The
CXC chemokine,
melanoma growth stimulatory activity/growth-regulated
protein, CXCL1 is an important modulator of
inflammation, wound healing, angiogenesis, and
tumorigenesis. Transcription of CXCL1 is regulated through several cis-acting elements including Sp1,
NF-kappa B, and an
element that lies immediately upstream of the
NF-kappa B element, the immediate upstream region (IUR). A transcription
element data base search indicated that the IUR
element contains a binding site for the transcriptional repressor, human CUT
homeodomain protein/CCAAT displacement
protein (
CDP). It is shown here that in electrophoretic mobility shift assays, complexes obtained with the IUR
oligonucleotide probe are supershifted by anti-
CDP antibodies and that a
CDP polypeptide containing a high affinity
DNA binding domain binds to the sequence GGGATCGATC in the IUR
element. In Southwestern blot analyses,
oligonucleotides containing the wild-type IUR sequence, but not a mutant
oligonucleotide with substitutions in the GGGATCGATC sequence, bind a 170--180-kDa
protein. Furthermore, overexpression of the
CDP protein blocks CXCL1 promoter activity in reporter gene assays, whereas overexpression of an antisense
CDP construct leads to a significant increase in CXCL1 promoter activity. Mutations in the IUR
element, which map in the putative
CDP-binding site, inhibit the binding of
CDP to the IUR
element and favor increased transcription from the CXCL1 promoter. Based on these results, we propose that transcriptional regulation of the CXCL1 gene is mediated in part by
CDP, which could play an important role in inflammatory processes and
tumorigenesis.