Upstream regions directing heart-specific expression of the GATA6 gene during mouse early development

The expression of murine transcription factor GATA6 is restricted to tissue s including the heart and gastrointestinal systems during embryogenesis, an d is maintained throughout postnatal life. We have characterized the 5' ups tream region (6.4 kb) of the mouse GATA6 gene, and identified two closely s paced transcription initiation sites. The flanking sequence lacks a typical TATA-box, and is rich in guanine and cytosine. The role of the 5' upstream region was examined using the lacZ reporter gene in transgenic mice. A con struct containing the 5' flanking sequence (4.9 kb), untranslated exon 1 an d 1.3 kb intron 1 could drive the gene expression in the embryonic and adul t heart regions, Weak expression was also observed in the stomach, liver, a nd bronchial arch in addition to the cardiac region, Deletion of the 5' ups tream region (similar to 1.2 kb) or intron 1 abolished all this expression, indicating that at least two cis-acting control elements are necessary for heart-specific expression of GATA6 in vivo.