title: Leishmania major: effect of protein kinase A and phosphodiesterase activity on infectivity and proliferation of promastigotes.
abstract: Effect of modulators on protein kinase A (PKA) activity, promastigote growth and their ability to infect peritoneal macrophages was monitored. PKA inhibitors reduced [Protein Kinase Inhibitor (PKI) - 56%; H89 - 54.5%] kemptide phosphorylation by Leishmania major promastigote lysates, while activators increased phosphorylation (8-CPT-cAMP - 88%; Sp-cAMPS-AM - 152%). Activation was specifically inhibited by PKI. Phosphodiesterase inhibitors also increased kemptide phosphorylation (dipyridamole - 171%; rolipram - 106%; and 3-isobutyl-1-methyl-xanthine - 154%). Parasite proliferation was significantly retarded (200 nM H89; 100 microM myristoylated-PKI) or completely inhibited (500 nM H89) by culturing with PKA inhibitors. Incubation with dipyridamole or Sp-cAMPS-AM also inhibited proliferation. Brief treatment (2h) with either H89, myristoylated-PKI, dipyridamole or Sp-cAMPS-AM reduced initial macrophage infection at days 1 and 2 (>40%) and on day 3 (>78% only for 100 microM myr-PKI). Characterization of leishmanial cAMP mediated signal transduction pathways will serve as the basis for the new drug design.
authors.affiliation: Kuvin Center for the Study of Infectious and Tropical Diseases, Department of Microbiology and Molecular Genetics, Hebrew University, Hadassah Medical School, Jerusalem 91120, Israel.
authors.forename: Laura
authors.initials: L
authors.lastname: Malki-Feldman
authors.forename: Charles L
authors.initials: CL
authors.lastname: Jaffe
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D018320:Leishmania major / Q000187:drug effects / Q000201:enzymology* / Q000254:growth & development*; D017737:Macrophages, Peritoneal / Q000469:parasitology; D051379:Mice; D009842:Oligopeptides / Q000378:metabolism; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D010727:Phosphoric Diester Hydrolases / Q000187:drug effects / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects
chemical_list: D009842:Oligopeptides; D010726:Phosphodiesterase Inhibitors; C037642:kemptide; D017868:Cyclic AMP-Dependent Protein Kinases; D010727:Phosphoric Diester Hydrolases