A 3.4-kb fragment on the 5' side of the ANF gene promoted significant transcription in atrial but not ventricular cardiocytes from 1-day-old rats, with 2.4 kb sufficient for high-level expression.
Nucleotide sequences necessary to direct transcription of the gene encoding atrial natriuretic factor (ANF) in neonatal and fetal hearts have been defined by using expression of the prokaryotic marker gene chloramphenicol acetyltransferase (CAT) as a functional assay. Hybrid ANF-CAT genes were introduced into primary cultured cardiocytes by electroporation. A 3.4-kilobase (kb) fragment containing sequences on the 5' side of the ANF gene promoted significant CAT activity in atrial but not ventricular cardiocytes derived from 1-day-old rats. Deletion analysis of putative regulatory regions demonstrated that 2.4 kb of 5' ANF sequences were sufficient for high-level atrial transcription, whereas hybrid genes containing less than 700 base pairs of ANF sequences promoted less CAT activity. Cardiocytes derived from embryonic ventricles expressed the 3.4-kb ANF-CAT hybrid gene at levels comparable to atrial cells, suggesting that the nucleotide sequences controlling developmental regulation of ANF expression are contained in this 5' region. Nucleotide sequence analysis of this 3.6-kb region identified segments that may contribute to the regulated expression of the ANF gene.
Seidman et al. (Wed,) conducted a other in Atrial natriuretic factor gene expression. Hybrid ANF-CAT genes (3.4-kb fragment) vs. Hybrid genes containing less than 700 base pairs of ANF sequences was evaluated on CAT activity (functional assay for transcription). A 3.4-kb fragment on the 5' side of the ANF gene promoted significant transcription in atrial but not ventricular cardiocytes from 1-day-old rats, with 2.4 kb sufficient for high-level expression.