Mouse connexin37: gene structure and promoter analysis

Connexin37 (Cx37) is a subunit gap junction protein which exhibits limited expression in only a few cell types, predominantly in endothelial cells and in the lung. To begin to analyze Cx37 expression, we isolated a 1.6 kb mou se Cx37 cDNA from a mouse lung cDNA library and isolated corresponding mous e genomic clones from a bacterial artificial chromosome library. Sequencing and comparison of these clones showed that the Cx37 gene contained a short first exon, an 1.0 kb single intron and a second exon containing the compl ete coding region and 3'-untranslated region (UTR). The 5'-UTR of the mouse cDNA showed 70% identity to that of human Cx37. Primer extension experimen ts performed using mouse lung RNA gave two bands of sizes consistent with t he transcription start site predicted from the cDNA. Sequence analysis show ed that the regions flanking exon I contained a consensus 'TATA box' 43 bp 5' from the transcription start site preceded by several putative transcrip tion factor binding sites and a 282 bp truncated L1Md interspersed element. Luciferase reporter gene transfections suggested that an area of 268 bp 5' from the first exon acted as a basal promoter for Cx37 and that there was a strong negative regulatory element in the intron. (C) 2000 Elsevier Scien ce B.V. All rights reserved.