title: ADP-ribosylation of the GTP-binding protein Rho by Clostridium limosum exoenzyme affects basal, but not N-formyl-peptide-stimulated, actin polymerization in human myeloid leukaemic (HL60) cells.
abstract: Treatment of human myeloid leukaemic (HL60) cells with Clostridium limosum exoenzyme, which inactivates the small GTP-binding protein Rho by ADP-ribosylation, decreased the basal F-actin content. Inhibition of F-actin occurred after long-term treatment (24 h) of intact HL60 cells or after introduction of the toxin by electropermeabilization in a toxin-concentration-dependent manner. Concomitantly with the decrease in the basal F-actin content, the GTP-binding protein Rho was ADP-ribosylated in intact cells. However, Clostridium limosum toxin had no inhibitory effect on N-formyl-peptide-induced actin polymerization. Moreover, the relative N-formyl-peptide-stimulated polymerization was substantially enhanced in cells treated with Clostridium limosum transferase. In contrast with Clostridium limosum exoenzyme, component C21 of the Clostridium botulinum C2 toxin, which ADP-ribosylates G-actin, depolymerized basal F-actin and inhibited N-formyl-peptide-induced actin polymerization in electropermeabilized HL60 cells. These findings indicate that Rho proteins are involved in the basal, but not the ligand-evoked, actin polymerization in HL60 cells.
authors.affiliation: Institut für Pharmakologie und Toxikologie, Universität des Saarlandes, Homburg-Saar, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Koch
authors.forename: J
authors.initials: J
authors.lastname: Norgauer
authors.forename: K
authors.initials: K
authors.lastname: Aktories
mesh_terms: D036002:ADP Ribose Transferases / Q000378:metabolism*; D000199:Actins / Q000378:metabolism*; D000246:Adenosine Diphosphate Ribose / Q000378:metabolism*; D000595:Amino Acid Sequence; D001704:Biopolymers; D001905:Botulinum Toxins; D003013:Clostridium / Q000201:enzymology*; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006801:Humans; D007951:Leukemia, Myeloid; D008969:Molecular Sequence Data; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D020741:rho GTP-Binding Proteins
chemical_list: D000199:Actins; D001704:Biopolymers; D000246:Adenosine Diphosphate Ribose; D009240:N-Formylmethionine Leucyl-Phenylalanine; D036002:ADP Ribose Transferases; C063007:exoenzyme C3, Clostridium botulinum; D001905:Botulinum Toxins; D019204:GTP-Binding Proteins; D020741:rho GTP-Binding Proteins