title: Rottlerin inhibits P2X(7) receptor-stimulated phospholipase D activity in chronic lymphocytic leukaemia B-lymphocytes.
abstract: Phospholipase D (PLD) is a ubiquitous enzyme that can be activated by extracellular adenosine 5'-triphosphate (ATP) or phorbol 12-myristate 13-acetate (PMA) in B-lymphocytes from subjects with chronic lymphocytic leukaemia (CLL). In this study, ATP- but not PMA-induced PLD stimulation in CLL B-lymphocytes was abolished in the presence of an anti-P2X(7) receptor monoclonal antibody, as well as in B-lymphocytes from CLL subjects homozygous for the Glu(496) to Ala loss-of-function P2X(7) polymorphism. Rottlerin, an inhibitor of novel protein kinase C (PKC) isoforms, but not GF 109203X, an inhibitor of conventional PKC isoforms, impaired the ATP-stimulated PLD activity in CLL B-lymphocytes. In contrast, both inhibitors impaired PLD activity stimulated by PMA, a known mediator of PKC activation. The inhibition of P2X(7)-stimulated PLD activity by rottlerin was attributed to a target downstream of P2X(7) activation, as the ATP-mediated (86)Rb(+) efflux from CLL B-lymphocytes was not altered in the presence of rottlerin. Our results indicate a possible role for novel PKC isoforms in the regulation of P2X(7)-mediated PLD activity.
authors.affiliation: Department of Medicine, University of Sydney at Nepean Hospital, Penrith, New South Wales, Australia.
authors.forename: Anne N
authors.initials: AN
authors.lastname: Shemon
authors.forename: Ronald
authors.initials: R
authors.lastname: Sluyter
authors.forename: James S
authors.initials: JS
authors.lastname: Wiley
mesh_terms: D000098:Acetophenones / Q000494:pharmacology*; D000255:Adenosine Triphosphate / Q000494:pharmacology; D001402:B-Lymphocytes / Q000187:drug effects / Q000201:enzymology; D001578:Benzopyrans / Q000494:pharmacology*; D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D015971:Gene Expression Regulation, Enzymologic; D015973:Gene Expression Regulation, Leukemic; D006801:Humans; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000201:enzymology*; D010739:Phospholipase D / Q000378:metabolism*; D011110:Polymorphism, Genetic; D020033:Protein Isoforms / Q000037:antagonists & inhibitors; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D018048:Receptors, Purinergic P2 / Q000378:metabolism*; D058486:Receptors, Purinergic P2X7; D012413:Rubidium / Q000378:metabolism
chemical_list: D000098:Acetophenones; D001578:Benzopyrans; C546468:P2RX7 protein, human; D020033:Protein Isoforms; D018048:Receptors, Purinergic P2; D058486:Receptors, Purinergic P2X7; D000255:Adenosine Triphosphate; C085746:rottlerin; D011493:Protein Kinase C; D010739:Phospholipase D; D012413:Rubidium