Suppression of cytoskeletal rearrangement in activated human neutrophils by botulinum C2 toxin. Impact on cellular signal transduction.
Botulinum C2 toxin, a binary toxin which selectively ADP-ribosylates nonmuscle G-actin, was used to evaluate the role of cytoskeletal rearrangement in ligand-evoked signal transduction and secretory processes in human neutrophils (polymorphonuclear leukocyte). Preincubation with the combined toxin components reduced the basal F-actin content and nearly completely suppressed the actin assembly initiated by the peptide and lipid chemoattractants formyl-methionyl-leucyl-phenylalanine, platelet activating factor, and leukotriene B4. Superoxide production and elastase secretion were increased markedly under these conditions. Concomitantly, ligand-elicited phosphoinositide hydrolysis was augmented with particular increase in inositol monophosphate. This was paralleled by a severalfold amplification of diacylglycerol formation and sustained elevation of cytosolic calcium. The toxin-effected amplification of postreceptor events and secretory responses was most pronounced in response to formyl-methionyl-leucyl-phenylalanine greater than platelet activating factor greater than leukotriene B4. All metabolic and secretory effects in C2 toxin-pretreated cells were sensitive to pertussis toxin inhibition. In conjunction with the recent finding of unchanged formyl-methionyl-leucyl-phenylalanine receptor binding and dissociation dynamics under influence of C2 (Norgauer, J., Just, I., Aktories, K., and Sklar, L. A. (1989) J. Cell Biol. 109, 1133-1140), the present investigation suggests amplification of postreceptor events as a major mechanism underlying C2 toxin-related increase in polymorphonuclear leukocyte secretory responses. Cytoskeletal rearrangement, putatively linked to phosphoinositide turnover and calcium transients, thus appears to be operative in temporal and/or spatial limitation of chemoattractant-evoked cellular signal transduction.
Grimminger
F
F
Department of Internal Medicine, Justus-Liebig-University, Giessen, Federal Republic of Germany.
Sibelius
U
U
Aktories
K
K
Just
I
I
Seeger
W
W
D000199:Actins / Q000378:metabolism; D000634:Aminoquinolines; D001905:Botulinum Toxins / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D003599:Cytoskeleton / Q000187:drug effects*; D004075:Diglycerides / Q000096:biosynthesis; D005456:Fluorescent Dyes; D006801:Humans; D007295:Inositol Phosphates / Q000096:biosynthesis; D007975:Leukotriene B4 / Q000378:metabolism; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009504:Neutrophils / Q000187:drug effects* / Q000378:metabolism; D010716:Phosphatidylinositols / Q000378:metabolism; D010972:Platelet Activating Factor / Q000494:pharmacology; D011108:Polymers; D015398:Signal Transduction; D013481:Superoxides / Q000378:metabolism
D000199:Actins; D000634:Aminoquinolines; D004075:Diglycerides; D005456:Fluorescent Dyes; D007295:Inositol Phosphates; D010716:Phosphatidylinositols; D010972:Platelet Activating Factor; D011108:Polymers; D013481:Superoxides; D007975:Leukotriene B4; D009240:N-Formylmethionine Leucyl-Phenylalanine; D001905:Botulinum Toxins; C035739:Quin2; D002118:Calcium