Mechanisms of Siglec-F-induced eosinophil apoptosis: a role for caspases but not for SHP-1, Src kinases, NADPH oxidase or reactive oxygen

PLoS One. 2013 Jun 28;8(6):e68143. doi: 10.1371/journal.pone.0068143. Print 2013.

Abstract

Background: Siglec-F and Siglec-8 are functional paralog proapoptotic cell surface receptors expressed on mouse and human eosinophils, respectively. Whereas Siglec-8 mediated death involves caspases and/or reactive oxygen species (ROS) generation and mitochondrial injury, very little is known about Siglec-F-mediated signaling and apoptosis. Therefore the objective of the current experiments was to better define apoptosis pathways mediated by Siglec-F and Siglec-8. Given that Siglec-F-induced apoptosis is much less robust than Siglec-8-induced apoptosis, we hypothesized that mechanisms involved in cell death via these receptors would differ.

Methods: Consequences of engagement of Siglec-F on mouse eosinophils were studied by measuring ROS production, and by performing apoptosis assays using eosinophils from normal, hypereosinophilic, NADPH oxidase-deficient, src homology domain-containing protein tyrosine phosphatase (SHP)-1-deficient, and Lyn kinase-deficient mice. Inhibitors of caspase and Src family kinase activity were also used.

Results: Engagement of Siglec-F induced mouse eosinophil apoptosis that was modest in magnitude and dependent on caspase activity. There was no detectable ROS generation, or any role for ROS, NADPH oxidase, SHP-1, or Src family kinases in this apoptotic process.

Conclusions: These data suggest that Siglec-F-mediated apoptosis is different in both magnitude and mechanisms when compared to published data on Siglec-8-mediated human eosinophil apoptosis. One likely implication of this work is that models targeting Siglec-F in vivo in mice may not provide identical mechanistic predictions for consequences of Siglec-8 targeting in vivo in humans.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigens, Differentiation, Myelomonocytic / metabolism*
  • Apoptosis / physiology*
  • Caspases / metabolism*
  • Eosinophils / metabolism*
  • Eosinophils / physiology*
  • Lectins / metabolism
  • Mice
  • Mice, Inbred C57BL
  • NADPH Oxidases / metabolism
  • Protein Tyrosine Phosphatase, Non-Receptor Type 6 / metabolism
  • Reactive Oxygen Species / metabolism
  • src-Family Kinases / metabolism

Substances

  • Antigens, Differentiation, Myelomonocytic
  • Lectins
  • Reactive Oxygen Species
  • Siglecf protein, mouse
  • NADPH Oxidases
  • lyn protein-tyrosine kinase
  • src-Family Kinases
  • Protein Tyrosine Phosphatase, Non-Receptor Type 6
  • Ptpn6 protein, mouse
  • Caspases