Interleukin 4 induces transcription of the 15-lipoxygenase I gene in human endothelial cells.
The reticulocyte-type 15-lipoxygenase (15-LO-I) has been implicated in atherogenesis because of its capability of oxidizing low density lipoprotein. Therefore, we investigated the expression of the 15-LO-I gene in human umbilical vein endothelial cells (HUVEC). Nonactivated HUVEC did not exhibit detectable 15-LO-I mRNA. However, exposure of the cells to interleukin 4 (IL-4) induced the transcription of the 15-LO-I gene in a time- and concentration-dependent manner. Interestingly, this induction was not paralleled by a concomitant production of the functional 15-LO-I enzyme, as indicated by activity assays and immunoblotting. To gain more information about the mechanism of the induction process, we investigated IL-4-dependent activation of nuclear transcription factors for which binding sites were previously identified in the 5'-flanking region of the human 15-LO-I gene. Electrophoretic mobility shift assays revealed that IL-4 can activate signal transducer and activator of transcription 6, activator protein 2, GATA motif-binding transcription factor 1, nuclear factor 1, and SP-1 in HUVEC in a time- and concentration-dependent manner. Activation of these transcription factors was observed as early as 30 min after cytokine exposure. These data indicate that IL-4 upregulates the transcription of the 15-LO-I gene in human vascular endothelial cells, and this process may involve the activation of several nuclear transcription factors. The lack of active 15-LO-I protein in the presence of functional 15-LO-I mRNA suggests additional regulatory elements of 15-LO expression at posttranscriptional levels.
Lee
Y W
YW
Department of Surgery, University of Kentucky Medical Center, Lexington, KY 40536, USA.
Kühn
H
H
Kaiser
S
S
Hennig
B
B
Daugherty
A
A
Toborek
M
M
D001093:Arachidonate 15-Lipoxygenase / Q000235:genetics* / Q000378:metabolism; D001161:Arteriosclerosis / Q000503:physiopathology; D022762:CCAAT-Enhancer-Binding Proteins / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D003513:Cycloheximide / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D050981:Erythroid-Specific DNA-Binding Factors; D005786:Gene Expression Regulation; D006801:Humans; D015151:Immunoblotting; D015847:Interleukin-4 / Q000494:pharmacology*; D051839:NFI Transcription Factors; D009687:Nuclear Proteins; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050800:STAT6 Transcription Factor; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D050656:Transcription Factor AP-2; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D051840:Y-Box-Binding Protein 1
D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins; D050981:Erythroid-Specific DNA-Binding Factors; D051839:NFI Transcription Factors; D009687:Nuclear Proteins; D011500:Protein Synthesis Inhibitors; D050800:STAT6 Transcription Factor; C494101:STAT6 protein, human; D015534:Trans-Activators; D050656:Transcription Factor AP-2; D014157:Transcription Factors; D051840:Y-Box-Binding Protein 1; C070856:YBX1 protein, human; D015847:Interleukin-4; D003513:Cycloheximide; D001093:Arachidonate 15-Lipoxygenase