New putative control elements in the promoter of the gene for the CXCL13 chemokine, a target of the alternative NF-κB pathway

The proximal promoter region of the gene for the CXCL13/BLC chemokine has been studied by electrophoretic mobility shift assay and reporter gene analysis in order to detect new control elements, in particular, NF-kappa B binding sites. Two new putative control elements have been identified. One of them contains a Rel/NF-kappa B binding site and seems to participate in inducible gene expression. The other is an Sp1 factor binding site, essential for basal transcription. It is the first time that such a site is found in the promoter of a target gene of the alternative NF-kappa B pathway. This finding indicates that genes under the control of the alternative NF-kappa B pathway can be cooperatively regulated by Rel/NF-kappa B and Sp1. Our results will add to the understanding of the signaling pathways that govern the expression of genes controlled by the alternative NF-kappa B pathway.