Cardiac type cGMP-inhibited phosphodiesterase (PDE3A) gene structure: Similarity and difference to adipocyte type PDE3B gene

Phosphodiesterase type 3 isoforms, PDE3A and 3B, are expressed primarily in cardiovascular and adipose tissues, respectively. We previously reported a shorter transcript of 4.4-kb PDE3A which is predominantly transcribed in h uman placenta, whereas a full-length 7.6-kb transcript corresponding to the cardiac PDE3A cDNA has not been characterized. Due to unfortunate circumst ances created by changes in PDE3 nomenclature, PDE3B gene structure previou sly reported used PDE3A in its title. Here, we describe PDE3A gene structur e, which comprises 16 exons spanning over 130 kb on chromosome 12p12. Two P DE3 isoforms share similar gene organization, but localize to different chr omosomes. The most distal transcription initiation site of the PDE3A gene i s similar to 1071 bases upstream of the ATG: site, suggesting that exon 1 c onsists of 1071 and 960 bp of untranslated and translated sequences, respec tively. The proximal 5'-flanking region, which does not contain TATA-like s equences, exhibited weak but significant promoter activity. Results suggest potential involvement of distal promoter/enhancer and translational regula tion for expression of the 7.6-kb transcript. (C) 2000 Academic Press.