B cell triggering by bacterial lipopeptide involves both translocation and activation of the membrane-bound form of protein kinase C.
B cell activation by the lipopeptide trispalmitoyl-cysteinyl-alanyl-glycine (TPP), the biologically active moiety of bacterial lipoprotein, results in protein kinase C (PKC) translocation from the cytosol to the plasma membrane, as well as a significant increase in the activity of membrane-associated PKC that can be observed by in vitro incubation with TPP of partially purified PKC at calcium concentrations in the range of those prevailing in unstimulated B cells. TPP does not affect either the phosphoinositide turnover or the cytosolic-free calcium concentration, but promotes an increase in the intracellular pH that can be blocked by the PKC-inhibitors staurosporine or H-7. Moreover, incubation of B cells with staurosporine suppressed the proliferative response promoted by TPP at a half-maximum effective dose of 16 nM. Activation by TPP of PKC isoenzymes resolved after hydroxylapatite chromatography revealed that the resulting beta I/beta II isoenzyme was more sensitive than the alpha isoenzyme. These results suggest that TPP might mediate B cell activation via interaction with the membrane-associated fraction of PKC.
Boscá
L
L
Instituto de Bioquimica, Facultad de Farmacia, Universidad Complutense, Madrid, Spain.
Márquez
C
C
Martínez
C
C
D000818:Animals; D001402:B-Lymphocytes / Q000187:drug effects* / Q000201:enzymology / Q000276:immunology; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000502:physiology; D002462:Cell Membrane / Q000201:enzymology; D004789:Enzyme Activation; D007527:Isoenzymes / Q000502:physiology; D008074:Lipoproteins / Q000494:pharmacology*; D008213:Lymphocyte Activation / Q000187:drug effects*; D051379:Mice; D008807:Mice, Inbred BALB C; D011493:Protein Kinase C / Q000502:physiology*; D013601:T-Lymphocytes / Q000201:enzymology
D007527:Isoenzymes; D008074:Lipoproteins; C061110:N-palmitoyl-5,6-dipalmitoylcysteinyl-alanyl-glycine; D011493:Protein Kinase C; D002118:Calcium