B cell activation by synthetic lipopeptide analogues of bacterial lipoprotein bypassing phosphatidylinositol metabolism and proteinkinase C translocation.
Synthetic analogues of bacterial lipoprotein induce proliferation of murine small resting B lymphocytes. We investigated the role of proteinkinase C (PKC) activation in lipopeptide-induced B cell stimulation. Using a standardized extraction procedure, there was no change in membrane bound and soluble PKC activity upon stimulation with lipopeptide. However, omitting Ca2+ chelators from the standard extraction medium resulted in a decrease of membrane bound PKC activity after stimulation. Lipopeptide failed to induce phosphoinositide degradation and the generation of the two second messengers cAMP and cGMP. To test whether guanosinetriphosphate-binding proteins are involved in lipopeptide-induced signal transfer we investigated the effect of LiCl, choleratoxin and pertussistoxin on B lymphocyte proliferation. LiCl and pertussistoxin did not inhibit cell activation, whereas choleratoxin reduced the proliferation rate at concentrations higher than 0.5 micrograms/ml. Similar results were observed when LPS was used as mitogen, whereas the anti-immunoglobulin-induced B cell activation was inhibited by all three compounds. Our results show, that B cell activation by bacterial lipopeptides bypasses phosphatidylinositol metabolism and PKC translocation.
Steffens
U
U
Institut für Immunobiologie der Universität Freiburg, F.R.G.
Bessler
W
W
Hauschild
S
S
D000595:Amino Acid Sequence; D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002614:Chelating Agents / Q000494:pharmacology; D006801:Humans; D007295:Inositol Phosphates / Q000378:metabolism; D008074:Lipoproteins / Q000276:immunology*; D008213:Lymphocyte Activation; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D010716:Phosphatidylinositols / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism*; D015398:Signal Transduction
D002614:Chelating Agents; D007295:Inositol Phosphates; D008074:Lipoproteins; D010716:Phosphatidylinositols; C061110:N-palmitoyl-5,6-dipalmitoylcysteinyl-alanyl-glycine; D011493:Protein Kinase C; D002118:Calcium