Rottlerin-independent attenuation of pervanadate-induced tyrosine phosphorylation events by protein kinase C-delta in hemopoietic cells.
The understanding and control of many pathophysiological conditions is based on knowledge of subtly regulated intracellular signaling networks. We have found that in pervanadate (PV)-treated J558L myeloma cells, amongst other signaling proteins, protein kinase C (PKC)-delta and src homology 2-containing inositol phosphatase (SHIP) are tyrosine phosphorylated on expression of the B cell receptor, suggesting a role for these proteins in the preformed B cell receptor transducer complex. Rottlerin, a widely used PKC-delta-specific inhibitor, efficiently blocks these PV-induced tyrosine phosphorylation events. Furthermore, PV treatment of bone marrow-derived mast cells (BMMC) also results in tyrosine phosphorylation of PKC-delta, SHIP, and additional proteins. Rottlerin also inhibits these responses, indicating that PKC-delta might play an important enhancing role in the propagation of phosphotyrosine signals in B cells and mast cells and hence in the regulation of function of both cell types. Therefore, BMMC from PKC-delta -/- mice were generated by in vitro differentiation and assayed for tyrosine phosphorylation events in response to PV. Intriguingly, and opposite to the Rottlerin data, PKC-delta -/- BMMC show a stronger response to PV than wild-type cells, suggesting an attenuating role for PKC-delta. This response can be inhibited equally well by Rottlerin, indicating clearly that Rottlerin is not specific for PKC-delta in vivo. A comparison between Rottlerin and the panspecific PKC inhibitor bisindolylmaleimide suggests that Rottlerin also targets kinases beyond the PKC family. Moreover, Ser473 phosphorylation of protein kinase B (PKB) after PV treatment is blocked by Rottlerin as efficiently as by the phosphatidylinositol 3-kinase inhibitor LY294002. In this report, we provide evidence that PKC-delta constitutes a crucial attenuating factor in B cell and mast cell signal transduction and suggest that PKC-delta is important for the regulation of physiological B and mast cell functions as well as for their pathophysiology. Furthermore, dominant PKC-delta-independent effects of Rottlerin are presented, indicating restrictions of this inhibitor for use in signal transduction research.
Leitges
M
M
Max Planck Institute for Experimental Endocrinology, Hannover, Germany.
Elis
W
W
Gimborn
K
K
Huber
M
M
D000098:Acetophenones / Q000494:pharmacology*; D000818:Animals; D001402:B-Lymphocytes / Q000187:drug effects / Q000276:immunology; D001578:Benzopyrans / Q000494:pharmacology*; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006412:Hematopoietic Stem Cells / Q000166:cytology; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D008407:Mast Cells / Q000737:chemistry / Q000187:drug effects / Q000276:immunology; D051379:Mice; D018345:Mice, Knockout; D000072183:Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D051745:Protein Kinase C-delta; D017027:Protein Tyrosine Phosphatases / Q000037:antagonists & inhibitors; D017455:Receptors, IgE / Q000032:analysis; D014407:Tumor Cells, Cultured; D014638:Vanadates / Q000494:pharmacology*
D000098:Acetophenones; D001578:Benzopyrans; D004791:Enzyme Inhibitors; D007527:Isoenzymes; D017455:Receptors, IgE; C076715:pervanadate; D019000:Phosphotyrosine; D014638:Vanadates; C085746:rottlerin; C497259:Prkcd protein, mouse; D011493:Protein Kinase C; D051745:Protein Kinase C-delta; D010744:Phosphoric Monoester Hydrolases; D017027:Protein Tyrosine Phosphatases; C098706:INPPL1 protein, human; D000072183:Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases