Characterization of the structure and regulation of the murine gene encoding gut-enriched Kruppel-like factor (Kruppel-like factor 4)

Gut-enriched Kruppel-like factor (GKLF, KLF4) is an epithelial-specific tra nscription factor whose expression is associated with growth arrest, In ord er to understand the mechanisms regulating expression of the gene encoding GKLF, we isolated a genomic clone containing murine GKLF, The gene spans 5. 3 kb and contains four exons, A major start site of transcription was mappe d to an adenine residue 601 nt 5' of the translation initiation codon, An a dditional 1 kb of the 5'-flanking region was sequenced and found to contain multiple cis-elements homologous to the binding sites of several establish ed transcription factors including Sp1, AP-1, Cdx, GATA, and USF. In partic ular, three closely spaced GC-boxes 5' of the TATA box resemble the establi shed binding site for GKLF, DNase protection and electrophoretic mobility s hift assays verified that recombinant GKLF bound to each of the three GC-bo xes, In co-transfection experiments, GKLF transactivated a reporter gene li nked to the GKLF1 kb 5'-flanking region, as did Sp1, Sp3 and Cdx-2, Mutatio ns of one or both of the first and second GC-boxes in the promoter resulted in diminished transactivation by GKLF, These results demonstrate that the 5'-flanking sequence of the mouse GKLF gene functions as a promoter and is subject to autoregulation by its own gene product.