Cloning, characterization, and tissue distribution of mouse phosphodiesterase 7A1

We have cloned a cDNA representing mouse phosphodiesterases (PDE) 7A1. The open reading frame encodes a protein of 482 amino acids with a predicted mo lecular mass of 55417. Like human PDE7A variants, mouse PDE7A1 and A2 are 5 ' splice variants from a common gene. The distinct N-terminal sequence of m ouse PDE7A1 is highly homologous to the corresponding sequence of human PDE 7A1 with a similarity of 98% but not to that of mouse PDE7A2 (with a simila rity of 12%), and is more hydrophilic than that of mouse PDE7A2. Mouse PDE7 A1 expressed in SF9 cells has been compared with human PDE7A1 under identic al conditions. Mouse PDE7A1 has a Km for cAMP of 0.2 mu M, an optimal pH of 7.5, an IC50 value of 14 mu M for 3-isobutyl-1-methylxanthine (IBMX), and is dependent on Mg2+ for activity. All these characteristics are very simil ar to those of human PDE7A1. In mice, PDE7A1 is expressed in tissues of the immune system (lymph node, thymus, spleen, and blood leukocyte), testis, b rain, kidney and lung but not in skeletal muscle, heart, embryo, or liver, while PDE7A2 is expressed in skeletal muscle, heart, embryo, and kidney, bu t not in the other tissues. This tissue distribution profile is very simila r to that in humans, and hence suggests that PDE7A1 and 7A2 might play a si milar role in different species. (C) 2000 Academic Press.