PREFERENTIAL EXPRESSION IN MUSHROOM BODIES OF THE CATALYTIC SUBUNIT OF PROTEIN KINASE-A AND ITS ROLE IN LEARNING AND MEMORY

Involvement of the cAMP cascade in Drosophila learning and memory is s uggested by the aberrant behavioral phenotypes of the mutants dunce (c AMP phosphodiesterase) and rutabaga (adenylyl cyclase). Line DCO581, i solated via an enhancer detector screen for genes preferentially expre ssed in the mushroom bodies, contains a transposon in the first exon o f the catalytic subunit gene (DCO) of protein kinase A (PKA). RNA in s itu hybridization and immunohistochemistry show that DCO is preferenti ally expressed in the mushroom bodies. The DCO581 insertion and an ind ependently isolated hypomorphic allele (DCO(B10)) each produce homozyg ous lethality and a 40% decrease in PKA activity in heterozygotes. Thi s decrease has mild effects on learning but no effect on memory. Howev er, the 80% reduction in activity obtained by constructing heteroallel ic yet viable DCO581/DCO(B10) animals results in a dramatic learning a nd memory deficit. These results suggest that PKA plays a crucial role in the cAMP cascade in mushroom bodies to mediate learning and memory processes.