title: Modulation of cellular processes by H7, a non-selective inhibitor of protein kinases.
abstract: H7 has been described as a potent inhibitor of protein kinase C (PKC) and has been widely used to investigate the regulatory role of this enzyme in intact cell systems. In this comparative study between H7 and the microbial alkaloid, staurosporine, we found that the former inhibited rat brain PKC and cAMP dependent protein kinase with IC50 values of 18 and 16 microM respectively whereas the latter was a much more potent inhibitor of both kinases with IC50 values of 9.5 nM and 42 nM respectively. H7, at concentrations up to 100 microM, failed to block cellular events induced by phorbol esters, agents which specifically stimulate PKC, yet was a potent inhibitor of IL-2 induced T cell proliferation with an IC50 value of 19 microM. In contrast, staurosporine was a potent inhibitor of both phorbol ester induced p47 phosphorylation in platelet (I50 value = 540 nM) and also CD3 and CD4 down-regulation in T cells (I50 values 200 nM and 50 nM respectively). Staurosporine was also a potent inhibitor of IL-2 induced T cell proliferation I50 value = 9 nM). These results provide a strong argument against the use of H7 to probe for PKC involvement in cellular processes.
authors.affiliation: Research Centre, Roche Products Ltd, Welwyn Garden City, UK.
authors.forename: J S
authors.initials: JS
authors.lastname: Nixon
authors.forename: S E
authors.initials: SE
authors.lastname: Wilkinson
authors.forename: P D
authors.initials: PD
authors.lastname: Davis
authors.forename: A D
authors.initials: AD
authors.lastname: Sedgwick
authors.forename: J
authors.initials: J
authors.lastname: Wadsworth
authors.forename: D
authors.initials: D
authors.lastname: Westmacott
mesh_terms: D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D001921:Brain / Q000201:enzymology; D015704:CD4 Antigens / Q000378:metabolism; D000242:Cyclic AMP / Q000494:pharmacology; D015536:Down-Regulation; D007376:Interleukin-2 / Q000494:pharmacology; D007546:Isoquinolines / Q000494:pharmacology*; D008213:Lymphocyte Activation; D051379:Mice; D008970:Molecular Weight; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D010879:Piperazines / Q000494:pharmacology*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors*; D047428:Protein Kinase Inhibitors; D051381:Rats; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism; D019311:Staurosporine; D013601:T-Lymphocytes / Q000276:immunology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D000470:Alkaloids; D015704:CD4 Antigens; D007376:Interleukin-2; D007546:Isoquinolines; D010750:Phosphoproteins; D010879:Piperazines; D047428:Protein Kinase Inhibitors; D011948:Receptors, Antigen, T-Cell; D015240:Phorbol 12,13-Dibutyrate; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000242:Cyclic AMP; D011493:Protein Kinase C; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate