TY - JOUR
T1 - Docosahexaenoic acid decreases IRF-1 MRNA and thus inhibits activation of both the IRF-E and NFκd response elements of the iNOS promoter
AU - Kielar, Mariusz L.
AU - Jeyarajah, D. Rohan
AU - Penfield, Jeffery G.
AU - Lu, Christopher Y.
PY - 2000/5/27
Y1 - 2000/5/27
N2 - Background. Nitric oxide produced by inducible nitric oxide synthase (iNOS) may be cytotoxic during cardiac, hepatic, and renal acute allograft rejection. Because the incidence of rejection is decreased by fish oils that contain docosahexaenoic acid (DHA), we investigated the effects of DHA on iNOS. Using nuclear run-on assays and iNOS-promoter constructs, we previously showed that docosahexaenoic acid (DHA) inhibits activation of the iNOS gene by murine macrophages that had been stimulated in vitro by IFNγ plus lipopolysaccharide. Methods. In our current investigation, our purpose has been to determine how DHA inhibits iNOS gene activation in murine macrophages, by using gel retardation and Northern blotting techniques. We studied the effects of DHA on the formation nuclear protein complexes that interact with the critical iNOS promoter's response elements for IRF-1 (IRF- E-923 to -913 bp) and NF-κB (NFκd -85 to -75 bp). Results. We now show that DHA inhibited increases of IRF-1 mRNA abundance in response to IFNy plus lipopolysaccharide. As expected, we found that this prevented formation of the nuclear protein complex that hinds to the IRF-E DNA response element. We also found that inhibition of IRF-1 inhibited formation of the nuclear protein complex that binds to the NFkd DNA response element. Conclusions. DHA decreases the abundance of IRF-1 mRNA in stimulated cells. That, in turn, results in the decreased nuclear protein binding to the major iNOS promoter response elements (IRF-E and NF-κB). We found that this occurred because IRF-1 is a component of both the nuclear protein complex that binds to IRF-E and the nuclear protein complex that binds to NFκd.
AB - Background. Nitric oxide produced by inducible nitric oxide synthase (iNOS) may be cytotoxic during cardiac, hepatic, and renal acute allograft rejection. Because the incidence of rejection is decreased by fish oils that contain docosahexaenoic acid (DHA), we investigated the effects of DHA on iNOS. Using nuclear run-on assays and iNOS-promoter constructs, we previously showed that docosahexaenoic acid (DHA) inhibits activation of the iNOS gene by murine macrophages that had been stimulated in vitro by IFNγ plus lipopolysaccharide. Methods. In our current investigation, our purpose has been to determine how DHA inhibits iNOS gene activation in murine macrophages, by using gel retardation and Northern blotting techniques. We studied the effects of DHA on the formation nuclear protein complexes that interact with the critical iNOS promoter's response elements for IRF-1 (IRF- E-923 to -913 bp) and NF-κB (NFκd -85 to -75 bp). Results. We now show that DHA inhibited increases of IRF-1 mRNA abundance in response to IFNy plus lipopolysaccharide. As expected, we found that this prevented formation of the nuclear protein complex that hinds to the IRF-E DNA response element. We also found that inhibition of IRF-1 inhibited formation of the nuclear protein complex that binds to the NFkd DNA response element. Conclusions. DHA decreases the abundance of IRF-1 mRNA in stimulated cells. That, in turn, results in the decreased nuclear protein binding to the major iNOS promoter response elements (IRF-E and NF-κB). We found that this occurred because IRF-1 is a component of both the nuclear protein complex that binds to IRF-E and the nuclear protein complex that binds to NFκd.
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U2 - 10.1097/00007890-200005270-00030
DO - 10.1097/00007890-200005270-00030
M3 - Article
C2 - 10852612
AN - SCOPUS:0034720546
SN - 0041-1337
VL - 69
SP - 2131
EP - 2137
JO - Transplantation
JF - Transplantation
IS - 10
ER -