Characterization of the lung Kruppel-like transcription factor gene and upstream regulatory elements

We previously described the isolation and characterization of the cDNA for lung Kruppel-like factor (LKLF), a zinc finger transcription factor that is predominately expressed in the lung of adult mice. In this study, we report the complete structure and nucleotide sequence of the mouse LKLF gene, which is comprised of three exons and two small introns. Moreover, the identification of critical sequence elements required for expression is described using reporter constructs with the LKLF promoter transfected into LA-4 lung cells. Results from these constructs reveal an important region for transcriptional activity that lies between the -490/-72 bp upstream sequence. This region contains two canonical Spl binding sites that affect expression levels in a non tissue-specific manner. In addition, using a base-pair mutagenesis strategy, a region from -157/-72 bp was found to be necessary for upregulating expression. In transfection assays, mutations of the -138/-111 bp region resulted in approximately 70-80% loss of promoter activity. This cis-element does not appear to correspond to any known transcription factor consensus sequence. Moreover, mutations within this cis-region disrupt the binding of a protein complex from nuclear extracts of various tissues. (C) 1999 Elsevier Science B.V. All rights reserved.