukin-1, recombinant human interleukin-1 alpha, and recombinant human interleukin-1 beta has been studied in the rat hepatoma cell line Fao. Whereas the stimulatory capacities of recombinant human interleukin-1 alpha and recombinant murine interleukin-1 were almost identical, the concentrations of recombinant human interleukin-1 beta needed for half-maximal induction of alpha 1-acid glycoprotein mRNA were lower by three orders of magnitude. A 60-fold increase in alpha 1-acid glycoprotein mRNA levels was observed 18 h after the addition of recombinant interleukin-1 beta. In parallel albumin mRNA levels decreased to about 30%. The alpha 1-acid glycoprotein mRNA induction was strictly dependent on the presence of dexamethasone. For a full stimulation dexamethasone concentrations of greater than 10(-7) M were needed, whereas concentrations of less than 10(-12) M were ineffective. The increase in alpha 1-acid glycoprotein mRNA after recombinant human interleukin-1 beta was followed by a 36-fold stimulation in alpha 1-acid glycoprotein synthesis and secretion. When protein synthesis was blocked by either cycloheximide, puromycin, or emetine, the induction of alpha 1-acid glycoprotein mRNA by recombinant human interleukin-1 beta was impaired suggesting the involvement of a short-lived protein in the induction of alpha 1-acid glycoprotein mRNA.
Highlights
From the Bwchemisches Institut, Uniuersitat Freiburg, Hermann-Herder-Strasse 7, 0-7800 Freiburg and the SBlutspendezentraledes Deutschen Roten Kreuzes, Oberer Eselsberg0,7900 Ulm,Federal Republic of Germany
Cytoblotand mRNA Hybridization-Cells (5 X 105/well) were lysed in 10 mM Tris-HC1 buffer, pH 7.0, containing 1mM EDTA, and 1% Nonidet P-40, nuclei were removed bycentrifugation, the cytoplasmic RNA was denatured in the presence of formaldehyde essentially as described by White and Bancroft [40],and RNA was blotted to a gene screen membrane using a Manifold dot-blot apparatus mRNA levels (Fig. 1B).Dose-dependentdecreases were found for rhI1-la or p as well as for rm11-1
We examined the to the hepatoma cell cultures the activities of the three 11-1 effect of the synthetic glucocorticoid analog dexamethasone preparations had been determined ian thymocyte costimula- for the induction of al-AGP mRNA by rhI1-1P
Summary
11-1, and recombinant human 11-la and p change albumin, and al-AGP mRNA levels in a well-differentiated rat hepatoma cell line to asimilar extent asi n vivo during experimental inflammation. Among the latter,drastic changes in the serum levels of acute-phase proteins are observed. In the rat a,-macroglobulin, al-acid glycoprotein (aI-AGP),’ and cysteine proteinaseinhibitorrepresent the major positive acute-phase reactants. Their serum levels are elevated between 10- and several hundred-fold during inflammation The increase in serum levels is preceded by an increase in.the respective mRNA levels [410]. A t the same time serumand mRNA levelsof the negative. The abbreviations used are: a,-AGP, orl-acid glycoprotein; 11-1, interleukin-1; rh11-la, recombinant human interleukin-la; rh, recombinant human interleukin-la; rm, recombinant murine interleukin-1
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