title: Asbestos-induced apoptosis is protein kinase C delta-dependent.
abstract: Alveolar epithelial and mesothelial cells undergo apoptosis in response to asbestos, a phenomenon that may be important in injury and/or initiation of compensatory proliferation. Here, we report a functional role of protein kinase (PKC)delta in apoptosis by crocidolite asbestos. We first show that asbestos increases the kinase activity of PKC delta in alveolar type II epithelial cells (C10 line) and causes its translocation to mitochondria, events associated with caspase-9 cleavage and apoptosis as detected by the Apostain technique. Pretreatment of C10 cells with rottlerin (Rot), a PKC delta-selective inhibitor, before addition of asbestos prevented cleavage of caspase-9 and blocked the appearance of apoptotic cells. Asbestos-induced apoptosis also was inhibited in cells stably expressing a dominant-negative kinase-deficient mutant of PKC delta (dnPKC delta), but not dnPKC alpha. Activities of PKC alpha and PKC zeta increased after exposure to asbestos, but neither isoform migrated to mitochondria. A general inhibitor of PKCs, bisindolylmaleimide I, had no effect on asbestos-induced apoptosis. Hydrogen peroxide (H2O2) induced activation of PKCs delta, alpha, zeta, and theta, translocation of PKC delta to mitochondria, and caspase-9 cleavage. However, H2O2-induced apoptosis was not inhibited by cell lines stably expressing either dnPKC delta or dnPKC alpha, suggesting that activation of PKC delta has a distinct role in the development of asbestos-induced apoptosis.
authors.affiliation: Department of Pathology, University of Vermont College of Medicine, 89 Beaumont Avenue, Burlington, VT 05405, USA.
authors.forename: Arti
authors.initials: A
authors.lastname: Shukla
authors.forename: Maria
authors.initials: M
authors.lastname: Stern
authors.forename: Karen M
authors.initials: KM
authors.lastname: Lounsbury
authors.forename: Trisha
authors.initials: T
authors.lastname: Flanders
authors.forename: Brooke T
authors.initials: BT
authors.lastname: Mossman
mesh_terms: D000818:Animals; D017209:Apoptosis; D001194:Asbestos; D015153:Blotting, Western; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism; D002455:Cell Division; D002460:Cell Line; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005799:Genes, Dominant; D006657:Histones / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism / Q000494:pharmacology; D051379:Mice; D018613:Microscopy, Confocal; D008954:Models, Biological; D009154:Mutation; D010641:Phenotype; D010766:Phosphorylation; D020033:Protein Isoforms; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology*; D051571:Protein Kinase C-alpha; D051745:Protein Kinase C-delta; D021381:Protein Transport; D013347:Subcellular Fractions / Q000378:metabolism; D000099221:Protein Kinase C zeta
chemical_list: D001194:Asbestos; D053453:Caspase 9; D020169:Caspases; D004791:Enzyme Inhibitors; D006657:Histones; D006861:Hydrogen Peroxide; D020033:Protein Isoforms; D011493:Protein Kinase C; D051571:Protein Kinase C-alpha; D051745:Protein Kinase C-delta; D000099221:Protein Kinase C zeta; C497259:Prkcd protein, mouse; C496630:Prkca protein, mouse; C506434:Casp9 protein, mouse