Dr. Davis proposes to isolate cDNA and genomic clones containing structural information for the several known rat phosphodiesterases (PDEs). Two such genomic clones have already been identified using the cloned drosophila gene as a hybridization probe. Once the rat sequences are known, isozyme specific regions will be selected for probes for in situ localization of mRNAs in the rat brain, and for characterization of processed forms of the messages. High titer antisera will also be prepared and then used immunocytochemistry of the rat brain. Finally, mouse/hamster hybrid cell lines will be tested with the probes to establish the chromosomal locations of the cognate mouse PDE genes. Since their discovery by Sutherland, cyclic nucleotides have been shown to play a central role in the regulation of cell metabolism in virtually all organisms. As a result, the regulation of the enzymes that produce (cyclases) and degrade (PDEs) these compounds has continued to be a subject of great importance. Considerable evidence, both direct and indirect, points to important roles for the different PDEs in various functions of the mammalian brain (for example, vision and memory). As yet, however, there is little information about the number of PDE genes, about their regulation, and about the localization and eventual fate of their products in the brain. The proposed work will provide the tools needed to provide this information.
