title: Inhibition of macrophage protein kinase C-mediated protein phosphorylation by Leishmania donovani lipophosphoglycan.
abstract: The cell surface lipophosphoglycan (LPG) from Leishmania donovani promastigotes is a potent inhibitor of purified protein kinase C (PKC) activity in vitro. In this study, we have investigated the effect of LPG on the activation process of PKC in murine bone marrow-derived macrophages. The extent and kinetics of calcium ionophore A23187-induced [3H] phorbol dibutyrate binding to macrophages were not affected by LPG pretreatment or infection with either wild-type or LPG-deficient promastigotes, indicating no effect on the association of calcium-dependent PKC with the plasma membrane. In contrast, LPG inhibited the phosphorylation of both the PKC-specific VRKRTRLLR substrate peptide and MARCKS, and endogenous PKC substrate, in 1-oleoyl-2-acetyl-glycerol-stimulated macrophages. These observations provide direct evidence that LPG effectively inhibits PKC activity in intact macrophages. Finally, depletion of PKC rendered macrophages more permissive for the proliferation of L. donovani, suggesting that inhibition of PKC-dependent events contributes to the survival of this parasite within its host cell.
authors.affiliation: Department of Biochemistry, University of Kentucky Medical Center, Lexington 40536.
authors.forename: A
authors.initials: A
authors.lastname: Descoteaux
authors.forename: G
authors.initials: G
authors.lastname: Matlashewski
authors.forename: S J
authors.initials: SJ
authors.lastname: Turco
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000953:Antigens, Protozoan / Q000494:pharmacology*; D015152:Blotting, Northern; D000001:Calcimycin / Q000494:pharmacology; D002462:Cell Membrane / Q000378:metabolism; D004075:Diglycerides / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005260:Female; D006028:Glycosphingolipids / Q000302:isolation & purification / Q000494:pharmacology*; D066298:In Vitro Techniques; D047908:Intracellular Signaling Peptides and Proteins; D007893:Leishmania donovani / Q000472:pathogenicity*; D008262:Macrophage Activation / Q000187:drug effects*; D008264:Macrophages / Q000378:metabolism* / Q000648:ultrastructure; D008565:Membrane Proteins; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D000076250:Myristoylated Alanine-Rich C Kinase Substrate; D009842:Oligopeptides / Q000378:metabolism; D015240:Phorbol 12,13-Dibutyrate / Q000378:metabolism; D010766:Phosphorylation; D011493:Protein Kinase C / Q000187:drug effects*; D011506:Proteins / Q000378:metabolism*; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis; D012313:RNA / Q000032:analysis; D013997:Time Factors
chemical_list: D000953:Antigens, Protozoan; D004075:Diglycerides; D006028:Glycosphingolipids; D047908:Intracellular Signaling Peptides and Proteins; C000619711:Marcks protein, mouse; D008565:Membrane Proteins; D009842:Oligopeptides; D011506:Proteins; D016760:Proto-Oncogene Proteins c-fos; C008290:lipophosphonoglycan; D000076250:Myristoylated Alanine-Rich C Kinase Substrate; C077534:valyl-arginyl-lysyl-arginyl-threonyl-arginyl-leucyl-leucyl-arginine; D015240:Phorbol 12,13-Dibutyrate; D000001:Calcimycin; D012313:RNA; C038237:1-oleoyl-2-acetylglycerol; D011493:Protein Kinase C