Identification of a novel regulatory region in the interleukin-6 gene promoter

Interleukin-6 (IL6) is an important pleiotropic cytokine that is regulated at the transcriptional level. To date, most work on its regulation has focused on a 1.2 kb region 5' from the start of transcription, similar to published reports on other cytokine genes. This report demonstrates for the first time that a cytokine gene can be regulated by cis-acting regions much further upstream than previously examined. Comparative genomic analysis showed that a 120 kb region contains blocks of sequence conservation between human and rodent genomes, and that a 15 kb region proximal to the start of transcription contains 10 highly homologous sequence blocks of between 100 and 250 bp. By means of a reporter gene assay, a novel transcriptionally active region located between -5307 and -5202 bp upstream from the start of transcription was identified. Electrophoretic mobility shift assays showed nuclear protein(s) binding to this region, thus raising the possibility that the regulatory activity shown by the reporter gene constructs may be mediated by these proteins. These results suggest that the regulation of IL6 expression involves a much larger upstream region than previously examined and the control of 116 transcription is likely to be regulated by a complex mechanism of modular cis-regulatory elements. (C) 2008 Elsevier Ltd. All rights reserved.