Effect of the ostreolysin A/pleurotolysin B pore-forming complex on neuroblastoma cell morphology and intracellular Ca²⁺ activity.

Abstract

Ostreolysin A (OlyA) and pleurotolysin B (PlyB), isolated from edible oyster mushrooms, form a cytolytic complex (OlyA/PlyB) in membrane cells that causes respiratory arrest. This study evaluated the mechanisms underlying cytotoxic OlyA/PlyB activity in neuroblastoma NG108-15 cells. Confocal microscopy with morphometric analysis revealed that OlyA/PlyB increased the 3-dimensional projected area of differentiated cells. Iso-osmotic replacement of NaCl by sucrose or Na-isethionate prevented the cellular swelling. This suggests that formation of cellular edema requires the presence of Na(+) and/or Cl(-) in the extracellular space and may be related to an influx of Na(+) and/or a shift in Cl(-), which induce a marked influx of water that is ultimately responsible for cellular swelling. In addition, extracellular Ca(2+) moderately contributed to the swelling because benzamil (10 µM), a 3Na(+)/Ca(2+) exchange (NCX) inhibitor, and Ca(2+)-free medium partially prevented this response. Fluorometric measurements revealed that OlyA/PlyB, at approximately 15-fold higher concentrations, increased the intracellular Ca(2+) activity [Ca(2+)]i. This increase was dependent on the presence of Na(+) and Ca(2+) in the external medium and was sensitive to benzamil. It is thus likely that a switch in the NCX mode, associated with the de novo formation of non-selective ion pores by OlyA/PlyB in cellular plasma membranes, plays an important role in this effect. Overall, OlyA/PlyB affects neuroblastoma cell morphology and Ca(2+) homeostasis to influence the toxin-induced respiratory arrest.

• Authors: Milka Vrecl, Monika Babnik, Uroš Diacci, Evelyne Benoit, Robert Frangež
• Journal: Toxicological sciences : an official journal of the Society of Toxicology (Toxicol Sci) Vol. 144 Issue 2 Pg. 276-83 (Apr 2015) ISSN: 1096-0929 [Electronic] United States
• PMID: 25556216 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © The Author 2015. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved. For Permissions, please e-mail: [email protected].

Chemical References

• Fungal Proteins
• Hemolysin Proteins
• ostreolysin
• pleurotolysin B, oyster mushroom
• Calcium

Topics

• Animals
• Calcium (metabolism)
• Cell Line, Tumor
• Fungal Proteins (pharmacology)
• Hemolysin Proteins (pharmacology)
• Mice
• Neuroblastoma (metabolism, pathology)
• Rats