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

The expression of murine transcription factor GATA6 is restricted to tissues including the heart and gastrointestinal systems during embryogenesis, and is maintained throughout postnatal life. We have characterized the 5' upstream region (6.4 kb) of the mouse GATA6 gene, and identified two closely spaced 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 construct containing the 5' flanking sequence (4.9 kb), untranslated exon 1 and 1.3 kb intron 1 could drive the gene expression in the embryonic and adult heart regions. Weak expression was also observed in the stomach, liver, and bronchial arch in addition to the cardiac region. Deletion of the 5' upstream region ( approximately 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.