NUCLEAR FACTOR INTERLEUKIN-6 MOTIFS MEDIATE TISSUE-SPECIFIC GENE-TRANSCRIPTION IN HYPOXIA

Activation of transcription at the nuclear factor interleukin 6 (NF-IL -6) DNA binding motif modulates expression of multiple genes important in host adaptive and developmental mechanisms. Studies showing that h ypoxia-induced transcription of IL-6 in cultured endothelial cells was due to transcriptional activation by the NF-IL-6 motif in the promote r (Yan, S.-F., Tritto, I., Pinsky, D., Liao, H., Huang, J., Fuller, G. , Brett, J., May, L., and Stern, D. (1995) J. Biol. Chem. 270, 11463-1 1471) led us to prepare transgenic mice using 115- or 14-base pair reg ions of the promoter encompassing the NF-IL-6 site ligated to the lacZ reporter gene and the basal thymidine kinase promoter. On exposure to hypoxia or induction of ischemia, mice bearing either of the construc ts showed prominent expression of the transgene in lung and cardiac va sculature and in the kidney but not in the liver (parenchyma or vascul ature). In contrast, transgenic mice bearing a mutationally inactivate d NF-IL-6 site showed no increase in transgene expression in hypoxia. Gel retardation assays revealed time-dependent, hypoxia-enhanced nucle ar binding activity for the NF-IL-6 site in nuclear extracts of the he art, lung, and kidney but not in the liver; the hypoxia-enhanced band disappeared on addition of antibody to C/EBP beta-NF-IL-6. Consistent with the specificity of hypoxia-mediated activation of C/EBP beta-NF-I L-6, gel retardation assays showed no change in the intensity of the h ypoxia-enhanced gel shift band in the presence of excess unlabeled oli gonucleotide probes or antibodies related to other transcription facto rs, including NF kappa B, AP1, cAMP response element-binding protein, SP1, and hypoxia-inducible factor 1. These data indicate that the tran scription factor NF-IL-6 is sensitive to environmental oxygen deprivat ion, and the tissue-specific pattern of gene expression suggests that local mechanisms have an important regulatory effect.