en
Scientific article
English

Aerolysin induces G-protein activation and Ca2+ release from intracellular stores in human granulocytes

Published inThe Journal of biological chemistry, vol. 273, no. 29, p. 18122-18129
Publication date1998
Abstract

Aerolysin is a pore-forming toxin that plays a key role in the pathogenesis of Aeromonas hydrophila infections. In this study, we have analyzed the effect of aerolysin on human granulocytes (HL-60 cells). Proaerolysin could bind to these cells, was processed into active aerolysin, and led to membrane depolarization, indicating that granulocytes are potential targets for this toxin. Fura-2 measurements were used to analyze the effect of aerolysin on cytosolic [Ca2+] homeostasis. As expected for a pore-forming toxin, aerolysin addition led to Ca2+ influx across the plasma membrane. In addition, the toxin triggered Ca2+ release from agonist and thapsigargin-sensitive intracellular Ca2+ stores. This Ca2+ release was independent of the aerolysin-induced Ca2+ influx and occurred in two kinetically distinct phases: an initial rapid and transient phase and a second, more sustained, phase. The first, but not the second phase was sensitive to pertussis toxin. Activation of pertussis toxin-sensitive G-proteins appeared to be a consequence of pore formation, rather than receptor activation through aerolysin-binding, as it: (i) was not observed with a binding competent, insertion-incompetent aerolysin mutant, (ii) had a marked lag time, and (iii) was also observed in response to other bacterial pore-forming toxins (staphylococcal alpha-toxin, streptolysin O) which are thought to bind to different receptors. G-protein activation through pore-forming toxins stimulated cellular functions, as evidenced by pertussis toxin-sensitive chemotaxis. Our results demonstrate that granulocytes are potential target cells for aerolysin and that in these cells, Ca2+ signaling in response to a pore-forming toxin involves G-protein-dependent cell activation and Ca2+ release from intracellular stores.

Keywords
  • Bacterial Proteins
  • Bacterial Toxins/metabolism/ pharmacology
  • Calcium/ metabolism
  • Cell Membrane Permeability/drug effects
  • Chemotaxis, Leukocyte/drug effects
  • Digitonin/pharmacology
  • GTP-Binding Proteins/ metabolism
  • Granulocytes/drug effects/ metabolism
  • HL-60 Cells
  • Hemolysin Proteins/metabolism/ pharmacology
  • Humans
  • Ion Channels/ metabolism
  • Kinetics
  • Membrane Potentials
  • N-Formylmethionine Leucyl-Phenylalanine/pharmacology
  • Pertussis Toxin
  • Pore Forming Cytotoxic Proteins
  • Potassium/metabolism
  • Streptolysins/metabolism
  • Virulence Factors, Bordetella/pharmacology
Affiliation Not a UNIGE publication
Citation (ISO format)
KRAUSE, Karl-Heinz et al. Aerolysin induces G-protein activation and Ca2+ release from intracellular stores in human granulocytes. In: The Journal of biological chemistry, 1998, vol. 273, n° 29, p. 18122–18129. doi: 10.1074/jbc.273.29.18122
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Identifiers
ISSN of the journal0021-9258
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