US3 protein kinase of HSV-1 cycles between the cytoplasm and nucleus and interacts with programmed cell death protein 4 (PDCD4) to block apoptosis.

The U(S)3 protein kinase of herpes simplex virus 1 plays a key role in blocking apoptosis induced by viral gene products or exogenous agents. The U(S)3 protein kinase is similar to protein kinase A with respect to substrate range and specificity. We report that in the yeast two-hybrid system a domain of U(S)3 essential for antiapoptotic activity reacted with programmed cell death protein 4 (PDCD4). We report that U(S)3 interacts with PDCD4, that PDCD4 is posttranslationally modified in infected cells both in a U(S)3-dependent and -independent fashion, and that depletion of PDCD4 by siRNA blocked apoptosis induced by a Δα4 mutant virus. In infected cells, PDCD4 accumulates in the nucleus, whereas U(S)3 accumulates in the cytoplasm. Studies designed to elucidate the convergence of these proteins led to the discovery that U(S)3 protein kinase cycles between the nucleus and cytoplasm and that U(S)3 retains PDCD4 in infected cell nuclei.

Recombinant yeast screen for new inhibitors of human acetyl-CoA carboxylase 2 identifies potential drugs to treat obesity.

Acetyl-CoA carboxylase (ACC) is a key enzyme of fatty acid metabolism with multiple isozymes often expressed in different eukaryotic cellular compartments. ACC-made malonyl-CoA serves as a precursor for fatty acids; it also regulates fatty acid oxidation and feeding behavior in animals. ACC provides an important target for new drugs to treat human diseases. We have developed an inexpensive nonradioactive high-throughput screening system to identify new ACC inhibitors. The screen uses yeast gene-replacement strains depending for growth on cloned human ACC1 and ACC2. In "proof of concept" experiments, growth of such strains was inhibited by compounds known to target human ACCs. The screen is sensitive and robust. Medium-size chemical libraries yielded new specific inhibitors of human ACC2. The target of the best of these inhibitors was confirmed with in vitro enzymatic assays. This compound is a new drug chemotype inhibiting human ACC2 with 2.8 muM IC(50) and having no effect on human ACC1 at 100 muM.