Characterrization of cardiac specific specific homebox gene

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We have isolated human cardiac specific homeobox-containing gene, CSX.To elucidate the molecular mechanism of cardiac development, we examined upstream and downstream genes of CSX.1. Characterization of upstream genesCSX gene is composed of two exons and one intron. Three isoforms of CSX are derived from one CSX gene by the alternative splicing mechanism. -1 kb promoter sequence of CSX was enough to abundantly express CSX gene in cardiac myocytes and especially 20bp sequences around-110 bp region were important. There were some proteins which bound to these sequences.2. Characterization of downstream genesAmong many genes which are expressed in cardiac myocytes, CSX activated transcription of atrial natriuretic peptide (ANP) and brain creatine kinase genes. There were two CSX binding sites in the promoter of ANP.3. Characterization of associated proteinsSince CSX synergistically activated transcription of ANP gene with a zinc finger protein, GATA4, we examined the protein-protein association between CSX and GATA4. Using GST pull down assay, we elucidated that CSX was associated with GATA4.