ISSN:
0021-9541
Keywords:
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Medicine
Notes:
Treatment with 12-O-tetradecanoyl-phorbol-13-acetate (TPA) and incubation with lipopolysaccharide (LPS) induces Interleukin 1β (IL-1β) production in the histiocytic lymphoma cell line U937. Here we investigated the effect of treatment with both TPA and 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3) on LPS-induced IL-1β production in U937 cells. To clarify the mechanism of IL-1β production, the possible role of polyamines in this process was examined. Combined treatment with TPA and 1,25(OH)2D3 for 72 h followed by incubation with LPS for 24 h caused synergistic induction of both IL-1β release and mRNA expression. On the other hand, TPA increased the numbers of vitamin D3 receptors, which may be one mechanism of this synergistic induction. Ornithine decarboxylase (ODC), a rate-limiting enzyme for polyamine biosynthesis, was also induced by these compounds biphasically: the first peak of ODC activity was observed at 4 h of the incubation with the two compounds and the second peak was at 4 h after the addition of LPS. To find whether these peaks were related to IL-1β production, DL-α-difluoromethylornithine (DFMO), a specific irreversible inhibitor of ODC, was added together with TPA and 1,25(OH)2D3. DFMO decreased the cellular levels of putrescine and spermidine and suppressed IL-1β release and IL-1β mRNA expression by 65%. Exogenous putrescine, but not spermidine, abrogated these kinds of inhibition. Similar results were obtained with DFMO and the polyamines during the differentiation of the cells up to the monocyte or macrophage stage. These results thus suggest that changes in either of these intracellular polyamines, especially putrescine, help to regulate the differentiation of U937 cells, resulting in partial control of the regulation of IL-1β production.
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jcp.1041470203
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