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G protein-coupled receptors mediate their biological responses through the generation of second messengers, such as cAMP. The down-regulation of their activity (desensitization) is carried out, in part, by the family of G protein-coupled receptor kinases, which phosphorylate activated receptors. The Gprk2 gene in Drosophila melanogaster is a putative member of this family. The GPRK2 protein is expressed most abundantly in the ovaries and in the mushroom bodies, the brain region that is implicated in learning and memory in insects. Many of the genes that are involved in learning in Drosophila are members of a cAMP-signaling pathway and are also expressed in the mushroom bodies. These observations suggest that the Gprk2 gene may be involved in a cAMP-mediated pathway. To investigate this possibility, we tested for a genetic interaction between Gprk2 and dunce (which encodes cAMP-specific phosphodiesterase). A mutant allele of Gprk2, called gprk2(6936), has decreased fertility as a result of reduced levels of egg laying and hatching, and developing egg chambers display defects in the formation of anterior structures. Similarly, many alleles of dunce are sterile, with an ovary phenotype that resembles gprk2(6936). Introduction of a single copy of a hypomorphic or null allele of dunce into the gprk2(6936) background suppressed all of these defects to a significant degree. Suppression was also observed when a single copy of gprk2(6936) was introduced into a dunce background. Like mutants of rutabaga (which encodes a calcium/calmodulin-dependent adenylate cyclase), gprk2(6936) has reduced levels of cAMP. Ovaries from gprk2(6936) females contain about one third of the normal amount of cAMP. In addition, in every mutant combination where fertility is increased, cAMP levels are closer to wild type levels. These results suggest that Gprk2 is functioning in a cAMP-signaling pathway and that the underlying basis of the interaction between Gprk2 and dunce is a normalization of cAMP levels., (Copyright 2001 Academic Press.)

Interleukin-12 is proposed to have anti-neoplastic activity on the basis of both its anti-angiogenic and immunologic effects. Gene gun therapy with interleukin-12 cDNA into the peritumoral area of immunocompetent 129/J mice with life-threatening primary vascular tumors reduced tumor volume 7.5-fold and almost tripled the duration of mouse survival, in contrast with luciferase-bombarded control mice. Epidermal expression of mouse interleukin-12 elevated tumoral and serum levels of interferon-gamma and tumor necrosis factor-alpha, increased the tumoral populations of T lymphocyte and natural killer cells, and induced tumor apoptosis. Gene transfer of interleukin-12 had little effect on tumor volumes and survival of tumor-bearing athymic nude mice, emphasizing the requirement for T cell directed cellular immunity. Peritumoral gene gun introduction of interleukin-12 may be a novel, cost-effective approach to limit the growth and associated mortality of life-threatening tumors.